Chongming Island is located in the lower Yangtze Estuary in China. Due to the Leachate from a refuse landfill and the hydrodynamics of the Yangtze Estuary, the groundwater environment is particularly complicated on Chongming Island. Field observations were carried out around the landfill disposal site. The groundwater table, temperature, pH, salinity, and dissolved oxygen were measured in the field by portable equipment, and 192 water samples were collected at eight groundwater sites and one surface water site. Through laboratory analysis we found the highest measured concentration of Cr to be 54.07 μg/L, and the measured concentration of Zn was in the range of 8 μg/L to more than 200 μg/L, which were both higher than their background values. Strong correlations were found between the heavy metal (Cr, Ni, Cu) concentrations and physico-chemical characteristics (salinity and pH), which indicated that both the landfill and the tides played an important role in the distribution of heavy metal concentrations. Both the HPI and PoS Indices were greater than their critical values near the disposal site, indicating groundwater pollution by heavy metals. We show that Cr and Ni are the major heavy metals causing groundwater contamination in the study region.

This article considers the impact of rainfall floods of the Amur river on the distribution of suspended sediments and the content of heavy metals in the watercourse. It presents measurement data of these parameters for equal flood rise and fall flows. The authors found out that factors like a high proportion of watercourse width to its depth, the presence of large tributaries, and the branching of the river course have the strongest impact on the heterogeneity of the distribution of terrigenous and chemical substances across the length and width of the river. They also identified the key impacts of large floods that transform the river course and have negative effects on the reliability and conditions of waterworks within urban territories.

Despite its positive impacts on traffic convenience and resource delivery, metro construction tilts the balance of groundwater resources and destabilizes the groundwater environment. This paper explores the impacts of shield tunnel construction on groundwater environment from the design and construction to an operating metro project, and verifies these impacts through an analysis on the tunnel project in Jinan Metro Line R3. The research shows that the grouting in shield tunneling has a local influence on the groundwater quality and pH, which attenuates with the increase of distance to the tunnel axis; the scope of influence is constrained by the formation lithology. Then, the backpropagation (BP) neural network was adopted to predict the ejection volume of groundwater, and the main influencing factors of water environment were disclosed by analytical hierarchy process (AHP). Finally, the author discussed the key techniques and prevention systems for prevention of the impacts of shield tunnel construction on water environment.