Human activity dramatically changes the chemosphere through contribution of synthetic compounds as well as unnatural mobilization processes such as industrial scale hydrocarbon extraction, combustion and agriculture. Millions of man-made chemicals have been synthesized, of
Many legacy and emerging persistent
organic pollutants (POPs) have
been reported in polar regions, and act as sentinels of global pollution.
Maritime Antarctica is recipient of abundant snow precipitation. Snow
scavenges air pollutants, and after snow melting, it can induce an
unquantified and poorly understood amplification of concentrations
of POPs. Air, snow, the fugacity in soils and snow, seawater and plankton
were sampled concurrently from late spring to late summer at Livingston
Island (Antarctica). Polychlorinated biphenyls (PCBs) and organochlorine
pesticides (OCPs) concentrations in snow and air were close to equilibrium.
POPs in soils showed concentrations close to soil–air equilibrium
or net volatilization depending on chemical volatility. Seawater–air
fugacity ratios were highly correlated with the product of the snow–air
partition coefficient and the Henry’s law constant (K
SA H’), a measure of snow amplification
of fugacity. Therefore, coastal seawater mirrored the PCB congener
profile and increased concentrations in snowmelt due to snowpack releasing
POPs to seawater. The influence of snowpack and glacier inputs was
further evidenced by the correlation between net volatilization fluxes
of PCBs and seawater salinity. A meta-analysis of K
SA, estimated as the ratio of POP concentrations in snow
and air from previously reported simultaneous field measurements,
showed that snow amplification is relevant for diverse families of
POPs, independent of their volatility. We claim that the potential
impact of atmospheric pollution on aquatic ecosystems has been under-predicted
by only considering air–water partitioning, as snow amplification
influences, and may even control, the POP occurrence in cold environments.
Scavenging of gas-
and aerosol-phase organic pollutants by rain
is an efficient wet deposition mechanism of organic pollutants. However,
whereas snow has been identified as a key amplification mechanism
of fugacities in cold environments, rain has received less attention
in terms of amplification of organic pollutants. In this work, we
provide new measurements of concentrations of perfluoroalkyl substances
(PFAS), organophosphate esters (OPEs), and polycyclic aromatic hydrocarbons
(PAHs) in rain from Antarctica, showing high scavenging ratios. Furthermore,
a meta-analysis of previously published concentrations in air and
rain was performed, with 46 works covering different climatic regions
and a wide range of chemical classes, including PFAS, OPEs, PAHs,
polychlorinated biphenyls and organochlorine compounds, polybromodiphenyl
ethers, and dioxins. The rain–aerosol (K
RP) and rain–gas (K
RG) partition
constants averaged 105.5 and 104.1, respectively,
but showed large variability. The high field-derived values of K
RG are consistent with adsorption onto the raindrops
as a scavenging mechanism, in addition to gas–water absorption.
The amplification of fugacities by rain deposition was up to 3 orders
of magnitude for all chemical classes and was comparable to that due
to snow. The amplification of concentrations and fugacities by rain
underscores its relevance, explaining the occurrence of organic pollutants
in environments across different climatic regions.
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