Atmospheric PAHs transfers in an alpine river

Atmospheric PAHs transfers in an alpine river: The Arc River
Johanna Marçais1, Christine Piot1, Philippe Fanget1, Julien Némery2, Fabien Thollet3,
Emmanuel Naffrechoux1 and Jean-Luc Besombes1.
1
Université Savoie Mont-Blanc, Laboratoire de Chimie Moléculaire et Environnement (LCME), 73376 Le
Bourget du lac, France.
2 Université Grenoble Alpes, Laboratoire d’étude des Transferts en Hydrologie et Environnement (LTHE),
CNRS IRD, 38000 Grenoble, France.
3 Institut National de Recherche en Sciences et Technologies pour l’Environnement et l’Agriculture (IRSTEA),
Unité de Recherche Hydrologie Hydraulique, 69626 Villeurbanne, France.
Atmospheric Polycyclic Aromatic Hydrocarbons (PAHs) are eliminated by dry
(aerosol) or wet (rain, snow) depositions and may impact remote area like mountain’s
aquatic ecosystems [1].
In the present work, transfer from atmosphere to river water was studied for 15
PAHs in the Maurienne Valley (French Alps) from spring 2014 to spring 2015. Three
sites were selected along the river to follow upstream/downstream transfer dynamic.
Silicone rubbers were used as passive samplers for dissolved PAHs in the river
water with a 1-month sampling period. Particulate PAHs were quantified by river
suspended solids sampling with automatic samplers in an integration mode. A low
volume air sampler was used to collect gaseous PAHs and atmospheric particles.
PAHs bulk deposits were also sampled with a deposition gauge equipped with an
XAD-2 resin column.
A first sampling in autumn 2013 shows that PAHs partition in the river water was
not the same between upstream and downstream along the valley. Upstream, 83% of
total PAHs were in the dissolved phase (17% in the particulate phase) against 13%
downstream (87% as particulate PAHs). This first result supports the hypothesis of a
modified PAH transport or different PAH sources along the valley. PAHs concentration
and phase distribution in the river water will be compared to PAHs concentration and
phase distribution in the atmosphere and bulk deposits, in order to determine the
more realistic assumption.
Keywords: PAHs, alpine river, air-water transfers
[1] R. M. Vilanova, P. Fernández, C. Martı́nez, et J. O. Grimalt, « Polycyclic aromatic hydrocarbons in
remote mountain lake waters », Water Res., vol. 35, no 16, p. 3916‑3926, nov. 2001.