land Article Optical Spectral Tools for Diagnosing Water Media Quality: A Case Study on the Angara/Yenisey River System in the Siberian Region Costas A. Varotsos 1,2 , Vladimir F. Krapivin 3, Ferdenant A. Mkrtchyan 3 and Yong Xue 2,4,* 1 Department of Environmental Physics and Meteorology, University of Athens, 15784 Athens, Greece;
[email protected] 2 School of Environment Science and Geoinformatics, China University of Mining and Technology, Xuzhou 221116, China 3 Kotelnikov Institute of Radioengineering and Electronics, Fryazino Branch, Russian Academy of Sciences, Fryazino, 141190 Moscow, Russia;
[email protected] (V.F.K.);
[email protected] (F.A.M.) 4 College of Science and Engineering, University of Derby, Derby DD22 3AW, UK * Correspondence:
[email protected] Abstract: This paper presents the results of spectral optical measurements of hydrochemical char- acteristics in the Angara/Yenisei river system (AYRS) extending from Lake Baikal to the estuary of the Yenisei River. For the first time, such large-scale observations were made as part of a joint American-Russian expedition in July and August of 1995, when concentrations of radionuclides, heavy metals, and oil hydrocarbons were assessed. The results of this study were obtained as part of the Russian hydrochemical expedition in July and August, 2019. For in situ measurements and sampling at 14 sampling sites, three optical spectral instruments and appropriate software were used, including big data processing algorithms and an AYRS simulation model. The results show Citation: Varotsos, C.A.; Krapivin, V.F.; Mkrtchyan, F.A.; Xue, Y. Optical that the water quality in AYRS has improved slightly due to the reasonably reduced anthropogenic Spectral Tools for Diagnosing Water industrial impact.