SEGH Articles

Geochemistry in Africa

26 January 2017
Read about VicFalls 2018 and fieldwork in the Copperbelt

Michael Watts and Elliott Hamilton returned to Africa to undertake two main tasks; (1) find a conference venue for the Society for Environmental Geochemistry 2018 international conference to be hosted in Victoria Falls, and (2) undertake fieldwork in the Zambian copperbelt as part of the Royal Society-DFID project (Royal Society-DFID project).

We met up with Dr Godfrey Sakala (Zambian Agriculture Research Institute) and Professor Florence Mtambanengwe (University of Zimbabwe) in Victoria Falls and viewed venues for hosting 150-200 people.  The location is ideally suited, with ample accommodation, conference facilities, transport connections, activities, is safe to walk around and of course the spectacle of Victoria Falls. The Falls are a must see and a gentle introduction to Africa for the uninitiated, with many National Parks close by in Zimbabwe, Zambia and Botswana.  A video was filmed to begin the promotion of the conference and signpost SEGH 2018 VicFalls which will appear on  http://segh.net/events/  shortly.

We moved onto Zambia with Dr Sakala and headed up to Kitwe in the Copperbelt to join Prof. Maseka from the Copperbelt University to follow up on previous field collections in Mugala village where field characterisation identified specific plots for experimental trials to investigate the influence of soil management strategies, such as organic incorporation, liming, low tillage (Conservation Agriculture) on the uptake of metals deposited through dust onto agricultural soils from nearby mine tailings.  Elliott Hamilton will explain more in a follow-up blog about his PhD and some of the findings so far.  Belinda Kaninga, one of our Royal Society-DFID PhD students has set out her first season field experiments as identified by the site characterisation and will bring the resultant soil and crop samples to BGS for analysis next May. 

Both Elliott and Belinda are using the same location for experimental trials, with Elliott focussing on the control parameters for Chromium (Cr) soil-to-crop transfer employing elemental speciation and isotope dilution for pot experiments using soil samples collected on this visit across the range of Cr concentrations and soil pH identified. These experiments will be undertaken at Sutton Bonington campus (University of Nottingham).  The processing of samples back in ZARI also allowed us to work with lab staff, review training needs and preparations for our upcoming purchase of Microwave-Plasma Atomic Emission Spectrometers in each of Malawi, Zambia and Zimbabwe. Meanwhile, Belinda is investigating a broad panel of metals (Pb, Cu, Zn, Cd, Mn, Al, Ni) and the application of specific Conservation Agriculture methodologies and potential influence on the availability of metals for soil-to-plant uptake.  Belinda has conducted pot trials at the ZARI research station in Lusaka, but as mentioned, recently set up her field plots in collaboration with the village chief and local farmers which will run over two growing seasons.  

A further project was initiated with Prof. Maseka and Dr Sakala to investigate the potential exposure to metals from dust inhalation from the Mugala mine tailings in the nearby village, comparing pathways of exposure from environmental samples through to biological samples from a biomonitoring collection (urine, blood).  The focus of the project will be a two-year MSc project undertaken by Lukundo Nakaona, in collaboration with the CBU Department for Environmental and Agricultural Sciences and Medical School, ZARI and BGS-UoN (CEG).  There are many other possibilities for environmental-health exposure and food security studies with our close partners at ZARI, CBU and UNZA (University of Zambia).  In particular, scope for GCRF proposals to provide capacity strengthening in technical capability to cement the strong scientific activities of our partners both in Zambia, the wider Royal Society-DFID network in Zimbabwe and Malawi and with other partners in Kenya and Tanzania.

By Michael Watts, Elliott Hamilton, Belinda Kaninga, Kenneth Maseka and Godfrey Sakala

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Latest on-line papers from the SEGH journal: Environmental Geochemistry and Health

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    Abstract

    Atrazine is one of the most widely applied and persistent herbicides in the world. In view of limited information on the regional contamination of atrazine in soils in China, this study investigated the spatial distribution and environmental impacts of atrazine in agricultural soils collected from the Yangtze River Delta (YRD) as an illustrative analysis of rapidly developing regions in the country. The results showed that the concentrations of atrazine in the YRD agricultural soils ranged from <1.0 to 113 ng/g dry weight, with a mean of 5.7 ng/g, and a detection rate of 57.7 % in soils. Pesticide factory might be a major source for the elevated levels of atrazine in Zhejiang Province. The contamination of atrazine was closely associated with land use types. The concentrations and detection rates of atrazine were higher in corn fields and mulberry fields than in rice paddy fields. There was no significant difference in compositions of soil microbial phospholipids fatty acids among the areas with different atrazine levels. Positive relationship (R = 0.417, p < 0.05, n = 30) was observed between atrazine and total microbial biomass. However, other factors, such as soil type and land management practice, might have stronger influences on soil microbial communities. Human health risks via exposure to atrazine in soils were estimated according to the methods recommended by the US EPA. Atrazine by itself in all the soil samples imposed very low carcinogenic risks (<10−6) and minimal non-cancer risks (hazard index <1) to adults and children.

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    Abstract

    α-Endosulfan and some polycyclic aromatic compounds (PAHs) are persistent in the environment and can reach crop products via contaminated agricultural soils. They may even be present as mixtures in the soil and induce mixture toxicity in soil organisms such as earthworms. In this study, the combined toxicities of PAHs with α-endosulfan were determined in Eisenia fetida adults using an artificial soil system. α-Endosulfan and five PAHs were tested for their acute toxicity toward E. fetida in artificial soils. Only α-endosulfan, fluorene, and phenanthrene showed acute toxicities, with LC50 values of 9.7, 133.2, and 86.2 mg kg−1, respectively. A mixture toxicity assay was conducted using α-endosulfan at LC10 and fluorene or phenanthrene at LC50 in the artificial soils. Upon exposure to the mixture of fluorene and α-endosulfan, earthworms were killed in increasing numbers owing to their synergistic effects, while no other mixture showed any additional toxicity toward the earthworms. Along with the acute toxicity results, the biochemical and molecular changes in the fluorene- and phenanthrene-treated earthworms with or without α-endosulfan treatment demonstrated that enhancement of glutathione S-transferase activity was dependent on the addition of PAH chemicals, and the HSP70 gene expression increased with the addition of α-endosulfan. Taken together, these findings contribute toward understanding the adverse effects of pollutants when present separately or in combination with other types of chemicals.

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    Abstract

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