caa a22 4500 445814691 CHVBK 20180317145222.0 cr unu---uuuuu 170323e20110901xx s 000 0 eng 10.1007/s10040-011-0750-1 doi (NATIONALLICENCE)springer-10.1007/s10040-011-0750-1 Relations of hydrogeologic factors, groundwater reduction-oxidation conditions, and temporal and spatial distributions of nitrate, Central-Eastside San Joaquin Valley, California, USA [Elektronische Daten] [Matthew Landon, Christopher Green, Kenneth Belitz, Michael Singleton, Bradley Esser] Relation entre facteurs hydrogéologiques, conditions d'oxydo-réduction de nappe et distribution temporelle et spatiale des nitrates, Centre-Est, de la San Joaquin Valley, Californie, USA In a 2,700-km2 area in the eastern San Joaquin Valley, California (USA), data from multiple sources were used to determine interrelations among hydrogeologic factors, reduction-oxidation (redox) conditions, and temporal and spatial distributions of nitrate (NO3), a widely detected groundwater contaminant. Groundwater is predominantly modern, or mixtures of modern water, with detectable NO3 and oxic redox conditions, but some zones have anoxic or mixed redox conditions. Anoxic conditions were associated with long residence times that occurred near the valley trough and in areas of historical groundwater discharge with shallow depth to water. Anoxic conditions also were associated with interactions of shallow, modern groundwater with soils. NO3 concentrations were significantly lower in anoxic than oxic or mixed redox groundwater, primarily because residence times of anoxic waters exceed the duration of increased pumping and fertilizer use associated with modern agriculture. Effects of redox reactions on NO3 concentrations were relatively minor. Dissolved N2 gas data indicated that denitrification has eliminated >5mg/L NO3-N in about 10% of 39 wells. Increasing NO3 concentrations over time were slightly less prevalent in anoxic than oxic or mixed redox groundwater. Spatial and temporal trends of NO3 are primarily controlled by water and NO3 fluxes of modern land use. Springer-Verlag (outside the USA), 2011 Groundwater monitoring nationallicence Hydrochemistry nationallicence Groundwater protection nationallicence Nitrate nationallicence USA nationallicence Landon Matthew US Geological Survey, 4165 Spruance Road, Suite 200, 92101, San Diego, CA, USA aut Green Christopher US Geological Survey, 345 Middlefield Rd., 94025, Menlo Park, CA, USA aut Belitz Kenneth US Geological Survey, 4165 Spruance Road, Suite 200, 92101, San Diego, CA, USA aut Singleton Michael Environmental Radiochemistry Group, Lawrence Livermore National Laboratory, 7000 East Ave., L-231, 94550, Livermore, CA, USA aut Esser Bradley Environmental Radiochemistry Group, Lawrence Livermore National Laboratory, 7000 East Ave., L-231, 94550, Livermore, CA, USA aut Hydrogeology Journal Springer-Verlag 19/6(2011-09-01), 1203-1224 1431-2174 19:6<1203 2011 19 10040 https://doi.org/10.1007/s10040-011-0750-1 text/html Onlinezugriff via DOI 1 research-article jats NATIONALLICENCE 856 40 https://doi.org/10.1007/s10040-011-0750-1 text/html Onlinezugriff via DOI NATIONALLICENCE 700 1- Landon Matthew US Geological Survey, 4165 Spruance Road, Suite 200, 92101, San Diego, CA, USA aut NATIONALLICENCE 700 1- Green Christopher US Geological Survey, 345 Middlefield Rd., 94025, Menlo Park, CA, USA aut NATIONALLICENCE 700 1- Belitz Kenneth US Geological Survey, 4165 Spruance Road, Suite 200, 92101, San Diego, CA, USA aut NATIONALLICENCE 700 1- Singleton Michael Environmental Radiochemistry Group, Lawrence Livermore National Laboratory, 7000 East Ave., L-231, 94550, Livermore, CA, USA aut NATIONALLICENCE 700 1- Esser Bradley Environmental Radiochemistry Group, Lawrence Livermore National Laboratory, 7000 East Ave., L-231, 94550, Livermore, CA, USA aut NATIONALLICENCE 773 0- Hydrogeology Journal Springer-Verlag 19/6(2011-09-01), 1203-1224 1431-2174 19:6<1203 2011 19 10040 Metadata rights reserved Springer special CC-BY-NC licence nationallicence BK010053 XK010053 XK010000 NATIONALLICENCE NATIONALLICENCE NL-springer