Occurrence, distribution and sources of petroleum contamination in reef-associated sediments of the Gulf of Mannar, India

The distribution of saturated hydrocarbons and polycyclic aromatic hydrocarbons (PAHs) was assessed in superficial sediment samples collected from Mandapam island groups, Gulf of Mannar, India. The hydrocarbon distribution pattern and the n-alkane indices (e.g., carbon preference index (CPI) and natural n-alkanes ratio (NAR)) were deployed to differentiate between the biogenic and anthropogenic sources. Petroleum pollution was indicated by the pristane/phytane ratio close to 1. Presence of a prominent unresolved complex mixture (UCM) as well as hopane concentrations further supported this assertion. The evaluation of petrogenic sources of contamination were also comprehended by various diagnostic ratios of PAHs. The sites associated with shipping activities, tourism, and located near the mainland and accessible portions of the islands exhibited high petroleum contamination. Correlation analysis underlines the significance of combining petroleum-specific marker compounds and diagnostic ratios to improve the assessment of human influence on marine ecosystems.

Automated summary

This study assessed the distribution of saturated hydrocarbons and polycyclic aromatic hydrocarbons in sediment samples from Mandapam island groups in the Gulf of Mannar, India. Differentiation between biogenic and anthropogenic sources was achieved using hydrocarbon distribution patterns and n-alkane indices. The results indicate high petroleum contamination in areas associated with shipping activities, tourism, and those located near the mainland and accessible portions of the islands.