Heavy metals in afforested mangrove sediment from the world's largest delta: Distributional mapping, contamination status, risk assessment and source tracing

• Published in: Marine pollution bulletin 2024-06, Vol.203, p.116429-116429, Article 116429
• Main Authors: Rahman, Md Saifur, Rahman, Moshiur, Jolly, Yeasmin N., Hossain, Md Kamal, Semme, Sanjida Afrin, Paray, Bilal Ahamad, Arai, Takaomi, Yu, Jimmy, Hossain, M. Belal
• Format: Article
• Language: English
• Subjects: Contamination; Distribution; Ecological risk; Environmental Monitoring; Geologic Sediments - chemistry; Heavy metals; Mangrove sediments; Metals, Heavy - analysis; mHQ; Risk Assessment; Seasons; Water Pollutants, Chemical - analysis; Wetlands
• ISSN: 0025-326X; 1879-3363
• DOI: 10.1016/j.marpolbul.2024.116429

This study aims to assess seasonal and spatial variations, contamination status, ecological risks, and metal sources (Ni, Pb, Cr, Cu, Mn, and Zn) in human-afforested mangrove sediments in a deltaic region. Five sampling locations were sampled during dry and wet seasons. Heavy metal concentrations followed the order: Mn > Zn > Ni > Cr > Cu > Pb. Metal loads, except Cu and Pb, were higher during the dry season, aligning with national and international recommendations. Sediment quality guidelines, contamination factor, geoaccumulation index, enrichment factors, and pollution load index indicated uncontaminated sediment in both seasons. Potential ecological risk assessment showed low risk conditions in all sites. However, modified hazard quotient indicated moderate pollution risk from all metals except Pb. Analysis suggests anthropogenic sources, particularly evident near shipbreaking yards in Sitakunda. While initially uncontaminated, ongoing metal influx poses a potential risk to mangrove ecosystems. [Display omitted] •Mean metal levels: Mn > Zn > Cu > Ni > Cr > Pb, all below recommended levels.•Ship-breaking sites (Sitakundu) and dry season correlated with higher metal levels.•Common indices indicated uncontaminated area, yet mHQ showed low to moderate pollution.•Ecological risk currently low, but ongoing metal input poses potential threats.