Galella Joseph G, Kaushal Sujay S, Wood Kelsey L, Reimer Jenna E, Mayer Paul M
Department of Geology & Earth System Science Interdisciplinary Center University of Maryland College Park, MD 20140.
US Environmental Protection Agency Office of Research and Development Center for Public Health and Environmental Assessment Corvallis, OR 97333.
Environ Res Lett. 2021 Mar 1;16(3):035017-35017. doi: 10.1088/1748-9326/abe48f.
Increasing trends in base cations, pH, and salinity of freshwaters have been documented in U.S. streams over 50 years. These patterns, collectively known as Freshwater Salinization Syndrome (FSS), are driven by multiple processes, including applications of road salt and human-accelerated weathering of impervious surfaces, reductions in acid rain, and other anthropogenic legacies of change. FSS mobilizes chemical cocktails of distinct elemental mixtures ion exchange, and other biogeochemical processes. We analyzed impacts of FSS on streamwater chemistry across five urban watersheds in the Baltimore-Washington, USA metropolitan region. Through combined grab-sampling and high-frequency monitoring by USGS sensors, regression relationships were developed among specific conductance and major ion and trace metal concentrations. These linear relationships were statistically significant in most of the urban streams (, R = 0.62 and 0.43 for Mn and Cu, respectively), and showed that specific conductance could be used as a proxy to predict concentrations of major ions and trace metals. Major ions and trace metals analyzed linear regression and principal component analysis (PCA) showed co-mobilization (, correlations among combinations of specific conductance, Mn, Cu, Sr, and all base cations during certain times of year and hydrologic conditions). Co-mobilization of metals and base cations was strongest during peak snow events but could continue over 24 hours after specific conductance peaked, suggesting ongoing cation exchange in soils and stream sediments. Mn and Cu concentrations predicted from specific conductance as a proxy indicated acceptable goodness of fit for predicted observed values (Nash-Sutcliffe Efficiency > 0.28). Metals concentrations remained elevated for days after specific conductance decreased following snowstorms, suggesting lag times and continued mobilization after road salt use. High-frequency sensor monitoring and proxies associated with FSS may help better predict contaminant pulses and contaminant exceedances in response to salinization and impacts on aquatic life, infrastructure, and drinking water.
在美国，50多年来的溪流记录显示，淡水的碱金属阳离子、pH值和盐度呈上升趋势。这些模式统称为淡水盐碱化综合征（FSS），是由多种过程驱动的，包括道路盐分的使用、不透水表面的人为加速风化、酸雨减少以及其他人为造成的变化遗留问题。FSS通过离子交换和其他生物地球化学过程，使不同元素混合物的化学混合物得以流动。我们分析了FSS对美国巴尔的摩-华盛顿大都市地区五个城市流域溪流水化学的影响。通过美国地质调查局（USGS）传感器的联合抓取采样和高频监测，得出了电导率与主要离子和痕量金属浓度之间的回归关系。这些线性关系在大多数城市溪流中具有统计学意义（锰和铜的R值分别为0.62和0.43），表明电导率可以用作预测主要离子和痕量金属浓度的指标。通过线性回归和主成分分析（PCA）分析主要离子和痕量金属，结果显示它们共同流动（在一年中的某些时间和水文条件下，电导率、锰、铜、锶和所有碱金属阳离子的组合之间存在相关性）。金属和碱金属阳离子的共同流动在降雪峰值期间最强，但在电导率达到峰值后可能持续24小时以上，这表明土壤和溪流沉积物中存在持续的阳离子交换。以电导率为指标预测的锰和铜浓度表明，预测值与观测值的拟合优度可以接受（纳什-萨特克利夫效率>0.28）。暴风雪后电导率下降数天，金属浓度仍居高不下，这表明道路盐分使用后存在滞后时间和持续的流动。与FSS相关的高频传感器监测和指标可能有助于更好地预测盐渍化对水生生物、基础设施和饮用水造成的污染脉冲和污染物超标情况。
