HEAVY METAL POLLUTION LINKED TO OIL AND GAS OPERATIONS IN KARAK, PAKISTAN

Abstract

Oil and gas exploration releases large volumes of drilling waste that often contain toxic heavy metals, posing serious risks to surrounding ecosystems and communities. This study investigated the concentrations of arsenic (As), cadmium (Cd), lead (Pb), mercury (Hg), cobalt (Co), and copper (Cu) in drilling waste (9 samples), soils (36 samples), and drinking water (57 samples) collected around the Nashpa oil and gas plant in Karak, Pakistan. Samples were digested and analyzed using atomic absorption spectrophotometry, and the results were compared against international (WHO, FAO, EPA) and national (Pak-EPA, NEQs) standards. All measured heavy metals exceeded permissible limits in at least one medium. Soil samples showed particularly high enrichment of Cd (36.5 mg/kg), As (60 mg/kg), and Hg (28.5 mg/kg), while drinking water samples contained elevated Hg (13.5 µg/L), Cd (8.15 µg/L), and Cu (362.7 µg/L), far above WHO guidelines. Correlation analysis indicated that drilling waste discharges are the primary source of contamination, with clear pathways into both soil and groundwater. The contamination hierarchies were Cd > Hg > As > Cu > Pb > Co in soils and Hg > Cd > Pb > As > Co > Cu in water. These findings confirm that oil and gas activities in Nashpa have resulted in substantial environmental contamination, with potential risks of bioaccumulation and human exposure via water and agriculture. The study underscores the urgent need for improved waste management practices and regular environmental monitoring to safeguard soil fertility, water quality, and public health in the region.