Applications
The SWAS-VTSSS program has been maintained, in large part, to evaluate the response of streams in the Appalachian region to ongoing decreases in acid deposition (Fig. 1) stemming from the implementation of the 1990 Clean Air Act Amendments (Riscassi, Scanlon, & Galloway, 2019; Robison, Scanlon, Cosby, Webb, & Galloway, 2013; Scanlon, Riscassi, & Galloway, in review; Webb et al., 2004). Notably, a National Atmospheric Deposition Program (NADP) site, which measures analytes in precipitation, was established in 1981 in central SHEN (Fig. 2), providing the data necessary to reliably quantify and assess changes to watershed retention/export of individual ions through mass balance calculations (Robison et al., 2013) and to gain insight into the watershed characteristics responsible for regional differences in recovery (Eng & Scanlon, in review). The physical and chemical data may also be used to 1) identify driving factors of biological trends (e.g. Blum, Kanno & Letccher, 2018), 2) determine the most appropriate locations to investigate atmospheric pollutants, such as mercury, in both aqueous (e.g. Riscassi & Scanlon, 2011) and biological (e.g. Eagles-Smith et al., 2020) environments, 3) calibrate and validate biogeochemical models for prediction of climate change impacts (e.g. Robison & Scanlon, 2018), and 4) assesses the hydrologic and chemical response to watershed disturbances such as insect defoliations (e.g. Eshleman, Morgan, Webb, Deviney, & Galloway, 1998), catastrophic flood events (e.g. Reinhardt & Furman, 2008), and fire (e.g. Jensen, Scanlon, & Riscassi, 2017) (Fig. 1).