The application of an integrated biogeochemical model (PnET‐BGC) to five forested watersheds in the Adirondack and Catskill regions of New York

Abstract

Abstract:PnET-BGC is an integrated biogeochemical model formulated to simulate the response of soil and surface waters in northern forest ecosystems to changes in atmospheric deposition and land disturbances. In this study, the model was applied to five intensive study sites in the Adirondack and Catskill regions of New York. Four were in the Adirondacks: Constable Pond, an acid-sensitive watershed; Arbutus Pond, a relatively insensitive watershed; West Pond, an acidsensitive watershed with extensive wetland coverage; and Willy's Pond, an acid-sensitive watershed with a mature forest. The fifth was Catskills: Biscuit Brook, an acid-sensitive watershed. Results indicated model-simulated surface water chemistry generally agreed with the measured data at all five sites. Model-simulated internal fluxes of major elements at the Arbutus watershed compared well with previously published measured values. In addition, based on the simulated fluxes, element and acid neutralizing capacity (ANC) budgets were developed for each site. Sulphur budgets at each site indicated little retention of inputs of sulphur. The sites also showed considerable variability in retention of NO 3 . Land-disturbance history and in-lake processes were found to be important in regulating the output of NO 3 via surface waters. Deposition inputs of base cations were generally similar at these sites. Various rates of base cation outputs reflected differences in rates of base cation supply at these sites. Atmospheric deposition was found to be the largest source of acidity, and cation exchange, mineral weathering and in-lake processes served as sources of ANC.

Long-Term Effects of Acidic Deposition on Water Quality in a High-Elevation Great Smoky Mountains National Park Watershed: Use of an Ion Input–Output Budget

“…Current export of base cations may be moderating acidification of high-elevation streams in the GRSM; however, if this cation pool becomes exhausted and acidic deposition persists, acidification of streams could accelerate in the future. This long-term study provides essential information for use in a biogeochemical model in order to predict future conditions and depositional critical loads (Chen et al 2004;Sullivan et al 2004Sullivan et al , 2007Sullivan et al , 2008. Porter et al (2005) cites the need for regional critical loads to protect aquatic resource protection of federal lands, including the GRSM.…”

Comparisons of watershed sulfur budgets in southeast Canada and northeast US: new approaches and implications

“…Sulfate losses in drainage waters exceed estimated atmospheric inputs for most studies that have calculated watershed S budgets in southeastern Canada (Houle and Carignan 1995;Houle et al 1997;Beall et al 2001;Eimers and Dillon 2002;Eimers and Houle 2005;Duchesne and Houle 2006) and the northeastern US (Likens and Bormann 1995;Driscoll et al 1998;Likens et al 2002;Park et al 2003). The application of biogeochemical models for estimating watershed S dynamics have also suggested discrepancies as estimated by the difference between estimated atmospheric S inputs and drainage losses as SO 4 2- (Chen et al 2004;Gbondo-Tugbawa et al 2002). The role of discrepancies in ecosystem S budgets needs to be understood when making policy decisions relating the expected effect of changing emissions and resultant atmospheric deposition to ecosystem response including the response of surface waters (e.g., Driscoll et al 2001;Sullivan and Cosby 2005).…”

Importance of within-lake processes in affecting the dynamics of dissolved organic carbon and dissolved organic and inorganic nitrogen in an Adirondack forested lake/watershed

“…The effects of changes of acidic deposition on surface water, including trends in DOC concentrations, have been documented in North America and Europe (Erlandsson et al, 2011;Evans et al, 2007;Kalbitz et al, 2000;Monteith et al, 2007Monteith et al, , 2015Mulder et al, 2001). However, for Arbutus Lake the effects of changes in acidic deposition may be less evident due to its relatively high pH (∼ 6.7) and ANC (∼ 77 µeq L −1 ) values and base status (Foster et al, 1992;Johnson and Lindberg, 1992;Mitchell et al, 2001;Chen et al, 2004;NYSERDA, 2011).…”