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为分析工程性低温热解技术对土壤和底泥中总汞及形态汞变化的影响,采集T1区(化工污染类型)稻田土、河道底泥及T2区(矿山冶炼类型)稻田土进行处理,并对处理前后土样总汞及形态汞浓度进行测定。结果表明,低温工程性修复高浓度汞污染土壤和底泥中总汞去除率可达70%以上,T1区稻田土、底泥及T2区稻田土中有机结合态汞分别降低84.2%、71.4%、92.2%,残渣态汞分别降低58.9%、69.4%、95.2%;不同污染形式所形成的汞污染状况不同,相较于T2区,T1区有机结合态高、残渣态低;热解后土壤露天放置相比于密封存储,有机结合态增高4.1%,残渣态降低4.3%,由于受到生态环境的影响,可能存在残渣态向有机结合态转化的趋势。以潜在生态危害指数法对土壤和底泥中总汞及生物有效态汞进行生态风险评价发现,低温热解修复效果表现为稻田土优于底泥。 相似文献
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为准确预测区域水资源承载力的变化趋势和制定优化的调控方案,从"经济社会-水资源-生态环境"系统互馈机理出发,建立水资源承载力水量、水质、水域空间、水流的全要素诊断体系,识别关键驱动指标;采用支持向量机、系统动力学等多种方法,建立水资源承载力定量动态预测模型,同时制定调控目标,结合分析驱动指标的实现难易程度和代价,采用正交试验方法,优选承载力提升和减负方案。应用于黄河流域水量要素承载力的诊断、预测与调控,结果表明,南水北调西线工程等调水工程运行前各规划水平年黄河流域、上游区、中游区、下游区均处于超载或严重超载状态,运行后均处于临界超载或超载状态,选择非常规水利用、入海水量、亩均灌溉用水量、灌溉面积、万元工业增加值用水量、工业增加值等6个关键驱动指标,进行正交试验,得到了各水平年水量承载力均不超载的最优调控方案,可为黄河流域水资源管理工作提供指导。 相似文献
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According to the drought and waterlogging disaster statistics over the last 30 years (1950-1979), the annual average area suffering from drought was about 300 million mu (1 mu= 1/ 15 ha) in the whole country, among which about 100 million mu were disastrous areas where the output reduced more than 30%. and the annual lost grains totalled about 5 billion kg. The waterlogging disaster was less than drought disaster. The area suffering from waterlogging was about 100 million mu, among which 60 million mu were disastrous. Drought and waterlogging disasters affect directly the development of the national economy. So it is important to study drought and waterlogging variations, especially the drought and waterlogging variation laws of the areas where the disasters frequently occur.The historical literatures and recent observation data reveal the fact that there existed drought and waterlogging variations. For example, the occurrence frequency of the outstanding and severe drought years in north China is highe 相似文献