Contamination Pattern and Risk Assessment of Polar Compounds in Snow Melt: An Integrative Proxy of Road Runoffs

To assess the contamination and potential risk of snow
melt with
polar compounds, road and background snow was sampled during a melting
event at 23 sites at the city of Leipzig and screened for 489 chemicals
using liquid chromatography high-resolution mass spectrometry with
target screening. Additionally, six 24 h composite samples were taken
from the influent and effluent of the Leipzig wastewater treatment
plant (WWTP) during the snow melt event. 207 compounds were at least
detected once (concentrations between 0.80 ng/L and 75 μg/L).
Consistent patterns of traffic-related compounds dominated the chemical
profile (58 compounds in concentrations from 1.3 ng/L to 75 μg/L)
and among them were 2-benzothiazole sulfonic acid and 1-cyclohexyl-3-phenylurea
from tire wear and denatonium used as a bittern in vehicle fluids.
Besides, the analysis unveiled the presence of the rubber additive
6-PPD and its transformation product N-(1.3-dimethylbutyl)-N′-phenyl-p-phenylenediamine quinone
(6-PPDQ) at concentrations known to cause acute toxicity in sensitive
fish species. The analysis also detected 149 other compounds such
as food additives, pharmaceuticals, and pesticides. Several biocides
were identified as major risk contributors, with a more site-specific
occurrence, to acute toxic risks to algae (five samples) and invertebrates
(six samples). Ametryn, flumioxazin, and 1,2-cyclohexane dicarboxylic
acid diisononyl ester are the main compounds contributing to toxic
risk for algae, while etofenprox and bendiocarb are found as the main
contributors for crustacean risk. Correlations between concentrations
in the WWTP influent and flow rate allowed us to discriminate compounds
with snow melt and urban runoff as major sources from other compounds
with other dominant sources. Removal rates in the WWTP showed that
some traffic-related compounds were largely eliminated (removal rate
higher than 80%) during wastewater treatment and among them was 6-PPDQ,
while others persisted in the WWTP.