Abstract
Organochlorine pesticides (OCPs) were analysed in surface water, pore water and surface sediment samples collected from the uMngeni River, which is one of the largest rivers in the province of KwaZulu-Natal, South Africa. Liquid-liquid extraction was used to extract the analytes from water and pore water samples and soxhlet extraction was used to extract sediment samples with subsequent florisil clean-up and gas chromatography-mass spectrometry (GC-MS) analysis. Twelve selected OCPs were analysed and their total concentrations were found to range from 8.04–21.06 ng/mL, 36.06–188.43 ng/mL and 148.17–554.73 ng/g in unfiltered surface water, unfiltered pore water and surface sediment (dry weight (dw)), respectively. The results indicated that the concentrations of these selected pesticides were far higher in sediment (72%) than in pore water (25%) and water (3%). The most polluted sites were Northern Wastewater Treatment influent (NWTI) for water (Σ12 OCP = 19.41 ± 1.43 ng/mL) and Northern Wastewater Treatment effluent (NWTE) for pore water (Σ12 OCP = 166.23 ± 7.16 ng/mL) and sediment (Σ12 OCP = 495.21 ± 32.38 ng/g). The most abundant individual OCPs and their average concentrations in general in the river were p,p′-DDE in unfiltered water (1.62 ±0.22 ng/mL) and unfiltered sediment pore water (17.09 ±7.96 ng/mL), and endrin in surface sediment (55.57 ± 19.01 ng/g, dw).
Highlights
Pesticides are agrochemicals extensively used in agriculture and public health sectors to control or mitigate pests causing crop damage and diseases
The present study has provided data on levels of organochlorine pesticides in surface water, sediment pore water and sediments of the uMngeni River in KwaZulu-Natal, South Africa
All 12 selected pesticides investigated were detected at all sites, in water, pore water and sediment, except aldrin which was below the limit of detection in water at the Reservoir Hills sampling site
Summary
Pesticides are agrochemicals extensively used in agriculture and public health sectors to control or mitigate pests causing crop damage and diseases. Their main properties include low polarity, low aqueous solubility and high lipophilicity. As a result, they bioaccumulate and bioamplify through the food chain and are a threat to the environment and to human health (Afful et al, 2010; ZhaO et al, 2013; Zhao et al, 2009). Researchers have found that organochlorine pesticides and their metabolites may cause chronic toxicity to humans and animals through air, water and food intake (Dong-hui and Guang-xing, 2012; Rachid et al, 2012). OCPs have been banned in many countries since the 1970s but are still detected in water, sediments, air and aquatic biota today, because of their persistence in the environment (Fox et al, 2001; Albaiges et al, 1987; Iwata et al, 1994; Hogarh et al, 2014)
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