Spatial distribution of total petroleum hydrocarbons in the seawater and sediment of Southeast coast of India

Abstract

The spatial distribution of Total Petroleum Hydrocarbons (TPH) were analyzed in the seawater and sediment samples collected from 27 locations along the Southeast coast of India. A rst-time assessment study was carried out on the distribution of TPH in both water and sediments for the entire coastline of Tamil Nadu. The concentration of TPH in seawater showed large spatial variation ranging from Below Detection Level (BDL) to 47.5μg/L and 0.01 to 53.12μg/L in the surface and bottom waters, respectively. TPH levels exceeded the regulatory limits speci ed by FAO, China's Marine Monitoring Standards and the European Community in the seawater samples of Thoothukudi harbour (S2 station). TPH values in sediment were between 2.33-30.07μg/g and their levels remained below the Marine Sediment Quality Standard (500μg/g). The results showed that seawaters of southern stations were comparatively more polluted with TPH. The spatial pro le of TPH in sediments were contrasting to that observed for seawater. Higher TPH values were observed in the northern region than southern. TPH contents showed a nity to clay and silt with a strong positive correlation with clay (R2=0.776; P<0.001), silt (R2=0.648; P<0.001) and negative correlation (R2=0.753; P<0.001) with sand. ANOVA analysis demonstrated a signi cant difference (F=11.75; p<0.01) between the TPH concentrations of water and sediments. Non-metric multidimensional scaling (nMDS) was performed to determine the similarity among sampling stations that formed ve crusted groups. Sediment along the southeast coast can be categorised as slightly polluted with respect to TPH as per the ATSDR standards.