Department of Civil & Resource Engineering Dalhousie University Office D-514, 1360 Barrington Street Halifax, Nova Scotia, Canada B3H 4R2.
Halifax Water, 450 Cowie Hill Road, Halifax, Nova Scotia, Canada B3P 2V3.
Environ Sci Technol. 2017 Feb 7;51(3):1414-1422. doi: 10.1021/acs.est.6b04889. Epub 2017 Jan 17.
This study examined sulfate deposition in Nova Scotia from 1999 to 2015, and its association with increased pH and organic matter in two protected surface water supplies (Pockwock Lake and Lake Major) located in Halifax, Nova Scotia. The study also examined the effect of lake water chemistry on drinking water treatment processes. Sulfate deposition in the region decreased by 68%, whereas pH increased by 0.1-0.4 units over the 16-year period. Average monthly color concentrations in Pockwock Lake and Lake Major increased by 1.7 and 3.8×, respectively. Accordingly, the coagulant demand increased by 1.5 and 3.8× for the water treatment plants supplied by Pockwock Lake and Lake Major. Not only was this coagulant increase costly for the utility, it also resulted in compromised filter performance, particularly for the direct-biofiltration plant supplied by Pockwock Lake that was found to already be operating at the upper limit of the recommended direct filtration thresholds for color, total organic carbon and coagulant dose. Additionally, in 2012-2013 geosmin occurred in Pockwock Lake, which could have been attributed to reduced sulfate deposition as increases in pH favor more diverse cyanobacteria populations. Overall, this study demonstrated the impact that ambient air quality can have on drinking water supplies.
本研究考察了 1999 年至 2015 年期间新斯科舍省硫酸盐的沉积情况，以及硫酸盐沉积与哈利法克斯两个地表水供水系统（波克沃克湖和梅杰湖）中 pH 值和有机物增加的关系。该研究还考察了湖水化学对饮用水处理工艺的影响。在 16 年期间，该地区的硫酸盐沉积减少了 68%，而 pH 值增加了 0.1-0.4 个单位。波克沃克湖和梅杰湖的平均每月色度浓度分别增加了 1.7 倍和 3.8 倍。相应地，为波克沃克湖和梅杰湖供水的水处理厂的混凝剂需求分别增加了 1.5 倍和 3.8 倍。这种混凝剂的增加不仅对公共事业造成了成本上的负担，而且还导致了过滤性能的下降，特别是对直接生物过滤厂的影响更为明显，该水厂已经处于推荐的直接过滤阈值的上限，其对色度、总有机碳和混凝剂剂量的要求都很严格。此外，2012 年至 2013 年，波克沃克湖出现了土臭素，这可能归因于硫酸盐沉积的减少，因为 pH 值的增加有利于更多样化的蓝藻种群的生长。总的来说，本研究表明了大气环境质量对饮用水供应的影响。
