Geology topics

Research about Ozark Plateaus study unit

Source-linked reports with geographic coverage including Ozark Plateaus study unit.

4 recordsLinked to original sources

USGS1998

Water-quality assessment of the Ozark Plateaus study unit, Arkansas, Kansas, Missouri, and Oklahoma — Nutrients, bacteria, organic carbon, and suspended sediment in surface water, 1993-95

Nutrient, bacteria, organic carbon, and suspended- sediment samples were collected from 1993-95 at 43 surface-water-quality sampling sites within the Ozark Plateaus National Water- Quality Assessment Program study unit. Most surface-water-quality sites have small or medium drainage basins, near-homogenous land uses (primarily agricultural or forest), and are located predominantly in the Springfield and Salem Plateaus. The water-quality data were analyzed using selected descriptive and statistical methods to determine factors affecting occurrence in streams in the study unit. Nitrogen and phosphorus fertilizer use increased in the Ozark Plateaus study unit for the period 1965-85, but the application rates are well below the national median. Fertilizer use differed substantially among the major river basins and physiographic areas in the study unit. Livestock and poultry waste is a major source of nutrient loading in parts of the study unit. The quantity of nitrogen and phosphorus from livestock and poultry wastes differed substantially among the river basins of the study unit's sampling network. Eighty six municipal sewage-treatment plants in the study unit have effluents of 0.5 million gallons per day or more (for the years 1985-91). Statistically significant differences existed in surface-water quality that can be attributed to land use, physiography, and drainage basin size. Dissolved nitrite plus nitrate, total phosphorus, fecal coliform bacteria, and dissolved organic carbon concentrations generally were larger at sites associated with agricultural basins than at sites associated with forested basins. A large difference in dissolved nitrite plus nitrate concentrations occurred between streams draining basins with agricultural land use in the Springfield and Salem Plateaus. Streams draining both small and medium agricultural basins in the Springfield Plateau had much larger concentrations than their counterparts in the Salem Plateau. Drainage basin size was not a significant factor in affecting total phosphorus, fecal coliform bacteria, or dissolved organic carbon concentrations. Suspended-sediment concentrations generally were small and indicative of the clear water in streams in the Ozark Plateaus. A comparison of the dissolved nitrite plus nitrate, total phosphorus, and fecal coliform data collected at the fixed and synoptic sites indicates that generally the data for streams draining basins of similar physiography, land-use setting, and drainage basin size group together. Many of the variations are most likely the result of differences in percent agricultural land use between the sites being compared or are discharge related. The relation of dissolved nitrite plus nitrate, total phosphorus, and fecal coliform concentration to percent agricultural land use has a strong positive 2 Water-Quality Assessment-Nutrients, Bacteria, Organic Carbon, and Suspended Sediment in Surface Water, 1993-95 correlation, with percent agricultural land use accounting for between 42 and 60 percent of the variation in the observed concentrations.

Arkansas, Kansas, Missouri, Oklahoma↗

USGS1997

Nutrients and pesticides in ground water of the Ozark Plateaus in Arkansas, Kansas, Missouri, and Oklahoma

A total of 229 ground-water samples were collected from 215 sites as part of the Ozark Plateaus study unit of the National Water-Quality Assessment Program. These samples were collected from 1993 through 1995 using a network of springs and wells with three scale-dependent components. The first component, the study-unit survey, consisted of 99 randomly selected springs and domestic wells in the Springfield Plateau and Ozark aquifers. The second component, two land-use studies, consisted of 42 springs and domestic wells in a poultry-dominated agricultural area and 40 springs and domestic wells in a cattle-dominated agricultural area overlying the Springfield Plateau aquifer. The third component, the small-watershed study, consisted of 4 springs, 18 domestic wells, and 11 monitoring wells in a small basin within the poultry land-use study area. Samples were analyzed for major ions, nutrients, dissolved organic carbon, methylene blue active substances, tritium, and 88 pesticides and metabolites.The water-quality data from these samples were analyzed with descriptive and statistical methods. Nitrite plus nitrate, which was detected more often and in greater concentrations than any of the other nutrients, ranged from less than 0.05 to 25 milligrams per liter as nitrogen. Nitrite plus nitrate concentrations positively correlated to percent agricultural land use around each site. Median nitrite plus nitrate concentrations generally were greater in samples from springs than in samples from wells. Concentrations of nitrite, ammonia, and ammonia plus organic nitrogen were also affected by land use and also by concentrations of dissolved oxygen in the ground water. Concentrations of phosphorus and orthophosphate probably were affected by land use and also by phosphorus solubility. Pesticides were detected in 80 of 229 samples from 73 of 215 sites. A total of 20 pesticides were detected with a maximum of 5 pesticides detected in any 1 sample. The most commonly detected pesticides were tebuthiuron, atrazine, prometon, desethylatrazine, and simazine. Maximum concentrations ranged from 0.003 to 1.0 microgram per liter. The occurrence and distribution of pesticides were related to land use. Percent agricultural land use was greater for samples with pesticides detected than for samples with no pesticides detected. Pesticides were detected more often in samples from springs than in samples from wells. The occurrence of pesticides also was related to seasonality and chemical characteristics, such as solubility and persistence, of the compounds.

Arkansas, Kansas, Missouri, Oklahoma↗

USGS1997

Water-quality assessment of the Ozark Plateaus study unit, Arkansas, Kansas, Missouri, and Oklahoma: Organic compounds in surface water, bed sediment, and biological tissue, 1992-95

Organic-compound samples, including pesticides and semi-volatiles, were collected from 1992-95 at 43 surface-water and 27 bed-sediment and biological-tissue sampling sites within the Ozark Plateaus National Water-Quality Assessment Program study unit. Most surface-water, bed-sediment, and biological-tissue sites have drainage basins predominantly in the Springfield and Salem Plateaus. At most surface-water sampling sites, one to three pesticide samples were collected in the spring and early summer of 1994 and 1995; two sites had additional samples collected either weekly, biweekly, or monthly from February 1994 through December 1994. At most bed-sediment and biological-tissue sampling sites, a single organic-compounds sample was collected. Agricultural pesticide use was approximately 4.9 million pounds of active ingredients per year from 1987-91 in the study unit and was generally greatest in the Springfield and Salem Plateaus pasturelands and in the Osage Plains and Mississippi Alluvial Plain cropland areas. The most frequently applied pesticide in the study unit was 2,4-D. Atrazine was the second most frequently applied pesticide. Corn, pasture, rice, sorghum, and soybeans received approximately 85 percent of the pesticides applied within the study unit. The highest pesticide application rate occurred on these crops in the Mississippi Alluvial and Osage Plains. Pastureland was the crop type that received the greatest amount of pesticides in 53 of the 96 counties in the study unit. The most commonly detected herbicide (63 samples) in surface water was atrazine. Five other pesticides--desethylatrazine, tebuthiuron, prometon, metolachlor, and simazine--were detected in 15 or more samples. The most commonly detected insecticide (13 samples) was p,p'-DDE. Two other insecticides, diazinon and cis-permethrin, were detected in seven or more samples. Pesticides were detected at 39 surface-water sites; samples collected at Yocum Creek near Oak Grove, Ark. had the most pesticide detections (13). Seventeen other sites had samples with six or more pesticide detections. Analysis of pesticide data collected at surface-water sites indicates that the largest variety of different pesticides detected (18) was in small, agricultural drainage basins; the largest percentage of detections of a single pesticide (about 80) was in medium, agricultural basins. Pesticide concentrations were small, and in most cases, at or near the detection limit. Maximum concentrations ranged from 0.001 to 0.007 micrograms per liter (mg/L) at small, forest sites; 0.001 to 0.029 mg/L at medium, forest sites; 0.001 to 0.079 mg/L at small, agricultural sites; and 0.003 to 0.29 mg/L at medium, agricultural sites. Pesticides were detected significantly more often in medium, agricultural basins in the Springfield Plateau. The most commonly detected (13 samples) organic compound in bed sediment, in concentrations noticeably above background levels, was 2,6-dimethylnaphthalene; the maximum concentration of 2,6-dimethylnaphthalene was 130 micrograms per kilogram. Seventeen or more compounds were detected in bed-sediment samples collected at three sites. Four compounds were detected in biological-tissue samples: p,p'-DDT in Corbicula fluminea (Asiatic clam) tissue collected at the Osage River near St. Thomas, Mo. and cis-chlordane, trans-chlordane, and trans-nonachlor in C. fluminea tissue collected at the James River near Boaz, Mo. Organic compounds collected at surface-water, bed-sediment, or biological-tissue sampling sites were not detected in concentrations that exceeded any health criteria or standards. Based on this information, organic compounds do not pose any widespread or persistent problems in the study unit.

Arkansas, Kansas, Missouri, Oklahoma↗

USGS1995

Water-quality assessment of the Ozark Plateaus study unit, Arkansas, Kansas, Missouri, and Oklahoma: Analysis of information on nutrients, suspended sediment, and suspended solids, 1970-92

Water-quality data collected during water years 1970-90 (October 1 to September 30) for 83 surface-water sites and during 1970-92 for 395 ground-water sites in the 48,000 square mile Ozark Plateaus study unit of the National Water Quality Assessment Program were analyzed using selected descriptive and statistical methods. The water- quality data include nutrient (nitrogen and phosphorus), suspended sediment, and suspended- solids data, and ancillary information such as fertilizer use, animal waste, sewage treatment plant, and land use. Statistically significant differences exist in surface-water quality that can be attributed to physiography, land use, and other effects. The sites that were considered to be substantially affected by sewage treatment plants had the largest concentrations of nutrients. Nutrient concentrations generally were larger at sites associated with agricultural basins than at sites associated with forested basins. Statistically significant differences existed in the quality of ground water that can be attributed to hydrogeologic and land-use effects. Nutrient concentrations generally were largest where the water source is indicated to be shallow in origin and where parts of the hydrogeologic units are in agricultural land-use areas. Water quality has changed at several surface-water sites since 1970. Nutrient concentrations appear to have increased at some sites and decreased at other sites. Causes of these apparent trends are not known, but many of the sites with apparent trends are in agricultural areas. Surface-water loads of nutrients and suspended sediment were affected by several factors including streamflow, climate, drainage area, reservoir operation, and inputs from point and nonpoint sources. Annual loads were largest in large basins, with large inputs of nutrients or sediment during periods of high streamflows at locations where reservoir operation effects are not substantial.

Arkansas, Kansas, Missouri, Oklahoma↗