SOME METHODOLOGICAL ASPECTS OF OIL POLLUTION EVALUATION OF WATER BODIES BASED ON THE DEGRADATION OF PETROLEUM PRODUCTS OVER TIME
This article is focused on the analytical aspects to be addressed when evaluating an oil pollution of aqueous ecosystems associated with a complexity of oil and petroleum product content and its transformation after entering the water environment. The field of application of different determination techniques of petroleum products in water and sediments is considered based on the example of the analysis of petroleum product determination methods included in the State Registry of methods approved for the state ecological control and monitoring, and on the experimental data of Azov Sea water and sediments monitoring. Over time, the ratio of the optical properties of petroleum hydrocarbons in IR-spectral region is changing because of their qualitative and quantitative transformation, which leads to significant inconsistencies in data obtained by different methods. It is shown that hydrocarbons accumulated in samples of water and sediments are different in their content: the polycyclic aromatic hydrocarbons accumulated in sediments resist the degradation while their proportion in aqueous medium is insignificant. For an adequate evaluation of oil pollution of aqueous ecosystem the advisability to measure several optical characteristics (the absorption intensity in IR-spectral region and luminescence intensity) is shown. The opportunity to use a certain mixture as a standard solution of hydrocarbons for graduation curves in the analysis of water bodies for IR-spectral and luminescence determination methods of petroleum products is described. The proposed mixture consists of 37% hexadecane, 33% isooctane, 29.97% benzene и 0.03% fluoranthene (weight %). It has the total extinction coefficient equal to the extinction coefficient of Simard mixture, and the intensity of its luminescence occupies an intermediate position between the most disparate lightweight and heavy-weight petroleum products as well as coincides with the intensity of the bilge water which is the main source of oil pollution in water bodies.