Petroleum Hydrocarbons In The Russian
PETROLEUM HYDROCARBONS IN THE RUSSIAN
COASTAL REGIONS OF THE BLACK SEA
S.G. Oradovski
State Oceanographic Institute Federal Service of Russia on the Hydrometeorology and Environmental Monitoring, Moscow, Russia
Russian part of the Black Sea includes waters near its northeastern coasts, from Primorsko-Ahtarsk to Sochi. Located here the towns of Novorossiysk and Tuapse are known to be the biggest oil transportation ports. Naturally, they produce a negative impact to environment. During the period of observations from 1980 to 1999, average concentrations of petroleum hydrocarbons (PHCs) in the Russian coastal waters varied from less than 0.05to 0.32 mg/l. The nationally adopted allowable concentration of oil and oil products as determined by arbitrate method of infrared spectrophotometry (Simard etc.1, also adopted by EPA, USA) equals 0.05 mg/l. Almost in all regions, the highest concentrations were found in 1980-1981, 1985- 1986. It is worth noting that a 5-6 year cycle of oil pollution concentration is clearly observed in the coastal waters. This is likely due to a strong meandering of the Main Black Sea Current and accumulation of petroleum hydrocarbons on its periphery (Oradovsky etc.2). In the rest of the years, the concentration of petroleum hydrocarbons decreased remarkably, with their values seldom exceeding the established levels.
Fig.1 shows the map of dynamic topography (in din.mm) on the sea surface according to survey data (Krivosheya etc.3):
a) 26.05 – 31.05 (to the left) and 08.06 –11.06.94 (to the right)
b) 25.08 –01.09.94 (all calculations made with reference to a surface of 300 db).
It has been established that eddies are formed within meander loops. Anticyclonic eddies are located to the right of the core stream of the Main Black Sea Current and move off the coast to northwest at an average velocity of 2-3 miles /day. An anticyclone eddy often lies southwest of Novorossiysk. In spring-summer, weakening of atmospheric circulation and predominately calm weather over the Black Sea basin cause a reduction in the velocity and
hydrodynamic stability of the current thus intensifying meander and eddy generation. This is clearly seen in the maps (Fig. 1,a b).
Under such water circulation conditions, the spatial patterns of average PHCs concentrations can be hardly predicted.
Before 1992 chemical monitoring of the Black Sea was carried out in the by the Russian, Ukrainian and Georgian organizations in the frames of the united program and using the united methods. This gave us the comparable data. At present the observations for the pollution of the Russian Part of the Black Sea are fulfilled episodically and using the incomplete program, because of the economical difficulties. Nevertheless, SOI, as before, carries out the scientific analysis of the obtained information, its generalization and publishing in the form of the special annual report, that is spreader among the interested organizations.
The reliability analysis of the revealing of the tendencies of changing the pollution level of the sea for different types of pollutants and for different time intervals was performed by SOI (Oradovski, Kirianov4). It was determined that the volume of observation, which is theoretically necessary for the true evaluation of difference between the concentrations of the pollutants on the level, equal to 0.5 of the limited concentration is equal to 15. This is true for the confidence level equal to 95%, with the error of the single analyses equal to 20% and the level of concentration of the pollutant from 2 to 3 of the limited concentration. Explain this fact on the concrete example. Average season concentration of petroleum hydrocarbons in the region of the seaport Anapa in 1988 was equal to 2 of the limited concentration and in 1990 it was equal to 2.5. This difference (0.5) is not important, because the average values were obtained using only 12 observations that are not satisfying the reliable criteria with the 95% confidence level. At the same time the difference equal to 0.5 of the limited concentration between average season contents of petroleum hydrocarbons in 1988 (2.5) and in 1990 (3.0), obtained using 16 observations, is important. Hence, in the first case we could not, and in the second case - we could say, that there is a tendency for the increasing of the level of the petroleum pollution of this region.
In some regions of the sea it is impossible to determine the tendency of pollution because the volume of observation is theoretically not enough. Although, there are regions where the real volume of observations is theoretically enough, nevertheless it does not allow determining the tendency of pollution even with the difference between average levels of concentration equal to 2-3 of the limited concentration. This tells us about high spatio-temporal variability of the fields of pollutants (for example, because of the
water dynamics), that doesn\’t allow to average the obtained observation data because of the high dispersion of the minimum and maximum values from the average arithmetical value. In such cases it is necessary to change the programs and the methodology of observation. It is not useful to spend money for improving the accuracy of the methods of the chemical analysis of samples without the changing of the methodology of the monitoring. As example we could examine the situation in the Sochi region in 1990 and 1991. In 1990 the average content of petroleum hydrocarbons in this region was equal to 2.5 of the limited concentration, and in 1991 - 2.0. In both cases for calculation there were taken data of 32 observations that was theoretically enough for smoothing out of the errors of the single determination. But the dispersion of the real concentrations relatively the average values were so large, that the difference (0.5) in this case is not important at the 95% confidence level. The reason of such large dispersion consists in high spatial variability fields of concentrations of petroleum hydrocarbons in the region of Sochi, where one could see both very polluted areas, and quite clean ones. Such situation is conditioned by complicated water dynamics, that is defined by the behaviour of the Main Black Sea Flow and by streams of the coastal zone. Streams of the coastal zone in the region Novorossiisk-Sochi, restricted by the selvage of the shelf, are quite changeable and have whirlwind character that depends on the local conditions. The Main Black Sea Flow is placed near the continental slope, 40-80 km wide, and has stream character. The boundaries between these zones are not fixed, especially during the development of the synoptic unsteady of the Main Black Sea Flow, nevertheless the hydrology exerts strong influence upon the character of the pollution of the Russian Part of the sea. For example, it is quite evident that because of cyclonic trend of the Main Black Sea Current some part of the pollutants enter the Russian aquatoria from the South, from Abhaz-Georgian aquatoria, thus make worse the condition of pollution of Russian waters, independently from the impact pollutant sources, placed in the regions of Anapa, Novorossiisk, Gelendjik, Tuapse, Sochi, Adler and others. Hence, for studying and evaluation of this condition it is necessary to observe not only the content of the pollutants in seawater, but also the velocity and direction of the streams.
Last few years the concentrations of PHCs were very low as it is clear visible in the Tabl.1. It is in a contradiction with the previous discussion. They are smooth and similar. It is possible that the reason is a drastic decreasing of PHCs discharge into the coastal waters from the land-based sources as well as decreasing of oil and oil’s products discharge from the Abkhazian and Georgian territories.
Table 1. The Indicators of the oil pollution of the Black Sea waters at the Russian coast in 1997-1999 (mg/l).
Region
Substance
Value
1997
1998
1999
Conc.
Limit. Conc.
Conc.
Limit. Conc.
Conc.
Limit.
Conc.
Anapa
PHCs
Mean
Max
0.05
0.09
1
0.08
Novorossiysk
PHCs
Mean
Max
0.06
> 1
0.06
> 1
Gelen-
Jik
PHCs
Mean
Max
0.06
0.20
4
0.05
0.05
1
1
Tuapse
PHCs
Mean
Max
0.08
0.06
> 1
0.05
1
Sochi
PHCs
Mean
Max
References
1. Simard R., Hasegava I. a.o. IRS Determination of oil and phenols in water.- Anal.Chem. 1951, v.23, № 10, p.1384-1387.
2. Oradovsky S.G., Afanasyeva N.A. a.o. Assessment of the Chemical Pollution Level in the Russian basins in Caspian, Black and Azov Seas during 1980-1995. Oceanology,1997,v.37, № 6, p.862-867.
3. Krivosheya V.G., Ovchinnikov I.M. a.o. Meandering of the Main Black Sea current and eddies formation in the North-Eastern part of the Black Sea in summer 1994. Oceanology, 1998, vol.38, № 4, p.546-553.
4. Oradovsky S.G., Kirianov S.V. Development of the Chemical Monitoring System on the Russian Part of the Black Sea. Abstr.of the Meeting of the Euro-Mediterranean Marine Centres, Malta, 1994, p.1.
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