Spatial distribution and transport of heavy metals in soil, ponded-surface water and grass in a pb-contaminated watershed as related to land-use practices

The aim of this study was to investigate the spatial distribution of heavy metal in soil and evaluate the dissolution of metal from soil to ponded-surface water, leaching through soil profiles and metal uptake in grass as related to different land-use practices. The data provided a scientific basis for best-management practices for land use in Khli Ti watershed. The watershed has a Pb-contamination problem from the previous operation of a Pb-ore concentrator and abandoned Zn–Pb mine. Sampling sites were selected from a land-use map, with land-use types falling into the following four categories: forest, agricultural land, residential area and road. Soil, ponded-surface water, grass samples and soil profiles were collected. The study related soil characteristics from different land-use practices and locations with observed metal concentrations in ponded-surface water and soil. High enrichment factors of Pb and As in soil were found. Partitioning coefficient, K_d values were in the order: Cr > Pb > Ni > Cu > Cd > Zn. Soil disturbance from land-use activities including tillage and traffic increased leaching of trace metal from soils. Pb in soil was significantly taken up by grass even though the Transfer Factor, TF values were rather low. Agricultural activities in the watershed must be limited. Moreover, land encroachments in the upper and middle part of the watershed which have high potential of Pb must be strictly controlled in order to reduce the Pb contamination from non-point sources.     

An implementation plan for using biological indicators to improve assessment of water quality in Thailand

The present study showed a possibility to use phenotypic and proteomic responses in rice plants as an in vivo biomarker to detect higher concentrations of ambient ozone (O₃). The investigation was done on two cultivars of Indian rice using open top chambers ventilated with charcoal filtered air, ambient air, ambient air with 10 ppb O₃ exposure and ambient air with 20 ppb O₃ exposure at a rural site of Varanasi, India. Results showed that the magnitude of O₃ induced specific type of foliar injury directly depends on the duration and concentration of O₃ exposure. Even the internal protein profile of injured and normal leaf demonstrated a differential expression, which directly indicates towards the molecular basis of plant’s response against O₃.