Hydrochemical Assessment Methods for Analyzing the Effects of Acidic Deposition on Surface Waters
In analyzing the effects of acidic deposition on surface waters, a variety of assessment methods can be used. They include methods that illustrate the distribution of physical and chemical characteristics of surface waters across a geographic region and those that lend themselves to the analysis of individual basins. Within these two general areas, a variety of specific analyses can be performed.
The distribution of characteristics across a geographic region can be analyzed in many ways. One approach is to separate the information into the components making up the strong acid-base system and those comprising the weak acid-base system. The data can be presented in the form of histograms, spline diagrams, and frequency distributions.
The analysis of individual systems can provide a great deal of information regarding the processes influencing the acid-base characteristics of surface waters and groundwaters and the mechanisms by which those processes operate. Several different methods can be applied to extract this type of information, including the analysis of evapotranspiration and mass balance (ET/MB) within a system. This approach identifies various constituents that are produced or consumed within the basin, factoring in the concentrating effects of evapotranspiration. In conjunction with an ET/MB approach, an analysis of the dynamics of individual base cations and strong acid anions (C B /C A analysis) can help point out interactions among ions, which provides a means of process identification. Buffer system analysis can help to quantify the contributions of weak acids and bases to a system’s observed water quality. A rigorous assessment that combines all these analyses involves the application of dynamic models that take into account the interactions of the major processes supplying acid and base to the water flowing through a basin. All these assessment methods are discussed in detail and specific examples of their application are presented.
KeywordsBase Cation Groundwater Inflow Lake Evaporation Strong Acid Anion Blue Lake
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