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At least 613 records · Page 34Linked to original sources
USGS1999

Quantity and quality of seepage from two earthen basins used to store livestock waste in southern Minnesota during the first year of operation, 1997-98

Numerous earthen basins have been constructed in Minnesota for storage of livestock waste. Typically, these basins are excavated pits with partially above-grade, earth-walled embankments and compacted clay liners. Some have drain tile installed around them to prevent shallow ground and soil water to discharge into the basins. Environmental concerns associated with the waste include contamination of ground water by nitrogen compounds and pathogens. The U.S. Geological Survey, in cooperation with the MFC A (Minnesota Pollution Control Agency), studied the quantity and quality of seepage from two earthen basins used to store livestock waste in southern Minnesota during the first year of operation. One basin (site A), located at a small dairy farm, holds a manuresilage mixture, milkhouse wastewater, and local runoff; the other basin (site B), located at a large hog farm, holds a manure-water mixture from a nearby gestation barn. Monitoring systems were installed below compacted clay liners in portions of the sidewalls and bottoms of the basins to determine the quantity and quality of the seepage. Total seepage flow from the site A basin ranged from about 900 to 2,400 gal/d (gallons per day) except during April 1998 when the flow increased to about 4,200 gal/d. Seepage flow in areal units, which closely correlated with flow in gal/d, generally ranged from about 0.07 to 0.18 in./d (inches per day), which exceeded the recommended maximum design rate of 0.018 in./d established by the MPCA. Seepage flow commonly was greater through the sidewalls than through the bottom. Seepage from the site A basin (based on 11 samples each from the bottom and sidewall) had chloride concentrations of 220-350 mg/L (milligrams per liter); ammonium-N (nitrogen) concentrations of 2.40 mg/L or less (except for one concentration of 18.4 mg/L); nitrate-N concentrations of 5.24 mg/L or less; and organic-N concentrations of 6.97 mg/L or less. Ground water would be enriched in chloride and diluted in inorganic-N from mixing with basin seepage. Fecal Coliform bacteria, although abundant in the basin wastewater, were present in very small amounts in the seepage. Total seepage flow from the site B basin generally ranged from 400 to 2,200 gal/d except during 1-month and 3-month periods when the flow ranged from about 3,800 to 6,200 gal/d. Seepage flow in areal units generally ranged from about 0.025 to 0.15 in./d, and, as at the site A basin, exceeded the MPCA recommended maximum design rate of 0.018 in./d. Seepage flow in areal units generally correlated with the flow in gal/d except through the sidewalls when the basin was unfilled. Except during the first three months of the study, seepage flow was greater through the sidewalls than through the bottom. Seepage from the site B basin (based on 10 samples each from the bottom and sidewall) had chloride concentrations of 11 to 100 mg/L; ammonium-N concentrations of 2.58 mg/L or less; nitrate-N concentrations of 25.7 mg/L or less (except for one concentration of 146 mg/L); and organic-N concentrations of 0.92 mg/L or less. Nitrate-N concentrations in the seepage exceeded the U.S. Environmental Protection Agency (1996). MCL (maximum contaminant level) of 10 mg/L in 17 of 22 samples. Background ground-water quality, however, indicated that nitrate-N concentrations were greater than the MCL prior to operation of the basin. Fecal Coliform bacteria, as at the site A basin, were abundant in the basin wastewater, but not in the seepage.

Minnesota↗
USGS2011

Tracking nonpoint source nitrogen pollution in human-impacted watersheds

Nonpoint source nitrogen (N) pollution is a leading contributor to U.S. water quality impairments. We combined watershed N mass balances and stable isotopes to investigate fate and transport of nonpoint N in forest, agricultural, and urbanized watersheds at the Baltimore Long-Term Ecological Research site. Annual N retention was 55%, 68%, and 82% for agricultural, suburban, and forest watersheds, respectively. Analysis of δ 15 N-NO 3 – , and δ 18 O-NO 3 – indicated wastewater was an important nitrate source in urbanized streams during baseflow. Negative correlations between δ 15 N-NO 3 – and δ 18 O-NO 3 – in urban watersheds indicated mixing between atmospheric deposition and wastewater, and N source contributions changed with storm magnitude (atmospheric sources contributed ∼50% at peak storm N loads). Positive correlations between δ 15 N-NO 3 – and δ 18 O-NO 3 – in watersheds suggested denitrification was removing septic system and agriculturally derived N, but N from belowground leaking sewers was less susceptible to denitrification. N transformations were also observed in a storm drain (no natural drainage network) potentially due to organic carbon inputs. Overall, nonpoint sources such as atmospheric deposition, wastewater, and fertilizer showed different susceptibility to watershed N export. There were large changes in nitrate sources as a function of runoff, and anticipating source changes in response to climate and storms will be critical for managing nonpoint N pollution.

Environmental Science & Technology↗
USGS2020

Effect of stressors on the carrying capacity of spatially distributed metapopulations

Stressors such as antibiotics, herbicides, and pollutants are becoming increasingly common in the environment. The effects of stressors on populations are typically studied in homogeneous, nonspatial settings. However, most populations in nature are spatially distributed over environmentally heterogeneous landscapes with spatially restricted dispersal. Little is known about the effects of stressors in these more realistic settings. Here, we combine laboratory experiments with novel mathematical theory to rigorously investigate how a stressor’s physiological effect and spatial distribution interact with dispersal to influence population dynamics. We prove mathematically that if a stressor increases the death rate and/or simultaneously decreases the population growth rate and yield, a homogeneous distribution of the stressor leads to a lower total population size than if the same amount of the stressor was heterogeneously distributed. We experimentally test this prediction on spatially distributed populations of budding yeast ( Saccharomyces cerevisiae ). We find that the antibiotic cycloheximide increases the yeast death rate but reduces the growth rate and yield. Consistent with our mathematical predictions, we observe that a homogeneous spatial distribution of cycloheximide minimizes the total equilibrium size of experimental metapopulations, with the magnitude of the effect depending predictably on the dispersal rate and the geographic pattern of antibiotic heterogeneity. Our study has implications for assessing the population risk posed by pollutants, antibiotics, and global change and for the rational design of strategies for employing toxins to control pathogens and pests.

The American Naturalist↗
USGS2025

A critical perspective on the Society of Environmental Toxicology and Chemistry’s adherence to founding principles—Opportunities for the future

The Society of Environmental Toxicology and Chemistry (SETAC) is a global organization whose mission is the advancement of environmental science and the promotion of science-informed decision making. On SETAC’s 45th anniversary, the following question was raised: Are the 1979 founding principles of SETAC, multidisciplinary approaches to solving environmental problems, multisector engagement and scientific objectivity, still relevant to the fulfillment of its mission? In a special session held at the 45th Annual Meeting in Fort Worth, Texas, U.S., a critical evaluation of the founding principles was initiated by reviewing SETAC’s history and ongoing activities, and recommendations were made for the future. With few exceptions, participants appreciated SETAC’s purposeful efforts to approach challenging environmental issues through multisector balance, an approach that is unique amongst scientific societies. We recognized that scientists have biases and views of what they find important, regardless of employing organization, and that objectivity is best served by being aware of these biases and views. SETAC’s founding principles have stood the test of time and continue to provide a strong foundation for the Society’s mission, and with a few suggested improvements, will continue to be instrumental in guiding environmental science, stewardship and policy into the future. The significance of SETAC’s contribution of robust science grounded in reliable evidence and data was recognized as being especially crucial at this time of triple planetary crisis (climate change, pollution and biodiversity loss), compounded by rapid technological developments and geopolitical issues.

Environmental Toxicology and Chemistry↗
USGS2010

Review of Oceanographic and Geochemical Data Collected in Massachusetts Bay during a Large Discharge of Total Suspended Solids from Boston's Sewage-Treatment System and Ocean Outfall in August 2002

During the period August 14-23, 2002, the discharge of total suspended solids (TSS) from the Massachusetts Water Resources Authority sewage-treatment plant ranged from 32 to 132 milligrams per liter, causing the monthly average discharge to exceed the limit specified in the National Pollution Discharge Elimination System permit. Time-series monitoring data collected by the U.S. Geological Survey in western Massachusetts Bay were examined to evaluate changes in environmental conditions during and after this exceedance event. The rate of sediment trapping and the concentrations of near-bottom suspended sediment measured near the outfall in western Massachusetts Bay increased during this period. Because similar increases in sediment-trapping rate were observed in the summers of 2003 and 2004, however, the increase in 2002 cannot be definitively attributed to the increased TSS discharge. Concentrations of copper and silver in trapped sediment collected 10 and 20 days following the 2002 TSS event were elevated compared to those in pre-event samples. Maximum concentrations were less than 50 percent of toxicity guidelines. Photographs of surficial bottom sediments obtained before and after the TSS event do not show sediment accumulation on the sea floor. Concentrations of silver, Clostridium perfringens, and clay in surficial bottom sediments sampled 10 weeks after the discharge event at a depositional site 3 kilometers west of the outfall were unchanged from those in samples obtained before the event. Simulation of the TSS event by using a coupled hydrodynamic-wave-sediment-transport model could enhance understanding of these observations and of the effects of the exceedance on the local marine environment.

Open-File Report↗
USGS1998

Comparison of NPDES program findings for selected cities in the United States

The U.S. Environmental Protection Agency, under section 402 (p) of the Water Quality Act of 1987, has required municipalities with populations of more than 100,000 to obtain National Pollutant Discharge Elimination System (NPDES) permits for urban stormwater discharge. This regulation is intended to minimize pollutant loadings from urbanized areas and preserve the quality of streams that receive stormwater. To apply for a NPDES permit, a municipality must monitor the chemistry of stormwater from basins having residential, commercial, and industrial land uses, and estimate storm- and annual pollutant loads and event-mean concentrations of 12 selected properties and constituents. The properties and constituents include biochemical oxygen demand (BOD), chemical oxygen demand (COD), suspended solids, dissolved solids, total nitrogen, total ammonia plus organic nitrogen, total phosphorus, dissolved phosphorus, total recoverable cadmium, total recoverable copper, total recoverable lead, and total recoverable zinc. These estimates will be used by the municipalities to evaluate the magnitude of pollutant loadings and the ef ficiency of management strategies that are intended to reduce pollutant loads. As part of a national synthesis of the study units in the U.S. Geological Survey (USGS) NPDES program, data were compiled on concentrations of the 12 properties and constituents required for load calculations. This report presents a comparison of these data.

Fact Sheet↗
USGS2015

U.S. Geological Survey water-resources programs in New Mexico, FY 2015

The U.S. Geological Survey (USGS) has collected hydrologic information in New Mexico since 1889, beginning with the first USGS streamflow-gaging station in the Nation, located on the Rio Grande near Embudo, New Mexico. Water-resources information provided by the USGS is used by many government agencies for issuing flood warnings to protect lives and reduce property damage,managing water rights and interstate water use, protecting water quality and regulating pollution discharges, designing highways and bridges, planning, designing, and operating reservoirs and watersupply facilities, monitoring the availability of groundwater resources and forecasting aquifer response to human and environmental stressors, and prioritizing areas where emergency erosion mitigation or other protective measures may be necessary after a wildfire. For more than 100 years, the Cooperative Water Program has been a highly successful cost-sharing partnership between the USGS and water-resources agencies at the State, local, and tribal levels. It would be difficult to effectively accomplish the mission of the USGS without the contributions of the Cooperative Water Program.

New Mexico↗
USGS1976

An oilspill risk analysis for the Mid-Atlantic Outer Continental Shelf lease area

An oilspill risk analysis was conducted to determine relative environmental impacts of developing oil in different regions of the Mid-Atlantic Outer Continental Shelf lease area. The study analyzed probability of spills, likely path of pollutants from spills, and locations in space and time of recreational and biological resources likely to be vulnerable. These results are combined to yield estimates of the overall oilspill risk associated with development of the lease area. (Woodard-USGS)

Open-File Report↗
USGS1976

An oilspill risk analysis for the South Atlantic Outer Continental Shelf lease area

An oilspill risk analysis was conducted to determine relative environmental hazards of developing oil in different regions of the South Atlantic Outer Continental Shelf lease area. The study analyzed probability of spill occurrence, likely path of pollutants from spills, and locations in space and time of recreational and biological resources likely to be vulnerable, paying particular attention to "worst-case" conditions. These results are combined to yield estimates of the overall oilspill risk associated with development of the lease area.

South Atlantic outer continental shelf↗
USGS2021

Use of dissolved oxygen monitoring to evaluate phosphorus loading in Connecticut streams, 2015–18

The Connecticut Department of Energy and Environmental Protection (CT DEEP) has developed an interim phosphorus reduction strategy to establish water-quality-based phosphorus limits in nontidal freshwaters for industrial and municipal water pollution control facilities. A recommendation in the strategy included the addition of diurnal dissolved oxygen (DO) sampling to the sampling of diatom communities collected by CT DEEP. The chemistry data coupled with biological data will help to examine the effects of phosphorus loading in streams. The U.S. Geological Survey (USGS), in cooperation with the CT DEEP and New England Interstate Water Pollution Control Commission, implemented a summer DO monitoring program from 2015 to 2018 to examine the effects of phosphorus loading in streams. Continuous DO data were collected at 18 sites in streams with varying concentrations of phosphorus throughout the State of Connecticut. Discrete water-quality nutrient data were collected by the USGS at 11 of the 18 sites. All continuous and discrete data collected from June to September for the 4 years were examined for all sites. This report documents a pattern of diurnal DO for monitoring sites across 4 years and presents estimated daily gross primary productivity (GPP), ecosystem respiration (ER), and a standardized rate coefficient for gas exchange for selected streams. Relations of phosphorus concentrations to the diurnal DO response and stream metabolism are described. Interannual variability in average annual total phosphorus (TP) concentrations and maximum daily DO concentrations were evaluated among sites in years of the study. Streams identified as impaired by CT DEEP such as Naugatuck River at Beacon Falls (USGS station 01208500), Still River at Route 7 at Brookfield Center (USGS station 01201487), and Quinnipiac River at Wallingford (USGS station 01196500) had higher TP concentrations (greater than 0.10 milligram per liter [mg/L]) throughout the study. Reference streams considered unimpaired had lower concentrations of TP (less than 0.10 mg/L). The range in daily DO concentrations remained less than 4 mg/L for most of the sites during the study except for Naugatuck River at Beacon Falls and Still River at Route 7 at Brookfield Center. Daily GPP and ER were summarized for 11 sites using the maximum likelihood estimation model of the streamMetabolizer package in the R statistical program. The models indicated that most sites had an estimated negative net primary productivity, based on the daily estimates of GPP and ER, which indicates the systems are heterotrophic and dominated by respiration. The high variation of GPP and ER reported for several sites can be affected by many physical, chemical, and biological factors, including the abundance and community composition of phytoplankton, periphyton, and macrophyte algae present. The variability in mean GPP was similar to the variability in maximum DO concentrations when plotted against annual average TP concentrations for the maximum likelihood estimation model in streamMetabolizer. The concept that phosphorus loading can affect the stream metabolism requires more detailed knowledge of stream geomorphic variables (canopy cover, stream velocity, water depth) and algal communities to help improve the scientific basis for managing phosphorus loading.

Connecticut↗
USGS1984

Effects of storm-water runoff on water quality of the Edwards Aquifer near Austin, Texas

Analyses of samples collected from Barton Springs at approximately weekly Intervals and from Barton Creek and five wells in the Austin area during selected storm-runoff periods generally show that recharge during storm runoff resulted in significant temporal and area! variations in the quality of ground water in the recharge zone of the Edwards aquifer. Recharge during storm runoff resulted in significant increases of bacterial densities in the ground water. Densities of fecal coliform bacteria in samples collected from Barton Springs, the major point of ground-water discharge, ranged from less than 1 colony per 100 milliliters during dry weather in November 1981 and January and August 1982 to 6,100 colonies per 100 milliliters during a storm in May 1982. Densities of fecal streptococcal bacteria ranged from 1 colony per 100 miniliters during dry weather in December 1981 to 11,000 colonies per 100 miniliters during a storm in May 1982. Recharge during storm runoff resulted in significant decreases in the specific conductance and the concentration of total nitrate nitrogen in the ground water. Specific-conductance values of samples from Barton Springs ranged from 438 micromhos per centimeter at 25° Celsius after a storm in October 1981 to 682 micromhos after a relatively long period of deficient rainfall in September 1982. The specific-conductance values and, thus, the mineralization of the ground water in the recharge zone generally were inversely related to the quantity of recharge. Nitrate nitrogen was the most prevalent form of nitrogen in the ground water. Concentrations of total nitrate nitrogen in samples from Barton Springs ranged from 0.51 milligram per liter after a storm in October 1981 to 1.6 milligrams per liter during dry weather in February and September 1982. Although the values of these and other properties or constituents in ground water varied temporally and areally, available data indicate that the values of most of the major and minor elements in ground water in the recharge zone of the Edwards aquifer were significantly less than the primary maximum or secondary maximum contaminant levels set by the U.S. Environmental Protection Agency for public water systems. Bacteriological data for Barton Springs and selected wells indicate that the ground water in the aquifer is susceptible to bacterial pollution, especially during storm runoff. The water may require disinfection if used for drinking or culinary purposes.

Water-Resources Investigations Report↗
USGS2009

Applications of stable isotopes for regional to national-scale water quality and environmental monitoring programs

Isotopes are a potentially powerful component of monitoring and assessment programs aimed at quantifying and mitigating alterations to environments from human activities. In particular, isotopic techniques have proved useful for tracing sources and sinks of various pollutants in large river basins, wetlands, and airsheds. Many of these studies have been conducted at the regional to national scale by building on existing large-scale water, air, and ecological monitoring programs managed by federal and state agencies, and demonstrate the usefulness of isotopes as a complement to standard chemical and hydrological mass balance methods. This chapter presents an overview of how nitrate, particulate organic matter, and water isotopes can be used to interpret spatial patterns and temporal changes in pollution sources, biogeochemical processes, and ecosystem function in watersheds, at the regional to national scale. Examples from several recent and ongoing studies are presented. From the insights developed using varied sampling strategies and isoscapes, we suggest guidelines for future studies in biologically active and human-impacted rivers.

Book chapter↗
USGS1980

Final executive summary report; environmental studies, southeastern United States Atlantic Outer Continental Shelf, 1977; geology

Starting in mid 1976 and continuing into 1977 a variety of geological studies were carried out by the U. S. Geological Survey on the southeastern U. S. Atlantic Continental Margin to assess conditions and hazards that might cause or distribute oil spills or other pollutants, or constrain petroleum exploration or development of the area. These detailed investigations were requested and funded by the Bureau of Land Management to carry out its responsibility under the Outer Continental Shelf (OCS) Lands Act of 1969. Because of the energy crisis the decision had been made to lease on the southeastern continental shelf. A variety of studies had to be mounted quickly for input into decisions concerning the environment that would affect or constrain which lease tracks would be offered. The first lease sale, Lease Sale 43, took place in March 1978, and the environmental information on which this lease sale was based came in part from this initial effort and in part from a wide variety of pertinent data assembled from the literature by the Bureau of Land Management's Environmental Assessment Division. The compilation of relevant data for the Environmental Impact Statement for Lease Sale 43 also pointed up deficiencies in environmental knowledge in a number of areas. The Bureau of Land Management's environmental program for the Southeast Atlantic OCS was initiated to fill gaps in the environmental data base and to detect and assess impacts from oil and gas exploration and production.

Florida, North Carolina, South Carolina↗
USGS2007

Water Budgets: Foundations for Effective Water-Resources and Environmental Management

INTRODUCTION Water budgets provide a means for evaluating availability and sustainability of a water supply. A water budget simply states that the rate of change in water stored in an area, such as a watershed, is balanced by the rate at which water flows into and out of the area. An understanding of water budgets and underlying hydrologic processes provides a foundation for effective water-resource and environmental planning and management. Observed changes in water budgets of an area over time can be used to assess the effects of climate variability and human activities on water resources. Comparison of water budgets from different areas allows the effects of factors such as geology, soils, vegetation, and land use on the hydrologic cycle to be quantified. Human activities affect the natural hydrologic cycle in many ways. Modifications of the land to accommodate agriculture, such as installation of drainage and irrigation systems, alter infiltration, runoff, evaporation, and plant transpiration rates. Buildings, roads, and parking lots in urban areas tend to increase runoff and decrease infiltration. Dams reduce flooding in many areas. Water budgets provide a basis for assessing how a natural or human-induced change in one part of the hydrologic cycle may affect other aspects of the cycle. This report provides an overview and qualitative description of water budgets as foundations for effective water-resources and environmental management of freshwater hydrologic systems. Perhaps of most interest to the hydrologic community, the concepts presented are also relevant to the fields of agriculture, atmospheric studies, meteorology, climatology, ecology, limnology, mining, water supply, flood control, reservoir management, wetland studies, pollution control, and other areas of science, society, and industry. The first part of the report describes water storage and movement in the atmosphere, on land surface, and in the subsurface, as well as water exchange among these compartments. Our ability to measure these phenomena and inherent uncertainties in measurement techniques also are discussed. The latter part of the report presents a number of case studies that illustrate how water-budget studies are conducted, documents how human activities affect water budgets, and describes how water budgets are used to address water and environmental issues.

Circular↗
USGS2002

Llano Grande Lake bottom sediments: A chronicle of water-quality changes in the Arroyo Colorado, South Texas, 1989-2001

The Arroyo Colorado, an ancient channel of the Rio Grande, extends 90 miles from Mission, Tex., to the Laguna Madre. The Arroyo Colorado flows through areas of intense agricultural cultivation and through important habitat for migrating birds and other wildlife, including several wildlife sanctuaries and refuges. The above-tidal segment of the Arroyo Colorado is included in the State of Texas 2000 Clean Water Act 303(d)1 list in part because of elevated concentrations of the hydrophobic legacy pollutants DDE (a DDT breakdown product), chlordane, and toxaphene in fish tissue. This report addresses three questions: Do legacy pollutants (organochlorine compounds, major and trace elements) occur in the Arroyo Colorado at present and at what concentrations? How has the occurrence of selected legacy pollutants in the Arroyo Colorado changed over time? Are current concentrations of legacy pollutants in bottom sediments at levels of concern for the health of aquatic biota? To answer these questions, the U.S. Geological Survey (USGS), in cooperation with the U.S. Environmental Protection Agency (USEPA), collected and analyzed a sediment core from Llano Grande Lake on the Arroyo Colorado (fig. 1). Sediment cores can be used to reconstruct historical trends in concentrations of hydrophobic contaminants (Eisenreich and others, 1989; Van Metre and others, 1997, 2000). The lake is part of the Rio Grande delta drainage system (fig. 1). The lake is 6 miles long and has a maximum width of 600 feet.

Texas↗
USGS2017

Sea turtles, light pollution, and citizen science: A preliminary report

Sea turtles are an important ecological resource for Gulf Islands National Seashore’s (Gulf Islands) waters and shorelines. Regionally, sea turtles face anthropogenic threats from situations such as entanglement in fishing gear and ingestion of marine debris, as well as possible changes in sex ratios due to increasing temperatures related to human-induced global warming. Locally, light pollution from residential, commercial, and industrial neighborhoods from nearby cities impacts the entirety of Gulf Islands, which spans 160 miles along the Gulf Coast, from Florida to Mississippi, and includes critical habitat for threatened and endangered sea turtles. Because light pollution has been hypothesized to negatively impact sea turtle nesting and hatchling survival, Gulf Islands undertook an effort to understand the relationship between light pollution and sea turtles and create unique educational and outreach opportunities by launching a citizen science program called Turtle Teens Helping in the Seashore (Turtle THIS). At the onset, the Turtle THIS program had two primary goals: quantify the association between light pollution and sea turtle nesting and hatching events using rigorous scientific methods; and initiate a citizen science volunteer program to provide youth with hands-on science and environmental stewardship roles, where they also gain employable skills and career opportunities. With multiple scientific hypotheses to consider, the development of a citizen science program became crucial. Such circumstances allowed Turtle THIS to grow a volunteer and intern program, quantify hypothesized light effects on sea turtles through developed methods, and begin to gather preliminary findings.

Florida↗
USGS2014

Lacustrine responses to decreasing wet mercury deposition rates: results from a case study in northern Minnesota

We present a case study comparing metrics of methylmercury (MeHg) contamination for four undeveloped lakes in Voyageurs National Park to wet atmospheric deposition of mercury (Hg), sulfate (SO 4 –2 ), and hydrogen ion (H + ) in northern Minnesota. Annual wet Hg, SO 4 –2 , and H + deposition rates at two nearby precipitation monitoring sites indicate considerable decreases from 1998 to 2012 (mean decreases of 32, 48, and 66%, respectively). Consistent with decreases in the atmospheric pollutants, epilimnetic aqueous methylmercury (MeHg aq ) and mercury in small yellow perch (Hg fish ) decreased in two of four lakes (mean decreases of 46.5% and 34.5%, respectively, between 2001 and 2012). Counter to decreases in the atmospheric pollutants, MeHg aq increased by 85% in a third lake, whereas Hg fish increased by 80%. The fourth lake had two disturbances in its watershed during the study period (forest fire; changes in shoreline inundation due to beaver activity); this lake lacked overall trends in MeHg aq and Hg fish . The diverging responses among the study lakes exemplify the complexity of ecosystem responses to decreased loads of atmospheric pollutants.

Minnesota↗
USGS2020

Spatial distribution of heavy metals in the West Dongting Lake floodplain, China

The protection of Dongting Lake is important because it is an overwintering and migration route for many rare and endangered birds of East Asia and Australasia, but an assessment of heavy metal contamination in West Dongting Lake is lacking. A total of 75 sediment samples (five sites x three sediment depths x five repeats) were collected in West Dongting Lake in January 2017 to assess the spatial distribution and ecological risk of heavy metal in West Dongting Lake. Heavy metal values varied by sediment depth including As, Cd, Zn, and Cu, with depth giving an indication of recent vs. historical deposition. The major input of Hg, Cu, Ni may come from continued anthropogenic activities related to regional industrial activities within Yuan River and Li River whereas, the major sources of spread Cd pollution may be from agricultural fertilizers.

West Dongting Lake floodplain↗