Organochlorine pesticides and metabolites in young leaves of Mangifera indica from sites near a point source in Coast region, Tanzania

摘要

Young leaves of Mangifera indica (mango tree) from nine sites were used as bioindicators of local atmospheric contamination by orga-nochlorine pesticides and metabolites from a point source, an old storage site at Vikuge farm in Tanzania. Sample extracts were analysed by GC-ECD and GC-MS. The concentrations ranged 2.7-649 ng g~(-1) p,p'-DDT, below detection limit (bdl)-290 ng g~(-1)o,p'-DDT, 0.4-13 ng g~(-1)p,p'-DDE, bdl to 4 ng g~(-1) o,p'-DDE, 1-231 ng g~(-1) p,p'-DDD and 0.5-55 ng g~(-1)o,p'-DDD. The concentrations of other compounds were up to 3.9 ng g~(-1) pentachloroanisole, 1.3 ng g~(-1) α-HCH, 12 ng g~(-1) β-HCH and 2 ng g~(-1) γ-HCH, on fresh weight basis. The compounds p,p'-DDT, p,p'-DDE, p,p'DDD and o,p'-DDD were found in 100% of the samples, while pentachloroanisole, o,p'-DDT and o,p'-DDE were detected in 78%, 56% and 67% of the samples, respectively. The low DDE/DDT ratios (0.01-0.20) in all samples indicate recent input of significantly non-degraded DDT from the point source. The low α-/γ-HCH ratios ( < 0.3-0.7) in most samples indicate recent input of lindane (99% γ-HCH). The slightly high α-/γ-HCH ratios in some samples might be due to photochemical or bacterial transformation of γ-HCH to α-HCH, or could reflect input of technical HCH. The very strong positive correlations in the concentrations of p,p'-DDT, p,p'-DDE, p,p'-DDD, o,p'-DDT, o,p'-DDE and o,p'-DDD (r = 0.91-0.98, n = 18, p < 0.01) indicate that they have a common source. The results suggest that young mango leaves are suitable bioindicators of recent inputs of Organochlorine contaminants from a point source.