posted on 2002-02-01, 00:00authored byKnut Breivik, Frank Wania
The POPCYCLING-Baltic model, a non-steady-state
multicompartmental mass balance model of long-term
chemical fate in the Baltic Sea environment, is used to
derive a quantitative understanding of the behavior of α-
and γ-hexachlorocyclohexane (HCH) from 1970 to 2000. The
atmosphere is found to effectively distribute the HCHs
within the Baltic Sea environment and beyond, resulting
in relatively uniform concentrations in environmental
compartments that do not directly receive emissions. This
uniformity is the result of a large-scale redistribution of
a relatively small fraction of the emitted HCHs from the
agricultural systems in source areas to all other environmental
compartments throughout the Baltic Sea region. The
major fraction of the HCHs is degraded in the soils receiving
the pesticide application. In areas where HCH-containing
pesticides are used, HCHs evaporate from soils and
water bodies and are advected away in the atmosphere.
They are deposited to forests and water bodies when they
reach remote regions. This redistribution is driven by the
inclination of the HCHs to equalize their chemical potential
within the environment, which is illustrated through the
use of fugacity fractions. The model is believed to provide
useful insight into the complex set of interactions that
determine the overall fate of an environmental contaminant
but which are inaccessible to measurements.