Concentration oj Petroleum Hydrocarbons in Seawater of Gujarat Coast

Transcription

1 Concentration oj Petroleum Hydrocarbons in Seawater of Gujarat Coast

2 3.1 Introduction India has got a coastline of around 7517 kms. Out of which Gujarat occupies around 1663 kms among all the littoral states of the country. (Ref. Commissionerate of Fisheries (1996) Gujarat Fisheries statistics ). The state comprises of three distinct coastal zone viz,. Kachchh, Saurashtra and main land Gujarat. It has got two Gulfs, Gulf of Kachchh and Gulf of Khambat. The main threat to th~ ecosystem of the Gujarat coast is oil spills, petrochemicals and allied industries. The gulfs are being developed as an oil importing bases because of its close proximity to the oil exporting countries of the Middle East. At present the coastal oil refinery facilities are located at, crude oil terminal of Vadinar and Salaya - Mathura pipeline of Indian Oil Cooperation; Reliance petroleum and ESSAR Oil refinery at Motikhavdi and Jam khambhaliya. Together, they targeted to process 39 Million tones (MT.) of crude oil per annum. Gujarat comes into the prime list of fish producing states in the whole country. 25% of the marine fish landings and 15% in export earnings from fisheries comes from the Gujarat state. The increasing output from commercial fisheries as well as increasing output of processed, value added, fishery products in Gujarat, has resulted in increase of shipping activity on the whole Gujarat coast. This shipping activity has increased in the recent years, it is heavy on Okha and Verval coast. In addition to these, due to the vast coastline of Gujarat small and big industries have come up on these coasts. Some of these, industries have developed big and small jetties to export large amounts of oil. This also includes to the oil pollution along with the release from the industries. In India along the central west coast, traces of oil pollution were first recorded in 1971 (Nair et at., 1972). Dwivedi and Parulekar, (1974) investigated the seasonal 33

3 nature and accumulation of oil pollution along the west and east coastline of India. Along the Gujarat coast, oil pollution and its possible sources has been reported by Dwivedi et al., (1974). They have reported tar balls on the beaches of Gujarat from Porbandar, Odedar, Cosabara, Veraval, Prabhasputtam Somnath and Dumas Surat. These workers have not quantified the petroleum hydrocarbon in seawaters from the Gujarat Coast. However, Department of Ocean Development New Delhi, had launched a project entitled "Coastal Ocean Monitoring and Prediction System", under this project concentration of petroleum hydrocarbons was determined from different depth and distances from the shoreline at various locations on Gujarat coast. Data on concentration of petroleum hydrocarbon in the intertidal area of Gujarat coast is lacking. Therefore, this study was undertaken with a view to monitor the contamination of petroleum hydrocarbon in the seawater of intertidal region of Gujarat coast, where the oil pollution is frequent and intense. 34

4 Following are some details of oil spills recorded on Indian C0ast. (Source: Indian Coast Guard's report) Date Nature Qty. Oil Spill Position 7'h Sept tons fuel oil Gulf of Manner 14th Nov.91 40,000 tons crude oil Bombay High 16 th Apr tons Crude oil 54 NM West Kochi 16 th Aug tons Kerosene Madras Harbour NOV tons fuel oil Mumbai Harbour Jan.93 40,000 tons Off Nicobar Island Apr tons crude oil Mumbai Harbour May tons fuel oil Bhavnagar Ii" May tons crude oil Mumbai High t W Aug tons Fuel oill Diesel Off New Mangalore I st Oct ton Crude Oil Kochi Harbour 21 stmay tons crude oil Off Saccramento Pt. 5 Ul Jun tons crude oil OFF Auguda Goa 20 th Jul tons Fuel Oill Diesel Mumbai Jawahar Island 27th Nov tons Fuel Oill Diesel Off Mumbai 26 th Mar tons Diesel OffVizag 21 st May tons Fuel Oill Diesel Off Hoogly River 16 th Jun Tons Fuel Oill Diesel Off Prongs 18 th Jun Tons Fuel OillDiesel Off Bandra 18 th Jun Tons Fuel OillDiesel Off Kalaja 16 th Aug Tons Fuel OillDiesel Off Malabar Coast 14 th _ 18 th Jul tons Fuel Oill Diesel Mul Dwarka 19 th Jul Sagar Lt 22 NM 17 Ul Dec.02 I ton -- 8 UlJun tons Vadinar 35

5 Information regarding commercial ships at Vadinar Off shore oil terminal. (Source: Superitending Engineer Offshore oil terminal Vadinar) Year Total Number of Lakh Mt of Oil tankers Crude oil handled Sampling locations Eight transects, Alang and Mahuva in Gulf of Cambay, Vadinar and Kandla in Gulf of Kachchh while Veraval, Porbandar, Dwarka, and Okha in Arabian sea have been selected for the present study. The location map of all the sampling transects is presented in Fig > Alang (21 20'N, n 0 12'E) It is biggest ship breaking yard of Asia. Petroleum hydrocarbon, heavy metal, paint scraps, plastic materials and domestic sewage pollute its water. Due to ship breaking activities, most of the heavy metals like iron, manganese, copper, lead, cadmium and mercury are found in seawater and sediments. Samples were collected from the plot during the ship breaking activity was In progress. > Mahuva ( 'N, TE) It is situated at mouth of the Gulf of Cambay. The water is highly turbid. It is a port town, many small salt manufacturing units are located near by this place, but the oil pollution is very low. Therefore it was considered as control site in the present study. 36

6 GUJARAT Porbandar 8 Arabicn 7 diu Sea J 7 Fig.3.1 Sampling locations > Vadinar ( 'N, 'E) It is a biggest port for handling petroleum crude oil. It is an important offshore oil terminal and it handles crude on account of Mis. Indian Oil Cooperation. The crude oil from this port is pumped to various refineries in the inland areas. A fertilizer manufacturing industry discharges its effluent in the near vicinity of this area. This transects is ecologically important, since it falls under ecologically sensitive, biodiversically rich marine natural park and sanctuary (MNP&S). The core area of MNP&S is Pirotan Island which is nearer to this transect. In this transect, the samples were collected from the port area. > Kandla ( 'N, 'E) It is a free trade zone and biggest harbor on the Gujarat coast. It handles big cargo ships, carrying fertilizers, chemicals, petroleum products, food grains etc. The perennial big rivers of Pakistan discharge their waters 37

7 in the gulf region. The seawater is highly turbid throughout the year. In this transects the samples were collected from the harbor area. > Vera val ( 'N, 'E) It is one of the important port cities in Saurashtra region. Fish processing industry, domestic sewage and viscous yarn industry pollutes its water. The increase in number of fishing boats, their maintenance activity along with untreated waste water from industrial and urban area is directly discharged into harbor and near by coast causing severe damage to the aquatic environment to this area. It has been observed that Veraval harbor is one of the most degraded water body along Gujarat coast. Sampling was carried out form harbour area. > Porbandar (21 37'N, 'E) It is a port town and has got a big chlor-alkali industry whose effluents are discharged in to the sea. Some area of the coast is also polluted by domestic wastewater discharge and port activities. The sampling was done near the vicinity of the port. > Okha ( 'N, 'E) It is a second biggest port of Gujarat state. It handles petroleum products, fertilizers, mineral ores, cement and marine chemicals etc. It is famous for its biodiversity of marine flora and fauna. Effluent of chlor alkali industry is discharged in this region. The port region was ideal for sampling for this transects. > Dwarka ( 'N, 68 0 S6'E) It is a pilgrim town, domestic sewage and fisheries wastes pollute its waters. This transect is famous for fishing activity, about 2000 small and big fishing boats are in operations in this port and due to this coastal waters are highly contaminated with petroleum hydrocarbon. It is famous for its marine flora and fauna. The samples were collected from Rupen Bandar of Dwarka, where heavy fishing and shipping activity is observed. 38

8 Chapter Materials and Methods Several workers have used different methods to estimate petroleum hydrocarbon from the seawaters. The most commonly used method is of GC-MS and UV fluorimetry (UVF). In this study the UV fluorimetry method has been used as it is simple, sensitive and easy to apply. Seawater samples were collected from each locations from intertidal area during high as well as low tide. The sampling was carried out six times in a year, twice during December - January 2002, second in April - May and third in July - August. The surface seawater samples were collected using clean plastic buckets, samples were kept in clean and amber coloured glass bottle for further analysis in laboratory. Seawater samples (2.5 lits.) were extracted with 25 ml of Hexane or n-hexane in separating funnel. A vigorous shaking was given and then was allowed to stand for nearly an hour. The organic layer was separated after about one hour. This extraction was repeated for three times. The extract was dried over anhydrous sodium sulphate and rotary evaporated to nearly dryness under reduced pressure at 30 0 C. Then it was taken in 10 ml Hexane. The fluorescence of the concentrate extract was measured at 365 nm excitation and at 310 nm emission, with crysene as the standard using Perkin - Elmer LS 50 Luminescence Spectrometer (Mandalia, 1999). For standard, the stock solution of 10 J,J.g mrl of crysene was prepared. The working standard solution was prepared by dilution of I ml of stock solution to 100 ml with hexane. In all the preparations the Hexane used was of HPLC grade. This solution was used to make five level calibration curve. The data are presented in J,J.g rl. 39

9 3.3 Results and Discussion The concentration of petroleum hydrocarbon in seawater at different locations on Gujarat coast during the year 2002 are presented in table 3.1 and maximum, minimum and mean value is given in table 3.2. The annual mean concentration of petroleum hydrocarbon at each transects is depicted in fig.3.2. The petroleum hydrocarbon concentration ranged from non-detectable quantity at Mahuva during December January 2002 to j.lg rl at Alang during April-May The annual mean concentration varied from 0.66 j.lg rl at Mahuva to 86.26j.lg rl at Alang. The concentration of petroleum hydrocarbon was maximum at Alang (86.26j.lg rl), it declined towards south to almost non-detectable limit in Mahuva (0.66j.lg rl) which is approximately 40 kms away from Alang. It again increased at Veraval (7.32j.lg rl) and decreased at Porbandar (5.13j.lg rl). High increase of petroleum hydrocarbon concentration was seen in Dwarka (16.79j.lg rl) and again declined at Okha (4.90j.lg rl). Towards Gulf of Kuchchh, the concentration increased from Okha to Vadinar (16.21j.lg rl) and decreased at Kandla (14.18j.lg rl). Alang showed highest concentration throughout the year during both high as well as low tide in comparison to all the other transects. It varied form j.lg rl to j.lg rl during the study period. The high concentration may be due to the ship breaking activity at this location, mainly in the intertidal area. 40

10 Table 3.1 Concentration of Petroleum hydrocarbons in seawater at different locations on Gujarat coasts Location Dec-Jan 2002 April-May 2002 July - Aug 2002 Low Tide SoV High Tide SoV Low Tide SoV High Tide SoV Low Tide SoV High Tide SoV ialang ± ± ± ± ± lmahuva N.D N.D N.D N.D N.D 1.01 ±O.71 Iveraval ±I.OO ± ± IPorbandar ± ± ± ± Dwarka ± ± ± ±O.45 Okha ± ± ± Vadinar ± ±1.I ±1.I ± ± Kandla ± ± u 9.78 ±1.05 All the values are in Ilg ]"1. S.V.: Sample variation. N.D: Non-detectable limit. 41

11 Table 3.2 Maximum, Minimum and Mean values of Petroleum hydrocarbon at different locations on Gujarat coast in the year 2002 Low tide High tide Locations Maximum Minimum Maximum Minimum Mean Mean value value value value Alang Mahuva N.D N.D Veraval Porbandar Dwarka Okha Vadinar Kandla All values are in llg rl. NO: Non-detectable limit. 42

12 <.i c 0 60 u '" :c Q., Locations Fig.3.2 loti Alang 5. N;h' Dwarka Annual mean concentration ofphc at different location along Gujarat coast 2. Mahuva 3. Veraval 4. Porbandar 6. Okha 7. m Vadinar 8.m Kandla The concentration of ls)lg rl and above was observed at Kandla, Vadinar and Dwarka whereas in Veraval, Porbandar and Okha, the concentration was below IO)lg rl through out the year. The high concentration of petroleum hydrocarbon in Kandla and Vadinar is due to shallow and enclosed nature of the basin. Moreover after unloading cargo at the receiving port, the ships become light and they become difficult to handle. It is a general practice to fill the tanks with seawater. Now, when the tanker is unloaded it 43

13 cannot be completely cleaned because some oil remains on the bottom and sides of tanks. This water mixes with ballast waters and is later discharged as ballast water. Prevailing high concentration at Dwarka is attributed to intensive fishing activity in this region. The low concentration at Verval, Porbandar and Okha is due to open seacoast where the waves playa great role in dispersing. Due to high turbulence, the mixing of petroleum hydrocarbon in seawater is at very high rate. The concentration of petroleum hydrocarbon was comparatively less during the monsoon period in all the transects. This is due to the decrease in fishing and shipping activities and also due to the prevailing rough weather during this season on Saurashtra coast - Gujarat. Central Salt and Marine Chemicals Research Institute, Bhavnagar (CSMCRI) carried out similar study during the year under Coastal Ocean Monitoring and Prediction System (COMPAS). They studied the concentration of petroleum hydrocarbon in seawater collected from different depths and distance from the shoreline. Fondekar and Alagarsamy,(l984) reported the value of petroleum hydrocarbon along oil tanker route region between Nand E in Arabian Sea. They have observed that the maximum concentration (9.2flg rl) was in surface waters and with increase in the depth the concentration decreased (1.8flg rl) In comparison to the both above studies, it was observed that the concentration of petroleum hydrocarbon is high in the seawater samples collected from the intertidal region, this may be due to the accumulation of petroleum hydrocarbon in this area. However, the trend of variation at each transect is comparable with the data collected under COMPAS project. 44

14 Chapler 3 Oil Spill due to Shipping activity at Rupcn Bandar, Dwarka 45

15 Effect of Petroleum Hydrocarbons on