Geology topics

Corey Sanders

Publications and source records attributed to Corey Sanders.

9 recordsLinked to original sources

USGS2025

Effects of flow on pesticides in water and zooplankton in the northern Sacramento-San Joaquin Delta

Zooplankton are a key food source for juvenile fishes in estuaries worldwide, including California’s Sacramento–San Joaquin Delta (hereafter Delta); both zooplankton quality and quantity are critical to ecosystem health. Zooplankton may be affected by pesticides in water and the food web, and the Delta is known to contain complex pesticide mixtures. In this study, we evaluated pesticide concentrations in water and zooplankton in the northern Delta during (1) the summer–fall of 2017, 2018, and 2019, which included periods of augmented pulse flows from agriculture tailwater, and (2) across a full seasonal cycle from May 2019 to March 2020. We quantified changes in pesticide concentration in response to environmental factors. We found that zooplankton showed more frequent detections of hydrophobic pesticides compared to more frequent detections of hydrophilic compounds in water. Pesticide concentrations were influenced by flow, pesticide application, and season, but the effects of these environmental factors differed by habitat (Sacramento River or Yolo Bypass Toe Drain). Pesticides in water responded similarly to environmental factors in the Sacramento River and Yolo Bypass, whereas pesticides in zooplankton responded differently. In water, we found more detections and higher concentrations at higher flows in the Yolo Bypass and Sacramento River, but responses to pesticide application varied by habitat. Alternatively, pesticide concentrations in zooplankton increased in the Yolo Bypass with increasing flow (correlated with flow pulses) and changed seasonally; whereas, pesticide concentrations in zooplankton in the Sacramento River decreased at higher flows, and decreased with or did not respond to higher pesticide application in the watershed. Our study suggests that augmented flows—particularly those using agricultural tailwater—may have unintended negative ecological effects that could partially offset benefits to the food web and fishes in the northern Delta, underscoring the complex interplay among factors that drive increased pesticide exposure.

California↗

USGS2025

Characterizing pyrethroid and fipronil concentrations in biosolids

Pesticides are prevalent in wastewater, yet few studies have measured pesticides in biosolids and aqueous media from samples collected concurrently. Seventeen California wastewater treatment plants (WWTPs) were sampled in May 2020. Biosolids samples were analyzed for 27 analytes, and paired aqueous samples (influent and effluent) were analyzed for 23 analytes. Analytes included fipronil and its transformation products (fiproles), pyrethroids, novaluron, and several other pesticides with down-the-drain transport potential. Of the 27 compounds analyzed in biosolids samples, 16 were detected in at least one sample, and 10 had a detection frequency (DF) of at least 25 %. Fipronil sulfone, fipronil sulfide, and fipronil were the most frequently detected fiproles (DF = 100 %, 94 %, and 67 %, respectively); permethrin was the most frequently detected pyrethroid (DF = 100 %), followed by bifenthrin (DF = 94 %), cyhalothrin (DF = 89 %), and etofenprox (DF = 78 %). To elucidate fipronil transformation pathways within the treatment system, data from the three sample types were compared; findings were generally consistent with transformation pathways reported previously (e.g., some fiproles were rarely detected in influent or biosolids, but frequently detected in effluent, indicating their formation during the treatment process). No correlations were found between WWTP characteristics and pesticide concentrations in biosolids. The fraction of organic carbon ( f OC ) of each biosolids sample was measured, and a statistically significant negative correlation was observed between f OC and some fiproles, but not fipronil; possible explanations are discussed. Additional analysis for two major agricultural pesticides (bifenthrin and permethrin) indicated that estimated mass loads of these pesticides in biosolids applied to land as a soil amendment are minimal (approximately 2 to 3 orders of magnitude lower) compared to inputs from agricultural applications. This study provides insight on the magnitude of pesticides entering the environment via land-applied biosolids; existing regulations surrounding agricultural pesticide applications are expected to also be protective of the relatively low inputs from biosolids.

Science of the Total Environment↗

USGS2023

Multiresidue extraction of current-use pesticides from complex solid matrices using energized dispersive guided extraction with analysis by gas and liquid chromatography tandem mass spectroscopy

The development of sample processing techniques that recover a broad suite of pesticides from solid matrices, while mitigating coextracted matrix interferences, and reducing processing time is beneficial for high throughput analyses. The objective of this study was to evaluate the effectiveness of an automated extraction system for pesticide analyses in solid environmental samples. An Energized Dispersive Guided Extraction (EDGE) system was used to evaluate two different extraction solvents in optimizing the extraction of 210 pesticides and pesticide transformation products. A graphitized carbon cleanup step was implemented, and three elution solvents were evaluated separately for analyte recoveries. Recoveries between 70 and 130% were achieved for 167 compounds in a test soil using acetonitrile as an extraction solvent and carbon cleanup with acetonitrile and dichloromethane elutions. Nine field samples (soil, sediment, and biosolids) were extracted using the newly developed method and were compared with a previously validated pressurized liquid extraction (PLE) method using an Accelerated Solvent Extraction (ASE) system. Concentrations obtained from the two methods were comparable (linear R 2 > 0.999), suggesting similar performance between the EDGE and PLE extractions in complex matrices. The new method provided slightly better sensitivities in comparison to the PLE method, ranging from 0.09 to 2.56 ng g −1 . The method presented here significantly reduces extraction setup and runtimes while also minimizing the volume of carcinogenic solvents ( e.g. , dichloromethane) used in the laboratory and presents a sensitive multiresidue method for a wide range of pesticides in solid matrices.

Chemosphere↗

USGS2022

Measured efficacy, bioaccumulation, and leaching of a transfluthrin-based insecticidal paint: A case study with a nuisance, nonbiting aquatic insect

BACKGROUND Pest management professionals will require a diverse, adaptive abatement toolbox to combat advanced challenges from disease vector and nuisance insect populations. Designed for post-application longevity, insecticidal paints offer extended residual effects on targeted insect pest populations; a measured understanding of active ingredient bioavailability over time is valuable to fully assess treatment efficacy and potential environmental risks. This study was initiated because a nuisance net-spinning caddisfly, Smicridea fasciatella , is lowering the quality of life for riverfront residents at the type locality. RESULTS We tested the efficacy and potential mobility of a transfluthrin-based paint (a.i. 0.50%), comparing the impacts of UV exposure and substrate texture over time. Direct UV exposure decreased efficacy (β ± S.E. = 0.008 ± 0.001, P < 0.001) and a coarse texture maintained greater efficacy (β ± S.E. = −3.7 ± 1.3, P = 0.004) over time. Notably, the coarse texture + indirect UV treatment maintained 100% mortality after 240 days. UV exposure and substrate texture did not have a significant impact on leachate concentrations over time, and successive immersion tests indicated a two-phase emission pattern. Bioaccumulation increased with time on the cuticle of dead adult S. fasciatella ; after 24 h of direct exposure the concentration of transfluthrin was 25.3 ± 0.9 ng/caddisfly with a maximum concentration of 345 ng/caddisfly after 7 days. CONCLUSION Our predictions were validated with measured, time-dependent impacts on efficacy, leachability, and bioaccumulation. Because of the mobility of active ingredient in the environment, insecticidal paints merit low-impact protocols to improve public health outcomes and environmental safety. © 2022 Society of Chemical Industry.

Pest Management Science↗

USGS2018

Dissolved pesticide concentrations in the lower Sacramento River and its source waters, California, 2016

As part of a collaborative study designed to better understand water-quality conditions in the Sacramento River, surface-water samples were collected from the lower Sacramento River and five of its tributaries and then analyzed by the U.S. Geological Survey for a suite of 162 current-use pesticides and pesticide degradates. Samples were collected in May and October 2016 at 16 sites on the Sacramento River and its tributaries. Samples were analyzed for pesticide concentrations by using gas chromatography with mass spectrometry and liquid chromatography with tandem mass spectrometry laboratory methods. A total of 27 pesticides and pesticide degradates were detected in the water samples collected during the study (12 herbicides, 9 insecticides, 5 fungicides, and 1 synergist). Two herbicides were detected in the suspended sediments filtered from the water samples. Pesticides were detected in 100 percent of the water samples, and mixtures of two or more pesticides were detected at all sites and in all but four samples. The pesticides detected most frequently in the May and October sampling periods were the herbicides hexazinone (detected in 88 percent of the water samples), and diuron (84 percent), and the fungicide azoxystrobin (84 percent). Pesticide concentrations ranged from below the method detection limits to 576 nanograms per liter (clomazone). All pesticides were detected at concentration levels lower than the U.S. Environmental Protection Agency’s aquatic life benchmarks (U.S. Environmental Protection Agency, 2017). During the May sampling period, the fungicides boscalid and azoxystrobin (both 94 percent); the herbicides clomazone, diuron, and hexazinone (all 94 percent); thiobencarb (88 percent); and metolachlor (81 percent) were the most frequently detected compounds. During the October sampling period, the herbicides hexazinone (81 percent) and diuron (75 percent) and the herbicide degradates 3,4-dichloroaniline (75 percent) and N-3,4-dichlorophenyl-N-methyl-urea (50 percent), along with the fungicide azoxystrobin (75 percent) and the insecticide methoxyfenozide (63 percent), were the most frequently detected compounds.

California↗

USGS2018

An initial comparison of pesticides and amphibian pathogens between natural and created wetlands in the New Jersey Pinelands, 2014–16

A study conducted by the U.S. Geological Survey, in cooperation with the New Jersey Pinelands Commission and Montclair State University, was designed to compare pesticide concentrations and the presence and prevalence of amphibian pathogens between natural ponds and two types of created wetlands, excavated ponds and stormwater basins, throughout the New Jersey Pinelands. The study described herein is part of a larger study by the New Jersey Pinelands Commission designed to compare the functional equivalency of natural and created wetlands throughout the New Jersey Pinelands. Sites were selected on the basis of land-use classifications within a 500-meter radius around each wetland from a pool of natural ponds, excavated ponds, and stormwater basins determined by the New Jersey Pinelands Commission. Water, bed-sediment, anuran-food, and composite larval-anuran-tissue samples were collected from four reference (minimum land-use effects) and four degraded (maximum land-use effects) sites from each wetland type for a total of 24 ponds or basins throughout the New Jersey Pinelands during 2014–16. Prevalence of Ranavirus was determined on the basis of tail clips collected from 60 individual larval anurans in each wetland, and 10 animals from each wetland also were swabbed for the presence of Batrachochytrium dendrobatidis (Bd). Other constituents measured included turbidity, pH, specific conductance, dissolved oxygen, dissolved organic carbon, percent organic carbon in sediment, and composite larval-anuran lipid content. The amount of altered land (percent agricultural plus percent developed) ranged from 0 to 62.4 percent for the natural ponds, 0 to 63.6 percent for the excavated ponds, and 23.3 to 80.2 percent for the stormwater basins. The herbicides atrazine and metolachlor were observed in 60 and 89 percent of the water samples, respectively. The insecticide bifenthrin was the most frequently detected current-use pesticide (greater than 25 percent of the samples) in bed-sediment, anuran-food, and composite larval-anuran-tissue samples. The legacy insecticide p,p' -DDT and its primary degradates p,p' -DDD and p,p' -DDE were the most frequently detected compounds in bed-sediment and anuran-food samples (32–76 percent in sediment samples and 24–72 percent in anuran-food samples). Significantly, greater numbers of pesticides and higher total pesticide concentrations were observed in stormwater basins than in natural and excavated ponds. Reference wetlands had fewer pesticides and lower total pesticide concentrations compared to degraded wetlands, indicating a positive relation between percent altered land and pesticides throughout the New Jersey Pinelands. Ranavirus was observed in larvae from 4 wetlands, including 1 reference natural pond, 1 degraded natural pond, and 2 degraded stormwater basins, with prevalence ranging from 3 to 43 percent. Bd was detected in swabs from 18 animals and in 4 natural ponds (1 reference and 3 degraded), 3 excavated ponds (all reference), and 2 stormwater basins (1 reference and 1 degraded); however, detection probability was low. In the wetlands with Bd detections, between 10 and 30 percent (between 1 and 3) of the animal’s swabbed tested positive for Bd. Owing to the limited number of positive detections for both Bd and Ranavirus , no statistical comparisons between wetland types and land-use classifications were possible.

New Jersey↗

USGS2017

Leaching and sorption of neonicotinoid insecticides and fungicides from seed coatings

Seed coatings are a treatment used on a variety of crops to improve production and offer protection against pests and fungal outbreaks. The leaching of the active ingredients associated with the seed coatings and the sorption to soil was evaluated under laboratory conditions using commercially available corn and soybean seeds to study the fate and transport of these pesticides under controlled conditions. The active ingredients (AI) included one neonicotinoid insecticide (thiamethoxam) and five fungicides (azoxystrobin, fludioxonil, metalaxyl, sedaxane thiabendazole). An aqueous leaching experiment was conducted with treated corn and soybean seeds. Leaching potential was a function of solubility and seed type. The leaching of fludioxonil, was dependent on seed type with a shorter time to equilibrium on the corn compared to the soybean seeds. Sorption experiments with the treated seeds and a solution of the AIs were conducted using three different soil types. Sorption behavior was a function of soil organic matter as well as seed type. For most AIs, a negative relationship was observed between the aqueous concentration and the log K oc . Sorption to all soils tested was limited for the hydrophilic pesticides thiamethoxam and metalaxyl. However, partitioning for the more hydrophobic fungicides was dependent on both seed type and soil properties. The mobility of fludioxonil in the sorption experiment varied by seed type indicating that the adjuvants associated with the seed coating could potentially play a role in the environmental fate of fludioxonil. This is the first study to assess, under laboratory conditions, the fate of pesticides associated with seed coatings using commercially available treated seeds. This information can be used to understand how alterations in agricultural practices (e.g., increasing use of seed treatments) can impact the exposure (concentration and duration) and potential effects of these chemicals to aquatic and terrestrial organisms.

Journal of Environmental Science and Health - Part↗

USGS2014

Dissolved pesticide concentrations entering the Sacramento-San Joaquin Delta from the Sacramento and San Joaquin Rivers, California, 2012-13

Surface-water samples were collected from the Sacramento and San Joaquin Rivers where they enter the Sacramento–San Joaquin Delta, and analyzed by the U.S. Geological Survey for a suite of 99 current-use pesticides and pesticide degradates. Samples were collected twice per month from May 2012 through July 2013 and from May 2012 through April 2013 at the Sacramento River at Freeport, and the San Joaquin River near Vernalis, respectively. Samples were analyzed by two separate laboratory methods by using gas chromatography with mass spectrometry or liquid chromatography with tandem mass spectrometry. Method detection limits ranged from 0.9 to 10.5 nanograms per liter (ng/L). A total of 37 pesticides and degradates were detected in water samples collected during the study (18 herbicides, 11 fungicides, 7 insecticides, and 1 synergist). The most frequently detected pesticides overall were the herbicide hexazinone (detected in 100 percent of the samples); 3,4-dichloroaniline (97 percent), which is a degradate of the herbicides diuron and propanil; the fungicide azoxystrobin (83 percent); and the herbicides diuron (72 percent), simazine (66 percent), and metolachlor (64 percent). Insecticides were rarely detected during the study. Pesticide concentrations varied from below the method detection limits to 984 ng/L (hexazinone). Twenty seven pesticides and (or) degradates were detected in Sacramento River samples, and the average number of pesticides per sample was six. The most frequently detected compounds in these samples were hexazinone (detected in 100 percent of samples), 3,4-dichloroaniline (97 percent), azoxystrobin (88 percent), diuron (56 percent), and simazine (50 percent). Pesticides with the highest detected maximum concentrations in Sacramento River samples included the herbicide clomazone (670 ng/L), azoxystrobin (368 ng/L), 3,4-dichloroaniline (364 ng/L), hexazinone (130 ng/L), and propanil (110 ng/L), and all but hexazinone are primarily associated with rice agriculture. In addition to the twice monthly sampling, surface-water samples were collected from the Sacramento River on 5 consecutive days following a rainfall event in the Sacramento urban area. Samples collected following this event contained an average of 11 pesticides. The insecticides carbaryl, fipronil, and imidacloprid; the herbicide DCPA; and the fungicide imazalil were only detected in the Sacramento River during this storm-runoff event, and two detections of fipronil during this period exceeded the U.S. Environmental Protection Agency Aquatic Life Benchmark (11 ng/L) for chronic toxicity to invertebrates in freshwater. In San Joaquin River samples, 26 pesticides and (or) degradates were detected, and the average number detected per sample was 9. The most frequently detected compounds in these samples were hexazinone and metolachlor (detected in 100 percent of samples); diuron (96 percent); the fungicide boscalid (96 percent); the degradates 3,4-dicloroaniline (92 percent) and NN-(3,4-Dichlorophenyl)-N’-methylurea (DCPMU; 83 percent); simazine (83 percent); and azoxystrobin (75 percent). The pesticides with the highest detected maximum concentrations were hexazinone (984 ng/L), diuron (695 ng/L), simazine (524 ng/L), the herbicide prometryn (155 ng/L), metolachlor (127 ng/L), boscalid (112 ng/L), DCPMU (111 ng/L), and the herbicide pendimethalin (108 ng/L).

California↗

USGS2013

Dissolved pesticide concentrations in the Sacramento-San Joaquin Delta and Grizzly Bay, California, 2011-12

Surface-water samples were collected from sites within the Sacramento-San Joaquin Delta and Grizzly Bay, California, during the spring in 2011 and 2012, and they were analyzed by the U.S. Geological Survey for a suite of 99 current-use pesticides and pesticide degradates. Samples were collected and analyzed as part of a collaborative project studying the occurrence and characteristics of phytoplankton in the San Francisco Estuary. Samples were analyzed by two separate laboratory methods employing gas chromatography/mass spectrometry or liquid chromatography with tandem mass spectrometry. Method detection limits ranged from 0.9 to 10.5 nanograms per liter (ng/L). Eighteen pesticides were detected in samples collected during 2011, and the most frequently detected compounds were the herbicides clomazone, diuron, hexazinone and metolachlor, and the diuron degradates 3,4-dichloroaniline and N-(3,4-dichlorophenyl)-N’-methylurea (DCPMU). Concentrations for all compounds were less than 75 ng/L, except for the rice herbicide clomazone and the fungicide tetraconazole, which had maximum concentrations of 535 and 511 ng/L, respectively. In samples collected in 2012, a total of 16 pesticides were detected. The most frequently detected compounds were the fungicides azoxystrobin and boscalid and the herbicides diuron, hexazinone, metolachlor, and simazine. Maximum concentrations for all compounds detected in 2012 were less than 75 ng/L, except for the fungicide azoxystrobin and the herbicides hexazinone and simazine, which were detected at up to 188, 134, and 140 ng/L, respectively.

California↗