Characteristic trend of persistent organochlorine contamination in wildlife from a tropical agricultural watershed, South India

Abstract

The residue levels of persistent organochlorines, such as HCH (BHC: 1,2,3,4,5,6-hexachlorocyclohexane) isomers, DDT [1,1,1-trichloro-2,2-bis (p-chlorophenyl) ethane] compounds, PCBs (polychlorobiphenyls) and HCB (hexachlorobenzene), were measured in wildlife. The wildlife were sampled from terrestrial and aquatic habitats in and around the agricultural watershed of Parangipettai, South India. On the basis of overall concentrations sigma HCH ranked first followed by sigma DDT, sigma PCB and HCB, reflecting the increasing usage of HCH in recent years in India. The residue levels of organochlorines in birds varied according to their feeding habits and showed the following pattern: inland piscivores and scavengers greater than coastal piscivores greater than insectivores greater than omnivores greater than granivores. High levels of HCH and DDT residues were recorded in Pond heron and Cattle egret which feed in the agricultural fields. Comparison of HCH concentrations in fish and birds in the study area to other locations was made to further understand the dynamics of contaminant accumulation in tropical wildlife. Regarding birds, a wide variation in residue levels could be seen among various countries, with tropical regions registering high levels. In contrast, the variation is not prominent in the case of fish. The residue levels in fish measured in the present study were generally comparable to values reported from other locations. This suggests that the bioavailability of contaminants to the aquatic fauna is less due to the smaller flux and shorter residence time of these chemicals in the tropics.

Irrigation-induced pollution of organochlorine pesticides and polychlorinated biphenyls in paddy field ecosystem of Liaohe River Plain, China

“…These values were similar to the corresponding data determined in loaches (Table 1). Compared with published data, the total concentrations of HCH in mitten-handed crabs from this study was less than those in the river crab (643 ng g −1 lw) from Qiantang River of China [26], and also much less than those in mangrove crab (62 ng g −1 ww) from South India [19]. However, the mitten-handed crabs has the higher contents of HCB compared with mangrove crab from South India [19].…”

“…Therefore, the ratio of (DDD+DDE)/∑DDT is a good indicator of DDT biodegradation [19]. In this study, mitten-handed crabs had the highest average ratio of (DDD+DDE)/∑DDT of 0.97, followed by loaches (0.91) ( Figure 5).…”

“…In biotic bodies β-HCH is more stable than α-HCH and γ-HCH to enzymatic degradation [19], and thus the ratio of β-HCH/γ-HCH can reflect the degradation in organisms. As shown in Figure 5, mitten-handed crabs had the surprisingly high average ratio of β-HCH/γ-HCH of 95.0, which was 5.3 times as much as in loaches.…”

“…Mitten-handed crab and loach both have the habit to dig deep burrows in the mud, and thus they have the higher potential to accumulate the hydrophobic organic pollutants from the mud. Several studies indicated the site specific bioaccumulation of organochlorine pesticides and PCBs in crab, and suggested crab embryo as a good indicator of ecosystem health [19,20]. Therefore, a great concern should be paid to the health risk of consuming mitten-handed crab and loach cultivated in rice field.…”

Polychlorinated biphenyls and organochlorinated pesticides in birds from a contaminated region in South China: association with trophic level, tissue distribution and risk assessment

“…Significantly higher concentration of PCBs and DDTs were found in Chinese-pond heron due to its piscivorous habitat (Chang et al 2003). Previous studies have revealed that the level of organochlorine compound in piscivorous bird was higher than that in insectivore and herbivores ones (Ramesh et al 1992;Naso et al 2003). The order for the level of PCBs and DDTs among species was as follows: Chinesepond heron > white-breasted waterhen ≥ common snipe > slaty-breasted rail ≥ ruddy-breasted crake.…”