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Hot On The Heels Of Oil Pollution

October 12, 2001

Who spilled the oil? This is not an idle inquiry especially when the damage is enormous. To catch the culprits red-handed and prove their guilt is very difficult. That is why the identification of the sources which are responsible for oil pollution seems to be one of the major environmental problems all over the world. However, thanks to efforts of Russian scientists at St. Petersburg State Technological Institute and All-Russian Scientific Research Institute of Metrology named after D.I. Mendeleev this problem has been solved, at least in Khanty-Mansiysk Autonomous Region.
      
The larger half of all oil in Russia is extracted exactly in this region that is about 160-170 million tons. The land is crammed with oilfields here and numerous wells are located close to each other. Of course, accidents happen at oil pipelines inevitably, oil is spread with water, and to find the source of pollution is very difficult. If the oil from each oilfield had its own individual characteristic it would be possible to compare the probes of oil pollution with the characteristics of oilfields and find out the source. It is the task that the scientists tried to solve for Khanty-Mansiysk Autonomous Region for the first time.
      
They investigated the oil probes of six oilfields (Alekhinskoe, Lyantorskoe, Prirazlomnoe, Priobskoe, Krasnoleninskoe, Trekhozernoe) taken from the wells on the territory of the region and also the probes of soil and water which were polluted with the oil products. To reveal reliable differences in the compositions of the probes the scientists brought all modern analytical methods into action: capillary gas-liquid chromatography, chromato-mass-spectrometry, Fourier IR spectrometry, gamma spectrometry. It is worth mentioning that the first two methods are used most often when solving similar analytical tasks.
      
What did the results show? It turned out that the first two methods did not distinguish between oil probes. It is quite natural because the oilfields are located nearby and the composition of the oil differs little. However, the task was to distinguish between the probes reliably and here gamma spectrometry, which detects radioactive isotopes in the probes, helped the scientists a lot.
      
There is no mystery about the fact that all oilfields lie in different rocks and differ in the composition of natural radionuclides. It turns out that the composition of radionuclides in different rocks is transmitted to the oil. This characteristic is individual and can serve as the radiation print of oil. The results of the experiments which were carried out using gamma spectroscopy confirmed the suggestion the scientists had made: all six probes, i.e. all six oilfields, differed dramatically in the composition of radionuclides (thallium-208, bismuth-212, lead-212, actinium-228, bismuth-214, lead-214, pottassium-40). And in spite of the fact that the total content of radioactive isotopes in the oil of Khanty-Mansiysk Autonomous Region is not great, gamma-spectrometry enables distinguishing between oil probes from different oilfields and in such a way finding the sources of pollution.
      
The authors reckon that the method will be especially useful when two or more oil sources are responsible for the pollution of the environment.


Informnauka (Informscience) Agency