ORCID Profile
0000-0003-0006-5675
Current Organisation
US Geological Survey
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Publisher: US Geological Survey
Date: 2006
DOI: 10.3133/OFR20061207
Publisher: US Geological Survey
Date: 2003
DOI: 10.3133/OFR0369
Publisher: US Geological Survey
Date: 2009
DOI: 10.3133/SIR20095189
Publisher: Elsevier BV
Date: 06-2021
Publisher: American Association for the Advancement of Science (AAAS)
Date: 15-04-2022
Abstract: Neonicotinoid mixtures are common in streams worldwide, but corresponding ecological responses are poorly understood. We combined experimental and observational studies to narrow this knowledge gap. The mesocosm experiment determined that concentrations of the neonicotinoids imidacloprid and clothianidin (range of exposures, 0 to 11.9 μg/liter) above the hazard concentration for 5% of species (0.017 and 0.010 μg/liter, respectively) caused a loss in taxa abundance and richness, disrupted adult emergence, and altered trophodynamics, while mixtures of the two neonicotinoids caused dose-dependent synergistic effects. In 85 Coastal California streams, neonicotinoids were commonly detected [59% of s les ( n = 340), 72% of streams], frequently occurred as mixtures (56% of streams), and potential toxicity was dominated by imidacloprid (maximum = 1.92 μg/liter) and clothianidin (maximum = 2.51 μg/liter). Ecological responses in the field were consistent with the synergistic effects observed in the mesocosm experiment, indicating that neonicotinoid mixtures pose greater than expected risks to stream health.
Publisher: US Geological Survey
Date: 2014
DOI: 10.3133/DS811
Publisher: Wiley
Date: 05-2008
DOI: 10.2134/JEQ2007.0245
Abstract: Pesticide leaching through variably thick soils beneath agricultural fields in Morgan Creek, Maryland was simulated for water years 1995 to 2004 using LEACHM (Leaching Estimation and Chemistry Model). Fifteen in idual models were constructed to simulate five depths and three crop rotations with associated pesticide applications. Unsaturated zone thickness averaged 4.7 m but reached a maximum of 18.7 m. Average annual recharge to ground water decreased from 15.9 to 11.1 cm as the unsaturated zone increased in thickness from 1 to 10 m. These point estimates of recharge are at the lower end of previously published values, which used methods that integrate over larger areas capturing focused recharge in the numerous detention ponds in the watershed. The total amount of applied and leached masses for five parent pesticide compounds and seven metabolites were estimated for the 32-km2 Morgan Creek watershed by associating each hectare to the closest one-dimensional model analog of model depth and crop rotation scenario as determined from land-use surveys. LEACHM parameters were set such that branched, serial, first-order decay of pesticides and metabolites was realistically simulated. Leaching is predicted to be greatest for shallow soils and for persistent compounds with low sorptivity. Based on simulation results, percent parent compounds leached within the watershed can be described by a regression model of the form e(-depth) (a ln t1/2-b ln K OC) where t1/2 is the degradation half-life in aerobic soils, K OC is the organic carbon normalized sorption coefficient, and a and b are fitted coefficients (R2 = 0.86, p value = 7 x 10(-9)).
Publisher: Springer Science and Business Media LLC
Date: 09-10-2010
Publisher: US Geological Survey
Date: 1995
DOI: 10.3133/OFR95181
Publisher: Wiley
Date: 05-2008
DOI: 10.2134/JEQ2007.0166
Abstract: Occurrence and fate of 45 pesticides and 40 pesticide degradates were investigated in four contrasting agricultural settings--in Maryland, Nebraska, California, and Washington. Primary crops included corn at all sites, soybeans in Maryland, orchards in California and Washington, and vineyards in Washington. Pesticides and pesticide degradates detected in water s les from all four areas were predominantly from two classes of herbicides--triazines and chloroacetanilides insecticides and fungicides were not present in the shallow ground water. In most s les, pesticide degradates greatly exceeded the concentrations of parent pesticide. In s les from Nebraska, the parent pesticide atrazine [6-chloro-N-ethyl-N'-(1-methylethyl)-1,3,5-triazine-2,4-diamine] was about the same concentration as the degradate, but in s les from Maryland and California atrazine concentrations were substantially smaller than its degradate. Simazine [6-chloro-N,N'-diethyl-1,3,5-triazine-2,4-diamine], the second most detected triazine, was detected in ground water from Maryland, California, and Washington. Metolachlor [2-chloro-N-(2-ethyl-6-methylphenyl)-N-(2-methoxy-1-methylethyl)acetamide] rarely was detected without its degradates, and when they were detected in the same s le metolachlor always had smaller concentrations. The Root-Zone Water-Quality Model was used to examine the occurrence and fate of metolachlor at the Maryland site. Simulations accurately predicted which metolachlor degradate would be predominant in the unsaturated zone. In analyses of relations among redox indicators and pesticide variance, apparent age, concentrations of dissolved oxygen, and excess nitrogen gas (from denitrification) were important indicators of the presence and concentration of pesticides in these ground water systems.
Publisher: Elsevier BV
Date: 02-1984
Publisher: Wiley
Date: 05-2008
DOI: 10.2134/JEQ2007.0408
Abstract: Agricultural chemical transport to surface water and the linkage to other hydrological compartments, principally ground water, was investigated at five watersheds in semiarid to humid climatic settings. Chemical transport was affected by storm water runoff, soil drainage, irrigation, and how streams were linked to shallow ground water systems. Irrigation practices and timing of chemical use greatly affected nutrient and pesticide transport in the semiarid basins. Irrigation with imported water tended to increase ground water and chemical transport, whereas the use of locally pumped irrigation water may eliminate connections between streams and ground water, resulting in lower annual loads. Drainage pathways in humid environments are important because the loads may be transported in tile drains, or through varying combinations of ground water discharge, and overland flow. In most cases, overland flow contributed the greatest loads, but a significant portion of the annual load of nitrate and some pesticide degradates can be transported under base-flow conditions. The highest basin yields for nitrate were measured in a semiarid irrigated system that used imported water and in a stream dominated by tile drainage in a humid environment. Pesticide loads, as a percent of actual use (LAPU), showed the effects of climate and geohydrologic conditions. The LAPU values in the semiarid study basin in Washington were generally low because most of the load was transported in ground water discharge to the stream. When herbicides are applied during the rainy season in a semiarid setting, such as simazine in the California basin, LAPU values are similar to those in the Midwest basins.
Publisher: American Chemical Society (ACS)
Date: 13-12-2005
DOI: 10.1021/ES051270Q
Abstract: Identifying the sources and impacts of organic and inorganic contaminants at the watershed scale is a complex challenge because of the multitude of processes occurring in time and space. Investigation of geochemical transformations requires a systematic evaluation of hydrologic, landscape, and anthropogenic factors. The 1160 km2 Boulder Creek Watershed in the Colorado Front Range encompasses a gradient of geology, ecotypes, climate, and urbanization. Streamflow originates primarily as snowmelt and shows substantial annual variation. Water s les were collected along a 70-km transect during spring-runoff and base-flow conditions, and analyzed for major elements, trace elements, bulk organics, organic wastewater contaminants (OWCs), and pesticides. Major-element and trace-element concentrations were low in the headwaters, increased through the urban corridor, and had a step increase downstream from the first major wastewater treatment plant (WWTP). Boron, gadolinium, and lithium were useful inorganic tracers of anthropogenic inputs. Effluent from the WWTP accounted for as much as 75% of the flow in Boulder Creek and was the largest chemical input. Under both hydrological conditions, OWCs and pesticides were detected in Boulder Creek downstream from the WWTP outfall as well as in the headwater region, and loads of anthropogenic-derived contaminants increased as basin population density increased. This report documents a suite of potential endocrine-disrupting chemicals in a reach of stream with native fish populations showing indication of endocrine disruption.
Publisher: Elsevier BV
Date: 02-2022
DOI: 10.1016/J.SCITOTENV.2021.150683
Abstract: Pesticides are widely recognized as important biological stressors in streams, especially in heavily developed urban and agricultural areas like the Central California Coast region. We assessed occurrence and potential toxicity of pesticides in small streams in the region using two analytical methods: a broad-spectrum (223 compounds) method in use since 2012 and a newly developed method for 30 additional new-generation fungicides and insecticides. At least one pesticide compound was identified in 83 of the 85 streams s led. About one-half (48%) of the 253 pesticides measured were detected at least once and 27 were detected in 10% or more of s les. Three of the top 4, and 6 of the top 10 most frequently detected compounds (chlorantraniliprole, dinotefuran, boscalid, thiamethoxam, clothianidin and the fluopicolide degradate 2,6-dichlorobenzamide) were analyzed by the new method. Pesticide mixtures were common, with two or more pesticide compounds detected in 81% of s les and 10 or more in 32% of s les. The pesticide count at a site was relatively consistent over the 6-week study. Four sites with mixed land-use in the lower basin (<5 km from the s ling site) tended to have the highest pesticide counts and the highest concentrations. Potential toxicity (assessed by comparison to benchmarks) to invertebrates was much more common than potential toxicity to fish or plants and was associated with a wide array of insecticides. The common occurrence of new-generation pesticides highlights the need to continuously update analytical methods to keep pace with changing pesticide use for a fuller assessment of pesticide occurrence and effects on the environment.
Publisher: Elsevier BV
Date: 1985
Publisher: Springer Science and Business Media LLC
Date: 10-1987
DOI: 10.1007/BF00301380
Publisher: US Geological Survey
Date: 2008
DOI: 10.3133/OFR20081226
Publisher: US Geological Survey
Date: 2020
DOI: 10.3133/SIR20205072
Publisher: Wiley
Date: 27-02-2018
Publisher: Elsevier BV
Date: 03-1987
Publisher: Elsevier BV
Date: 2017
DOI: 10.1016/J.ENVPOL.2016.09.085
Abstract: The Midwest United States is an intensely agricultural region where pesticides in streams pose risks to aquatic biota, but temporal variability in pesticide concentrations makes characterization of their exposure to organisms challenging. To compensate for the effects of temporal variability, we deployed polar organic chemical integrative s lers (POCIS) in 100 small streams across the Midwest for about 5 weeks during summer 2013 and analyzed the extracts for 227 pesticide compounds. Analysis of water s les collected weekly for pesticides during POCIS deployment allowed for comparison of POCIS results with periodic water-s ling results. The median number of pesticides detected in POCIS extracts was 62, and 141 compounds were detected at least once, indicating a high level of pesticide contamination of streams in the region. Sixty-five of the 141 compounds detected were pesticide degradates. Mean water concentrations estimated using published POCIS s ling rates strongly correlated with means of weekly water s les collected concurrently, however, the POCIS-estimated concentrations generally were lower than the measured water concentrations. Summed herbicide concentrations (units of ng/POCIS) were greater at agricultural sites than at urban sites but summed concentrations of insecticides and fungicides were greater at urban sites. Consistent with these differences, summed concentrations of herbicides correlate to percent cultivated crops in the watersheds and summed concentrations of insecticides and fungicides correlate to percent urban land use. With the exception of malathion concentrations at nine sites, POCIS-estimated water concentrations of pesticides were lower than aquatic-life benchmarks. The POCIS provide an alternative approach to traditional water s ling for characterizing chronic exposure to pesticides in streams across the Midwest region.
Publisher: US Geological Survey
Date: 1995
DOI: 10.3133/FS21995
Publisher: US Geological Survey
Date: 2002
DOI: 10.3133/OFR02462
Publisher: Geological Society of America
Date: 1979
Publisher: Elsevier BV
Date: 05-2006
Publisher: US Geological Survey
Date: 2000
DOI: 10.3133/WRI034045
Publisher: Elsevier BV
Date: 1988
Publisher: Elsevier BV
Date: 2013
DOI: 10.1016/J.SCITOTENV.2012.09.063
Abstract: The Potomac River basin is an area where a high prevalence of abnormalities such as testicular oocytes (TO), skin lesions, and mortality has been observed in smallmouth bass (SMB, Micropterus dolomieu). Previous research documented a variety of chemicals in regional streams, implicating chemical exposure as one plausible explanation for these biological effects. Six stream sites in the Potomac basin (and one out-of-basin reference site) were s led to provide an assessment of chemicals in these streams. Potential early life-stage exposure to chemicals detected was assessed by collecting s les in and around SMB nesting areas. Target chemicals included those known to be associated with important agricultural and municipal wastewater sources in the Potomac basin. The prevalence and severity of TO in SMB were also measured to determine potential relations between chemistry and biological effects. A total of 39 chemicals were detected at least once in the discrete-water s les, with atrazine, caffeine, deethylatrazine, simazine, and iso-chlorotetracycline being most frequently detected. Of the most frequently detected chemicals, only caffeine was detected in water from the reference site. No biogenic hormones/sterols were detected in the discrete-water s les. In contrast, 100 chemicals (including six biogenic hormones/sterols) were found in a least one passive-water s le, with 25 being detected at all such s les. In addition, 46 chemicals (including seven biogenic hormones/sterols) were found in the bed-sediment s les, with caffeine, cholesterol, indole, para-cresol, and sitosterol detected in all such s les. The number of herbicides detected in discrete-water s les per site had a significant positive relation to TO(rank) (a nonparametric indicator of TO), with significant positive relations between TO(rank) and atrazine concentrations in discrete-water s les and to total hormone/sterol concentration in bed-sediment s les. Such significant correlations do not necessarily imply causation, as these chemical compositions and concentrations likely do not adequately reflect total SMB exposure history, particularly during critical life stages.
Publisher: Elsevier BV
Date: 10-2007
DOI: 10.1016/J.SCITOTENV.2007.05.036
Abstract: DEET (N,N-diethyl-m-toluamide) is the active ingredient of most commercial insect repellents. This compound has commonly been detected in aquatic water s les from around the world indicating that DEET is both mobile and persistent, despite earlier assumptions that DEET was unlikely to enter aquatic ecosystems. DEET's registration category does not require an ecological risk assessment, thus information on the ecological toxicity of DEET is sparse. This paper reviews the presence of DEET in aqueous s les from around the world (e.g. drinking water, streams, open seawater, groundwater and treated effluent) with reported DEET concentrations ranging from 40-3000 ng L(-1). In addition, new DEET data collected from 36 sites in coastal waterways from eastern Australia (detections ranging from 8 to 1500 ng L(-1)) are examined. A summary of new and existing toxicity data are discussed with an emphasis on preparing a preliminary risk assessment for DEET in the aquatic environment. Collated information on DEET in the aquatic environment suggests risk to aquatic biota at observed environmental concentrations is minimal. However, the information available was not sufficient to conduct a full risk assessment due to data deficiencies in source characterisation, transport mechanisms, fate, and ecotoxicity studies. These risks warrant further investigation due to the high frequency that this organic contaminant is detected in aquatic environments around the world.
Publisher: US Geological Survey
Date: 2017
DOI: 10.3133/SIR20175049
Publisher: Elsevier BV
Date: 03-1988
Publisher: US Geological Survey
Date: 2018
DOI: 10.3133/SIR20185007
Publisher: US Geological Survey
Date: 2011
DOI: 10.3133/OFR20111054
Publisher: US Geological Survey
Date: 2019
DOI: 10.3133/SIR20195055
Publisher: Elsevier BV
Date: 09-1995
Publisher: American Chemical Society (ACS)
Date: 30-12-2021
Publisher: American Association for the Advancement of Science (AAAS)
Date: 23-10-2020
Abstract: Study shows that a common insecticide frequently detected in U.S. streams is more toxic than previously thought.
Publisher: US Geological Survey
Date: 2016
DOI: 10.3133/TM5B11
Publisher: US Geological Survey
Date: 2016
DOI: 10.3133/TM5B12
Publisher: Wiley
Date: 05-2008
DOI: 10.2134/JEQ2007.0024
Abstract: Pesticide transport through the unsaturated zone is a function of chemical and soil characteristics, application, and water recharge rate. The fate and transport of 82 pesticides and degradates were investigated at five different agricultural sites. Atrazine and metolachlor, as well as several of the degradates of atrazine, metolachlor, acetochlor, and alachlor, were frequently detected in soil water during the 2004 growing season, and degradates were generally more abundant than parent compounds. Metolachlor and atrazine were applied at a Nebraska site the same year as s ling, and focused recharge coupled with the short time since application resulted in their movement in the unsaturated zone 9 m below the surface. At other sites where the herbicides were applied 1 to 2 yr before s ling, only degradates were found in soil water. Transformations of herbicides were evident with depth and during the 4-mo s ling time and reflected the faster degradation of metolachlor oxanilic acid and persistence of metolachor ethanesulfonic acid. The fraction of metolachlor ethanesulfonic acid relative to metolachlor and metolachlor oxanilic acid increased from 0.3 to >0.9 at a site in Maryland where the unsaturated zone was 5 m deep and from 0.3 to 0.5 at the shallowest depth. The flux of pesticide degradates from the deepest sites to the shallow ground water was greatest (3.0-4.9 micromol m(-2) yr(-1)) where upland recharge or focused flow moved the most water through the unsaturated zone. Flux estimates based on estimated recharge rates and measured concentrations were in agreement with fluxes estimated using an unsaturated-zone computer model (LEACHM).
Publisher: Elsevier BV
Date: 1980
Publisher: Elsevier BV
Date: 03-1986
Publisher: American Chemical Society (ACS)
Date: 11-02-2013
DOI: 10.1021/ES303720G
Abstract: Natural and synthetic organic contaminants in municipal wastewater treatment plant (WWTP) effluents can cause ecosystem impacts, raising concerns about their persistence in receiving streams. In this study, Lagrangian s ling, in which the same approximate parcel of water is tracked as it moves downstream, was conducted at Boulder Creek, Colorado and Fourmile Creek, Iowa to determine in-stream transport and attenuation of organic contaminants discharged from two secondary WWTPs. Similar stream reaches were evaluated, and s les were collected at multiple sites during summer and spring hydrologic conditions. Travel times to the most downstream (7.4 km) site in Boulder Creek were 6.2 h during the summer and 9.3 h during the spring, and to the Fourmile Creek 8.4 km downstream site times were 18 and 8.8 h, respectively. Discharge was measured at each site, and integrated composite s les were collected and analyzed for >200 organic contaminants including metal complexing agents, nonionic surfactant degradates, personal care products, pharmaceuticals, steroidal hormones, and pesticides. The highest concentration (>100 μg L(-1)) compounds detected in both WWTP effluents were ethylenediaminetetraacetic acid and 4-nonylphenolethoxycarboxylate oligomers, both of which persisted for at least 7 km downstream from the WWTPs. Concentrations of pharmaceuticals were lower (<1 μg L(-1)), and several compounds, including carbamazepine and sulfamethoxazole, were detected throughout the study reaches. After accounting for in-stream dilution, a complex mixture of contaminants showed little attenuation and was persistent in the receiving streams at concentrations with potential ecosystem implications.
Publisher: Elsevier BV
Date: 05-2020
Publisher: US Geological Survey
Date: 2015
DOI: 10.3133/TM4C4
Publisher: US Geological Survey
Date: 1992
DOI: 10.3133/OFR91519
Publisher: Elsevier BV
Date: 03-2013
DOI: 10.1016/J.SCITOTENV.2013.01.021
Abstract: To document the environmental occurrence and persistence of fungicides, a robust and sensitive analytical method was used to measure 34 fungicides and an additional 57 current-use pesticides in bed sediments and suspended solids collected from areas of intense fungicide use within three geographic areas across the United States. S ling sites were selected near or within agricultural research farms using prophylactic fungicides at rates and types typical of their geographic location. At least two fungicides were detected in 55% of the bed and 83% of the suspended solid s les and were detected in conjunction with herbicides and insecticides. Six fungicides were detected in all s les including pyraclostrobin (75%), boscalid (53%), chlorothalonil (41%) and zoxamide (22%). Pyraclostrobin, a strobilurin fungicide, used frequently in the United States on a variety of crops, was detected more frequently than p,p'-DDE, the primary degradate of p,p'-DDT, which is typically one of the most frequently occurring pesticides in sediments collected within highly agricultural areas. Maximum fungicide concentrations in bed sediments and suspended solids were 198 and 56.7 μg/kg dry weight, respectively. There is limited information on the occurrence, fate, and persistence of many fungicides in sediment and the environmental impacts are largely unknown. The results of this study indicate the importance of documenting the persistence of fungicides in the environment and the need for a better understanding of off-site transport mechanisms, particularly in areas where crops are grown that require frequent treatments to prevent fungal diseases.
Publisher: Elsevier BV
Date: 02-2018
DOI: 10.1016/J.SCITOTENV.2017.06.156
Abstract: Aquatic organisms in streams are exposed to pesticide mixtures that vary in composition over time in response to changes in flow conditions, pesticide inputs to the stream, and pesticide fate and degradation within the stream. To characterize mixtures of dissolved-phase pesticides and degradates in Midwestern streams, a synoptic study was conducted at 100 streams during May-August 2013. In weekly water s les, 94 pesticides and 89 degradates were detected, with a median of 25 compounds detected per s le and 54 detected per site. In a screening-level assessment using aquatic-life benchmarks and the Pesticide Toxicity Index (PTI), potential effects on fish were unlikely in most streams. For invertebrates, potential chronic toxicity was predicted in 53% of streams, punctuated in 12% of streams by acutely toxic exposures. For aquatic plants, acute but likely reversible effects on biomass were predicted in 75% of streams, with potential longer-term effects on plant communities in 9% of streams. Relatively few pesticides in water-atrazine, acetochlor, metolachlor, imidacloprid, fipronil, organophosphate insecticides, and carbendazim-were predicted to be major contributors to potential toxicity. Agricultural streams had the highest potential for effects on plants, especially in May-June, corresponding to high spring-flush herbicide concentrations. Urban streams had higher detection frequencies and concentrations of insecticides and most fungicides than in agricultural streams, and higher potential for invertebrate toxicity, which peaked during July-August. Toxicity-screening predictions for invertebrates were supported by quantile regressions showing significant associations for the Benthic Invertebrate-PTI and imidacloprid concentrations with invertebrate community metrics for MSQA streams, and by mesocosm toxicity testing with imidacloprid showing effects on invertebrate communities at environmentally relevant concentrations. This study documents the most complex pesticide mixtures yet reported in discrete water s les in the U.S. and, using multiple lines of evidence, predicts that pesticides were potentially toxic to nontarget aquatic life in about half of the s led streams.
Publisher: US Geological Survey
Date: 2014
DOI: 10.3133/TM5.2.2.B
Publisher: American Chemical Society (ACS)
Date: 10-03-2021
Publisher: Wiley
Date: 2005
DOI: 10.1897/04-297R.1
Abstract: One of the most frequently detected organic chemicals in a nationwide study concerning the effects of wastewater on stream water quality conducted in the year 2000 was the widely used insect repellant N,N-diethyl-m-toluamide (DEET). It was detected at levels of 0.02 microg/L or greater in 73% of the stream sites s led, with the selection of s ling sites being biased toward streams thought to be subject to wastewater contamination (i.e., downstream from intense urbanization and livestock production). Although DEET frequently was detected at all sites, the median concentration was low (0.05 microg/L). The highest concentrations of DEET were found in streams from the urban areas (maximum concentration, 1.1 microg/L). The results of the present study suggest that the movement of DEET to streams through wastewater-treatment systems is an important mechanism that might lead to the exposure of aquatic organisms to this chemical.
Location: United States of America
Location: United States of America
No related grants have been discovered for Mark Sandstrom.