Geology and sediment geochemistry of a landfill leachate contaminated aquifer (Grindsted, Denmark)

A landfill leachate affected aquifer was investigated with respect to the geology and sediment geochemistry (solid organic carbon, cation exchange capacity, oxidation capacity, reduced iron and sulfur species) involving 185 sediment samples taken along a 305-m-long and 10–12-m-deep transect downgradient from the landfill. The geology showed two distinct sand layers (upper Quaternary, Weichselian and a lower Tertiary, Miocene) sandwiching thin layers of silt/clay deposits, peat and brown coal. The organic carbon content (TOC) and the cation exchange capacity (CEC) of the sandy sediments were low (TOC, 100–300 μg C (g DW)⁻¹ ; CEC, 0.1–0.5 meq per 100 g DW) and correlated fairly well with the geology. Processes in the contaminant plume caused depletion of oxidation capacity and precipitation of reduced iron and sulfur species. However, some of these parameters were also affected by the geology, e.g. the oxidation capacity (OXC) was significantly higher in the Quaternary layer (OXC, 14–35 μeq g DW⁻¹) than in the Tertiary sand layer (OXC, <5 μeq g DW⁻¹). The intermediate layers (silt/clay and brown coal) have significantly higher values of most of the parameters investigated. This work demonstrates the need for a small scale geological model and a detailed mapping of the geochemistry of the sediments in order to distinguish impacts caused by the contaminant plumes from natural variations in the aquifer geochemistry.     

地质环境与城市可持续发展

城市建设要处理好人与地质环境的关系,充分考虑地质环境的容量和质量,正确认识地质作用对地质环境的干扰。我国城市地质环境脆弱,地质灾害严重,不合理开发利用地下水诱发了一些环境地质问题,矿山城市地质环境形势严峻。以上问题威胁着城市可持续发展,必须引起高度重视。     

广州城市环境地质问题

对广州市生态环境和地质环境的分析说明,诱发地质灾害主要是人为因素,有必要提高市民的地质灾害防范意识。