SEARCH · Geology Reports

Results for “Toxics”

Search indexed USGS publications on groundwater, aquifers, geologic maps, mineral resources and earthquakes. Explore source records by subject and place.

SourceResearch connectionFrom yearThrough year

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 1,027 records · Page 57Linked to original sources

USGS1996

Comparison of the effects of seleno-Lmethionine, seleno-DL-methionine, and selenized yeast on reproduction of mallards

The toxicities of seleno- l -methionine, seleno- dl -methionine, and selenized yeast were compared. Ten pairs of mallards were fed a control diet and 15 pairs were fed diets containing 10 ppm selenium as seleno- dl -methionine, seleno- l -methionine, or selenized yeast. Hatching of fertile eggs was significantly lower for females fed 10 ppm selenium as seleno- dl -methionine (7.6%) and seleno- l -methionine (6.4%) than for controls (41.3%). Survival of ducklings was lower when their parents had been fed 10 ppm selenium as seleno- l -methionine (20.0%) than for controls (98.4%). The number of 6-day-old ducklings produced per female was significantly lower for mallards fed 10 ppm selenium as seleno- dl -methionine (0.47) or selenized yeast (2.67) than for controls (6.10), and was significantly lower for mallards fed seleno- l -methionine (0.13) than for mallards fed selenized yeast. The eighth eggs of females fed the dl or l forms of selenomethionine contained means of 9.2 and 8.9 ppm selenium, wet weight; these means were higher than the mean (6.6 ppm) for females fed selenized yeast. Among embryos that died at 7 days of age or older, the percentage of embryos that were deformed was 1.3% for controls, 24.6% for seleno- dl -methionine, 28.2% for seleno- l -methionine, and 11.0% for selenized yeast. The results suggested that seleno- dl -methionine and seleno- l -methionine were of similar toxicity and were both more toxic than selenium from selenized yeast.

Arkansas↗

USGS2015

Biodynamics of copper oxide nanoparticles and copper ions in an oligochaete: Part I: relative importance of water and sediment as exposure routes

Copper oxide (CuO) nanoparticles (NPs) are widely used, and likely released into the aquatic environment. Both aqueous (i.e., dissolved Cu) and particulate Cu can be taken up by organisms. However, how exposure routes influence the bioavailability and subsequent toxicity of Cu remains largely unknown. Here, we assess the importance of exposure routes (water and sediment) and Cu forms (aqueous and nanoparticulate) on Cu bioavailability and toxicity to the freshwater oligochaete, Lumbriculus variegatus , a head-down deposit-feeder. We characterize the bioaccumulation dynamics of Cu in L. variegatus across a range of exposure concentrations, covering both realistic and worst-case levels of Cu contamination in the environment. Both aqueous Cu (Cu-Aq; administered as Cu(NO 3 ) 2 ) and nanoparticulate Cu (CuO NPs), whether dispersed in artificial moderately hard freshwater or mixed into sediment, were weakly accumulated by L. variegatus . Once incorporated into tissues, Cu elimination was negligible, i.e., elimination rate constants were in general not different from zero for either exposure route or either Cu form. Toxicity was only observed after waterborne exposure to Cu-Aq at very high concentration (305 µgL -1 ), where all worms died. There was no relationship between exposure route, Cu form or Cu exposure concentration on either worm survival or growth. Slow feeding rates and low Cu assimilation efficiency (approximately 30%) characterized the uptake of Cu from the sediment for both Cu forms. In nature, L. variegatus is potentially exposed to Cu via both water and sediment. However, sediment progressively becomes the predominant exposure route for Cu in L. variegatus as Cu partitioning to sediment increases.

Aquatic Toxicology↗

USGS2019

Control of invasive sea lampreys using the piscicides TFM and niclosamide: Toxicology, successes & future prospects

The invasion of the Laurentian Great Lakes of North America by sea lampreys ( Petromyzon marinus ) in the early 20th century contributed to the depletion of commercial, recreational and culturally important fish populations, devastating the economies of communities that relied on the fishery. Sea lamprey populations were subsequently controlled using an aggressive integrated pest-management program which employed barriers and traps to prevent sea lamprey from migrating to their spawning grounds and the use of the piscicides (lampricides) 3-trifluoromethyl-4-nitrophenol (TFM) and niclosamide to eliminate larval sea lampreys from their nursery streams. Although sea lampreys have not been eradicated from the Great Lakes, populations have been suppressed to less than 10% of their peak numbers in the mid-1900s. The ongoing use of lampricides provides the foundation for sea lamprey control in the Great Lakes, one of the most successful invasive species control programs in the world. Yet, significant gaps remain in our understanding of how lampricides are taken-up and handled by sea lampreys, how lampricides exert their toxic effects, and how they adversely affect non-target invertebrate and vertebrates species. In this review we examine what has been learned about the uptake, handling and elimination, and the mode of TFM and niclosamide toxicity in lampreys and in non-target animals, particularly in the last 10 years. It is now clear that the mode of TFM toxicity is the same in non-target fishes and lampreys, in which TFM interferes with oxidative phosphorylation by the mitochondria leading to decreased ATP production. Vulnerability to TFM is related to abiotic factors such as water pH and alkalinity, which we propose changes the relative amounts of the bioavailable un-ionized form of TFM in the gill microenvironment. Niclosamide, which is also a molluscicide used to control snails in areas prone to schistosomiasis infections of humans, also likely works by uncoupling oxidative phosphorylation, but less is known about other aspects of its toxicology. The effects of TFM include reductions in energy stores, particularly glycogen and high energy phosphagens. However, non-target fishes readily recover from sub-lethal TFM exposure as demonstrated by the rapid restoration of energy stores and clearance of TFM. Although both TFM and niclosamide are non-persistent in the environment and critical for sea lamprey control, increasing public and institutional concerns about pesticides in the environment makes it imperative to explore other means of sea lamprey control. Accordingly, we also address possible “next-generation” strategies of sea lamprey control including genetic tools such as RNA interference and CRISPR-Cas9 to impair critical physiological processes (e.g. reproduction, digestion, metamorphosis) in lamprey, and the use of green chemistry to develop more environmentally benign chemical methods of sea lamprey control.

Great Lakes↗

USGS2025

Establishment of a cell culture from Daphnia magna as an in vitro model for (eco)toxicology assays: Case study using Bisphenol A as a representative cytotoxic and endocrine disrupting chemical

Bisphenol A (BPA) is a widely used industrial compound found in polycarbonate plastics, epoxy resin, and various polymer materials, leading to its ubiquitous presence in the environment. The toxicity of BPA to aquatic organisms has been well documented following in vivo exposure scenarios, with known cytotoxic and endocrine-disrupting effects. As such, BPA was used in this study as a well-characterized chemical to implement more ethical and resource-efficient scientific practices in toxicity testing through new approach methods (NAMs). Due to the frequent use of Daphnia spp. as a model organism in toxicology, we developed an in vitro cell culture system from Daphnia magna embryos, with optimized medium to support cell longevity. The cultures were maintained for up to two months, demonstrating their stability and suitability for cytotoxicity studies. Using this novel system, lethal concentration 50 (LC 50 ) values were determined at the 24 and 48 h time points following BPA exposure. Subsequently, oxidative stress, endocrine disruption, and DNA damage were assessed through gene expression, activity assays, and a comet assay in BPA-exposed cells. LC 50 values of 52 µM and 20 µM BPA were calculated after 24 and 48 h exposures, respectively. BPA cells exposed to 20 and 52 µM had significantly increased GSH, GPx, and GST activity levels. mRNA expression analysis revealed significant upregulations in the expression of hsp70, hsp90, gst, gpx, vtg1 , and cyp4 , with downregulations of sod, cat , and ecr following BPA exposure. Furthermore, comet assays showed a significantly higher level of DNA damage induced by BPA compared to controls, with greater comet and tail lengths. This study established a novel in vitro Daphnia model, using BPA as a case study for determining toxic effects, further highlighting the importance and applicability of utilizing alternative methods in ecotoxicological research through reducing animal use.

Aquatic Toxicology↗

USGS2021

Lethal impacts of selenium counterbalance the potential reduction in mercury bioaccumulation for freshwater organisms☆

Mercury (Hg), a potent neurotoxic element, can biomagnify through food webs once converted into methylmercury (MeHg). Some studies have found that selenium (Se) exposure may reduce MeHg bioaccumulation and toxicity, though this pattern is not universal. Se itself can also be toxic at elevated levels. We experimentally manipulated the relative concentrations of dietary MeHg and Se (as selenomethionine [SeMet]) for an aquatic grazer (the mayfly, Neocloeon triangulifer) and its food source (diatoms). Under low MeHg treatment (0.2 ng/L), diatoms exhibited a quadratic pattern, with decreasing diatom MeHg concentration up to 2.0 μg Se/L and increasing MeHg accumulation at higher SeMet concentrations. Under high MeHg treatment (2 ng/L), SeMet concentrations had no effect on diatom MeHg concentrations. Mayfly MeHg concentrations and biomagnification factors (concentration of MeHg in mayflies: concentration of MeHg in diatoms) declined with SeMet addition only in the high MeHg treatment. Mayfly MeHg biomagnification factors decreased from 5.3 to 3.3 in the high MeHg treatment, while the biomagnification factor was constant with an average of 4.9 in the low MeHg treatment. The benefit of reduced MeHg biomagnification was offset by non-lethal effects and high mortality associated with ‘protective’ levels of SeMet exposure. Mayfly larvae escape behavior (i.e., startle response) was greatly reduced at early exposure days. Larvae took nearly twice as long to metamorphose to adults at high Se concentrations. The minimum number of days to mayfly emergence did not differ by SeMet exposure, with an average of 13 days. We measured an LC50SeMet for mayflies of 3.9 μg Se/L, with complete mortality at concentrations ≥6.0 μg Se/L. High reproductive mortality occurred at elevated SeMet exposures, with only 0–18% emergence at ≥4.12 μg Se/L. Collectively, our results suggest that while there is some evidence that Se can reduce MeHg accumulation at the base of the food web at specific exposure levels of SeMet and MeHg, Se is also toxic to mayflies and could lead to negative effects that extend across ecosystem boundaries.

Environmental Pollution↗

USGS2006

Abundance and distribution of selected elements in soils, stream sediments, and selected forage plants from desert tortoise habitats in the Mojave and Colorado deserts, USA

A baseline and background chemical survey was conducted in southeastern California, USA, to identify potential sources of toxicants in natural and anthropogenically-altered habitats of the threatened desert tortoise (Gopherus agassizii). Soil, stream sediment, and plant samples were collected from six tortoise habitat study areas in the Mojave and Colorado deserts and analysed for up to 66 different elements. The chemical analyses provided new information on the abundances and distributions of selected elements in this region. Soil, stream-sediment, and plant analyses showed distinct variations in bulk chemistries from locality to locality. Variations were, in general, consistent with the many types of exposed rock units in the region, their highly variable bulk mineralogies, and chemical contents. Of elements in soils that might have been toxic to tortoises, only As seemed to be anomalous region-wide. Some soil and plant anomalies were clearly anthropogenic. In the Rand and Atolia mining districts, soil anomalies for As, Au, Cd, Hg, Sb, and(or) W and plant anomalies for As, Sb, and(or) W extend as far as ???15 km outward from the present area of mining; soils containing anomalous Hg were found at least 6 km away from old piles of tailings. The anomalous concentrations of As and Hg may have been the source of elevated levels of these elements found in ill tortoises from the region. In the Goldstone mining district, soil anomalies extended several km from the mining area. These areas probably represented anthropogenic surface contamination of dust redistributed by wind, vehicles, and rainfall. One of two study areas transected by a paved road (Chemehuevi Valley) showed weakly elevated levels of Pb, which extended as far as ???22 m from the pavement edge and were probably related to vehicle exhaust. No soil or plant samples from historically used military areas (Goldstone, Goffs, Chemehuevi Valley, Chuckwalla Bench) contained anomalous concentrations of the elements As, Cu, Cr, Fe, Pb, or Zn that could be ascribed to military maneuvers, vehicles, or ordnance. For future studies, the distribution and abundance of elements in the tortoise forage plants need to be evaluated for the respective roles of dust and systemic uptake. Additional chemical data from tortoise necropsies and nutritional studies are needed to determine the effects of potentially toxic elements in tortoise habitats on their health. ?? 2006 Elsevier Ltd. All rights reserved.

Journal of Arid Environments↗

USGS2004

Trace elements in moose (Alces alces) found dead in Northwestern Minnesota, USA

The moose ( Alces alces ) population in bog and forest areas of Northwestern Minnesota has declined for more than 25 years, and more recently the decline is throughout Northwestern Minnesota. Both deficiencies and elevations in trace elements have been linked to the health of moose worldwide. The objective of this study was to evaluate whether trace element toxicity or deficiency may have contributed to the decline of moose in Northwestern Minnesota. Livers of 81 moose found dead in Northwestern Minnesota in 1998 and 1999 were analyzed for trace elements. With the exception of selenium (Se) and copper (Cu), trace elements were not at toxic or deficient levels based on criteria set for cattle. Selenium concentrations in moose livers based on criteria set for cattle were deficient in 3.7% of livers and at a chronic toxicity level in 16% of livers. Copper concentrations based on criteria set for cattle were deficient in 39.5% of livers, marginally deficient in 29.5% of livers and adequate in 31% of livers. Moose from agricultural areas had higher concentrations, on average, of Cd, Cu, Mo and Se in their livers than moose from bog and forest areas. Older moose had higher concentrations of Cd and Zn, and lower concentrations of Cu than younger moose. Copper deficiency, which has been associated with population declines of moose in Alaska and Sweden, may be a factor contributing to the decline of moose in Northwestern Minnesota. (C) 2004 Elsevier B.V. All rights reserved.

Minnesota↗

USGS2006

Environmental contaminants and biomarker responses in fish from the Columbia River and its tributaries: spatial and temporal trends

Fish were collected from 16 sites on rivers in the Columbia River Basin (CRB) from September 1997 to April 1998 to document temporal and spatial trends in the concentrations of accumulative contaminants and to assess contaminant effects on the fish. Sites were located on the mainstem of the Columbia River and on the Snake, Willamette, Yakima, Salmon, and Flathead Rivers. Common carp (Cyprinus carpio), black bass (Micropterus sp.), and largescale sucker (Catostomus macrocheilus) were the targeted species. Fish were field-examined for external and internal lesions, selected organs were weighed to compute somatic indices, and tissue and fluid samples were preserved for fish health and reproductive biomarker analyses. Composite samples of whole fish, grouped by species and gender, from each site were analyzed for organochlorine and elemental contaminants using instrumental methods and for 2,3,7,8-tetrachloro dibenzo-p-dioxin-like activity (TCDD-EQ) using the H4IIE rat hepatoma cell bioassay. Overall, pesticide concentrations were greatest in fish from lower CRB sites and elemental concentrations were greatest in fish from upper CRB sites. These patterns reflected land uses. Lead (Pb) concentrations in fish from the Columbia River at Northport and Grand Coulee, Washington (WA) exceeded fish and wildlife toxicity thresholds (> 0.4 ??g/g). Selenium (Se) concentrations in fish from the Salmon River at Riggins, Idaho (ID), the Columbia River at Vernita Bridge, WA, and the Yakima River at Granger, WA exceeded toxicity thresholds for piscivorous wildlife (> 0.6 ??g/g). Mercury (Hg) concentrations in fish were elevated throughout the basin but were greatest (> 0.4 ??g/g) in predatory fish from the Salmon River at Riggins, ID, the Yakima River at Granger, WA, and the Columbia River at Warrendale, Oregon (OR). Residues of p,p???-DDE were greatest (> 0.8 ??g/g) in fish from agricultural areas of the Snake, Yakima, and Columbia River basins but were not detected in upper CRB fish. Other organochlorine pesticides did not exceed toxicity thresholds in fish or were detected infrequently. Total polychlorinated biphenyls (PCBs; > 0.11 ??g/g) and TCDD-EQs (> 5 pg/g) exceeded wildlife guidelines in fish from the middle and lower CRB, and ethoxyresorufin O-deethylase (EROD) activity was also elevated at many of the same sites. Temporal trend analysis indicated decreasing or stable concentrations of Pb, Se, Hg, p,p???-DDE, and PCBs at most sites where historical data were available. Altered biomarkers were noted in fish throughout the CRB. Fish from some stations had responded to chronic contaminant exposure as indicated by fish health and reproductive biomarker results. Although most fish from some sites had grossly visible external or internal lesions, histopathological analysis determined these to be inflammatory responses associated with helminth or myxosporidian parasites. Many largescale sucker from the Columbia River at Northport and Grand Coulee, WA had external lesions and enlarged spleens, which were likely associated with infections. Intersex male smallmouth bass (Micropterus dolomieu) were found in the Snake River at Lewiston, ID and the Columbia River at Warrendale, OR. Male bass, carp, and largescale sucker containing low concentrations of vitellogenin were common in the CRB, and comparatively high concentrations (> 0.3 mg/mL) were measured in male fish from the Flathead River at Creston, Montana, the Snake River at Ice Harbor Dam, WA, and the Columbia River at Vernita Bridge, WA and Warrendale, OR. Results from our study and other investigations indicate that continued monitoring in the CRB is warranted to identify consistently degraded sites and those with emerging problems. ?? 2005 Elsevier B.V. All rights reserved.

Columbia River Basin↗

USGS2008

Chemical contaminants, health indicators, and reproductive biomarker responses in fish from rivers in the Southeastern United States

Largemouth bass ( Micropterus salmoides ) and common carp ( Cyprinus carpio ) were collected from 13 sites located in the Mobile (MRB), Apalachicola–Flint–Chattahoochee (ARB), Savannah (SRB), and Pee Dee (PRB) River Basins to document spatial trends in accumulative chemical contaminants, health indicators, and reproductive biomarkers. Organochlorine residues, 2,3,7,8-tetrachlorodibenzo- p -dioxin-like activity (TCDD-EQ), and elemental contaminants were measured in composite samples of whole fish, grouped by species and gender, from each site. Mercury (Hg) and polychlorinated biphenyls (PCBs) were the primary contaminants of concern. Concentrations of Hg in bass samples from all basins exceeded toxicity thresholds for piscivorous mammals (> 0.1 μg/g ww), juvenile and adult fish (> 0.2 μg/g ww), and piscivorous birds (> 0.3 μg/g ww). Total PCB concentrations in samples from the MRB, ARB, and PRB were > 480 ng/g ww and may be a risk to piscivorous wildlife. Selenium concentrations also exceeded toxicity thresholds (> 0.75 μg/g ww) in MRB and ARB fish. Concentrations of other formerly used (total chlordanes, dieldrin, endrin, aldrin, mirex, and hexachlorobenzene) and currently used (pentachlorobenzene, pentachloroanisole, dacthal, endosulfan, γ-hexachlorocyclohexane, and methoxychlor) organochlorine residues were generally low or did not exceed toxicity thresholds for fish and piscivorous wildlife. TCDD-EQs exceeded wildlife dietary guidelines (> 5 pg/g ww) in MRB and PRB fish. Hepatic ethoxyresorufin O -deethylase (EROD) activity was generally greatest in MRB bass and carp. Altered fish health indicators and reproductive biomarker were noted in individual fish, but mean responses were similar among basins. The field necropsy and histopathological examination determined that MRB fish were generally in poorer health than those from the other basins, primarily due to parasitic infestations. Tumors were found in few fish ( n = 5; 0.01%); ovarian tumors of smooth muscle origin were found in two ARB carp from the same site. Intersex gonads were identified in 47 male bass (42%) representing 12 sites and may indicate exposure to potential endocrine disrupting compounds. Comparatively high vitellogenin concentrations (> 0.35 mg/mL) in male fish from the MRB, SRB, and PRB indicate exposure to estrogenic or anti-androgenic chemicals.

Science of the Total Environment↗

USGS2012

MiniSipper: A new in situ water sampler for high-resolution, long-duration acid mine drainage monitoring

Abandoned hard-rock mines can be a significant source of acid mine drainage (AMD) and toxic metal pollution to watersheds. In Colorado, USA, abandoned mines are often located in remote, high elevation areas that are snowbound for 7–8 months of the year. The difficulty in accessing these remote sites, especially during winter, creates challenging water sampling problems and major hydrologic and toxic metal loading events are often under sampled. Currently available automated water samplers are not well suited for sampling remote snowbound areas so the U.S. Geological Survey (USGS) has developed a new water sampler, the MiniSipper, to provide long-duration, high-resolution water sampling in remote areas. The MiniSipper is a small, portable sampler that uses gas bubbles to separate up to 250 five milliliter acidified samples in a long tubing coil. The MiniSipper operates for over 8 months unattended in water under snow/ice, reduces field work costs, and greatly increases sampling resolution, especially during inaccessible times. MiniSippers were deployed in support of an U.S. Environmental Protection Agency (EPA) project evaluating acid mine drainage inputs from the Pennsylvania Mine to the Snake River watershed in Summit County, CO, USA. MiniSipper metal results agree within 10% of EPA-USGS hand collected grab sample results. Our high-resolution results reveal very strong correlations (R 2 > 0.9) between potentially toxic metals (Cd, Cu, and Zn) and specific conductivity at the Pennsylvania Mine site. The large number of samples collected by the MiniSipper over the entire water year provides a detailed look at the effects of major hydrologic events such as snowmelt runoff and rainstorms on metal loading from the Pennsylvania Mine. MiniSipper results will help guide EPA sampling strategy and remediation efforts in the Snake River watershed.

Colorado↗

USGS2016

Avian mercury exposure and toxicological risk across western North America: A synthesis

Methylmercury contamination of the environment is an important issue globally, and birds are useful bioindicators for mercury monitoring programs. The available data on mercury contamination of birds in western North America were synthesized. Original data from multiple databases were obtained and a literature review was conducted to obtain additional mercury concentrations. In total, 29219 original bird mercury concentrations from 225 species were compiled, and an additional 1712 mean mercury concentrations, representing 19998 individuals and 176 species, from 200 publications were obtained. To make mercury data comparable across bird tissues, published equations of tissue mercury correlations were used to convert all mercury concentrations into blood-equivalent mercury concentrations. Blood-equivalent mercury concentrations differed among species, foraging guilds, habitat types, locations, and ecoregions. Piscivores and carnivores exhibited the greatest mercury concentrations, whereas herbivores and granivores exhibited the lowest mercury concentrations. Bird mercury concentrations were greatest in ocean and salt marsh habitats and lowest in terrestrial habitats. Bird mercury concentrations were above toxicity benchmarks in many areas throughout western North America, and multiple hotspots were identified. Additionally, published toxicity benchmarks established in multiple tissues were summarized and translated into a common blood-equivalent mercury concentration. Overall, 66% of birds sampled in western North American exceeded a blood-equivalent mercury concentration of 0.2 μg/g wet weight (ww; above background levels), which is the lowest-observed effect level, 28% exceeded 1.0 μg/g ww (moderate risk), 8% exceeded 3.0 μg/g ww (high risk), and 4% exceeded 4.0 μg/g ww (severe risk). Mercury monitoring programs should sample bird tissues, such as adult blood and eggs, that are most-easily translated into tissues with well-developed toxicity benchmarks and that are directly relevant to bird reproduction. Results indicate that mercury contamination of birds is prevalent in many areas throughout western North America, and large-scale ecological attributes are important factors influencing bird mercury concentrations.

Science of the Total Environment↗

USGS2021

Predicting the spatiotemporal exposure of aquatic species to intrusions of fire retardant in streams with limited data

Because fire retardant can enter streams and harm aquatic species including endangered fish, agencies such as the U.S. Forest Service (USFS) must estimate the downstream extent of toxic effects every time fire retardant enters streams (denoted as an “intrusion”). A challenge in estimating the length of stream affected by the intrusion and the exposure time of species in the affected reach is the lack of data typically available on the stream's geometry and flow characteristics. Previously, the USFS estimated the affected reach length assuming instantaneous mixing of the retardant over the reach; however, this approach neglects key river mixing processes. An approach is described that accounts for advection and dispersion of the retardant as well as the downstream growth of the stream. Applied to 13 intrusions documented by the USFS, the new approach shows affected reach lengths range between 8.0 and 362 km; all 13 cases exceeded previous estimates from an instantaneous mixing model. The time that a stationary individual in the affected reach is exposed to concentrations above a pre-defined toxicity threshold (10% of 96-hour LC 50 , for example) ranges from 0.17 to 2.73 h, with all but one case having a maximum exposure time less than 1.5 h. Results from 1152 hypothetical intrusions provided by the USFS confirm that exposure times rarely exceed 5 h. This result suggests that 96-hour tests to determine toxicity (LC 50 ) to various species should be reconsidered. Although the approach described can be improved in several ways, it provides a first estimate of the effects of fire retardant intrusions.

Science of the Total Environment↗

USGS2022

New-generation pesticides are prevalent in California's Central Coast streams

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 sampled. About one-half (48%) of the 253 pesticides measured were detected at least once and 27 were detected in 10% or more of samples. 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 samples and 10 or more in 32% of samples. 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 sampling 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.

California↗

USGS2023

Ammonia and aquatic ecosystems – A review of global sources, biogeochemical cycling, and effects on fish

The purpose of this review is to better understand the full life cycle and influence of ammonia from an aquatic biology perspective. While ammonia has toxic properties in water and air, it also plays a central role in the biogeochemical nitrogen (N) cycle and regulates mechanisms of normal and abnormal fish physiology. Additionally, as the second most synthesized chemical on Earth, ammonia contributes economic value to many sectors, particularly fertilizers, energy storage, explosives, refrigerants, and plastics. But, with so many uses, industrial N 2 -fixation effectively doubles natural reactive N concentrations in the environment. The consequence is global, with excess fixed nitrogen driving degradation of soils, water, and air; intensifying eutrophication, biodiversity loss, and climate change; and creating health risks for humans, wildlife, and fisheries. Thus, the need for ammonia research in aquatic systems is growing. In response, we prepared this review to better understand the complexities and connectedness of environmental ammonia. Even the term “ammonia” has multiple meanings. So, we have clarified the nomenclature, identified units of measurement, and summarized methods to measure ammonia in water. We then discuss ammonia in the context of the N-cycle, review its role in fish physiology and mechanisms of toxicity, and integrate the effects of human N-fixation, which continuously expands ammonia's sources and uses. Ammonia is being developed as a carbon-free energy carrier with potential to increase reactive nitrogen in the environment. With this in mind, we review the global impacts of excess reactive nitrogen and consider the current monitoring and regulatory frameworks for ammonia. The presented synthesis illustrates the complex and interactive dynamics of ammonia as a plant nutrient, energy molecule, feedstock, waste product, contaminant, N-cycle participant, regulator of animal physiology, toxicant, and agent of environmental change. Few molecules are as influential as ammonia in the management and resilience of Earth's resources.

Science of the Total Environment↗

USGS2024

Multiple lines of evidence point to pesticides as stressors affecting invertebrate communities in small streams in five United States regions

Multistressor studies were performed in five regions of the United States to assess the role of pesticides as stressors affecting invertebrate communities in wadable streams. Pesticides and other chemical and physical stressors were measured in 75 to 99 streams per region for 4 weeks, after which invertebrate communities were surveyed (435 total sites). Pesticides were sampled weekly in filtered water, and once in bed sediment. The role of pesticides as a stressor to invertebrate communities was assessed by evaluating multiple lines of evidence: toxicity predictions based on measured pesticide concentrations, multivariate models and other statistical analyses, and previously published mesocosm experiments. Toxicity predictions using benchmarks and species sensitivity distributions and statistical correlations suggested that pesticides were present at high enough concentrations to adversely affect invertebrate communities at the regional scale. Two undirected techniques—boosted regression tree models and distance-based linear models—identified which pesticides were predictors of (respectively) invertebrate metrics and community composition. To put insecticides in context with known, influential covariates of invertebrate response, generalized additive models were used to identify which individual pesticide(s) were important predictors of invertebrate community condition in each region, after accounting for natural covariates. Four insecticides were identified as stressors to invertebrate communities at the regional scale: bifenthrin, chlordane, fipronil and its degradates, and imidacloprid. Fipronil was particularly important in the Southeast region, and imidacloprid, bifenthrin, and chlordane were important in multiple regions. For imidacloprid, bifenthrin, and fipronil, toxicity predictions were supported by mesocosm experiments that demonstrated adverse effects on naïve aquatic communities when dosed under controlled conditions. These multiple lines of evidence do not prove causality—which is challenging in the field under multistressor conditions—but they make a strong case for the role of insecticides as stressors adversely affecting invertebrate communities in streams within the five sampled regions.

Science of the Total Environment↗

USGS2024

Factors contributing to pesticide contamination in riverine systems: The role of wastewater and landscape sources

Wastewater treatment plant (WWTP) discharges can be a source of organic contaminants, including pesticides, to rivers. An integrated model was developed for the Potomac River watershed (PRW) to determine the amount of accumulated wastewater percentage of streamflow (ACCWW) and calculate predicted environmental concentrations (PECs) for 14 pesticides in non-tidal National Hydrography Dataset Plus Version 2.1 stream segments. Predicted environmental concentrations were compared to measured environmental concentrations (MECs) from 32 stream sites that represented a range of ACCWW and land use to evaluate model performance and to assess possible non-WWTP loading sources. Statistical agreement between PECs and MECs was strongest for insecticides, followed by fungicides and herbicides. Principal component analysis utilizing optical fluorescence and ancillary water quality data identified wastewater and urban runoff sources. Pesticides that indicated relatively larger sources from WWTPs included dinotefuran, fipronil, carbendazim, thiabendazole, and prometon whereas imidacloprid, azoxystrobin, propiconazole, tebuconazole, and diuron were more related to urban runoff. In addition, PECs generally comprised a low proportion of MECs, which indicates possible dominant loading sources beyond WWTP discharges. Cumulative potential toxicity was higher for sites with greater ACCWW and/or located in developed areas. Imidacloprid, fipronil, and carbendazim accounted for the largest portion of predicted potential toxicity across sites. The chronic aquatic life toxicity benchmarks for freshwater invertebrates were exceeded for 82 % of the imidacloprid detections ( n = 28) and 47 % of the fipronil detections ( n = 19). These results highlight the ecological implications of pesticide contamination from WWTP discharges and also the potential legacy effects from accumulated soil and groundwater sources. Pesticide management strategies that mitigate both current and historical impacts may improve the health of aquatic ecosystems.

Potomac River watershed↗

USGS2003

Photodegradation of roxarsone in poultry litter leachates

Arsenic compounds have been used extensively in agriculture in the US for applications ranging from cotton herbicides to animal feed supplements. Roxarsone (3-nitro-4-hydroxyphenylarsonic acid), in particular, is used widely in poultry production to control coccidial intestinal parasites. It is excreted unchanged in the manure and introduced into the environment when litter is applied to farmland as fertilizer. Although the toxicity of roxarsone is less than that of inorganic arsenic, roxarsone can degrade, biotically and abiotically, to produce more toxic inorganic forms of arsenic, such as arsenite and arsenate. Experiments were conducted on aqueous litter leachates to test the stability of roxarsone under different conditions. Laboratory experiments have shown that arsenite can be cleaved photolytically from the roxarsone moiety at pH 4-8 and that the degradation rate increases with increasing pH. Furthermore, the rate of photodegradation increases with nitrate and natural organic matter concentration, reactants that are commonly found in poultry-litter-water leachates. Additional photochemical reactions rapidly oxidize the cleaved arsenite to arsenate. The formation of arsenate is not entirely undesirable, because it is less mobile in soil systems and less toxic than arsenite. A possible mechanism for the degradation of roxarsone in poultry litter leachates is proposed. The results suggest that poultry litter storage and field application practices could affect the degradation of roxarsone and subsequent mobilization of inorganic arsenic species. ?? 2002 Elsevier Science B.V. All rights reserved.

Science of the Total Environment↗

USGS2001

Geochemical and mineralogical controls on trace element release from the Penn Mine base-metal slag dump, California

Base-metal slag deposits at the Penn Mine in Calaveras County, California, are a source of environmental contamination through leaching of potentially toxic elements. Historical Cu smelting at Penn Mine (1865-1919) generated approximately 200,000 m3 of slag. The slag deposits, which are flooded annually by a reservoir used for drinking water and irrigation, also may be in contact with acidic ground waters (pH < 4) from the adjacent mine area. Slags vary from grey to black, are glassy to crystalline, and range in size from coarse sand to large (0.6 ?? 0.7 ?? 1.5 m), tub-shaped casts. Metals are hosted by a variety of minerals and two glass phases. On the basis of mineralogy, slags are characterized by 4 main types: fayalite-rich, glassy, willemite-rich, and sulfide-rich. The ranges in metal and metalloid concentrations of 17 slag samples are: As, 0.0004-0.92; Ba, 0.13-2.9; Cd, 0.0014-1.4; Cu, 0.18-6.4; Pb, 0.02-11; and Zn, 3.2-28 wt.%. Leachates from Toxicity Characteristic Leaching Procedure tests (acetic acid buffered at pH 4.93) on two wiltemite-rich slags contained Cd and Pb concentrations (up to 2.5 and 30 mg/l, respectively) in excess of US Environmental Protection Agency (USEPA) regulatory limits. Analyses of filtered (0.45 ??m) water, collected within the flooded slag dump during reservoir drawdown, reveal concentrations of Cd (1.7 ??g/l), Cu (35 ??g/l), and Zn (250 ??g/l) that exceed USEPA chronic toxicity guidelines for the protection of aquatic life. Data from field and laboratory studies were used to develop geochemical models with the program EQ3/6 that simulate irreversible mass-transfer between slag deposits and reservoir waters. These models include kinetic rate laws for abiotic sulfide oxidation and surface-controlled dissolution of silicates, oxides, and glass. Calculations demonstrate that the main processes controlling dissolved metal concentrations are (1) dissolution of fayalite, willemite, and glass; (2) sulfide oxidation; and (3) secondary phase precipitation. Close agreement between model results and measured concentrations of Al, Ba, Cu, Fe, SiO2, and SO4 in the slag dump pore waters suggests that the dissolved concentrations of these elements are controlled by solubility equilibrium with secondary phases. Differences between predicted and measured Cd and Pb concentrations imply that field weathering rates of glass and sulfides are approximately two orders of magnitude lower than laboratory rates. Overprediction of Pb release may also reflect other attenuation processes in the natural system, such as sorption or coprecipitation. ?? 2001 Elsevier Science Ltd. All rights reserved.

Applied Geochemistry↗