PANAJI
Coastal sediments of Goa, a tourist hotspot known for its beaches, are found to be heavily contaminated with polycyclic aromatic hydrocarbons -- produced from coal burning, oil or petroleum spillage --which can cause harmful effects to the ecosystem.
The study published by National Institute of Oceanography (NIO) has stressed on the need to put in place preventive protocols considering the “extremely high” toxic effect on the ecology.
The study “Risk assessment of polycyclic aromatic hydrocarbon (PAH) infested sediments along the coast of Goa”, undertaken by NIO scientists Vasudha C Bhatawadekar, Samir R Damare and Anita Garg, reveals that the total concentration of PAHs along the Goa coastline was 1.00 to 875 pg g−1, with maximum PAH concentrations detected in the Divar island mangrove (875 μg g−1) and the least was observed at Galgibaga beach (365 μg g−1).
“Source apportionment of PAHs was analysed based on diagnostic ratios and results exhibited that petroleum products and their combustion were primarily responsible for their generation,” the study concluded.
“The PAH contamination in the sediments collected from the Goa coastline and rivers falls in the category of high-priority risk and can cause harmful effects to the ecosystem. The toxic effects of PAH contamination on the ecosystem in the Goa coastline are extremely high. The risk quotient values from all the samples call for the need for preventive protocols to be put in place to lower the PAH concentration,” it added further.
Experts said that PAHs are priority organic pollutants and they are produced from coal, oil, natural gas combustion, and petroleum spillage. Accidental oil spillage and fuel burning during transport may lead to the generation and accumulation of PAHs in the sediment, they said further.
“Amongst many other pollutants, PAHs represent a major class of contaminants owing to their widespread distribution and protracted environmental persistence,” the study said.
The sediment samples were collected using sediment grab from coastal regions of Mandovi estuary, Zuari estuary, Sal River, Galgibaga beach, and Divar Mangrove Island. The sampling locations were selected based on the possible oil seepage during the movement of cargo ships, ferry boats, fishing trawlers, and anchored floating casinos at Zuari estuary and the mouth of Mandovi estuary.
The study aimed to establish a baseline for PAH concentrations in the sediments along the shoreline to help comment on the pollution levels caused and thereby understand the risk and their impact on the marine life therein.
ZUARI ESTUARY: The sediments obtained from the Zuari estuary showed that the source of PAH is majorly due to petroleum combustion, and at some sites, it showed petrogenic (refers to the PAHs that emerged due to the influence of petroleum and crude oil or fossil fuel)
The study said that the area records a lot of shipping activities due to proximity to the Port area (MPA, Goa). The cross-plot indicates that the high molecular weight (HMW) PAH and lower molecular weight (LMW) PAH originated from petroleum spillage and combustion in the Zuari estuary.
DIVAR MANGROVE: Sediment samples showing a higher concentration of PAHs as compared to other sites from Goa, exhibited the pyrolytic origin of PAH.
RIVER SAL: The PAH origin was pyrogenic. This could be attributed to the fact that this site has residential interference where chances of coal burning for cooking could be routine practice, which could lead to incomplete combustion and hence generation of PAH. Also, this area sees a lot of ship movements, like ferry boats and fishing vessel movements
MANDOVI ESTUARY: PAH sources were Petrogenic. Transportation of ferry boats, fishing trawlers and refuelling of anchored floating casinos could lead to accidental oil seepage in the water, reaching the sediments.
