Remote Sensing and GIS Support to Identify Potential Areas for Wetland Restoration from Cropland: A Case Study in the West Songnen Plain, Northeast China

Groundwater chemistry and health risks associated with nitrate intake in Hailun, northeast China

In order to quantify the hydrochemical characteristics of groundwater in Hailun, analyze the hydrochemical process, and evaluate its health risks associated with nitrate intake, 77 shallow groundwater samples were collected and analyzed. The results show that groundwater in the study area is weakly acidic and groundwater chemical type was dominated by HCO₃-Ca, HCO₃•Cl-Ca, HCO₃-Ca•Na and HCO₃•Cl-Ca•Na. Rock weathering and dissolution, ion exchange, and human activities are the main reasons affecting the chemical composition of shallow groundwater in Hailun. The weathering and dissolution process of silicate under weakly alkaline conditions is the source of Na. The dissolution of calcite, dolomite, and gypsum are the main form of water-rock interaction. Results of health risk assessment show that the HQ value for adult males, adult females, children, and infants were in range of 0-1.52, 0-1.75, 0-3.58 and 0-6.08, respectively, and with a mean value of 0.19, 0.22, 0.44, 0.75, respectively. The harm of NO₃ pollution is in the order of infant > child > adult female > adult male. The results of this study made local governments pay attention to drinking water safety issues for local residents.

Inland water bodies in China: Features discovered in the long-term satellite data

Water bodies (WBs), such as lakes, ponds, and impoundments, provide essential ecosystem services for human society, yet their characteristics and changes over large areas remain elusive. Here we used unprecedented data layers derived from all Landsat images available between 1984 and 2015 to understand the overall characteristics and changes of WBs between 2 epochs (i.e., 1984 to 1999 and 2000 to 2015) in China. Results show that the abundance estimate of WBs greater than 1 km² and the total WB surface area were 0.3 to 1.5 times and 0.2 to 0.5 times more than the previous estimates, respectively. The size-abundance and shoreline-area relationships of WBs in China conformed to the classic power scaling law, in contradiction to most previous studies. WB changes with various occurrence probabilities show widespread coexistence of disappearance of existent and emergence of new WBs across China driven primarily by human activities and climate change. Our results highlight the importance of using appropriate long-term satellite data to reveal the true properties and dynamics of WBs over large areas, which is essential for developing scaling theories and understanding the relative impacts of human activities and climate change on water resources in the world.