Istituto di Ricerca Sulle Acque, Consiglio Nazionale delle Ricerche (IRSA-CNR), Via Salaria, Km 29.300, CP10, 00015 Monterotondo (Roma), Italy.
Istituto di Ricerca Sulle Acque, Consiglio Nazionale delle Ricerche (IRSA-CNR), Via Salaria, Km 29.300, CP10, 00015 Monterotondo (Roma), Italy.
Sci Total Environ. 2014 Jun 15;484:74-83. doi: 10.1016/j.scitotenv.2014.03.019. Epub 2014 Mar 29.
Flood and drought events of higher intensity and frequency are expected to increase in arid and semi-arid regions, in which temporary rivers represent both a water resource and an aquatic ecosystem to be preserved. In this study, we explored the variation of two classes of hazardous substances (Polycyclic Aromatic Hydrocarbons and Nonylphenols) and the functioning of the microbial community in river sediments subject to hydrological fluctuations (Candelaro river basin, Italy). Overall, the concentration of pollutants (∑PAHs range 8-275ngg(-1); ∑NPs range 299-4858ngg(-1)) suggests a moderate degree of contamination. The conditions in which the sediments were tested, flow (high/low) and no flow (wet/dry/arid), were associated to significant differences in the chemical and microbial properties. The total organic carbon contribution decreased together with the stream flow reduction, while the contribution of C-PAHs and C-NPs tended to increase. NPs were relatively more concentrated in sediments under high flow, while the more hydrophobic PAHs accumulated under low and no flow conditions. Passing from high to no flow conditions, a gradual reduction of microbial processes was observed, to reach the lowest specific bacterial carbon production rates (0.06fmolCh(-1)cell(-1)), extracellular enzyme activities, and the highest doubling time (40h) in arid sediments. In conclusion, different scenarios for the mobilization of pollutants and microbial processes can be identified under contrasting hydrological conditions: (i) the mobilization of pollutants under high flow and a relatively higher probability for biodegradation; (ii) the accumulation of pollutants during low flow and lower probability for biodegradation; (iii) the drastic reduction of pollutant concentrations under dry and arid conditions, probably independently from the microbial activity (abiotic processes). Our findings let us infer that a multiple approach has to be considered for an appropriate water resource exploitation and a more realistic prevision of the impact of pollutants in temporary waters.
预计在干旱和半干旱地区，洪水和干旱事件的强度和频率将会增加，在这些地区，临时河流既是一种水资源，也是一个需要保护的水生生态系统。在这项研究中，我们探讨了两类危险物质（多环芳烃和壬基酚）的变化以及受水文波动影响的河流沉积物中微生物群落的功能（意大利坎德拉罗河流域）。总的来说，污染物浓度（∑PAHs 范围 8-275ngg(-1)；∑NPs 范围 299-4858ngg(-1)）表明存在中度污染。测试沉积物的条件，水流（高/低）和无水流（湿/干/干旱），与化学和微生物特性的显著差异有关。随着溪流流量的减少，总有机碳的贡献也随之减少，而 C-PAHs 和 C-NPs 的贡献则趋于增加。在高流量下，NPs 相对更集中在沉积物中，而疏水性更强的 PAHs 在低流量和无水流条件下积累。从高流量到无水流条件，微生物过程逐渐减少，在干旱沉积物中达到最低的特定细菌碳产生速率（0.06fmolCh(-1)细胞(-1)）、胞外酶活性和最高的倍增时间（40h）。总之，在不同的水文条件下，可以识别出污染物和微生物过程的不同迁移情景：（i）在高流量下污染物的迁移，以及相对较高的生物降解可能性；（ii）在低流量下污染物的积累，以及生物降解可能性较低；（iii）在干燥和干旱条件下污染物浓度的急剧下降，可能与微生物活性（非生物过程）无关。我们的研究结果表明，必须考虑采用多种方法来合理开发水资源，并更现实地预测污染物对临时水的影响。
