Heavy metal accumulation during the last 30 years in the Karnaphuli River estuary, Chittagong, Bangladesh

Abstract

Heavy metal contamination of aquatic environment has attracted global attention owing to its abundance, persistence, and environmental toxicity, especially in developing countries like Bangladesh. Five heavy metals, namely chromium (Cr), copper (Cu), nickel (Ni), lead (Pb) and zinc (Zn) were investigated in surface and core sediments of the Karnaphuli River (KR) estuary in Chittagong, Bangladesh, in order to reveal the heavy metal contamination history in estuarine sediments and its response to catastrophic events and human activities. The surface sediment was predominantly composed of silt and sand, and the surface sediment was contaminated with Cr and Pb. Based on the 210Pb chronology, the sedimentation rate in the inter-tidal zone of KR estuary was 1.02 cm/a before 2007, and 1.14 cm/a after 2008. The core sediment collected from 8 to 20 cm below the surface mainly originated from terrestrial materials induced by catastrophic events such as cyclone, heavy rainfall and landslides in 2007 and 2008. The values of contamination factor (CF) showed that the sediment became moderately contaminated with Cr and Pb in the last 30 years. The variation and accumulation of heavy metals in core sediment before 2000 was mainly related to natural variations in sediment sources; however, in subsequent years, the anthropogenic inputs of heavy metals have increased due to rapid physical growth of urban and industrial areas in the Chittagong city. In general, the accumulation pattern of heavy metals after normalization to Aluminum in sediments of KR estuary indicated an accelerated rate of urbanization and industrialization in the last 30 years, and also suggested the influence of natural catastrophic event on estuarine environment.

Geochronological and spatial distribution of heavy metal contamination in sediment from Lake Naivasha, Kenya

“…Putyrskaya et al (2015) had also observed cases where 210 Pb activity was maximum in subsurface layers for sediment cores collected in Lakes Brienz, Thun, Lucern and Prealpine Lake Meggione of Switzerland. A similar observation had been made by Wang et al (2016) where they assesed sedimentation rate using 210 Pb chronology on Karnaphuli River estuary, Chittagong, Bangladesh.…”

“…The number of times heavy metal concentration in the sediment exceeded the background concentration was determined using the CF. In calculating the CF, Equation 1 was used as presented by El-Sayed, Moussa, and El-Sabagh (2015) and Wang et al (2016).…”

“…Investigations of geochemical changes with depth can be used in determining sediment contamination and, in cases where sedimentation rates are known, changes in contaminant loading with time can be assessed . Changes in sediment contamination with depth also aids in studying the impacts of anthropogenic activities on aquatic system (Wang et al, 2016;Zanjani-Jamshidi & Saeedi, 2017). The sediments can also be used in understanding the spatial and seasonal variation of contaminant concentration levels (Lau & Chu, 1999).…”

Vibrio and Bacterial Communities Across a Pollution Gradient in the Bay of Bengal: Unraveling Their Biogeochemical Drivers

“…In the last decades, Chittagong metropolitan area has experienced a considerable population growth and nowadays comprises of more than 4 million inhabitants. As it occurs in most of the coastal cities of Bangladesh, Chittagong has insufficient water treatment facilities and the effluents from diverse sources are discharged practically raw in the estuary endangering ecosystem and public health (Wang et al, 2016). The lack of safe drinking water and sanitation, and the prevalence of waterborne diseases are key challenges for Chittagong's authorities and stakeholders (Lara et al, 2009).…”

Đánh giá sự tích lũy và rủi ro sinh thái một số kim loại nặng trong trầm tích mặt khu vực hạ lưu sông Đáy

“…Kết quả hàm lượng kim loại nặng trong trầm tích sông Đáy khá tương đồng với hàm lượng kim loại nặng trong trầm tích sông Korotoa, Bangladesh (Pb: 36 ÷ 83; Cu: 35 ÷ 118; Cd: 0,26 ÷ 2,8; Cr: 55 ÷ 183 mg/kg trọng lượng khô) [11] hay cửa sông Karnaphuli, Bangladesh (Pb: 23,66 ÷ 25,05; Cu: 20,34 ÷ 33,06; Cr: 77,0 ÷ 99,8 mg/kg trọng lượng khô) [12] Tuy nhiên, hàm lượng kim loại nặng trong trầm tích sông Hindon, Ấn Độ (Pb: 27,56 ÷ 313,57; Cu: 21,7 ÷ 280,33; Cd: 0,29 ÷ 6,29 mg/kg trọng lượng khô) cao hơn nhiều so với hàm lượng các kim loại này tại khu vực hạ lưu sông Đáy. Quá trình công nghiệp hóa và gia tăng dân số nhanh tại lưu vực sông Hindon là nguyên nhân gây ra sự tích lũy kim loại nặng tương đối cao trong trầm tích sông Hindon [13].…”