Baseline study of water, soil, and identification of potential native phytoremediators of total petroleum hydrocarbon from oil-contaminated areas in the vicinity of Geleky oilfield of Assam

Petrochemical contamination has been one of the significant causes of pollution all over the world. The upper Assam of Northeast India has been known for its oil industries and their contribution to India's economy. With tremendous oil production, an adequate amount of petroleum contamination is also observed. Several works have been furnished in the oilfields of Assam; however, the knowledge of heavy metal contamination and hydrocarbon pollution in nearby water bodies and soil, along with risk assessment and statistical validation in the vicinity of the Geleky oilfield of Sibsagar district of Assam, is still limited. The study also reveals native potential phytoremediators that can uptake heavy metals and hydrocarbons to help clean the environment through a greener approach. The presence of aromatic hydrocarbon derivatives in water, soil, plants, and sludge samples, including groundwater, is an alarming concern due to their high toxicity to the surrounding ecosystem and potential threat to the groundwater system. The Principal Component Analysis (PCA) further corroborates the significant and common origin of the heavy metals and total petroleum hydrocarbon (TPH), which inclines toward the oil exploration activities in the nearby oilfield. Among all the six plant species studied, Colocasia esculenta proved to be a noteworthy phytoremediator of both heavy metals and TPH, having an uptake efficiency of 78% of Zn, 46% of Pb, and 75% of Fe, and 70% of TPH. The study provides baseline information to help us identify future threats and suitable endemic phytoremediators, which can be advantageous for future remediation.