Heptachlor 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... 

Figure 4.16 Gas chromatogram traces of the enantiomers ofa-HCH, heptachlor (HEPT), and heptach lor epoxide (HEPX) in soil and overlying air at a British Columbia farm. (Reproduced with permission from Chemosphere, Emission of chiral pesticides from an agricultural soil in the Eraser Valley, British Columbia, by A. FInIzIo, T. F. Bldleman and S. Y. Szeto, 36(2), 345-355. Copyright...

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