The world heritage site Sundarbans is still reeling from the effects of the oil spill, though the pollution level has fallen. The 2014 oil spill severely damaged the life and soil of the Sundarbans. The number of trees, fish, snakes, snails and crabs is going down, creating a detrimental impact on the food chain of the animals there.

This was revealed in a year-long survey run by a team of researchers and headed by Professor Abdullah Harun Chowdhury of the Khulna University environmental science department. According to the survey, the oil is not visible, but it is stuck in every layer of mud and this is damaging the world’s largest mangrove forest. The survey also said the oil level in the effected forest areas is 20 times higher than normal.

On 9 December 2014, the vessel OT Southern Seven capsized in the river Shela, spilling 3.5 lac litres (350 thousand litres) of fuel oil. A long-term risk on marine biodiversity loss was sustained according to a joint research of United Nations and the ministry for environment and forest. However, vessels continued to ply through the Sundarbans.

'The evaluation of environmental hazards of the Sundarbans oil spill and monitoring report-2016’ was done in two parts headed by Professor Abdullah Harun Chowdhury. The first part was from December 2014 till February 2015. The second part was from March 2015 till February 2016. The research was done on both areas affected by the oil spill and the non affected areas of the forest. Assistant Professor Iftekhar Islam of National University zoology department and marine biodiversity expert GM Jaglul Islam were also associated with the research.

Water contained 9 milligrams of oil per litre in the non-affected areas, said the research. However, 43 milligrams of oil was found per litre of water in three places of the affected 300 square kilometre areas which was 1 gram immediately after the incident.

Examining the soil collected two inches deep along the non-affected areas, it was found that per kilogram of soil contained only 5 milligrams of oil, whereas the soil from the affected areas contained 123 milligrams of oil per kilogram. Last year, it was more than one gram.

Prof Abdullah Harun said among the 3.5 lac litres (350 thousand litres) of fuel oil, government managed to remove 1 lakh litres of oil after the incident. The rest of the oil stayed at the water, soil and trees of the forest. The forest department along with other institutions managed to bury some oil in the forest with the help of locals. The oil entered the ecosystem of the forest with a poisonous effect on the biodiversity. However, the amount of oil is decreasing with high and low tides and rain in the forest since last June.

It has been observed that per litre water of the Sundarbans contain 326 plant organisms. The amount was 103 in the affected areas of the forest on last February. Every litre of the water contained 20 to 30 plant organisms immediately after the incident of oil spill.

Usually 53 animal organisms were found in per litre of water in the Sundarbans which is presently 22 and was only 7 immediately after the incident. COD test is done to identify the level of organic material in the water. The test showed the water contained 69 milligrams of COD. 153 milligram was found on last February.

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