University of Trento, Department of Civil, Environmental and Mechanical Engineering, Via Mesiano 77, 38123 Trento, Italy.
UFZ Helmholtz Centre for Environmental Research, Department Catchment Hydrology, Theodor-Lieser-Str. 4, 06120 Halle (Saale), Germany.
Sci Total Environ. 2018 Jan 15;612:49-62. doi: 10.1016/j.scitotenv.2017.08.172. Epub 2017 Sep 1.
This study analyses how indicators of water quality (thirteen physico-chemical variables) and drivers of change (i.e., monthly aggregated air temperature and streamflow, population density, and percentage of agricultural land use) coevolve in three large European river basins (i.e., Adige, Ebro, Sava) with different climatic, soil and water use conditions. Spearman rank correlation, Principal Component Analysis, and Mann-Kendall trend tests were applied to long-term time series of water quality data during the period 1990-2015 in order to investigate the relationships between water quality parameters and the main factors controlling them. Results show that air temperature, considered as a proxy of climatic change, has a significant impact, in particular in the Adige and Ebro: positive trends of water temperature and negative of dissolved oxygen are correlated with upward trends of air temperatures. The aquatic ecosystems of these rivers are, therefore, experiencing a reduction in oxygen, which may exacerbate in the future given the projected further increase in temperature. Furthermore, monthly streamflow has been shown to reduce in the Ebro, thereby reducing the beneficial effect of dilution, which appears evident from the observed upward patterns of chloride concentrations and electrical conductivity. Upward trends of chloride and biological oxygen demand in the Adige and Sava, and of phosphate in the Adige appears to be related to increasing human population density, whereas phosphates in the Sava and biological oxygen demand in the Ebro are highly correlated with agricultural land use, considered as a proxy of the impact of agricultural practises. The present study shows the complex relationships between drivers and observed changes in water quality parameters. Such analysis can represent, complementary to a deep knowledge of the investigated systems, a reliable tool for decision makers in river basin planning by providing an overview of the potential impacts on the aquatic ecosystem of the three basins.
本研究分析了水质指标（十三项理化变量）和变化驱动因素（即逐月综合的空气温度和径流量、人口密度以及农业用地比例）在三个具有不同气候、土壤和用水条件的欧洲大型流域（阿迪杰河、埃布罗河、萨瓦河）中的协同演变。为了研究水质参数与控制它们的主要因素之间的关系，本研究应用 Spearman 秩相关分析、主成分分析和 Mann-Kendall 趋势检验对 1990 年至 2015 年期间的水质数据进行了长期时间序列分析。结果表明，空气温度作为气候变化的代理，具有显著的影响，特别是在阿迪杰河和埃布罗河：水温呈上升趋势，溶解氧呈下降趋势，与空气温度的上升趋势相关。因此，这些河流的水生生态系统正在经历氧气减少的问题，而考虑到未来气温的进一步升高，这一问题可能会更加严重。此外，埃布罗河的月径流量呈减少趋势，从而降低了稀释的有益效果，这从氯浓度和电导率的观测上升模式中可以明显看出。阿迪杰河和萨瓦河的氯化物和生物需氧量呈上升趋势，阿迪杰河的磷酸盐呈上升趋势，这似乎与人口密度的增加有关，而萨瓦河的磷酸盐和埃布罗河的生物需氧量与农业用地比例高度相关，后者被视为农业实践影响的代理。本研究表明了驱动因素与水质参数观测变化之间的复杂关系。这种分析可以作为对被研究系统的深入了解的补充，为决策者在流域规划中提供一个概述，说明三个流域的水生生态系统可能受到的潜在影响，从而成为一个可靠的工具。
