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USGS2024

The Ecosystem Approach in the 21st century: Guiding science and management – A synthesis

Maintaining the integrity and health of aquatic ecosystems is critical to sustaining the many valued services that they provide society. Unfortunately, achieving this goal has proven challenging in most of the world's large ecosystems owing to rampant environmental change caused by human-driven stress, including accelerating climate change, pollution of waterways, habitat modification and destruction, and the continued spread of non-native species (He and Silliman, 2019; Jenny et al., 2020; Smith et al., 2015; Steffen et al., 2007). These stressors, which can also include purposeful management actions (e.g. nutrient and fisheries management), are presenting a grave challenge globally to efforts aimed at securing a sustainable future for nature, society, and the economy.

Aquatic Ecosystem Health & Management↗

USGS2010

Accumulation of current-use and organochlorine pesticides in crab embyros from northern California, USA

Invertebrates have long been used as resident sentinels for assessing ecosystem health and productivity. The shore crabs, Hemigrapsus oregonensis and Pachygrapsus crassipes, are abundant in estuaries and beaches throughout northern California, USA and have been used as indicators of habitat conditions in several salt marshes. The overall objectives of the present study were to conduct a lab-based study to test the accumulation of current-use pesticides, validate the analytical method and to analyze field-collected crabs for a suite of 74 current-use and legacy pesticides. A simple laboratory uptake study was designed to determine if embryos could bioconcentrate the herbicide molinate over a 7-d period. At the end of the experiment, embryos were removed from the crabs and analyzed by gas chromatography/mass spectrometry. Although relatively hydrophilic (log K(OW) of 2.9), molinate did accumulate with an estimated bioconcentration factor (log BCF) of approximately 2.5. Following method validation, embryos were collected from two different Northern California salt marshes and analyzed. In field-collected embryos 18 current-use and eight organochlorine pesticides were detected including synthetic pyrethroids and organophosphate insecticides, as well as DDT and its degradates. Lipid-normalized concentrations of the pesticides detected in the field-collected crab embryos ranged from 0.1 to 4 ppm. Pesticide concentrations and profiles in crab embryos were site specific and could be correlated to differences in land-use practices. These preliminary results indicate that embryos are an effective sink for organic contaminants in the environment and have the potential to be good indicators of ecosystem health, especially when contaminant body burden analyses are paired with reproductive impairment assays.

California↗

USGS2005

Retrospective ecotoxicological data and current information needs for terrestrial vertebrates residing in coastal habitat of the United States

The Contaminant Exposure and Effects—Terrestrial Vertebrates (CEE-TV) database was developed to conduct simple searches for ecotoxicological information, examine exposure trends, and identify significant data gaps. The CEE-TV database contains 16,696 data records on free-ranging amphibians, reptiles, birds, and mammals residing in estuarine and coastal habitats of the Atlantic, Gulf, and Pacific coasts, Alaska, Hawaii, and the Great Lakes. Information in the database was derived from over 1800 source documents, representing 483 unique species (about 252,000 individuals), with sample collection dates spanning from 1884 to 2003. The majority of the records contain exposure data (generally contaminant concentrations) on a limited number ( n = 209) of chlorinated and brominated compounds, cholinesterase-inhibiting pesticides, economic poisons, metals, and petroleum hydrocarbons, whereas only 9.3% of the records contain biomarker or bioindicator effects data. Temporal examination of exposure data provides evidence of declining concentrations of certain organochlorine pesticides in some avian species ( e.g. , ospreys, Pandion haliaetus ), and an apparent increase in the detection and possibly the incidence of avian die-offs related to cholinesterase-inhibiting pesticides. To identify spatial data gaps, 11,360 database records with specific sampling locations were combined with the boundaries of coastal watersheds, and National Wildlife Refuge and National Park units. Terrestrial vertebrate ecotoxicological data were lacking in 41.9% of 464 coastal watersheds in the continental United States. Recent (1990–2003) terrestrial vertebrate contaminant exposure or effects data were available for only about half of the National Wildlife Refuge and National Park units in the geographic area encompassed by the database. When these data gaps were overlaid on watersheds exhibiting serious water quality problems and/or high vulnerability to pollution, 72 coastal watersheds, and 76 National Wildlife Refuge and 59 National Park units in the continental United States were found to lack recent terrestrial vertebrate ecotoxicology data. Delineation of data gaps in watersheds of concern can help prioritize monitoring in areas with impaired water quality and emphasize the need for comprehensive monitoring to gain a more complete understanding of coastal ecosystem health.

Archives of Environmental Contamination and Toxico↗

USGS2018

The influence of spatiotemporally decoupled land use on honey bee colony health and pollination service delivery

Societal dependence on insects for pollination of agricultural crops has risen amidst concerns over pollinator declines. Habitat loss and lack of forage have been implicated in the decline of both managed and native pollinators. Land use changes in the Northern Great Plains of the US, a region supporting over 1 million honey bee colonies annually, have shifted away from historical grassland ecosystems bees rely on for forage toward landscapes dominated by corn, soybeans, and other row crops. We investigated how land use impacts honey bee colony population size during the growing season and subsequent colony population size for almond pollination in central California the following February. We provide estimates of how land use affects beekeeper economics by linking summer habitat with pollination service payments and later production of new colonies. Our results demonstrate that a greater presence of non-bee foraged agricultural crops surrounding apiaries in the summer results in smaller colonies by the end of the growing season. Apiaries with colonies exhibiting smaller population size in the autumn were also smaller during almond pollination the following spring; impacting the beekeeper with a reduced per colony rental fee for pollination services and reduced potential for creating new spring colonies, based on prior growing season land use. This study highlights the downstream effects of factors driving land use decisions on the ability of beekeepers to provide robust honey bee colonies to support the pollination industry on a national scale. It also demonstrates the direct linkages between habitat in the Northern Great Plains, bee health, and pollination services rendered elsewhere in the US.

Environmental Research Letters↗

USGS2006

Cladophora (Chlorophyta) spp. harbor human bacterial pathogens in nearshore water of Lake Michigan

Cladophora glomerata , a macrophytic green alga, is commonly found in the Great Lakes, and significant accumulations occur along shorelines during the summer months. Recently, Cladophora has been shown to harbor high densities of the fecal indicator bacteria Escherichia coli and enterococci. Cladophora may also harbor human pathogens; however, until now, no studies to address this question have been performed. In the present study, we determined whether attached Cladophora , obtained from the Lake Michigan and Burns Ditch (Little Calumet River, Indiana) sides of a breakwater during the summers of 2004 and 2005, harbored the bacterial pathogens Shiga toxin-producing Escherichia coli (STEC), Salmonella , Shigella , and Campylobacter . The presence of potential pathogens and numbers of organisms were determined by using cultural methods and by using conventional PCR, most-probable-number PCR (MPN-PCR), and quantitative PCR (QPCR) performed with genus- and toxin-specific primers and probes. While Shigella and STEC were detected in 100% and 25%, respectively, of the algal samples obtained near Burns Ditch in 2004, the same pathogens were not detected in samples collected in 2005. MPN-PCR and QPCR allowed enumeration of Salmonella in 40 to 80% of the ditch- and lakeside samples, respectively, and the densities were up to 1.6 × 10 3 cells per g Cladophora . Similarly, these PCR methods allowed enumeration of up to 5.4 × 10 2 Campylobacter cells/g Cladophora in 60 to 100% of lake- and ditchside samples. The Campylobacter densities were significantly higher (P < 0.05) in the lakeside Cladophora samples than in the ditchside Cladophora samples. DNA fingerprint analyses indicated that genotypically identical Salmonella isolates were associated with geographically and temporally distinct Cladophora samples. However, Campylobacter isolates were genetically diverse. Since animal hosts are thought to be the primary habitat for Campylobacter and Salmonella species, our results suggest that Cladophora is a likely secondary habitat for pathogenic bacteria in Lake Michigan and that the association of these bacteria with Cladophora warrants additional studies to assess the potential health impact on beach users.

Applied and Environmental Microbiology↗

USGS1989

Suppression of antibody-producing cells in rainbow trout spleen sections exposed to copper in vitro

Immunosuppression was demonstrated in sections of rainbow trout Oncorhynchus mykiss (formerly Salmo gairdneri ) spleens immunized in vitro and exposed in culture to different concentrations of copper chloride. The sections were immunized with dinitrophenyl-Ficoll and cultured in Eagle's minimum essential medium with 2% fetal calf serum; half of the medium was withdrawn and replaced every other day. The passive hemolytic plaque assay was used to determine the number of antibody-producing cells 10 d after injection. In the sections cultured with the high copper concentration (100 μg/mL), all cells died; at copper concentrations of 0.1–10 μg/mL, leukocytes remained viable, but fewer antibody-producing cells were present than in organ sections cultured in medium without copper. This in vitro method reduces the number of animals needed and the length of time required to determine toxicity and immunosuppression, and it provides information on the effects of certain environmental pollutants on fish.

Journal of Aquatic Animal Health↗

USGS2026

Factors affecting benthic macroinvertebrate health in the City of Roanoke, Virginia, 2020–2023

Major waterways in the City of Roanoke (City) have failed to meet Virginia’s aquatic life designated use since 1996. Segments of the upper Roanoke River lack healthy benthic macroinvertebrate communities which prompted a total maximum daily load (TMDL) study by the Virginia Department of Environmental Quality (VDEQ) to identify the most probable stressor(s) causing the impairment. Excess fine sediment was identified as the most probable stressor impairing benthic macroinvertebrates on portions of the Roanoke River in 2006, and a watershed implementation plan published in 2016 required communities within the impaired watershed to implement projects that would reduce the load of fine sediment entering the Roanoke River. Additional benthic macroinvertebrate sampling and stream habitat assessments along the Roanoke River and Tinker Creek (a tributary to the Roanoke River that flows through the City) revealed continued impaired conditions, and subsequent stressor identification analysis was completed in 2023. Samples collected downstream of the City on the Roanoke River and Tinker Creek generally showed more impaired conditions relative to samples collected at locations upstream of the City. Based on this evaluation, sediment and sediment-bound polychlorinated biphenyls (PCBs) were identified as probable stressors while specific conductance, total nitrogen, and sediment metals were possible stressors in Tinker Creek; however, only a sediment TMDL target was identified to address impaired benthic macroinvertebrate communities. In the Roanoke River upstream of the Niagara Dam, sediment and total phosphorus were identified as probable stressors, sediment polycyclic aromatic hydrocarbons and sediment PCB were considered possible stressors; however, the TMDL target was only for total phosphorus. The City partnered with the U.S. Geological Survey (USGS) in 2016 to continuously monitor water quality and streamflow conditions on a major tributary of Tinker Creek, Lick Run, and by 2020, four similar monitoring stations were installed on the Roanoke River and Tinker Creek near the locations of benthic macroinvertebrate sampling. Monitored parameters included streamflow and/or gage height (water level), water temperature, pH, dissolved oxygen, specific conductance, and turbidity. Turbidity is a measure of the relative clarity of the water and was previously used to model suspended-sediment concentrations at the monitoring stations. The City also contracted Kirk Environmental, LLP (KE) to collect benthic macroinvertebrate samples and stream habitat assessments near the locations of the water-quality monitoring stations. Identified benthic macroinvertebrates were used to calculate the Virginia Stream Condition Index (SCI), a multi-metric index composed of eight biological attributes that represent elements of the structure and function of the benthic macroinvertebrate community that measure diversity, composition, and tolerance to pollution. Study objective: In this report, benthic macroinvertebrate samples and stream habitat assessment scores collected at four locations on the Roanoke River and Tinker Creek by KE and the VDEQ between 2020 and 2023 were compared to measured water-quality and streamflow conditions prior to sampling to evaluate patterns between benthic macroinvertebrate health, water quality, and hydrology.

Virginia↗

USGS2004

Concentrations of selected organochlorine compounds in fish tissue in the Mississippi Embayment Study Unit : Arkansas, Kentucky, Louisiana, Mississippi, Missouri, and Tennessee, 1995-99

Whole fish were collected at 52 sites during 1995-99 to evaluate the occurrence and distribution of selected organochlorine compounds in the Mississippi Embayment Study Unit. Samples were collected as part of the U.S. Geological Survey National Water Quality Assessment Program. From 5 to 8 fish were collected at each site; the fish were composited, and an aliquot of the tissue was analyzed for 28 organo-chlorine compounds, which included pesticides, pesticide degradates, and polychlorinated biphenyls. The use of these organochlorine compounds has been discontinued or severely restricted within the United States, but the continued detection of these compounds or their degradates in the air, water, soil, and biota in national surveys, coupled with known environmental problems associated with these compounds (such as a long half-life and the propensity to accumulate in living tissue), is cause for continued interest in their environmental fate. At least one organochlorine compound was detected in every fish-tissue sample, and as many as 15 different compounds were detected in some. The most frequently detected com-pounds were the degradates of p,p'-dichlorodiphenyltrichlo-roethane (p,p'-DDT); p,p'-dichlorodiphenyldichloroethylene (p,p'-DDE) was detected in every sample above the method reporting limit, and p,p'-dichlorodiphenyldichloroethane (p,p'-DDD), was detected in 94 percent of the samples. Polychlorinated biphenyl compounds and dieldrin were detected in 83 and 78 percent of fish-tissue samples, respectively. Because these were whole fish samples, the results are not directly comparable to human health standards, which are based on fish fillets. Comparison of these results, however, to the guidelines for the protection of fish-eating wildlife indicates that concentrations of the p,p'-DDT degradates and toxaphene continue to be of environmental concern.

Scientific Investigations Report↗

USGS1991

The Detroit River: Effects of contaminants and human activities on aquatic plants and animals and their habitats

Despite the extensive urbanization of its watershed, the Detroit River still supports diverse fish and wildlife populations. Conflicting uses of the river for waste disposal, water withdrawals, shipping, recreation, and fishing require innovative management. Chemicals added by man to the Detroit River have adversely affected the health and habitats of the river's plants and animals. In 1985, as part of an Upper Great Lakes Connecting Channels Study sponsored by Environment Canada and the U.S. Environmental Protection Agency, researchers exposed healthy bacteria, plankton, benthic macroinvertebrates, fish, and birds to Detroit River sediments and sediment porewater. Negative impacts included genetic mutations in bacteria; death of macroinvertebrates; accumulation of contaminants in insects, clams, fish, and ducks; and tumor formation in fish. Field surveys showed areas of the river bottom that were otherwise suitable for habitation by a variety of plants and animals were contaminated with chlorinated hydrocarbons and heavy metals and occupied only by pollution-tolerant worms. Destruction of shoreline wetlands and disposal of sewage and toxic substances in the Detroit River have reduced habitat and conflict with basic biological processes, including the sustained production of fish and wildlife. Current regulations do not adequately control pollution loadings. However, remedial actions are being formulated by the U.S. and Canada to restore degraded benthic habitats and eliminate discharges of toxic contaminants into the Detroit River.

Hydrobiologia↗

USGS2005

Identifying calcium sources at an acid deposition-impacted spruce forest: A strontium isotope, alkaline earth element multi-tracer approach

Depletion of calcium from forest soils has important implications for forest productivity and health. Ca is available to fine feeder roots from a number of soil organic and mineral sources, but identifying the primary source or changes of sources in response to environmental change is problematic. We used strontium isotope and alkaline earth element concentration ratios of trees and soils to discern the record of Ca sources for red spruce at a base-poor, acid deposition-impacted watershed. We measured 87 Sr/ 86 Sr and chemical compositions of cross-sectional stemwood cores of red spruce, other spruce tissues and sequential extracts of co-located soil samples. 87 Sr/ 86 Sr and Sr/Ba ratios together provide a tracer of alkaline earth element sources that distinguishes the plant-available fraction of the shallow organic soils from those of deeper organic and mineral soils. Ca/Sr ratios proved less diagnostic, due to within-tree processes that fractionate these elements from each other. Over the growth period from 1870 to 1960, 87 Sr/ 86 Sr and Sr/Ba ratios of stemwood samples became progressively more variable and on average trended toward values that considered together are characteristic of the uppermost forest floor. In detail the stemwood chemistry revealed an episode of simultaneous enhanced uptake of all alkaline earth elements during the growth period from 1930 to 1960, coincident with reported local and regional increases in atmospheric inputs of inorganic acidity. We attribute the temporal trends in stemwood chemistry to progressive shallowing of the effective depth of alkaline earth element uptake by fine roots over this growth period, due to preferential concentration of fine roots in the upper forest floor coupled with reduced nutrient uptake by roots in the lower organic and upper mineral soils in response to acid-induced aluminum toxicity. Although both increased atmospheric deposition and selective weathering of Ca-rich minerals such as apatite provide possible alternative explanations of aspects of the observed trends, the chemical buffering capacity of the forest floor-biomass pool limits their effectiveness as causal mechanisms.

Biogeochemistry↗

USGS2016

Regional assessment of persistent organic pollutants in resident mussels from New Jersey and New York estuaries following Hurricane Sandy

Resident mussels are effective indicators of ecosystem health and have been utilized in national assessment and monitoring studies for over two decades. Mussels were chosen because contaminant concentrations in their tissues respond to changes in ambient environmental levels, accumulation occurs with little metabolic transformation and a substantial amount of historic data were available. Mussels were collected from 10 previously studied locations approximately a year after Hurricane Sandy. Regionally, concentrations of polychlorinated biphenyls (PCBs) and polycyclic aromatic hydrocarbons (PAHs) decreased significantly, while concentrations of organochlorine pesticides (OCPs) remained unchanged, and polybrominated diphenyl ethers (PBDEs) increased compared to historic concentrations. Although concentrations of PCBs, OCPs and PAHs were at or near record low concentrations, long-term trends did not change after Hurricane Sandy. To effectively measure storm-induced impacts it is necessary to understand the factors influencing changes in mussel body burdens and have a long-term monitoring network and an ability to mobilize post event.

New Jersey, New York↗

USGS2021

Feral swine as sources of fecal contamination in recreational waters

Recreational waters are primary attractions at many national and state parks where feral swine populations are established, and thus are possible hotspots for visitor exposure to feral swine contaminants. Microbial source tracking (MST) was used to determine spatial and temporal patterns of fecal contamination in Congaree National Park (CONG) in South Carolina, U.S.A., which has an established population of feral swine and is a popular destination for water-based recreation. Water samples were collected between December 2017 and June 2019 from 18 surface water sites distributed throughout CONG. Host specific MST markers included human (HF183), swine (Pig2Bac), ruminant (Rum2Bac), cow (CowM3), chicken (CL), and a marker for shiga toxin producing Escherichia coli (STEC; stx2 ). Water samples were also screened for culturable Escherichia coli ( E. coli ) as part of a citizen science program. Neither the cow nor chicken MST markers were detected during the study. The human marker was predominantly detected at boundary sites or could be attributed to upstream sources. However, several detections within CONG without concurrent detections at upstream external sites suggested occasional internal contamination from humans. The swine marker was the most frequently detected of all MST markers, and was present at sites located both internal and external to the Park. Swine MST marker concentrations ≥ 43 gene copies/mL were associated with culturable E. coli concentrations greater than the U.S. Environmental Protection Agency beach action value for recreational waters. None of the MST markers showed a strong association with detection of the pathogenic marker ( stx2 ). Limited information about the health risk from exposure to fecal contamination from non-human sources hampers interpretation of the human health implications.

South Carolina↗

USGS2026

Cotton farming affects ileal virome in a sedentary wild passerine

Although a few studies have focused on avian gut virome variation in response to environmental stressors, none have assessed virome in relation to the production of chemically intensive crop-based agriculture that alters food resources and detrimentally affects various aspects of avian health and fitness. In this study, we used shotgun metatranscriptomics to assess whether exposure to cotton ( Gossypium spp.) production had a deleterious effect on the ileal virome of sedentary northern mockingbirds ( Mimus polyglottos ) sampled from two cotton-producing areas (16 birds in total) and one uncultivated area (7 birds) in Texas, USA. We recovered 43 viruses representing 13 virus families, which included two viruses that appear to be potential vertebrate pathogens. Individual sample richness varied from 25 to 33 viruses. Both virome richness (Adj. r 2 = 0.247, F (2, 20) = 4.615, P = 0.022) and composition (r 2 = 0.370, F (2, 20) = 5.883, P = 0.001) differed among three sampling regions. Cotton production was associated with the increase of virome richness (Adj. r 2 = 0.283, df = 22, P = 0.005). Pesticide occurrence data collected using silicone bands at the three sites suggest that virome compositional changes are not only associated with total pesticide exposure but are also particularly sensitive to the pesticide combinations detected at each location.

Texas↗

USGS2007

Questions and Answers About the Effects of Septic Systems on Water Quality in the La Pine Area, Oregon

Nitrate levels in the ground-water aquifer underlying the central Oregon city of La Pine and the surrounding area are increasing due to contamination from residential septic systems. This contamination has public health implications because ground water is the sole source of drinking water for area residents. The U.S. Geological Survey, in cooperation with Deschutes County and the Oregon Department of Environmental Quality, studied the movement and chemistry of nitrate in the aquifer and developed computer models that can be used to predict future nitrate levels and to evaluate alternatives for protecting water quality. This fact sheet summarizes the results of that study in the form of questions and answers.

Fact Sheet↗

USGS2017

Titanium

Titanium is a mineral commodity that is essential to the smooth functioning of modern industrial economies. Most of the titanium produced is refined into titanium dioxide, which has a high refractive index and is thus able to impart a durable white color to paint, paper, plastic, rubber, and wallboard. Because of their high strength-to-weight ratio and corrosion resistance, titanium metal and titanium metal alloys are used in the aerospace industry as well as for welding rod coatings, biological implants, and consumer goods. Ilmenite and rutile are currently the principal titanium-bearing ore minerals, although other minerals, including anatase, perovskite, and titanomagnetite, could have economic importance in the future. Ilmenite is currently being mined from two large magmatic deposits hosted in rocks of Proterozoic-age anorthosite plutonic suites. Most rutile and nearly one-half of the ilmenite produced are from heavy-mineral alluvial, fluvial, and eolian deposits. Titanium-bearing minerals occur in diverse geologic settings, but many of the known deposits are currently subeconomic for titanium because of complications related to the mineralogy or because of the presence of trace contaminants that can compromise the pigment production process. Global production of titanium minerals is currently dominated by Australia, Canada, Norway, and South Africa; additional amounts are produced in Brazil, India, Madagascar, Mozambique, Sierra Leone, and Sri Lanka. The United States accounts for about 4 percent of the total world production of titanium minerals and is heavily dependent on imports of titanium mineral concentrates to meet its domestic needs. Titanium occurs only in silicate or oxide minerals and never in sulfide minerals. Environmental considerations for titanium mining are related to waste rock disposal and the impact of trace constituents on water quality. Because titanium is generally inert in the environment, human health risks from titanium and titanium mining are minimal; however, the processes required to extract titanium from titanium feedstock can produce industrial waste.

Professional Paper↗

USGS2006

Sedimentation and Occurrence and Trends of Selected Chemical Constituents in Bottom Sediment, Empire Lake, Cherokee County, Kansas, 1905-2005

For about 100 years (1850-1950), the Tri-State Mining District in parts of southeast Kansas, southwest Missouri, and northeast Oklahoma was one of the primary sources of lead and zinc ore in the world. The mining activity in the Tri-State District has resulted in substantial historical and ongoing input of cadmium, lead, and zinc to the environment including Empire Lake in Cherokee County, southeast Kansas. The environmental contamination caused by the decades of mining activity resulted in southeast Cherokee County being listed on the U.S. Environmental Protection Agency's National Priority List as a superfund hazardous waste site in 1983. To provide some of the information needed to support efforts to restore the ecological health of Empire Lake, a 2-year study was begun by the U.S. Geological Survey in cooperation with the U.S. Fish and Wildlife Service and the Kansas Department of Health and Environment. A combination of sediment-thickness mapping and bottom-sediment coring was used to investigate sediment deposition and the occurrence of cadmium, lead, zinc, and other selected constituents in the bottom sediment of Empire Lake. The total estimated volume and mass of bottom sediment in Empire Lake were 44 million cubic feet and 2,400 million pounds, respectively. Most of the bottom sediment was located in the main body and the Shoal Creek arm of the reservoir. Minimal sedimentation was evident in the Spring River arm of the reservoir. The total mass of cadmium, lead, and zinc in the bottom sediment of Empire Lake was estimated to be 78,000 pounds, 650,000 pounds, and 12 million pounds, respectively. In the bottom sediment of Empire Lake, cadmium concentrations ranged from 7.3 to 76 mg/kg (milligrams per kilogram) with an overall median concentration of 29 mg/kg. Compared to an estimated background concentration of 0.4 mg/kg, the historical mining activity increased the median cadmium concentration by about 7,200 percent. Lead concentrations ranged from 100 to 950 mg/kg with an overall median concentration of 270 mg/kg. Compared to an estimated background concentration of 33 mg/kg, the median lead concentration was increased by about 720 percent as a result of mining activities. The range in zinc concentrations was 1,300 to 13,000 mg/kg with an overall median concentration of 4,900 mg/kg. Compared to an estimated background concentration of 92 mg/kg, the median zinc concentration was increased by about 5,200 percent. Within Empire Lake, the largest sediment concentrations of cadmium, lead, and zinc were measured in the main body of the reservoir. Within the Spring River arm of the reservoir, increased concentrations in the downstream direction likely were the result of tributary inflow from Short Creek, which drains an area that has been substantially affected by historical lead and zinc mining. Compared to nonenforceable sediment-quality guidelines, all Empire Lake sediment samples (representing 21 coring sites) had cadmium concentrations that exceeded the probable-effects guideline (4.98 mg/kg), which represents the concentration above which toxic biological effects usually or frequently occur. With one exception, cadmium concentrations exceeded the probable-effects guideline by about 180 to about 1,400 percent. With one exception, all sediment samples had lead concentrations that exceeded the probable-effects guideline (128 mg/kg) by about 10 to about 640 percent. All sediment samples had zinc concentrations that exceeded the probable-effects guideline (459 mg/kg) by about 180 to about 2,700 percent. Overall, cadmium, lead, and zinc concentrations in the bottom sediment of Empire Lake have decreased over time following the end of lead and zinc mining in the area. However, the concentrations in the most recently deposited bottom sediment (determined for 4 of 21 coring sites) still exceeded the probable-effects guideline by about 440 to 640 percent for cadmium, about 40 to 80 percent for lead, and about 580

Scientific Investigations Report↗

USGS2025

Analyzing multi-year nitrate concentration evolution in Alabama aquatic systems using a machine learning model

Rising nitrate contamination in water systems poses significant risks to public health and ecosystem stability, necessitating advanced modeling to understand nitrate dynamics more accurately. This study applies the long short-term memory (LSTM) modeling to investigate the hydrologic and environmental factors influencing nitrate concentration dynamics in rivers and aquifers across the state of Alabama in the southeast of the United States. By integrating dynamic data such as streamflow and groundwater levels with static catchment attributes, the machine learning model identifies primary drivers of nitrate fluctuations, offering detailed insights into the complex interactions affecting multi-year nitrate concentrations in natural aquatic systems. In addition, a novel LSTM-based approach utilizes synthetic surface water nitrate data to predict groundwater nitrate levels, helping to address monitoring gaps in aquifers connected to these rivers. This method reveals potential correlations between surface water and groundwater nitrate dynamics, which is particularly meaningful given the lack of water quality observations in many aquifers. Field applications further show that, while the LSTM model effectively captures seasonal trends, limitations in representing extreme nitrate events suggest areas for further refinement. These findings contribute to data-driven water quality management, enhancing understanding of nitrate behavior in interconnected water systems.

Alabama↗

USGS2022

Are you sleeping? Are you sleeping? Predicting invasion potential of sleeper species

Sleeper species are non-native species that are established in a region and could become invasive as climate change makes conditions more favorable for many non-native species. Before we can manage potential sleepers, we must first know their identity. We analyzed non-native, established plants in the Northeast United States (CT, MA, ME, NH, NY, RI, VT) using the Environmental Impact Classification for Alien Taxa (EICAT) protocol to identify species that have negative impacts on native ecological communities as well as negative impacts on agriculture, economies, or human health. Here, we highlight four potential sleeper species to watch out for. A full list of potential sleeper species and reported impacts can be found at https://doi.org/10.7275/yfss-tt69.

Connecticut, Maine, Massachusetts, New Hampshire, ↗