Department of Physical and Environmental Sciences, University of Toronto Scarborough, 1265 Military Trail, Toronto, Ontario, M1C 1A4, Canada.
Department of Physical and Environmental Sciences, University of Toronto Scarborough, 1265 Military Trail, Toronto, Ontario, M1C 1A4, Canada; Department of Chemical Engineering and Applied Chemistry, University of Toronto, 200 College Street, Toronto, Ontario, M5S 3E5, Canada.
Water Res. 2017 Nov 1;124:407-414. doi: 10.1016/j.watres.2017.07.074. Epub 2017 Jul 31.
Though it has been established that stream concentrations of polycyclic aromatic hydrocarbons (PAHs) in urban watersheds can be much greater than those in less developed watersheds, knowledge of transport mechanisms is lacking, particularly in temperate, Northern climates with seasonal snow packs. We combine high-resolution stream water sampling with air, suspended solid and stream flow monitoring to investigate the source to stream transport of PAHs during rainfall and snowmelt in paired watersheds with contrasting land use. Despite similar particle loads, contamination of particles that is 8-48 times higher in the urban watersheds leads to area-normalized loads of PAHs that are 6-82 times greater than in the agricultural watersheds. In the urban watershed, average volumetric storm flow concentrations increase with longer antecedent dry period that allows build-up of PAHs on watershed surfaces. Cluster analysis suggests road dust is a minor source of suspended solid-bound PAHs in more agricultural watersheds during rainfall. During snowmelt, earlier peaks in concentration in the urban watershed are likely due to melt from snow packs and snow banks travelling quickly to the stream network via impervious surfaces and sewer drains. While road-derived inputs also appear to be important during snowmelt in the agricultural watershed, relatively delayed peak concentrations result from delayed inputs from snow packs in more pervious areas of the watershed.
尽管已经证实城市流域中多环芳烃 (PAHs) 的溪流浓度可能远高于欠发达流域，但对于传输机制的了解却很欠缺，特别是在具有季节性积雪的温带、北方气候中。我们结合高分辨率的溪流水样采集以及空气、悬浮固体和溪流流量监测，在具有不同土地利用的成对流域中，调查降雨和融雪期间 PAHs 的源到溪流的传输。尽管颗粒负荷相似，但在城市流域中污染颗粒的浓度要高出 8-48 倍，导致归一化到流域面积的 PAH 负荷比农业流域高出 6-82 倍。在城市流域中，随着较长的前期干燥期允许 PAHs 在流域表面积聚，平均体积风暴流浓度会增加。聚类分析表明，在更多的农业流域中，降雨期间，道路灰尘是悬浮固体结合态 PAHs 的次要来源。在融雪期间，城市流域中浓度较早出现峰值可能是由于雪包融化以及通过不透水表面和污水渠快速流向溪流网络的雪堤导致的。虽然在农业流域的融雪期间，道路衍生的输入似乎也很重要，但在流域更透水的区域，由于雪包的输入延迟，导致浓度峰值相对延迟。
