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Pesticides in ground water - Carbon County, Wyoming, 2004-2005

In 1991, members of local, State, and Federal governments, as well as industry and interest groups, formed the Ground-water and Pesticide Strategy Committee to prepare the State of Wyoming's generic Management Plan for Pesticides in Ground Water. Part of this management plan is to sample and analyze Wyoming's ground water for pesticides. In 1995, the U.S. Geological Survey, in cooperation with the Ground-water and Pesticide Strategy Committee, began statewide implementation of the sampling component of the State of Wyoming's generic Management Plan for Pesticides in Ground Water. During 2004-2005, baseline monitoring was conducted in Carbon County. This fact sheet describes and summarizes results of the baseline monitoring in Carbon County.

Wyoming↗

A Study of the Connection Among Basin-Fill Aquifers, Carbonate-Rock Aquifers, and Surface-Water Resources in Southern Snake Valley, Nevada

The Secretary of the Interior through the Southern Nevada Public Lands Management Act approved funding for research to improve understanding of hydrologic systems that sustain numerous water-dependent ecosystems on Federal lands in Snake Valley, Nevada. Some of the streams and spring-discharge areas in and adjacent to Great Basin National Park have been identified as susceptible to ground-water withdrawals (Elliott and others, 2006) and research has shown a high potential for ground-water flow from southern Spring Valley into southern Snake Valley through carbonate rocks that outcrop along a low topographic divide known as the Limestone Hills (Welch and others, 2007). Comprehensive geologic, hydrologic, and chemical information will be collected and analyzed to assess the hydraulic connection between basin-fill aquifers and surface-water resources, water-dependent ecological features, and the regional carbonate-rock aquifer, the known source of many high-discharge springs. Understanding these connections is important because proposed projects to pump and export ground water from Spring and Snake Valleys in Nevada may result in unintended capture of water currently supplying springs, streams, wetlands, limestone caves, and other biologically sensitive areas (fig. 1). The methods that will be used in this study may be transferable to other areas in the Great Basin. The National Park Service, Bureau of Land Management, U.S. Fish and Wildlife Service, and U.S. Forest Service submitted the proposal for funding this research to facilitate science-based land management. Scientists from the U.S. Geological Survey (USGS) Water Resources and Geologic Disciplines, and the University of Nevada, Reno, will accomplish four research elements through comprehensive data collection and analysis that are concentrated in two distinct areas on the eastern and southern flanks of the Snake Range (fig. 2). The projected time line for this research is from July 2008 through September 2011.

Fact Sheet↗

Mountain pine beetle impacts on vegetation and carbon stocks

In the Southern Rocky Mountains, an epidemic outbreak of mountain pine beetle (Dendroctonus ponderosae; MPB) has caused levels of tree mortality unprecedented in recorded history. The impacts of this mortality on vegetation composition, forest structure, and carbon stocks have only recently received attention, although the impacts of other disturbances such as fires and land-use/land-cover change are much better known. This study, initiated in 2010, aims to increase our understanding of MPB outbreaks and their impacts. We have integrated field-collected data with vegetation simulation models to assess and quantify how long-term patterns of vegetation and carbon stocks have and may change in response to MPB outbreaks and other disturbances.

Colorado↗

Sequence-Stratigraphic Analysis of the Regional Observation Monitoring Program (ROMP) 29A Test Corehole and Its Relation to Carbonate Porosity and Regional Transmissivity in the Floridan Aquifer System, Highlands County, Florida

An analysis was made to describe and interpret the lithology of a part of the Upper Floridan aquifer penetrated by the Regional Observation Monitoring Program (ROMP) 29A test corehole in Highlands County, Florida. This information was integrated into a one-dimensional hydrostratigraphic model that delineates candidate flow zones and confining units in the context of sequence stratigraphy. Results from this test corehole will serve as a starting point to build a robust three-dimensional sequence-stratigraphic framework of the Floridan aquifer system. The ROMP 29A test corehole penetrated the Avon Park Formation, Ocala Limestone, Suwannee Limestone, and Hawthorn Group of middle Eocene to Pliocene age. The part of the Avon Park Formation penetrated in the ROMP 29A test corehole contains two composite depositional sequences. A transgressive systems tract and a highstand systems tract were interpreted for the upper composite sequence; however, only a highstand systems tract was interpreted for the lower composite sequence of the deeper Avon Park stratigraphic section. The composite depositional sequences are composed of at least five high-frequency depositional sequences. These sequences contain high-frequency cycle sets that are an amalgamation of vertically stacked high-frequency cycles. Three types of high-frequency cycles have been identified in the Avon Park Formation: peritidal, shallow subtidal, and deeper subtidal high-frequency cycles. The vertical distribution of carbonate-rock diffuse flow zones within the Avon Park Formation is heterogeneous. Porous vuggy intervals are less than 10 feet, and most are much thinner. The volumetric arrangement of the diffuse flow zones shows that most occur in the highstand systems tract of the lower composite sequence of the Avon Park Formation as compared to the upper composite sequence, which contains both a backstepping transgressive systems tract and a prograding highstand systems tract. Although the porous and permeable layers are not thick, some intervals may exhibit lateral continuity because of their deposition on a broad low-relief ramp. A thick interval of thin vuggy zones and open faults forms thin conduit flow zones mixed with relatively thicker carbonate-rock diffuse flow zones between a depth of 1,070 and 1,244 feet below land surface (bottom of the test corehole). This interval is the most transmissive part of the Avon Park Formation penetrated in the ROMP 29A test corehole and is included in the highstand systems tract of the lower composite sequence. The Ocala Limestone is considered to be a semiconfining unit and contains three depositional sequences penetrated by the ROMP 29A test corehole. Deposited within deeper subtidal depositional cycles, no zones of enhanced porosity and permeability are expected in the Ocala Limestone. A thin erosional remnant of the shallow marine Suwannee Limestone overlies the Ocala Limestone, and permeability seems to be comparatively low because moldic porosity is poorly connected. Rocks that comprise the lower Hawthorn Group, Suwannee Limestone, and Ocala Limestone form a permeable upper zone of the Upper Floridan aquifer, and rocks of the lower Ocala Limestone and Avon Park Formation form a permeable lower zone of the Upper Floridan aquifer. On the basis of a preliminary analysis of transmissivity estimates for wells located north of Lake Okeechobee, spatial relations among groups of relatively high and low transmissivity values within the upper zone are evident. Upper zone transmissivity is generally less than 10,000 feet squared per day in areas located south of a line that extends through Charlotte, Sarasota, DeSoto, Highlands, Polk, Osceola, Okeechobee, and St. Lucie Counties. Transmissivity patterns within the lower zone of the Avon Park Formation cannot be regionally assessed because insufficient data over a wide areal extent have not been compiled.

Open-File Report↗

Fracture trace map and single-well aquifer test results in a carbonate aquifer in Berkeley County, West Virginia

These data contain information on the results of single-well aquifer tests, lineament analysis, and a bedrock geologic map compilation for the low-lying carbonate and shale areas of eastern Berkeley County, West Virginia. Efforts have been initiated by management agencies of Berkeley County in cooperation with the U.S. Geological Survey to further the understanding of the spatial distribution of fractures in the carbonate regions and their correlation with aquifer properties. This report presents transmissivity values from about 200 single-well aquifer tests and a map of fracture-traces determined from aerial photos and field investigations. Transmissivity values were compared to geologic factors possibly affecting its magnitude.

Open-File Report↗

Preliminary Map of Potentially Karstic Carbonate Rocks in the Central and Southern Appalachian States

Karst is a landscape produced by dissolution of rocks and the development of integrated subterranean drainages dominated by the flow of ground water in solutionally enlarged conduits. Karst landscapes typically include cave entrances, sinkholes, blind valleys, losing streams, springs, and large and small-scale solution features on bedrock surfaces. Water-bearing rocks beneath the surface containing solutionally enlarged pores, fractures, or conduits are referred to as karst aquifers. About 40 percent of all ground water extracted in the United States comes from karst aquifers (Karst Waters Institute). Karst means many things to many people. To most cavers and many speleologists, karst means areas containing caves. To engineers, home builders, local governments, and insurance companies, karst is exemplified by the occurrence of sinkholes and subsidence hazard. To hydrologists, well drillers, and environmental consultants, the focus on karst may be more limited to karst aquifers and springs. Precise figures are not available, but ground collapses in karst areas in the United States require hundreds of millions of dollars in repair and mitigation costs each year. Most karst in the United States is formed in either carbonate or evaporite rocks. This map depicts only areas of carbonate rock outcrop, the chief host for karst formation in the eastern United States. The U.S. Geological Survey (USGS), in cooperation with the National Cave and Karst Research Institute (NCKRI), the National Speleological Society (NSS), and various State geological surveys, is working on a new national karst map that will delineate areas of karst and karst-like features nationwide. This product attempts to identify potentially karstic areas of the Appalachian states as defined by the Appalachian Regional Commission (ARC), with the addition of the state of Delaware. This map is labeled preliminary because there is an expectation that it will be revised and updated as part of a new national karst map.

Open-File Report↗

Nutrients, Dissolved Organic Carbon, Color, and Disinfection Byproducts in Base Flow and Stormflow in Streams of the Croton Watershed, Westchester and Putnam Counties, New York, 2000-02

The Croton Watershed is unique among New York City's water-supply watersheds because it has the highest percentages of suburban development (52 percent) and wetland area (6 percent). As the City moves toward filtration of this water supply, there is a need to document water-quality contributions from both human and natural sources within the watershed that can inform watershed-management decisions. Streamwater samples from 24 small (0.1 to 1.5 mi2) subbasins and three wastewater-treatment plants (2000-02) were used to document the seasonal concentrations, values, and formation potentials of selected nutrients, dissolved organic carbon (DOC), color, and disinfection byproducts (DBPs) during stormflow and base-flow conditions. The subbasins were categorized by three types of drainage efficiency and a range of land uses and housing densities. Analyte concentrations in subbasin streams differed in response to the subbasin charateristics. Nutrient concentrations were lowest in undeveloped, forested subbasins that were well drained and increased with all types of development, which included residential, urban commercial/industrial, golf-course, and horse-farm land uses. These concentrations were further modified by subbasin drainage efficiency. DOC, in contrast, was highly dependent on drainage efficiency. Color intensity and DBP formation potentials were, in turn, associated with DOC and thus showed a similar response to drainage efficiency. Every constituent exhibited seasonal changes in concentration. Nutrients. Total (unfiltered) phosphorus (TP), soluble reactive phosphorus (SRP), and nitrate were associated primarily with residential development, urban, golf-course, and horse-farm land uses. Base-flow and stormflow concentrations of the TP, SRP, and nitrate generally increased with increasing housing density. TP and SRP concentrations were nearly an order of magnitude higher in stormflow than in base flow, whereas nitrate concentrations showed little difference between these flow conditions. Organic nitrogen concentrations (calculated as the difference between concentrations of total dissolved N and of all other N species) was the dominant form of nitrogen in undeveloped and moderately to poorly drained subbasins. High TP concentrations in stormflows (800-1,750 ug/L) were associated with well drained and moderately drained residential subbasins with high- and medium-density housing and with the moderately drained golf-course subbasin. Areas with medium to high housing densities favor TP transport because they provide extensive impervious surfaces, storm sewers, and local relief, which together can rapidly route stormwater to streams. SRP concentrations were highest in the same types of subbasins as TP, but also in sewered residential and horse-farm subbasins. The ratio of SRP to TP was typically a smaller in stormflow than in base flow. Base-flow TP and SRP concentrations were highest during the warm-weather months (May to October). The highest nitrate concentrations (3.0-4.5 mg/L) were associated with the urban subbasin and the three well drained, high-density residential subbasins. The two moderately drained lake subbasins and the two poorly drained (colored-water wetland) subbasins had consistently low nitrate concentrations despite low and medium housing densities. Nitrate concentrations were generally highest during the winter months and lowest during the autumn leaf-fall period. Organic N concentrations were highest during the leaf-fall period. Dissolved Organic Carbon. DOC concentration was consistently highest in the two poorly drained (colored-water-wetland) subbasins and lowest in the well drained subbasins. Base-flow DOC concentration increased with decreasing drainage efficiency, except in the well drained sewered subbasin with high-density housing, where slightly elevated DOC concentrations throughout the year may indicate leakage from a nearby sewer main. Seasonal changes in stormflow DOC concentrat

Open-File Report↗

Geologic framework for the national assessment of carbon dioxide storage resources: U.S. Gulf Coast

This report presents 27 storage assessment units (SAUs) within the United States (U.S.) Gulf Coast. The U.S. Gulf Coast contains a regionally extensive, thick succession of clastics, carbonates, salts, and other evaporites that were deposited in a highly cyclic depositional environment that was subjected to a fluctuating siliciclastic sediment supply and transgressive and regressive sea levels. At least nine major depositional packages contain porous strata that are potentially suitable for geologic carbon dioxide (CO 2 ) sequestration within the region. For each SAU identified within these packages, the areal distribution of porous rock that is suitable for geologic CO 2 sequestration is discussed, along with a description of the geologic characteristics that influence the potential CO 2 storage volume and reservoir performance. These characteristics include reservoir depth, gross thickness, net-porous thickness, porosity, permeability, and groundwater salinity. Additionally, a characterization of the overlying regional seal for each SAU is presented. On a case-by-case basis, strategies for estimating the pore volume existing within structurally and (or) stratigraphically closed traps are also presented. Geologic information presented in this report has been employed to calculate potential storage capacities for CO 2 sequestration in the SAUs that are assessed herein, although complete assessment results are not contained in this report.

Alabama, Arkansas, Florida, Georgia, Kentucky, Lou↗

Calculation of hydrocarbon-in-place in gas and gas-condensate reservoirs - Carbon dioxide sequestration

The Energy Independence and Security Act of 2007 (Public Law 110-140) authorized the U.S. Geological Survey (USGS) to conduct a national assessment of geologic storage resources for carbon dioxide (CO 2 ), requiring estimation of hydrocarbon-in-place volumes and formation volume factors for all the oil, gas, and gas-condensate reservoirs within the U.S. sedimentary basins. The procedures to calculate in-place volumes for oil and gas reservoirs have already been presented by Verma and Bird (2005) to help with the USGS assessment of the undiscovered resources in the National Petroleum Reserve, Alaska, but there is no straightforward procedure available for calculating in-place volumes for gas-condensate reservoirs for the carbon sequestration project. The objective of the present study is to propose a simple procedure for calculating the hydrocarbon-in-place volume of a condensate reservoir to help estimate the hydrocarbon pore volume for potential CO 2 sequestration.

Open-File Report↗

Field application of carbon dioxide as a behavioral control method for invasive red swamp crayfish (Procambarus clarkii) in southeastern Michigan water retention ponds

This study evaluated carbon dioxide (CO 2 ) injected into water as a possible behavioral stimulant to enhance capture and removal of invasive red swamp crayfish (RSC, Procambarus clarkii [Girard, 1852]) from a retention pond in southeastern Michigan. Objectives of this study were (1) to determine if target CO 2 concentrations were attainable within the infested pond and (2) to determine if CO 2 treatment was effective to push RSC either towards shorelines or onto dry land, where they could be collected and removed. Carbon dioxide was applied directly into one treatment pond (about [~]2,500 cubic meters) in Novi, Michigan. Two nearby ponds in Livonia, Mich., were used as untreated control ponds. Crayfish removal efficiency was evaluated in all ponds using baited traps and shoreline surveys. Results showed that the CO 2 treatment pond reached its target concentration of greater than (>) 200 milligrams per liter (mg/L) of CO 2 , a benchmark determined from previous laboratory studies, approximately 11 hours after injection started, and maintained concentrations between 200 and 351 mg/L of CO 2 for about 2.5 days. During treatment, some emergent crayfish were observed near influent culverts around the pond, which possibly brought about a behavioral response. However, the number of individuals and crayfish observations were minimal and infrequent. Crayfish continued to be removed throughout CO 2 treatment with baited traps and perimeter surveys, but differences in catch rates between the treatment and control ponds were not apparent and confounded by a temporal decline in catch rates across all ponds. Overall, this study demonstrated that open-water treatment applications with CO 2 are possible, but its effectiveness to enhance RSC removal was unclear because of the limited crayfish observations.

Michigan↗

Selected bibliography on subsidence processes and related engineering problems in carbonate rocks

The Solution Subsidence and Collapse project is a U.S. Geological Survey research activity funded by the Reactor Hazards Research program. The objective of the study is to determine the geologic and hydrologic controls and mechanisms of ground subsidence in soluble rock terranes caused by natural processes and man's activities. The results of the research will be used for the general geologic characterization of proposed and existing nuclear reactor sites in regions underlain by soluble rocks. In addition, the knowledge gained from the study will be applied to defining potential geologic hazards in soluble rock areas where ground subsidence or collapse can occur. The Solution Subsidence and Collapse project is divided into two study units, one looking at subsidence in evaporitic terranes, the other in carbonate terranes. Each of the two geologic environments has its own unique set of conditions that lead to subsidence and, therefore, each warrants its own special study. As part of the subsidence study a selected bibliography covering various topics on ground subsidence in carbonate karst terranes was compiled and is presented here. The entries in the bibliography are placed in five categories: (1) General; (2) Geology, Geomorphology, Hydrology; (3) Caves, Solution Channels; (4) Subsidence, Sinkholes; and (5) Engineering, Land Use, Detection. A separate bibliography on ground subsidence caused by dissolution and removal of salt and other soluble evaporites has been published as a companion reference to this report (Ege, 1979).

Open-File Report↗

Organic carbon content of Devonian shale sequence sampled in drill cuttings from eighteen wells in western Pennsylvania

This report contains results of organic carbon analyses performed by Rinehart Laboratories, Inc., Arvada, Colorado, under contract to the U.S. Geological Survey. The analytical method employs chemical (chromic acid) oxidation of an acid solution containing the rock residue. The detailed analytical specifications are contained in the Rinehart proposal in response to request for proposal 76-79 issued by the U.S. Geological Survey. The samples analyzed were furnished by John W. Hosterman, U.S. Geological Survey, Reston, Virginia, who has performed clay mineralogical analyses on splits of these same samples. In the following tabulation, samples are listed by the depth interval (in feet) over which the drill cuttings were collected. Organic carbon values are single determinations except where two values (duplicate analyses) are given. Each well is identified by county, well name, and API number. An estimate of the shallowest occurrence in the well of some named stratigraphic units has been inserted after the sample depth. These analyses were performed as a part of the U.S. Geological Survey Eastern Black Shales Program, which is being pursued in cooperation with the U.S. Department of Energy under the Eastern Gas Shales Project.

Pennsylvania↗

Particulate organic carbon in San Francisco Bay, California, 1971-1977

The organic-carbon content of suspended particulate matter is determined by wet oxidation and analysis of the resulting CO 2 with an infrared analyzer. Modifications of methods and improved designs of apparatus are presented. Results of particulate organic carbon (POC) analyses from 1971 through 1977 show that concentrations in North San Francisco Bay (estuary) typically decrease from the delta of the Sacramento and San Joaquin rivers to Golden Gate (seaward). Median winter (November through February) concentrations decrease from 85 to 30 µ g-at./L seaward. During March through October, median concentrations are higher and ranges are wider. Concentrations frequently exceed 250 µ g-at./L in the upper estuary. POC concentrations in South San Francisco Bay are highest at the southern reach. POC is more abundant during March through October than during winter, but POC is not as abundant in South San Francisco Bay as it is in the estuary.

California↗

Flow of ground water through fractured carbonate rocks in the Prairie du Chien-Jordan Aquifer, southeastern Minnesota

Contamination of groundwater from point and nonpoint sources (such as landfills, feedlots, agricultural chemicals applied to fields, and septic systems) is a recognized problem in the karst area of southeastern Minnesota. The US Geological Survey, in cooperation with the Minnesota Department of Natural Resources and the Legislative Commission on Minnesota Resources, Began a study in October 1987 to improve the understanding of local groundwater flow through karst terrain in southeastern Minnesota. The objectives of the study are to: (1) describe the orientations of systematic rock fractures and solution channels of the Prairie du Chien Group of Ordovician-age carbonate rocks in southeastern Minnesota, and, if possible, to define the principal and minor axes of these orientations; and (2) evaluate the effect of fractures and solution channels in the Prairie du Chien Group on the local flow of groundwater. Groundwater in the Upper Carbonate aquifer regionally flows toward the periphery of the aquifer and locally flows into streams and bedrock valleys. The hydraulic gradient in this aquifer generally is greatest near areas of groundwater seepage to streams. Regional groundwater flow in the Prairie du Chien-Jordan aquifer generally is to the south and east in much of Fillmore and Houston Counties and in the southern parts of Olmsted and Winona Counties. Groundwater seepage to selected streams was evaluated by current-meter measurements of downstream gains or losses of streamflow and by an experimental approach based on radon activity in streams. The activity of radon in groundwater ranges from two to four orders of magnitude greater than the activity in surface water; therefore, groundwater seepage to streams generally increases the in-stream radon activity.

Minnesota↗

Ground-water resources of Cambrian and Ordovician carbonate rocks in the valley and ridge physiographic province of Pennsylvania

About 43 million gallons per day of ground water was used in 1985 by the 150,000 people living in the 10 valleys of central Pennsylvania that are underlain by Cambrian and Ordovician carbonate rocks. Noticeable effects on water levels from withdrawals occur in the vicinity of the Borough of State College where an average of 8.1 million gallons per day is pumped. The carbonate aquifer system is heterogeneous and anisotropic parallel to the regional strike. The Nittany and Gatesburg Formations are the most prolific sources of water and will yield 1,000 gallons per minute or more to properly located and constructed wells. The Coburn through Nealmont Formations are the poorest sources of water but wells in these rocks will yield about 50 gallons per minute. Of the 42 large perennial springs identified, 25 have flows that commonly exceed 1,000 gallons per minute, and flows of 3 of the largest springs at times exceed 10,000 gallons per minute. Water budgets for Kishacoquillas and Spring Creeks, which are representative of all the valleys, indicate that an annual average of 0.62 and 0.80 million gallons per day per square mile, respectively, are available for water supply. Nitrate, chiefly from agricultural sources, averages from 3.3 to 5.9 milligrams per liter in ground water from individual valleys. Triazine herbicides at extremely low concentrations were present in 11 of 20 well and spring water samples.

Open-File Report↗

A compilation of sulfur dioxide and carbon dioxide emission-rate data from Mount St. Helens during 1980-88

Airborne monitoring of Mount St. Helens by the USGS began inMay 1980 for sulfur dioxide emissions and in July 1980 forcarbon dioxide emissions. A correlation spectrometer, orCOSPEC, was used to measure sulfur dioxide in Mount St.Helens' plume. The upward-looking COSPEC was mounted in afixed-wing aircraft and flown below and at right angles to theplume. Typically, three to six traverses were made underneaththe plume to determine the SO2 burden (concentration xpathlength) within a cross-section of the plume. Knowing theburden along with the plume width and plume velocity (assumedto be the same as ambient wind speed), we could then calculatethe emission rate of SO2. The use of correlation spectroscopyfor determining the sulfur dioxide output of volcanoes is wellestablished and the technique has been discussed in detail bya number of investigators (Malinconico, 1979; Casadevall andothers, 1981; Stoiber and others, 1983).Carbon dioxide in the Mount St. Helens plume was measured byan infrared spectrometer tuned to the 4.26 um CO2 absorptionband. An external sample tube was attached to the fuselage ofa twin-engine aircraft to deliver outside air to the gas cellof the spectrometer. The aircraft was then flown at severaldifferent elevations through the plume at right angles toplume trajectory to define plume area and carbon dioxideconcentration in a vertical cross-section of the plume. Thesetwo parameters along with the density of CO2 for the altitudeof the plume and the plume velocity (assumed as above to beequal to ambient wind speed) were then used to calculate theCO2 emission rate.

Open-File Report↗

Use of stable isotopes of carbon, nitrogen, and sulfer to identify sources of nitrogen in surface waters in the Lower Susquehanna River basin, Pennsylvania

Stable isotopes of carbon (C), nitrogen (N), and sulfur (S) in nitrogen sources and nearby samples of topsoil, subsoil, runoff water, and stream water were measured to evaluate the feasibility of using isotopic data to identify nitrogen sources in stream water from forested, agricultural, or suburban land-use areas. Chemical and isotopic compositions were measured for six N-source types consisting of rain water, forest-leaf litter, synthetic fertilizer, farm-animal manure, municipal-sewage effluent and sludge, and septic-tank effluent and sludge. Compositions of topsoil, subsoil, runoff water, and stream water were measured to evaluate changes in compositions of transported N-containing materials near the N source. Animal manure, human waste (sewage plus septic), and forest-leaf litter can be distinguished on the basis of C; however, most N-sources can not be distinguished on the basis of N and S, owing to wide ranges of compositions and overlap among different N-source types. Although values of N for soil and runoff-water samples are qualitatively similar to those of the applied N source, values of C and S for runoff-water and stream-water samples appear to reflect the compositions of relatively large reservoirs of the elements in soil organic matter and minerals, respectively, and not the composition of the applied N source. Because of incomplete chemical transfor- mations, the ratio of organic carbon to total nitrogen for particulates in runoff or stream waters generally is lower than that for associated, nearby soils, and isotopic compositions commonly differ between particulate and dissolved fractions in the water.

Open-File Report↗

Data compilation, synthesis, and calculations used for organic-carbon storage and inventory estimates for mineral soils of the Mississippi River Basin

U.S. Geological Survey investigations of environmental controls on carbon cycling in soils and sediments of the Mississippi River Basin (MRB), an area of 3.3 x 106 square kilometers (km2), have produced an assessment tool for estimating the storage and inventory of soil organic carbon (SOC) by using soil-characterization data from Federal, State, academic, and literature sources. The methodology is based on the linkage of site-specific SOC data (pedon data) to the soil-association map units of the U.S. Department of Agriculture State Soil Geographic (STATSGO) and Soil Survey Geographic (SSURGO) digital soil databases in a geographic information system. The collective pedon database assembled from individual sources presently contains 7,321 pedon records representing 2,581 soil series. SOC storage, in kilograms per square meter (kg/m2), is calculated for each pedon at standard depth intervals from 0 to 10, 10 to 20, 20 to 50, and 50 to 100 centimeters. The site-specific storage estimates are then regionalized to produce national-scale (STATSGO) and county-scale (SSURGO) maps of SOC to a specified depth. Based on this methodology, the mean SOC storage for the top meter of mineral soil in the MRB is approximately 10 kg/m2, and the total inventory is approximately 32.3 Pg (1 petagram = 109 metric tons). This inventory is from 2.5 to 3 percent of the estimated global mineral SOC pool.

Professional Paper↗