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%).

Heavy metal contamination of soil and sediment in estuaries warrants study because a healthy estuarine environment, including healthy soil, is important in order to achieve ecological balance and good aquaculture production. The Ba Lat estuary of the Red River is the largest estuary in northern Vietnam and is employed in various land uses. However, the heavy metal contamination of its soil has not yet been reported. The following research was conducted to clarify contamination levels, supply sources, and the effect of land use on heavy metal concentrations in the estuary. Soil samples were collected from the top soil layer of the estuary, and their arsenic (As), chromium (Cr), cadmium (Cd), copper (Cu), lead (Pb), and zinc (Zn) concentrations were analyzed, as were other soil properties. Most soils in the estuary were loam, silt loam, or sandy loam. The pH was neutral, and the cation exchange capacity ranged from 3.8 to 20 cmol·kg⁻¹. Manganese and iron concentrations averaged 811 µg·g⁻¹ and 1.79%, respectively. The magnitude of the soil heavy metal concentrations decreased in the order of Zn > Pb > Cr > Cu > As > Cd. The concentrations were higher in the riverbed and mangrove forest than in other land-use areas. Except for As, the mean heavy metal concentrations were lower than the permissible levels for agricultural soils in Vietnam. The principal component analyses suggested that soil As, Pb, Zn, Cd, and Cu were of anthropogenic origin, whereas Cr was of non-anthropogenic origin. The spatial distribution of concentration with land use indicated that mangrove forests play an important role in preventing the spread of heavy metals to other land uses and in maintaining the estuarine environment.

In saline water ponds in the tropics, a halocline may occur due to rainfall, especially in the rainy season. The critical impacts of haloclines in saline water ponds are heat insulation and the obstruction of vertical mixing. Considering the water quality in saline water ponds, the appearance of a halocline could have an impact on its variation, as the pond water quality may be impacted by both heat insulation and the obstruction of vertical mixing. Especially in saline water ponds with the purpose of aquaculture production, the appearance of a halocline may lead to dangerous risks, such as physiological stress on aquaculture products, increases in pathogenic micro-organisms, and deterioration of water quality. In the present study, the impact of the appearance of a halocline on physical water qualities was investigated by analyzing continuous on-site observation data obtained in Thailand. It was found that, after the appearance of the halocline, the heat was stored in the lower high-salinity layer, due to the heat insulation effect of the halocline. Furthermore, the halocline was also suggested to have an impact on the transportation of turbidity and to change the DO (dissolved oxygen) distribution in the vertical direction. These results are expected to provide information for assessment of the risk in saline water ponds and to contribute to a new approach for understanding deterioration problems in saline water aquaculture ponds.

Accurate weather forecasting is of paramount importance for a wide range of practical applications, drawing substantial scientific and societal interest. However, the intricacies of weather systems pose substantial challenges to accurate predictions. This research introduces a multilayer perceptron model tailored for weather forecasting in Itoshima, Kyushu, Japan. Our meticulously designed architecture demonstrates superior performance compared to existing models, surpassing benchmarks such as Long Short-Term Memory and Recurrent Neural Networks.