Department of Civil, Environmental and Architectural Engineering, University of Colorado, Boulder, CO 80309, USA.
City of Fort Collins Utilities, Fort Collins, CO 80521, USA.
Water Res. 2016 Nov 15;105:187-198. doi: 10.1016/j.watres.2016.08.034. Epub 2016 Aug 21.
Wildfires can greatly alter the vegetation, soils, and hydrologic processes of watersheds serving as drinking water supplies, which may negatively influence source water quality and treatment. To address wildfire impacts on treatment, a drinking water intake below a burned watershed and an upstream, unburned reference site were monitored following the High Park wildfire (2012) in the Cache la Poudre watershed of northern Colorado, USA. Turbidity, nutrients, dissolved organic matter (DOM) character, coagulation treatability, and disinfection byproduct formation were evaluated and compared to pre-fire data. Post-fire paired spatial differences between the treatment plant intake and reference site for turbidity, nitrogen, and phosphorus increased by an order of magnitude compared to pre-fire differences. Fluorescence index (FI) values were significantly higher at the intake compared to the reference site (Δ = 0.04), and higher than pre-fire years, suggesting the wildfire altered the DOM character of the river. Total trihalomethane (TTHM) and haloacetonitrile (HAN4) formation at the intake were 10.1 μg L and 0.91 μg L higher than the reference site. Post-fire water was amenable to conventional treatment at a 10 mg L higher average alum dose than reference samples. The intake was also monitored following rainstorms. Post-rainstorm samples showed the maximum observed FI values (1.52), HAN4 (3.4 μg mg) and chloropicrin formation yields (3.6 μg mg), whereas TTHM and haloacetic acid yields were not elevated. Several post-rainstorm samples presented treatment challenges, and even at high alum doses (65 mg L), showed minimal dissolved organic carbon removal (<10%). The degraded water quality of the post-rainstorm samples is likely attributed to the combined effects of runoff from precipitation and greater erosion following wildfire. Wildfire impacts cannot be separated from rainfall effects due to the lack of post-rainstorm samples from the reference site. Results suggest for this study region, wildfire may have consequences for influent water quality, coagulant dosing, and DBP speciation.
野火会极大地改变作为饮用水供应的集水区的植被、土壤和水文过程，这可能会对水源水质和处理产生负面影响。为了应对野火对处理的影响，在美国科罗拉多州北部 Cache la Poudre 流域的 High Park 野火（2012 年）后，对一个位于燃烧流域下游的饮用水进水口和一个上游未燃烧的参考点进行了监测。评估并比较了浊度、营养物、溶解有机物质 (DOM) 特征、混凝可处理性和消毒副产物形成。与火灾前相比，火灾后处理厂进水口和参考点之间的浊度、氮和磷的成对空间差异增加了一个数量级。与参考点相比，进水口的荧光指数 (FI) 值明显更高（Δ=0.04），且高于火灾前年份，表明野火改变了河流的 DOM 特征。进水口的总三卤甲烷 (TTHM) 和卤乙腈 (HAN4) 形成量比参考点高 10.1μg/L 和 0.91μg/L。与参考样本相比，火灾后水在平均 10mg/L 更高的聚合氯化铝剂量下可进行常规处理。进水口还在暴雨后进行了监测。暴雨后水样的最大观察到的 FI 值（1.52）、HAN4（3.4μg·mg）和氯仿生成产率（3.6μg·mg）最高，而 TTHM 和卤乙酸产率没有升高。几个暴雨后水样呈现出处理挑战，即使在高聚合氯化铝剂量（65mg/L）下，也仅去除了<10%的溶解有机碳。暴雨后水样的水质恶化可能归因于降水径流和野火后更大侵蚀的综合影响。由于缺乏参考点的暴雨后样本，野火的影响无法与降雨效应分开。结果表明，在研究区域，野火可能会对进水水质、混凝剂投加量和 DBPs 形态产生影响。
