Hexachlorocyclohexane and Dichlorodiphenyltrichloroethane Residues in the Dustfall of Tianjin, China

Heating and nonheating season dustfall samples were collected from 23 sites in Tianjin, China during 2002–2003 to determine residues of hexachlorocyclohexane isomers (α -HCH, β -HCH, γ -HCH, and δ -HCH) and dichlorodiphenyltrichloroethane and metabolites (p,p′-DDE, p,p′-DDD, and p,p′-DDT). Concentrations of Σ HCH (sum of α -, β -, γ -, and δ -HCH) and Σ DDT (sum of p,p′-DDE, p,p′-DDD, and p,p′-DDT) varied in ranges of 10.9–3.16 × 10³ and 37.9–1.53 × 10³ ng g^{− 1} dry weight in heating season and in ranges of 6.9–1.12 × 10³ and 18.6–626 ng g^{− 1} dry weight in nonheating season, respectively. It was found that HCHs and DDTs concentrations of the most heating season samples were higher than those of nonheating season samples collected from the same sites. Among studied compounds of the HCH family, β -HCH prevailed in most samples, suggesting a possible volatilization or resuspension from contaminated topsoil. As for DDTs, p,p′-DDT and p,p′-DDE prevailed in most samples, indicating a possible “fresh” input. Correlations between HCHs/DDTs and total organic carbon and particle size are discussed. Atmospheric deposition fluxes were calculated for the heating and nonheating seasons, and the results showed that the annual input of particulate Σ HCH and Σ DDT from air to surface in the studied area of 1.19 × 10⁴ km² were 89 t and 80 t, respectively.

Keywords:

• HCH
• DDT
• Dustfall
• Flux
• Seasonal variation

ACKNOWLEDGMENT

The research was supported by National Basic Research Program of China (grant 2003CB415004) and National Scientific Foundation of China (grants 40332015 and 40021101).