The impact of organochlorines cycling in the cryosphere on global distributions and fate – 2. Land ice and temporary snow cover

Global fate and transport of γ-HCH and DDT was studied using a global multicompartment chemistry-transport model, MPI-MCTM, with and without inclusion of land ice (in Antarctica and Greenland) or snow cover (dynamic). MPI-MCTM is based on coupled ocean and atmosphere general circulation models. After a decade of simulation 4.2% γ-HCH and 2.3% DDT are stored in land ice and snow. Neglection of land ice and snow in modelling would underestimate the total environmental residence time, τov, of γ-HCH and overestimate τov for DDT, both on the order of 1% and depending on actual compartmental distribution. Volatilisation of DDT from boreal, seasonally snow covered land is enhanced throughout the year, while volatilisation of γ-HCH is only enhanced during the snow-free season. Including land ice and snow cover in modelling matters in particular for the Arctic, where higher burdens are predicted to be stored.

► Land ice and snow hosts 2–4% of the global environmental burden of γ-HCH and DDT.
► Inclusion of land ice and snow cover matters for global environmental residence time.
► Including of land ice and snow cover matters in particular for the Arctic.