HR: 1340h
AN: H23D-1456    [Abstracts]
TI: Hydrologic Flushing of Forest Soils and the Consequent Leaching of Nitrogen and Calcium During Rainstorms and Snowmelt, Catskill Mountains, New York
AU: * Murdoch, P S
EM: pmurdoch@usgs.gov
AF: US Geological Survey, 425 Jordan Rd, Troy, NY 112180 United States
AU: Burns, D A
EM: daburns@usgs.gov
AF: US Geological Survey, 425 Jordan Rd, Troy, NY 112180 United States
AU: McHale, M
EM: mmchale@usgs.gov
AF: US Geological Survey, 425 Jordan Rd, Troy, NY 112180 United States
AU: Lawrence, G B
EM: glawrenc@usgs.gov
AF: US Geological Survey, 425 Jordan Rd, Troy, NY 112180 United States
AB: Catskill Mountain streams in New York often receive pulses of NO3 during storms and snowmelt from watershed soils and acid deposition. This "flushing effect" of nutrients and acids was documented in forest-soil water through use of sequential lysimetry, in which soil-water was collected in equal-volume increments from zero-tension lysimeters placed within the soil profile. Stormflow in previously unsaturated soils began with percolation of water through the upper soil to the B horizon. NO3 pulses in soilwater during storms and snowmelt were typically delayed in the B-horizon relative to the O-horizon, indicating a percolation process for soil water movement between the lysimeters, but during the fall rains and spring snowmelt periods water-table measurements indicated that the B-horizon lysimeter was overtopped by the water table. Net flux was similar from throughfall and 0-lysimeters for individual events, suggesting that throughfall could either percolate unchanged through the soil column or that microbial release of N was rapid and similar to throughfall inputs. Patterns of change in O-Lysimeter concentrations during individual storms indicate repeated backflushing periods in which percolating acidic deposition or snowmelt from an individual event rose back into the O-horizon with a rising water table. This back-flushing phenomena may be enhancing the leaching of soil calcium beyond what would occur if acidic deposition was only percolating once through the O horizon . The sequential lysimetry method allowed investigators a more detailed look at N dynamics in forest soils than has been possible through the typical monthly lysimeter sampling strategy.
DE: 0414 Biogeochemical cycles, processes, and modeling (0412, 0793, 1615, 4805, 4912)
DE: 1865 Soils (0486)
DE: 1871 Surface water quality
DE: 1879 Watershed
SC: Hydrology [H]
MN: Fall Meeting 2005