Natural archives of long-range transported contamination at the remote lake Letšeng-la Letsie, Maloti Mountains, Lesotho

Milner, Alice M.; Fitchett, Jennifer M.; Langerman, Kristy E.; Yang, Handong; Turner, Simon; Jourdan, Anne‐Lise; Shilland, James; Martins, César C.; Souza, Amanda Câmara de; Curtis, C. J.

doi:10.1016/j.scitotenv.2020.139642

Cited by 23 publications

(23 citation statements)

References 85 publications

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“…For Lesotho, the results revealed low levels of contaminants; the presence of mercury (Hg), fly ash, and polycyclic aromatic hydrocarbons (PAHs) indicate a probability of industrial fossil-fuel combustion as a source of contamination [153]. Some of the identified active chemicals in the environment of Lesotho are presented in Table 17.…”

Section: Lesothomentioning

confidence: 99%

A Review on Contaminants of Emerging Concern in the Environment: A Focus on Active Chemicals in Sub-Saharan Africa

et al. 2021

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Active chemicals are among the contaminants of emerging concern that are rarely covered in regulatory documents in sub-Saharan Africa. These substances are neither in the list of routinely monitored substances nor in the guidelines for routine environmental monitoring activities. This has been of concern to public health officials, toxicologists, communities, and governments, hence the need for risk assessment and regulation of these substances. In this review article, the presence of active chemicals in the sub-Saharan African environment was investigated. The results indicate the availability of few studies in some countries, while in other countries no reports of active chemicals were found, hence the need for further research targeting such countries. It was further observed that mixtures of active chemicals from different therapeutic categories—such as antibiotics and analgesics—were reported. The natural environment is increasingly at risk due to the presence of these substances, their metabolites, and their transformation byproducts. These substances are characterized by persistence as a result of their non-biodegradable nature; hence, they circulate from one environmental compartment to another through the food chain, causing harm along the way. Most studies that evaluated the toxicity of these substances considered the effects of a single drug, but observations indicated the presence of drug mixtures, hence the need for further evaluation of the effects of drug–drug interactions—including synergistic and additive effects—for environmental sustainability. The presence of ACs in several environmental compartments at quantifiable quantities was discovered in this investigation, indicating the potential for ecosystem injury as a result of bioaccumulation, bioconcentration, and biomagnification through the food chain. This necessitates further research on the subject in order to ensure a healthier environment.

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Section: Lesothomentioning

confidence: 99%

A Review on Contaminants of Emerging Concern in the Environment: A Focus on Active Chemicals in Sub-Saharan Africa

et al. 2021

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“…The wetland consists of a dam, surrounded by areas of temporary, seasonal and permanent wetness. The dam is in a poor state, although the water level of the dam remains high (Rose et al 2020). The wetland also forms the riverhead of the Quthing River, which is a tributary of the Senqu River, known as the Orange River downstream (in South Africa).…”

Section: Study Areamentioning

confidence: 99%

“…The average amount of rainfall is approximately 800 mm per annum (Lesotho Meteorological Services 2017). The area is also characterised by frequent snowfalls during the winter season (May to July), although the snow or sleet can occur at any time of the year (Rose et al 2020). The vegetation is classified as the Lesotho Highlands Basalt Grassland, with an azonal vegetation type (the Lesotho mires) occurring in patches within the grassland (Mucina and Rutherford 2006).…”

Section: Study Areamentioning

confidence: 99%

Assessing wetland functionality using soil surface indicators in Letšeng- la-Letsie wetland in Quthing District, Lesotho

Kahlolo

Mapeshoane

Chatanga

et al. 2021

African Journal of Range & Forage Science

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Wetlands are globally valuable ecosystems as they provide many important services to the human society, yet the ecology of some of them is yet to be understood. This study assessed the functionality of Letšeng-la-Letsie wetland in Lesotho, using the Landscape Function Analysis (LFA) technique and soil quality indicators. LFA threshold values for stability, infiltration and nutrient cycling were found to be >50%, >30% and >20%, respectively, whereas the mean surface stability, infiltration and nutrient cycling were 55.4 ± 1.9%, 28 ± 1.9%, and 15.5 ± 2% respectively. Although soil cover was high, the soil was unstable with low litter and low cryptogam cover. These rendered the soil less fertile, resulting in lower primary plant productivity and nutrient cycling potential. The three LFA indices were correlated with soil quality indicators, including pH, carbon, nitrogen, soil texture, calcium, magnesium, sodium, potassium, cation exchange capacity and phosphorus. Clay content and CEC had a significant (p < 0.05) negative correlation with the LFA indices and soil organic carbon. Redundancy analysis showed that stability was positively correlated to soil carbon and potassium. Monitoring of this wetland ecosystem is deemed necessary for the early warning of possible landscape degradation, as a result of induced pressures on the ecosystem.

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“…Although a naturally occurring, albeit short-lived (T½ = 22.3 years), radionuclide, the use of 210 Pb along with artificial radionuclides is an essential verification process for the correct age to be attributed to Anthropocene successions. Lead-210 has been used in the region independently (Kading et al, 2009;Orani et al, 2019;Tabares et al, 2020), to provide both a check for down-core changes (Das et al, 2008a;Rääf et al, 2017;Rose et al, 2020) as well as to extend 14 C dating to the present (du Plessis et al, 2020;Fontanier et al, 2018;Haberzettl et al, 2019;Stager et al, 2013;Wündsch et al, 2016).…”

Section: Radionuclidesmentioning

confidence: 99%

“…Despite this, in southern Africa there has been little consideration of the recent historical records for these contaminants or other potential indicators that might be considered markers for the Anthropocene. Indeed, stratigraphic data for these are relatively scarce (Rose et al, 2020), as they are in many regions of the southern hemisphere. Therefore, the aims of this paper are to assess the currently available evidence for Anthropocene stratigraphic markers within southern Africa and then to consider how natural archives in the region could be used to contribute to the global debate on its chronostratigraphic definition.…”

Section: Introductionmentioning

confidence: 99%

The chronostratigraphy of the Anthropocene in southern Africa: Current status and potential

Turner

Unger

Curtis

2021

South African Journal of Geology

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The process for the formal ratification of the proposed Anthropocene Epoch involves the identification of a globally isochronous stratigraphic signal to mark its starting point. The search for a Global Boundary Stratotype Section and Point (GSSP), a unique reference sequence that would be used to fix the start of the epoch, is in progress but none of the candidate sections are located in Africa. We assessed the currently available stratigraphic evidence for the possible markers of the Anthropocene in southern Africa and found that, although most markers have been identified in the region, the robustly dated, high resolution records required for the GSSP are very sparse. We then assessed the extent and stratigraphic resolution of a range of potential natural archives and conclude that a small number of permanent lakes, as well as marine sediments, corals and peats from selected locations in southern Africa could provide the temporal resolution required. With sufficient chronological control and multi-proxy analyses, one of these archives could provide a useful auxiliary stratotype thereby helping to confirm the global reach, and extending the utility, of the selected Anthropocene GSSP.

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Natural archives of long-range transported contamination at the remote lake Letšeng-la Letsie, Maloti Mountains, Lesotho

Cited by 23 publications

References 85 publications

A Review on Contaminants of Emerging Concern in the Environment: A Focus on Active Chemicals in Sub-Saharan Africa

A Review on Contaminants of Emerging Concern in the Environment: A Focus on Active Chemicals in Sub-Saharan Africa

Assessing wetland functionality using soil surface indicators in Letšeng- la-Letsie wetland in Quthing District, Lesotho

The chronostratigraphy of the Anthropocene in southern Africa: Current status and potential

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