Polycyclic Aromatic Hydrocarbons (PAHs) in aquatic ecosystem exposed to the 2020 Baghjan oil spill in upper Assam, India: Short-term toxicity and ecological risk assessment

Abstract

This study focuses on the short-term contamination and associated risks arising from the release of Polycyclic Aromatic Hydrocarbons (PAHs) due to the 2020 Baghjan oil blowout in upper Assam, India. Shortly after the Baghjan oil blowout, samples were collected from water, sediment, and fish species and examined for PAHs contents. The results of the analysis revealed ΣPAHs concentrations ranged between 0.21–691.31 μg L-1 (water); 37.6–395.8 μg Kg-1 (sediment); 104.3–7829.6 μg Kg-1 (fish). The prevalence of 3–4 ring low molecular weight PAHs compounds in water (87.17%), sediment (100%), and fish samples (93.17%) validate the petrogenic source of origin (oil spill). The geographic vicinity of the oil blowout is rich in wildlife; thus, leading to a significant mass mortality of several eco-sensitive species like fish, plants, microbes, reptiles, amphibians, birds and mammals including the Gangetic River dolphin. The initial ecological risk assessment suggested moderate to high-risk values (RQ >1) of majority PAHs concerning fish, daphnia, and algae species. This study highlights the need for recognizing the potential for short-term exposure to local species. To safeguard local ecosystems from potential future environmental disasters, it is imperative for the government to adopt a precautionary strategy.

An Analytical Case Study of the Oil Well Blowout at Baghjan Oil Field, Assam: a Human and Environmental Perspective

“…The Maguri-Motapung Wetland has been severely damaged and polluted, which has resulted in the death of large-scale aquatic animals, including the rare Gangetic River Dolphin. The Polycyclic Aromatic Hydrocarbon (PAH) concentration in the site was signi cantly higher than in other parts of India, i.e., 0.21 to 691.31 μg Kg -1 (V. Singh et al 2023). Because many of these pollutants will leach into the ground and contaminate groundwater, the impact is signi cant and will have lasting repercussions.…”

“…Regarding fauna in Maguri-Motapung Wetland, 35 dead species from 13 families were recorded, with nearly 22 species threatened. PAH concentration reported in sh ranges from 104.3 to 7829.6 μg Kg -1 , with an average value of 1932.37 μg Kg -1 , which samples appear to be 10 to 100 folds higher than in other parts of India (V. Singh et al 2023). They also mentioned that the signi cant increase of the PAHs and low dissolved oxygen are the leading causes of death in different sh species.…”

“…The oil and gas leak also contaminated the soil of nearby agricultural elds, putting the general population at risk. PAH levels in soil range from 37 to 395.8 μg Kg -1 , which is substantially more than acceptable (V. Singh et al 2023). From the preliminary EIA conducted after the killing of the well, the Total Petroleum Hydrocarbons (TPH) concentrations in the Maguri-Motapung Grassland area varied from 32 mg/kg to 736 mg/kg, which is high near the radius and decreased outward (Khandelwal et al 2022).…”

Polycyclic Aromatic Hydrocarbons (PAHs) in Freshwater Systems: A Comprehensive Review of Sources, Distribution, and Impacts

“…While other protected wetlands considered as Ramsar site importance, are degraded by a complex mix of multiple petrogenic and pyrogenic PAHs sources when they serve as the final receiver of river water [158]. The paradigm of PAH mixed sources freshwater urban wetlands near oil exploitation activity, can be easily affected by extraordinary events, like crude oil spills or discharge [159]. Other types of freshwater wetlands are peatlands, marshes, and bogs.…”

Characterization of Microplastics and Adsorbed/Dissolved Polycyclic Aromatic Hydrocarbons in the Biggest River System in Saitama and Tokyo, Japan

“…Because PAHs are persistent, widely dispersed, poorly biodegradable, carcinogenic and mutagenic, and have the propensity to bioaccumulate and biomagnify in food chains, they are important to the ecosystem [ 11 ]. PAHs are often colorless, white, or light-yellow solids that arise spontaneously as compound combinations [ 12 ]. Their lipophilic character makes them extremely soluble in organic solvents, but they have a low vapor pressure, high melting and boiling temperatures, and a very poor aqueous solubility (hydrophobic) [ 12 ].…”