Bioaccumulation and trophic transfer of total mercury through the aquatic food webs of an African sub-tropical wetland system

Rooyen, D. van; Erasmus, Johannes H.; Gerber, R.; Nachev, Milen; Sures, Bernd; Wepener, Victor; Smit, Nico J.

doi:10.1016/j.scitotenv.2023.164210

Cited by 17 publications

(6 citation statements)

References 80 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…These artisanal activities are responsible for 35% of all Hg pollution released into the environment (UNEP 2023 ); however, the main source of Hg contamination in South Africa is the combustion of fossil fuels and aerial deposition from coal-fired power plants (Walters et al 2011 ; Erasmus et al 2022a ). Sources of Zn include industrial and mining activities and sewage effluent, as well as runoff from agricultural activities using fertilizers and insecticides (Callender 2000 ); anthropogenic sources for both Hg and Zn occur in the Sand River and this sampling location is also located in one of the main aerial transport pathways from the Mpumalanga Highveld where most of the coal-fired power plants of South Africa are situated (Erasmus et al 2022a ; van Rooyen et al 2023 ). The Vaal River has been described as one of Africa’s work horse rivers, receiving runoff and sewage effluent from three major metropolitan cities, approximately 13,600 wet industries, as well as several gold mines (Wepener et al 2011 ).…”

Section: Discussionmentioning

confidence: 65%

Element contamination of the Orange-Vaal River basin, South Africa: a One Health approach

Erasmus,

Truter,

Smit

et al. 2024

Environ Sci Pollut Res

Self Cite

View full text Add to dashboard Cite

Numerous low-income groups and rural communities depend on fish as an inexpensive protein source worldwide, especially in developing countries. These communities are constantly exposed to various pollutants when they frequently consume polluted fish. The largest river basin in South Africa is the Orange-Vaal River basin, and several anthropogenic impacts, especially gold mining activities and industrial and urban effluents, affect this basin. The Department of Environment, Forestry and Fisheries in South Africa has approved the much-anticipated National Freshwater (Inland) Wild Capture Fisheries Policy in 2021. The aims of this study were (1) to analyze element concentrations in the widely distributed Clarias gariepinus from six sites from the Orange-Vaal River basin and (2) to determine the carcinogenic and non-carcinogenic human health risks associated with fish consumption. The bioaccumulation of eight potentially toxic elements (As, Cd, Cr, Cu, Hg, Ni, Pb, Zn) was assessed in C. gariepinus from sites with different anthropogenic sources. The human health risks were determined to assess the potential risks posed by consuming contaminated C. gariepinus from these sites. Carcinogenic health risks were associated with fish consumption, where it ranged between 21 and 75 out of 10,000 people having the probability to develop cancer from As exposure. The cancer risk between the sites ranged between 1 and 7 out of 10,000 people to developing cancer from Cr exposure. A high probability of adverse non-carcinogenic health risks is expected if the hazard quotient (HQ) is higher than one. The HQ in C. gariepinus from the six sites ranged between 1.5 and 5.6 for As, while for Hg, it was between 1.8 and 5.1. These results highlight the need for monitoring programs of toxic pollutants in major river systems and impoundments in South Africa, especially with the new fisheries policy, as there are possible human health risks associated with the consumption of contaminated fish. Graphical Abstract

show abstract

Section: Discussionmentioning

confidence: 65%

Element contamination of the Orange-Vaal River basin, South Africa: a One Health approach

Erasmus,

Truter,

Smit

et al. 2024

Environ Sci Pollut Res

Self Cite

View full text Add to dashboard Cite

show abstract

“…In South Africa, in the Ga-Selati and Berg Rivers (in Limpopo basin) and Phongolo, Olifants, and Upper Vaal Rivers, concentrations of 0.036 µg/L in surface water, 50 ng/g to 1.3 µg/g in sediments, and 0.001 to 6.1 ng/g Hg in fish tissue were reported for several studies [50,74,77,78,82]. Elevated Hg concentrations ranging between 6 and 154 mg/kg were reported in stream sediments of the Farvic Gold mining area in Bulawayo, Zimbabwe [84], and between 0.006 and 154 mg/kg in the tropical reserve area in Zimbabwe [85].…”

Section: Nigeriamentioning

confidence: 95%

“…South Africa is a significant coal and Au producer in SSA and an important source of Hg pollution globally, contributing about 46.4 tonnes of Hg in 2018 [73,74]. For instance, atmospheric Hg emissions and deposition to the aquatic environment are significantly elevated in South Africa from activities such as coal combustion, ASGM, and industrial gold mining [47].…”

Section: Southern Africa South Africamentioning

confidence: 99%

“…South Africa is also the second largest producer of Au, and 70-80% of Hg emissions emanate from Au mining, far higher than coal combustion, while the remaining 20-30% is deposited onto terrestrial and aquatic environments [76]. Additionally, 50 ng/g THg and 1.3 ng/g MeHg were reported in sediment cores and surface sediments from South Africa's Berg River [77], up to 68 ng/g in the Olifants River [74], and up to 0.036 µg/L in the Ga-Selati River [78].…”

Section: Southern Africa South Africamentioning

confidence: 99%

See 1 more Smart Citation

Aquatic Mercury Pollution from Artisanal and Small-Scale Gold Mining in Sub-Saharan Africa: Status, Impacts, and Interventions

Mulenga,

Ouma,

Monde

et al. 2024

Water

View full text Add to dashboard Cite

Mercury (Hg) pollution remains an environmental global concern due to its non-degradable and toxic nature. Natural and anthropogenic sources of Hg adversely affect the functioning of aquatic ecosystems and biological processes. In sub-Saharan Africa (SSA), unregulated artisanal and small-scale gold mining (ASGM) contributes up to 20% of global gold production and uses 205–496 tonnes/yr of Hg. Despite being a vital economic driver for 20–30 million people, ASGM threatens the health of aquatic systems from Hg pollution, presenting a complex challenge that demands urgent interventions. This review seeks to (1) establish the current status of aquatic Hg pollution, (2) explore the environmental impacts of aquatic Hg, and (3) highlight the proposed interventions for aquatic Hg pollution in SSA. We examined publications and institutional reports between 2000 and 2023 addressing aquatic Hg pollution, impacts, and interventions in the ASGM of SSA. Results indicate a rise in aquatic Hg pollution due to the expansion and intensification of ASGM. West Africa remained the highest contributor (50.2%), followed by Central Africa (39.6%), Southern Africa (9.6%), and Eastern Africa (<1%). Contamination of freshwater ecosystems, toxicity to aquatic biota, and environmental health risks to humans were evident. Alternative Hg-free ASGM technologies, including physical, metallurgical, and pyrometallurgical, were investigated from case studies and recommended for adoption.

show abstract

“…Contamination can arise directly from inorganic Hg point sources, such as those along rivers (Jackson et al 2011a ; Kinghorn et al 2007 ; Nguetseng et al 2015 ; Santschi et al 2017 ; Geyer and Ralston 2018 ), around lakes (Anderson et al 2008 ; Suchanek et al 2008 ; Kumari and Maiti 2019 ; Chen et al 2021 ), and in estuaries (Eagles-Smith and Ackerman 2009 ; Chen et al 2014 ; Buckman et al 2015 ; Sullivan and Kopec 2018 ). Owing to atmospheric transport, inorganic Hg sources may not be local (i.e., <100 km) and subsequent impacts to biota are well described in most continents, including North America (Evers and Clair 2005 ; Evers et al 2011a ; Ackerman et al 2016 ; Eagles-Smith et al 2016a , b ; Evers et al 2020 ; AMAP 2021 ), South America (Sebastiano et al 2016 ; May Junior et al 2017 ; Manhães et al 2022 ), Europe (Åkerblom et al 2014 ; Nguetseng et al 2015 ; Pacyna et al 2017 ), Asia (Kim et al 2012 ; Watanuki et al 2016 ; Abeysinghe et al 2017 ; Noh et al 2017 ), Africa (Hanna et al 2015 ; van Rooyen et al 2023 ), and multiple ocean basins (Carravieri et al 2014 , 2016 ; Peterson et al 2015 ; Drevnick et al 2015 ; Lee et al 2016 ; Bodin et al 2017 ; Drevnick and Brooks 2017 ; Chastel et al 2022 ).…”

Section: Introductionmentioning

confidence: 99%

Global mercury concentrations in biota: their use as a basis for a global biomonitoring framework

Evers,

Ackerman,

Åkerblom

et al. 2024

Ecotoxicology

View full text Add to dashboard Cite

An important provision of the Minamata Convention on Mercury is to monitor and evaluate the effectiveness of the adopted measures and its implementation. Here, we describe for the first time currently available biotic mercury (Hg) data on a global scale to improve the understanding of global efforts to reduce the impact of Hg pollution on people and the environment. Data from the peer-reviewed literature were compiled in the Global Biotic Mercury Synthesis (GBMS) database (>550,000 data points). These data provide a foundation for establishing a biomonitoring framework needed to track Hg concentrations in biota globally. We describe Hg exposure in the taxa identified by the Minamata Convention: fish, sea turtles, birds, and marine mammals. Based on the GBMS database, Hg concentrations are presented at relevant geographic scales for continents and oceanic basins. We identify some effective regional templates for monitoring methylmercury (MeHg) availability in the environment, but overall illustrate that there is a general lack of regional biomonitoring initiatives around the world, especially in Africa, Australia, Indo-Pacific, Middle East, and South Atlantic and Pacific Oceans. Temporal trend data for Hg in biota are generally limited. Ecologically sensitive sites (where biota have above average MeHg tissue concentrations) have been identified throughout the world. Efforts to model and quantify ecosystem sensitivity locally, regionally, and globally could help establish effective and efficient biomonitoring programs. We present a framework for a global Hg biomonitoring network that includes a three-step continental and oceanic approach to integrate existing biomonitoring efforts and prioritize filling regional data gaps linked with key Hg sources. We describe a standardized approach that builds on an evidence-based evaluation to assess the Minamata Convention’s progress to reduce the impact of global Hg pollution on people and the environment.

show abstract

Bioaccumulation and trophic transfer of total mercury through the aquatic food webs of an African sub-tropical wetland system

Cited by 17 publications

References 80 publications

Element contamination of the Orange-Vaal River basin, South Africa: a One Health approach

Element contamination of the Orange-Vaal River basin, South Africa: a One Health approach

Aquatic Mercury Pollution from Artisanal and Small-Scale Gold Mining in Sub-Saharan Africa: Status, Impacts, and Interventions

Global mercury concentrations in biota: their use as a basis for a global biomonitoring framework

Contact Info

Product

Resources

About