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Environmental Processes
The role of spring flood and landscape type in the terrestrial export of polycyclic aromatic compounds (PACs) to stream water Minh Anh Nguyen, Lutz Ahrens, Jakob Andreas Gustavsson, Sarah Josefsson, Hjalmar Laudon, and Karin Wiberg Environ. Sci. Technol., Just Accepted Manuscript • DOI: 10.1021/acs.est.7b04874 • Publication Date (Web): 24 Apr 2018 Downloaded from http://pubs.acs.org on April 24, 2018
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Environmental Science & Technology
Figure 1. Locations of the six sampling sites (red dots ●), nearby towns and cities (black squares ■) in a boreal catchment in northern Sweden (Krycklan Catchment Study area) and flow measurement site (black triangle △). 254x120mm (300 x 300 DPI)
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Figure 2. Flow (L s-1) at site C7 plotted against concentration of A) ƩPAHs (ng L-1) in the dissolved phase, B) ƩPAH-derivatives (ng L-1) in the dissolved phase, C) ƩPAHs (ng L-1) in the particulate phase, and D) ƩPAHderivatives (ng L-1) in the particulate phase at all sampling sites during the snow-covered (SnCv), spring flood (SprFl), and snow-free (SnFr) seasons from 2014 to 2016. 254x192mm (300 x 300 DPI)
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Figure 3. Ratio between the concentration at site C4 and the sum of concentrations at sites C2 and C4 for A) ∑PAHs and B) ∑PAH-derivatives in dissolved and particulate phase, respectively, during snow-free (SnFr), snow-covered (SnCv) and spring flood (SprFl) seasons in the Krycklan Catchment Study (KCS) area. A ratio > 0.5 means that the concentration at site C4 was higher than that at site C2 and vice versa. PAHs were detected only at site C4 but not at site C2 for apparently dissolved phase samples during SnFr 2014 season (black triangle (△)). Both PAHs and PAH-derivatives were detected at site C4 (but not at site C2) for particulate phase samples during SnCv 2015 season (black dots (●))
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Figure 4. Significant correlations for PAHs and PAH derivatives (ng L-1) in stream water at site C4 with upper panel showing relations to TOC and lower panel to runoff. A) Log10 TOC (mg L-1) vs. log10 ƩPAHs (n = 10), B) Log10 TOC (mg L-1) vs. log10 ƩPAH-derivatives (n = 10), C) Log10 runoff (mm day-1) vs. log10 ƩPAHs (n = 10), and D) Log10 runoff (mm day-1) vs. log10 ƩPAH-derivatives (n = 10)
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Environmental Science & Technology
The role of spring flood and landscape type in the terrestrial export of polycyclic aromatic compounds (PACs) to stream water
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Minh A. Nguyen*1, Lutz Ahrens1, Jakob Gustavsson1, Sarah Josefsson1,2, Hjalmar Laudon3, and Karin Wiberg1
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Department of Aquatic Sciences and Assessment, Swedish University of Agricultural Sciences (SLU), Box 7050, SE-75007, Uppsala, Sweden Geological Survey of Sweden, Box 670, SE-75128, Uppsala, Sweden
Department of Forest Ecology and Management, Swedish University of Agricultural Sciences (SLU), SE90183, Umeå, Sweden
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Corresponding author
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* Email:
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TOC
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Abstract
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Concentrations of polycyclic aromatic compounds (PACs), including 19 polycyclic aromatic
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hydrocarbons (PAHs) and 15 PAH-derivatives (oxygenated and nitrogen heterocyclic PAHs)
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were measured in streams in a remote headwater catchment in northern Europe and in more
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urbanized, downstream areas. Sampling was conducted during 2014 to 2016 and included the
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main hydrological seasons (snow-free, snow-covered and spring flood) at six sampling sites.
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Levels of the targeted PACs varied substantially over time and space and were up to 110-fold
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(on average 17-fold) and 7000-fold (on average 670-fold) higher for PAHs and PAH-
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derivatives, respectively, during spring flood compared with preceding snow-covered and
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snow-free seasons. Higher levels of ƩPACs were generally found in a headwater stream
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draining a mire than at an adjacent forested site, with up to 20 times and 150 times higher
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levels for ƩPAH and ƩPAH-derivatives, respectively. The particle-bound PAC levels were
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positively correlated to surface runoff in the mire stream (∑PAHs: p=0.032; ∑PAH-
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derivatives: p=0.040), but not in the corresponding forest stream, during snowmelt and winter
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base flow. In more urbanized downstream areas, particle-bound PACs were instead strongly
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associated with suspended particulate matter (p
