Seasonal variation, contamination and ecological risk assessment of heavy metals in sediments of coastal wetlands along the Bay of Bengal

Mohammad Belal Hossain; Jakia Sultana; Yeasmin N Jolly; As-Ad Ujjaman Nur; Salma Sultana; Rubel Miazee; M Saiful Islam; Bilal Ahamad Paray; Takaomi Arai; Jimmy Yu

doi:10.1016/j.marpolbul.2023.115337

Seasonal variation, contamination and ecological risk assessment of heavy metals in sediments of coastal wetlands along the Bay of Bengal

Mar Pollut Bull. 2023 Sep;194(Pt B):115337. doi: 10.1016/j.marpolbul.2023.115337. Epub 2023 Jul 27.

Authors

Affiliations

¹ Department of Fisheries and Marine Science, Noakhali Science and Technology University, Noakhali 3814, Bangladesh; School of Engineering and Built Environment, Griffith University, Brisbane, QLD 4111, Australia. Electronic address: belal.hossain@nstu.edu.bd.
² Department of Fisheries and Marine Science, Noakhali Science and Technology University, Noakhali 3814, Bangladesh.
³ Atmospheric and Environmental Chemistry Laboratory, Chemistry Division, Atomic Energy Centre, Dhaka 1000, Bangladesh.
⁴ Department of Zoology, College of Science, King Saud University, PO Box 2455, Riyadh 11451, Saudi Arabia.
⁵ Environmental and Life Sciences Programme, Faculty of Science, University Brunei Darussalam, Jala Tungku Link, Gadong BE 1410, Brunei Darussalam.
⁶ School of Engineering and Built Environment, Griffith University, Brisbane, QLD 4111, Australia.

PMID: 37516095
DOI: 10.1016/j.marpolbul.2023.115337

Abstract

Functioning of coastal wetland habitats is essential for the ecosystem integrity and sustainability of coastal development that enables human progress along transitional waterways. However, these habitats are continuously being affected by a variety of pollutants including metallic elements. In this study, seasonal variation, pollution status and ecological risks of heavy metals (Cr, Mn, Co, Ni, As, Cu, Zn and Pb) in surface sediment of the several types of coastal wetlands (estuaries, mudflats, sandy beaches, mangroves, and saltmarshes) were detected by using X-ray fluorescence (EDXRF) spectrometry. The results showed that the mean concentration level of metals in the surficial sediment samples followed the order of Cu (84.06 ± 8.60 μg/g) > Zn (51.00 ± 8.97 μg/g) > Mn (38.25 ± 11.34 μg/g) > Cr (3.52 ± 0.91 μg/g) > Pb (0.27 ± 0.13 μg/g) > Co (0.24 ± 0.13 μg/g) > As (0.21 ± 0.12 μg/g) > Ni (0.16 ± 0.08 μg/g). In comparison to the pre-monsoon period, the post-monsoon season had higher concentrations of heavy metals while the overall accumulation level of metals in the wetlands exhibited a pattern of estuarine wetland (28.47 ± 31.35 μg/g) > mangrove (22.23 ± 30.79 μg/g) > mudflat (21.79 ± 29.71 μg/g) > sandy beach (21.47 ± 28.15 μg/g) > saltmarsh (21.28 ± 30.02 μg/g). Although, the pollution assessment indices e.g., contamination factor (CF), degree of contamination (CD), geoaccumulation index (I_geo) and pollution load index (PLI) showed minimal levels of contamination in the studied sites, enrichment factor (EF) suggested greater enrichment of the metals in the pre-monsoon season but with the lowest ecological risk (RI < 40) in both seasons. Cluster analysis, principal component analysis (PCA), and Pearson's correlation were performed to determine the sources of heavy metals in collected samples which specified that Pb, As, Co and Ni predominantly came from natural sources whereas Cu, Mn, Zn and Cr emerged from anthropogenic sources such as industrial effluents, domestic wastewater, fertilizer or pesticide consumption on farmland along the riverbank, vessel emissions, and the confluence of tributary rivers.

Keywords: Coastal wetlands; Contamination; Ecosystem services; Heavy metal; Risk assessment; Seasonal variation.

MeSH terms

Bays
Ecosystem
Environmental Monitoring / methods
Geologic Sediments / chemistry
Humans
Lead / analysis
Metals, Heavy* / analysis
Risk Assessment
Seasons
Water Pollutants, Chemical* / analysis
Wetlands

Substances

Lead
Metals, Heavy
Water Pollutants, Chemical