Adapted methodology for comprehensive contamination assessment of bottom sediments on the content of various forms of heavy metals

As a result of long-term studies of bottom sediments of lakes, rivers, ponds and reservoirs of the Republic of Tatarstan, considerable factual material has been accumulated, which enabled the translation of quantitative estimates into qualitative characteristics. This necessitated a comprehensive assessment and generalization of the exceedance of the thresholds set for all metals, similarly to the specific combinatorial water pollution index (SCWPI). At the same time, the authors emphasize the features of such a comprehensive assessment of bottom sediments, and also suggest methods and algorithms for solving emerging problems. We use the method of frequency characteristics of data series of metal content (Cd, Pb, Co, Cu, Ni, Zn, Cr, Mn, Fe) in bottom sediments, score the relevant characteristics, generalize the point estimates and bring them to the appropriate classes of purity. As a result, a method for the integrated assessment of contamination of bottom sediments was developed and tested, which solves the problem of the integral assessment of the quality of bottom sediments in terms of a complex of pollutants using the example of heavy metals. The method is based on the approach of the SCWPI. Therefore, its results are comparable to combinatorial assessments of water quality, which will allow deriving a uniform assessment of the water body as a whole.