Elevated concentration of selected heavy metals in Gadani shipbreaking area, Pakistan

Abstract

The world's busiest ship-recycling hub, Gadani Beach in Baluchistan, Pakistan, may pollute the environment. This work provides the first complete and geographically resolved assessment of heavy metal pollution in Gadani shipbreaking region coastal sediments. Nine heavy metals were evaluated in 69 sediment samples from the shipbreaking site and a neighboring reference zone. Top 7 cm beach sand and sediments were collected from the yard zone and deconstruction zone at intertidal (0.3 m) and subtidal (2.4 m) depths. Additional sediment samples were taken from reference sites at 1.4–3 m depth. Two yard and dismantling zone replicates, and one reference site replicate were taken at each station. ICP-MS analyzed metals. Geoaccumulation Index and potential ecological risk index (PERI) were used to assess sediment contamination. Geoaccumulation Index and potential ecological risk index (PERI) were used to assess sediment contamination. Metal concentrations were 3–53 times greater in the shipbreaking area than at the reference location. The concentration hierarchy was Fe > Mn > Zn > Pb > Cr > Ni > As > Co > Cd, with Pb, Zn, and Ni above Effect Range Medium (ERM) criteria, implying ecological harm. Spearman correlation and cluster analysis showed substantial inter-metal correlations, indicating shared sources—primarily shipbreaking materials like paints, batteries, anodes, and lubricants. The yard zone was most polluted, followed by the seaward disassembly zone. Sediment Quality Guidelines (SQGs), Contamination Factor (Cf), Geoaccumulation Index (Igeo), and δ¹ ³C isotopic fingerprints identified anthropogenic oil inputs and environmental hazards. This study provides essential baseline data for regional ship recycling regulatory frameworks and environmental management.