ORCID Profile
0000-0003-4999-4416
Current Organisations
University of Adelaide
,
University of South Australia
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Publisher: Wiley
Date: 28-09-2015
DOI: 10.1111/EJSS.12294
Publisher: Informa UK Limited
Date: 03-2003
Abstract: The most common source of elevated As concentrations in the Australian environment are attributable to anthropogenic activities. Mining activities have contributed to the contamination of soil and water primarily in Western Australia and Victoria. However, other anthropogenic activities such as agriculture, forestry and industry have also contaminated soil and water at a localized scale. Currently there are over 1000 As contaminated sites previously used as cattle dips for eradicating cattle ticks. Although As contamination of the environment may be severe enough to limit plant growth there appears to be few other reports identifying the impacts of the contaminants on other organisms, such as fish, mammals and humans. In Australia the impacts of metal/metalloid contamination of the environment are often unnoticed or ignored. However, the impacts of elements such as As may pass unnoticed by the public or regulators due to the perception of the minimal impact a contaminant has on the environment. This paper presents an overview of As in the Australian environment including the sources of As contamination, soil, water and plant As content, and the pathways of exposure.
Publisher: Elsevier BV
Date: 12-2011
DOI: 10.1016/J.JHAZMAT.2011.09.068
Abstract: In this study, As-contaminated soils (n=12) were assessed for As bioaccessibility using the Unified Bioaccessibility Research Group of Europe in vitro method (UBM) incorporating gastric, saliva-gastric or saliva-gastric-intestinal phases. Arsenic bioaccessibility was compared to previous published As relative bioavailability data for these soils to determine the correlation between in vitro and in vivo data. Comparison of in vitro and in vivo data indicated that the correlation between As bioaccessibility (UBM) and As relative bioavailability (swine assay) was similar irrespective of the in vitro phase used for its determination. The UBM incorporating all phases (saliva-gastric-intestinal) provided the best in vivo-in vitro correlation (slope=1.08 R(2)=0.59), however there was no significant difference in the goodness of fit (R(2) ranged from 0.48 to 0.59) or the slope of the lines (0.93-1.08) for either variation of the UBM (P=0.9946). This indicates that there was no improvement in the As relative bioavailability predictive capabilities when the UBM was extended from a single gastric phase to saliva-gastric or saliva-gastric-intestinal phases.
Publisher: Springer Science and Business Media LLC
Date: 23-12-2008
DOI: 10.1007/S10653-008-9237-Y
Abstract: The assessment of arsenic (As) bioavailability from contaminated matrices is a crucial parameter for reducing the uncertainty when estimating exposure for human health risk assessment. In vivo assessment of As utilising swine is considered an appropriate model for human health risk assessment applications as swine are remarkably similar to humans in terms of physiology and As metabolism. While limited in vivo As bioavailability data is available in the literature, few details have been provided regarding technical considerations for performing in vivo assays. This paper describes, with ex les, surgical, experimental design and analytical issues associated with performing chronic and acute in vivo swine assays to determine As bioavailability in contaminated soil and food.
Publisher: Springer Science and Business Media LLC
Date: 23-12-2008
DOI: 10.1007/S10653-008-9242-1
Abstract: The accumulation of arsenic (As) by vegetables is a potential human exposure pathway. The speciation of As in vegetables is an important consideration due to the varying toxicity of different As species. In this study, common Australian garden vegetables were hydroponically grown with As-contaminated irrigation water to determine the uptake and species of As present in vegetable tissue. The highest concentrations of total As were observed in the roots of all vegetables and declined in the aerial portions of the plants. Total As accumulation in the edible portions of the vegetables decreased in the order radish >> mung bean > lettuce = chard. Arsenic was present in the roots of radish, chard, and lettuce as arsenate (As(V)) and comprised between 77 and 92% of the total As present, whereas in mung beans, arsenite (As(III)) comprised 90% of the total As present. In aerial portions of the vegetables, As was distributed equally between both As(V) and As(III) in radish and chard but was present mainly as As(V) in lettuce. The presence of elevated As in vegetable roots suggests that As species may be complexed by phytochelatins, which limits As translocation to aerial portions of the plant.
Publisher: American Chemical Society (ACS)
Date: 15-09-2014
DOI: 10.1021/ES502751Z
Abstract: To evaluate the capabilities of in vitro assays to predict arsenic (As) relative bioavailability (RBA), we examined the relationship between As bioaccessibility, determined using a number of in vitro bioaccessibility (IVBA) methodologies (SBRC, IVG, PBET, DIN and UBM) and As RBA determined in a mouse assay for nine As-contaminated soils and 1 NIST reference material (2710a). Significant differences (P < 0.05) in As IVBA were observed within and between assays indicating that different IVBA methodologies may not produce congruent data, as a result of variability in the extracting medium constituents and/or differences in the pH of gastric and intestinal phases. When results of in vivo determinations of As RBA were compared with As IVBA results, there was no significant difference in slopes of the relationships (P = 0.49-0.88) when SBRC, IVG, PBET, DIN, and UBM gastric and intestinal phase data were used. A significantly (P < 0.05) smaller y-intercept was, however, determined for the in vivo-SBRC gastric phase correlation compared to SBRC, IVG, PBET, and DIN intestinal phase, a factor that may influence prediction of As RBA, especially for soils with low As RBA. When in vivo-in vitro relationships were compared to previously derived correlations from the literature, some differences were observed. These differences may be attributed to factors affecting both in vivo and in vitro data including physiological differences in animal models (e.g., mouse versus swine), which may influence As absorption, differences in the approach used to estimate As RBA, and variability arising from subtle interoperator differences in performance of in vitro assays.
Publisher: Elsevier BV
Date: 02-2017
DOI: 10.1016/J.CHEMOSPHERE.2016.11.010
Abstract: Incidental ingestion of contaminated soil and dust is a major pathway for human exposure to many inorganic contaminants. To date, exposure research has focused on arsenic (As), cadmium (Cd) and lead (Pb), however, these studies have typically assessed metal(loid) bioavailability in idually, even when multiple elements are present in the same matrix. As a consequence, it is unclear whether interactions between these elements occur within the gastro-intestinal tract, which may impact absorption and accumulation. In this study, the influence of contaminant co-exposure was assessed using a mouse bioassay and soluble forms of As, Cd and Pb supplied in mouse chow as in idual, binary and tertiary elemental combinations. Arsenic urinary excretion and Pb-liver accumulation were unaffected by As-Pb co-exposure (1-10 mg As kg
Publisher: American Chemical Society (ACS)
Date: 11-05-2009
DOI: 10.1021/ES803238U
Abstract: In this study, lead (Pb) bioaccessibility in contaminated soils was assessed using an in vitro method (SBRC) encompassing gastric (SBRC-G) and intestinal (SBRC-I) phases. Initially, bioaccessibility studies were performed with a Pb reference material (Pb acetate, 1-10 mg L(-1)) in order to determine the influence of pH on Pb solubility. In the gastric phase (pH 1.5), Pb solubility was 100% (100 +/- 2.9%, n = 16) irrespective of the Pb concentration added, however, when the pH of the intestinal phase was increased to near neutral, Pb solubility decreased to 14.3 +/- 7.2%. In contaminated soils, Pb bioaccessibility varied from 35.7 to 64.1% and 1.2 to 2.7% for SBRC-G and SBRC-I phases, respectively. When relative bioaccessibility (Rel-SBRC-I) was calculated by adjusting the dissolution of Pb from contaminated soils by the solubility of Pb acetate at pH 6.5 (intestinal phase pH) Rel-SBRC-I values ranged from 11.7-26.1%. A stepwise regression model based on Pearson correlation factors was used to determine the suitability of in vitro assays for predicting in vivo (swine assay) relative Pb bioavailability. Rel-SBRC-I provided the best estimate of in vivo relative Pb bioavailability for soils used in this study (in vive relative Pb bioavailability [%] = Rel-SBRC-I [pH 6.5%] x 0.58 + 1.98, P = 0.53). The versatility of Rel-SBRC-I was demonstrated by accurately predicting relative Pb bioavailability from other reported in vivo studies.
Publisher: American Chemical Society (ACS)
Date: 23-10-2014
DOI: 10.1021/ES503695G
Abstract: A number of bioaccessibility methodologies have the potential to act as surrogate measures of arsenic (As) relative bioavailability (RBA), however, validation of the in vivo-in vitro relationship is yet to be established. Validation is important for human health risk assessment in order to ensure robust models for predicting As RBA for refining exposure via incidental soil ingestion. In this study, 13 As-contaminated soils were assessed for As RBA (in vivo swine model) and As bioaccessibility (Solubility Bioaccessibility Research Consortium gastric phase extraction SBRC-G). In vivo and in vitro data were used to assess the validity of the As RBA-bioaccessibility correlation previously described by Juhasz et al. (2009). Arsenic RBA and bioaccessibility in the 13 soils ranged from 6.8±2.4% to 70.5±6.8% and 5.7±0.3% to 78.4±0.8% respectively with a strong linear relationship (R2=0.75) between in vivo and in vitro assays. When the As in vivo-in vitro correlation was compared that of Juhasz et al. (2009), there was no significant difference (P>0.05) indicating that the relationship between As RBA and As bioaccessibility was consistent thereby demonstrating its validation. For these data, a grouped linear regression model was developed (R2=0.82) with a slope and y-intercept of 0.84 and 3.56 respectively. A number of cross validation methodologies (2-fold, repeat random subs ling, leave one out) were utilized to determine the performance of the linear regression model. Residuals and prediction errors ranged from 5.4 to 9.4 and 6.9-12.2 respectively illustrating the capacity of the SBRC-G to accurately predict As RBA in contaminated soil.
Publisher: Wiley
Date: 03-2002
DOI: 10.2134/JEQ2002.5570
Publisher: Wiley
Date: 11-1999
Publisher: American Chemical Society (ACS)
Date: 29-07-2019
Publisher: American Chemical Society (ACS)
Date: 28-10-2015
Abstract: This study aimed to assess and compare the in vitro and in vivo bioaccessibility/bioavailability of As and Pb in a mining contaminated soil (As, 2267 mg kg(-1) Pb, 1126 mg kg(-1)), after the addition of conventional (phosphoric acid), opportunistic [water treatment residues (WTRs)], and engineered [nano- and microscale zero valent iron (ZVI)] amendments. Phosphoric acid was the only amendment that could significantly decrease Pb bioaccessibility with respect to untreated soil (41 and 47% in the gastric phase and 2.1 and 8.1% in the intestinal phases, respectively), giving treatment effect ratios (TERs, the bioaccessibility in the amended soil ided by the bioaccessibility in the untreated soil) of 0.25 and 0.87 in the gastric and intestinal phase, respectively. The in vivo bioavailability of Pb decreased in the phosphate treatment relative to the untreated soil (6 and 24%, respectively), and also in the Fe WTR 2% (12%) and nZVI-2 (13%) treatments. The ZVI amendments caused a decrease in As bioaccessibility, with the greatest decrease in the nZVI2-treated soil (TERs of 0.59 and 0.64 in the gastric and intestinal phases, respectively). Arsenic X-ray absorption near-edge spectroscopy analysis indicated that most of the As in the untreated soil was present as As(V) associated with Fe mineral phases, whereas in the treated soil, the proportion of arsenosiderite increased. Arsenite was present only as a minor species (3-5%) in the treated soils, with the exception of an nZVI treatment [∼14% of As(III)], suggesting a partial reduction of As(V) to As(III) caused by nZVI oxidation.
Publisher: Oxford University Press (OUP)
Date: 05-09-2010
DOI: 10.1093/JXB/ERQ270
Publisher: CSIRO Publishing
Date: 2011
DOI: 10.1071/SR11192
Abstract: In Australia, application of winery wastewater to land is increasingly being viewed as the most environmentally sound and cost-effective means of disposal. This wastewater contains high concentrations of both sodium (Na+) and potassium (K+), which have the potential to accumulate in the profile of irrigated soils and adversely alter physical properties such as aggregate stability and hydraulic conductivity. Cation exchange equilibria in soil of mixed illite and kaolinite mineralogy have been investigated in binary Ca–Na and Ca–K systems and in a ternary Ca–Na–K system. In the respective binary systems, resulting exchangeable potassium percentage was nearly twice the corresponding exchangeable sodium percentage (ESP), indicating a high binding affinity of K+ in this soil. In a ternary system, soils were equilibrated with solutions of differing sodium adsorption ratio (SAR) and potassium adsorption ratio (PAR) within ranges typical of winery wastewater. The presence of K+ had a significant effect on the relationship between SAR and ESP, whereby ESP decreased with increasing PAR. Resulting ESP in the ternary system was consistently lower than in the binary system. Cation selectivity between solid and solution phases in the ternary system was calculated from the Vanselow and K-selectivity coefficients and showed a decreasing selectivity for Na+ with increasing K+ in solution. It is expected that, due to the high K+ content of winery wastewater (i.e. mg/L), adsorption of Na+, and subsequent ESP, will be less than in wastewaters of comparable Na+ concentration yet absent K+.
Publisher: Elsevier BV
Date: 12-2007
Publisher: Springer Science and Business Media LLC
Date: 14-06-2015
DOI: 10.1007/S11356-013-1820-9
Abstract: Bioavailability (BA) determines the potential harm of a contaminant that exerts on the receptor. However, environmental guidelines for site contamination assessment are often set assuming the contaminant is 100 % bioavailable. This conservative approach to assessing site risk may result in the unnecessary and expensive remediation of a contaminated site. The National Environmental Protection Measures in Australia has undergone a statutory 5-year review that recommended that contaminant bioavailability and bioaccessibility (BAC) measures be adopted as part of the contaminated site risk assessment process by the National Environment Protection Council. We undertook a critical review of the current bioavailability and bioaccessibility approaches, methods and their respective limitations. The 'gold' standard to estimate the portion of a contaminant that reaches the system circulatory system (BA) of its receptor is to determine BA in an in vivo system. Various animal models have been utilised for this purpose. Because of animal ethics issues, and the expenses associated with performing in vivo studies, several in vitro methods have been developed to determine BAC as a surrogate model for the estimation of BA. However, few in vitro BAC studies have been calibrated against a reliable animal model, such as immature swine. In this review, we have identified suitable methods for assessing arsenic and lead BAC and proposed a decision tree for the determination of contaminant bioavailability and bioaccessibility for health risk assessment.
Publisher: Hindawi Limited
Date: 12-12-2012
Publisher: Elsevier BV
Date: 2017
DOI: 10.1016/J.SCITOTENV.2016.09.056
Abstract: Inhalation of metal(loid)s in ambient particulate matter (APM) represents a significant exposure pathway to humans. Although exposure assessment associated with this pathway is currently based on total metal(loid) content, a bioavailability (i.e. absorption in the systemic circulation) and/or bioaccessibility (i.e. solubility in simulated lung fluid) based approach may more accurately quantify exposure. Metal(loid) bioavailability-bioaccessibility assessment from APM is inherently complex and lacks consensus. This paper reviews the discrepancies that impede the adoption of a universal protocol for the assessment of inhalation bioaccessibility. Exposure assessment approaches for in-vivo bioavailability, in-vitro cell culture and in-vitro bioaccessibility (composition of simulated lungs fluid, physico-chemical and methodological considerations) are critiqued in the context of inhalation exposure refinement. An important limitation of bioavailability and bioaccessibility studies is the use of considerably higher than environmental metal(loid) concentration, which diminishing their relevance to human exposure scenarios. Similarly, in idual metal(loid) studies have been criticised due to complexities of APM metal(loid) mixtures which may impart synergistic or antagonistic effects compared to single metal(loid) exposure. Although a number of different simulated lung fluid (SLF) compositions have been used in metal(loid) bioaccessibility studies, information regarding the comparative leaching efficiency among these different SLF and comparisons to in-vivo bioavailability data is lacking. In addition, the particle size utilised is often not representative of what is deposited in the lungs while assay parameters (extraction time, solid to liquid ratio, temperature and agitation) are often not biologically relevant. Research needs are identified in order to develop robust in-vitro bioaccessibility protocols for the assessment or prediction of metal(loid) bioavailability in APM for the refinement of inhalation exposure.
Publisher: American Chemical Society (ACS)
Date: 15-11-2011
DOI: 10.1021/ES2018384
Abstract: A number of in vitro assays are available for the determination of arsenic (As) bioaccessibility and prediction of As relative bioavailability (RBA) to quantify exposure for site-specific risk assessment. These data are usually considered in isolation however, meta analysis may provide predictive capabilities for source-specific As bioaccessibility and RBA. The objectives of this study were to predict As RBA using previously published in vivo/in vitro correlations and to assess the influence of As sources on As RBA independent of geographical location. Data representing 351 soils (classified based on As source) and 514 independent bioaccessibility values were retrieved from the literature for comparison. Arsenic RBA was predicted using published in vivo/in vitro regression models, and 90th and 95th percentiles were determined for each As source classification and in vitro methodology. Differences in predicted mean As RBA were observed among soils contaminated from different As sources and within source materials when various in vitro methodologies were utilized. However, when in vitro data were standardized by transforming SBRC intestinal, IVG, and PBET data to SBRC gastric phase values (through linear regression models), predicted As RBA values for As sources followed the order CCA posts ≥ herbicide esticide > mining/smelting > gossan soils with 95th percentiles for predicted As RBA of 78.0, 78.4, 67.0, and 23.7%, respectively.
Publisher: Elsevier BV
Date: 10-2017
DOI: 10.1016/J.SCITOTENV.2017.04.036
Abstract: In this study, the influence of s le matrix on the relative bioavailability of arsenic (As), cadmium (Cd) and lead (Pb) was assessed following exposure of C57BL/6 mice to spiked aged (12years) soils. AIN93G mouse chow was amended with in idual and tertiary As, Cd and Pb soil combinations which were administered to mice over a 9day exposure period. Contaminant relative bioavailability was calculated by comparing As urinary excretion and Cd-kidney/Pb-liver accumulation to corresponding values for compounds used to derive the respective toxicity reference value. Strong linear dose-responses were observed for mice exposed to AIN93G mouse chow augmented with in idually spiked soil with As, Cd and Pb. When mice were exposed to co-contaminants, As relative bioavailability (RBA) decreased similar to results from previous co-contaminant salt experiments presumably due to the influence of Cd on phosphate transport proteins, which are utilized for As absorption. However, a decrease in Cd-kidney and Pb-liver accumulation was also observed following co-co-exposure. It was postulated that this resulted from interactions with other (essential) metals (e.g. iron, aluminium, manganese, magnesium) within the soil matrix and their influence on absorption via alent metal transporters.
Publisher: American Chemical Society (ACS)
Date: 07-11-2008
DOI: 10.1021/ES801767B
Abstract: Despite the existence of many single ion sorption studies on iron and aluminum oxides, fewer studies have been reported that describe cosorption reactions. In this work, we present an in situ ATR FTIR study of synergistic adsorption of sulfate (SO4) and copper (Cu) on goethite, which is representative of the minerals and ions present in mine wastes, acid sulfate soils, and other industrial and agricultural settings. Sulfate adsorption was studied as a function of varying pH, and as a function of increasing concentration in the absence and presence of Cu. The presence of Cu ions in solution had a complex effect on the ability of SO4 ions to be retained on the goethite surface with increasing pH, with complete desorption occurring near pH 7 and 9 in the absence and presence of Cu, respectively. In addition, Cu ions altered the balance of inner vs outer sphere adsorbed SO4. The solid phase partitioning of SO4 at pH 3 and pH 5 was elevated by the presence of Cu in both cases Cu increased the affinity of SO4 for the goethite surface. Complementary ex situ sorption edge studies of Cu on goethite in the absence and presence of SO4 revealed that the Cu adsorption edge shifted to lower pH (6.3 --> 5.6) in the presence of SO4, consistent with a decrease of the electrostatic repulsion between the goethite surface and adsorbing Cu. Based on the ATR FTIR and bulk sorption data we surmise that the cosorption products of SO4 and Cu at the goethite-water interface were not in the nature of ternary complexes under the conditions studied here. This information is critical for the evaluation of the onset of surface precipitates of copper-hydroxy sulfates as a function of pH and solution concentration.
Publisher: Elsevier BV
Date: 02-2011
DOI: 10.1016/J.JHAZMAT.2010.10.111
Abstract: Lead (Pb) bioaccessibility was assessed in a range of peri-urban soils (n=31) with differing sources of Pb contamination, including shooting range soils, and soils affected by incinerator, historical fill, mining/smelting, and gasworks activities. A gossan soil s le was also included. Lead bioaccessibility was determined using both gastric and intestinal phases of the SBRC in vitro assay and in vitro data was then incorporated into in vivo-in vitro regression equations to calculate Pb relative bioavailability. Lead bioaccessibility ranged from 26.8-105.2% to 5.5-102.6% for gastric and intestinal phase extractions respectively. Generally, Pb bioaccessibility was highest in the shooting range soils and lowest in the gossan soil. Predictions of relative Pb bioavailability derived from in vitro data were comparable for shooting ranges soils, but highly variable for the other soils examined. For incinerator, historical fill, gasworks and gossan soils, incorporating in vitro gastric data into the in vivo-in vitro regression equation resulting in more conservative Pb relative bioavailability values than those derived using the intestinal in vitro data.
Publisher: Elsevier BV
Date: 10-2016
DOI: 10.1016/J.ENVRES.2016.06.039
Abstract: In this study, the bioavailability of DDTr (sum of DDT, DDD and DDE isomers) in pesticide-contaminated soil was assessed using an in vivo mouse model. DDTr relative bioavailability (RBA) ranged from 18.7±0.9 (As35) to 60.8±7.8% (As36) indicating that a significant portion of soil-bound DDTr was not available for absorption following ingestion. When DDTr bioaccessibility was assessed using the organic Physiologically Based Extraction Test (org-PBET), the inclusion of a sorption sink (silicone cord) enhanced DDTr desorption by up to 20-fold (1.6-3.8% versus 18.9-56.3%) compared to DDTr partitioning into gastrointestinal fluid alone. Enhanced desorption occurred as a result of the silicone cord acting as a reservoir for solubilized DDTr to partition into, thereby creating a flux for further desorption until equilibrium was achieved. When the relationship between in vivo and in vitro data was assessed, a strong correlation was observed between the mouse bioassay and the org-PBET+silicone cord (slope=0.94, y-intercept=3.5, r(2)=0.72) suggesting that the in vitro approach may provide a robust surrogate measure for the prediction of DDTr RBA in contaminated soil.
Publisher: Elsevier BV
Date: 09-2013
DOI: 10.1016/J.ENVPOL.2013.05.008
Abstract: A number of studies have shown the potential of in vitro assays to predict contaminant in vivo relative bioavailability in order to refine human health exposure assessment. Although the term 'validated' has been used to describe the goodness of fit between in vivo and in vitro observations, its misuse has arisen from semantic considerations in addition to the lack of defined criteria for establishing performance validation. While several internal validation methods may be utilised, performance validation should preferably focus on assessing the agreement of model predictions with a set of data which are independent of those used to construct the model. In order to achieve robust validated predictive models, a number of parameters (e.g. size of data set, source of independent soils, contaminant concentration range, animal model, relative bioavailability endpoint) need to be considered in addition to defined criteria for establishing performance validation which are currently lacking.
Publisher: IOP Publishing
Date: 17-12-2014
Publisher: Environmental Health Perspectives
Date: 12-2006
DOI: 10.1289/EHP.9322
Abstract: Millions of people worldwide consume arsenic-contaminated rice however, little is known about the uptake and bioavailability of arsenic species after arsenic-contaminated rice ingestion. In this study, we assessed arsenic speciation in greenhouse-grown and supermarket-bought rice, and determined arsenic bioavailability in cooked rice using an in vivo swine model. In supermarket-bought rice, arsenic was present entirely in the inorganic form compared to greenhouse-grown rice (using irrigation water contaminated with sodium arsenate), where most (approximately 86%) arsenic was present as dimethylarsinic acid (organic arsenic). Because of the low absolute bioavailability of dimethylarsinic acid and the high proportion of dimethylarsinic acid in greenhouse-grown rice, only 33 +/- 3% (mean +/- SD) of the total rice-bound arsenic was bioavailable. Conversely, in supermarket-bought rice cooked in water contaminated with sodium arsenate, arsenic was present entirely in the inorganic form, and bioavailability was high (89 +/- 9%). These results indicate that arsenic bioavailability in rice is highly dependent on arsenic speciation, which in turn can vary depending on rice cultivar, arsenic in irrigation water, and the presence and nature of arsenic speciation in cooking water. Arsenic speciation and bioavailability are therefore critical parameters for reducing uncertainties when estimating exposure from the consumption of rice grown and cooked using arsenic-contaminated water.
Publisher: American Chemical Society (ACS)
Date: 12-05-2015
Abstract: In vitro bioaccessibility (IVBA) assays estimate arsenic (As) relative bioavailability (RBA) in contaminated soils to improve accuracy in human exposure assessments. Previous studies correlating soil As IVBA with RBA have been limited by the use of few soil types and sources of As, and the predictive value of As IVBA has not been validated using an independent set of As-contaminated soils. In this study, a robust linear model was developed to predict As RBA in mice using IVBA, and the predictive capability of the model was independently validated using a unique set of As-contaminated soils. Forty As-contaminated soils varying in soil type and contaminant source were included in this study, with 31 soils used for initial model development and nine soils used for independent model validation. The initial model reliably predicted As RBA values in the independent data set, with a mean As RBA prediction error of 5.4%. Following validation, 40 soils were used for final model development, resulting in a linear model with the equation RBA = 0.65 × IVBA + 7.8 and an R(2) of 0.81. The in vivo-in vitro correlation and independent data validation presented provide critical verification necessary for regulatory acceptance in human health risk assessment.
Publisher: Elsevier BV
Date: 02-2011
DOI: 10.1016/J.JHAZMAT.2010.12.095
Abstract: The impact of soil particle size and bioaccessibility on children and adult lead (Pb) exposure via the incidental soil ingestion pathway was assessed in 16 peri-urban contaminated soils. A comparison of Pb distribution across 4 particle size fractions (<50 μm, <100 μm, <250 μm and <2 mm) found increasing Pb concentrations associated with decreasing particle size fractions. Lead enrichment in the <50 μm particle size fraction was up to 5 times the concentration observed in the bulk soil. When gastric phase Pb bioaccessibility was determined in the <50, <100 and <250 μm particle size fractions using the SBRC assay, Pb bioaccessibility also increased with decreasing particle size fraction for 6 of the 16 soils tested. Assessment of children and adult Pb exposure indicated that particle size and bioaccessibility had a significant influence on the contribution of incidental soil ingestion to daily Pb intake values. Although the <250 μm particle size fraction is recommended for incidental soil ingestion calculations, using this fraction has the potential to underestimate Pb exposure due to the preferential adhesion of smaller particles to hands with elevated Pb concentrations.
Publisher: Elsevier BV
Date: 06-2008
DOI: 10.1016/J.JCIS.2008.02.044
Abstract: The co-sorption reaction products of arsenate (As(V)) and copper (Cu(II)) on goethite (alpha-FeOOH) and natro-jarosite (Na(3)Fe(3)(SO(4))(2)(OH)(6)) were investigated with extended X-ray absorption fine structure (EXAFS) spectroscopy to determine if Cu(II) and As(V) would form precipitates or compete with each other for surface sites. The reaction products were prepared by mixing 250 microM Cu(SO(4)) with 10, 25, or 50 microM Na(2)HAsO(4) at pH 5.65 and allowing the mixture to react in 10 m(2) L(-1) goethite or jarosite suspensions for 12 days. In addition, EXAFS data of Cu(SO(4)) and As(V) sorbed on goethite and jarosite were collected as control species. All reaction conditions were under-saturated with respect to common copper bearing minerals: tenorite (CuO), brochantite (Cu(4)(OH)(6)SO(4)), and hydrated clinoclase (Cu(3)(AsO(4))(2)2H(2)O). The extents of the As(V) and Cu(II) surface adsorption reactions showed a strong competitive effect from Cu(II) on As(V) adsorption for a nominal Cu:As mole-ratio of 25:1. With increasing nominal As(V) concentration, As(V) sorption on goethite and jarosite increased without diminishing the amount of Cu(II) sorption. In the absence of either co-sorbate, As(V) and Cu(II) formed the expected surface adsorption species, i.e., bidentate binuclear and edge-sharing surface complexes, consistent with previously published results. In each other's presence, the local bonding environments of As(V) and Cu(II) showed that the co-sorbates form a precipitate on the goethite and jarosite surface at nominal concentrations of 10:1 and 5:1. At nominal Cu:As mole-ratios of 25:1, Cu(II) did not form significantly different surface complexes on goethite or jarosite from those in the absence of As(V), however, As K-edge EXAFS results distinctly showed Cu(II) atoms in As(V)'s local bonding environment on the goethite surface. The structures of the two precipitates were different and depended on the anion-layer structure and possibly the presence of structural oxyanions in the case of jarosite. On goethite, the copper-arsenate precipitate was similar to hydrated clinoclase, while on jarosite, a euchroite-like precipitate (Cu(2)[AsO(4)](OH)3H(2)O, P 2(1)2(1)2(1)) had formed. Despite under-saturated solution conditions, the formation of these precipitates may have occurred due to a seed-formation effect from densely surface adsorbed Cu(II) and As(V) for which the "new" saturation index was significantly lower than homogeneous values would otherwise suggest. Synergistic reactions between two co-sorbates of fundamentally different surface adsorption behaviour can thus be achieved if the number of available sites for surface adsorption is limited.
Publisher: Elsevier BV
Date: 02-2016
DOI: 10.1016/J.ENVRES.2015.12.001
Abstract: PAH bioaccessibility in contaminated soil was determined using the organic physiologically based extraction test with the inclusion of a sorption sink. Silicone cord was incorporated into the assay in order to overcome the limited capacity of the in vitro medium to accommodate desorbable PAHs. Initially, silicone cord sorption efficacy was determined by assessing sorption kinetics using PAH-spiked sand (phenanthrene, pyrene and benzo[a]pyrene 10-1000mgkg(-1)). Irrespective of PAH and concentration, >95% of the initial PAH mass partitioned into the silicone cord within 12h although rates were lower at higher concentration and with increasing hydrophobicity. When PAH bioaccessibility was assessed in contaminated soil (n=18), contamination source (i.e. pyrogenic versus petrogenic) influenced PAH bioaccessibility. In idual PAH bioaccessibility ranged up to 81.7±2.7% although mean values ranged from 2.1 (acenaphthalene) to 20.8% (benzo[k]fluoranthene) with upper 95% confidence intervals of the means of 4.5 and 28.3% respectively. Although a PAH in vivo-in vitro correlation is yet to be established, bioaccessibility approaches incorporating sorption sinks represent a robust approach for estimating PAH bioavailability as the desorbable fraction may be a conservative measure of the absorbable fraction.
Publisher: Springer Science and Business Media LLC
Date: 19-11-2013
Publisher: American Chemical Society (ACS)
Date: 28-08-2019
Publisher: Springer Science and Business Media LLC
Date: 03-01-2009
DOI: 10.1007/S10653-008-9230-5
Abstract: A comparative study of arsenic enrichment in the Bengal Delta (BD) was carried out in three alluvial aquifers in south-central Bangladesh. Investigated sites included Sonargaon in Narayanganj, Chandina in Comilla and Sirajdikhan in Munshiganj districts. At all sites s les from different depths were collected, and water chemistry and redox status vs. depth trends were determined. The concentrations of DOC and HCO(3)(-) were highest at Sirajdikhan site, while at the Sonargaon and Chandina sites the concentrations were lower. On the contrary, the NH(4)(+) concentration was high at the Chandina site as compared to the other sites. There was a good match between dissolved As and Fe at the Sirajdikhan and Sonargaon sites, but not at the Chandina site. The dissolved aqueous concentration of Mn was low at the Chandina site, which suggested that the Mn(IV) redox buffering step was missing. Speciation modeling indicated a possibility of siderite precipitation at all sites, but precipitation of rhodochrosite only at the Sonargaon and Sirajdikhan sites. At the Sirajdikhan site, the log P(CO2) values were very high (-1.37), which revealed the production of CO(2) in redox processes. Principal component analysis (PCA) indicated an impact of sea water and redox status of different s les. These results suggest that the dissolved As is de-coupled from dissolved Mn because when released, As is re-adsorbed onto the Fe(III) minerals in solid phase, as well as from dissolved Fe when precipitation of Fe(II) minerals controls the aqueous concentrations of Fe. In addition, several other concurrent redox processes may exert kinetic constraints depending on refractory characteristics of Fe(III) minerals.
Publisher: Informa UK Limited
Date: 05-2013
DOI: 10.1080/10934529.2013.731354
Abstract: In this study, lead (Pb) bioaccessibility was assessed in peri-urban contaminated soils using a variety of established in vitro assays. Bioaccessibility data was then used to predict Pb relative bioavailability (RBA) using published in vivo-in vitro regression models in order to compare calculated estimates and measured values. Lead bioaccessibility varied depending on the in vitro methodology employed with the relative bioavailability leaching procedure (RBALP) and in vitro gastrointestinal (IVG) assays providing more conservative Pb bioaccessibility values compared to those determined using PBET, UBM and Rel-SBRC-I assays. When Pb RBA was calculated, predicted values using PBET-G and UBM-G data were similar to measured Pb RBA values. However, Pb RBA was over-estimated by 1.6-5.5- and 2.6-6.6-fold when data and regression models from RBALP and IVG-G assays were employed.
Publisher: American Chemical Society (ACS)
Date: 12-11-2009
DOI: 10.1021/ES902427Y
Abstract: Currently, a number of in vitro methods are in use worldwide to assess arsenic (As) bioaccessibility in soils. However, a dearth of research has been undertaken to compare the efficacy of the in vitro methods for estimating in vivo relative As bioavailability. In this study, As bioaccessibility in contaminated soils (n = 12) was assessed using four in vitro assays (SBRC, IVG, PBET, DIN). In vitro results were compared to in vivo relative As bioavailability data (swine assay) to ascertain which methodologies best correlate with in vivo data. Arsenic bioaccessibility in contaminated soils varied depending on the in vitro method employed. For the SBRC and IVG methods, As bioaccessibility generally decreased when gastric-phase values were compared to the intestinal phase. In contrast, extending the PBET and DIN assays from the gastric to the intestinal phase resulted in an increase in As bioaccessibility for some soils tested. Comparison of in vitro and in vivo results demonstrated that the in vitro assay encompassing the SBRC gastric phase provided the best prediction of in vivo relative As bioavailability (R(2) = 0.75, Pearson correlation = 0.87). However, relative As bioavailability could also be predicted using gastric or intestinal phases of IVG, PBET, and DIN assays but with varying degrees of confidence (R(2) = 0.53-0.67, Pearson correlation = 0.73-0.82).
Publisher: Springer Science and Business Media LLC
Date: 05-02-2012
DOI: 10.1007/S11356-012-0781-8
Abstract: BACKGROUND, SCOPE, AND AIMS: Antibacterial fluoroquinolones (FQs) are third-generation antibiotics that are commonly used as therapeutic treatments of respiratory and urinary tract infections. They are used far less in intensively farmed animal production systems, though their use may be permitted in the veterinary treatments of flocks or in medicated feeds. When used, only a fraction of ingested parent FQ actually reaches the in vivo target site of infection, while the remainder is excreted as the parent FQ and its metabolized products. In many species' metabolism, enrofloxacin (EF) is converted into ciprofloxacin (CF) while both FQs are classified as parent FQs in human treatments. It is therefore likely that both FQs and their metabolic products will contribute to a common pool of metabolites in biological wastes. Wastes from intensive farming practices are either directly applied to agricultural land without treatment or may be temporarily stored prior to disposal. However, human waste is treated in sewage treatment plants (STPs) where it is converted into biosolids. In the storage or treatment process of STPs, FQs and their in vivo metabolites are further converted into other environmental metabolites (FQEMs) by ex vivo physicochemical processes that act and interact to produce complex mixtures of FQEMs, some of which have antibacterial-like activities. Biosolids are then often applied to agricultural land as a fertilizer amendment where FQs and FQEMs can be further converted into additional FQEMs by soil processes. It is therefore likely that FQ-contaminated biowaste-treated soils will contain complex mixtures of FQEMs, some of which may have antibacterial-like activities that may be expressed on bacteria endemic to the receiving agricultural soil environment. Concern has arisen in the scientific and in the general community that repeated use of FQ-contaminated biowaste as fertilizer amendments of nutrient-impoverished agricultural land may create a selective environment in which FQ-resistant bacteria might grow. The likelihood of this happening will depend, to some extent, on whether bioactive FQEMs are first synthesized from the parent FQs by the action and interaction of in vivo and ex vivo processes producing bioactive FQEMs in biowastes and biosolids. The postulated creation of a selective environment will also depend, in part, on whether such bioactive FQEMs are biologically available to bacteria, which may, in turn, be influenced by soil type, amendment regime, and the persistence of the bioactive FQEMs. Additionally, soil bacteria and soil processes may be affected in different ways or extents by bioactive FQEMs that could possibly act additively or synergistically at ecological targets in these non-target bacteria. This is an important consideration, since, while parent FQs have well-defined ecological targets (DNA gyrase and topoisomerase IV) and modes of bactericidal action, the FQEMs and their possible modes of action on the many different species of soil bacteria is less well studied. It is therefore understandable that there is a lack of conclusive evidence directly attributing biosolid usage to any increase in FQ-resistant bacteria detected in biowaste-amended agricultural soil. However, a lack of evidence may simply imply that a causal relationship between biosolid usage programs and any detection of low levels of FQ-resistant bacteria in soils has yet to be established, rather than an assumption of no relationship whatsoever. Based on results presented in this paper, the precautionary principle should be applied in the usage of FQ-contaminated biosolids as fertilizer amendments of agricultural land. The aim of this research was to test whether any bioactive FQEMs of EF could be synthesized by aerobic fermentation processes using Mycobacterium gilvum (American Tissue Culture Collection) and a mixed culture of microorganisms derived from an agricultural soil. High-performance thin-layer chromatography (HPTLC) and bioautography were tested as screening techniques in the detection and analysis of bioactive FQEMs. FQEMs derived from M. gilvum and mixed (soil) culture aerobic ferments were fractionated using preparative HPTLC. A standard strain of Escherichia coli was then used as the reporter organism in a bioautography assay in the detection of bioactive-FQEMs on a mid-section of the HPTLC plate. Plate sections were reassembled, and a photograph was taken under low-intensity ultraviolet (UV) light to reveal regions that contained analytes that had UV chromophores and antibacterial-like activities. Many fractionated FQEMs displayed antibacterial-like activity while bound to silica gel HPTLC plates. These results also provide evidence that sufficient quantities of biologically active FQEMs were biologically available from a silica gel surface to prevent the adherent growth of E. coli. Six to seven FQEMs derived from EF using aerobic fermentation processes had antibacterial-like activities, while two FQEMs were also detectable using UV light. Furthermore, similar banding patterns of antibacterial-like activity were observed in both the monoculture (M. gilvum) and mixed culture bioautography assays, indicating that similar processes operated in both aerobic fermentations, either producing similar biologically active FQEMs or biologically active FQEMs that had similar physicochemical properties in both ferments. The simplest explanation for these findings is that the tested agricultural soil also contained mycobacteria that metabolized EF in a similar way to the purchased standard monoculture M. gilvum. Additionally, the marked contrast between the bioautography results and the UV results indicated that the presence of UV chromophores is not a prerequisite for the detection of antibacterial-like activity. A reliance on spectrophotometric techniques in the detection of bioactive FQEMs in the environment may underestimate component antibacterial-like activity and, possibly, total antibacterial-like activity expressed by EF and its FQEMs. The described bioautography method provides a screening technique with which antibacterial-like activities derived from EF and possibly other FQs can be detected directly on silica gel HPTLC plates. It is recommended that both bioassay and instrumental analytical techniques be used in any measurement of hazard and risk relating to antibacterial-like activities in the environment that are derived from fluoroquinolone antibiotics and their environmental metabolites.
Publisher: Elsevier BV
Date: 02-2010
DOI: 10.1016/J.ENVPOL.2009.08.018
Abstract: The impact of residual PAHs (2250 +/- 71 microg total PAHs g(-1)) following enhanced natural attenuation (ENA) of creosote-contaminated soil (7767 +/- 1286 microg total PAHs g(-1)) was assessed using a variety of ecological assays. Microtox results for aqueous soil extracts indicated that there was no significant difference in EC(50) values for uncontaminated, pre- and post-remediated soil. However, in studies conducted with Eisenia fetida, PAH bioaccumulation was reduced by up to 6.5-fold as a result of ENA. Similarly, Beta vulgaris L. biomass yields were increased 2.1-fold following ENA of creosote-contaminated soil. While earthworm and plant assays indicated that PAH bioavailability was reduced following ENA, the residual PAH fraction still exerted toxicological impacts on both receptors. Results from this study highlight that residual PAHs following ENA (presumably non-bioavailable to bioremediation) may still be bioavailable to important receptor organisms such as earthworms and plants.
Publisher: Springer Science and Business Media LLC
Date: 04-02-2012
DOI: 10.1007/S11356-012-0766-7
Abstract: Biowastes produced by humans and animals are routinely disposed of on land, and concern is now growing that such practices provide a pathway for fluoroquinolone (FQs) antibacterial agents and their environmental metabolites (FQEMs) to contaminate the terrestrial environment. The focus of concern is that FQs and FQEMs may accumulate in amended soils to then adversely impact on the terrestrial environment. One postulated impact is the development of a selective environment in which FQ-resistant bacteria may grow. To find evidence in support of an accumulation of antibacterial-like activity, it was first necessary to establish whether any biologically active FQEMs could be synthesized by physicochemical factors that are normally present in the environment. However, many FQEMs are not commercially available to be used as standards in such studies. FQEMs were therefore synthesized using well-defined processes. They were subsequently analyzed using spectroscopy (UV-vis) and high performance liquid chromatography with mass spectral detection. The antibacterial-like activities of fractionated FQEMs were then assessed in novel bacterial growth inhibition bioassays, and results were compared to those obtained from instrumental analyses. Parent FQs were either exposed to sunlight or were synthesized using defined aerobic microbial (Mycobacterium gilvum or a mixed culture derived from an agricultural soil) fermentation processes. Mixtures of FQEMs derived from photo- and (intracellular) microbial processes were isolated by preparative chromatography and centrifugation techniques, respectively. Mixtures were subsequently fractionated using analytical high-performance thin layer chromatography (HPTLC), and excised analytes were tested in bioautography assays for their antibacterial-like activities. Two bacteria, Escherichia coli (E. coli) and Azospirillum brasilense (A. brasilense) were used as reporter organisms in testing FQ standards and any subtle differences between biologically active FQEMs of ciprofloxacin (CF). FQEMs produced in the photo-synthetic process had UV-vis profiles that were indistinguishable from the parent FQs, and yet mass spectral data revealed the presence of N-formylciprofloxacin (FCF). In contrast, the UV-vis profiles of FQEMs synthesized by M. gilvum and a mixed culture of microorganisms had UV-vis profiles that were similar to one another and markedly different to the parent fluoroquinolones. Mass spectral studies confirmed the presence of FCF and N-acetylciprofloxacin in both microbial ferments. In addition, a photo-FQEM (Cp 6), three M. gilvum FQEMs (Cm 5, Cm 8, and Cm 10) and a mixed culture FQEM (Cs 6) of CF and many other FQEMs of CF, norfloxacin (NF), and enrofloxacin (EF) were fractionated using HPTLC, although their identities have yet to be confirmed. Differences between bioautography results were obtained when E. coli or A. brasilense were used as reporter organisms. Parent FQs (CF and EF) and the FQEMs of CF (Cp 6, Cm 8, and Cs 6) displayed antibacterial-like activity when using E. coli as the reporter organism. In contrast, A. brasilense was insensitive to parent CF and sensitive to EF and all tested FQEMs of CF. Results are consistent with photo- and microbial processes modifying CF in different ways, with the latter changing the UV-vis chromophores. It can be inferred that a lack of detection of analytes (especially photo-FQEMs) when using UV-vis does not necessarily indicate an absence of analyte. Additionally, similarities between the UV-vis profiles of FQEMs extracted from the (monoculture) M. gilvum and the mixed culture microbial aerobic ferments are consistent with similar processes operating in both ferments. Results of HPTLC and bioautography studies revealed that mixtures of (photo- and microbial) FQEMs could be fractionated into in idual components. Bioactive FQEMs of ciprofloxacin, as a representative FQ, can be synthesized by photo- and microbial processes, and their detection required the use of both instrumental and bioautography analytical techniques. It is likely that such FQEMs will also be present on agricultural land that has been repeatedly amended with FQ-contaminated biosolids. The use of instrumental analytical techniques alone and especially photometric detection techniques will underestimate antibacterial-like activities of FQEMs. Moreover, the extraction technique(s) and the selected toxicological endpoint(s) require careful consideration when assessing bioactivity. It is therefore recommended that instrumental analytical techniques and several bioautography assays be performed concurrently, and bioautography assays should use a variety of reporter organisms. Two types of bacterial growth bioassays are recommended in any assessment of antibacterial-like activity derived from CF (and possibly from other FQs). A standardized E. coli bioassay should be used as a general screening procedure to facilitate intra- and inter-laboratory exchange of data. Additionally, soil-specific (region-specific) growth inhibition bioassays should be undertaken using several species of endemic soil bacteria. It is likely that the two sets of data will be useful in future risk assessment processes.
Publisher: Elsevier BV
Date: 03-2008
DOI: 10.1016/J.CHEMOSPHERE.2007.10.012
Abstract: Arsenic (As) contamination of soil poses a potential threat to human health, particularly for small children, through the incidental ingestion of soil from hand-to-mouth activity. In this study, we examined the relationship between As bioaccessibility using the simplified bioaccessibility extraction test (SBET) and the soil fractions that contribute to bioaccessible As in 12 long-term contaminated soils. Sequential fractionation of soils prior to As bioaccessibility assessment found that As was primarily associated with the specifically sorbed (3-26%), amorphous and poorly crystalline (12-82%), and the well crystalline (3-25%) oxyhydroxide Fe/Al phases with proportions varying depending on the mode of As input. Arsenic bioaccessibility in these soils ranged from less than 1% in the gossan soil to 48% in railway corridor soils. Soil fractions contributing to As bioaccessibility were found to be from the non-specifically (<1-11%), the specifically (<1-29%) sorbed and the amorphous and poorly-crystalline (30-93%) oxyhydroxide Fe/Al fractions. Significant correlations (p<0.05) were found between the As bioaccessible fraction and the amorphous and poorly-crystalline oxyhydroxide Fe/Al fractions indicating that this fraction is a key factor influencing As bioaccessibility in many anthropogenically contaminated soils.
Publisher: Springer Science and Business Media LLC
Date: 2003
Publisher: Springer Science and Business Media LLC
Date: 31-12-2009
DOI: 10.1007/S10653-008-9229-Y
Abstract: The bioavailability of arsenic (As) in the soil environment is largely governed by its adsorption-desorption reactions with soil constituents. We have investigated the sorption-desorption behaviour of As in four typical Bangladeshi soils subjected to irrigation with As-contaminated groundwater. The total As content of soils (160 s les) from the Laksham district ranged from 10 mg As kg(-1) soil, indicating the potential availability of As. In soils containing <5 mg As kg(-1), As was not detected in the pore water. A comparison of Bangladeshi soils with strongly weathered long-term As-contaminated soils from Queensland, Australia showed a much greater release of As in water extracts from the Australian soils. However, this was attributed to the much higher loading of As in these Australian soils. The correlation of pore water As with other inorganic ions (P, S) showed a strongly significant (P < 0.001) relationship with P, although there was no significant relationship between As and other inorganic cations, such as Fe and Mn. Batch sorption studies showed an appreciable capacity for both As(V) and As(III) sorption, with As(V) being retained in much greater concentrations than As(III).
Publisher: Elsevier BV
Date: 02-2018
DOI: 10.1016/J.ENVPOL.2017.10.089
Abstract: In vitro assays act as surrogate measurements of relative bioavailability (RBA) for inorganic contaminants. The values derived from these assays are routinely used to refine human health risk assessments (HHRA). Extensive in vitro research has been performed on three major inorganic contaminants As, Cd and Pb. However, the majority of these studies have evaluated the contaminants in idually, even in cases when they are found as co-contaminants. Recently, in vivo studies (animal model) have determined that when the three aforementioned contaminants are present in the same soil matrix, they have the ability to influence each other's in idual bioavailability. Since in vitro assays are used to inform HHRA, this study investigated whether bioaccessibility methods including the Solubility/Bioavailability Research Consortium (SBRC) assay, and physiologically based extraction test (PBET), have the ability to detect interactions between As, Cd and Pb. Using a similar dosing methodology to recently published in vivo studies, spiked aged (12 years) soil was assessed by evaluating contaminant bioaccessibility in idually, in addition to tertiary combinations. In two spiked aged soils (grey and brown chromosols), there was no influence on contaminant bioaccessibility when As, Cd and Pb we present as co-contaminants. However, in a red ferrosol, the presence of As and Pb significantly decreased (p < 0.05) the bioaccessibility of Cd when assessed using gastric and intestinal phases of the SBRC assay and the PBET. Conceivable, differences in key physico-chemical properties (TOC, Fe, Al, P) between the study soils influenced contaminant interactions and bioaccessibility outcomes. Although bioaccessibility methods may not account for interactions between elements as demonstrated in in vivo models, in vitro assessment provides a conservative prediction of contaminant RBA under co-contaminant scenarios.
Publisher: Elsevier BV
Date: 08-2018
Publisher: Elsevier BV
Date: 10-2013
Publisher: Elsevier BV
Date: 10-2007
DOI: 10.1016/J.CHEMOSPHERE.2007.05.018
Abstract: An in vivo swine assay was utilised for the determination of arsenic (As) bioavailability in contaminated soils. Arsenic bioavailability was assessed using pharmacokinetic analysis encompassing area under the blood plasma-As concentration time curve following zero correction and dose normalisation. In contaminated soil studies, As uptake into systemic circulation was compared to an arsenate oral dose and expressed as relative As bioavailability. Arsenic bioavailability ranged from 6.9+/-5.0% to 74.7+/-11.2% in 12 contaminated soils collected from former railway corridors, dip sites, mine sites and naturally elevated gossan soils. Arsenic bioavailability was generally low in the gossan soils and highest in the railway soils, ranging from 12.1+/-8.5% to 16.4+/-9.1% and 11.2+/-4.7% to 74.7+/-11.2%, respectively. Comparison of in vivo and in vitro (Simplified Bioaccessibility Extraction Test [SBET]) data from the 12 contaminated soils and bioavailability data collected from an As spiked soil study demonstrated that As bioavailability and As bioaccessibility were linearly correlated (in vivo As bioavailability (mgkg(-1))=14.19+0.93.SBET As bioaccessibility (mgkg(-1)) r(2)=0.92). The correlation between the two methods indicates that As bioavailability (in vivo) may be estimated using the less expensive, rapid in vitro chemical extraction method (SBET) to predict As exposure in human health risk assessment.
Publisher: Elsevier BV
Date: 07-2009
DOI: 10.1016/J.CHEMOSPHERE.2009.03.010
Abstract: The consumption of arsenic (As) contaminated rice is an important exposure route for humans in countries where rice cultivation employs As contaminated irrigation water. Arsenic toxicity and mobility are a function of its chemical-speciation. The distribution and identification of As in the rice plant are hence necessary to determine the uptake, transformation and potential risk posed by As contaminated rice. In this study we report on the distribution and chemical-speciation of As in rice (Oryza sativa Quest) by X-ray fluorescence (XRF) and X-ray absorption near edge structure (XANES) measurements of rice plants grown in As contaminated paddy water. Investigations of muXRF images from rice tissues found that As was present in all rice tissues, and its presence correlated with the presence of iron at the root surface and copper in the rice leaf. X-ray absorption near edge structure analysis of rice tissues identified that inorganic As was the predominant form of As in all rice tissues studied, and that arsenite became increasingly dominant in the aerial portion of the rice plant.
Publisher: Springer Science and Business Media LLC
Date: 18-02-2009
DOI: 10.1007/S10653-009-9249-2
Abstract: Incidental soil ingestion is a common contaminant exposure pathway for humans, notably children. It is widely accepted that the inclusion of total soil metal concentrations greatly overestimates the risk through soil ingestion for people due to contaminant bioavailability constraints. The assumption also assumes that the contaminant distribution and the bioaccessible fraction is consistent across all particle sizes. In this study, we investigated the distribution of arsenic across five particle size fractions as well as arsenic bioaccessibility in the <250-, <100-, <10- and 2.5-microm soil particle fractions in 50 contaminated soils. The distribution of arsenic was generally uniform across the larger particle size fractions but increased markedly in the <2.5-microm soil particle fraction. The marked increase in arsenic concentration in the <2.5-microm fraction was associated with a marked increase in the iron content. Arsenic bioaccessibility, in contrast, increased with decreasing particle size. The mean arsenic bioaccessibility increased from 25 +/- 16% in the <250-microm soil particle fraction to 42 +/- 23% in the <10-microm soil particle fraction. These results indicate that the assumption of static arsenic bioaccessibility values across particle size fractions should be reconsidered if the ingested material is enriched with small particle fractions such as those found in household dust.
Publisher: Elsevier BV
Date: 03-2008
DOI: 10.1016/J.SCITOTENV.2007.11.023
Abstract: The accumulation of arsenic (As) by rice (Oryza sativa L.) is of great interest considering the dietary intake of rice is potentially a major As exposure pathway in countries where rice is irrigated with As contaminated groundwater. A small scale rice paddy experiment was conducted to evaluate the uptake of As by rice. Arsenic concentrations in rice tissue increased in the order grain<<leaf<stem<<<root with the As concentration in the rice grain, in some cases, exceeding the maximum Australian permissible concentration of 1 mg kg(-1). Speciation of As in rice tissue was performed using a modified protein extraction procedure and trifluoroacetic acid extraction. Whilst higher As recoveries were obtained using trifluoroacetic acid extraction, both methods identified arsenite and arsenate as the major As species present in the root, stem and leaf, however, arsenite and dimethylarsinic acid (DMA) were the major As species identified in the grain. Notably, DMA comprised 85 to 94% of the total As concentration in the grain. The high proportion of organic to inorganic As in the grain has implications on human health risk assessment as inorganic As species are more bioavailable than methylated As species.
Publisher: Elsevier BV
Date: 15-06-2006
DOI: 10.1016/J.SCITOTENV.2005.05.039
Abstract: Elevated concentrations of arsenic (As) have been detected in soils of former railway corridors in South Australia, Australia. Elevated As concentrations resulted from the long-term application of As-based herbicides to control grass growth along former railway corridors. A study of former railway corridors revealed considerable surface (0-10 cm) contamination with As ( 1000 mg As kg-1). The distribution of As in soils was related with particle size fraction and iron (Fe) oxide content. Total As increased markedly with decreasing particle size sand<<silt<clay, with increasing As concentration generally correlated with increasing Fe concentrations (R2=0.57). A sequential fractionation of soils collected from selected sites showed that As was primarily associated with the amorphous and crystalline Fe and Al oxide materials. Solid phase speciation of As-contaminated soil indicated that arsenate (AsV) was the dominant As species present in the soil. However, in some soils, arsenite (AsIII) composed up to 40% of the total As present. The reasons for the presence of AsIII under alkaline and aerobic conditions are unclear.
Publisher: Elsevier BV
Date: 09-2016
DOI: 10.1016/J.ENVPOL.2016.06.025
Abstract: The use of zero-valent iron nanoparticles (nZVI) has been advocated for the remediation of both soils and groundwater. A key parameter affecting nZVI remediation efficacy is the mobility of the particles as this influences the reaction zone where remediation can occur. However, by engineering nZVI particles with increased stability and mobility we may also inadvertently facilitate nZVI-mediated contaminant transport away from the zone of treatment. Previous nZVI mobility studies have often been limited to model systems as the presence of background Fe makes detection and tracking of nZVI in real systems difficult. We overcame this problem by synthesising Fe-59 radiolabelled nZVI. This enabled us to detect and quantify the leaching of nZVI-derived Fe-59 in intact soil cores, including a soil contaminated by Chromated-Copper-Arsenate. Mobility of a commercially available nZVI was also tested. The results showed limited mobility of both nanomaterials <1% of the injected mass was eluted from the columns and most of the radiolabelled nZVI remained in the surface soil layers (the primary treatment zone in this contaminated soil). Nevertheless, the observed breakthrough of contaminants and nZVI occurred simultaneously, indicating that although the quantity transported was low in this case, nZVI does have the potential to co-transport contaminants. These results show that direct injection of nZVI into the surface layers of contaminated soils may be a viable remediation option for soils such as this one, in which the mobility of nZVI below the injection/remediation zone was very limited. This Fe-59 experimental approach can be further extended to test nZVI transport in a wider range of contaminated soil types and textures and using different application methods and rates. The resulting database could then be used to develop and validate modelling of nZVI-facilitated contaminant transport on an in idual soil basis suitable for site specific risk assessment prior to nZVI remediation.
Publisher: American Chemical Society (ACS)
Date: 22-11-2016
Abstract: In this study, the in vitro bioaccessibility (IVBA) of lead (Pb) in phosphate-amended Pb-contaminated soil was assessed using a variety of IVBA assays with an overarching aim of determining whether changes in Pb IVBA were congruent to those observed for Pb relative bioavailability (RBA) determined using an in vivo mouse assay. Amending soil with phosphoric acid or rock phosphate resulted in changes in Pb speciation, however, varying Pb IVBA results were obtained depending on the methodology utilized. In addition, IVBA assays influenced Pb speciation as a consequence of interactions between dissolved Pb and unreacted phosphate arising from the amendment or from assay constituents. When the relationship between Pb RBA and IVBA was assessed, a comparison of treatment effect ratios (Pb RBA or IVBA in treated soil ided by Pb RBA or IVBA for untreated soil) provided the best in vivo-in vitro correlation particular for SBRC (r
Publisher: American Chemical Society (ACS)
Date: 07-06-2010
DOI: 10.1021/ES1006516
Abstract: In this study, cadmium (Cd) relative bioavailability in contaminated (n = 5) and spiked (n = 2) soils was assessed using an in vivo mouse model following administration of feed containing soil or Cd acetate (reference material) over a 15 day exposure period. Cadmium relative bioavailability varied depending on whether the accumulation of Cd in the kidneys, liver, or kidney plus liver was used for relative bioavailability calculations. When kidney plus liver Cd concentrations were used, Cd relative bioavailability ranged from 10.1 to 92.1%. Cadmium relative bioavailability was higher (14.4-115.2%) when kidney Cd concentrations were used, whereas lower values (7.2-76.5%) were derived when liver Cd concentrations were employed in calculations. Following in vivo studies, four in vitro methodologies (SBRC, IVG, PBET, and DIN), encompassing both gastric and intestinal phases, were assessed for their ability to predict Cd relative bioavailability. Pearson correlations demonstrated a strong linear relationship between Cd relative bioavailability and Cd bioaccessibility (0.62-0.91), however, stronger in vivo-in vitro relationships were observed when Cd relative bioavailability was calculated using kidney plus liver Cd concentrations. Whereas all in vitro assays could predict Cd relative bioavailability with varying degrees of confidence (r(2) = 0.348-0.835), large y intercepts were calculated for a number of in vitro assays which is undesirable for in vivo-in vitro predictive models. However, determination of Cd bioaccessibility using the intestinal phase of the PBET assay resulted in a small y intercept (5.14 slope =1.091) and the best estimate of in vivo Cd relative bioavailability (r(2) = 0.835).
Publisher: American Chemical Society (ACS)
Date: 30-05-2014
DOI: 10.1021/ES500994U
Abstract: The effect of phosphate treatment on lead relative bioavailability (Pb RBA) was assessed in three distinct Pb-contaminated soils. Phosphoric acid (PA) or rock phosphate were added to smelter (PP2), nonferrous slag (SH15), and shooting range (SR01) impacted soils at a P:Pb molar ratio of 5:1. In all of the phosphate amended soils, Pb RBA decreased compared to that in untreated soils when assessed using an in vivo mouse model. Treatment effect ratios (i.e., the ratio of Pb RBA in treated soil ided by Pb RBA in untreated soil) ranged from 0.39 to 0.67, 0.48 to 0.90, and 0.03 to 0.19 for PP2, SH15, and SR01, respectively. The decrease in Pb RBA following phosphate amendment was attributed to the formation of poorly soluble Pb phosphates (i.e., chloropyromorphite, hydroxypyromorphite, and Pb phosphate) that were identified by X-ray absorption spectroscopy (XAS). However, a similar decrease in Pb RBA was also observed in untreated soils following the sequential gavage of phosphate amendments. This suggests that in vivo processes may also facilitate the formation of poorly soluble Pb phosphates, which decreases Pb absorption. Furthermore, XAS analysis of PA-treated PP2 indicated further in vivo changes in Pb speciation as it moved through the gastrointestinal tract, which resulted in the transformation of hydroxypyromorphite to chloropyromorphite.
Publisher: Springer Science and Business Media LLC
Date: 2003
Publisher: Springer Science and Business Media LLC
Date: 15-11-2013
Publisher: American Chemical Society (ACS)
Date: 22-02-2012
DOI: 10.1021/ES203030Q
Abstract: In this study, DDTr (DDTr = DDT + DDD + DDE) relative bioavailability in historically contaminated soils (n = 7) was assessed using an in vivo mouse model. Soils or reference materials were administered to mice daily over a 7 day exposure period with bioavailability determined using DDTr accumulation in adipose, kidney, or liver tissues. Depending on the target tissue used for its calculation, some variability in DDTr relative bioavailability was observed however, it did not exceed 25% (range 2-25%). When DDTr bioaccessibility was determined using organic physiologically based extraction test (Org-PBET), unified BARGE method (UBM), and fed organic estimation human simulation test (FOREhST) in vitro assays, bioaccessibility was less than 4% irrespective of the assay utilized and the concentration of DDTr in the contaminated soil. Pearson correlations demonstrate a poor relationship between DDTr relative bioavailability and DDTr bioaccessibility (0.47, 0.38, and 0.28, respectively), illustrating the limitations of the static in vitro methods for predicting the dynamic processes of the mammalian digestive system for this hydrophobic organic contaminant.
Publisher: Elsevier BV
Date: 12-2018
DOI: 10.1016/J.CHEMOSPHERE.2018.08.094
Abstract: Soil contamination with total petroleum hydrocarbons (TPH) is widespread throughout the globe due to the massive production of TPH anthropogenically and its occurrence in the soil. TPH is toxic to beneficial soil organisms and humans and thus has become a serious concern among the public. Traditionally TPH toxicity in the soil is estimated based on chemical fractions and a range of bioassays including plants, invertebrates and microorganisms. There is a large inconsistency among ecotoxicology data using these assays due to the nature of TPH and their weathering. Therefore, in this article, we critically reviewed the weathered conditions of TPH, the potential fate in soil and the bioindicators for the assessment of the ecotoxicity. Based on the current research and the state-of-the-art problem, we also highlighted key recommendations for future research scope for the real-world solution of the ecotoxicological studies of hydrocarbons.
Publisher: Springer Science and Business Media LLC
Date: 2003
Publisher: Elsevier BV
Date: 12-2019
DOI: 10.1016/J.SCITOTENV.2019.134114
Abstract: Ammonia (NH
Publisher: IBIMA Publishing
Date: 06-2011
DOI: 10.5171/2011.781417
Publisher: Elsevier BV
Date: 07-2018
DOI: 10.1016/J.ECOENV.2018.03.006
Abstract: In the ecotoxicological assessment of petroleum hydrocarbon-contaminated soil, microbial community profile is important aspect due to their involvement in soil functions. However, soil physicochemical properties and the inhabiting plants could dictate the microbial composition. A question remains unanswered is, how an integrated approach may be utilized to account for various contrasting soil properties, plant types (reference vs. native) and the nature of the hydrocarbon contamination. In this study, we utilized bacterial DNA profiling techniques to investigate the relationship between soil properties, contaminant and plant species. Results identified that Proteobacteria and Actinobacteria were the most abundant bacteria of the 45 phyla identified in the hydrocarbon-contaminated soil. The bulk and rhizosphere microbiome showed that the contaminated soil originally had quite distinct bacterial communities compared to the artificially contaminated soil (mine soil = 95 genera vs. other soils = 2-29 genera). In these cases, not significantly but the native plant slightly increased bacterial ersity and relative abundance in the same soils. Also, within each site, the bacterial community was significantly altered with the hydrocarbon concentration. In this instance, the influence of the contaminant was strong and also with the soil pH and organic matter. These results would significantly contribute to the novel insights on the molecular technique-based hydrocarbon toxicity assessment and the development of the further integrative approach with other microbial community and their metabolic profile in the contaminated sites.
Publisher: Elsevier BV
Date: 10-2019
Publisher: Elsevier BV
Date: 10-2018
Publisher: Elsevier BV
Date: 08-2007
DOI: 10.1016/J.CHEMOSPHERE.2007.04.046
Abstract: Arsenic (As) bioaccessibility in contaminated soils (n=50) was assessed using the simplified bioaccessibility extraction test (SBET). Soils used in the study were collected from sites where As was used as an herbicide (railway corridor) or pesticide (cattle dip sites), from former gold mines and from highly mineralised locations containing geogenic As sources (gossans). In all but three soils, As bioaccessibility was less than 50% indicating that a significant proportion of the total As concentration may not be available for absorption in the gastrointestinal tract following incidental soil ingestion. When regression models were developed based on soil properties, the descriptive variables best able to describe As bioaccessibility in railway corridor, dip site and mine site soils were total As and total or dithionite-citrate extractable (free) iron (Fe). While As bioaccessibility could be predicted (r(2)=0.955, n=50) in these contaminated soils, As bioaccessibility for gossan soils was a poor fit using linear or multivariate regression analysis.
Publisher: Elsevier BV
Date: 08-2016
DOI: 10.1016/J.JHAZMAT.2016.03.090
Abstract: Mine-impacted materials were collected from Victoria, Australia and categorized into three source materials tailings (n=35), calcinated (n=10) and grey slimes (n=5). Arsenic (As) concentrations in these materials varied over several orders of magnitude (30-47,000mgkg(-1)), with median concentrations of 500, 10,800 and 1500mgkg(-1), respectively. When As bioaccessibility was assessed using the Solubility Bioaccessibility Research Consortium (SBRC) assay, As bioaccessibility ranged between 4 and 90%, with mean gastric phase values of 30%, 49% and 82% for tailings, calcinated and grey slimes, respectively. An analysis of variance (ANOVA) determined that As bioaccessibility was significantly different (P<0.05) between source materials. This was due to differences in As mineralogy, soil particle size as well as the concentration and nature of Fe present. X-ray Absorption Near Edge Structure (XANES) analysis identified arseniosiderite, yukonite, realgar, loellingite and mineral sorbed arsenate species in mine-impacted materials. Despite differences in physicochemical properties, 'mine wastes' are often reported under a generic descriptor. Outcomes from this research highlight that variability in As bioaccessibility can be prescribed to As mineralogy and matrix physicochemical properties, while categorizing s les into sub-groups can provide some notional indication of potential exposure.
Publisher: American Chemical Society (ACS)
Date: 28-06-2011
DOI: 10.1021/ES200653K
Abstract: Lead (Pb) bioaccessibility was assessed using 2 in vitro methods in 12 Pb-contaminated soils and compared to relative Pb bioavailability using an in vivo mouse model. In vitro Pb bioaccessibility, determined using the intestinal phase of the Solubility Bioaccessibility Research Consortium (SBRC) assay, strongly correlated with in vivo relative Pb bioavailability (R(2) = 0.88) following adjustment of Pb dissolution in the intestinal phase with the solubility of Pb acetate at pH 6.5 (i.e., relative Pb bioaccessibility). A strong correlation (R(2) = 0.78) was also observed for the relative bioaccessibility leaching procedure (RBALP), although the method overpredicted in vivo relative Pb bioavailability for soils where values were <40%. Statistical analysis of fit results from X-ray absorption near-edge structure (XANES) data for selected soils (n = 3) showed that Pb was strongly associated with Fe oxyhydroxide minerals or the soil organic fraction prior to in vitro analysis. XANES analysis of Pb speciation during the in vitro procedure demonstrated that Pb associated with Fe minerals and the organic fraction was predominantly solubilized in the gastric phase. However, during the intestinal phase of the in vitro procedure, Pb was strongly associated with formation of ferrihydrite which precipitated due to the pH (6.5) of the SBRC intestinal phase. Soils where Fe dissolution was limited had markedly higher concentrations of Pb in solution and hence exhibited greater relative bioavailability in the mouse model. This data suggests that coexistence of Fe in the intestinal phase plays an important role in reducing Pb bioaccessibility and relative bioavailability.
Publisher: Elsevier BV
Date: 06-2018
DOI: 10.1016/J.SCITOTENV.2018.01.312
Abstract: Ammonia (NH
Publisher: Elsevier BV
Date: 03-2014
DOI: 10.1016/J.SCITOTENV.2013.12.030
Abstract: In vitro bioaccessibility assays are often utilised to determine the potential human exposure to soil contaminants through soil ingestion. Comparative studies have identified inconsistencies in the results obtained with different in vitro assays. In this study we investigated the potential causes for the variability between in vitro assay results using the PBET and SBRC assays to assess As bioaccessibility in 5 brownfield contaminated soils. Total As concentration in the 5 soils ranged from 227 to 807 mg As kg(-1) in the 88% was sorbed to Fe mineral phases) with the remaining As present as beudantite or orpiment mineral phases. Arsenic bioaccessibility varied depending on the in vitro methodology markedly higher values were obtained using the SBRC gastric phase compared to the PBET gastric phase, however, similar As bioaccessibility values were obtained in both the SBRC and PBET intestinal phases. The difference in As bioaccessibility following SBRC and PBET gastric phase extraction appeared to be due to the difference in gastric phase pH (i.e. 1.5 versus 2.5 respectively), however, modifying the PBET gastric phase to pH1.5 (that of the SBRC gastric phase) enhanced As bioaccessibility up to 1.6 fold, but was still markedly lower than SBRC values. Although As bioaccessibility was enhanced, the increase did not occur as a result of the solubilisation of As associated Fe mineral phases suggesting As bioaccessibility may also be strongly influenced by the in vitro assay extractant composition. The extractant composition of the PBET assay incorporates a number of organic acids in addition to pepsin which may inhibit the sorption of As onto iron oxide surfaces, therefore increasing As solubility at the modified (pH1.5) gastric phase pH.
Publisher: Elsevier BV
Date: 10-2015
Publisher: Elsevier BV
Date: 2012
DOI: 10.1016/J.JHAZMAT.2011.11.016
Abstract: People are frequently exposed to combinations of contaminants but there is a paucity of data on the effects of mixed contaminants at low doses. This study investigated the influence of cadmium (Cd) on lead (Pb) accumulation in pregnant and non-pregnant mice following exposure to contaminated soil. Exposure to Pb from contaminated soils increased Pb accumulation in both pregnant and non-pregnant mice compared to unexposed control animals (pregnant and non-pregnant). Lead accumulation in the liver and kidneys of exposure pregnant mice (40 ± 15 mg Pb kg(-1)) was significantly higher (P<0.05) than concentrations detected in control pregnant mice (<1 mg Pb kg(-1)). The presence of Cd in contaminated soil had a major effect on the Pb and Fe accumulation in the kidneys and liver, respectively. This study shows that Pb uptake is mediated by the presence of Cd in the co-contaminated soil and demonstrates that further research is required to investigate the influence of co-contaminants on human exposure at sub-chronic concentrations.
Publisher: Elsevier BV
Date: 03-2014
DOI: 10.1016/J.SCITOTENV.2013.12.031
Abstract: In this study, PAH bioavailability was assessed in creosote-contaminated soil following bioremediation in order to determine potential human health exposure to residual PAHs from incidental soil ingestion. Following 1,000 days of enhanced natural attenuation (ENA), a residual PAH concentration of 871 ± 8 mg kg(-1) (∑16 USEPA priority PAHs in the <250 μm soil particle size fraction) was present in the soil. However, when bioavailability was assessed to elucidate potential human exposure using an in vivo mouse model, the upper-bound estimates of PAH absolute bioavailability were in excess of 65% irrespective of the molecular weight of the PAH. These results indicate that a significant proportion of the residual PAH fraction following ENA may be available for absorption following soil ingestion. In contrast, when PAH bioavailability was estimated redicted using an in vitro surrogate assay (FOREhST assay) and fugacity modelling, PAH bioavailability was up to 2000 times lower compared to measured in vivo values depending on the methodology used.
Publisher: Springer Science and Business Media LLC
Date: 2004
Publisher: Elsevier
Date: 1998
Publisher: American Chemical Society (ACS)
Date: 28-08-2015
Abstract: In this study, previously established arsenic (As) in vivo-in vitro correlations (IVIVC) were assessed for their validity using an independent data set comprising As relative bioavailability (RBA) and bioaccessibility values for 13 herbicide- and mine-impacted soils. The validation process established the correlation between As RBA (swine model) and bioaccessibility (five in vitro assays), determined whether correlations differed significantly from previous relationships and assessed model bias and error. The capacity of in vitro assays to predict As RBA was demonstrated by the strength of IVIVC goodness of fit ranged from 0.53 (DIN-I) to 0.74 (UBM-I). When compared to previous IVIVC (Juhasz et al. Environ. Sci. Technol. 2009 , 43 , 9487 Juhasz et al. J. Hazard. Mater. 2011 , 197 , 161 ), there was no significant difference (P < 0.01) in the slope and y-intercept for IVG-G, UBM-G, and UBM-I indicating the consistency of these assays for predicting As RBA. However, variability in model bias and prediction error was observed with significantly lower (P < 0.01) error determined for IVG-G suggesting that As RBA predictions using IVG-G may be more robust compared to UBM-G and UBM-I. In contrast, differences in the slope and/or y-intercept were observed for SBRC-I, IVG-I, PBET-G, PBET-I, DIN-G, and DIN-I suggesting that these methodologies may not be suitable for predicting As RBA.
Publisher: Oxford University Press (OUP)
Date: 10-2002
Publisher: Springer Science and Business Media LLC
Date: 20-12-2009
DOI: 10.1007/S10653-008-9228-Z
Abstract: The influence of ionic strength, index cations and competing anions on arsenate (As(V)) adsorption-desorption kinetics was studied in an Alfisol soil. A flow-through reactor system similar to that developed by Carski and Sparks (Soil Sci Soc Am J 49:1114-1116, 1985) was constructed for the experiments. Arsenate adsorption kinetics for all the treatments were initially fast with 58-91% of As(V) adsorbed in the first 15 min. Beyond 15 min, As(V) adsorption continued at a slower rate for the observation period of the experiments. Changes in the solution composition had differing effects on the cumulative amount of As(V) adsorbed by the soil. Ionic strength and different index cations had little effect on the amount of As(V) adsorbed, while the presence of phosphate decreased the amount of As(V) adsorbed from 169 to 89 and 177 to 115 g As(V) microg(-1) in 0.03 M sodium nitrate and 0.01 M calcium nitrate, respectively. Considerably less As(V) was desorbed than was adsorbed, with only between 2 to 17% of the adsorbed As(V) desorbed. The presence of phosphate increased the amount of As(V) desorbed by 17%, but other changes in the solution ionic strength or index cation had little effect on the amount of As(V) desorbed.
Publisher: Springer Science and Business Media LLC
Date: 08-10-2016
DOI: 10.1007/S00244-016-0318-0
Abstract: Earthworm toxicity assays contribute to ecological risk assessment and consequently standard toxicological endpoints, such as mortality and reproduction, are regularly estimated. These endpoints are not enough to better understand the mechanism of toxic pollutants. We employed an additional endpoint in the earthworm Eisenia andrei to estimate the pollutant-induced stress. In this study, comet assay was used as an additional endpoint to evaluate the genotoxicity of weathered hydrocarbon contaminated soils containing 520 to 1450 mg hydrocarbons kg
Publisher: Elsevier BV
Date: 05-2008
DOI: 10.1016/J.CHEMOSPHERE.2007.12.021
Abstract: Considerable information is available in the literature regarding the uptake of arsenic (As) from contaminated soil and irrigation water by vegetables. However, few studies have investigated As speciation in these crops while a dearth of information is available on As bioavailability following their consumption. In this study, the concentration and speciation of As in chard, radish, lettuce and mung beans was determined following hydroponic growth of the vegetables using As-contaminated water. In addition, As bioavailability was assessed using an in vivo swine feeding assay. While As concentrations ranged from 3.0 to 84.2mg As kg(-1) (dry weight), only inorganic As (arsenite and arsenate) was detected in the edible portions of the vegetables. When As bioavailability was assessed through monitoring blood plasma As concentrations following swine consumption of As-contaminated vegetables, between 50% and 100% of the administered As dose was absorbed and entered systemic circulation. Arsenic bioavailability decreased in the order mung beans>radish>lettuce=chard.
Publisher: Elsevier BV
Date: 05-2008
DOI: 10.1016/J.CHEMOSPHERE.2007.12.022
Abstract: Arsenic (As) bioavailability in spiked soils aged for up to 12 months was assessed using in vitro and in vivo methodologies. Ageing (natural attenuation) of spiked soils resulted in a decline in in vivo As bioavailability (swine assay) of over 75% in soil A (Red Ferrosol) but had no significant effect on in vivo As bioavailability even after 12 months of ageing in soil B (Brown Chromosol). Sequential fractionation, however, indicated that there was repartitioning of As within the soil fractions extracted during the time course investigated. In soil A, the As fraction associated with the more weakly bound soil fractions decreased while the residual fraction increased from 12% to 35%. In contrast, little repartitioning of As was observed in soil B indicating that natural attenuation may be only applicable for As in soils containing specific mineralogical properties.
Publisher: Institute of Electrical and Electronics Engineers (IEEE)
Date: 09-2015
DOI: 10.1109/MIC.2015.107
No related grants have been discovered for Euan Smith.