Bimonthly variability of persistent organochlorines in plastic pellets from four beaches in Mumbai coast, India

Organochlorines (OCs) such as polychlorinated biphenyls (PCBs) and organochlorine pesticides (OCPs) were analysed in plastic pellets collected from four beaches of Mumbai coast bimonthly from May 2011 to March 2012. A total of 72 pools of pellets were extracted and analysed by gas chromatograph equipped with a Ni(63) electron capture detector (ECD). The median concentrations of seven ΣPCBs and 16 ΣOCPs were 37.08 and 104.90 ng g(-1) (n = 72), respectively. PCB-28 was recorded at the highest concentration with a mean of 17.58 ± 2.77 ng g(-1) among the seven PCBs studied, followed by PCB-52 and PCB-101. Bimonthly variation was significant for ΣPCBs. The ΣPCB concentration in November was at par with that of September and was significantly higher than those of the other months (p < 0.05) with an increasing trend during the monsoon period. Among the OCPs, γ-HCH recorded the highest concentration with a mean of 33.88 ± 5.97 ng g(-1) followed by heptachlor and α-HCH. The ΣOCPs and ΣHCHs are not significantly varied among the months and sites. However, significant variation was observed for ΣDDTs among the months and sites (p < 0.05). The significantly higher concentration of ΣDDT (46.55 ± 12.23 ng g(-1)) was found in January than in the other months while it was intermediate in November. The study confirmed that plastic pellets are a trap for various cyclodine compounds in addition to PCB, HCH and DDT. Further, pellets can be used to study the temporal variability for a range of organic micropollutants.