Investigation of Selected Organic Compounds Influence on Water Quality Along the Olifants River in South Africa

Abstract

Water is a crucial natural resource, indispensable to food production, life, the environment, power generation, industry, sanitation and hygiene. Organochlorine Pesticides (OCPs) in the environment are not wanted due to their negative effects on human beings and animals. As a result, there is a need to continuously monitor their presence in the environment. In this study, surface water samples were collected once a month during the dry season and during wet season from selected five points along the Olifants river in South Africa and stored at a temperature of ≤ 5°C before analysis. The OCPs were extracted with dichloromethane (DCM) using the Liquid-Liquid Extraction (LLE) method. After undertaking the sample through the clean-up process, the crude extracts obtained were put into the column chromatography and eluted with hexane and about 1.5 µL of the purified extracts were analysed by the Gas Chromatographic-Mass Spectrophotometer (GC/MS).The percentage recoveries, varied from 32-116% for p,p'-DDT and 4,4'-DDD respectively in triply spiked water samples. The standard deviation for most of the compounds is less than ± 0.04, with the exclusion of Heptachlor (± 0.14). The seasonal variability of OCPs show that during the dry season, the Olifants River is mostly polluted at the Oxford site with (BHC-beta, Aldrin, Heptachlor-epoxide, Endosulfan-alpha and Endrin), at the Ga-Selati site with (Heptachlor-epoxide and Endrin) and at the Wolvekrans site with (Endosulfan-alpha). The summer season data show that most pollution happen at the Ga-selati site with BHC-beta and at the Waterval site with (Heptachlor and BHC-gamma) respectively. The OCPs that reached the river catchment were significantly above the WHO drinking water quality guidelines and its cause for concern for those who are exposed or use it.

Temporal and spatial variations of organochlorine pesticides (OCPs) and phthalates affecting the quality of water and sediment from Loskop Dam, South Africa

“…The linearity of calibration data was assessed by applying the regression analysis model in the Analysis Toolpak of Excel. The resulting least square estimates were used to calculate the limits of detection and quantification (LOD and LOQ) (Miller and Miller, 2010;Shrivastava and Gupta, 2011). Data were further subjected to analysis of variance (ANOVA), descriptive statistics, correlation plots and multivariate methods.…”

“…Furthermore, the seasonal changes were also expected, since these correlate with increases and/or decreases in water levels, variations in climatic conditions, which may be exacerbated by run-off, as well as differences in anthropogenic activities (Montory et al, 2017;Baqar et al, 2018;Wang et al, 2018). Moja et al (2017) found that the site closest to Loskop Dam, namely Waterval, demonstrated seasonal variability in pesticide levels. Similar temporal and spatial observations have also been made in other water bodies (Montory et al, 2017;Baqar et al, 2018;Wang et al, 2018).…”

“…Sporadic crocodile and fish deaths, which remain unexplained, have occurred in this water body (Huchzermeyer et al, 2013). Previous studies have demonstrated that anthropogenic input is the key driver of contamination in the entire Olifants catchment area (Gerber et al, 2016;Seopela et al, 2016;Moja et al 2017). In this study, spatial and temporal variations in OCPs and phthalates in water and sediment from the Loskop Dam were evaluated to determine their contribution to the contamination of this water body.…”

“…These compounds have been reported to induce neurotoxic effects in organisms (USEPA, 2012;ECHA, 2018;UNEP, 2018). The heavy reliance on OCPs, currently and historically, to enhance agricultural production and as a vector method for disease control, has exacerbated their presence in, and impact on, the environment (Gerber et al, 2016;Moja et al, 2017;UNEP, 2018). Ansara-Ross et al (2012) provides a chronological account of pesticide use in South Africa and noted that fewer than 50 studies on environmental contamination by OCPs had been conducted in South Africa by 2012.…”

“…Tissue and fat from fish collected in these water systems contained up to 14.670 μg/kg of total OCPs. In recent studies, bioaccumulation, trophic level transfer and increases in the levels of these compounds in South African aquatic systems have been demonstrated (Gerber et al, 2016;Moja et al, 2017).…”