Abstract：
The EU Water Framework Directive requires the monitoring and evaluation of surface water sediment quality based on the assessment of risk posed by contamination on the biotic receptors. Floodplain sediments are important receptors of potentially toxic element (PTE) contamination from the upstream catchment areas, and floodplains host climate-sensitive riverine ecosystems and fertile agricultural areas at the same time. This study investigates the effect of PTE contamination on microbial communities in floodplain sediments and soils using the fast, inexpensive and reliable fluorescein diacetate (FDA) method in order to estimate its applicability for sediment quality monitoring and preliminary toxicity-based risk assessment. Sediment and soil samples were collected from the actively flooded alluvial plain and the river terrace areas along a 130-km stretch of the large Drava River floodplain known to be widely contaminated by historical mining, smelting and the associated industry in the upstream Alpine region. Results of detailed data analysis show that the total microbial activity represented by the measured FDA values is related to PTE (As, Cu, Zn, Cd, Pb) concentrations, but this relationship shows significant heterogeneity and depends on the spatial location and on the soil properties such as organic matter content, dissolved salt and nutrient content, and it is specific to the toxic elements. Results show that some microbe species appear to be able to adapt to the elevated PTE concentrations in toxic soil micro-environments, over time. Despite the observed heterogeneity of microbial activity, the results revealed a breakpoint in the FDA dataset around the FDA = 3 FC (fluorescein concentration) value suggesting that microbial activity is controlled by thresholds.
摘要：
欧盟水框架指令要求根据对生物受体污染造成的风险的评估，对地表水沉积物质量进行监测和评估。洪泛区沉积物是上游集水区潜在有毒元素（PTE）污染的重要受体，洪泛区同时拥有对气候敏感的河流生态系统和肥沃的农业区。这项研究调查了PTE污染对洪泛区沉积物和土壤中微生物群落的影响，廉价且可靠的荧光素二乙酸酯（FDA）方法，以评估其在沉积物质量监测和基于毒性的初步风险评估中的适用性。沉积物和土壤样本是从活跃淹没的冲积平原和沿着大型德拉瓦河洪泛区130公里长的河流梯田地区收集的，这些洪积平原被历史采矿广泛污染，上游高山地区的冶炼及相关产业。详细数据分析的结果表明，由FDA测量值表示的总微生物活性与PTE（As，Cu,Zn,Cd,Pb)浓度,但这种关系表现出显著的异质性，取决于空间位置和土壤特性，如有机质含量，溶解盐和营养成分，它是特定于有毒元素的。结果表明，一些微生物物种似乎能够适应有毒土壤微环境中升高的PTE浓度，随着时间的推移。尽管观察到微生物活性的异质性，结果显示,FDA数据集中在FDA=3FC(荧光素浓度)值附近有一个断点,提示微生物活性受阈值控制.
