Organochlorine pesticide contamination in sediments from Richards Bay, South Africa: spatial trends and ecotoxicological risks

Abstract

The occurrence and distribution of organochlorine pesticides (OCPs) in aquatic systems is a matter of global concern and poses significant toxicological threats to both organisms and human health. Despite the extensive use of OCPs for pest and disease control in southern Africa, relatively few studies have examined the occurrence and toxicological risks of OCP residues in the region. This study investigates the composition, distribution, and potential sources of OCP contamination in sediments from Richards Bay, a rapidly developing industrial port on the northeast coast of South Africa. Surface sediments collected from Richards Bay Harbour and surrounding areas indicate that OCP contamination in the region is widespread. Total concentrations (∑OCP) in surface samples ranged from 135 to 1020 ng g−1, with hexachlorocyclohexanes (∑HCH; 35–230 ng g−1) and dichlorodiphenyltrichloroethanes (∑DDT; 12–350 ng g−1) the dominant contaminant groups detected. Metabolite isomeric compositions indicate that the presence of aldrin and endosulfan likely result from historical agricultural usage, while recent input of γ-HCH, heptachlor, and endrin may be linked to the illegal use of old pesticide stockpiles. Total DDT concentrations were dominated by p,p′-DDT (80 ± 64 ng g−1), which was attributed to its ongoing use in malaria vector control in the region. A 210Pb-dated sediment core revealed that OCP input to the local environment increased dramatically from relatively low concentrations in the mid-1940s (∑OCP, 355 ng g−1) to peak levels (∑OCP, 781 ng g−1) in the 1980s/1990s. An overall decrease in ∑OCP concentration from the mid-2000s is likely related to restrictions on use following the Stockholm Convention in 2004. Despite current restrictions on use, OCP concentrations exceeded sediment quality guidelines in the vast majority of cases, raising concerns for protected estuarine and mangrove habitats in the area, as well as for local fishing and farming communities.

The Status of Marine Mussel Pollution Research in South Africa (2012–2022)

“…Research into the POP contamination of non-mussel species is increasingly prevalent within South Africa, with local studies investigating these contaminants in beached polyethylene pellets [128], chokka squid (Loligo reynaudii) [129], great white sharks (Carcharodon carcharias) [130], albacore tuna (Thunnus alalunga) [131], various dolphin species [132], waters and fish from multiple estuaries [133][134][135][136], the waters and sediments of Algoa Bay [137,138], and sediments from Richard's Bay [139,140]. The results of the literature search showed that POP contamination research within South Africa is present but often limited in scope, occurring on only one species at a time or within a small sampling area.…”

Residual behavior and risk assessment of fluopyram, acetamiprid and chlorantraniliprole used individually or in combination on strawberry

“…Pesticides are unavoidably employed in agricultural production practices to increase product quality and productivity. The indiscriminate, frequent application of pesticides frequently result in pesticide residues in crops exceeding limits, raising the dietary risk to consumers (Balkan and Yılmaz, 2022;Khazaal et al, 2022;Nougadère et al, 2012;Tang et al, 2021;Huang et al, 2021;Mehlhorn et al, 2022). Strawberries in greenhouses due to the high temperature and humidity are particularly vulnerable to pests (Botrytis cinerea, Chaetosiphon fragaefolii, Colletotrichum and Frankliniella occidentalis) and diseases (gray mold and powdery mildew) (Li et al, 2022a;Van Oystaeyen et al, 2022;Wang et al, 2022a;Yan et al, 2021).…”