Geochemistry of the Springfield Plateau aquifer of the Ozark Plateaus Province in Arkansas, Kansas, Missouri and Oklahoma, USA

Abstract

Abstract:Geochemical data indicate that the Spring®eld Plateau aquifer, a carbonate aquifer of the Ozark Plateaus Province in central USA, has two distinct hydrochemical zones. Within each hydrochemical zone, water from springs is geochemically and isotopically dierent than water from wells. Geochemical data indicate that spring water generally interacts less with the surrounding rock and has a shorter residence time, probably as a result of owing along discrete fractures and solution openings, than water from wells. Water type throughout most of the aquifer was calcium bicarbonate, indicating that carbonate-rock dissolution is the primary geochemical process occurring in the aquifer. Concentrations of calcium, bicarbonate, dissolved oxygen and tritium indicate that most ground water in the aquifer recharged rapidly and is relatively young (less than 40 years). In general, ®eld-measured properties, concentrations of many chemical constituents, and calcite saturation indices were greater in samples from the northern part of the aquifer (hydrochemical zone A) than in samples from the southern part of the aquifer (hydrochemical zone B). Factors aecting dierences in the geochemical composition of ground water between the two zones are dicult to identify, but could be related to dierences in chert content and possibly primary porosity, solubility of the limestone, and amount and type of cementation between zone A than in zone B. In addition, speci®c conductance, pH, alkalinity, concentrations of many chemical constituents and calcite saturation indices were greater in samples from wells than in samples from springs in each hydrochemical zone. In contrast, concentrations of dissolved oxygen, nitrite plus nitrate, and chloride generally were greater in samples from springs than in samples from wells. Water from springs generally¯ows rapidly through large conduits with minimum water±rock interactions. Water from wells¯ow through small fractures, which restrict ow and increase water±rock interactions. As a result, springs tend to be more susceptible to surface contamination than wells. The results of this study have important implications for the geochemical and hydrogeological processes of similar carbonate aquifers in other geographical locations.

Using Multiple Chemical Indicators to Assess Sources of Nitrate and Age of Groundwater in a Karstic Spring Basin

“…The nitrate-N concentration in spring water greatly exceeds the 90th percentile value for well-water samples. Other studies in Assessing Sources of Nitrate and Age of Groundwater karst areas have found higher nitrate-N concentrations in spring waters relative to water from wells (Scanlon, 1990;Adamski, 2000).…”

“…Concentrations of the three CFC compounds and SF 6 ideally provide four independent ages, which can be used as a cross-check on sampling and analytical methods and to evaluate mixing processes. Analytical procedures for CFCs and SF 6 are described by Plummer (1992 and2000).…”

Using Multiple Chemical Indicators to Assess Sources of Nitrate and Age of Groundwater in a Karstic Spring Basin

“…The nitrate-N concentration in spring water greatly exceeds the 90th percentile value for well-water samples. Other studies in Assessing Sources of Nitrate and Age of Groundwater karst areas have found higher nitrate-N concentrations in spring waters relative to water from wells (Scanlon, 1990;Adamski, 2000).…”

“…Concentrations of the three CFC compounds and SF 6 ideally provide four independent ages, which can be used as a cross-check on sampling and analytical methods and to evaluate mixing processes. Analytical procedures for CFCs and SF 6 are described by Plummer (1992 and2000).…”

Lithology and disturbance drive cavefish and cave crayfish occurrence in the Ozark Highlands ecoregion

“…1 ). The Ozark Highlands ecoregion is relatively wet (97–122 cm of precipitation annually) with moderate temperatures (13–16 °C average annual temperature 42 ). Many lowland areas have been converted from native, warm-season grasses and oak, hickory, and pine forest to agriculture, whereas many upland areas remain forested 43 .…”

Summary of surface-water quality data from the Illinois River Basin in Northeast Oklahoma, 1970-2007

“…Surface water and groundwater in the Illinois River Basin and the surrounding Ozarks region generally contains large amounts of calcium and bicarbonate dissolved from limestone, making most water in the region relatively hard (Adamski, 2000). Nitrate dissolved in the water is derived from natural sources such as bedrock, and human activities such as agriculture, seepage of human wastewater from septic tanks, and discharges of municipal wastewater from point sources.…”

Using Multiple Chemical Indicators to Assess Sources of Nitrate and Age of Groundwater in a Karstic Spring Basin

“…The nitrate-N concentration in spring water greatly exceeds the 90th percentile value for well-water samples. Other studies in Assessing Sources of Nitrate and Age of Groundwater karst areas have found higher nitrate-N concentrations in spring waters relative to water from wells (Scanlon, 1990;Adamski, 2000).…”

“…Concentrations of the three CFC compounds and SF 6 ideally provide four independent ages, which can be used as a cross-check on sampling and analytical methods and to evaluate mixing processes. Analytical procedures for CFCs and SF 6 are described by Plummer (1992 and2000).…”

Lithology and disturbance drive cavefish and cave crayfish occurrence in the Ozark Highlands ecoregion

“…1 ). The Ozark Highlands ecoregion is relatively wet (97–122 cm of precipitation annually) with moderate temperatures (13–16 °C average annual temperature 42 ). Many lowland areas have been converted from native, warm-season grasses and oak, hickory, and pine forest to agriculture, whereas many upland areas remain forested 43 .…”

Summary of surface-water quality data from the Illinois River Basin in Northeast Oklahoma, 1970-2007

“…Surface water and groundwater in the Illinois River Basin and the surrounding Ozarks region generally contains large amounts of calcium and bicarbonate dissolved from limestone, making most water in the region relatively hard (Adamski, 2000). Nitrate dissolved in the water is derived from natural sources such as bedrock, and human activities such as agriculture, seepage of human wastewater from septic tanks, and discharges of municipal wastewater from point sources.…”

Using Multiple Chemical Indicators to Assess Sources of Nitrate and Age of Groundwater in a Karstic Spring Basin

“…The nitrate-N concentration in spring water greatly exceeds the 90th percentile value for well-water samples. Other studies in Assessing Sources of Nitrate and Age of Groundwater karst areas have found higher nitrate-N concentrations in spring waters relative to water from wells (Scanlon, 1990;Adamski, 2000).…”

“…Concentrations of the three CFC compounds and SF 6 ideally provide four independent ages, which can be used as a cross-check on sampling and analytical methods and to evaluate mixing processes. Analytical procedures for CFCs and SF 6 are described by Plummer (1992 and2000).…”

Lithology and disturbance drive cavefish and cave crayfish occurrence in the Ozark Highlands ecoregion

“…1 ). The Ozark Highlands ecoregion is relatively wet (97–122 cm of precipitation annually) with moderate temperatures (13–16 °C average annual temperature 42 ). Many lowland areas have been converted from native, warm-season grasses and oak, hickory, and pine forest to agriculture, whereas many upland areas remain forested 43 .…”

Summary of surface-water quality data from the Illinois River Basin in Northeast Oklahoma, 1970-2007

“…Surface water and groundwater in the Illinois River Basin and the surrounding Ozarks region generally contains large amounts of calcium and bicarbonate dissolved from limestone, making most water in the region relatively hard (Adamski, 2000). Nitrate dissolved in the water is derived from natural sources such as bedrock, and human activities such as agriculture, seepage of human wastewater from septic tanks, and discharges of municipal wastewater from point sources.…”