Eawag, Swiss Federal Institute of Aquatic Science and Technology (Eawag), 8600, Dübendorf, Switzerland.
, Uster, Switzerland.
Environ Sci Pollut Res Int. 2018 Jun;25(17):16788-16809. doi: 10.1007/s11356-018-1679-x. Epub 2018 Apr 3.
Long-term changes of 14 water constituents measured in continuously and water discharge proportionally collected samples of four Swiss rivers over a period of 39 years are analyzed using several statistical techniques. Possible drivers and causes for the identified trends and shifts are explained by consideration of catchment characteristics and anthropogenic activities. Water temperatures increased by 0.8-1.3 °C, whereas water discharges remained largely unchanged. Concentrations of alkalinity, total hardness, Ca, and Mg regulated by dominant carbonate lithologies in catchments increased by up to 10%. We attribute this change to an increase in the partial pressure of CO in the subsurface, provoked by increasing temperatures. Re-oligotrophication processes in lakes also influence the behavior of alkalinity and silicic acid. In contrast to concentrations, most loads did not change significantly, due to their large variances. Therefore, no changes in overall weathering rates of carbonate rocks can be detected. The outgassing of CO in rivers from the place of carbonate dissolution to measurement stations amounts up to 6% (mean) of CO sequestered (mean 1.1 mol m a) by the weathering of rock minerals. Changes in alkalinity/Ca/Mg ratios indicate an increase in calcite precipitation over time. Total nitrogen concentrations and loads peaked at the end of the 1980s and then decreased up to 50%, while NO concentrations showed almost no changes. This dynamic matches the changes in the agricultural N balance. Concentrations and loads of Na and Cl increased up to 60% due to an increase in the various uses of rock salt.
对四条瑞士河流连续采集和按流量比例采集的样本中的 14 种水质成分进行了长达 39 年的监测，利用多种统计技术对其长期变化进行了分析。通过考虑流域特征和人为活动，对确定的趋势和变化的可能驱动因素和原因进行了解释。水温升高了 0.8-1.3°C，而水流基本保持不变。受流域主要碳酸盐岩控制的碱度、总硬度、Ca 和 Mg 浓度增加了高达 10%。我们将这种变化归因于地下 CO2分压的增加，这是由温度升高引起的。湖泊的再贫营养化过程也影响碱度和硅酸的行为。与浓度相比，由于其较大的方差，大多数负荷没有明显变化。因此，无法检测到碳酸盐岩石整体风化速率的变化。从碳酸盐溶解点到测量站的河流 CO2逸出量占岩石矿物风化所固定的 CO2（平均 1.1 mol m a）的 6%（平均值）。碱度/Ca/Mg 比值的变化表明，随着时间的推移，方解石沉淀增加。总氮浓度和负荷在 20 世纪 80 年代末达到峰值，然后下降了 50%，而 NO 浓度几乎没有变化。这种动态与农业氮平衡的变化相匹配。由于各种盐岩用途的增加，Na 和 Cl 的浓度和负荷增加了高达 60%。
