Sterling Hydrology Research Group, Department of Earth Sciences , Dalhousie University , Halifax B3H 4J1 , Canada.
Environ Sci Technol. 2020 Jan 21;54(2):807-817. doi: 10.1021/acs.est.9b04872. Epub 2020 Jan 6.
Despite reductions in acidic deposition, high freshwater Al concentrations continue to threaten acidified ecosystems across the northern hemisphere. Seasonally elevated Al concentrations may pose a particular threat to freshwater organisms. Despite this threat, there is a lack of understanding about the timing and drivers of seasonal Al fluctuations. Here, we address this knowledge gap by identifying seasonal patterns of Al and their drivers in 16 rivers across Nova Scotia, Canada. We identify five distinct Al regimes with different timing of seasonally elevated Al concentrations. Regimes are distinguished by correlation strength and direction between Al and base cations, total organic carbon, turbidity, and discharge. Most notably, regimes are distinguished by a gradient of Al-base cation decoupling as Ca and Mg concentration approaches 1.4 mg L and 0.6 mg L, respectively. Seasonally elevated Al concentrations exceeded the 0.1-0.2 mg L World Health Organization drinking water guidelines in all regimes, and inorganic monomeric Al is projected to exceed the 15 μg L threshold for aquatic health in most rivers. This research highlights the complexity of seasonal Al dynamics and the importance of understanding seasonal variation of Al to quantify the impact of Al on human health, water treatment, and aquatic organisms.
尽管酸性沉降物有所减少，但高浓度的淡水铝仍继续威胁着整个北半球的酸化生态系统。季节性升高的铝浓度可能对淡水生物构成特别威胁。尽管存在这种威胁，但人们对季节性铝波动的时间和驱动因素仍缺乏了解。在这里，我们通过确定加拿大新斯科舍省 16 条河流中铝的季节性模式及其驱动因素来填补这一知识空白。我们确定了五个不同的铝区，其季节性升高的铝浓度具有不同的时间模式。这些区是通过铝与基础阳离子、总有机碳、浊度和流量之间的相关性强度和方向来区分的。最值得注意的是，区之间的区别在于铝-基础阳离子解耦程度的梯度，当 Ca 和 Mg 浓度分别接近 1.4 mg/L 和 0.6 mg/L 时。所有区的季节性升高的铝浓度均超过了世界卫生组织 0.1-0.2mg/L 的饮用水指南，而且大多数河流中的无机单体铝预计将超过水生健康的 15μg/L 阈值。这项研究强调了季节性铝动态的复杂性，以及理解铝季节性变化对量化铝对人类健康、水处理和水生生物的影响的重要性。
