Tracing and source fingerprinting of metals from the southern coastal sediments in Bangladesh.

Trace element pollution from anthropogenic sources is increasingly widespread. This pollution in terrestrial environments threatens agricultural crop production, while in aquatic environments, it threatens fish cultivation. The contamination of these crucial food sources raises significant concerns regarding food safety, security, and its potential adverse effects on human health. Coastal areas are particularly vulnerable to heavy metal pollution due to their proximity to industrial and urban centres, as well as their susceptibility to contamination from marine sources. In attempting to identify the sources of heavy metals (As, Cu, Cr, Cd, Fe, Hg, Mn, Ni, Pb, and Zn) and measure their contributions, we collected soil samples from thirty sites along the three coastal districts (Patuakhali, Barguna, and Bhola) in Bangladesh. Using atomic absorption spectroscopy, heavy metal concentrations in soil samples were measured and three receptor models (PMF, PCA-MLR, and UNMIX) were applied to detect their sources. Pairwise correlation analysis of metal concentrations in 30 sites across 3 coastal districts showed all possible patterns, including both significant and insignificant positive and negative relationships between different metals, except for As and Hg which did not display any significant relationships with other metals. The concentrations of Cu, Fe, Mn, Ni, and Zn exceed the US-EPA sediment quality standard. The applied PCA-MLR, PMF, and UNMIX models identified several sources of heavy metal contamination, including (i) mixed anthropogenic and natural activities: contribution of 59%, 37%, and 43%, and (ii) vehicle emissions: contribution of 23%, 26% and 29%. The recognized metal sources should be prioritised to avoid the discharge of poisonous pollutants from anthropogenic factors and any possible future exposure. This study's findings have implications for ongoing monitoring and management of heavy metal contamination in coastal environments to mitigate potential health and ecological impacts and can inform policy development and management strategies.

Abundance, distribution and composition of microplastics in sediment and fish species from an Urban River of Bangladesh.

Microplastics (MPs) are a growing concern due to its ubiquitous presence and exceptional stability. We examined the abundance, dispersion, and attributes of MPs in the sediment and fish species of the Turag River in Bangladesh, which separated the industrial city Gazipur from the Mega-city Dhaka. Collected samples were digested and the chemical structure was identified using ATR-FTIR spectroscopy. The concentration of MPs in the sediment ranged from 10 to 35 particles kg-1, with a mean abundance of 19.2 ± 2.44 particles kg-1and MPs of the fragment type account for 34 % of all. The majority of MPs were discovered in the 3-5 mm size range. MPs concentrations in freshwater fish gut from the Turag River ranged from 0.63 ± 0.18 to 7.0 ± 1.1 microplastics individual-1. Fiber was found to be the most commonly ingested MPs type (43 %), followed by fragments (41 %), film (12 %), and foam (4 %). The most common type of MPs was transparent (34 %) followed by red (28 %), white (20 %), green (9 %) and black (8 %). The results showed that demersal (1.87 ± 0.39 items individual-1) and benthopelagic (1.5 ± 0.26 items individual-1) fish species had more MPs than pelagic fish (0.63 ± 0.18 items individual-1) species. Polypropylene (PP) was found to be the most dominant polymer type in the sediment sample, and PS (39 %) in the fish sample. Polyethylene (PE) was discovered to be 30 % and PP 25 % in sediment and fish samples, respectively. Other commonly detected polymer types include polyamide (PA), polystyrene (PS), cellulose acetate (CA), and polyethylene terephthalate (PET). In different sampling sites along the Turag River, the pollution load index (PLI) of MPs contamination was found to be in the risk level category I. The PLI values reflected the city's anthropogenic influence. The findings of the study could be used to establish a baseline for MPs pollution in Bangladesh's vast freshwater ecosystem.