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At least 1,117 records · Page 62Linked to original sources
USGS2020

Generalized models to estimate carbon and nitrogen stocks of organic soil horizons in Interior Alaska

Boreal ecosystems comprise one tenth of the world’s land surface and contain over 20 % of the global soil carbon (C) stocks. Boreal soils are unique in that its mineral soil is covered by what can be quite thick layers of organic soil. These organic soil layers, or horizons, can differ in their state of decomposition, source vegetation, and disturbance history. These differences result in varying soil properties (bulk density, C concentration, and nitrogen (N) concentration) among soil horizons. Here we summarize these soil properties, as represented by over 3000 samples from Interior Alaska, and examine how soil drainage and stand age affect these attributes. The summary values presented here can be used to gap-fill large datasets when important soil properties were not measured, provide data to initialize process-based models, and validate model results. These data are available at https://doi.org/10.5066/P960N1F9 (Manies, 2019).

Alaska↗
USGS2022

Stormwater reduction and water budget for a rain garden on sandy soil, Gary, Indiana, 2016–18

Stormwater reduction measures, or green infrastructure, were implemented in the parking area at Gary City Hall, Gary, Indiana, with the intention of reducing stormwater discharge to the sewers. A study area, including a centrally located rain garden and the surrounding paved surfaces and green space, was instrumented during both a preconstruction and a postconstruction period to (1) develop water budgets to improve understanding of the rain garden hydrology and (2) determine the quantity of stormwater runoff that was diverted and retained by the green infrastructure instead of reaching the combined storm and sanitary sewer. The study was focused on warm-season precipitation and was monitored during spring, summer, and fall of 2016, 2017 and 2018. Before construction of the rain garden in the parking lot of Gary City Hall in 2017, nearly all precipitation was conveyed away from the parking lot by underground drains, discharged to the sewer, and treated as sanitary waste at the Gary Sanitary District’s treatment plant or discharged directly to local waterways if stormflow exceeded capabilities of the sewage treatment plant. A goal of the Great Lakes Restoration Initiative is the reduction of sewer overflows to local waterways to improve the quality of water entering the Great Lakes. Cities such as Gary benefit financially and environmentally by reducing discharges of stormwater runoff to the sewer system, eliminating the need for treatment. Before implementation of green infrastructure at Gary City Hall, approximately 25 percent of precipitation (approximately 10,200 cubic feet) discharged as stormwater to the sewers through the parking lot drain. After implementation, 2 percent of precipitation discharged to the sewers. For the spring, summer, and fall seasons of 2017 and 2018, 21–24 percent (about 10,700–19,700 cubic feet) of precipitation was captured by the newly installed rain garden. Stormwater discharged to the rain garden infiltrated the sandy soil and was later evaporated from the soil surface, was transpired by plants, or recharged the underlying groundwater aquifer. The percent reduction in stormwater discharged to the storm sewer after the construction of the rain garden was 80.3 percent, equating to approximately 21,400 and 39,300 gallons of stormwater in 2017 and 2018, respectively.

Indiana↗
USGS2017

The interaction of climate change and methane hydrates

Gas hydrate, a frozen, naturally-occurring, and highly-concentrated form of methane, sequesters significant carbon in the global system and is stable only over a range of low-temperature and moderate-pressure conditions. Gas hydrate is widespread in the sediments of marine continental margins and permafrost areas, locations where ocean and atmospheric warming may perturb the hydrate stability field and lead to release of the sequestered methane into the overlying sediments and soils. Methane and methane-derived carbon that escape from sediments and soils and reach the atmosphere could exacerbate greenhouse warming. The synergy between warming climate and gas hydrate dissociation feeds a popular perception that global warming could drive catastrophic methane releases from the contemporary gas hydrate reservoir. Appropriate evaluation of the two sides of the climate-methane hydrate synergy requires assessing direct and indirect observational data related to gas hydrate dissociation phenomena and numerical models that track the interaction of gas hydrates/methane with the ocean and/or atmosphere. Methane hydrate is likely undergoing dissociation now on global upper continental slopes and on continental shelves that ring the Arctic Ocean. Many factors—the depth of the gas hydrates in sediments, strong sediment and water column sinks, and the inability of bubbles emitted at the seafloor to deliver methane to the sea-air interface in most cases—mitigate the impact of gas hydrate dissociation on atmospheric greenhouse gas concentrations though. There is no conclusive proof that hydrate-derived methane is reaching the atmosphere now, but more observational data and improved numerical models will better characterize the climate-hydrate synergy in the future.

Reviews of Geophysics↗
USGS2025

Aridity reduces lag times between aquatic and terrestrial dry-down among watersheds and across years in the northwest US

Landscapes encompass both aquatic and terrestrial ecosystems that experience the same climate but may respond to climate in divergent ways. For example, the time lag between seasonal dry-down of terrestrial soil moisture and decline in streamflow has important implications for species and ecosystem processes across the aquatic–terrestrial interface. How these lags between aquatic and terrestrial hydrology vary with climate and spatial location within watersheds remains largely unexplored. Here, we examine seasonal patterns of aquatic–terrestrial dry-down across seven watersheds in the northwestern USA, spanning a wide range of aridity. We compared daily streamflow data from USGS gages at watershed outlets with simulated daily soil moisture (1979–2020) from multiple locations within each watershed. In all watersheds, annual dry cycles progressed sequentially through the following features: evapotranspiration, precipitation, shallow soil moisture, deep soil moisture, and finally streamflow. Seasonal streamflow minima lagged behind soil moisture minima for shorter durations in more arid watersheds and drier years. Within watersheds, lag times varied spatially due to interactions between elevation and aridity, with short lags in low-elevation soils near streams in arid watersheds and longer lags in less arid watersheds. Collectively, these results indicate shorter lags between seasonal aquatic and terrestrial dry periods in drier watersheds and years, and show that these tighter linkages are spatially aggregated in drier watersheds. The co-occurrence of seasonally dry conditions in both aquatic and terrestrial systems under increasing aridification is likely to intensify stressors on ecosystems and services. Recognizing these patterns may be critical for predicting ecosystem vulnerabilities and informing adaptation strategies to mitigate the impacts of seasonally dry conditions.

Montana, Oregon, Wyoming↗
USGS1969

Compilation of hydrologic data, Green Creek, Brazos River basin, Texas, 1966

In 1950 the U. S. Soil Conservation Service began construction of floodwater-retarding structures in Texas under authorities granted by the Congress. These authorities provide, where economically feasible, that the program be applied to tributary watersheds of 240,000 acres or less. The usual practice has been to control flood runoff from approximately 50 percent of the watershed by a system of floodwater-retarding structures located on headwater subwatersheds of generally less than 10 square miles.

Texas↗
USGS2009

Coastal Circulation and Sediment Dynamics in War-in-the-Pacific National Historical Park, Guam; measurements of waves, currents, temperature, salinity, and turbidity, June 2007-January 2008

Flow in and around coral reefs affects a number of physical, chemical and biologic processes that influence the health and sustainability of coral reef ecosystems. These range from the residence time of sediment and contaminants to nutrient uptake and larval retention and dispersal. As currents approach a coast they diverge to flow around reef structures, causing high horizontal and vertical shear. This can result in either the rapid advection of material in localized jets, or the retention of material in eddies that form in the lee of bathymetric features. The high complexity and diversity both within and between reefs, in conjunction with past technical restrictions, has limited our understanding of the nature of flow and the resulting flux of physical, chemical, and biologic material in these fragile ecosystems. Sediment, nutrients, and other pollutants from a variety of land-based activities adversely impact many coral reef ecosystems in the U.S. and around the world. These pollutants are transported in surface water runoff, groundwater seepage, and atmospheric fallout into coastal waters, and there is compelling evidence that the sources have increased globally as a result of human-induced changes to watersheds. In Guam, and elsewhere on U.S. high islands in the Pacific and Caribbean, significant changes in the drainage basins due to agriculture, feral grazing, fires, and urbanization have in turn altered the character and volume of land-based pollution released to coral reefs. Terrigenous sediment run-off (and the associated nutrients and contaminants often absorbed to it) and deposition on coral reefs are recognized to potentially have significant impact on coral health by blocking light and inhibiting photosynthesis, directly smothering and abrading coral, and triggering increases in macro algae. Studies that combine information on watershed, surface water- and groundwater-flow, transport and fate of sediment and other pollutants in the reef environment, and their impact on reef health and ecology are essential for effective reef management. Two of the main anthropogenic activities along west-central Guam's coastline that may impact the region's coral reef ecosystems include pollution and coastal land use/development, as discussed in the review by Porter and others (2005). The pollution threats include point-sources, such as municipal wastewater (Northern District, Hagatna, Naval Station Guam, and Agat-Santa Rita Waster Water Treatment Plants), cooling water (Tanguisson Steam and Cabras Power Plants), and numerous storm water, ballast water, and tank bottom draw outfalls; nonpoint sources include septic systems, urban runoff, illegal dumping, and groundwater discharges. Poor land-use practices include development without the use of runoff management measures, increased areal extent of impervious surfaces and decreased extent of vegetative barriers, and recreational off-road vehicle use. Furthermore, feral ungulates and illegal wildfires remove protective vegetative cover and generally result in increased soil erosion. While anthropogenic point-sources have been reduced in many areas due to better management practices, nonpoint sources have either stayed constant or increased. Between 1975 and 1999, it is estimated that Guam lost more than a quarter of its tree cover, and more than 750 wildfires each year have resulted in a greater proportion of badlands and other erosion-prone land surfaces with high erosion rates (Forestry and Soil Resources Division, 1999). Approximately 1.8 square kilometers (km2) of Asan Bay, west-central Guam, lies within the National Park Service's (NPS) War-in-the-Pacific National Historical Park's (WAPA) Asan Unit; the bay is the sink for material coming out of the Asan watershed. Anthropogenic modifications of the watersheds adjacent to Asan Bay, which include intentionally-set wildfires, construction, and agriculture (Minton, 2005), are believed to have increased over the past 25

Open-File Report↗
USGS2018

Promoting synergy in the innovative use of environmental data—Workshop summary

From December 2 to 4, 2015, NatureServe and the U.S. Geological Survey organized and hosted a biodiversity and ecological informatics workshop at the U.S. Department of the Interior in Washington, D.C. The workshop objective was to identify user-driven future directions and areas of collaboration in advanced applications of environmental data applied to forecasting and decision making for the sustainability of biodiversity and ecosystem services. Substantial effort to recruit attendees from diverse Federal, State, and private sector organizations successfully attracted participants from 20 Federal agencies and 48 different institutions in the academic, nonprofit, State government, and commercial sectors; the total number of attendees ranged from 100 to 144 during the 3-day workshop. The first one-half of the workshop was divided into 7 plenary sessions and 3 sets of lightning talk sessions organized by sector, providing 48 oral and visual plenary presentations that shared diverse perspectives on biodiversity and ecological informatics, including original biospatial analyses from 6 graduate student map contest winners. The second one-half of the workshop focused on 10 breakout sessions with participant-driven themes from the environmental data sphere and concluded with an address by the Director of the U.S. Fish and Wildlife Service. The workshop was structured to encourage interactivity. About 80–90 percent of attendees provided direct feedback using clicker devices for specific questions related to biodiversity and ecological data uses and needs, and 10 breakout session leaders shared the highlights of their group discussions during the final workshop plenary sessions. Participants were encouraged to use the Twitter hashtag #ShareUrData. Over lunch on day 2 there were 20 simultaneous presentations of tools and apps during a special “Tools Café” session. The 10 participant-defined breakout session topics are listed below: Ecosystem services and ecological indicators Inventory and monitoring Biogeographic map of the Nation Pollinators Invasive species Remote sensing Drivers of agricultural change Citizen science Climate Hydrology and watersheds Numerous common themes that emerged from the workshop include the following: The vital importance of completing foundational environmental datasets that are nationally consistent and are essential to multiple sectors, such as the Soil Survey Geographic database high-resolution soils data, a minimum 5-meter resolution digital elevation model, national hydrographic data, high-resolution land cover data, time series high-resolution spatial climate data from historical to future time steps, and a national wetland inventory. Improved, nationally consistent environmental datasets (integrated with targeted observations) will dramatically advance forecasting capacity and support early warning systems (that is, drought, forest disease); however, multiagency coordination should focus on decision support tools that convey appropriate actions and responses to adapt to, and mitigate, potential negative consequences. Digitizing and providing access to the vast stores of underused historical data that can be leveraged for this purpose is of national importance. Modern computational techniques and the ever-increasing flow of environmental data from ground and remote observations can support improved understanding of environmental change. Success of understanding patterns of change for decision making requires establishing baselines from which change can be measured. The value of digitized historical data is greater than ever before. There is a need to recognize the multifaceted potential of citizen science to engage the public in resource stewardship, to create the next generation of science, technology, engineering, math, and environmental leaders, and to have sufficient field personnel to monitor environmental trends, including early detection of alien invasive species, phenological shifts, shifting distribution and abundance of indicator species, and species inventories. The Federal government has an essential role in creating the infrastructure to dramatically improve mobilization of citizen science (and other) data by fostering the following: creation of data standards, creation of nationally consistent framework datasets, vertical integration of observation data, visualization and dissemination of aggregated datasets, and calculation and communication of derived trends. Current and near future trends in the availability of remotely sensed data (rapid expansion of satellite fleets and drones) is revolutionizing access to near-real-time ecological data. Targeted integration with ground-based observations and instrumentation has an extremely valuable role in validating remotely sensed data, filling data gaps, improving data quality, and fully realizing the potential of the near-real-time monitoring of environmental indicator trends. Integrated management of environmental data at the landscape scale is required even as specific actions on the ground are largely local in nature. The workshop highlighted numerous success stories; however, almost every breakout group pointed out the still-too-fragmented nature of the current data landscape. Management and delivery of the necessary data, tools, and analyses to sustain our Nation’s environmental capital must be a collaborative effort between Federal, State, and local governments, academia, nonprofits, and the commercial sector, even though the responsibilities of each sector are different.

Open-File Report↗
USGS1984

Preconstruction and simulated postconstruction ground-water levels at urban centers in the Red River Navigation Project area, Louisiana

The Red River Valley in Louisiana is 3 to 10 miles wide and is underlain by the Red River alluvial aquifer. This aquifer is in hydraulic connection with the Red River. Precipitation infiltrates the aquifer and water discharges from the aquifer at the Red River and major tributaries. Construction of locks and dams along the Red River will cause new, higher minimum stages for the river for each of the pools. Water levels will rise and outflow from the alluvial aquifer to the river after construction of the locks and dams will be at higher elevations because of the new river stages. Mathematical models of the stream-aquifer system simulate the effects of the lock and dam system for plan B-3, modified. Water-level changes in the aquifer in response to the changes imposed by the system are greatest near the river and are progressively smaller away from the river. The saturated zone in the fine-grained material overlying the aquifer provides the principal potential impact on structures and vegetation in urban areas. As water levels in the aquifer rise, the saturated zone above the aquifer will decrease the thickness. The soil zone in low areas in some communities will be waterlogged. (USGS)

Louisiana↗
USGS2021

Methods of data collection and analysis for an assessment of karst aquifer systems between Albany and Buffalo, New York

The U.S. Geological Survey, in cooperation with the New York State Department of Environmental Conservation, catalogued aquifers and closed depressions in a karst-prone area between Albany and Buffalo, New York to provide resource managers information to more efficiently manage and protect groundwater resources. The New York State Department of Environmental Conservation has been working with the agricultural industry to raise awareness of karst aquifer contamination susceptibility and how to reduce effects on surface water and groundwater resources, especially in karst areas. There is also a need to make industries, State and local regulators, planners, and the public aware of New York’s karst resources to properly protect and manage these resources and the quality of surface water and groundwater that flows through the karst aquifer. Publicly available geospatial data were identified, collated, and analyzed for a region of karst terrain extending from Albany to Buffalo. The region was divided into 10 subareas. A series of geospatial datasets were assembled to determine the location and extent of karstic rock; bedrock geology and depth to bedrock; average water-table configuration; surficial geology; soil type, thickness, and hydraulic conductivity; land cover; and closed depressions in the land surface. Repeated glaciation and recession across New York have left the landscape pockmarked with closed depressions, which may or may not be related to the underlying bedrock. Closed depressions in areas where carbonate or evaporite karst are present are of primary concern to this study because of the increased potential of karst aquifer contamination from focused recharge. Closed depressions present in areas not associated with karst bedrock can also be evaluated to better understand their ability to transmit surface water to the groundwater system. Information on closed depressions can be used to develop land-management plans to protect local and regional water resources.

New York↗
USGS2017

Interannual to multidecadal climate forcings on groundwater resources of the U.S. West Coast

Study region The U.S. West Coast, including the Pacific Northwest and California Coastal Basins aquifer systems. Study focus Groundwater response to interannual to multidecadal climate variability has important implications for security within the water–energy–food nexus. Here we use Singular Spectrum Analysis to quantify the teleconnections between AMO, PDO, ENSO, and PNA and precipitation and groundwater level fluctuations. The computer program DAMP was used to provide insight on the influence of soil texture, depth to water, and mean and period of a surface infiltration flux on the damping of climate signals in the vadose zone. New hydrological insights for the region We find that PDO, ENSO, and PNA have significant influence on precipitation and groundwater fluctuations across a north-south gradient of the West Coast, but the lower frequency climate modes (PDO) have a greater influence on hydrologic patterns than higher frequency climate modes (ENSO and PNA). Low frequency signals tend to be preserved better in groundwater fluctuations than high frequency signals, which is a function of the degree of damping of surface variable fluxes related to soil texture, depth to water, mean and period of the infiltration flux. The teleconnection patterns that exist in surface hydrologic processes are not necessarily the same as those preserved in subsurface processes, which are affected by damping of some climate variability signals within infiltrating water.

California, Oregon, Washington↗
USGS2019

An integrative GIS approach to analyzing the impacts of septic systems on the coast of Florida, USA

An estimated 2.7 million septic systems in Florida, USA are potential ground and surface water contaminant sources that may affect environmental and human health. This study examined the spatial distribution of septic systems, coastal surface water contamination, and related environmental factors of coastal Florida watersheds at the 8-digit hydrologic unit code level. Hydrology, in situ sampling data, and other ancillary data were combined in a geographic information system to examine spatial relationships. Spatial distribution data were correlated to nitrogen, Enterococci counts, and beach closures tabulated since 2000, 2007, and 2012. Significant positive correlations (α = 0.05) with nitrogen and Enterococci counts were consistent for percent agricultural cover, percent combined urban and agricultural cover, septic tank density, population density, and septic tank density in poorly drained soils. Beach closures since 2012 were significantly positively correlated (α = 0.05) to average impervious cover (IC) and percent urbanization. Statistics indicated that Enterococci counts, nitrogen, and beach closures may be related to specific environmental factors and septic tank densities. The combination of septic tanks in urban regions with high IC prone to elevated runoff could also be a factor in surface water contamination. Data availability was also highlighted as a limitation due to infrequent spatial and temporal sampling.

Florida↗
USGS1974

Hydrologic Unit Map -- 1974, State of Michigan

This map and accompanying table show Hydrologic Units that are basically hydrographic in nature. The Cataloging Units shown will supplant the Cataloging Units previously used by the U.S. Geological Survey in its Catalog of Information on Water Data (1966-72). The previous U.S. Geological Survey Catalog-Indexing System was by map number and letter, such as 49 M. The boundaries shown have been adapted from "The Catalog of Information on Water Data" (1972), "Water Resources Regions and Subregions for the National Assessment of Water and Related Land Resources" by the U.S. Water Resources Council (1970), " River Basins of the United States" by the U.S. Soil Conservation Service (1963, 1970), "River Basin Maps Showing Hydrologic Stations" by the Inter-Agency Committee on Water Resources, Subcommittee on Hydrology (1961), and States planning maps.

Michigan↗
USGS1976

Hydrologic Unit Map - 1974, state of Montana

This map and accompanying table show Hydrologic Units that are basically hydrographic in nature. The Cataloging Units shown will supplant the Cataloging Units previously used by the U.S. Geological Survey in its Catalog of Informaiton on Water Data (1966-72). The previous U.S. Geological Survey Catalog-Indexing System was by map number and letter, such as 49M. The boundaries as shown have been adapted from "The Catalog of Information on Water Data" (1972), "Water Resources Regions and Subregions for the National Assessment of Water and Related Land Resources" by the U.S. Water Reseources Council (1970), "River Basins of the United States" by the U.S. Soil Conservation Service ((1963, 1970), "River Basin Maps Showing Hydrologic Stations" by the Inter-Agency Committee on Water Resources, Subcommittee on Hydrology (1961), and State planning maps.

Montana↗
USGS1974

Hydrologic unit map:1974, State of Utah

This map and accompanying table show Hydrologic Units that are basically hydrographic in nature. The Cataloging Units shown will supplant the Cataloging Units previously used by the U.S. Geological Survey in its Catalog of Information on Water Data (1966-72). The previous U.S. Geological Survey Catalog-Indexing System was by map number and letter, such as 49M. the boundaries as shown have been adapted from “the Catalog of Information on Water Data” (1972), “Water Resources Regions and Subregions for the National Assessment of Water and Related Land Resources” by the U.S. Water Resources Council (1970), “River Basins of the United States” by the U.S. Soil Conservation Service (1963, 1970), “River Basin Maps Showing Hydrologic Stations” by the Inter-Agency Committee on Water Resourres, Subcommittee on hydrology (1961), and State planning maps.

Utah↗
USGS1977

Acid-rain weathering of a metasedimentary rock basin, Herkimer County, New York

A geochemical balance of major chemical constituents of precipitation inflow with those of surface-water outflow was used to evaluate the effect of acid rainfall (average pH = 4.3) on weathering rates of metasedimentary rocks underlying a surface-water basin in New York State. Precipitation samples and surface-water samples show that approximately 45 percent of the net cation outflow is due to weathering by precipitation acidity. The remaining 55 percent of the cation load in the outflow is attributed to interactions between atmosphere, rock, and soil water in the unsaturated zone. Comparison of the acidity of acid precipitation and air-equilibrated distilled water suggests that since preindustrial time, precipitation acidity has probably increased weathering rates for this basin approximately 75 percent. The increased acidity of the precipitation may also increase the rate of dissolution of heavy metals from water-piping systems.

New York↗
USGS2000

Sensitivity of ground water to contamination in Lawrence County, South Dakota

Ground-water supplies in Lawrence County, South Dakota, can be contaminated by agricultural, urban, suburban, commercial, and industrial land uses. To address this issue, the U.S. Geological Survey in cooperation with Lawrence County and the City of Spearfish mapped the sensitivity of ground water to contamination in Lawrence County. Sensitivity of ground water to contamination was determined by delineating hydrogeologic settings with common hydrogeologic characteristics as described in the DRASTIC method, developed by the U.S. Environmental Protection Agency and the National Water Well Association. Within the framework of 11 hydrogeologic settings, sensitivity to contamination was ranked for six intrinsic hydrogeologic characteristics: (1) aquifer media, (2) unsaturated media (3) hydraulic conductivity, (4) recharge rate, (5) depth to water, and (6) land-surface slope. The rating conventions of DRASTIC were modified to provide a relative ranking of hydrogeologic characteristics without assignment of a combined numerical score. Soil characteristics were not included as a map layer because detailed digital data were not available; however, the general distribution of two soil characteristics were shown. A total of 956 polygons were delineated and assigned a sensitivity-unit code that represented unique groups of sensitivity rank for the six intrinsic hydrogeologic characteristics. The polygons were created by overlaying and intersecting maps that describe the geology, precipitation, land-surface elevation, and depth to water using a geographic information system. Thirty drainage areas upstream from potential streamflow-loss zones were delineated to describe an additional mechanism of transport of potential contamination. The sensitivity of ground water to contamination was presented on a 1:100,000-scale map with code and label explanations. Limitations of the sensitivity map are described to facilitate appropriate use of the map as a screening tool to compare sensitivity to contamination.

Water-Resources Investigations Report↗
USGS1997

Rock-stratigraphic nomenclature, lithology, and subcrop area of the Galena-Platteville bedrock unit in Illinois and Wisconsin

The Galena-Platteville bedrock unit is a dependable source of ground water for many private well owners and some municipal-water-supply systems in northern Illinois (Hackett, 1960) and in Wisconsin. The carbonate lithology of the unit contributes to the availability of ground water and also to the susceptibility of the unit to ground-water contamination. Susceptibility to contamination is greatest in areas where the unit is overlain by only a thin layer (less than 50 feet) of soil or unconsolidated glacial deposits. Within the study area in Illinois and Wisconsin (fig. 1), volatile organic compounds and other contaminants have been detected in groundwater samples from various sites (Kay and others, 1989; Mills, 1993a, 1993b; Kay and others, 1994). Known and suspected sources of contaminants are numerous, including landfills and industrial facilities. To determine the possible effects of contamination on the ground-water supply, an understanding of the regional hydrogeologic framework of the Galena-Platteville bedrock unit is needed. Published map and point data describing the geologic and hydrologic properties of the Galena-Platteville bedrock unit are available from many sources. The U.S. Geological Survey, in cooperation with the U.S. Environmental Protection Agency, Region 5, has selected and compiled pertinent data. The objective of this study is to publish these data in a series of concise map reports and a bibliographic report listing available sources of information by county for the Galena-Platteville bedrock unit. Investigators involved in site-specific studies within the subcrop area will be able to utilize these reports to design effective site investigations. This report presents the rock-stratigraphic nomenclature of the lithologic units that make up the Galena-Platteville bedrock unit (fig.2) and provides a brief, generalized description of the lithologic characteristics of each unit. Sources with more detailed descriptions of lithology can be found below in SELECTED REFERENCES. Figure 3 is a map, created from published maps of various scales, showing the areal extent of the Galena-Platteville subcrop and major known geologic structural features in Illinois and Wisconsin. The subcrop area of the Galena-Platteville bedrock unit is that area where the unit crops out, or is the uppermost bedrock unit and is overlain by soil or glacial deposits. The unit is present at depth under younger bedrock units south and east of the subcrop area and is absent north and west of the subcrop area. Data sources used to prepare the map are included in SELECTED REFERENCES.

Illinois, Wisconsin↗
USGS2017

Tracking the fate of nitrate through pulse-flow wetlands: A mesocosm scale 15N enrichment tracer study

Quantitative information about the fate of applied nitrate (NO 3 -N) in pulse-flow constructed wetlands is essential for designing wetland treatment systems and assessing their nitrogen removal services for agricultural and stormwater applications. Although many studies have documented NO 3 -N losses in wetlands, controlled experiments indicating the relative importance of different processes and N sinks are scarce. In the current study, 15 NO 3 -N isotope enrichment tracer experiments were conducted in wetland mesocosms of two different wetland soil types at two realistic agricultural NO 3 -N source loads. The 15 N label was traced from the source NO 3 -N into plant biomass, soil (including organic matter and ammonium), and N-gas constituents over 7–10 day study periods. All sinks responded positively to higher NO 3 -N loading. Plant uptake exceeded denitrification 2–3 fold in the low NO 3 -N loading experiments, while both fates were nearly equivalent in the high loading experiments. One to two years later, soils largely retained the assimilated tracer N, whereas plants had lost much of it. Results demonstrated that plant and microbial assimilation in the soil (temporary N sinks) can exceed denitrification (permanent N loss) in pulse-flow environments and must be considered by wetland designers and managers for optimizing nitrogen removal potential.

Ecological Engineering↗