Geology topics

Sharon E. Kroening

Publications and source records attributed to Sharon E. Kroening.

10 recordsLinked to original sources

USGS2014

Contaminants of emerging concern in ambient groundwater in urbanized areas of Minnesota, 2009-12

A study of contaminants of emerging concern (CECs) in ambient groundwater in urbanized areas of Minnesota was completed by the U.S. Geological Survey in cooperation with the Minnesota Pollution Control Agency. For this study, water samples were collected from November 2009 through June 2012 from 118 wells located in different land-use settings. The sampled wells primarily were screened in vulnerable sand and gravel aquifers (surficial and buried glacial aquifers) or vulnerable bedrock aquifers such as the Prairie du Chien-Jordan aquifer. Sampled well depths ranged from 9 to 285 feet below land surface. Water samples were collected by Minnesota Pollution Control Agency staff. The water samples were analyzed at U.S. Geological Survey laboratories for steroidal hormones, human-use pharmaceutical compounds, human- and animal-use antibiotics, and a broad suite of organic chemicals associated with wastewater. Reported detections were censored and not counted as detections in the data analyses if the chemical was detected in a laboratory or field blank at a similar concentration. During this study, 38 out of 127 CECs analyzed were detected among all water samples collected. Three of the detected CECs, however, were analyzed using two different analytical methods, so 35 distinct chemicals were detected. The number of detections of CECs in individual water samples ranged from 0 to 10. The three wells in proximity to landfills had the most CEC detections. One or more CECs were detected in a total of 43 samples (35 percent); no CECs were detected in 80 samples. Of the 127 CECs included for analysis in this study, 28 have established enforceable or non-enforceable health-based water-quality standards or benchmarks. Fourteen of the 35 chemicals detected in this study have established water-quality standards, whereas 21 of the chemicals detected have no established standard or benchmark. All detections in this study were less than established health-based water-quality standards, although p-cresol was detected at a concentration nearing a health-based water quality standard. Four of the six most frequently detected chemicals—azithromycin, diphenhydramine, tributyl phosphate, and lincomycin—have no health-based water-quality standards or benchmarks. The antibiotic sulfamethoxazole was the most frequently detected CEC, detected in a total of 14 of 123 samples (11.4 percent) by one or both analytical methods that include sulfamethoxazole as an analyte. Most (11 of 14, or 79 percent) of the detections of sulfamethoxazole were in samples from domestic wells or monitoring wells located in areas where septic systems or potentially leaking centralized sewers are prevalent. The chemical N,N-Diethyl-meta-toluamide (DEET) was detected at the highest concentration of any CEC, at 7.9 micrograms per liter. Bisphenol A was detected second most frequently of all chemicals. DEET and Bisphenol A were detected most frequently in wells in proximity to closed landfills. Samples from bedrock wells, most of which are drinking water wells that are deeper than glacial wells, had a higher percentage of wells with CEC detections compared to samples from wells completed in glacial aquifers. The higher dissolved oxygen concentrations and lower specific conductance for the bedrock wells sampled indicate shorter duration flow paths from the land surface to these wells than for wells completed in glacial aquifers.

Minnesota↗

USGS2009

Water quality and evaluation of pesticides in lakes in the Ridge Citrus region of central Florida

Water chemistry, including major inorganic constituents, nutrients, and pesticide compounds, was compared between seven lakes surrounded by citrus agriculture and an undeveloped lake on the Lake Wales Ridge (herein referred to as the Ridge) in central Florida. The region has been recognized for its vulnerability to the leaching of agricultural chemicals into the subsurface due to factors including soils, climate, and land use. About 40 percent of Florida's citrus cultivation occurs in 'ridge citrus' areas characterized by sandy well drained soils, with the remainder in 'flatwoods citrus' characterized by high water tables and poorly drained soils. The lakes on the Ridge are typically flow-through lakes that exchange water with adjacent and underlying aquifer systems. This study is the first to evaluate the occurrence of pesticides in lakes on the Ridge, and also represents one of the first monitoring efforts nationally to focus on regional-scale assessment of current-use pesticides in small- to moderate-sized lakes (5 to 393 acres). The samples were collected between December 2003 and September 2005. The lakes in citrus areas contained elevated concentrations of major inorganic constituents (including alkalinity, total dissolved solids, calcium, magnesium, sodium, potassium, chloride, and sulfate), total nitrogen, pH, and pesticides compared to the undeveloped lake. Nitrate (as N) and total nitrogen concentrations were typically elevated in the citrus lakes, with maximum values of 4.70 and 5.19 mg/L (milligrams per liter), respectively. Elevated concentrations of potassium, nitrate, and other inorganic constituents in the citrus lakes likely reflect inputs from the surficial ground-water system that originated predominantly from agricultural fertilizers, soil amendments, and inorganic pesticides. A total of 20 pesticide compounds were detected in the lakes, of which 12 compounds exceeded the standardized reporting level of 0.06 ug/L (microgram per liter). Those most frequently detected above the 0.06-ug/L level were aldicarb sulfoxide, diuron, simazine degradates hydroxysimazine and didealkylatrazine (DDA), bromacil, norflurazon, and demethyl norflurazon which occurred at detection rates ranging from 25 to 86 percent of samples, respectively. Typically, pesticide concentrations in the lake samples were less than 1 microgram per liter. The number of targeted pesticide compounds detected per lake in the citrus areas ranged from 9 to 14 compared to 3 compounds detected at trace levels in the undeveloped lake. Consistent detections of parents and degradates in quarterly samples indicated the presence of pesticide compounds in the lakes many months or years (for example, bromacil) after their application, signaling the persistence of some pesticide compounds in the lakes and/or ground-water systems. Pesticide degradate concentrations frequently exceeded parent concentrations in the lakes. This study was the first in the Ridge citrus region to analyze for glyphosate - widely used in citrus - and its degradate aminomethylphosphonic acid (AMPA), neither of which were detected, as well as a number of triazine degradates, including hydroxysimazine, which were detected. The lake pesticide concentrations did not exceed current Federal aquatic-life benchmarks, available for 10 of the 20 detected pesticide compounds. Limited occurrences of bromacil, diuron, or norflurazon concentrations were within about 10 to 90 percent of benchmark guidelines for acute effects on nonvascular aquatic plants in one or two of the lakes. The lake pesticide concentrations for several targeted pesticides were relatively high compared to corresponding national stream-water percentiles, which is consistent with this region's vulnerability for pesticide leaching into water resources. Several factors were evaluated to gain insight into the processes controlling pesticide transport and fate, and to assess their utility for estimating th

Florida↗

USGS2008

Assessment of Water-Quality Monitoring and a Proposed Water-Quality Monitoring Network for the Mosquito Lagoon Basin, East-Central Florida

Surface- and ground-water quality data from the Mosquito Lagoon Basin were compiled and analyzed to: (1) describe historical and current monitoring in the basin, (2) summarize surface- and ground-water quality conditions with an emphasis on identifying areas that require additional monitoring, and (3) develop a water-quality monitoring network to meet the goals of Canaveral National Seashore (a National Park) and to fill gaps in current monitoring. Water-quality data were compiled from the U.S. Environmental Protection Agency's STORET system, the U.S. Geological Survey's National Water Information System, or from the agency which collected the data. Most water-quality monitoring focused on assessing conditions in Mosquito Lagoon. Significant spatial and/or seasonal variations in water-quality constituents in the lagoon were quantified for pH values, fecal coliform bacteria counts, and concentrations of dissolved oxygen, total nitrogen, total phosphorus, chlorophyll-a, and total suspended solids. Trace element, pesticide, and ground-water-quality data were more limited. Organochlorine insecticides were the major class of pesticides analyzed. A surface- and ground-water-quality monitoring network was designed for the Mosquito Lagoon Basin which emphasizes: (1) analysis of compounds indicative of human activities, including pesticides and other trace organic compounds present in domestic and industrial waste; (2) greater data collection in the southern part of Mosquito Lagoon where spatial variations in water-quality constituents were quantified; and (3) additional ground-water-quality data collection in the surficial aquifer system and Upper Floridan aquifer. Surface-water-quality data collected as part of this network would include a fixed-station monitoring network of eight sites in the southern part of the basin, including a canal draining Oak Hill. Ground-water quality monitoring should be done routinely at about 20 wells in the surficial aquifer system and Upper Floridan aquifer, distributed between developed and undeveloped parts of the basin. Water samples collected should be analyzed for a wide range of constituents, including physical properties, nutrients, suspended sediment, and constituents associated with increased urban development such as pesticides, other trace organic compounds associated with domestic and industrial waste, and trace elements.

Scientific Investigations Report↗

USGS2007

Aquatic Community, Hydrologic, and Water-Quality Data for Apopka, Bugg, Rock, and Wekiva Springs, Central Florida, 1931-2006

This report summarizes aquatic community, hydrologic, and water-quality data collected or compiled by the U.S. Geological Survey (USGS) for Apopka, Bugg, Rock, and Wekiva springs from October 1, 2005 to September 30, 2006. Aquatic community data are summarized for quarterly collections of benthic macroinvertebrates, and fishes collected during one sampling event per spring. Hydrologic data for each spring were compiled from the USGS, St. Johns River Water Management District, and a private landowner. Water-quality data collected by the USGS consisted of quarterly psysicochemical, chlorophyll-a, and pheophytin-a measurements; water-quality data were collected on the same days that the benthic macroinvertebrates were sampled.

Open-File Report↗

USGS2007

Hydrology of Polk County, Florida

Local water managers usually rely on information produced at the State and regional scale to make water-resource management decisions. Current assessments of hydrologic and water-quality conditions in Polk County, Florida, commonly end at the boundaries of two water management districts (South Florida Water Management District and the Southwest Florida Water Management District), which makes it difficult for managers to determine conditions throughout the county. The last comprehensive water-resources assessment of Polk County was published almost 40 years ago. To address the need for current countywide information, the U.S. Geological Survey began a 3?-year study in 2002 to update information about hydrologic and water-quality conditions in Polk County and identify changes that have occurred. Ground-water use in Polk County has decreased substantially since 1965. In 1965, total ground-water withdrawals in the county were about 350 million gallons per day. In 2002, withdrawals totaled about 285 million gallons per day, of which nearly 95 percent was from the Floridan aquifer system. Water-conservation practices mainly related to the phosphate-mining industry as well as the decrease in the number of mines in operation in Polk County have reduced total water use by about 65 million gallons per day since 1965. Polk County is underlain by three principal hydrogeologic units. The uppermost water-bearing unit is the surficial aquifer system, which is unconfined and composed primarily of clastic deposits. The surficial aquifer system is underlain by the intermediate confining unit, which grades into the intermediate aquifer system and consists of up to two water-bearing zones composed of interbedded clastic and carbonate rocks. The lowermost hydrogeologic unit is the Floridan aquifer system. The Floridan aquifer system, a thick sequence of permeable limestone and dolostone, consists of the Upper Floridan aquifer, a middle semiconfining unit, a middle confining unit, and the Lower Floridan aquifer. The Upper Floridan aquifer provides most of the water required to meet demand in Polk County. Data from about 300 geophysical and geologic logs were used to construct hydrogeologic maps showing the tops and thicknesses of the aquifers and confining units within Polk County. Thickness of the surficial aquifer system ranges from several feet thick or less in the extreme northwestern part of the county and along parts of the Peace River south of Bartow to more than 200 feet along the southern part of the Lake Wales Ridge in eastern Polk County. Thickness of the intermediate aquifer system/intermediate confining unit is highly variable throughout the county because of past erosional processes and sinkhole formation. Thickness of the unit ranges from less than 25 feet in the extreme northwestern part of the county to more than 300 feet in southwestern Polk County. The altitude of the top of the Upper Floridan aquifer in the county ranges from about 50 feet above National Geodetic Vertical Datum of 1929 (NGVD 29) in the northwestern part to more than 250 feet below NGVD 29 in the southern part. Water levels in the Upper Floridan aquifer fluctuate seasonally, increasing during the wet season (June through September) and decreasing during the rest of the year. Water levels in the Upper Floridan aquifer also can change from year to year, depending on such factors as pumpage and climatic variations. In the southwestern part of the county, fluctuations in water use related to phosphate mining have had a major impact on ground-water levels. Hydrographs of selected wells in southwestern Polk County show a general decline in water levels that ended in the mid-1970s. This water-level decline coincides with an increase in water use associated with phosphate mining. A substantial increase in water levels that began in the mid-1970s coincides with a period of decreasing water use in the county. Despite reductions in water use since 1970, howev

Scientific Investigations Report↗

USGS2004

Streamflow and water-quality characteristics at selected sites of the St. Johns River in central Florida, 1933 to 2002

To meet water-supply needs in central Florida for 2020, the St. Johns River is being considered as a source of water supply to augment ground water from the Floridan aquifer system. Current (2004) information on streamflow and water-quality characteristics of the St. Johns River in east-central Florida is needed by water resources planners to assess the feasibility of using the river as an alternate source of water supply and to design water treatment facilities. To address this need, streamflow and water quality of the 90-mile-long middle reach of the St. Johns River, Florida, from downstream of Lake Poinsett to near DeLand, were characterized by using retrospective (1991-99) and recently collected data (2000-02). Streamflow characteristics were determined by using data from water years 1933-2000. Water-quality characteristics were described using data from 1991-99 at 15 sites on the St. Johns River and 1 site each near the mouths of the Econlockhatchee and Wekiva Rivers. Data were augmented with biweekly water-quality data and continuous physical properties data at four St. Johns River sites and quarterly data from sites on the Wekiva River, Blackwater Creek, and downstream of Blue Springs from 2000-02. Water-quality constituents described were limited to information on physical properties, major ions and other inorganic constituents, nutrients, organic carbon, suspended solids, and phytoplankton chlorophyll-a. The occurrence of antibiotics, human prescription and nonprescription drugs, pesticides, and a suite of organic constituents, which may indicate domestic or industrial waste, were described at two St. Johns River sites using limited data collected in water years 2002-03. The occurrence of these same constituents in water from a pilot water treatment facility on Lake Monroe also was described using data from one sampling event conducted in March 2003. Dissolved oxygen concentration and water pH values in the St. Johns River were significantly lower during high-flow conditions than during low-flow conditions. Low dissolved oxygen concentrations may have resulted from the input of water from marsh areas or the subsequent decomposition of organic matter transported to the river during high-flow events. Low water pH values during high-flow conditions likely resulted from the increased dissolved organic carbon concentrations in the river. Concentrations of total dissolved solids and other inorganic constituents in the St. Johns River were inversely related with streamflow. Most major ion concentrations, total dissolved solids concentrations, and specific conductance values varied substantially at the Christmas, Sanford, and DeLand sites during low-flow periods in 2000-01 probably reflecting wind and tidal effects. Sulfide concentrations as high as 6 milligrams per liter (mg/L) were measured in the St. Johns River during high-flow periods. Increased sulfide concentrations likely resulted from the decomposition of organic matter or the reduction of sulfate. Bromide concentrations as high as 17 mg/L were measured at the most upstream site on the St. Johns River during 2000-02. Temporal variations in bromide were characterized by sharp peaks in concentration during low-flow periods. Peaks in bromide concentrations tended to coincide with peaks in chloride concentrations because the likely source of both constituents is ground water affected by relict seawater. Median dissolved organic carbon concentrations ranged from 15 to 26 mg/L during 2000-02, and concentrations as high as 42 mg/L were measured. Water color values and dissolved organic carbon concentrations generally were significantly greater during high-flow conditions than during low-flow conditions. Specific ultraviolet light absorbance data indicated the organic carbon during high-flow events was more aromatic in composition and likely originated from terrestrially derived sources compared to organic carbon in the river during other times of the year. D

Scientific Investigations Report↗

USGS1999

Fecal coliform and Escherichia coli bacteria in the St. Croix National Scenic Riverway, Summer 1999

Fecal coliform and Escherichia coli ( E. coli ) concentrations were determined in the St. Croix National Scenic Riverway to assess whether pathogenic organisms pose a potential problem for recreational use. Samples were collected from May through September 1999 at 22 locations on the St. Croix and Namekagon Rivers. No concentrations exceeded water-quality criteria or standards set by the U.S. Environmental Protection Agency or the states of Minnesota and Wisconsin. Maximum fecal coliform and E. coli concentrations were measured in the St. Croix River at St. Croix Falls, Wisconsin. Median fecal coliform and E. coli concentrations were greater in the St. Croix River near Woodland Corner, Wisconsin, and at Marine on St. Croix, Minnesota than at other locations sampled. There were no consistent short-term variations in fecal coliform or E. coli concentrations during the summer period or any significant relations between concentrations and stream discharge, based on these results.

Minnesota, Wisconsin↗

USGS1998

Nutrient sources within the Upper Mississippi River Basin, Minnesota and Wisconsin, 1991-93

The amount of nutrients contained in fertilizer, livestock manure, municipal wastewater, atmospheric deposition, and legume residues were quantified in each of the major drainage basins within the Upper Mississippi River Basin study unit (fig. 1) as part of the U.S. Geological Survey's National Water-Quality Assessment Program. These sources of nutrients may potentially affect surface- and ground-water quality, so knowledge about the relative importance of each source may assist in the management of surface and ground waters within the study unit. The relative importance of each nutrient source was expected to vary among each of the four drainage basins due to differences in land use across the study unit. Fertilizer and livestock manure were potentially large sources of nitrogen and phosphorus in each of the four drainage basins. However, nitrogen in legume residues was a more important source in the Upper Mississippi, St. Croix, and Lower Mississippi River Basins because hay comprised a larger part of the total acreage of crops grown in these basins. Atmospheric deposition comprised a larger percentage of the nitrogen sources in the St. Croix River Basin compared to the other three drainage basins probably because amounts of the other sources are relatively low. Nitrogen and phosphorus yields in streams were greatest in the Lower Mississippi River Basin and the Minnesota River Basin, where amounts of nonpoint sources of these constituents also were the greatest per square mile.

Minnesota, Wisconsin↗

USGS1997

Variability of nutrients in streams in part of the Upper Mississippi River Basin, Minnesota and Wisconsin

Physical conditions differ among the Mississippi River and its major tributaries in Minnesota and Wisconsin. Analysis of the environmental framework of the basin and analysis of historical water-quality information by the National Water-Quality Assessment (NAWQA) Program shows that nutrients (nitrogen and phosphorus) in streams in the Upper Mississippi River Basin are influenced primarily by land use. In the Mississippi River, nutrient concentrations were greater downstream of the Minnesota River and major wastewater discharge points in the Twin Cities Metropolitan Area (TCMA). Stream loads of nutrients (the amount of the constituent carried past a point on a stream during a given period of time) also increased downstream of the Minnesota River and major wastewater discharge points in the TCMA.

Minnesota, Wisconsin↗

USGS1997

Water-quality assessment of part of the upper Mississippi River Basin, Minnesota and Wisconsin — Nitrogen and phosphorus in streams, streambed sediment, and ground water, 1971-94

Nitrogen and phosphorus in streams, streambed sediment, and ground water were summarized using data from Federal, state, and local agencies as part of an analysis of historical water-quality data for the Upper Mississippi River Basin study unit of the U.S. Geological Survey's National Water-Quality Assessment Program. The Upper Mississippi River Basin study unit encompasses the drainage of the Mississippi River from the source to the outlet of Lake Pepin. This report focuses on a 19,500-square-mile study area in the eastern part of the study unit. The study area included the part of the Upper Mississippi River Basin from Royalton, Minnesota, to the outlet of Lake Pepin, located near Red Wing, Minnesota; the Minnesota River Basin from Jordan, Minnesota, to the confluence with the Mississippi River; and the entire drainage basins of the St. Croix, Cannon, and Vermillion Rivers. The Twin Cities metropolitan area, with a population of approximately 2.3 million people, is located in the south-central part of the study area. Fertilizers and livestock manure were the greatest sources of nitrogen and phosphorus applied to the land surface of the study unit. Approximately 60 percent of the fertilizer was applied to the Minnesota River Basin, which drains agricultural areas in the southern and western parts of the study unit. Concentrations of total nitrite plus nitrate nitrogen, total nitrogen, and total phosphorus in streams, generally were greatest in the tributaries to the Mississippi River draining agricultural areas in the western and southern part of the study area. Concentrations of these constituents generally were least in tributaries draining forested land. The greatest total nitrite plus nitrate nitrogen concentrations generally occurred during the spring and summer in streams draining agricultural areas and in the winter in streams draining forested areas. Total phosphorus concentrations generally were greatest in the spring and summer for all streams. Total nitrite plus nitrate nitrogen, total nitrogen, and total phosphorus concentrations in the Mississippi River increased substantially downstream from the Minnesota River and downstream from wastewater discharges in the Twin Cities metropolitan area. Total ammonia and dissolved orthophosphate concentrations generally were greatest at sites on the Mississippi and Minnesota Rivers downstream from wastewater discharges from the Twin Cities metropolitan area. Total nitrite plus nitrate nitrogen concentrations in streams generally were less than the Maximum Contaminant Level of 10 mg/L (as nitrogen) established by the U.S. Environmental Protection Agency. Total phosphorus concentrations in streams generally were greater than the 0.1 mg/L concentration recommended by the U.S. Environmental Protection Agency at sites located in agricultural areas and on the Mississippi River downstream from its confluence with the Minnesota River. Phosphorus and nitrogen yields were greatest in watersheds primarily draining agricultural land. The majority of the nitrogen and phosphorus loading to the Mississippi River was from the Minnesota River. In the Minnesota River, the nitrogen load primarily was total nitrite plus nitrate nitrogen. Despite increases in fertilizer usage during 1982-91, most stream sites outside of the Twin Cities metropolitan area had no temporal trends in total nitrite plus nitrate nitrogen, total phosphorus, or dissolved orthophosphate concentrations for water years 1984-93. Most sites had a decrease in total ammonia nitrogen concentrations, possibly a result of improvements in wastewater treatment. In the Twin Cities metropolitan area, decreases in total ammonia concentrations in the Mississippi and Minnesota Rivers coincided with increases in total nitrite plus nitrate nitrogen concentrations, probably a result of wastewater treatment plants initiating nitrification processes. Nitrite plus nitrate nitrogen concentrations in ground water reflect land uses and hydrogeologic settings of major aquifers in the study area. Unconfined sand and gravel, buried sand and gravel, and the Prairie du Chien-Jordan were the aquifers most frequently sampled for nitrite plus nitrate nitrogen because they are the principal sources of ground water in the study area. The greatest nitrite plus nitrate nitrogen concentrations reported by Federal and state agencies, some exceeding the U.S. Environmental Protection Agency's Maximum Contaminant level of 10 mg/L by a factor of four, were in water from shallow wells in agricultural and mixed forested and agricultural areas. Water sampled from buried sand and gravel aquifers, which are more shielded from substances leaching from the land surface by layers of clay or till, generally had lower nitrite plus nitrate nitrogen concentrations than water from unconfined sand and gravel aquifers. Nitrite plus nitrate nitrogen concentrations in water samples from the Prairie du Chien-Jordan aquifer were greatest in the Wisconsin part of the study area and in the vicinity of the Cannon River, where the aquifer is commonly unconfined, exposed at land surface, and overlain by agricultural or by mixed forested and agricultural land covers. Dissolved phosphorus concentrations in ground water in the study area generally were near detection limits of 0.01 mg/L or lower, indicating that surface-water eutrophication from phosphorus may be more likely to occur from overland runoff of phosphorus compounds and from direct discharges of treated wastewater than from ground-water base flow. The greatest concentrations of dissolved phosphorus in ground water generally were detected in water samples from wells in urban portions of the study area.

Minnesota, Wisconsin↗