A Biogeochemical Comparison of Two Well-Buffered Catchments with Contrasting Histories of Acid Deposition

Abstract

Abstract. Much of the biogeochemical cycling research in catchments in the past 25 years has been driven by acid deposition research funding. This research has focused on vulnerable base-poor systems; catchments on alkaline lithologies have received little attention. In regions of high acid loadings, however, even well-buffered catchments are susceptible to forest decline and episodes of low alkalinity in streamwater. As part of a collaboration between the Czech and U.S. Geological Surveys, we compared biogeochemical patterns in two well-studied, well-buffered catchments: Pluhuv Bor in the western Czech Republic, which has received high loading of atmospheric acidity, and Sleepers River Research Watershed in Vermont, U.S.A., where acid loading has been considerably less. Despite differences in lithology, wetness, forest type, and glacial history, the catchments displayed similar patterns of solute concentrations and flow. At both catchments, base cation and alkalinity diluted with increasing flow, whereas nitrate and dissolved organic carbon increased with increasing flow. Sulfate diluted with increasing flow at Sleepers River, while at Pluhuv Bor the sulfate-flow relation shifted from positive to negative as atmospheric sulfur (S) loadings decreased and soil S pools were depleted during the 1990s. At high flow, alkalinity decreased to near 100 µeq L −1 at Pluhuv Bor compared to 400 µeq L −1 at Sleepers River. Despite the large amounts of S flushed from Pluhuv Bor soils, these alkalinity declines were caused solely by dilution, which was greater at Pluhuv Bor relative to Sleepers River due to greater contributions from shallow flow paths at high flow. Although the historical high S loading at Pluhuv Bor has caused soil acidification and possible forest damage, it has had little effect on the acid/base status of streamwater in this well-buffered catchment.

Approaches to stream solute load estimation for solutes with varying dynamics from five diverse small watersheds

“…Four dissolved chemical solutes were included in this analysis: sulfate (SO 2− 4 ), silica (Si), nitrate (NO − 3 ), and dissolved organic carbon (DOC). These solutes were selected because they differ in their sources, predominant hydrologic flowpaths, and biogeochemical reactivities at these watersheds (Johnson et al 1969, Lawrence and Driscoll 1990, Stoddard and Murdoch 1991, Shanley and Peters 1993, Huntington et al 1994, Burns et al 1998, Shanley et al 2004, Peters et al 2006, Sebestyen et al 2009, 2014 resulting in a wide range of solute dynamics that are expected to be representative of many solutes at other sites. The most important differentiating characteristics of these solutes are that SO 2− 4 is atmospherically derived and can be somewhat reactive, Si is a weathering product that behaves conservatively, and NO − 3 and DOC are biogeochemically controlled and have contrasting strengths of concentration-discharge relations.…”

“…Samples at Panola were not analyzed for DOC for a sufficiently long period to include in this analysis. Storms were sampled at Río Mameyes sporadically through- Bailey 1976, McNab and Avers 1994, Griffith et al 2001, and Bryce et al 2010. ¶ Shanley et al (2004.…”

Mercury dynamics in relation to dissolved organic carbon concentration and quality during high flow events in three northeastern U.S. streams

“…Watershed 9 has an area of 41 ha and ranges in elevation from 519 to 686 m. Streamflow is measured with a broad-crested V-notch weir. Watershed 9 is a forested, calcareous catchment with areas of poor drainage supporting small wetlands, peat, and mucky riparian soils [Shanley et al, 2004]. The catchment is underlain by the Waits River Formation, a sulfidic calcareous granulite interbedded with micaceous phyllites and biotite schists that generates neutral pH, calcium-bicarbonate-sulfate waters [Hall, 1959;Bailey et al, 2004;Mitchell et al, 2008].…”

Change in winter climate will affect dissolved organic carbon and water fluxes in mid‐to‐high latitude catchments

“…There is no permafrost, but soil frost depth can reach to 60 cm during winter (Mellander et al, 2007). The forested W-9 catchment at Sleepers River, Vermont, USA, has a humid continental climate (Shanley et al, 2004), with T, P and Q of 4.7 C, 1256 mm and 743 mm, respectively. Soil frost is intermittent and is usually <10 cm in the forest (Shanley and Chalmers, 1999).…”