USGS Science⌕ Search

SEARCH · USGS Science

Results for “Environment and Resources”

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

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

At least 1,765 records · Page 98Linked to original sources
USGS1976

Effects of off-road vehicle use on the hydrology and landscape of arid environments in central and southern California

Two widely separated sites in California used for motorcycle hill-climbing were studied to evaluate the impact on the landscape and hydrology. At Panoche Hills in central California, an area formerly used by motorcycles together with an adjacent unused area were monitored from 1971 to 1975. Observations in both areas included measurements of precipitation, runoff, soil moisture, soil bulk density, plant cover, and erosion surveys. At Dove Spring Canyon in southern California erosion was measured on a site that is currently being used for motorcycle hill-climbing. At the Panoche Hills site, the area used by motorcycles produced about eight times as much runoff as the unused area. Similarly, sediment yield from the used areas was 857 cubic meters/sq km, while the quantity of sediment from the unused area was not measurable by standard methods. At the Dove Spring Canyon site, which is still being used for hill-climbing, erosion surveys show that degradation in trails has been as much as 0.3 m in the period 1973-75. Compaction of soils and reduction of permeability appears to be the most serious hydrologic impact of motorcycle use at Panoche Hills. Increased bulk density of soils reduces depth of moisture penetration which deprives plants of moisture needed for growth. (Woodard-USGS)

California↗
USGS2014

Correlation of gene expression and contaminat concentrations in wild largescale suckers: a field-based study

Toxic compounds such as organochlorine pesticides (OCs), polychlorinated biphenyls (PCBs), and polybrominated diphenyl ether flame retardants (PBDEs) have been detected in fish, birds, and aquatic mammals that live in the Columbia River or use food resources from within the river. We developed a custom microarray for largescale suckers (Catostomus macrocheilus) and used it to investigate the molecular effects of contaminant exposure on wild fish in the Columbia River. Using Significance Analysis of Microarrays (SAM) we identified 72 probes representing 69 unique genes with expression patterns that correlated with hepatic tissue levels of OCs, PCBs, or PBDEs. These genes were involved in many biological processes previously shown to respond to contaminant exposure, including drug and lipid metabolism, apoptosis, cellular transport, oxidative stress, and cellular chaperone function. The relation between gene expression and contaminant concentration suggests that these genes may respond to environmental contaminant exposure and are promising candidates for further field and laboratory studies to develop biomarkers for monitoring exposure of wild fish to contaminant mixtures found in the Columbia River Basin. The array developed in this study could also be a useful tool for studies involving endangered sucker species and other sucker species used in contaminant research.

Oregon;Washington↗
USGS2019

Use of high-throughput screening results to prioritize chemicals for potential adverse biological effects within a West Virginia Watershed

Organic chemicals from industrial, agricultural, and residential activities can enter surface waters through regulated and unregulated discharges, combined sewer overflows, stormwater runoff, accidental spills, and leaking septic-conveyance systems on a daily basis. The impact of point and nonpoint contaminant sources can result in adverse biological effects for organisms living in or near surface waters. Assessing the adverse or toxic effects that may result when exposure occurs is complicated by the fact that many commonly used chemicals lack toxicity information or water quality standards. To address these challenges, an exposure-activity ratio (EAR) screening approach was used to prioritize environmental chemistry data in a West Virginia watershed (Wolf Creek). Wolf Creek is a drinking water source and recreation resource with documented water quality impacts from point and nonpoint sources. The EAR screening approach uses high-throughput screening (HTS) data from ToxCast as a method of integrating environmental chemical occurrence and biological effects data. Using water quality schedule 4433, which targets 69 organic waste compounds typically found in domestic and industrial wastewater, chemicals were screened for potential adverse biological affects at multiple sites in the Wolf Creek watershed. Cumulative EAR mixture values were greatest at Sites 2 and 3, where bisphenol A (BPA) and pentachlorophenol exhibited maximum EAR values of 0.05 and 0.002, respectively. Site 2 is downstream of an unconventional oil and gas (UOG) wastewater disposal facility with documented water quality impacts. Low-level organic contaminants were found at all sample sites in Wolf Creek, except Site 10, where Wolf Creek enters the New River. The application of an EAR screening approach allowed our study to extend beyond traditional environmental monitoring methods to identify multiple sites and chemicals that warrant further investigation.

West Virginia↗
USGS1983

A summary of ground-water pumpage in the Central Valley, California, 1961-77

In the Central Valley of California, a great agricultural economy has been developed in a semiarid environment. This economy is supported by imported surface water and 9 to 15 million acre-feet per year of ground water. Estimates of ground-water pumpage computed from power consumption have been compiled and summarized. Under ideal conditions, the accuracy of the methods used is about 3 percent. This level of accuracy is not sustained over the entire study area. When pumpage for the entire area is mapped, the estimates seem to be consistent areally and through time. A multiple linear-regression model was used to synthesize data for the years 1961 through 1977, when power data were not available. The model used a relation between ground-water pumpage and climatic indexes to develop a full suite of pumpage data to be used as input to a digital ground-water model, one of the products of the Central Valley Aquifer Project. Statistical analysis of well-perforation data from drillers ' logs and water-temperature data was used to determine the percentage of pumpage that was withdrawn from each of two horizontal layers. (USGS)

Water-Resources Investigations Report↗
USGS1999

Estimates of ground-water discharge as determined from measurements of evapotranspiration, Ash Meadows area, Nye County, Nevada

Ash Meadows is one of the major discharge areas within the regional Death Valley ground-water flow system of southern Nevada and adjacent California. Ground water discharging at Ash Meadows is replenished from inflow derived from an extensive recharge area that includes the eastern part of the Nevada Test Site (NTS). Currently, contaminants introduced into the subsurface by past nuclear testing at NTS are the subject of study by the U.S. Department of Energy's Environmental Restoration Program. The transport of any contaminant in contact with ground water is controlled in part by the rate and direction of ground-water flow, which itself depends on the location and quantity of ground water discharging from the flow system. To best evaluate any potential risk associated with these test-generated contaminants, studies were undertaken to accurately quantify discharge from areas downgradient from the NTS. This report presents results of a study to refine the estimate of ground-water discharge at Ash Meadows. The study estimates ground-water discharge from the Ash Meadows area through a rigorous quantification of evapotranspiration (ET). To accomplish this objective, the study identifies areas of ongoing ground-water ET, delineates unique areas of ET defined on the basis of similarities in vegetation and soil-moisture conditions, and computes ET rates for each of the delineated areas. A classification technique using spectral-reflectance characteristics determined from satellite images recorded in 1992 identified seven unique units representing areas of ground-water ET. The total area classified encompasses about 10,350 acres dominated primarily by lush desert vegetation. Each unique area, referred to as an ET unit, generally consists of one or more assemblages of local phreatophytes. The ET units identified range from sparse grasslands to open water. Annual ET rates are computed by energy-budget methods from micrometeorological measurements made at 10 sites within six of the seven identified ET units. Micrometeorological data were collected for a minimum of 1 year at each site during 1994 through 1997. Evapotranspiration ranged from 0.6 foot per year in a sparse, dry saltgrass environment to 8.6 feet per year over open water. Ancillary data, including water levels, were collected during this same period to gain additional insight into the evapotranspiration process. Water levels measured in shallow wells showed annual declines of more than 10 feet and daily declines as high as 0.3 foot attributed to water losses associated with evapotranspiration. Mean annual ET from the Ash Meadows area is estimated at 21,000 acre-feet. An estimate of ground-water discharge, based on this ET estimate, is presented as a range to account for uncertainties in the contribution of local precipitation. The estimates given for mean annual ground-water discharge range from 18,000 to 21,000 acre-feet. The low estimate assumes a large contribution from local precipitation in computed ET rates; whereas, the high estimate assumes no contribution from local precipitation. The range presented is only slightly higher than previous estimates of ground-water discharge from the Ash Meadows area based primarily on springflow measurements.

Nevada↗
USGS2024

Accounting for missing ticks: Use (or lack thereof) of hierarchical models in tick ecology studies

Ixodid (hard) ticks play important ecosystem roles and have significant impacts on animal and human health via tick-borne diseases and physiological stress from parasitism. Tick occurrence, abundance, activity, and key life-history traits are highly influenced by host availability, weather, microclimate, and landscape features. As such, changes in the environment can have profound impacts on ticks, their hosts, and the spread of diseases. Researchers recognize that spatial and temporal factors influence activity and abundance and attempt to account for both by conducting replicate sampling bouts spread over the tick questing period. However, common field methods notoriously underestimate abundance, and it is unclear how (or if) tick studies model the confounding effects of factors influencing activity and abundance. This step is critical as unaccounted variance in detection can lead to biased estimates of occurrence and abundance. We performed a descriptive review to evaluate the extent to which studies account for the detection process while modeling tick data. We also categorized the types of analyses that are commonly used to model tick data. We used hierarchical models (HMs) that account for imperfect detection to analyze simulated and empirical tick data, demonstrating that inference is muddled when detection probability is not accounted for in the modeling process. Our review indicates that only 5 of 412 (1 %) papers explicitly accounted for imperfect detection while modeling ticks. By comparing HMs with the most common approaches used for modeling tick data (e.g., ANOVA), we show that population estimates are biased low for simulated and empirical data when using non-HMs, and that confounding occurs due to not explicitly modeling factors that influenced both detection and abundance. Our review and analysis of simulated and empirical data shows that it is important to account for our ability to detect ticks using field methods with imperfect detection. Not doing so leads to biased estimates of occurrence and abundance which could complicate our understanding of parasite-host relationships and the spread of tick-borne diseases. We highlight the resources available for learning HM approaches and applying them to analyzing tick data.

Maine↗
USGS2000

Characterizing Manatee habitat use and seagrass grazing in Florida and Puerto Rico: Implications for conservation and management

The Indian River Lagoon on the Atlantic coast of Florida, USA, and the east coast of Puerto Rico provide contrasting environments in which the endangered West Indian Manatee Trichechus manatus experiences different thermal regimes and seagrass communities. We compare Manatee feeding behaviour in these two regions, examine the ecological effects of Manatee grazing on a seagrass community in the Indian River Lagoon, describe the utility of aerial surveys, radio tracking, and seagrass mapping to study Manatee feeding patterns, and develop hypotheses on sirenian feeding strategies in temperate and tropical seagrass communities. In both the Indian River Lagoon and Puerto Rico, Manatees were typically observed grazing in water depths = 2.0 m and more frequently on the most abundant seagrasses present in the community: Halodule wrightii in the Indian River Lagoon and Thalassia testudinum in eastern Puerto Rico. Where both H. wrightii and Syringodium filiforme were consumed in the Indian River Lagoon, Manatees tended to remove more S. filiforme than H. wrightii rhizome + root biomass. Even though 80 to 95% of the short-shoot biomass and 50 to 67% of the rhizome + root biomass were removed, grazed patches of H. wrightii and S. filiforme recovered significantly between February and August. H. wrightii may be both more resistant and resilient than S. filiforme to the impacts of Manatee grazing. Despite the significantly greater abundance of T. testudinum in Puerto Rico, Manatees exhibited selective feeding by returning to specific sites with abundant H. wrightii. They also appeared to feed selectively on T. testudinum shoots associated with clumps of the calcareous alga Halimeda opuntia. We hypothesize that Florida Manatees are less specialized seagrass grazers than Manatees in tropical regions like Puerto Rico. Continued research on Manatee grazing ecology in temperate to tropical seagrass communities will enable better protection and management of these vital and unique marine resources.

Florida↗
USGS2018

Coastal effects

The Coasts chapter of the Third National Climate Assessment, published in 2014, focused on coastal lifelines at risk, economic disruption, uneven social vulnerability, and vulnerable ecosystems. This Coastal Effects chapter of the Fourth National Climate Assessment updates those themes, with a focus on integrating the socioeconomic and environmental impacts and consequences of a changing climate. Specifically, the chapter builds on the threat of rising sea levels exacerbating tidal and storm surge flooding, the state of coastal ecosystems, and the treatment of social vulnerability by introducing the implications for social equity. U.S. coasts are dynamic environments and economically vibrant places to live and work. As of 2013, coastal shoreline counties were home to 133.2 million people, or 42% of the population. The coasts are economic engines that support jobs in defense, fishing, transportation, and tourism industries; contribute substantially to the U.S. gross domestic product; and serve as hubs of commerce, with seaports connecting the country with global trading partners. Coasts are home to diverse ecosystems such as beaches, intertidal zones, reefs, seagrasses, salt marshes, estuaries, and deltas that support a range of important services including fisheries, recreation, and coastal storm protection. U.S. coasts span three oceans, as well as the Gulf of Mexico, the Great Lakes, and Pacific and Caribbean islands. The social, economic, and environmental systems along the coasts are being affected by climate change. Threats from sea level rise (SLR) are exacerbated by dynamic processes such as high tide and storm surge flooding (Ch. 19: Southeast, KM 2) , erosion (Ch. 26: Alaska, KM 2) , waves and their effects, saltwater intrusion into coastal aquifers and elevated groundwater tables (Ch. 27: Hawaiʻi & Pacific Islands, KM 1; Ch. 3: Water, KM 1) , local rainfall (Ch. 3: Water, KM 1) , river runoff (Ch. 3: Water, KM 1) , increasing water and surface air temperatures (Ch. 9: Oceans, KM 3) , and ocean acidification (see Ch. 2: Climate, KM 3 and Ch. 9: Oceans, KM 1, 2, and 3 for more information on ocean acidification, hypoxia, and ocean warming) . Although storms, floods, and erosion have always been hazards, in combination with rising sea levels they now threaten approximately $1 trillion in national wealth held in coastal real estate and the continued viability of coastal communities that depend on coastal water, land, and other resources for economic health and cultural integrity (Ch. 15: Tribes, KM 1 and 2) .

Report↗
USGS2009

Synthesis of ground and remote sensing data for monitoring ecosystem functions in the Colorado River Delta, Mexico

The delta of the Colorado River in Mexico supports a rich mix of estuarine, wetland and riparian ecosystems that provide habitat for over 350 species of birds as well as fish, marine mammals, and other wildlife. An important part of the delta ecosystem is the riparian corridor, which is supported by agricultural return flows and waste spills of water originating in the U.S. and Mexico. These flows may be curtailed in the future due to climate change and changing land use practices (out-of-basin water transfers, increased agricultural efficiency, and more optimal management of dams) in the U.S. and Mexico, and resource managers need to monitor the effects of their water management practices on these ecosystems. We developed ground-validated, remote sensing methods to monitor the vegetation status, habitat value, and water use of wetland and riparian ecosystems using multi-temporal, multi-resolution images. The integrated methodology allowed us to project species composition, leaf area index, fractional cover, habitat value, and evapotranspiration over seasons and years throughout the delta, in response to variable water flows from the U.S. to Mexico. Waste spills of water from the U.S. have regenerated native cottonwood and willow trees in the riparian corridor and created backwater and marsh areas that support birds and other wildlife. However, the main source of water supporting the riparian vegetation is the regional aquifer recharged by underflow from U.S. and Mexico irrigation districts. Native trees have a short half-life in the riparian zone due to human-set fires and harvesting for timber. Active management, monitoring, and restoration programs are needed to maintain the habitat value of this ecosystem for the future.

Colorado River Delta↗
USGS2017

Movements of four native Hawaiian birds across a naturally fragmented landscape

Animals often increase their fitness by moving across space in response to temporal variation in habitat quality and resource availability, and as a result of intra and inter-specific interactions. The long-term persistence of populations and even whole species depends on the collective patterns of individual movements, yet animal movements have been poorly studied at the landscape level. We quantified movement behavior within four native species of Hawaiian forest birds in a complex lava-fragmented landscape: Hawai‛i ‘amakihi Chlorodrepanis virens , ‘oma‘o Myadestes obscurus , ‘apapane Himatione sanguinea , and ‘i‘iwi Drepanis coccinea . We evaluated the relative importance of six potential intrinsic and extrinsic drivers of movement behavior and patch fidelity: 1) forest fragment size, 2) the presence or absence of invasive rats ( Rattus sp.), 3) season, 4) species, 5) age, and 6) sex. The study was conducted across a landscape of 34 forest fragments varying in size from 0.07 to 12.37 ha, of which 16 had rats removed using a treatment-control design. We found the largest movements in the nectivorous ‘apapane and ‘i‘iwi, intermediate levels in the generalist Hawai‛i ‘amakihi, and shortest average movement for the ‘oma‘o, a frugivore. We found evidence for larger patch sizes increasing patch fidelity only in the ‘oma‘o, and an effect of rat-removal increasing patch fidelity of Hawai‛i ‘amakihi only after two years of rat-removal. Greater movement during the non-breeding season was observed in all species, and season was an important factor in explaining higher patch fidelity in the breeding season for ‘apapane and ‘i‘iwi. Sex was important in explaining patch fidelity in ‘oma‘o only, with males showing higher patch fidelity. Our results provide new insights into how these native Hawaiian species will respond to a changing environment, including habitat fragmentation and changing distribution of threats from climate change.

Journal of Avian Biology↗
USGS2015

Ground-truthing electrical resistivity methods in support of submarine groundwater discharge studies: Examples from Hawaii, Washington, and California

Submarine groundwater discharge (SGD) is an important conduit that links terrestrial and marine environments. SGD conveys both water and water-borne constituents into coastal waters, where these inflows may impact near-shore ecosystem health and sustainability. Multichannel electrical resistivity techniques have proven to be a powerful tool to examine scales and dynamics of SGD and SGD forcings. However, there are uncertainties both in data aquisition and data processing that must be addressed to maximize the effectiveness of this tool in estuarine or marine environments. These issues most often relate to discerning subtle nuances in the flow of electricity through variably saturated media that can also be highly conductive ( i.e., seawater). Three contrasting field sites were examined for this study to assess the effectiveness of electrical resistivity techniques in varying coastal settings by comparing resistivity data to direct salinity and resistivity observations, quantifying changes in lithology and beach geomorphology, and fine-tuning inversion protocols. The three study sites all have substantial (up to 85 cm day −1 ) submarine groundwater discharge rates, but the hydrologic, oceanographic, and geologic characteristics of the sites are all very different. At a site in Pelekane Bay on the Big Island of Hawaii, seasonal flooding introduces very high concentrations of fine to coarse sediment into the bay. Near-shore circulation is limited in Pelekane Bay, so this newly introduced sediment can become deposited in the bay where it accumulates over time. At a site in Hood Canal, a fjord within Puget Sound, Washington, SGD rates can be high because of the large tidal range, abundant recharge, and steep hydrologic gradients. At Younger Lagoon in northern California, the flow of groundwater towards the coast is much more parsimonious, but here marine processes, including recirculated seawater, are important in controlling the flow of material towards the coast. Rigorous ground-truthing at each field site showed that multi-channel electrcial resistivity techniques can reproduce the scales and dynamics of a seepage field when such data are correctly collected, and when the model inversions are tuned to field site characteristics. Such information can provide a unique perspective on the scales and dynamics of exchange processes within a coastal aquifer—information essential to scientists and resource managers alike.

California, Hawaii, Washington↗
USGS2008

Improvements in the use of aquatic herbicides and establishment of future research directions

Peer-reviewed literature over the past 20 years identifies significant changes and improvements in chemical control strategies used to manage nuisance submersed vegetation. The invasive exotic plants hydrilla (Hydrilla verticillata L.f. Royle) and Eurasian watermilfoil (Myriophyllum spicatum L.) continue to spread and remain the plant species of greatest concern for aquatic resource managers at the national scale. Emerging exotic weeds of regional concern such as egeria (Egeria densa Planch.), curlyleaf pondweed (Potamogeton crispus L.), and hygrophila (Hygrophila polysperma (Roxb.) T. Anders), as well as native plants such as variable watermilfoil (Myriophyllum heterophyllum Michx), and cabomba (Cabomba caroliniana Gray) are invasive outside their home ranges. In addition, there is always the threat of new plant introductions such as African elodea (Lagarosiphon major (Ridley) Moss) or narrow-leaf anacharis (Egeria najas Planchon). The registration of the bleaching herbicide fluridone in the mid 1980s for whole-lake and large-scale management stimulated numerous lines of research involving reduction of use rates, plant selectivity, residue monitoring, and impacts on fisheries. In addition to numerous advances, the specificity of fluridone for a single plant enzyme led to the first documented case of herbicide resistance in aquatic plant management. The resistance of hydrilla to fluridone has stimulated a renewed interest by industry and others in the registration of alternative modes of action for aquatic use. These newer chemistries tend to be enzyme-specific compounds with favorable non-target toxicity profiles. Registration efforts have been facilitated by increased cooperation between key federal government agencies that have aquatic weed control and research responsibilities, and regulators within the U.S. Environmental Protection Agency (USEPA). We reviewed past and current research efforts to identify areas in need of further investigation and to establish priorities for future research directions in chemical management of submersed plants. The priorities we identified include: (A) improving methods for evaluating non-target impacts of herbicides with an emphasis on threatened and endangered species, or species of special concern; (B) improving herbicide performance in flowing-water environments, including irrigation canals; (C) screening and developing new herbicides to supplement fluridone for large-scale or whole-lake management approaches; (D) screening and developing new organic algaecides to supplement the use of copper-based compounds; (E) developing risk assessment tools to educate the public on the risks of invasive species and chemical management options; (F) increasing cooperative research with ecologists and fisheries scientists to evaluate the long-term impacts of invasive species introductions and herbicide programs on native plant assemblages, water quality, and fish populations; and (G) improving the integration of chemical control technology with other aquatic plant management disciplines. While circumstances may dictate setting new priorities or dropping current ones, the list we have generated represents our vision of the needs that will require the greatest focus over the next several years.

Conference Paper↗
USGS2018

Contaminants in tropical island streams and their biota

Environmental contamination is problematic for tropical islands due to their typically dense human populations and competing land and water uses. The Caribbean island of Puerto Rico (USA) has a long history of anthropogenic chemical use, and its human population density is among the highest globally, providing a model environment to study contaminant impacts on tropical island stream ecosystems. Polycyclic Aromatic Hydrocarbons, historic-use chlorinated pesticides, current-use pesticides, Polychlorinated Biphenyls (PCBs), and metals (mercury, cadmium, copper, lead, nickel, zinc, and selenium) were quantified in the habitat and biota of Puerto Rico streams and assessed in relation to land-use patterns and toxicological thresholds. Water, sediment, and native fish and shrimp species were sampled in 13 rivers spanning broad watershed land-use characteristics during 2009–2010. Contrary to expectations, freshwater stream ecosystems in Puerto Rico were not severely polluted, likely due to frequent flushing flows and reduced deposition associated with recurring flood events. Notable exceptions of contamination were nickel in sediment within three agricultural watersheds (range 123–336 ppm dry weight) and organic contaminants (PCBs, organochlorine pesticides) and mercury in urban landscapes. At an urban site, PCBs i n several fish species (Mountain Mullet Agonostomus monticola [range 0.019–0.030 ppm wet weight] and American Eel Anguilla rostrata [0.019–0.031 ppm wet weight]) may pose human health hazards, with concentrations exceeding the U.S. Environmental Protection Agency (EPA) consumption limit for 1 meal/month. American Eel at the urban site also contained dieldrin (range < detection-0.024 ppm wet weight) that exceeded the EPA maximum allowable consumption limit. The Bigmouth Sleeper Gobiomorous dormitor , an important piscivorus sport fish, accumulated low levels of organic contaminants in edible muscle tissue (due to its low lipid c ontent) and may be most suitable for human consumption island-wide; only mercury at one site (an urban location) exceeded EPA's consumption limit of 3 meals/month for this species. These results comprise the first comprehensive island-wide contaminant assessment of Puerto Rico streams and biota and provide natural resource and public health agencies here and in similar tropical islands elsewhere with information needed to guide ecosystem and fisheries conservation and management and human health risk assessment.

Environmental Research↗
USGS2002

Impacts of swine manure pits on groundwater quality

Manure deep-pits are commonly used to store manure at confined animal feeding operations. However, previous to this study little information had been collected on the impacts of deep-pits on groundwater quality to provide science-based guidance in formulating regulations and waste management strategies that address risks to human health and the environment. Groundwater quality has been monitored since January 1999 at two hog finishing facilities in Illinois that use deep-pit systems for manure storage. Groundwater samples were collected on a monthly basis and analyzed for inorganic and bacteriological constituent concentrations. The two sites are located in areas with geologic environments representing different vulnerabilities for local groundwater contamination. One site is underlain by more than 6 m of clayey silt, and 7-36 m of shale. Concentrations of chloride, ammonium, phosphate, and potassium indicated that local groundwater quality had not been significantly impacted by pit leakage from this facility. Nitrate concentrations were elevated near the pit, often exceeding the 10 mg N/l drinking water standard. Isotopic nitrate signatures suggested that the nitrate was likely derived from soil organic matter and fertilizer applied to adjacent crop fields. At the other site, sandstone is located 4.6-6.1 m below land surface. Chloride concentrations and ??15N and ??18O values of dissolved nitrate indicated that this facility may have limited and localized impacts on groundwater. Other constituents, including ammonia, potassium, phosphate, and sodium were generally at or less than background concentrations. Trace- and heavy-metal concentrations in groundwater samples collected from both facilities were at concentrations less than drinking water standards. The concentration of inorganic constituents in the groundwater would not likely impact human health. Fecal streptococcus bacteria were detected at least once in groundwater from all monitoring wells at both sites. Fecal streptococcus was more common and at greater concentrations than fecal coliform. The microbiological data suggest that filtration of bacteria by soils may not be as effective as commonly assumed. The presence of fecal bacteria in the shallow groundwater may pose a significant threat to human health if the ground water is used for drinking. Both facilities are less than 4 years old and the short-term impacts of these manure storage facilities on groundwater quality have been limited. Continued monitoring of these facilities will determine if they have a long-term impact on groundwater resources. ?? 2002 Elsevier Science Ltd. All rights reserved.

Environmental Pollution↗
USGS2022

Over a third of groundwater in USA public-supply aquifers is Anthropocene-age and susceptible to surface contamination

The distribution of groundwater age is useful for evaluating the susceptibility and sustainability of groundwater resources. Here, we compute the aquifer-scale cumulative distribution function to characterize the age distribution for 21 Principal Aquifers that account for ~80% of public-supply pumping in the United States. The aquifer-scale cumulative distribution function for each Principal Aquifer was derived from an ensemble of modeled age distributions (~60 samples per aquifer) based on multiple tracers: tritium, tritiogenic helium-3, sulfur hexafluoride, chlorofluorocarbons, carbon-14, and radiogenic helium-4. Nationally, the groundwater is 38% Anthropocene (since 1953), 34% Holocene (75 – 11,800 years ago), and 28% Pleistocene (>11,800 years ago). The Anthropocene fraction ranges from <5 to 100%, indicating a wide range in susceptibility to land-surface contamination. The Pleistocene fraction of groundwater exceeds 50% in 7 eastern aquifers that are predominately confined. The Holocene fraction of groundwater exceeds 50% in 5 western aquifers that are predominately unconfined. The sustainability of pumping from these Principal Aquifers depends on rates of recharge and release of groundwater stored in fine-grained layers.

Nature Communications Earth & Environment↗
USGS2020

Mortality and cholinesterase inhibition in butterflies following aerial naled applications for mosquito control on the National Key Deer Refuge

Natural resource managers are concerned about the impacts of aerial ultra-low volume spray (ULV) of insecticides for mosquito control (i.e., mosquito adulticides) and seek science-driven management recommendations that reduce risk but allow vector control for nearby human populations. Managers at the National Key Deer Refuge (Florida Keys, FL) are concerned for ULV effects upon conservation efforts for imperiled butterflies (Florida leafwing [ Anaea troglodyta floridalis ] and Bartram’s hairstreak [ Strymon acis bartrami ] butterflies). No-spray zones were designated for protection of those butterflies, but their effectiveness for mitigation is unclear. To address this uncertainty, cholinesterase activity (ChE) and mortality were monitored for caged butterflies gulf fritillary [ Agraulis vanilla ] and great southern white [ Ascia monuste ]) deployed on the Refuge during three aerial ULV applications of the insecticide naled. Residue samplers also were deployed to estimate butterfly exposure. Spray efficacy against mosquitoes was assessed by deploying caged mosquitoes at the same locations as the butterflies. Average naled residue levels on filter paper samplers in the target area (1882–2898 µg/m 2 ) was significantly greater than in the no-spray zone (9–1562 µg/m 2 ). Differences between the no-spray zone and target area for butterfly mortality and ChE were inconsistent. Average mortality was significantly lower, and average ChE was significantly higher in the no-spray zone for larvae of one species but not for larvae of the other species. Mosquito mortality did not differ significantly between the two areas. Data from the present study reflect the inconsistent effectiveness of no-spray zones on the Refuge using standard methods employed at the time by the vector control agency in the Florida Keys and possibly by other vector control agencies in similar coastal environments. Furthermore, these findings helped to guide the design and to improve the conservation value of future no-spray zone delineations while allowing for treatment in areas where mosquito control is necessary for vector-borne disease reduction.

Florida↗
USGS2014

Fathead minnow and bluegill sunfish life-stage responses to 17β-estradiol exposure in outdoor mesocosms

Developmental and reproductive effects of 17β-estradiol (E2) exposure on two generations of fathead minnows and one generation of bluegill sunfish were assessed. Fish were exposed to E2 for six continuous weeks in outdoor mesocosms simulating natural lake environments. First generation fish were exposed while sexually mature. Second generation fathead minnows were exposed either during early development, sexual maturity, or both stages. Multiple endpoints were measured to assess effects of E2 exposure on fecundity and fish health and development. Plasma vitellogenin concentrations were highly variable in all fish. Differences in egg production timing for both species indicate differences in fecundity between females exposed to E2 and controls. First generation fathead minnows exposed to E2 had lower body condition factors and reduced secondary sexual characteristic expression by males. Only a difference in relative liver weight was observed in second generation fathead minnows. First generation bluegill males exposed to E2 had significantly smaller testes compared to controls. Although fish response was highly variable, results indicate that exposure to E2 at environmentally relevant concentrations affect fathead minnow and bluegill sunfish health and development, which may have implications for the health and sustainability of fish populations. Furthermore, exposure timing and environmental factors affect fish response to E2 exposure.

Journal of the American Water Resources Associatio↗
USGS1996

Summary of biological and contaminant investigations related to stream water quality and environmental setting in the Upper Colorado River basin, 1938-95

As part of the U.S. Geological Survey's National Water-Quality Assessment (NAWQA) program, an inventory of the biological and contaminant investigations for the Upper Colorado River Basin study unit was conducted. To enhance the sampling design for the biological component of the program, previous studies about the ecology of aquatic organisms and contaminants were compiled from computerized literature searches of biological data bases and by contacting other Federal, State, and local agencies. Biological and contaminant investigations that have been conducted throughout the basin since 1938 were categorized according to four general categories of biological investigations and two categories of contaminant investigations: algal communities, macroinvertebrate communities, fish communities, habitat characterization, contaminants in organism tissue, and contaminants in bed sediment. The studies were identified by their locations in two physiographic provinces, the Southern Rocky Mountains and the Colorado Plateau, and by the predominant land use in the area of the investigation. Studies on algal communities and contaminants in organism tissue and in bed sediment are limited throughout the basin. Studies on macroinvertebrate and fish communities and habitat characterization are the most abundant in the study unit. Natural and human factors can affect biological communities and their composition. Natural factors that affect background water-quality conditions are physiography, climate, geology, and soils. Algae, macroinvertebrates, and fish that are present in the Southern Rocky Mountains and the Colorado Plateau physiographic provinces vary with altitude and physical environment. Green algae and diatoms are predominant in the higher altitude streams, and blue-green, golden-brown, and green algae are predominant in the lower altitude streams. Caddisflies, mayflies, and stoneflies are the dominant macroinvertebrates in the higher altitudes, whereas aquatic worms, leeches, and dragonflies are more common at lower altitudes. Cold-water species, such as trout, are present at the higher altitudes, and warmer water species, such as catfish, carp, and suckers, are predominant at the lower altitudes. Human factors that affect water-quality conditions are mining, urbanization, agriculture, and hydrologic modifications. Mining areas can be depleted of organisms or contain a low diversity of species. Acid-tolerant algae, such as certain species of green algae and diatoms, and metal-tolerant caddisflies can be present in mining areas. Urbanized areas are located in the Southern Rocky Mountains and in the Colorado Plateau and contain species characteristic of the physiographic provinces. Agricultural areas contain species, such as blue-green algae, aquatic worms, suckers, and carp, that can tolerate organic enrichment, sedimentation, and lower concentrations of dissolved oxygen.

Water-Resources Investigations Report↗