| Abstract
| - A survey of the contamination of the physical environmentof Costa Rica with banned organochlorine pesticides(OCPs) relied on sampling air and soil at 23 stationsacross the country in 2004. Average annual air concentrations,determined with XAD-based passive samplers, andsurface soil concentrations were generally low whencompared to values reported for North and Central America,which is consistent with relatively low historical domesticuse and little atmospheric inflow from neighboringcountries. Statistical analysis and concentration mapsreveal three types of spatial distribution: α-hexachlorocyclohexane and p,p‘-DDD had a relatively uniform distributionacross the country; other DDT-related species were greatlyelevated over the national average at Manuel Antonio, aNational Park on the Pacific coast; and dieldrin, lindane, andchlordane-related species had higher concentrations inCosta Rica's populated Central Valley. An altitudinal transectof stations in the Central Valley shows declining air−soilconcentration ratios with elevation for lindane, likely drivenby atmospheric inversions and soil organic carboncontent. Enantiomeric composition of chiral OCPs in airand soil was close to racemic, with slight depletion of (−)-α-HCH, (−)-cis-chlordane, and (+)-trans-chlordane.Estimated air−soil fugacity fractions are highly uncertainbut indicate equilibrium conditions for most OCPs, netvolatilization of lindane at some sites, and net depositionfor p,p‘-DDE. The study demonstrates an approach for quicklyevaluating the spatial distribution of OCPs in an understudiedarea, identifying regionally important contaminants andareas of elevated concentrations.
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