Environmental Impact Assessment of some Gas Field Waste Disposal Zones in Bangladesh by Environmental Indicators

Abstract

Heavy metal accumulation in sediments and soils near industrial and energy production zones is receiving increased attention from recent studies. In Bangladesh, rapid industrialisation and energy extraction are intensifying environmental contamination risks within surrounding ecosystems. Limited studies exist on the elemental composition of both surface environmental samples and deep gas reservoir core samples in Bangladesh, particularly regarding the potential contamination transfer from subsurface formations to the surface environment. The objective of this study is to assess the concentration and distribution of toxic elements in gas field environmental samples and reservoir core samples in Bangladesh. A study of probable contamination of 15 elemental abundances from gas reservoir-well to surrounding environment of Saldanadi and Fenchuganj gas fields was conducted using the EDXRF technique. Seventeen samples, including nine environmental soil/sediment and eight gas well core samples from the two gas fields in Bangladesh, were collected for elemental analysis. Environmental contamination was assessed using enrichment factor (EF), geo-accumulation index (Igeo), and contamination factor (CF), with upper continental crust values as baseline data. High contamination factor values, severe enrichment and moderate to heavy geo-accumulation for average elemental abundance of both As and Pb in soil and sediment samples were found in both gas fields, except for a very high Pb (1675ppm) concentration in one soil sample location, where used-up batteries of vehicles of Saldanadi gas field were also dumped. Well-core samples data revealed that gas-abstraction can be contaminated more by toxic metals/metalloids, suggesting considerable risks.