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At least 325 records · Page 18Linked to original sources
USGS2016

Adapting inland fisheries management to a changing climate

Natural resource decision makers are challenged to adapt management to a changing climate while balancing short-term management goals with long-term changes in aquatic systems. Adaptation will require developing resilient ecosystems and resilient management systems. Decision makers already have tools to develop or ensure resilient aquatic systems and fisheries such as managing harvest and riparian zones. Because fisheries management often interacts with multiple stakeholders, adaptation strategies involving fisheries managers and other partners focused on land use, policy, and human systems, coupled with long-term monitoring, are necessary for resilient systems. We show how agencies and organizations are adapting to a changing climate in Minnesota and Ontario lakes and Montana streams. We also present how the Florida Fish and Wildlife Commission created a management structure to develop adaptation strategies. These examples demonstrate how organizations and agencies can cope with climate change effects on fishes and fisheries through creating resilient management and ecological systems.

Fisheries↗
USGS2008

Xenobiotic-induced apoptosis: significance and potential application as a general biomarker of response

The process of apoptosis, often coined programmed cell death, involves cell injury induced by a variety of stimuli including xenobiotics and is morphologically, biochemically, and physiologically distinct from necrosis. Apoptotic death is characterized by cellular changes such as cytoplasm shrinkage, chromatin condensation, and plasma membrane asymmetry. This form of cell suicide is appealing as a general biomarker of response in that it is expressed in multiple cell systems (e.g. immune, neuronal, hepatal, intestinal, dermal, reproductive), is conserved phylogenetically (e.g. fish, rodents, birds, sheep, amphibians, roundworms, plants, humans), is modulated by environmentally relevant levels of chemical contaminants, and indicates a state of stress of the organism. Further, apoptosis is useful as a biomarker as it serves as a molecular control point and hence may provide mechanistic information on xenobiotic stress. Studies reviewed here suggest that apoptosis is a sensitive and early indicator of acute and chronic chemical stress, loss of cellular function and structure, and organismal health. Examples are provided of the application of this methodology in studies of health of lake trout (Salvelinus namaycush) in the Laurentian Great Lakes.

Biomarkers↗
USGS2010

Microbial degradation of plant leachate alters lignin phenols and trihalomethane precursors

Although the importance of vascular plant-derived dissolved organic carbon (DOC) in freshwater systems has been studied, the role of leached DOC as precursors of disinfection byproducts (DBPs) during drinking water treatment is not well known. Here we measured the propensity of leachates from four crops and four aquatic macrophytes to form trihalomethanes (THMs)—a regulated class of DBPs—before and after 21 d of microbial degradation. We also measured lignin phenol content and specific UV absorbance (SUVA 254 ) to test the assumption that aromatic compounds from vascular plants are resistant to microbial degradation and readily form DBPs. Leaching solubilized 9 to 26% of total plant carbon, which formed 1.93 to 6.72 mmol THM mol C -1 However, leachate DOC concentrations decreased by 85 to 92% over the 21-d incubation, with a concomitant decrease of 67 to 92% in total THM formation potential. Carbon-normalized THM yields in the residual DOC pool increased by 2.5 times on average, consistent with the preferential uptake of nonprecursor material. Lignin phenol concentrations decreased by 64 to 96% over 21 d, but a lack of correlation between lignin content and THM yields or SUVA 254 suggested that lignin-derived compounds are not the source of increased THM precursor yields in the residual DOC pool. Our results indicate that microbial carbon utilization alters THM precursors in ecosystems with direct plant leaching, but more work is needed to identify the specific dissolved organic matter components with a greater propensity to form DBPs and affect watershed management, drinking water quality, and human health.

Journal of Environmental Quality↗
USGS2009

Monitoring for Pesticides in Groundwater and Surface Water in Nevada, 2008

Commercial pesticide applicators, farmers, and homeowners apply about 1 billion pounds of pesticides annually to agricultural land, non-crop land, and urban areas throughout the United States (Gilliom and others, 2006, p. 1). The U.S. Environmental Protection Agency (USEPA) defines a pesticide as any substance used to kill or control insects, weeds, plant diseases, and other pest organisms. Although there are important benefits from the proper use of pesticides, like crop protection and prevention of human disease outbreaks, there are also risks. One risk is the contamination of groundwater and surface-water resources. Data collected during 1992-2001 from 51 major hydrologic systems across the United States indicate that one or more pesticide or pesticide breakdown product was detected in more than 50 percent of 5,057 shallow (less than 20 feet below land surface) wells and in all of the 186 stream sites that were sampled in agricultural and urban areas (Gilliom and others, 2006, p. 2-4). Pesticides can contaminate surface water and groundwater from both point sources and non-point sources. Point sources are from specific locations such as spill sites, disposal sites, pesticide drift during application, and application of pesticides to control aquatic pests. Non-point sources represent the dominant source of surface water and groundwater contamination and may include agricultural and urban runoff, erosion, leaching from application sites, and precipitation that has become contaminated by upwind applications. Pesticides typically enter surface water when rainfall or irrigation exceeds the infiltration capacity of soil and resulting runoff then transports pesticides to streams, rivers, and other surface-water bodies. Contamination of groundwater may result directly from spills near poorly sealed well heads and from pesticide applications through improperly designed or malfunctioning irrigation systems that also are used to apply pesticides (chemigation; Carpenter and Johnson, 1997). Groundwater contamination also may come indirectly by the percolation of agricultural and urban irrigation water through soil layers and into groundwater and from pesticide residue in surface water, such as drainage ditches, streams, and municipal wastewater. To protect surface water and groundwater from pesticide contamination, the USEPA requires that all states establish a pesticide management plan. The Nevada Department of Agriculture (NDOA), with assistance from the USEPA, developed a management program of education (Hefner and Donaldson, 2006), regulation (Johnson and others, 2006), and monitoring (Pennington and others, 2001) to protect Nevada's water resources from pesticide contaminants. Sampling sites are located in areas where urban or agricultural pesticide use may affect groundwater, water bodies, endangered species, and other aquatic life. Information gathered from these sites is used by NDOA to help make regulatory decisions that will protect human and environmental health by reducing and eliminating the occurrence of pesticide contamination. This fact sheet describes current (2008) pesticide monitoring of groundwater and streams by the NDOA in Nevada and supersedes Pennington and others (2001).

Fact Sheet↗
USGS2016

Hepeviruses of fish

Originally reported from California, the cutthroat trout virus (CTV) has now been isolated from eight species of salmonids in North America. Early work focused on the replication and physical characteristics of the small, round virus, but not until 20 years later was it determined to be most closely related to viruses causing hepatitis E in humans or infecting avian and mammalian hosts. The genome of CTV consists of 7269 nucleotides of positive-sense, single-stranded RNA with a genome organization similar to other members of the family Hepeviridae , although the amino acid sequence identity appears low enough to support creation of a novel genus. While CTV has not been associated with acute disease in fish, the virus was able to form persistently infected cell cultures that may aid research in treatment of hepatitis E-like viruses affecting humans or other animals. Interestingly, trout exposed to CTV were protected for about a month against subsequent exposure to Infectious hematopoietic necrosis virus . Replicating agents suspected to be CTV can be confirmed by polymerase chain reaction (PCR) and sequencing.

Book chapter↗
USGS2023

Frequent transitions in mating-type locus chromosomal organization in Malassezia and early steps in sexual reproduction

Fungi in the basidiomycete genus Malassezia are the most prevalent eukaryotic microbes resident on the skin of human and other warm-blooded animals and have been implicated in skin diseases and systemic disorders. Analysis of Malassezia genomes revealed that key adaptations to the skin microenvironment have a direct genomic basis, and the identification of mating/meiotic genes suggests a capacity to reproduce sexually, even though no sexual cycle has yet been observed. In contrast to other bipolar or tetrapolar basidiomycetes that have either two linked mating-type-determining ( MAT ) loci or two MAT loci on separate chromosomes, in Malassezia species studied thus far the two MAT loci are arranged in a pseudobipolar configuration (linked on the same chromosome but capable of recombining). By generating additional chromosome-level genome assemblies, and an improved Malassezia phylogeny, we infer that the pseudobipolar arrangement was the ancestral state of this group and revealed six independent transitions to tetrapolarity, seemingly driven by centromere fission or translocations in centromere-flanking regions. Additionally, in an approach to uncover a sexual cycle, Malassezia furfur strains were engineered to express different MAT alleles in the same cell. The resulting strains produce hyphae reminiscent of early steps in sexual development and display upregulation of genes associated with sexual development as well as others encoding lipases and a protease potentially relevant for pathogenesis of the fungus. Our study reveals a previously unseen genomic relocation of mating-type loci in fungi and provides insight toward the identification of a sexual cycle in Malassezia , with possible implications for pathogenicity.

PNAS↗
USGS2009

Groundwater-Quality Assessment, Pike County, Pennsylvania, 2007

Pike County, a 545 square-mile area in northeastern Pennsylvania, has experienced the largest relative population growth of any county in the state from 1990 to 2000 and its population is projected to grow substantially through 2025. This growing population may result in added dependence and stresses on water resources, including the potential to reduce the quantity and degrade the quality of groundwater and associated stream base flow with changing land use. Groundwater is the main source of drinking water in the county and is derived primarily from fractured-rock aquifers (shales, siltstones, and sandstones) and some unconsolidated glacial deposits that are recharged locally from precipitation. The principal land uses in the county as of 2005 were public, residential, agricultural, hunt club/private recreational, roads, and commercial. The public lands cover a third of the county and include national park, state park, and other state lands, much of which are forested. Individual on-site wells and wastewater disposal are common in many residential areas. In 2007, the U.S. Geological Survey, in cooperation with the Pike County Conservation District, began a study to provide current information on groundwater quality throughout the county that will be helpful for water-resource planning. The countywide reconnaissance assessment of groundwater quality documents current conditions with existing land uses and may serve as a baseline of groundwater quality for future comparison. Twenty wells were sampled in 2007 throughout Pike County to represent groundwater quality in the principal land uses (commercial, high-density and moderate-density residential with on-site wastewater disposal, residential in a sewered area, pre-development, and undeveloped) and geologic units (five fractured-rock aquifers and one glacial unconsolidated aquifer). Analyses selected for the groundwater samples were intended to identify naturally occurring constituents from the aquifer or constituents introduced by human activities that pose a health risk or otherwise were of concern in groundwater in the county. The analyses included major ions, nutrients, selected trace metals, volatile organic compounds (VOCs), selected organic wastewater compounds, gross alpha-particle and gross beta-particle activity, uranium, and radon-222. Analyses of the 20 samples were primarily for dissolved constituents, but six samples were analyzed for both dissolved and total metals. Results of the 2007 sampling indicated few water-quality problems, although concentrations of some constituents indicated influence of human activities on groundwater. No constituent analyzed exceeded any primary drinking-water standard or maximum contaminant level (MCL) established by the U.S. Environmental Protection Agency. Radon-222 levels were greater than, or equal to, the proposed MCL of 300 picocuries per liter (pCi/L) in water from 15 (75 percent) of the 20 wells. Radon-222 levels did not exceed the alternative MCL of 4,000 pCi/L in any groundwater sample. Radon-222 is naturally occurring, and the greatest concentrations (up to 2,650 pCi/L) were in water samples from wells in members of the Catskill Formation, a fractured-rock aquifer. The dissolved arsenic concentration of 3.9 micrograms per liter (ug/L) in one sample was greater than the health-advisory (HA) level of 2 ug/L but less than the MCL of 10 ug/L. Recommended or secondary maximum contaminant levels (SMCLs) were exceeded for pH, dissolved iron, and dissolved manganese. In six samples analyzed for dissolved and total concentrations of selected metals, total concentrations commonly were much greater than dissolved concentrations of iron, and to a lesser degree, for arsenic, lead, copper, and manganese. Concentrations of iron above the SMCL of 300 ug/L may be more widespread in the county for particulate iron than for dissolved iron. The total arsenic concentration in one of the six samples was greater than the HA level of

Scientific Investigations Report↗
USGS1987

Effect of urbanization on the water resources of eastern Chester County, Pennsylvania

The effects of human activity on the water resources of a 207-square-mile area of eastern Chester County was evaluated. The most serious consequence of urbanization is the contamination of ground water by volatile organic compounds, which were detected in 39 percent of the 70 wells sampled. As many as nine compounds were found in one water sample, and the concentration of total volatile organic compounds was as high as 17,400 ug/L (micrograms per liter). In the Chester Valley, volatile organic compounds are moving down the hydraulic gradient caused by quarry dewatering. Movement through the quarries reduces concentrations of these compounds and removes most of them. Phenol was detected in 28 percent of 54 wells sampled, with concentrations up to 7 ug/L. Metals, except for iron and manganese, and other trace constituents generally are not a water-quality problem. However, ground water in an area in Chester Valley has been contaminated by concentrations of boron as high as 20,000 ug/L and lithium as high as 13,000 ug/L. The ground water discharges to Valley Creek, where concentrations of boron are as high as 130 ug/L and lithium as high as 800 ug/L. Concentrations of chloride as high as 2,100 mg/L (milligrams per liter) were found in a well at a former highway salt storage site. Wells completed in carbonate rock downgradient from the Pennsylvania Turnpike had chloride concentrations as high as 350 mg/L. The base-neutral organic compounds bis(2-ethylhexyl) phthalate, di-n-butyl phthalate, and 1,2-dichlorobenzene, and the pesticides alachlor, aldrian, diazanon, DDD, DDT, dieldrin, methyl parathion, picloram, and 2,4-D were detected in a few water samples in low concentrations, However, these organic compounds do not present a widespread water-quality problem. Neither acid organic compounds nor polychlorinated napthalenes (PCN) were detected in ground water. The growth of public water and sewer systems has resulted in a significant interbasin transfer of water. Estimates for 1984 range from a net loss of 630 million gallons in the Valley Creek basin to a net gain of 783 million gallons in the Chester Creek basin. The quantity of wastewater discharged from treatment plants generally correlates well with the altitude of the water table and poorly with water use or precipitation, indicating substantial ground-water infiltration. Estimated ground-water infiltration to the West Goshen treatment plant for 1980-84 was 0.8 cubic feet per square mile, or 10 percent of the long-term average flow of Chester Creek. Estimated ground-water infiltration to the Valley Forge sewer system was as high as 4.9 million gallons per day. Dewatering operations at two active quarries in Chester Valley have lowered water levels locally and increased the range of the fluctuation of the local water table. The spread of the cones of depression caused by quarry pumping is limited by geologic and hydrologic controls. Pumping of high-capacity wells in Chester Valley has caused small local cones of depression and may have caused some reaches of Valley Creek or its tributaries to lose water. One of the greatest effects of human activity on the surface-water system has been the accumulation of organic compounds, particularly PCB and pesticides, on stream-bottom material. PCB, DDE, and dieldrin were found in bottom material from all eight streams sampled. Land-use changes in 10 selected subbasins were quantified and related to stream-benthic invertebrate diversity index. from 1970-80, the diversity index increased at all sites. Subbasins that had a greater change in land use had a greater increase in diversity index. The increase may be due to the banning of certain pesticides such as DDT, a decreasing use of pesticides in urbanizing subbasins, or flushing or burial of older pesticide-contaminated sediment.

Pennsylvania↗
USGS2024

Coastal wetlands in the Anthropocene

We review the functioning and sustainability of coastal marshes and mangroves. Urbanized humans have a 7,000-year-old enduring relationship to coastal wetlands. Wetlands include marshes, salt flats, and saline and freshwater forests. Coastal wetlands occur in all climate zones but are most abundant in deltas. Mangroves are tropical, whereas marshes occur from tropical to boreal areas. Quantification of coastal wetland areas has advanced in recent years but is still insufficiently accurate. Climate change and sea-level rise are predicted to lead to significant wetland losses and other impacts on coastal wetlands and the humans associated with them. Landward migration and coastal retreat are not expected to significantly reduce coastal wetland losses. Nitrogen watershed inputs are unlikely to alter coastal marsh stability because watershed loadings are mostly significantly lower than those in fertilization studies that show decreased belowground biomass and increased decomposition of soil organic matter. Blue carbon is not expected to significantly reduce climate impacts. The high values of ecosystem goods and services of wetlands are expected to be reduced by area losses. Humans have had strong impacts on coastal wetlands in the Holocene, and these impacts are expected to increase in the Anthropocene.

Annual Review of Environment and Resources↗
USGS2011

Stopover habitats of spring migrating surf scoters in southeast Alaska

Habitat conditions and nutrient reserve levels during spring migration have been suggested as important factors affecting population declines in waterfowl, emphasizing the need to identify key sites used during spring and understand habitat features and resource availability at stopover sites. We used satellite telemetry to identify stopover sites used by surf scoters migrating through southeast Alaska during spring. We then contrasted habitat features of these sites to those of random sites to determine habitat attributes corresponding to use by migrating scoters. We identified 14 stopover sites based on use by satellite tagged surf scoters from several wintering sites. We identified Lynn Canal as a particularly important stopover site for surf scoters originating throughout the Pacific winter range; approximately half of tagged coastally migrating surf scoters used this site, many for extended periods. Stopover sites were farther from the mainland coast and closer to herring spawn sites than random sites, whereas physical shoreline habitat attributes were generally poor predictors of site use. The geography and resource availability within southeast Alaska provides unique and potentially critical stopover habitat for spring migrating surf scoters. Our work identifies specific sites and habitat resources that deserve conservation and management consideration. Aggregations of birds are vulnerable to human activity impacts such as contaminant spills and resource management decisions. This information is of value to agencies and organizations responsible for emergency response planning, herring fisheries management, and bird and ecosystem conservation.

Journal of Wildlife Management↗
USGS2018

Evaluating the relationship among wetland vertical development, elevation capital, sea-level rise and tidal marsh sustainability

Accelerating sea-level rise and human impacts to the coast (e.g., altered sediment supply and hydrology, nutrient loading) influence the accumulation of sediment and organic matter, and thereby impact the ability of coastal tidal wetlands to maintain an elevation consistently within the vegetation growth range. Critical components of marsh sustainability are the marsh elevation within the vegetation growth range (elevation capital) and the rates of marsh surface elevation change and relative sea-level rise. The relationship among these factors and their combined influence on marsh integrity were evaluated by comparing trends in surface elevation change on five salt marsh sites located on three marsh islands in Jamaica Bay, NY, USA. All marsh sites were located in a similar physical setting (i.e., tidal range, sea-level rise rate, sediment supply). The structural integrity of the marshes ranged from densely vegetated (high integrity) to severely deteriorated (low integrity) with elevation capital ranging from high to low, respectively, and included a deteriorating marsh site that was partially restored. Two marshes with high elevation capital maintained their relative position high within the tidal range through a combination of surface sediment deposition and shallow subsurface expansion, and kept pace with local sea-level rise. A marsh with moderate elevation capital showed signs of flooding stress and was deteriorating, but managed to keep pace with local sea-level rise. The deteriorated marsh gained no elevation over the 14-year study and was located too low within the tidal range to support continuous coverage of salt marsh vegetation. Elevation gain in the restored marsh initially lagged behind sea-level rise for 8 years, but the elevation trend recovered and kept pace with sea-level rise for the last 5 years. A conceptual model is presented that describes the relationship among elevation capital, and rates of marsh elevation gain and sea-level rise. Note that a search for factors influencing wetland loss should focus on process changes to marsh vertical development (e.g., sediment supply, vegetation growth) and climate change effects (e.g., sea-level and temperature rise) that can cause elevation gain to lag behind sea-level rise, and these occur prior to the onset of marsh deterioration.

New York↗
USGS2007

A review of land–sea coupling by groundwater discharge of nitrogen to New England estuaries: Mechanisms and effects

Hydrologists have long been concerned with the interface of groundwater flow into estuaries, but not until the end of the last century did other disciplines realize the major role played by groundwater transport of nutrients to estuaries. Mass balance and stable isotopic data suggest that land-derived NO 3 , NH 4 , and dissolved organic N do enter estuaries in amounts likely to affect the function of the receiving ecosystem. Because of increasing human occupancy of the coastal zone, the nutrient loads borne by groundwater have increased in recent decades, in spite of substantial interception of nutrients within the land and aquifer components of watersheds. Groundwater-borne nutrient loads have increased the N content of receiving estuaries, increased phytoplankton and macroalgal production and biomass, decreased the area of seagrasses, and created a cascade of associated ecological changes. This linkage between land use and eutrophication of estuaries occurs in spite of mechanisms, including uptake of land-derived N by riparian vegetation and fringing wetlands, “unloading” by rapid water removal, and direct N inputs to estuaries, that tend to uncouple the effects of land use on receiving estuaries. It can be expected that as human activity on coastal watersheds continues to increase, the role of groundwater-borne nutrients to the receiving estuary will also increase.

New England↗
USGS2019

Stratification of reactivity determines nitrate removal in groundwater

Biogeochemical reactions occur unevenly in space and time, but this heterogeneity is often simplified as a linear average due to sparse data, especially in subsurface environments where access is limited. For example, little is known about the spatial variability of groundwater denitrification, an important process in removing nitrate originating from agriculture and land use conversion. Information about the rate, arrangement, and extent of denitrification is needed to determine sustainable limits of human activity and to predict recovery time frames. Here, we developed and validated a method for inferring the spatial organization of sequential biogeochemical reactions in an aquifer in France. We applied it to five other aquifers in different geological settings located in the United States and compared results among 44 locations across the six aquifers to assess the generality of reactivity trends. Of the sampling locations, 79% showed pronounced increases of reactivity with depth. This suggests that previous estimates of denitrification have underestimated the capacity of deep aquifers to remove nitrate, while overestimating nitrate removal in shallow flow paths. Oxygen and nitrate reduction likely increases with depth because there is relatively little organic carbon in agricultural soils and because excess nitrate input has depleted solid phase electron donors near the surface. Our findings explain the long-standing conundrum of why apparent reaction rates of oxygen in aquifers are typically smaller than those of nitrate, which is energetically less favorable. This stratified reactivity framework is promising for mapping vertical reactivity trends in aquifers, generating new understanding of subsurface ecosystems and their capacity to remove contaminants.

Proceedings of the National Academy of Sciences↗
USGS2011

Ecosystem approach to inland fisheries: Research needs and implementation strategies

Inland fisheries are a vital component in the livelihoods and food security of people throughout the world, as well as contributing huge recreational and economic benefits. These valuable assets are jeopardized by lack of research-based understanding of the impacts of fisheries on inland ecosystems, and similarly the impact of human activities associated with inland waters on fisheries and aquatic biodiversity. To explore this topic, an international workshop was organized in order to examine strategies to incorporate fisheries into ecosystem approaches for management of inland waters. To achieve this goal, a new research agenda is needed that focuses on: quantifying the ecosystem services provided by fresh waters; quantifying the economic, social and nutritional benefits of inland fisheries; improving assessments designed to evaluate fisheries exploitation potential; and examining feedbacks between fisheries, ecosystem productivity and aquatic biodiversity. Accomplishing these objectives will require merging natural and social science approaches to address coupled social-ecological system dynamics. ?? 2010 The Royal Society.

Conference Paper↗
USGS2008

Phase shift from a coral to a corallimorph-dominated reef associated with a shipwreck on Palmyra atoll

Coral reefs can undergo relatively rapid changes in the dominant biota, a phenomenon referred to as phase shift. Various reasons have been proposed to explain this phenomenon including increased human disturbance, pollution, or changes in coral reef biota that serve a major ecological function such as depletion of grazers. However, pinpointing the actual factors potentially responsible can be problematic. Here we show a phase shift from coral to the corallimorpharian Rhodactis howesii associated with a long line vessel that wrecked in 1991 on an isolated atoll (Palmyra) in the central Pacific Ocean. We documented high densities of R. howesii near the ship that progressively decreased with distance from the ship whereas R. howesii were rare to absent in other parts of the atoll. We also confirmed high densities of R. howesii around several buoys recently installed on the atoll in 2001. This is the first time that a phase shift on a coral leef has been unambiguously associated with man-made structures. This association was made, in part, because of the remoteness of Palmyra and its recent history of minimal human habitation or impact. Phase shifts can have long-term negative ramification for coral reefs, and eradication of organisms responsible for phase shifts in marine ecosystems can be difficult, particularly if such organisms cover a large area. The extensive R. howesii invasion and subsequent loss of coral reef habitat at Palmyra also highlights the importance of rapid removal of shipwrecks on corals reefs to mitigate the potential of reef overgrowth by invasives.

Palmyra Atoll↗
USGS2006

Seasonal persistence and population characteristics of Escherichia coli and entercocci in deep backshore sand of two freshwater beaches

We studied the shoreward and seasonal distribution of E. coli and enterococci in sand (at the water table) at two southern Lake Michigan beaches—Dunbar and West Beach (in Indiana). Deep, backshore sand (∼20 m inland) was regularly sampled for 15 months during 2002–2003. E. coli counts were not significantly different in samples taken at 5-m intervals from 0–40 m inland (P=0.25). Neither E. coli nor enterococci mean counts showed any correlation or differences between the two beaches studied. In laboratory experiments, E. coli readily grew in sand supplemented with lake plankton, suggesting that in situ E. coli growth may occur when temperature and natural organic sources are adequate. Of the 114 sand enterococci isolates tested, positive species identification was obtained for only 52 (46%), with E. faecium representing the most dominant species (92%). Genetic characterization by ribotyping revealed no distinct genotypic pattern (s) for E. coli , suggesting that the sand population was rather a mixture of numerous strains (genotypes). These findings indicate that E. coli and enterococci can occur and persist for extended periods in backshore sand at the groundwater table. Although this study was limited to two beaches of southern Lake Michigan, similar findings can be expected at other temperate freshwater beaches. The long-term persistence of these bacteria, perhaps independent of pollution events, complicates their use as indicator organisms. Further, backshore sand at the water table may act as a reservoir for these bacteria and potentially for human pathogens.

Michigan, Indiana↗
USGS2013

Concentrations of chloride and sodium in groundwater in New Hampshire from 1960 through 2011

Several studies from the 1970s and more recently (for example, Hall (1975), Daley and others (2009) and Mullaney (2009)) have found that concentrations of chloride and sodium in groundwater in New Hampshire have increased during the past 50 years. Increases likely are related to road salt and other anthropogenic sources, such as septic systems, wastewater, and contamination from landfills and salt-storage areas. According to water-quality data reported to the New Hampshire Department of Environmental Services (NHDES), about 100 public water systems (5 percent) in 2010 had at least one groundwater sample with chloride concentrations that were equal to or exceeded the U.S. Environmental Protection Agency (USEPA) secondary maximum contaminant level (SMCL) of 250 mg/L before the water was treated for public consumption. The SMCL for chloride is a measurement of potential cosmetic or aesthetic effects of chloride in water. High concentrations of chloride and sodium in drinking-water sources can be costly to remove. A new cooperative study between the U.S. Geological Survey (USGS) and the NHDES (Medalie, 2012) assessed chloride and sodium levels in groundwater in New Hampshire from the 1960s through 2011. The purpose of the study was to integrate all data on concentrations of chloride and sodium from groundwater in New Hampshire available from various Federal and State sources, including from the NHDES, the New Hamsphire Department of Health and Human Services, the USGS, and the U.S. Environmental Protection SurveyAgency (USEPA), for public and private (domestic) wells and to organize the data into a database. Medalie (2012) explained the many assumptions and limitations of disparate data that were collected to meet wide-ranging objectives. This fact sheet summarizes the most important findings of the data.

New Hampshire↗