Shipping traffic cause of oil slicks in Arabian sea: Study
Shipping traffic is the primary cause of oil slicks in the eastern Arabian Sea, contributing a larger share (1024.8 sq. km) to the oil spills in the region between 2017 and 2020 than those caused by oil fields located at Bombay High off the coast of Maharashtra (843.90 sq. km), a new study by the scientists at the National Institute of Oceanography has revealed.
“It is evident from the data there are three regions where density of oil spills is higher, indicating that these three regions are potential oil spill hot spots along the west coast of India — offshore of Gulf of Kachchh, Gujarat, offshore of Mumbai coast, and offshore between south Karnataka and north Kerala states,” said V Suneel, who oversaw the research.
Eastern Arabian Sea is highly vulnerable to oil pollution due to rigs operating in the region, high shipping activity at west coast ports and international oil tanker routes. Illegal cleaning of oil tankers, pipeline ruptures and dumping of industrial pollutants in the nearshore region add to the catastrophic threat to its marine ecosystem.
The study by Suneel, V Trinadha Rao, and others made use of the freely accessible Sentinel- 1 Synthetic Aperture Radar (SAR) imagery to study year-to-year distribution of oil spills and identify the potential hot spots.
It analysed satellite imagery from 2017 to 2020. The research has been published in the peer-reviewed Marine Pollution Bulletin earlier this year.
Near Gujarat, nearly 52 oil slicks (17.56%) were found in 356.58 sq km between 2017 and 2019.
In offshore Maharashtra, there were 176 oil slicks (59.45%) over 1022.14 sq. km in the same period, and finally, in Karnataka and Kerala, there were 68 oil slicks (22.97%) over 475.92 sq. km area, the study found.
The study found a significant reduction in oil slicks off the Gujarat coast during 2020, which could be due to the nationwide pandemic lockdown that saw a decrease in fishing activity, which the researchers said was further evidence that sea vessels contribute a major portion of the oil pollution.
There was a significant reduction of oil spills (only 4.3 sq. km, accounting for 1.2%) in 2020 compared to other years in areas where ship-based oil spills are dominant, possibly due to pandemic disruptions, the study said.
However, there was no significant reduction in oil spills observed over areas that see oil field based spills (170.29 sq. km, accounting 16.66%) and the international tanker routes (195.01 sq. km, accounting for 40.97%) during 2020.
“This suggests that the ships that ply along the international tanker routes pass through this region may contribute to oil pollution,” researchers said.
“Further study is needed to understand the fate of oil spills occurring in those identified hot spot regions and their environmental consequences.”