Agro-ecological assessment of Sokolitsa river water affected by open coal mining activity in the largest energy complex in Bulgaria

DIYANA DERMENDZHIEVA1, GERGANA KOSTADINOVA1, GEORGI PETKOV1, RODNE NASTOVA2 and IVETA DINEVA1
1 Trakia University, Faculty of Agriculture, Department of Applied Ecology and Animal Hygiene, BG – 6000 sStara Zagora, Bulgaria
2 University ‘Ss. Cyril and Methodius’, Institute of Animal Science, MK – 1000 Skopje, Republic of Macedonia

Abstract

DERMENDZHIEVA, D., G. KOSTADINOVA, G. PETKOV, R. NASTOVA and I. DINEVA, 2018. Agroecological assessment of Sokolitsa river water affected by open coal mining activity in the largest energy complex in Bulgaria. Bulg. J. Agric. Sci., 24 (Suppl. 1): 169–179

A study of Sokolitsa River was conducted with two monitoring points (MPs) – MP-1, before, and MP-2, after discharge of mining wastewater. The study was carried out during the summer months of the period 2013-2016 by assesing five physicochemical indices, eight heavy metals and metalloids, and three biotic parameters, and the water quality as a natural source and as a source for irrigation. For the sampling of water, living organisms and sample preparation, international ISO and BSS references were used. Sample analyses were made by Multi 340i, spectrophotometric methods and AAS. Based on the obtained analytical results, the following main conclusions were drawn: a) ecological assessment of the river water as a natural source determines water in both monitoring points as water in ‘good ecological status’ by pH values and in ‘moderate ecological status’ by Dissolved oxygen, Electroconductivity, Ecological Quality Rang, IPS and Biotic index values; b) the priority pollutants levels - Cd, Pb and Ni do not exceed the environmental quality standards and determine the water in ‘good chemical status’; c) the average element concentrations for the study period decreased in the following order Fe>Mn>Zn>Cu>Pb>Ni>Cr>Cd, which are not risky for the hydroecosystem and for irrigated crops; d) assessment of the river water as a source for irrigation determines the water in both monitoring points as appropriate for this purpose by all investigated parameters; e) the wastewater from open coal mining activities, discharged into the river has no significant impact on water quality as a natural source and as a source for irrigation.

Keywords:river water, physicochemical and hydrobiological parameters, heavy metals, mining wastewater, water quality
List of abbreviations:BI - Biotic index, DO - Dissolved oxygen, EC - Electroconductivity, EQR – Ecological Quality Rang, GES - Good ecological status, IPS - Diatomic index, MPC - Maximum permissible concentration, MES - Moderate ecological status, MP - Monitoring point, SS - Suspended solids

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