The chemistry of streams in southwestern and central Nova Scotia, with particular reference to catchment vegetation and the influence of dissolved organic carbon primarily from wetlands

The percentage of wetlands in a catchment accounted for about half of the variance in transformed data for concentrations of dissolved organic carbon (DOC) in 42 Nova Scotian streams draining catchments with 11 different kinds of vegetation. Color increased with DOC, as did total dissolved nitrogen (TDN). Thecolor/DOC andDOC/TDN quotients also rose with increasing DOC, indicating a change in the quality of dissolved organic matter with increasing wetland influence. Dissolved Fe, and to a much lesser extent dissolved Al, showed a strong positive correlation with DOC. Stream pH showed a strong negative correlation with DOC, largely from wetlands, and a strong positive correlation with non- marine Ca2+ weathered from mineral soils. Non-marine SO42− from acid deposition had no apparent influence on stream pH and decreased with increasing streamwater DOC in summer, presumably owing to reduction processes in wetlands that mitigated the effects of acid deposition. Apparently, these reduction processes also produced small amounts of dissolved, non-ionic organic sulfur. Non-marine Ca2+ was related strongly to the percentage of upland hardwood forests in the catchments. Wetlands exert a profound influence on the chemistry of streams, principally through their export of DOC but also because of reduction reactions in their anerobic peats.