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At least 757 records · Page 42Linked to original sources
USGS2023

Alternative lifestyles: A plague persistence hypothesis

Several explanations have been posited for how the plague bacterium ( Yersinia pestis ) reemerges during sylvatic cycles within the same foci over many years, and often without direct evidence of host die-offs. One prevalent view is that transmission-optimized Y. pestis bacteria, exhibiting epizootic/enzootic behavior, almost continually replicate and survive through repeated, linked, host-centered propagation events. These bacteria, we will refer to as “ r-pestis ” type ecotype(s), represent a limited number of phenotypic lineages exhibiting optimal transmissibility and high rates of reproduction. These attributes, it is thought, assure their durability through time. For continuous r-pestis type expansions to be successful, adequate numbers of fleas and hosts must become infected to produce massive numbers of bacteria. In the process, host and flea numbers decline as they succumb to plague. Here we hypothesize that r-pestis population expansions seed the environment and confront a unique, highly competitive local milieu, where natural selection favors new ecotypes that incorporate a range of emergent adaptive survival strategies. These newly adapted survivors we recognize as a range of “ K - pestis ” ecotypes with greater durability and lower reproduction rates. These emergent K - pestis forms may arise in succession or coexist for varying periods of time with r-pestis ecotypes, and with other K - pestis ecotypes. Among K-pestis ecotypes, we hypothesize that through adaptive radiations, some persist within flea life stages, soil, organic waste, amoebae, plants, carcasses, hosts, or within niches yet to be characterized. In some settings, after a long quiet period, when favorable, K-pestis bacteria may trigger a singular event where an r-pestis transmission stream emerges precipitating another enzootic/epizootic progression. If this hypothesis withstands rigorous testing, then Y. pestis might represent an even more formidable, enduring, and adaptable foe, where unforeseen local events could trigger new epidemic and epizootic/enzootic events threatening humans and populations of other mammals, including those of conservation concern.

Ecosphere↗
USGS2024

Sensitivity of Alabama freshwater gastropod species to nickel exposure

Snails are effective bioindicators due to their prolific distribution, high level of endemism, and capacity to accumulate contaminants. Freshwater snails have unique ecological niches which are imperiled by land‐use change and the introduction of hazardous chemicals. To assess how environmental alterations affect gastropods, lab‐based studies are needed to characterize the toxicity of specific stressors. This can help guide policy decisions and remediation efforts. The aim of this research was to characterize acute toxicity of nickel (Ni) on endemic snails ( Somatogyrus georgianus [Walker, 1904], Elimia cahawbensis [Lea, 1861], and Elimia spp.) and measure the accumulation of Ni and mineral elements including calcium (Ca), magnesium, potassium, and sodium (Na). Snails were exposed to six concentrations (25–800 µg/L) of Ni for 96 h. Among the studied snail species, E. cahawbensis was the most sensitive to Ni, with the lowest lethal concentration where 50% of the organisms died (LC50) at 88.88 µg/L Ni after 96 h. The LC50 at 96 h for S. georgianus was 167.78 µg/L Ni, and 393.13 μg/L Ni for Elimia spp. Except for Elimia spp., mortality of the other two snail species corresponded to the whole‐body uptake of Ni. Nickel exposure also influenced Ca and Na uptake for Elimia spp. All three endemic species are potential candidate species for evaluating localized effects of human activities, and the present study provides a first step in characterizing how snails would be affected by environmental alterations. More research could further characterize potential effects of other human stressors on these endemic snail species. Future research into subindividual responses and routes of exposure can further elucidate variations in species sensitivity.

Alabama↗
USGS1993

The Loma Prieta, California, earthquake of October 17, 1989 - Public response: Chapter B in The Loma Prieta, California, earthquake of October 17, 1989: Societal Response (Professional Paper 1553)

Major earthquakes provide seismologists and engineers an opportunity to examine the performance of the Earth and the man-made structures in response to the forces of the quake. So, too, do they provide social scientists an opportunity to delve into human responses evoked by the ground shaking and its physical consequences. The findings from such research can serve to guide the development and application of programs and practices designed to reduce death, injury, property losses, and social disruption in subsequent earthquakes. This chapter contains findings from studies focused mainly on public response to the Loma Prieta earthquake; that is, on the behavior and perceptions of the general population rather than on the activities of specific organizations or on the impact on procedures or policies. A major feature of several of these studies is that the information was collected from the population throughout the Bay area, not just from persons in the most badly damaged communities or who had suffered the greatest losses. This wide range serves to provide comparisons of behavior for those most directly affected by the earthquake with others who were less directly affected by it but still had to consider it very “close to home.”

California↗
USGS2012

Water quality and mass transport in four watersheds in eastern Puerto Rico: Chapter E in Water quality and landscape processes of four watersheds in eastern Puerto Rico

Water quality of four small watersheds in eastern Puerto Rico has been monitored since 1991 as part of the U.S. Geological Survey's Water, Energy, and Biogeochemical Budgets program. These watersheds represent a montane, humid-tropical environment and differ in geology and land cover. Two watersheds are located on granitic rocks, and two are located on volcaniclastic rock. For each bedrock type, one watershed is covered with mature rainforest in the Luquillo Mountains, and the other watershed is undergoing reforestation after being affected by agricultural practices typical of eastern Puerto Rico. A subwatershed of the Icacos watershed, the Guabá, was also monitored to examine scaling effects. The water quality of the rivers draining forest, in the Icacos and Guabá (granitic watersheds) and Mameyes (a volcaniclastic watershed), show little contamination by human activities. The water is well oxygenated and has a nearly neutral pH, and nutrient concentrations are low. Concentrations of nutrients in the disturbed watersheds, the Cayaguás (granitic rock) and Canóvanas (volcaniclastic rock), are greater than in the forested watersheds, indicating some inputs from human activities. High in-stream productivity in the Canóvanas watershed leads to occasional oxygen and calcite supersaturation and carbon dioxide undersaturation. Suspended sediment concentrations in all watersheds are low, except during major storms. Most dissolved constituents derived from bedrock weathering or atmospheric deposition (including sodium, magnesium, calcium, silica, alkalinity, and chloride) decrease in concentration with increasing runoff, reflecting dilution from increased proportions of overland or near-surface flow. Strongly bioactive constituents (dissolved organic carbon, potassium, nitrate, ammonium ion, and phosphate) commonly display increasing concentration with increasing runoff, regardless of their ultimate origin (bedrock or atmosphere). The concentrations of many of the bioactive constituents eventually decrease at runoff rates greater than 3 to 10 millimeters per hour, presumably reflecting an increased relative contribution from overland flow. Sulfate behaves like the nonbioactive constituents in the Canóvanas, Cayaguás, and Mameyes watersheds but like a bioactive constituent in the Icacos and Guabá watersheds. Storms resulted in several anomalous sample compositions. Runoff waters from a number of storms - mostly hurricanes, but also other storms - have exceptionally high chloride concentrations, presumably resulting from windborne seasalt from the ocean, and low nitrate concentrations, reflecting a dominance of maritime air masses contributing moisture to the storms. High-potassium samples, without high chloride, are also associated with some smaller storms that followed Hurricane Georges in 1998; they are likely related to the breakdown of fallen vegetation. Finally, occasional low-silica events are observed in the Icacos and Guabá watersheds in the years prior to Hurricane Georges, but not after; this difference may be related to a change in hydrologic flow paths.

Professional Paper↗
USGS2024

A new method for bioassessment of ecosystems with complex communities and environmental gradients

Bioassessment of complex and heterogeneous ecosystems is a challenge when there are multiple, strong, natural environmental gradients; unknown, or spatially varying, mixtures of stressors; and large numbers of taxa with unknown responses to both the environmental gradients and the stressors. Current methods of bioassessment are not designed for use under this set of constraints. To address this gap, we have developed an assessment method appropriate for well-sampled, heterogeneous systems with many taxa. In the bioassessment described below, we model taxa occurrence as a function of natural environmental gradients, then use residual covariance patterns between all pairs of taxa to estimate the impact of human disturbance across sites as a latent construct. The derivation of the method from an underlying causal model allows the metric value at each site and the associated taxa responses to be partitioned into contributions from a set of putative stressors. We apply this method as a case study to the subtidal benthic invertebrate community of Puget Sound, WA (USA) and demonstrate a partial decomposition of the metric values to a set of stressors including sediment organic carbon, nitrogen, metals, and organic pollutants. While this method provides new opportunities to estimate, communicate, and understand the ecological condition of complex, heterogeneous ecosystems, due to the requirement for broad, detailed data to inform its estimates, it will likely be most appropriate for monitoring programs.

Washington↗
USGS2014

Mercury in the nation's streams - Levels, trends, and implications

Mercury is a potent neurotoxin that accumulates in fish to levels of concern for human health and the health of fish-eating wildlife. Mercury contamination of fish is the primary reason for issuing fish consumption advisories, which exist in every State in the Nation. Much of the mercury originates from combustion of coal and can travel long distances in the atmosphere before being deposited. This can result in mercury-contaminated fish in areas with no obvious source of mercury pollution. Three key factors determine the level of mercury contamination in fish - the amount of inorganic mercury available to an ecosystem, the conversion of inorganic mercury to methylmercury, and the bioaccumulation of methylmercury through the food web. Inorganic mercury originates from both natural sources (such as volcanoes, geologic deposits of mercury, geothermal springs, and volatilization from the ocean) and anthropogenic sources (such as coal combustion, mining, and use of mercury in products and industrial processes). Humans have doubled the amount of inorganic mercury in the global atmosphere since pre-industrial times, with substantially greater increases occurring at locations closer to major urban areas. In aquatic ecosystems, some inorganic mercury is converted to methylmercury, the form that ultimately accumulates in fish. The rate of mercury methylation, thus the amount of methylmercury produced, varies greatly in time and space, and depends on numerous environmental factors, including temperature and the amounts of oxygen, organic matter, and sulfate that are present. Methylmercury enters aquatic food webs when it is taken up from water by algae and other microorganisms. Methylmercury concentrations increase with successively higher trophic levels in the food web—a process known as bioaccumulation. In general, fish at the top of the food web consume other fish and tend to accumulate the highest methylmercury concentrations. This report summarizes selected stream studies conducted by the U.S. Geological Survey (USGS) since the late 1990s, while also drawing on scientific literature and datasets from other sources. Previous national mercury assessments by other agencies have focused largely on lakes. Although numerous studies of mercury in streams have been conducted at local and regional scales, recent USGS studies provide the most comprehensive, multimedia assessment of streams across the United States, and yield insights about the importance of watershed characteristics relative to mercury inputs. Information from other environments (lakes, wetlands, soil, atmosphere, glacial ice) also is summarized to help understand how mercury varies in space and time.

Circular↗
USGS2016

Chaparral

One of the most dynamic California ecosystems is chaparral. Dominated by evergreen, sclerophyllous shrubs and small trees, chaparral is the most extensive vegetation type in the state (Figure 1). The nearly impenetrable tangle of stiff branches of this unusual vegetation inhibits exploration, and as a consequence the public know little about its natural history and unique characteristics. This under-valued ecosystem is recognized instead by the threat of its extensive, high-intensity canopy-burning wildfires that characterize the dry summer and fall seasons of the state. Because urban areas frequently share borders or intermix with chaparral, societal interests often conflict with conservation of this ecosystem, and understanding its history and dynamics are a key to appreciating its importance. In this chapter we emphasize the principal structure and dynamics of this important ecosystem. The long summer rainless period has strong impacts on all organisms and, importantly, the droughts influence the fire regime that characterizes chaparral. An ecosystem currently characterized by a specific drought and wildfire regime can expect significant impacts from climate change. Because of its dominance at lower elevations, chaparral also is frequently found at or near the boundaries of urban developments and metropolitan centers. Attempts to suppress fire also affect chaparral dynamics in the long absence of fire. The conflicts between the impacts of chaparral wildfire and human life and structures has been an aspect of California’s history since the beginning, but as development encroaches ever more into chaparral regions, the conflicts have increased. Consequently, understanding this vegetation is important not only because of its significance in understanding ecological evolution and the ecological services provided by chaparral, but also because of its direct impacts on human settlements.

Book chapter↗
USGS2001

National survey of MTBE and other VOCs in community drinking-water sources

Methyl tert -butyl ether (MTBE) is a volatile organic compound (VOC) that is added to gasoline either seasonally or year round in many parts of the United States to increase the octane level and to reduce carbon monoxide and ozone levels in the air. The chemical properties and widespread use of MTBE can result in contamination of private and public drinking-water sources. MTBE contamination is a concern in drinking water because of the compound's low taste and odor threshold and potential human-health effects. Because of this concern, a survey was initiated in collaboration with researchers and water suppliers. The purpose of this survey is to provide sound, unbiased, scientific information on the occurrence of MTBE and other VOCs in ground water, reservoirs, and rivers that are sources of drinking water used by communities of various sizes throughout the Nation. This fact sheet presents a general description of the survey.

Fact Sheet↗
USGS1997

Progress report on sediment analyses at selected faunal monitoring sites in north-central and northeastern Florida Bay

Florida Bay is a shallow, subtropical lagoon at the southern tip of the Florida peninsula. The 2200 square kilometer, triangular-shaped area is the site of modern carbonate sediment formation and deposition. The intricate ecosystem of the bay has undergone significant changes as the result of natural influences and human intervention. The purpose of this study is to investigate carbonate sediment characteristics and distribution in conjunction with faunal and floral to determine the substrate preferences of associated fauna and flora. The modern data provide the proxy data for down-core analyses of sediments, fauna and flora in order to document ecosystem changes in the bay. Selected sediment samples collected during 1996 from 18 sites in the northeastern and central bay were analyzed for insoluble residues, organic content, total carbonate, and percent of silt and clay sized particles. Insoluble residues range from 0.8% of the sediment in a shell lag to 11.5% with an average of 5.1%. Organic content ranged from a minimum of 1.43% of the sediment to 18.05% with an average of 7.6%. The total carbonate content ranged from 72.56% to 97.81%, averaging 87.98%. The percent silt and clay sized particles ranged from 13.75% to 63.62% for the samples analyzed. The insoluble residue content shows a general trend of decreasing insoluble residues from the northeastern bay toward the southwest. Organic content is variable throughout the bay and does not show a regional trend. Several sites show a trend of higher organic content in the samples collected in February as compared to those collected in July. Lithologic examination indicated that, in addition to the carbonate mud (less than 63mm), sample components included whole and fragmented mollusks, foraminifers, bryozoans, ostracods, and organic matter. The insoluble residues consisted of quartz sand and silt, clays and siliceous fossils. A component of the insoluble residues may be dust derived from Africa and transported to southern Florida by the prevailing winds. This report is preliminary and has not been reviewed for conformity with U.S. Geological Survey editorial standards or with the North American Stratigraphic Code. Any use of trade, product, or firm names is for descriptive purposes only and does not imply endorsement by the U.S. Government.

Open-File Report↗
USGS2004

Mercury hazards from gold mining to humans, plants, and animals

Mercury contamination of the environment from historical and ongoing mining practices that rely on mercury amalgamation for gold extraction is widespread. Contamination was particularly severe in the immediate vicinity of gold extraction and refining operations; however, mercury, especially in the form of water-soluble methylmercury, may be transported to pristine areas by rainwater, water currents, deforestation, volatilization, and other vectors. Examples of gold mining-associated mercury pollution are shown for Canada, the United States, Africa, China, the Philippines, Siberia, and South America. In parts of Brazil, for example, mercury concentrations in all abiotic materials, plants, and animals--including endangered species of mammals and reptiles, collected near ongoing mercury-amalgamation gold mining sites were far in excess of allowable mercury levels promulgated by regulatory agencies for the protection of human health and natural resources. Although health authorities in Brazil are unable to detect conclusive evidence of human mercury intoxication, the potential exists in the absence of mitigation for epidemic mercury poisoning of the mining population and environs. In the United States, environmental mercury contamination is mostly from historical gold mining practices, and portions of Nevada remain sufficiently mercury-contaminated to pose a hazard to reproduction of carnivorous fishes and fish-eating birds. Concentrations of total mercury lethal to sensitive representative natural resources range from 0.1 to 2.0 microg/L of medium for aquatic organisms; from 2,200 to 31,000 microg/kg BW (acute oral) and from 4,000 to 40,000 microg/kg (dietary) for birds; and from 100 to 500 microg/kg BW (daily dose) and from 1,000 to 5,000 microg/kg diet for mammals. Significant adverse sublethal effects were observed among selected aquatic species at water concentrations of 0.03-0.1 microg Hg/L. For some birds, adverse effects, mainly on reproduction, have been associated with total mercury concentrations (microg/kg FW) of 5,000 in feathers, 900 in eggs, and 50-100 in diet, and with daily intakes of 640 microg/kg BW. Sensitive nonhuman mammals showed significant adverse effects of mercury when daily intakes were 250 microg/kg BW, when dietary levels were 1,100 microg/kg, or when tissue concentrations exceeded 1,100 microg/kg. Proposed mercury criteria for protection of aquatic life range from 0.012 microg/L for freshwater life to 0.025 microg/L for marine life; for birds, less than 100 microg/kg diet FW; and for small mammals, less than 1,100 microg/kg FW diet. All these proposed criteria provide, at best, minimal protection.

Archives of Environmental Contamination and Toxico↗
USGS2013

An examination of historic inorganic sedimentation and organic matter accumulation in several marsh types within the Mobile Bay and and Mobile-Tensaw River Delta region

Mass accumulation rates (MAR; g cm -2 y -1 ), linear sedimentation rates (LSR; cm y -1 ), and core geochronology derived from excess lead-210 ( 210 Pb) profiles and inventories measured in six sediment cores collected from marsh sites from the MobileTensaw River Delta and Mobile Bay region record the importance of both continuous and event-driven inorganic sedimentation over the last 120 years. MAR in freshwater marshes varied considerably between sites and through time (0.24 and 1.31 g cm -2 y -1 ). The highest MARs occurred in the 1950s and 1960s and correspond to record discharge events along the Mobile and Tensaw Rivers. In comparison, MAR at salt marsh sites increased almost threefold over the last 120 years (0.05 to 0.18 g cm -2 y -1 or 0.23 to 0.48 cm y -1 ). From 1880 to 1960, organic accumulation remained fairly constant (20%), while intermittent pulses of high inorganic sedimentation were observed following 1960. The pulses in inorganic sedimentation coincide with several major hurricanes (e.g., Hurricanes Camille, Fredric, Georges, and Ivan). The nearly threefold increase in MAR in salt marshes during the last 120 years would thus appear to be partially dependent on inorganic sedimentation from storm events. This study shows that while hurricanes, floods, and other natural hazards are well-known threats to human infrastructure and coastal ecosystems, these events also transport sediment to marshes that help abate other pressures such as sea-level rise (SLR) and subsidence.

Alabama↗
USGS2007

Assessment of biological conditions at selected stream sites in Johnson County, Kansas, and Cass and Jackson Counties, Missouri, 2003 and 2004

Macroinvertebrate samples were collected at 15 stream sites representing 11 different watersheds in Johnson County, Kansas, in 2003 and 2004 to assess biological conditions in streams and relations to environmental variables. Published data from an additional seven stream sites, one in Johnson County, Kansas, and six others in adjacent Cass and Jackson Counties in Missouri also were evaluated. Multimetric scores, which integrated a combination of measures that describe various aspects of biological community abundance and diversity, were used to evaluate and compare the biological health of streams. In addition, for 15 of 16 Johnson County stream sites, environmental data (streamflow, precipitation, and land use) and water- and sediment-quality data (primarily nutrients, indicator bacteria, and organic wastewater compounds) were used in statistical analyses to evaluate relations between macroinvertebrate metrics and variables that may affect them. The information is useful for defining current conditions, evaluating conditions relative to State aquatic-life support and total maximum daily load requirements, evaluating effects of urbanization, developing effective water-quality management plans, and documenting changes in biological condition and water quality. Biological conditions in selected Johnson County streams generally reflected a gradient in the degree of human disturbances upstream from the sites, including percentage of urban and agricultural land use as well as the presence, absence, and proximity of wastewater treatment discharges. In this report, the term gradient is used to describe a continuum in the conditions (biological, environmental, or land use) observed at the study sites. Upstream Blue River sites, downstream from primarily agricultural land use, consistently scored among the sites least impacted by human disturbance, and in some metrics these sites scored higher than the State reference site (Captain Creek). The term impact, as used in this report, refers to a negative biological response at a site associated with one or more human-induced sources of disturbance or stress. However, no sites, including the Captain Creek reference site, met Kansas Department of Health and Environment criteria for full support of aquatic life during the 2 years of sample collection. Upstream sites on Kill and Cedar Creeks also consistently scored among the least impacted. Sites less than 3 miles downstream from municipal wastewater treatment facility discharges (two Indian Creek sites) and sites with no wastewater discharge but with substantial impervious surface area within their respective watersheds (Tomahawk, Turkey, and Brush Creeks) consistently scored among the sites most impacted by human disturbance.

Scientific Investigations Report↗
USGS2023

Informing ASR treatment practices in a Florida aquifer through a human health risk approach

Aquifer storage and recovery (ASR) can augment water supplies and hydrologic flows under varying climatic conditions. However, imposing drinking water regulations on ASR practices, including pre-treatment before injection into the aquifer, remains arguable. Microbial inactivation data— Escherichia coli , Pseudomonas aeruginosa , poliovirus type 1 and Cryptosporidium parvum —were used in a human health risk assessment to identify how the storage time of recharged water in the Floridan Aquifer enhances pathogen inactivation, thereby mitigating the human health risks associated with ingestion. We used a quantitative microbial risk assessment to evaluate the risks for a gastrointestinal infection (GI) and the associated disability-adjusted life years (DALYs) per person per year. The risk of developing a GI infection for drinking water no longer exceeded the suggested annual risk threshold (1 × 10 −4 ) by days 31, 1, 52 and 80 for each pathogen, respectively. DALYs per person per year no longer exceeded the World Health Organization threshold (1 × 10 −6 ) by days 27, <1, 43 and 72. In summary, storage time in the aquifer yields a significant reduction in health risk. The findings emphasize that considering microbial inactivation, caused by storage time and geochemical conditions within ASR storage zones, is critical for recharge water treatment processes.

Florida↗
USGS2016

Recreation, values and stewardship: Rethinking why people engage in environmental behaviors in parks and protected areas

Successfully promoting and encouraging the adoption of environmental stewardship behavior is an important responsibility for public land management agencies. Although people increasingly report high levels of concern about environmental issues, widespread patterns of stewardship behavior have not followed suit (Moore 2002). One concept that can be applied in social science research to explain behavior change is that of values. More specifically, held and assigned values lie at the heart of understanding why people around the world continue to live in unsustainable ways that impact parks and protected areas. A held value is an individual psychological orientation defined by Rokeach as “an enduring belief that a specific mode of conduct or endstate of existence is personally and socially preferable” (1973, 550). Held values are at the core of human cognition, and as such, influence attitudes and behavior. Assigned values on the other hand, according to Brown (1984), are the perceived qualities of an environment that are based on and deduced from held values. In other words, assigned values are considered the material and nonmaterial benefits that people believe they obtain from ecosystems. Held and assigned values predict stewardship behaviors (Figure 1). During the 2013 George Wright Society Conference on Parks, Protected Areas, and Cultural Sites, we organized a session to improve our understanding of why individuals and groups choose to engage in stewardship behaviors that benefit the environment. We used held and assigned values as vehicles to explore what people cared about in diverse landscapes, review select case studies from across the globe, and question how best to incorporate visitor perspectives into protected area management decisions and policymaking. In addition to sharing project results, we also discussed the importance of accounting for multiple and often competing value perspectives, potential ways to integrate disciplinary perspectives on valuing nature, and future directions for social science research and practice. In this paper, we present the results from our session to provide fodder for further contemplation about the timely question of how park and protected area managers can foster values that lead to environmental protection.

Book chapter↗
USGS1996

Environmental setting of benchmark streams in agricultural areas of eastern Wisconsin

This report describes the environmental setting of 20 benchmark streams in agricultural areas of eastern Wisconsin that are part of the Western Lake Michigan Drainages, National Water-Quality Assessment Program. Benchmark streams are defined as those that show minimal adverse effects from human activity, and they were selected on the basis of field reconnaissance and the following criteria: (1) available invertebrate or fisheries data that indicated good to excellent water quality, (2) instream habitat restoration for fisheries enhancement, and (3) land management to protect riparian vegetation. Information gathered from these benchmark sites can be used as a standard of reference to compare the health of other streams in agricultural areas on the basis of aquatic-biota communities, habitat, and water-quality characteristics. The information included in this report serves as background information that will be useful for a series of studies at these benchmark-stream sites in the Western Lake Michigan Drainages study unit as part of the National Water-Quality Assessment Program. Four relatively homogeneous units (RHU's) in agricultural areas that differed in bedrock and surficial geology were selected for study. RHU 1 (clayey surficial deposits over carbonate bedrock) and RHU 3 (sandy-till surficial deposits over carbonate bedrock) are in adjacent agricultural areas in the Southeastern Wisconsin Till Plains ecoregion. RHU 20 (sandy/sand and gravel surficial deposits over igneous and metamorphic bedrock) and RHU 26 (sandy/sand and gravel surficial deposits over sandstone bedrock) are in adjacent areas of agriculture and mixed forests in the North Central Hardwood Forests ecoregion. Differences in land use/land cover, and riparian vegetation and instream habitat characteristics are presented. Summaries of field measurements of water temperature, pH, specific conductance and concentrations of dissolved oxygen, total organic plus ammonia nitrogen, dissolved ammonium, nitrate plus nitrte as nitrogen, total phosphorus, dissolved orthophosphate, and atrazine are listed. Concentrations of dissolved oxygen for the sampled streams ranged from 6 A to 14.3 and met the standards set by the Wisconsin Department of Natural Resources (WDNR) for supporting fish and aquatic life. Specific conductance ranged from 98 to 753 u,Scm with values highest in RHU's 1 and 3, where streams are underlain by carbonate bedrock. Median pH did not vary greatly among the four RHU's and ranged from 6.7 to 8.8 also meeting the WDNR standards. Concentrations of total organic plus ammonia nitrogen, dissolved ammonium, total phosphorus, and dissolved orthophosphate show little variation between streams and are generally low, compared to concentrations measured in agriculturally-affected streams in the same RHU's during the same sampling period. Concentrations of the most commonly used pesticide in the study unit, atrazine, were low in all streams, and most concentrations were below trn 0.1 u,g/L detection limit. Riparian vegetation for the benchmark streams were characterized by lowland species of the native plant communities described by John T. Curtis in the "Vegetation of Wisconsin." Based on the environmental setting and water-quality information collected to date, these streams appear to show minimal adverse effects from human activity.

Wisconsin↗
USGS2007

Restoration of mangrove plantations and colonisation by native species in Leizhou bay, South China

To examine the natural colonisation of native mangrove species into remediated exotic mangrove stands in Leizhou Bay, South China, we compared soil physical-chemical properties, community structure and recruitments of barren mangrove areas, native mangrove species plantations, and exotic mangrove species-Sonneratia apetala Buch.Ham-between plantations and natural forest. We found that severely degraded mangrove stands could not regenerate naturally without human intervention due to severely altered local environments, whereas some native species had been recruited into the 4-10 year S. apetala plantations. In the first 10 years, the exotic species S. apetala grew better than native species such as Rhizophora stylosa Griff and Kandelia candel (Linn.) Druce. The mangrove plantation gradually affected soil physical and chemical properties during its recovery. The exotic S. apetala was more competitive than native species and its plantation was able to restore soil organic matter in about 14 years. Thus, S. apetala can be considered as a pioneer species to improve degraded habitats to facilitate recolonisation by native mangrove species. However, removal to control proliferation may be needed at late stages to facilitate growth of native species. To ensure sustainability of mangroves in South China, the existing mangrove wetlands must be managed as an ecosystem, with long-term scientific monitoring program in place. ?? 2007 The Ecological Society of Japan.

Ecological Research↗
USGS2009

Probability of Elevated Nitrate Concentrations in Groundwater in the Eagle River Watershed Valley-Fill Aquifer, Eagle County, North-Central Colorado, 2006-2007

This raster data set delineates the predicted probability of elevated nitrate concentrations in groundwater in the Eagle River watershed valley-fill aquifer, Eagle County, North-Central Colorado, 2006-2007. This data set was developed by a cooperative project between the U.S. Geological Survey, Eagle County, the Eagle River Water and Sanitation District, the Town of Eagle, the Town of Gypsum, and the Upper Eagle Regional Water Authority. This project was designed to evaluate potential land-development effects on groundwater and surface-water resources so that informed land-use and water management decisions can be made. This groundwater probability map and its associated probability maps was developed as follows: (1) A point data set of wells with groundwater quality and groundwater age data was overlaid with thematic layers of anthropogenic (related to human activities) and hydrogeologic data by using a geographic information system to assign each well values for depth to groundwater, distance to major streams and canals, distance to gypsum beds, precipitation, soils, and well depth. These data then were downloaded to a statistical software package for analysis by logistic regression. (2) Statistical models predicting the probability of elevated nitrate concentrations, the probability of unmixed young water (using chlorofluorocarbon-11 concentrations and tritium activities), and the probability of elevated volatile organic compound concentrations were developed using logistic regression techniques. (3) The statistical models were entered into a GIS and the probability map was constructed.

Data Series↗
USGS2009

Probability of Unmixed Young Groundwater (defined using chlorofluorocarbon-11 concentrations and tritium activities) in the Eagle River Watershed Valley-Fill Aquifer, Eagle County, North-Central Colorado, 2006-2007

This raster data set delineates the predicted probability of unmixed young groundwater (defined using chlorofluorocarbon-11 concentrations and tritium activities) in groundwater in the Eagle River watershed valley-fill aquifer, Eagle County, North-Central Colorado, 2006-2007. This data set was developed by a cooperative project between the U.S. Geological Survey, Eagle County, the Eagle River Water and Sanitation District, the Town of Eagle, the Town of Gypsum, and the Upper Eagle Regional Water Authority. This project was designed to evaluate potential land-development effects on groundwater and surface-water resources so that informed land-use and water management decisions can be made. This groundwater probability map and its associated probability maps were developed as follows: (1) A point data set of wells with groundwater quality and groundwater age data was overlaid with thematic layers of anthropogenic (related to human activities) and hydrogeologic data by using a geographic information system to assign each well values for depth to groundwater, distance to major streams and canals, distance to gypsum beds, precipitation, soils, and well depth. These data then were downloaded to a statistical software package for analysis by logistic regression. (2) Statistical models predicting the probability of elevated nitrate concentrations, the probability of unmixed young water (using chlorofluorocarbon-11 concentrations and tritium activities), and the probability of elevated volatile organic compound concentrations were developed using logistic regression techniques. (3) The statistical models were entered into a GIS and the probability map was constructed.

Data Series↗