Download Spatial Pattern in Surface Water Chemistry in a Glaciated Catchment

Spatial Pattern in Surface Water Chemistry in a Glaciated
Catchment of the Adirondack Park, NY
S F Christopher (Department of Environmental and Forest Biology,
SUNY Environmental Science and Forestry, Syracuse, NY; ph. 315
470-6916; fax 315 470-6996; e-mail: [email protected]); S
Inamdar (Department of Geography and Great Lakes Center, SUNY
College at Buffalo, Buffalo, NY; ph. 716 878-4329; e-mail:
[email protected]); M J Mitchell (Department
of Environmental and Forest Biology, SUNY Environmental Science
and Forestry, Syracuse, NY; ph. 315 470 6765; fax 315 470-6996;
e-mail: [email protected])
Recently there has been considerable interest in investigating the
mechanisms responsible for the export of dissolved organic carbon
(DOC) and nitrate-N. We explored the mechanisms of solute export
and their variation with topography and season for a forested catchment
located in the Adirondack Park, NY. The 133ha Archer Creek
catchment was comprised of an assemblage of subcatchments
representing a range in topography, soils, drainage, and vegetative
features. Headwater subcatchments had steep hillslopes, bench-step
topography, surface springs, and older deciduous vegetation. In
contrast, subcatchments located lower in the watershed were poorly
drained with a disproportionately greater share of wetland and peatland
areas and coniferous vegetation (mostly black spruce).
We
hypothesized that the potential for export of solutes such as DOC and
nitrate from these contrasting subcatchment regimes would differ and
would be regulated by topography, drainage, and seasonal conditions.
We tested this hypothesis by conducting a continuous synoptic survey
of stream and groundwater chemistry for subcatchments located in the
headwaters and the lower portions of the catchment. Concentrations for
DOC and nitrate-N have been measured in stream grab samples at the
subcatchment outlets since July 1999. In addition, water table
elevations have been continuously monitored since October 2000. The
subcatchment located in the lower part of the catchment had highest
yearly mean DOC (816.67 umol/l) and lowest yearly mean nitrate-N
concentration (11.719 ueq/l). Groundwater elevations in this
subcatchment were close to the surface year-round indicating the
potential for near surface flushing of solutes. In contrast, subcatchments
located in the headwaters had lowest yearly mean DOC (137.24 umol/l),
highest yearly mean nitrate-N (56.05 ueq/l), and relatively deep
watertable elevations, suggesting the controls of deep flow paths on
solute export. Export of nitrate was influenced by season whereas
export of DOC showed little seasonal variation. Nitrate-N
concentrations reached their peak during spring for both the lower and
headwater subcatchments (51.98 ueq/l and 70.11 ueq/l respectively)
whereas the lowest values were recorded during the summer and fall
(undetectable ueq/l and 38.18 ueq/l respectively). This seasonal pattern
in nitrate concentration suggests a flushing response in the spring and
an alternate export mechanism during summer/fall. This study suggests
that export of solutes from this catchment occur via different processes
which vary with topography and season. Future research will explore
these seasonal differences of nitrate and DOC export in greater detail.