SEGH Articles

# Ecosystem services to alleviate micronutrient malnutrition in Sub Saharan Africa

20 May 2011
Ecosystem Services concepts have great potential for linking biogeochemistry, health and policy formulation for poverty alleviation.

Mineral malnutrition due to environmental and cultural factors is widespread in sub-Saharan Africa (SSA).  A multi-national research consortia led by the University of Nottingham (UoN) undertook a pump priming project to explore if Ecosystem Services could provide an effective conceptual framework to link biogeochemical cycles of dietary minerals and poverty.  The project initially focussed on iodine, selenium and zinc in Malawi and Zambia.  Through data integration, feasibility studies, networking and capacity building we addressed three target themes: Biogeochemistry, Nutrition, and Economics.

Biogeochemistry: we developed a new GIS (ArcGIS) framework linking soil and land-use data has been submitted for open-access peer review publication.  New geochemical data for soils and vegetation were incorporated from an aligned project (UoN) and other spatial data (e.g. DFID FarmLime, BGS). Through integration of soil types in GIS, we have found that the population Se intake from maize is typically 6-7 µg Se per day, which represents ~10% of the dietary requirements for Se. Since maize provides the majority of dietary energy to the rural poor of SSA, this study revealed for the first time that chronic Se deficiency is endemic for the majority of the population and is largely influenced by input from soil.

Major knowledge gaps still exist.  Further  sampling, capacity building and data integration activities were therefore planned at a workshop in Lilongwe in September 2010 with multiple government departments and regional academics for future funding application.

Nutrition: a feasibility study was completed to study the spatial variation in I, Se and Zn dietary intake and status  in Malawi as a case study.  The National Health Sciences Research Committee of the Malawi Ministry of health granted ethical approval for dietary and biomarker surveys and intake analyses across several villages.  Importantly, sensitisation visits to the villages and farmers was undertaken by extension services, Ministry of Health and PI's.  Data showing strong geochemical control of intake and status, and these will be submitted for publication later in 2011.

Economics: a novel Ecosystem Services framework was developed based on: modelling soil-to-diet relationship using mineral / dietary-energy units; food choices and land-use; quantifying relationship between disease burdens and poverty at population levels. Economic analyses were formalised using World Health Organisation Disability Adjusted Life Years (DALYS), which incorporated a willingness to pay for intervention.   Such analyses provide a useful policy tool at national and regional scales.

For example: despite limited data, a pilot analysis estimated that 3,955 healthy life years (DALYS) per 1m population per year are lost each year in Malawi due to Zn deficiency alone, mostly due to infant mortality.  This represents an economic loss to Malawi of >1% GDP per year.  Economic analyses for I, Se and other elements requires more data.

This work was funded via the Ecosystem Service Poverty Alleviation programme by UK DFID-NERC.

Project partners included: British Geological Survey, University of East Anglia, Genius Consultancy, University of Sabanci, University of Adelaide, University of Otago, University of Malawi, University of Zambia, Ministry of Agriculture & Health (Malawi).

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

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### Abstract

Phosphate fertilizers were first implicated by Schroeder and Balassa (Science 140(3568):819–820, 1963) for increasing the Cd concentration in cultivated soils and crops. This suggestion has become a part of the accepted paradigm on soil toxicity. Consequently, stringent fertilizer control programs to monitor Cd have been launched. Attempts to link Cd toxicity and fertilizers to chronic diseases, sometimes with good evidence, but mostly on less certain data are frequent. A re-assessment of this “accepted” paradigm is timely, given the larger body of data available today. The data show that both the input and output of Cd per hectare from fertilizers are negligibly small compared to the total amount of Cd/hectare usually present in the soil itself. Calculations based on current agricultural practices are used to show that it will take centuries to double the ambient soil Cd level, even after neglecting leaching and other removal effects. The concern of long-term agriculture should be the depletion of available phosphate fertilizers, rather than the negligible contamination of the soil by trace metals from fertilizer inputs. This conclusion is confirmed by showing that the claimed correlations between fertilizer input and Cd accumulation in crops are not robust. Alternative scenarios that explain the data are presented. Thus, soil acidulation on fertilizer loading and the effect of Mg, Zn and F ions contained in fertilizers are considered using recent $$\hbox {Cd}^{2+}$$ , $$\hbox {Mg}^{2+}$$ and $$\hbox {F}^-$$ ion-association theories. The protective role of ions like Zn, Se, Fe is emphasized, and the question of Cd toxicity in the presence of other ions is considered. These help to clarify difficulties in the standard point of view. This analysis does not modify the accepted views on Cd contamination by airborne delivery, smoking, and industrial activity, or algal blooms caused by phosphates.

• Effects of conversion of mangroves into gei wai ponds on accumulation, speciation and risk of heavy metals in intertidal sediments 2018-06-23

### Abstract

Mangroves are often converted into gei wai ponds for aquaculture, but how such conversion affects the accumulation and behavior of heavy metals in sediments is not clear. The present study aims to quantify the concentration and speciation of heavy metals in sediments in different habitats, including gei wai pond, mangrove marsh dominated by Avicennia marina and bare mudflat, in a mangrove nature reserve in South China. The results showed that gei wai pond acidified the sediment and reduced its electronic conductivity and total organic carbon (TOC) when compared to A. marina marsh and mudflat. The concentrations of Cd, Cu, Zn and Pb at all sediment depths in gei wai pond were lower than the other habitats, indicating gei wai pond reduced the fertility and the ability to retain heavy metals in sediment. Gei wai pond sediment also had a lower heavy metal pollution problem according to multiple evaluation methods, including potential ecological risk coefficient, potential ecological risk index, geo-accumulation index, mean PEL quotients, pollution load index, mean ERM quotients and total toxic unit. Heavy metal speciation analysis showed that gei wai pond increased the transfer of the immobilized fraction of Cd and Cr to the mobilized one. According to the acid-volatile sulfide (AVS) and simultaneously extracted metals (SEM) analysis, the conversion of mangroves into gei wai pond reduced values of ([SEM] − [AVS])/f oc , and the role of TOC in alleviating heavy metal toxicity in sediment. This study demonstrated the conversion of mangrove marsh into gei wai pond not only reduced the ecological purification capacity on heavy metal contamination, but also enhanced the transfer of heavy metals from gei wai pond sediment to nearby habitats.

• Cytotoxicity induced by the mixture components of nickel and poly aromatic hydrocarbons 2018-06-22

### Abstract

Although particulate matter (PM) is composed of various chemicals, investigations regarding the toxicity that results from mixing the substances in PM are insufficient. In this study, the effects of low levels of three PAHs (benz[a]anthracene, benzo[a]pyrene, and dibenz[a,h]anthracene) on Ni toxicity were investigated to assess the combined effect of Ni–PAHs on the environment. We compared the difference in cell mortality and total glutathione (tGSH) reduction between single Ni and Ni–PAHs co-exposure using A549 (human alveolar carcinoma). In addition, we measured the change in Ni solubility in chloroform that was triggered by PAHs to confirm the existence of cation–π interactions between Ni and PAHs. In the single Ni exposure, the dose–response curve of cell mortality and tGSH reduction were very similar, indicating that cell death was mediated by the oxidative stress. However, 10 μM PAHs induced a depleted tGSH reduction compared to single Ni without a change in cell mortality. The solubility of Ni in chloroform was greatly enhanced by the addition of benz[a]anthracene, which demonstrates the cation–π interactions between Ni and PAHs. Ni–PAH complexes can change the toxicity mechanisms of Ni from oxidative stress to others due to the reduction of Ni2+ bioavailability and the accumulation of Ni–PAH complexes on cell membranes. The abundant PAHs contained in PM have strong potential to interact with metals, which can affect the toxicity of the metal. Therefore, the mixture toxicity and interactions between diverse metals and PAHs in PM should be investigated in the future.