Heavy metal (Cr, Cu, Zn, As, Cd, and Pb) contamination in irrigation water, soil, and vegetables was investigated in farmland adjacent to a multi-industry zone in Bangladesh in dry and wet seasons. In the zone, many factories release wastewater into nearby irrigation canals, and vegetables cultivated with this water could be a major food chain route for human exposure. In the irrigation water and vegetables, heavy metal concentrations exceeded permissible levels in the two seasons, but this was not the case in soil. Zn had the highest concentration, and Cd had the lowest concentration in irrigation water, soil, and vegetables. All heavy metal concentrations were found to be lower in the wet than in the dry season, which is due to the dilution of water by rainfall, lower absorption of heavy metals from the diluted irrigation water, and heavy metal absorption from low concentrated irrigation water and/or soil. The cluster analysis data of irrigation water, soil, and vegetables revealed that the heavy metals in vegetables were considered to be absorbed from irrigation water in the wet season and from soil in the dry season. In the dry season, the high heavy metal concentrations in vegetables might be caused by a high bioconcentration factor (mostly > 20%).

Assessing and modeling the changes in land use and land cover (LULC) patterns and associated ecosystem service values (ESV) has become an important global agenda for formulating sustainable land management policies. Taking the coastal region of Bangladesh (CRB) as a case study, we utilized remote sensing and GIS techniques to analyze Landsat data of 1999 and 2019 to estimate the effect of LULC changes on the ESVs. The LULC classification, ESV quantification, and spatial variations were performed by semi-automated classification, per-unit value transfer, and spatial autocorrelation techniques, respectively. First, between 1999 and 2019, LULC altered dramatically (agricultural land and coastal wetlands decreased, while all other LULC types increased). Second, the total ESV decreased by 1.87%, which was mostly attributed to a 70% growth in both rural settlement and aquaculture/saltpan, and a 30% decline in both agricultural land and wetlands. Third, significant spatial correlation and moderately high spatial clustering were observed, which consisted mostly of mangrove forests, waterbodies, and wetland zones. Both high-high and low-low values increased, but spatial outliers remained unchanged. Conserving agricultural land should be prioritized in future land use plans of CRB to meet the ever-increasing food demands, control natural land conversion, and make land use sustainable.

The arsenic (As) concentrations of irrigation water, soils and vegetables were investigated in an agricultural section of Gazipur industrial area in Bangladesh, where industrial wastewater is mixed with irrigation water. The results showed that the mean As concentration of the irrigation water (0.16-0.62 mg L-1) exceeded the permissible limit for agricultural purposes recommended by the Food and Agriculture Organization (0.10 mg L-1). The mean As concentration of soils (6.48-9.75 mg kg-1) did not exceed the tolerable limit for agricultural soils recommended by the FAO (20.0 mg kg-1). While, the As concentration of the respective vegetables in average varied from 0.63 to 1.07 mg kg-1 dry weight, and the highest As concentration in average was observed in taro root (1.26-2.31 mg kg-1), followed by helencha leaf (1.85-2.02 mg kg-1). The average As concentration of root vegetables (1.84 mg kg-1) exceeded the permissible limit of 1.0 mg kg-1 suggested by the Food and Agriculture Organization, while that of leafy (0.77 mg kg-1) and fruit vegetables (0.14 mg kg-1) did not exceed the limit. Soils irrigated with As containing water that holds much amount of As showed a positive correlation with the vegetable As concentration. A decrease in the As concentration from soil to vegetable was found in root, leafy and fruit vegetables. However, the vegetables were not safe for human consumption. Some countermeasures are, therefore, necessary to reduce the vegetable As concentration.INTERNATIONAL JOURNAL OF ENVIRONMENT Volume-6, Issue-1, Dec-Feb 2016/17, page: 76-86