Institute of Oceanology, Bulgarian Academy of Sciences, P.O. Box 152, Varna, Bulgaria; SuRDEP, 15 La Vue, Wierda Glen Estate, Pretoria, South Africa
Shtereva, G., Institute of Oceanology, Bulgarian Academy of Sciences, P.O. Box 152, Varna, Bulgaria; Velikova, V., SuRDEP, 15 La Vue, Wierda Glen Estate, Pretoria, South Africa; Doncheva, V., Institute of Oceanology, Bulgarian Academy of Sciences, P.O. Box 152, Varna, Bulgaria
Main drivers implying impact on the Black Sea water quality (WQ) along the Bulgarian coast are industry, urbanisation, tourism, navigation and agriculture. The aim of this paper is identification and evaluation of land-based sources (LBS) contributing to the nutrient enrichment of Black Sea coastal areas. Polluted rivers and municipal wastewater treatment plants (WWTPs) discharges are accountable for excessive enrichment of sea waters with nitrogen, phosphorus and organic matter. The majority of municipal WWTPs, located along the Bulgarian coast, directly discharge into the sea and provide 68% of the total nitrogen load and 15% of the total phosphorus load. Additionally, wastewaters from 5 sewages flow into the sea without any treatment. A few WWTPs discharge into coastal lakes connected to the sea. Their impact on the Black Sea is indirect, yet significant due to the large pollutants load they bring to the environment. A number of new touristic facilities in Bulgarian resorts are not connected to the sewage system. Besides, some WWTPs have insufficient capacity to treat the increased amount of wastewaters delivered in summer, often they discharge insufficiently treated waters to the Black Sea which results in elevated nutrients level in coastal waters. The largest river along the Bulgarian coast is Kamchia, and it is also the most significant source of nutrients and pollutants for the Bulgarian Black Sea waters. Analysis of available data on nutrients load reveals three areas of maximum anthropogenic impact along the Bulgarian coast. These are the Varna and Burgas bays, and the Kamchia river mouth, which are exposed to direct or indirect influence of industrial and municipal discharges, port operations, tourism development and also inputs of nutrients from diffuse sources.
