Contamination of the south-eastern Baltic Sea and the curonian lagoon with oil products

The development of complex investigations is a useful tool for determining of the marine environment contamination with oil products. In the frame of national monitoring program, the concentrations of total oil hydrocarbons (THCs) and polycyclic aromatic hydrocarbons (PAHs) in water and bottom sediments were analyzed and numbers of oil-oxidizing bacteria were determined. Investigations show that THC concentrations in water frequently exceed the maximum permissible level (0.05 mg/L). Long-term studies show that there is an increasing tendency of THC concentrations in some regions of the Lithuanian part of the Baltic Sea. Concentrations of PAHs in water of the Baltic Sea and the Curonian Lagoon do not exceed maximum permissible levels. PAH concentrations in sediments are close to background values. Investigation result also reveal that the contamination of sediments with PAHs is apparently coming from the use of diesel engines. The comparison of quantitative annual distribution of oil-oxidizing bacteria in different regions shows that they occur in greater abundance in the intermediate waters, i.e. in the Baltic Sea area which is under the impact of the Curonian Lagoon waters and in the Klaipeda Strait. According to the investigation results of THCs, PAHs and oil-oxidizing bacteria, the Klaipeda Strait is the mostly contaminated with oil products. Complex investigations and monitoring of marine environment allow permanent control of the contamination and quality of the Baltic Sea and the Curonian Lagoon environment.