Simul Bhuyan

Rapid industrial growth and urban expansion have exacerbated the pollution of coastal beach sediments with heavy metals (HMs), particularly in developing countries such as Bangladesh, where the persistence and toxicity of these pollutants pose significant environmental and human health risks. Thus, this study investigated the contamination of HMs (Cu, Zn, Mn, Fe, Cd, Pb) to evaluate their associated risks at Kolatoli Beach, Cox’s Bazar, Bangladesh. Additionally, sediment texture analysis was performed to assess grain size distribution, which influences the mobility of these metals. The ecological risk (ER) was assessed through multiple indices, including the geo-accumulation index (Igeo), contamination factor (CF), pollution load index (PLI), ecological risk, and potential ecological risk index (PERI). Moreover, human health risk assessment (HHRA) was conducted for children and adults to determine non-carcinogenic and carcinogenic risks (CRs) through ingestion, inhalation, and dermal exposure. The sediment was predominantly sandy (93.72%), with lower clay (0%-2.51%) and silt (3.77%-6.28%) contents. The mean HM concentration in the sediment samples followed the descending order of Fe > Mn > Cu > Zn > Pb > Cd. The Igeo, CF, and PLI values indicated anthropogenic Cu and Pb accumulation in beach sediments, while Zn, Mn, and Fe remained at background levels. The PERI values ranged from 29.24 to 42.37, categorizing all samples under the ‘low ER’ classification (PERI < 150), though Pb and Cu had higher ER values. The overall hazard index (HI) values were below 1 for both age groups, indicating no significant non-carcinogenic risk (NCR). Total carcinogenic risk (TCR) values (5.99 × 10-6 for children, 3.99 × 10-6 for adults) remained within safe limits, though children posed higher CR. The statistical analyses revealed that HM contaminations were influenced by multiple factors. Overall, the study showed low to moderate HM contamination in the beach sediments, with tolerable ecological and human health risks.

Lakes are critical resources that support the ecological balance and provide essential services for human and environmental well-being. However, their quality is being increasingly threatened by both natural and anthropogenic processes. This study aimed to assess the water quality and the presence of heavy metals in 15 lakes in the Vidarbha and Marathwada regions of Maharashtra, India. To understand the extent of pollution and its sources, the physico-chemical parameters were analyzed which included pH, turbidity, total hardness, orthophosphate, residual free chlorine, chloride, fluoride, and nitrate, as well as heavy metals such as iron, lead, zinc, copper, arsenic, chromium, manganese, cadmium, and nickel. The results revealed significant pollution in several lakes, with the Lonar Lake showing a pH value of 12, exceeding the Bureau of Indian Standards’ (BIS) limit. The Lonar Lake also showed elevated levels of fluoride having a value of 2 mg/L, nitrate showing a value of 45 mg/L, and orthophosphate showing a concentration up to 2 mg/L. The Rishi Lake had higher concentrations of nickel having a value of 0.2 mg/L and manganese having a value of 0.7 mg/L, crossing permissible BIS limits. The Rishi Lake and the Salim Ali Lake exhibited higher copper levels than other lakes. Cadmium was detected in most of the lakes ranging from values of 0.1 mg/L to 0.4 mg/L, exceeding BIS limits. The highest turbidity levels were observed in Rishi Lake and Salim Ali Lake at 25 NTU. The total hardness value observed in the Kharpudi Lake was 400 mg/L, which is highest among all the lakes under study. The spatial analysis, which utilized remote sensing and GIS techniques, including Sentinel-2 multispectral imagery for land use and land cover mapping and Digital Elevation Model (DEM) for watershed delineation, provided insights into the topography and drainage patterns affecting these lakes. The findings emphasize the urgent need for targeted management strategies to mitigate pollution and protect these vital freshwater ecosystems, with broader implications for public health and ecological sustainability in regions reliant on these water resources.

Heavy metal pollution in marine ecosystems is an escalating environmental concern, largely driven by anthropogenic activities, and poses potential threats to ecological health and human well-being. This study embarked on a comprehensive investigation into the concentrations of heavy metals in sediment samples and evaluated their potential ecological and health risks with a focus on Eastern St. Martin’s Island (SMI), Bangladesh. Sediment samples were meticulously collected from 12 distinct sites around the island, and the concentrations of heavy metals, including Mn, Fe, Ni, Zn, Cr, Pb, and Cu, were quantified utilizing atomic absorption spectrometry (AAS). The results revealed that the average concentrations of the metals, in descending order, were Mn (269.5 ± 33.0 mg/kg), Fe (143.8 ± 21.7 mg/kg), Ni (29.6 ± 44.0 mg/kg), Zn (27.2 ± 4.34 mg/kg), Cr (8.09 ± 1.67 mg/kg), Pb (5.88 ± 0.45 mg/kg), and Cu (3.76 ± 0.60 mg/kg). Intriguingly, the concentrations of all the measured metals were found to be within permissible limits and comparatively lower than those documented in various national and international contexts. The ecological risk assessment, based on multiple sediment quality indices such as the geoaccumulation index, contamination factor, and pollution load index, indicated a moderate risk to the aquatic ecosystem but no significant adverse impact on sediment quality. Additionally, the human health risk assessment, encompassing non-carcinogenic hazard indices for different age groups, was considerably below the threshold, signifying no immediate health risk. The total carcinogenic risk was also found to be below acceptable levels. These findings underscore the current state of heavy metal pollution in Eastern St. Martin’s Island, providing valuable insights for environmental monitoring and management. While the immediate risks were not alarming, the study highlights the imperative need for sustained monitoring and the implementation of rigorous regulations to curb heavy metal pollution in order to safeguard both ecological and human health. This warrants the development of policies that are both adaptive and preemptive to ensure the sustainable utilization and conservation of marine resources.