ORCID Profile
0000-0002-8006-9192
Current Organisations
KU Leuven
,
John Innes Centre
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Publisher: Informa UK Limited
Date: 10-09-2015
DOI: 10.3109/17435390.2014.999139
Abstract: Silver nanoparticles (NPs) are used in more consumer products than any other nanomaterial and their release into the environment is unavoidable. Of primary concern is the wastewater stream in which most silver NPs are transformed to silver sulfide NPs (Ag2S-NPs) before being applied to agricultural soils within biosolids. While Ag2S-NPs are assumed to be biologically inert, nothing is known of their effects on terrestrial plants. The phytotoxicity of Ag and its accumulation was examined in short-term (24 h) and longer-term (2-week) solution culture experiments with cowpea (Vigna unguiculata L. Walp.) and wheat (Triticum aestivum L.) exposed to Ag2S-NPs (0-20 mg Ag L(-1)), metallic Ag-NPs (0-1.6 mg Ag L(-1)), or ionic Ag (AgNO3 0-0.086 mg Ag L(-1)). Although not inducing any effects during 24-h exposure, Ag2S-NPs reduced growth by up to 52% over a 2-week period. This toxicity did not result from their dissolution and release of toxic Ag(+) in the rooting medium, with soluble Ag concentrations remaining below 0.001 mg Ag L(-1). Rather, Ag accumulated as Ag2S in the root and shoot tissues when plants were exposed to Ag2S-NPs, consistent with their direct uptake. Importantly, this differed from the form of Ag present in tissues of plants exposed to AgNO3. For the first time, our findings have shown that Ag2S-NPs exert toxic effects through their direct accumulation in terrestrial plant tissues. These findings need to be considered to ensure high yield of food crops, and to avoid increasing Ag in the food chain.
Publisher: Scientific Research Publishing, Inc.
Date: 2013
Publisher: Elsevier BV
Date: 03-2011
DOI: 10.1016/J.ENVPOL.2010.11.009
Abstract: Long-term applications of small concentrations of surfactants in soil via wastewater irrigation or pesticide application may enhance trace metal solubility. Mechanisms by which anionic surfactants (Aerosol 22, SDS and Biopower) affect trace metal solubility were assessed using batch, incubation and column experiments. In batch experiments on seven soils, the concentrations of Cu, Cd, Ni and Zn in the dissolved fraction of soils increased up to 100-fold at the high application rates, but increased less than 1.5-fold below the critical micelle concentration. Dissolved metal concentrations were less than 20% affected by surfactants in long-term incubations (70 days) up to the largest dose of 200 mg C kg(-1) soil. Leaching soil columns with A22 (100-1000 mg C L(-1)) under unsaturated conditions increased trace metal concentrations in the leachates 2-4 fold over the control. Correlation analysis and speciation modelling showed that the increased solubility of metals upon surfactant application was more related to the solubilisation of soil organic matter from soil than to complexation of the metals with the surfactant. Organic matter from soil was solubilised in response to a decrease of solution Ca(2+) as a result of Ca-surfactant precipitation. At environmentally relevant concentrations, surfactant application is unlikely to have a significant effect on trace metal mobility.
Publisher: Elsevier BV
Date: 03-2016
DOI: 10.1016/J.SCITOTENV.2015.12.107
Abstract: Biochar sequesters carbon (C) in soils because of its prolonged residence time, ranging from several years to millennia. In addition, biochar can promote indirect C-sequestration by increasing crop yield while, potentially, reducing C-mineralization. This laboratory study was set up to evaluate effects of biochar on C-mineralization with due attention to source appointment by using (13)C isotope signatures. An arable soil (S) (7.9 g organic C, OC kg(-1)) was amended (single dose of 10 g kg(-1) soil) with dried, grinded maize stover (leaves and stalks), either natural (R) or (13)C enriched (R*), and/or biochar (B/B*) prepared from the maize stover residues (450 °C). Accordingly, seven different combinations were set up (S, SR, SB, SR*, SB*, SRB*, SR*B) to trace the source of C in CO2 (180 days), dissolved organic-C (115 days) and OC in soil aggregate fractions (90 days). The application of biochar to soil reduced the mineralization of native soil organic C but the effect on maize stover-C mineralization was not consistent. Biochar application decreased the mineralization of the non-enriched maize stover after 90 days, this being consistent with a significant reduction of dissolved organic C concentration from 45 to 18 mg L(-1). However, no significant effect was observed for the enriched maize stover, presumably due to differences between the natural and enriched materials. The combined addition of biochar and enriched maize stover significantly increased (twofold) the presence of native soil organic C or maize derived C in the free microaggregate fraction relative to soil added only with stover. Although consistent effects among C sources and biochar materials remains elusive, our outcomes indicate that some biochar products can reduce mineralization and solubilization of other sources of C while promoting their physical protection in soil particles.
Publisher: Springer Science and Business Media LLC
Date: 13-07-2007
DOI: 10.1007/S00216-007-1418-5
Abstract: The extraction of two pyrethroid insecticides (deltamethrin and alpha-cypermethrin) together with three organophosphorus insecticides (dimethoate, diazinon and malathion) from soil s les was carried out with microwave-assisted technology. Experimental designs showed that extraction temperature, addition of water to the extractant and solvent/soil ratio were the variables that affected the recoveries of the pesticide the most. Response surface methodology was applied to find the optimum values of the variables involved in the extractions of the analytes. In addition, in order to achieve near-optimal extraction conditions, a desirability function was used to optimize the five pesticides simultaneously. The optimized conditions were applied to different types of soils.
Publisher: Springer Science and Business Media LLC
Date: 10-2013
DOI: 10.1007/S10822-013-9686-Y
Abstract: Isoflavone reductase-like proteins (IRLs) are enzymes with key roles in the metabolism of erse flavonoids. Last identified olive pollen allergen (Ole e 12) is an IRL relevant for allergy amelioration, since it exhibits high prevalence among atopic patients. The goals of this study are the characterization of (A) the structural-functionality of Ole e 12 with a focus in its catalytic mechanism, and (B) its molecular allergenicity by extensive analysis using different molecular computer-aided approaches covering (1) physicochemical properties and functional-regulatory motifs, (2) sequence analysis, 2-D and 3D structural homology modeling comparative study and molecular docking, (3) conservational and evolutionary analysis, (4) catalytic mechanism modeling, and (5) sequence, structure-docking based B-cell epitopes prediction, while T-cell epitopes were predicted by inhibitory concentration and binding score methods. Structural-based detailed features, phylogenetic and sequences analysis have identified Ole e 12 as phenylcoumaran benzylic ether reductase. A catalytic mechanism has been proposed for Ole e 12 which display Lys133 as one of the conserved residues of the IRLs catalytic tetrad (Asn-Ser-Tyr-Lys). Structure characterization revealed a conserved protein folding among plants IRLs. However, sequence polymorphism significantly affected residues involved in the catalytic pocket structure and environment (cofactor and substrate interaction-recognition). It might also be responsible for IRLs isoforms functionality and regulation, since micro-heterogeneities affected physicochemical and posttranslational motifs. This polymorphism might have large implications for molecular differences in B- and T-cells epitopes of Ole e 12, and its identification may help designing strategies to improve the component-resolving diagnosis and immunotherapy of pollen and food allergy through development of molecular tools.
Publisher: American Society of Clinical Oncology (ASCO)
Date: 06-2011
Abstract: Prognosis in patients with sentinel node (SN) –positive melanoma correlates with several characteristics of the metastases in the SN such as size and site. These factors reflect biologic behavior and may separate out patients who may or may not need additional locoregional and/or systemic therapy. Between 1993 and 2008, 1,080 patients (509 women and 571 men) were diagnosed with tumor burden in the SN in nine European Organisation for Research and Treatment of Cancer (EORTC) melanoma group centers. In total, 1,009 patients (93%) underwent completion lymph node dissection (CLND). Median Breslow thickness was 3.00 mm. The median follow-up time was 37 months. Tumor load and tumor site were reclassified in all nodes by the Rotterdam criteria for size and in 88% by the Dewar criteria for topography. Patients with submicrometastases ( 0.1 mm in diameter) were shown to have an estimated 5-year overall survival rate of 91% and a low nonsentinel node (NSN) positivity rate of 9%. This is comparable to the rate in SN-negative patients. The strongest predictive parameter for NSN positivity and prognostic parameter for survival was the Rotterdam-Dewar Combined (RDC) criteria. Patients with submicrometastases that were present in the subcapsular area only, had an NSN positivity rate of 2% and an estimated 5- and 10-year melanoma-specific survival (MSS) of 95%. Patients with metastases 0.1 mm, especially when present in the subcapsular area only, may be overtreated by a routine CLND and have an MSS that is indistinguishable from that of SN-negative patients. Thus the RDC criteria provide a rational basis for decision making in the absence of conclusions provided by randomized controlled trials.
Publisher: Oxford University Press (OUP)
Date: 22-09-2015
DOI: 10.1104/PP.15.00726
Publisher: Springer Science and Business Media LLC
Date: 07-07-2010
Publisher: Elsevier BV
Date: 05-2007
DOI: 10.1016/J.SCITOTENV.2007.01.011
Abstract: Pesticides may affect soil quality since they are applied either directly to the soil or transported from the treated crops. Although the soil is able to partially retain environmental contaminants, the use of organic amendments, such as sewage sludge, peat or surfactants, may increase the retention in the upper soil layers, where the contaminants can be degraded and thus diminish their environmental fate. The effect of adding sewage sludge, peat and humic acids, together with a cationic surfactant to the soil, on the adsorption and desorption of organophosphorous insecticides has been studied. The results indicate that humic acids induce an adsorption increment of the pesticides, while peat and sewage sludge do not significantly affect pesticide adsorption at the dosage applied. The use of a cationic surfactant considerably enhances the insecticide retention. The increase was highest for the combined application of the surfactant and the humic acids. Desorption isotherms are inversely related to the adsorption behaviour, being higher for only soil, lower for soil added with carbon-rich amendments, and drastically reduced when the cationic surfactant is present. Concerning the insecticides, adsorption and desorption are related to their physicochemical properties.
Publisher: Wiley
Date: 03-2012
Publisher: InTech
Date: 26-03-2014
DOI: 10.5772/58294
Publisher: Elsevier BV
Date: 10-2007
Publisher: InTech
Date: 25-01-2012
DOI: 10.5772/39117
Publisher: Royal Society of Chemistry (RSC)
Date: 2011
DOI: 10.1039/C1EM10223K
Abstract: Accumulation of metals in soil at elevated concentrations causes risks to the environmental quality and human health for more than one hundred million people globally. The rate of metal release and the alteration of metal distribution in soil phases after soil washing with a sulfosuccinamate surfactant solution (Aerosol 22) were evaluated for four contaminated soils. Furthermore, a sequential extraction scheme was carried out using selective extractants (HAcO, NH(2)OH·HCl, H(2)O(2) + NH(4)AcO) to evaluate which metal species are extracted by A22 and the alteration in metal distribution upon surfactant-washing. Efficiency of A22 to remove metals varied among soils. The washing treatment released up to 50% of Cd, 40% of Cu, 20% of Pb and 12% of Zn, mainly from the soluble and reducible soil fractions, therefore, greatly reducing the fraction of metals readily available in soil. Metal speciation analysis for the solutions collected upon soil washing with Aerosol 22 further confirmed these results. Copper and lead in solution were mostly present as soluble complexes, while Cd and Zn were present as free ions. Besides, redistribution of metals in soil was observed upon washing. The ratios of Zn strongly retained in the soil matrix and Cd complexed with organic ligands increased. Lead was mobilized to more weakly retained forms, which indicates a high bioavailability of the remaining Pb in soil after washing. Comprehensive knowledge on chemical forms of metals present in soil allows a feasible assessment of the environmental impact of metals for a given scenario, as well as possible alteration of environmental conditions, and a valuable prediction for potential leaching and groundwater contamination.
Publisher: Cold Spring Harbor Laboratory
Date: 31-01-2022
DOI: 10.1101/2022.01.28.478001
Abstract: Root phenotyping describes methods for measuring root properties, or traits. While root phenotyping can be challenging, it is advancing quickly. In order for the field to move forward, it is essential to understand the current state and challenges of root phenotyping, as well as the pressing needs of the root biology community. In this letter, we present and discuss the results of a survey that was created and disseminated by members of the Graduate Student and Postdoc Ambassador Program at the 11th symposium of the International Society of Root Research. This survey aimed to (1) provide an overview of the objectives, biological models and methodological approaches used in root phenotyping studies, and (2) identify the main limitations currently faced by plant scientists with regard to root phenotyping. Our survey highlighted that (1) monocotyledonous crops dominate the root phenotyping landscape, (2) root phenotyping is mainly used to quantify morphological and architectural root traits, (3) 2D root scanning/imaging is the most widely used root phenotyping technique, (4) time-consuming tasks are an important barrier to root phenotyping, (5) there is a need for standardised, high-throughput methods to s le and phenotype roots, particularly under field conditions, and to improve our understanding of trait-function relationships.
Publisher: American Chemical Society (ACS)
Date: 17-10-2018
Abstract: The clearing of land for agricultural production depletes soil organic carbon (OC) reservoirs, yet despite their importance, the mechanisms by which C is stabilized in soils remain unclear. Using synchrotron-based infrared microspectroscopy, we have for the first time obtained in situ, laterally resolved data regarding the speciation of C within sections taken from intact free microaggregates from two contrasting soils (Vertisol and Oxisol, 0-20 cm depth) impacted upon by long-term (up to 79 y) agricultural production. There was no apparent gradient in the C concentration from the aggregate surface to the interior for any of the three forms of C examined (aliphatic C, aromatic C, and polysaccharide C). Rather, organo-mineral interactions were of critical importance in influencing overall C stability, particularly for aliphatic C, supporting the hypothesis that microaggregates form through organo-mineral interactions. However, long-term cropping substantially decreased the magnitude of the organo-mineral interactions for all three forms of C. Thus, although organo-mineral interactions are important for OC stability, C forms associated with the mineral phases are not entirely resistant to degradation. These results provide important insights into the underlying mechanisms by which microaggregates form and the factors influencing the persistence of OC in soils.
Publisher: Springer Science and Business Media LLC
Date: 26-04-2016
DOI: 10.1038/SREP25127
Abstract: The use of biochar can contribute to carbon (C) storage in soil. Upon addition of biochar, there is a spatial reorganization of C within soil particles, but the mechanisms remain unclear. Here, we used Fourier transformed infrared-microscopy and confocal laser scanning microscopy to examine this reorganization. A silty-loam soil was amended with three different organic residues and with the biochar produced from these residues and incubated for 237 d. Soil respiration was lower in biochar-amended soils than in residue-amended soils. Fluorescence analysis of the dissolved organic matter revealed that biochar application increased a humic-like fluorescent component, likely associated with biochar-C in solution. The combined spectroscopy-microscopy approach revealed the accumulation of aromatic-C in discrete spots in the solid-phase of microaggregates and its co-localization with clay minerals for soil amended with raw residue or biochar.The co-localization of aromatic-C:polysaccharides-C was consistently reduced upon biochar application. We conclude that reduced C metabolism is an important mechanism for C stabilization in biochar-amended soils.
Publisher: Springer Netherlands
Date: 16-11-2012
Publisher: InTech
Date: 27-02-2013
DOI: 10.5772/55632
Publisher: Elsevier BV
Date: 07-2012
Abstract: This phase III open-label trial investigated the efficacy of nilotinib in patients with advanced gastrointestinal stromal tumors following prior imatinib and sunitinib failure. Patients were randomized 2:1 to nilotinib 400 mg b.i.d. or best supportive care (BSC BSC without tyrosine kinase inhibitor, BSC+imatinib, or BSC+sunitinib). Primary efficacy end point was progression-free survival (PFS) based on blinded central radiology review (CRR). Patients progressing on BSC could cross over to nilotinib. Two hundred and forty-eight patients enrolled. Median PFS was similar between arms (nilotinib 109 days, BSC 111 days P=0.56). Local investigator-based intent-to-treat (ITT) analysis showed a significantly longer median PFS with nilotinib (119 versus 70 days P=0.0007). A trend in longer median overall survival (OS) was noted with nilotinib (332 versus 280 days P=0.29). Post hoc subset analyses in patients with progression and only one prior regimen each of imatinib and sunitinib revealed a significant difference in median OS of >4 months in favor of nilotinib (405 versus 280 days P=0.02). Nilotinib was well tolerated. In the ITT analysis, no significant difference in PFS was observed between treatment arms based on CRR. In the post hoc subset analyses, nilotinib provided significantly longer median OS.
Publisher: Springer Netherlands
Date: 19-11-2012
Publisher: Wiley
Date: 26-03-2015
DOI: 10.1111/GCBB.12250
Publisher: Elsevier BV
Date: 03-2012
DOI: 10.1016/J.JENVMAN.2010.09.025
Abstract: A batch test was used to evaluate the extent of desorption of diazinon and dimethoate, preadsorbed on a calcareous agricultural soil, representative of the Mediterranean area. Urban wastewater from a secondary treatment and seven surfactant solutions, at concentrations ranging from 0.75 mg L(-1) to 10 gL(-1), were used. The surfactants assayed were cationic (hexadecyl trimethyl ammonium bromide (HD)), anionic (sodium dodecyl sulfate (SDS), Aerosol 22 (A22) and Biopower (BP)), and nonionic (Tween 80 (TW), Triton X 100 (TX) and Glucopon 600 (G600)). Desorption of dimethoate was either not affected or only slightly by the nonionic and anionic surfactants tested, while desorption of diazinon from the soil was only enhanced by A22, BP and TW. This desorption increase correlated significantly with the surfactant concentration of the solution used for desorption and with the concurrent increase in the supernatant of the dissolved organic carbon, in particular that originating from the surfactant. This parameter did not vary with the use of SDS, G600 and TX. The cationic surfactant HD was retained on the soil surface, as confirmed by an increase in soil organic carbon, resulting in a fall in desorption rate for both pesticides. Comparing treatment by wastewater with control water, there was no difference in desorption rate for either pesticide. Mixed TW/anionic surfactant solutions either did not modify or slightly increased desorption of both pesticides in comparison with in idual surfactant solutions.
Publisher: Copernicus GmbH
Date: 14-04-2015
Abstract: Abstract. The bioavailability of metals in soil is only partially explained by their partition among the solid and aqueous phase and is more related to the characterization of their speciation in the soil solution. The organic ligands in solution that largely determine metal speciation involve complex mixtures and the characterization of fluorescence components of dissolved organic matter (DOM) can identify pools of molecules that participate in metal speciation, this being essential for risk assessment. The bioavailability of Cd, Cu, Pb and Zn in three agricultural soils was examined in the laboratory to recreate irrigation with greywater enriched in anionic surfactants (Aerosol 22 and Biopower). Field capacity and saturation regimes were considered for this study. Irrigation with aqueous solutions of the anionic surfactants increased total DOM concentrations and metals in the soil solution (Pb Cu Zn Cd). Significant correlation (p 0.05) between the readily available pool of metals with the concentration of DOM was determined for Cu (r = 0.67), Pb (r = 0.82) and Zn (r = 0.68). However, speciation analysis performed with the software WHAM indicated that mobilisation of DOM and metals into the soluble phase resulted in a low concentration of free ion activities and promoted the formation of metal-organo complexes. The characterization of fluorescence components revealed that DOM in soil solution from soils irrigated with Aerosol 22 was enriched in a reduced quinone-like and a humic-like component. Besides, fluorescence quenching provided further evidence of metal complexation with organic ligands in solution. Hence, metal mobilization in soil irrigated with surfactant enriched greywater occurs with solubilisation of high affinity organic ligands, which substantially decreases the potential risk of metal toxicity.
Publisher: Springer Berlin Heidelberg
Date: 2010
Publisher: Wiley
Date: 22-12-2017
DOI: 10.1111/GCB.14009
Abstract: Understanding the cycling of C and N in soils is important for maintaining soil fertility while also decreasing greenhouse gas emissions, but much remains unknown about how organic matter ( OM ) is stabilized in soils. We used nano‐scale secondary ion mass spectrometry (Nano SIMS ) to investigate the changes in C and N in a Vertisol and an Alfisol incubated for 365 days with 13 C and 15 N pulse labeled lucerne ( Medicago sativa L.) to discriminate new inputs of OM from the existing soil OM . We found that almost all OM within the free stable microaggregates of the soil was associated with mineral particles, emphasizing the importance of organo‐mineral interactions for the stabilization of C. Of particular importance, it was also found that 15 N‐rich microbial products originating from decomposition often sorbed directly to mineral surfaces not previously associated with OM . Thus, we have shown that N‐rich microbial products preferentially attach to distinct areas of mineral surfaces compared to C‐dominated moieties, demonstrating the ability of soils to store additional OM in newly formed organo‐mineral associations on previously OM ‐free mineral surfaces. Furthermore, differences in 15 N enrichment were observed between the Vertisol and Alfisol presumably due to differences in mineralogy (smectite‐dominated compared to kaolinite‐dominated), demonstrating the importance of mineralogy in regulating the sorption of microbial products. Overall, our findings have important implications for the fundamental understanding of OM cycling in soils, including the immobilization and storage of N‐rich compounds derived from microbial decomposition and subsequent N mineralization to sustain plant growth.
Publisher: Elsevier BV
Date: 05-2009
DOI: 10.1016/J.WATRES.2009.03.016
Abstract: The simultaneous disappearance of four organophosphorous insecticides in a Mediterranean calcareous soil was evaluated in the presence of surfactant solutions and municipal wastewater. A cationic, an anionic and a non-ionic surfactant were used at a low (0.75 mg L(-1)) and at a high (twice the critical micelle concentration) concentration level. The cationic surfactant was also studied at a higher concentration. Dissipation in control soil was rapid for malathion (half-life 4 days), intermediate for dimethoate and methidathion (ca. 6 days) and slow for diazinon (29 days). Wastewater did either not modify (diazinon, dimethoate and methidathion) or slightly enhance (malathion) insecticide decay. The increase in concentration of the non-ionic surfactant Tween 80 resulted in enhanced dissipation rates for all the pesticides except diazinon. The addition of the anionic surfactant did not show a clear trend. At the highest cationic surfactant concentration a reduction of pesticide disappearance occurred linked with a reduced availability, since the insecticides were retained on the surfactant-modified soil (final residual concentration of 85% for diazinon and approximately 55% for methidathion and dimethoate). Soil microbial activity, estimated by measuring dehydrogenase activity, was low in wastewater- and surfactant-treated soil at the high levels. Fitting of the experimental data to commonly used mathematical models was poor and alternatives were looked for.
Publisher: Springer Science and Business Media LLC
Date: 20-12-2013
Publisher: InTech
Date: 07-03-2012
DOI: 10.5772/38873
Publisher: Elsevier BV
Date: 04-2012
DOI: 10.1016/J.SCITOTENV.2012.02.033
Abstract: The mobility and bioavailability of cadmium, copper, lead and zinc were evaluated in three soils amended with different organic materials for two moisture regimes. Agricultural and reclamation activities impose fresh inputs of organic matter on soil while intensive irrigation and rainstorm increase soil waterlogging incidence. Moreover, scarcity of irrigation water has prompted the use of greywater, which contain variable concentrations of organic compounds such as anionic surfactants. Soils added with hay, maize straw or peat at 1% w/w were irrigated, at field capacity (FC) or saturated (S), with an aqueous solution of the anionic surfactant Aerosol 22 (A22), corresponding to an addition of 200 mgC/kgsoil/day. Soil solution was extracted after one month and analysed for total soluble metals, dissolved soil organic matter and UV absorbance at 254 nm. Speciation analyses were performed with WHAM VI for Cd, Cu, Pb, and Zn. For selected scenarios, metal uptake by barley was determined. Metal mobility increased for all treatments and soils (Pb>Cu>Cd≥Zn) compared to control assays. The increase was significantly correlated (p<0.05) with soil organic matter solubilisation for Cd (R=0.68), Cu (R=0.73) and Zn (R=0.86). Otherwise, Pb release was related to aluminium solubilisation (R=0.75), which suggests that Pb was originally co-precipitated with Al-DOC complexes in the solid phase. The effect of A22 in metal bioavailability, determined as free ion activities (FIA), was mainly controlled by soil moisture regime. For soil 3, metal bioavailability was up to 20 times lower for soil amended with hay, peat or maize compared to soil treated only with A22. When soil was treated with A22 at FC barley yield significantly decreased (p<0.05) for the increase of Pb (R=0.71) and Zn (R=0.79) concentrations in shoot, while for saturated conditions such uptake was up to 3 times lower. Overall, metal bioavailability was controlled by solubilisation of soil organic matter and formation of metal-organo complexes.
Publisher: InTech
Date: 26-03-2014
DOI: 10.5772/58294
Publisher: Wiley
Date: 21-03-2013
DOI: 10.1002/ETC.2159
Abstract: The potential impact of erse inputs of organic matter (hay, maize straw, and peat) on the mobility and bioavailability of Cd, Cu, Pb, and Zn was examined at laboratory scale for three soils with contrasting properties and for two moisture regimes: field capacity and saturated conditions. Soil solution was characterized for total soluble metals, dissolved soil organic carbon, and ultraviolet absorbance at 254 nm. Speciation analyses were performed with WHAM VI. For field capacity conditions, metal mobility increased (Pb>Cu>Zn>Cd) for all soils and treatments compared with controls and was significantly correlated (p<0.05) with dissolved organic matter (r=0.540). Solubilization of organic matter was mostly driven by Al mobilization (r=0.580, p<0.05) and variations in solution pH. The bioavailable pool of metals, estimated as free ion activities, decreased with the increasing occurrence of metal-organic matter complexes, which was accompanied by an increase in solution of highly aromatic organic matter. Soil saturation generally decreased metal mobility and the ratio of metal-organo matter complexes in solution. Consistently, such effects were accompanied by a decrease in the solubilization of organic matter and lower mobilization of Al, Fe, and Mn.
Publisher: Wiley
Date: 07-2010
DOI: 10.2134/JEQ2009.0242
Abstract: Anionic surfactants, mainly sulfosuccinamates, can be found in soils as the result of sludge application, wastewater irrigation, and remediation processes. Relatively high concentrations of surfactants together with multimetals can represent an environmental risk. A study was performed to assess the potential of the anionic surfactant Aerosol 22 (A22) for release of Cd, Cu, Pb, and Zn from a metal-amended soil representative of a Mediterranean area. Metal desorption was performed by batch experiments and release kinetics were assessed. Response surface methodology was applied to determine the influence of A22 concentration and the surfactant/soil ratio, as extraction key factors. An increase in solution/soil ratio to 100 (mL g(-1)) caused higher metal release. Leaching predictions found Pb to have the lowest and Cd the highest hazard. Metal release was highly dependent on pH. When extraction was made at pH less than 7, low or negligible amounts of metals were leached, whereas an increase to pH 7 caused desorption rates of 50 to 55% for Cd, Cu, and Zn but only 35% for Pb. Complexed metal-carboxylic groups from A22 were mainly responsible for its higher extractive capacity, especially of Cd and Cu.
Location: United Kingdom of Great Britain and Northern Ireland
No related grants have been discovered for Maria C. Hernandez-Soriano.