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1.4.5. Water Pollution A. Point Sources Nutrients According to the data collected throughout the Southern Caspian coastline from 19 stations, the following results have been obtained concerning the concentration of nutrients in the seawater (Table ?): Phosphates (PO4) The range of PO4 seawater content is between 0.03 and 0.15 ppm with an average of 0.06 ppm. The maximum standard level (WHO, 1984) of phosphate in surface seawater is 1 ppm, therefore none of the 19 stations were polluted according to this standard. The seawater PO4 content at each station is presented in fig.11. According to the results obtained, the average concentration of PO4 on the eastern side of the sea (0.08 ppm) is more than that of the western side (0.05 ppm). The maximum amount was observed in Chapak-rood River and in Ghare-soo River and Chaloos area, and the minimum in Jaf-rood River. Nitrates (NO3) The range of nitrate concentration in the surface seawater is between 0.03 and 0.41 ppm with an average of 0.21 ppm, therefore none of the stations surveyed had a level more than standard. Again, the average amount on the eastern side of the sea (0.21 ppm) is more than the western side (0.20 ppm). The surface seawater in Sefid-rood, Chaloos, Lang-rood and Tonekabon regions possess the highest concentrations and Chapak-rood, Anzali and Kapoorchal proved to have the lowest amount of nitrate contents (Table ?). Estimation of input To determine the river nutrients loads into the sea, sampling was carried out on samples from 7 stations situated on the river mouth, taking into account the total annual volume discharged by each river and following results were obtained (Table? and Table ?): As a whole, the maximum river nutrient load was observed at the Sefid-rood estuary (1840 tons per year) followed by Chaloos river estuary (171 tons per year), the lowest loads were observed at extreme west (Astara) and east (Ghare-soo) coastal estuaries. The annual total load of these rivers is estimated to be 2288 tons. Total Suspended Solids (T.S.S) and BOD Above mentioned surveys indicate that the amount of T.S.S in seawater is more than the standard limit (WHO, 1984) in all stations of the urban and agricultural sewage are the main source of such a high T.S.S. level. Astara station demonstrates the highest contamination followed by Ghare-soo and Palangan stations. The minimum amount is observed in Babol-rood region having a level below the standard limits (Table ? and Table ?). The amount of BOD was measured only in three stations, results indicate levels below the standard level (WHO, 1984) ranging from 2.33 -13.27 ppm (Table ? and Table ?). Amongst the five rivers investigated, Gorgan River with 40.5% total suspended material has the maximum load, and Babol-rood River with 9.8% has the minimum load. The total TSS load of these (5 rivers) into the sea is estimated to be about 163 thousand tons annually (Table ? and Table ?). Petroleum Hydrocarbons In Water Based on the results obtained from investigations made at 9 sampling stations along the Caspian Sea coastal zone, from Astara to Babolsar, (Table ? and Table ?), the average concentration of petroleum hydrocarbons is negligible, reaching 2.2 ppb, therefore water of these areas could be considered unpolluted. In Sediments Data obtained (Table ?) reveals that petroleum concentrations in the sediment of sampling stations ranges from slightly polluted (18.6 ppm) up to heavily polluted (85.12 ppm). The average Petroleum content at all these stations is 42.7 ppm, therefore the whole region could be regarded as moderately polluted. The distribution pattern of petroleum contamination along the entire coast reveals that, the maximum concentration of petroleum hydrocarbons occur in the middle region (from Sefid-rood to Babol-rood), and the eastern coastal region is the least polluted (Fig.15). Different sources of these pollutions are discussed in section 1-2-5. Estimation of Input The petroleum hydrocarbon input by rivers, flowing into the Caspian Sea has been measured for two rivers, Astara (west) and Shafa-rood (South of Astara). Approximately 0.61 tons of petroleum hydrocarbons annually enter the Caspian Sea through these two rivers (Table ? and Fig.15). Further studies are needed to measure input of all other rivers in order to calculate the total petroleum hydrocarbons discharge into the sea. Heavy Metals Heavy metals concentrations in the marine organisms, sediments and water of the Caspian Sea have been measured (Table 15, Fig.16) and results obtained are discussed in this section. Biota Fishes: Various degrees of heavy metals concentration have been determined in different fish muscles. Based on the degrees of heavy metal concentration the pollution could be classified as: un-polluted, slightly polluted, and heavily polluted. Among the estimated heavy metals concentration in the fish muscles only silver (Ag) concentration is less than the permissible concentration. The concentration of (Cr) is about the permitted level, while concentration of Cd, Hg and Pb is twice as much as the permissible concentration. The fishes of the Caspian Sea are polluted with certain concentration of Zn and Cu. Fe and Mg are the most dominant toxic pollutants found in muscles of most of the fishes. Invertebrates: concentration of heavy metals in invertebrates is much less than that of the fishes. Compared to fishes, the average concentration of heavy metals in invertebrates is 100 times less than that of the fishes. Invertebrates play an important role in the marine food chain. Therefore, accumulated heavy metals in the invertebrates could possibly be transferred to the higher trophic level of the food chain. Further detailed studies focusing on the determination of other pollutant concentration of invertebrates are required. Sediments Heavy metals concentrations were measured in rivers, Anzali wetland and the Caspian Sea sediments. Rivers of the Caspian Basin have various degrees of heavy metals concentrations, are directly proportional to the distance from the steel factories or mines situated on the bank of rivers. Sediments of the Anzali wetland are considered highly polluted due to their high concentration levels of Hg, Cr, Pb and Zn. As far as other heavy metals concentrations are concerned, they could be classified as little contaminated or un-polluted. Water The waters of Sefid-rood River and Anzali wetland were investigated for any heavy metals concentration. Results showed a low concentration of heavy metals compared with the standard limit (WHO,1984). This indicated that these waters could be classified as un-polluted. Further investigations are needed in this regard. B. Non-Point Sources These types of pollution sources comprises of agricultural effluents and pollutants, divided into two groups: A) Chemical fertilizers and B) Pesticides Chemical Fertilizers Nitrates and Phosphates are the main components of most chemical fertilizers used in Iran. Sixteen percent of the total fertilizers (national consumption) are used in the northern provinces of Iran, Gilan and Mazandaran. In Gilan, 51,553 tons of fertilizers were used in 1996, out of which urea constituted 61% .The amount of fertilizers used in Mazandaran was 19,0217 tons in the same year, out of which ammonium phosphate constituted 52% (Table 14). During 1996, 241,770 tons of fertilizer was used in the northern provinces of the IR-Iran, of which Urea has been the most commonly used (48%). Pesticides In recent years, the use of pesticides has increased as a result of agricultural intensification in Gilan and Mazandaran provinces. According to "W.H.O", 3.2% of the authorized pesticides used in Iran are considered as extremely dangerous, 11.8% of these pesticides are classified as seriously poisonous and 24.7% are semi dangerous. Statistics indicate that in 1996, eight groups of pesticides have been used in solids and liquids, and only one type was used in evaporates form. In 1996, a total of 2,935,726 litters of liquid pesticides and 2, 591,062 kg of solid pesticides were used in these two provinces, herbicides ( 43%) and insecticides ( 74%) were the most commonly used chemicals. In Gilan Province alone, a total of 914,942 litters of liquid pesticides (insecticides 83%) and 638,426 kg of solid pesticides (insecticides 63%) were used. In other words, 62.2 litters of chemicals were used in each square km of Gilan , out of which 43.4 kg was in solid form. In Mazandaran province also a total of 2,020,784 litters of liquid (insecticides 38%) and 1,952,662 kg of solid pesticides (insecticides 71%) were consumed during the same period. This means that in each km2, 45.3 litters of liquid and 43.8 kg of solid pesticides have been used (Table 29). According to these data, it can be seen that in the whole coastal region, an average of 26.8 litters of liquid and 43.6 of solid pesticides have been used in each km2. The type of pesticides used in the country is shown in table 30. The following results were obtained from a survey carried out in Gilan and Mazandaran provinces regarding the input of pesticides due to agricultural activities along the Caspian coastal region. Seasonal variations and yearly fluctuation of pesticides used including, D.D.T, A.L.D, M.C, M.O.C and H.C.H, were detected in this survey. Astara station indicated the highest level and the most commonly used pesticides were, Aldrine, H.C.H (Beta) as well as, H.C.H (Delta + Gama) in lower concentrations. Summer and winter seasons showed highest and lowest level of pesticide respectively. Astara and Ghare-soo rivers had the highest level of pesticides concentration. HCH was the most common pollutant and Di-Aldrine the least common pesticide used. The average concentration of pesticides indicates that waters in Gilan are more polluted as compared to waters of Mazandaran and : HCH isomers, total HC, total Aldrine and DDT were the most commonly used pesticides. In Fig.18 and table 30, the amount and the distribution of chlorinated pesticides are shown. According to the available data, each year more than 24 tons of chlorinated pesticides are carried into the southern Caspian basin by the inflowing rivers. (Table 31) These are the residue of the pesticides sprayed over the farmlands, orchards and other agricultural lands. The sprayed pesticides are broken down to less dangerous compounds and eventually are carried to the sea. Amongst ten rivers studied, Sefid-rood was found to contain more than 50% of all different types of pesticides under study. This is mainly due to the vast surface area of the Sefid-rood basin and the discharge of farmlands and rice paddies, into the basin. Therefore, most of the insecticides used in these farms eventually find their way to the sea (Table 31, Figure 19). Other than this river, three other major rivers; namely as Astara, Chaloos and Babol-rood, carry the highest amount of pesticides discharge into the sea. On the other hand, the least amount of chlorinated pesticides is found in Nashta-rood and Sardab-rood basins. Concentrations of the pesticides do not vary greatly, from west to east as pesticides are also heavily used in the western region. The 60.7% (maximum) of the total HCH pesticides used in the region have been found in the Sefid-rood region, but only 2% (minimum) in Nashta-rood (Table 30). Sefid-rood also possesses the highest concentration of D.D.T (49%), and Sardab-rood the lowest D.D.T concentration level that is only 0.4% of the total. Aldrine (ALD) concentration also happens to be the highest in Sefid-rood (46.2%) and lowest in Sardab-rood (0.1%). The other two pesticides (MOC and HC) are also found to have their highest quantity in Sefid-rood with 92.3% and 65.8% respectively, and in the lowest quantity in Ghareh-Soo (0.2%) and Sardab-rood (0.3%). It could be concluded that among the 5 surveyed rivers, the highest load of pesticides belong to Sefid-rood river and the lowest to Sardab-rood (while it passes through the mountains before reaching the sea). |
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