1 research outputs found
Comparative Assessment of the Global Fate of α- and β-Hexachlorocyclohexane before and after Phase-Out
Technical hexachlorocyclohexane (HCH) was one of the
most widely
used pesticides during the 20th century. Although production and use
were phased-out during the 1990s, two of its major components, α-
and β-HCH, are still ubiquitous in the environment. Here, we
have collected and analyzed data on concentrations of α- and
β-HCH in the atmosphere and oceans, including spatial and temporal
trends and seasonalities. We apply a global fate and transport model
to both isomers over the period 1950 to 2050 to rationalize current
levels and trends at remote locations with estimated emissions and
to forecast into the near future. Our model results indicate that
secondary emissions from soils and oceans are currently controlling
the observed rates of decline in the atmosphere. β-HCH is declining
more slowly than α-HCH due to its higher persistence, and we
hypothesize that it will eventually become the predominant isomer
of HCH in the environment. The model reproduces over 70% of measured
concentrations of α-HCH in air and ocean water within factors
of 3 and 5, respectively, and over 70% of measured concentrations
of β-HCH within factors of 8 and 20, respectively. The model
results are only weakly sensitive to climate change-induced trends
in Arctic sea-ice cover and temperature