Chlordane emission

The POP protocol elaborated on occasion of the Stockholm Convention in 2001 contained 12 compounds, known as the dirty dozen aldrin, chlordane, DDT, dieldrin, endrin, heptachlor, HCB, mirex, PCBs, pol veil I orod i be nzo-/ -d i ox ins. polychlorodibenzofurans and toxaphene. After several years of implementation other compounds, were also included HCHs, PAHs, certain brominated flame retardants, perfluorooctanesulfonic acid (PFOS) and pentachlorobenzene (http // www.chem.unep.ch/pops/). This protocol is aimed to control, reduce and/or eliminate discharges, emissions and spills of POPs into the environment. 

In 1997, the United Nations Environment Programme (UNEP) Governing Council decided that immediate international action should be taken to protect human health and the environment. International negotiations to reduce and eliminate the emission and discharges of an initial set of 12 POPs were initiated at the Stockholm Convention on POPs in May 2001. The 12 substances that were addressed at the Stockholm Convention were aldrin, endrin, dieldrin, dichlorodiphenyltrichoroethanes (DDTs), polychlorinated biphenyls (PCBs), polychlorinated dibenzo-p-dioxins (PCDDs), polychlorinated dibenzofurans (PCDFs), chlordane, toxaphene, heptachlor, hex-achlorobenzene (HCB) and mirex. Basic information and status of major organochlorine pesticides in China are summarized in Table 8.1. 

The potential for OC pesticide enantiomers to be used for air-surface source apportionment was first suggested by Finizio, Bidleman, and Szeto [167], who found an air concentration gradient with the same enantiomer composition (EFs of 0.54 to 0.57 for a-HCH and 0.59 for heptachlor epoxide) up to 1.4 m above British Columbia agricultural soils with the same EFs (Figure 4.16). The subsequent measurements of nonracemic a- HCH, c/i-chlordane, and trara-chlordane in these soils [146] indicated that local and regional air burdens of these pesticides were influenced more by agricultural emissions than by trans-Pacific transport from China and India where these compounds are still... 

While agricultural soils now have nonracemic OC pesticide residues and emit these nonracemic compositions to the atmosphere, this was not necessarily always the case. Archived extracts of air samples collected in Sweden, Slovakia, and Iceland between in the early 1970s had racemic cis- and fra 5-chlordane [138]. This observation suggests that those residues were released either from fresh emissions, as these compounds were in active use at the time, and/or they were volatilized from racemic residues in soil. The former hypothesis is more likely, given the EFs of these compounds in sediment cores, which were racemic in the 1950s but less so after that point, including the 1970s [138, 139]. 

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