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

Keep up to date

SEGH Events

Submit Content

Members can keep in touch with their colleagues through short news and events articles of interest to the SEGH community.

Science in the News

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

  • Biochar-based constructed wetlands to treat reverse osmosis rejected concentrates in chronic kidney disease endemic areas in Sri Lanka 2017-12-01

    Abstract

    The objectives were to investigate the potential remedial measures for reverse osmosis (RO) rejected water through constructed wetlands (CWs) with low-cost materials in the media established in chronic kidney disease of unknown etiology (CKDu) prevalent area in Sri Lanka. A pilot-scale surface and subsurface water CWs were established at the Medawachchiya community-based RO water supply unit. Locally available soil, calicut tile and biochar were used in proportions of 81, 16.5 and 2.5% (w/w), respectively, as filter materials in the subsurface. Vetiver grass and Scirpus grossus were selected for subsurface wetland while water lettuce and water hyacinth were chosen for free water surface CWs. Results showed that the CKDu sensitive parameters; total dissolved solids, hardness, total alkalinity and fluoride were reduced considerably (20–85%) and most met desirable levels of stipulated ambient standards. Biochar seemed to play a major role in removing fluoride from the system which may be due to the existing and adsorbed K+, Ca+2, Mg+2, etc. on the biochar surface via chemisorption. The least reduction was observed for alkalinity. This study indicated potential purification of aforesaid ions in water which are considerably present in RO rejection. Therefore, the invented bio-geo constructed wetland can be considered as a sustainable, economical and effective option for reducing high concentrations of CKDu sensitive parameters in RO rejected water before discharging into the inland waters.

  • Medical geology of endemic goiter in Kalutara, Sri Lanka; distribution and possible causes 2017-12-01

    Abstract

    This study assesses the distribution of goiter in the Kalutara District, Sri Lanka in order to find causative factors for the occurrence of goiter even after the salt iodization. A questionnaire survey was conducted at the household level and at the same time iodine and selenium levels of the water sources were analyzed. Questionnaire survey results indicated the highest numbers of goiter patients in the northern part where the lowest were found in the southern sector which may be due to the presence of acid sulfate soils. Females were more susceptible and it even showed a transmittance between generations. Average iodine concentrations in subsurface water of goiter endemic regions are 28.25 ± 15.47 μg/L whereas non-goiter regions show identical values at 24.74 ± 18.29 μg/L. Surface water exhibited relatively high values at 30.87 ± 16.13 μg/L. Endemic goiter was reported in some isolated patches where iodine and selenium concentrations low, latter was <10 μg/L. The formation of acid sulfate soils in the marshy lands in Kalutara district may lead to transformation of biological available iodine oxidation into volatile iodine by humic substances, at the same time organic matter rich peaty soil may have strong held of iodine and selenium which again induced by low pH and high temperature were suggested as the instrumental factors in the endemic goiter in Kalutara district. Hence, geochemical features such as soil pH, organic matter and thick lateritic cap in the Kalutara goiter endemic area play a role in controlling the available selenium and iodine for food chain through plant uptake and in water.

  • Nickel accumulation in paddy rice on serpentine soils containing high geogenic nickel contents in Taiwan 2017-12-01

    Abstract

    We investigated the extractability of nickel (Ni) in serpentine soils collected from rice paddy fields in eastern Taiwan to evaluate the bioavailability of Ni in the soils as well as for demonstrating the health risks of Ni in rice. Total Ni concentrations in the soils ranged were 70.2–2730 mg/kg (mean, 472 mg/kg), greatly exceeding the natural background content and soil control standard in Taiwan. Available Ni concentration only accounts for <10% of total soil Ni content; 0.1 N HCl-extractable Ni was the more suitable index for Ni bioavailability in the soil to rice than was diethylenetriaminepentaacetic acid (DTPA)-extractable Ni. The accumulation ability of rice roots was much higher than that of its shoots; however, compared with those reported previously, our brown and polished rice samples contained much higher Ni concentrations, within the ranges of 1.50–4.53 and 2.45–5.54 mg/kg, respectively. On the basis of the provisional tolerable Ni intake for adults recommended by the World Health Organization (WHO), daily consumption of this rice can result in an excessive Ni intake.