SEGH Articles

The Joy's of PhD research in two countries

06 October 2014
Edwards project aim is to improve the accuracy and spatial resolution of dietary mineral supply estimates in Malawi and to investigate the potential of agricultural solutions to mitigate dietary mineral deficiencies. He has been conducting fieldwork in Malawi during 2012-14.

Humans require 22 mineral elements for their wellbeing including calcium (Ca), iron (Fe), magnesium (Mg), selenium (Se) and zinc (Zn). The biological functions of elements include bone structure (Ca and Mg) and, as constituents of proteins, immune response (Se and Zn) and oxygen transport (Fe and Zn). Adequate quantities of these elements in diets is thus necessary for food security; inadequate intakes, or poor absorption in the gut due to e.g. diarrhoea, can lead to ‘hidden hunger’. It’s termed ‘hidden’ because the physical effects are not obvious, unlike the symptoms of protein or energy undernourishment, and because it is often hard to quantify the prevalence of such malnourishment in populations.

Malawi hasn’t witnessed widespread famine since 2005, although certain regions are prone to food shortages due to both drought and flooding. But it may be that hidden hunger is widespread and that deficiencies of certain minerals and vitamins are a major health burden. There is evidence to suggest this is the case, for example with Se deficiency (Gibson 2011; Eick 2009; Hurst 2013) and Zn deficiency (Gibson 1998; Siyame 2013); but there is no data at the national level.

Malawi is predominantly a subsistence economy in which households grow their own food. The dietary supply of elements is thus dependent on which crops households choose to grow and what those crops contain. Element concentrations in crops depend on the availability of elements in the soil: for example, in low-pH soils Se is predominantly found in forms unavailable for plant uptake, whereas in soils with pH >6.5 Se is generally soluble, mobile and readily available for plant uptake.  There are limited data on crop composition in Malawi so we worked to fill this gap, collecting over 600 crop samples representing 97 food items for multi-element analysis by ICP-MS (Joy et al. submitted). We found that soil type affects crop composition, with maize and leafy vegetables from calcareous soils having greater Ca, Cu, Fe, Mg and Se concentrations than those grown on non-calcareous soils. Maize also had greater Zn in samples from calcareous soils, whereas leafy vegetables had greater Zn from non-calcareous soils.

To find out what crops households are growing and what foods they are eating, the Malawi Household Survey (World Bank and Malawi Government) has proved a valuable resource. In this survey, >12,500 households were asked what foods they consumed over the last seven days. We are working to match this data to our composition data to generate dietary mineral supply estimates by region and soil type. One of our early findings is the critical importance of small fish in meeting Ca, Se and Zn requirements. Most fish production is from Lake Malawi, a Rift Valley lake that runs much of the length of the country. It’s sometimes known as the Calendar Lake as it’s roughly 365 mile long and 52 miles wide. Fish are sundried before traders take them inland. Although fish is a vital source of minerals in the diet, households require some cash to purchase them. It will be very interesting to see the relationship between household income and consumption of fish. 

Dried fish at a market in the capital city, Lilongwe


The FAO and World Bank have just published a book called ‘Analyzing Food Security Using Household Survey Data’ ( and at the recent Micronutrient Forum held in Addis Ababa, Ethiopia, I found that other research groups including IFPRI are doing similar work to us. It’s great to see the hard work now contributing to scientific knowledge as we write up, publish and present our findings.

Edward presenting the team’s work at Mzuzu University in northern Malawi


The last couple of years have been a steep learning curve: a faulty radiator can write off your engine; laptop battery life is everything; and you may need to hire guards to keep monkeys off your maize trials! These have been valuable lessons as I plan to continue similar research in Ethiopia starting in September. Overall it has been a pleasure living in Malawi, a country endowed with some very beautiful landscapes and incredibly friendly folk – it’s not uncommon on sampling trips to be invited into farmers’ houses for roast pumpkin and peanuts. And the Malawi Ministries of Agriculture and Health have been very supportive of the work. Hopefully the outputs will be useful to them, for example in developing fertiliser policies and targeting nutrition strategies.


by Edward Joy, PhD researcher University of Nottingham-BGS


Eick F, Maleta K, Govasmark E, Duttaroy AK, Bjune AG (2009) Food intake of selenium and sulphur amino acids in tuberculosis patients and healthy adults in Malawi. Int J Tuberc Lung Dis 13: 1313–1315

Gibson RS, Bailey KB, Ampong Romano AB, Thomson CD (2011) Plasma selenium concentrations in pregnant women in two countries with contrasting soil selenium levels. J Trace Elem Med Bio 25:230–235

Gibson RS, Huddle JM (1998) Suboptimal zinc status in pregnant Malawian women: its association with low intakes of poorly available zinc, frequent reproductive cycling, and malaria. Am J Clin Nutr 67:702–709

Hurst R, Siyame EWP, Young SD, Chilimba ADC, Joy EJM, Black CR, Ander EL, Watts MJ, Chilima B, Gondwe J, Kang’ombe D, Stein AJ, Fairweather-Tait SJ, Gibson RS, Kalimbira AA, Broadley MR (2013) Soil-type influences human selenium status and underlies widespread selenium deficiency risks in Malawi. Sci Rep 3: 1425. DOI: 10.1038/srep01425

Siyame EWP, Hurst R, Wawer AA, Young SD, Broadley MR, Chilimba ADC, Ander EL, Watts MJ, Chilima B, Gondwe J, Kang'ombe D, Kalimbira A, Fairweather-Tait SJ, Bailey KB, Gibson RS (2013) A high prevalence of zinc- but not iron-deficiency among women in rural Malawi: a cross-sectional study. Int J Vitam Nutr Res 83: 176–187

Joy, EJM, Broadley, MR, Young, SD, Black CR, Chilimba, ADC, Ander, EL, Barlow, TS and Watts, MJ*. (2014). A spatially refined food composition table for Malawi, Science Total Environment, (in press)



Keep up to date

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

  • Date palm waste biochars alter a soil respiration, microbial biomass carbon, and heavy metal mobility in contaminated mined soil 2017-04-19


    A 30-day incubation experiment was conducted using a heavy metal-contaminated mined soil amended with date palm feedstock (FS) and its derivative biochars (BCs) at three pyrolysis temperatures of 300 (BC-300), 500 (BC-500), and 700 °C (BC-700) with different application rates (0.0, 5, 15, and 30 g kg−1) to investigate their short-term effects on soil respiration (CO2–C efflux), microbial biomass carbon (MBC), soil organic carbon (SOC), mobile fraction of heavy metals (Cd, Cu, Pb, Zn, Mn, and Fe), pH, and electrical conductivity (EC). The results showed that FS and BC-300 with increasing addition rate significantly reduced soil pH, whereas SOC, CO2–C efflux, and soil MBC were increased compared to the control. On the contrary, BC-500 and BC-700 increased soil pH at early stage of incubation and have small or no effects on SOC, CO2–C efflux, and MBC. Based on the results, the date palm biochars exhibited much lower cumulative CO2–C efflux than feedstock, even with low-temperature biochar, indicating that BCs have C sequestration potential. Applying BC-700 at 15 and 30 g kg−1 significantly reduced cumulative CO2–C efflux by 21.8 and 45.4% compared to the control, respectively. The incorporation of FS into contaminated soil significantly increased the mobile content of Cd and Mn, but decreased the mobile content of Cu. However, BC-300 significantly reduced the mobile content of Cd, Cu, Pb, and Zn. It could be concluded that low-temperature biochar could be used as a soil amendment for reducing heavy metal mobility in mining contaminated soil in addition to minimize soil CO2–C efflux.

  • Historical record of anthropogenic polycyclic aromatic hydrocarbons in a lake sediment from the southern Tibetan Plateau 2017-04-17


    High-altitude lake sediments can be used as natural archives to reconstruct the history of pollutants. In this work, the temporal distribution of polycyclic aromatic hydrocarbons (PAHs) was determined in a sediment core collected from the southern Tibetan Plateau (TP), which was dated by using the 210Pb dating method and validated with the 137Cs fallout peak. The concentrations of the anthropogenic PAHs (Σ8PAH) in the sediment core ranged from 0.83 to 12 ng/g dw, and the fluxes of the Σ8PAH were in the range of 2.1–27 g/cm2/year. The temporal variations in the concentration and input flux of anthropogenic PAHs were low with little variability before the 1950s, and then gradually increased from the 1950s to the 1980s, and an accelerated increase was observed after the early 1980s. The content of total organic carbon played an insignificant role in affecting the time trends of PAHs in the sediment core. Diagnostic concentration fractions of PAH components indicate PAHs in the lake sediment of the southern TP which are mainly from biomass burning and/or from long-range atmospheric transport.

  • Determination of the potential implementation impact of 2016 ministry of environmental protection generic assessment criteria for potentially contaminated sites in China 2017-04-12


    The Ministry of Environmental Protection of China issued a 3rd draft edition of risk-based Generic Assessment Criteria (the MEP-GAC) in March 2016. Since these will be the first authoritative GAC in China, their implementation is likely to have a significant impact on China’s growing contaminated land management sector. This study aims to determine the potential implementation impact of the MEP-GAC through an in-depth analysis of the management context, land use scenarios, health criteria values adopted and exposure pathways considered. The MEP-GAC have been proposed for two broad categories of land use scenarios for contaminated land risk assessment, and these two categories of land use scenarios need to be further delved, and a MEP-GAC for Chinese cultivated land scenario ought to be developed, to ensure human health protection of Chinese farmers. The MEP-GAC have adopted 10−6 as the acceptable lifetime cancer risk, given the widespread extent and severe level of land contamination in China, consideration should be given to the decision on excess lifetime cancer risk of 10−5. During risk assessment process in practice, it is better to review the 20% TDI against local circumstances to determine their suitability before adopting it. The MEP-GAC are based on a SOM value of 1%, for regions with particularly high SOM, it might be necessary to develop regional GAC, due to SOM’s significant impact on the GAC developed. An authoritative risk assessment model developed based on HJ25.3-2014 would help facilitate the DQRA process in practice. The MEP-GAC could better reflect the likely exposures of China’s citizens due to vapour inhalation by using characteristics of Chinese exposure scenarios, including China-generic building stock, as inputs into the Johnson and Ettinger model as opposed to adoption of the US EPA parameters. The MEP-GAC once implemented will set the trajectory for the development of the investigation, assessment and remediation of land contamination for years.