Distribution, Concentration, and Ecological Risk Assessment of Trace Metals in Surface Sediment of a Tropical Bangladeshi Urban River

Spatial distribution of heavy metal abundance at distance gradients of roadside agricultural soil from the busiest highway in Bangladesh: A multi-index integration approach

Bangladesh is currently experiencing significant infrastructural development in road networking system through the construction or reconstruction of multiple roads and highways. Consequently, there is a rise in traffic intensity on roads and highways, along with a significant contamination of adjacent agricultural soils with heavy metals. The purpose of this study was to evaluate the ecological risk, health risk and the abundance of seven heavy metals (Cu, Mn, Pb, Cd, Cr, As, and Ni) in three distance gradients (0, 300, and 500 m) of agricultural soil along the Dhaka-Chattogram highway. The concentration of heavy metals was measured with an Atomic Absorption Spectrophotometer (AAS) on a total of 36 soil samples that were taken from 12 different sampling sites. Based on the findings, Cd had a high contamination factor for all distance gradients, whereas Cr had a moderate contamination factor in 67% of the study areas. According to the Pollution Load Index (PLI), Cd, Cr, and Pb were the predominant pollutants. Principal component analysis (PCA) result shows these metals mainly came from anthropogenic sources. The considerable positive correlations between Cu-Pb, Cu-Cd, Pb-Cd, and Cr-Ni all pointed to shared anthropogenic origins. As per Potential Ecological Risk Assessment (PERI) analysis, Pb, Cd, Cr, and Ni each contribute significantly and pose a moderate threat. The Target Hazard Quotient (THQ) values for all pathways of exposure to Pb and Cr in soils were more than 1, which would pose a significant risk to human health in the following order: THQadult female > THQadult male > THQchildren. This study will help to evaluate the human health risk and develop a better understanding of the heavy metal abundance scenario in the agricultural fields adjacent to this highway.

Assessment of Heavy Metal Contamination and Health Risk Associated with Cultivated Vegetables along Dhaka-Mymensingh Highway, Bangladesh

The purpose of this research work is to evaluate the degree of eight heavy metals (Fe, Mn, Cu, Zn, Cd, Pb, Cr, and Ni) contamination and health risks of three regularly consumed vegetables (papaya, bottle gourd, and esculent) near one of Bangladesh's busiest roadways, the Dhaka-Mymensingh highway. The heavy metal concentrations in 45 vegetable samples were analyzed using an atomic absorption spectrometer (AAS). These samples were collected from five different sampling sites based on various land use patterns adjacent to the highway. The average concentrations (mg/kg) of Cu, Fe, Mn, Zn, Cr, and Ni were found to be 9.86, 246.8, 16.9, 28.0, 9.02, and 2.02, respectively, for papaya; 14.9, 281.2, 387.6, 49.0, 10.1, and 2.92, respectively, for bottle gourd; and 17.6, 183.4, 107.2, 80.7, 7.98, and 2.34, respectively, for esculent. The mean concentrations of Cr, Zn, and Mn in papaya, bottle gourd, and esculent were higher than the acceptable limit. Correlation analysis revealed a significant positive correlation between Fe-Cu, Zn-Fe, Cu-Fe, and Fe-Zn in papaya; Cu-Zn, Fe-Cr, Zn-Ni, and Cr-Fe in bottle gourd; and Mn-Cr, Mn-Ni, Mn-Fe, and Cr-Ni in esculent, thereby indicating their common anthropogenic sources like agricultural activities, waste from the commercial area, filling station, and vehicular emissions. Health risk assessment through target hazard quotient (THQ) revealed the highest THQ of 9.52 for Cr in bottle gourd, which poses a high non-carcinogenic health risk to the localities upon the intake of these contaminated vegetables. Target cancer risk (TCR) was found to be highest for Cr in papaya (0.013) and bottle gourd (0.014). TCR trends were found for Cr in the following order: bottle gourd > esculent > papaya. This study contributed the greatest concern for both carcinogenic and non-carcinogenic health impacts through ingesting contaminated vegetables.

Pollution trends and ecological risks of heavy metal(loid)s in coastal zones of Bangladesh: A chemometric review

Heavy metal(loid)s inputs contribute to human and environmental stresses in the coastal zones of Bangladesh. Several studies have been conducted on metal(loid)s pollution in sediment, soil, and water in the coastal zones. However, they are sporadic, and no attempt has been made in coastal zones from the standpoint of chemometric review. The current work aims to provide a chemometric assessment of the pollution trend of metal(loid)s, namely arsenic (As), chromium (Cr), cadmium (Cd), lead (Pb), copper (Cu), zinc (Zn), and nickel (Ni) in sediments, soils, and water across the coastal zones from 2015 to 2022. The findings showed that 45.7, 15.2, and 39.1 % of studies on heavy metal(loid)s were concentrated in the eastern, central, and western zones of coastal Bangladesh. The obtained data were further modeled using chemometric approaches, such as the contamination factor, pollution load index, geoaccumulation index, degree of contamination, Nemerow's pollution index, and ecological risk index. The results revealed that metal(loid)s, primarily Cd, have severely polluted the sediments (contamination factor, CF = 5.20) and soils (CF = 9.35) of coastal regions. Water was moderately polluted (Nemerow's pollution index, P_N=5.22 ± 6.26) in the coastal area. The eastern zone was the most polluted compared to other zones, except for a few observations in the central zone. The overall ecological risks posed by metal(loid)s highlighted the significant ecological risk in sediments (ecological risk index, RI = 123.50) and soils (RI = 238.93) along the eastern coast. The coastal zone may have higher pollution levels due to the proximity of industrial effluent, residential sewage discharge, agricultural activities, sea transport, metallurgical industries, shipbreaking and recycling operations, and seaport activities, which are the major sources of metal(loid)s. This study will provide useful information to the relevant authorities and serve as the foundation for future management and policy decisions to reduce metal(loid) pollution in the coastal zones of southern Bangladesh.