AGW01 Long-term measurement of groundwater physical and chemical properties from wells on watershed N04D

In 1988 and 1990, the U.S.Geological Survey, Lawrence, KS, drilled 31 wells at 20 sites within the N04D watershed at the Konza Prairie Research Natural Area. The wells range in depth from about 2 to 13 meters, and are nested to include wells completed in alluvium/colluvium near the N04D drainage and in two Permian-aged limestone’s. In 1997, Konza LTER drilled an additional 4 wells at 3 sites, that range in depth from about 12 m to 37 m. The sites comprise four transects running approximately east-west across the drainage, and occupy the lower one-quarter of the surface area of the watershed. The geology of the area is characterized by patchy, near-stream alluvium/colluvium which overlies bedrock that is composed of thin (1-2 meter) limestones alternating with thicker (2-4 meter) shales. Beginning in 1990, water levels were measured and water samples collected quarterly. Since 1991, water levels have been measured and water samples for inorganic chemical analysis have been collected every four to six weeks; sample collection is by bailing wells after removing 1-2 well volumes of groundwater. The groundwater is then filtered through 0.45 micro; membrane filters by gravity feed or using a peristaltic pump. One 250-mL LDPE bottle is filled with 250 mL of sample and 5 mL of concentrated HNO<sub>3</sub> for determination of major and minor cation concentrations. One 250-mL LDPE bottle is filled to the brim for anion determination by ion chromatography and alkalinity determination by titration with 0.02 N H2SO4</sub>. The bottles are stored on ice and later in a refrigerator.