es6b00475_si_001.pdf (1.6 MB)
Persistent Organic Pollutants in Streamwater: Influence of Hydrological Conditions and Landscape Type
journal contribution
posted on 2016-06-23, 00:00 authored by Sarah Josefsson, Magnus Bergknut, Martyn N. Futter, Stina Jansson, Hjalmar Laudon, Lisa Lundin, Karin WibergConcentrations
of polychlorinated dibenzo-p-dioxins
and dibenzofurans (PCDD/Fs), polychlorinated biphenyls (PCBs), and
hexachlorobenzene (HCB) in streamwater were measured in a remote catchment
in northern Sweden and downstream to the Baltic Sea. Sampling took
place at seven sites during two years and under different hydrological
conditions: during the snow-free, snow-covered, and spring-flood seasons.
Concentrations varied substantially between seasons and were up to
20 times higher during the spring flood compared to the preceding
snow-covered period. The increase in concentrations with runoff was
due to higher levels of particle-associated contaminants, while the
dissolved concentrations remained stable. Particulate-contaminant
concentrations were positively correlated primarily to suspended particulate
matter (SPM) at sites in areas with a high land-cover fraction of
sorted sediment. When upstream sampling locations were compared, a
mire-dominated stream had higher concentrations and a lower retention
of atmospherically deposited contaminants than a forest stream of
the same catchment size. Contaminant concentrations (normalized to
volume) did not increase consistently downstream despite the presence
of several point sources. However, when normalized to the amount of
SPM, concentrations were on average >20 times higher at the outlet
in the Baltic Sea compared to the outlet from the remote catchment
without point sources.