SEGH Articles

Soil: an important part of a healthy diet?

20 May 2011
Iodine is essential for healthy human life, and is taken up by crops from the soil. However, current research shows that the soil itself has an important part to play in determining how much iodine reaches our food.

Iodine is essential for healthy human life, and insufficient intake can result in reduced mental and physical well-being. In some places, however, even when there is plenty of iodine present in soil, there is still a deficiency in food, crops and grazing pasture for livestock, with social and economic impacts for affected communities.

Cows rely on sufficient iodine intake from the pasture they graze, but in some areas require dietary supplements to maintain health.

A current Nottingham-based PhD project is focussing on how the interaction between soil and iodine affects the availability of iodine to plants, and hence how the soil influences the amount of iodine entering the food chain. Research is being carried out using soils from Northern Ireland, mainly from pasture sites, to investigate how iodine, washed into soil by rain, behaves when it comes into contact with the earth: is it leached through the topsoil layer to depths inaccessible to roots? Is it locked away onto solid soil particles? Does it stay within the soil moisture, to potentially be taken up by plants? Current understanding is that all of these scenarios occur to some extent, and the properties of the individual soil determine ultimately how much iodine is taken up by the plants growing on it.

Soils have a range of properties including texture and composition which affect how iodine behaves once it is in contact with them.

A map of total soil iodine concentrations in Northern Ireland has recently been produced by the Geological Survey of Northern Ireland as part of the Tellus project (Smyth, D. and C. C. Johnson (2011). "Distribution of iodine in soils of Northern Ireland." Geochemistry-Exploration Environment Analysis 11(1): 25-39). Interpretation of the map revealed that although iodine concentrations in surface soils of Northern Ireland are generally high (on average around 10 mg kg-1), the concentration range was large (0.5 - 600 mg kg-1) and depended strongly on the characteristics of the soil. Soils rich in organic matter (e.g. peat) tended to retain most iodine. Additionally, a coastal fringe of particularly high iodine concentrations was identified and linked to relatively high marine concentrations of iodine. Within the last decade the British Geological Survey (BGS) has investigated the concentration of iodine in soils around the world, including in China, Morocco and Argentina. These projects have confirmed that low soil iodine concentration can result in whole communities being affected by iodine deficiency diseases, but have also shown that iodine deficiency can be a problem in areas where soil iodine concentration is not particularly low.  

 

This PhD research, jointly sponsored by the University of Nottingham and the BGS University Funding Initiative, builds on existing knowledge of iodine concentration in soils of Northern Ireland and looks deeper into how soil itself can affect the availability of iodine and why the problem does not occur everywhere. The ultimate aim is to create a computer model to predict where iodine deficiency diseases are likely to occur, allowing intervention measures to be planned for the places where they are most needed.

 

Soil and grass samples were collected in Northern Ireland...

 

 

 

 

...where careful recording of soil properties including colour and texture was required.

 

 

For further information about this project, please email Hannah Smith on plxhes@nottingham.ac.uk.

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

  • Agro-ecological suitability assessment of Chinese Medicinal Yam under future climate change 2019-10-15

    Abstract

    Chinese Medicinal Yam (CMY) has been prescribed as medicinal food for thousand years in China by Traditional Chinese Medicine (TCM) practitioners. Its medical benefits include nourishing the stomach and spleen to improve digestion, replenishing lung and kidney, etc., according to the TCM literature. As living standard rises and public health awareness improves in recent years, the potential medicinal benefits of CMY have attracted increasing attention in China. It has been found that the observed climate change in last several decades, together with the change in economic structure, has driven significant shift in the pattern of the traditional CMY planting areas. To identify suitable planting area for CMY in the near future is critical for ensuring the quality and supply quantity of CMY, guiding the layout of CMY industry, and safeguarding the sustainable development of CMY resources for public health. In this study, we first collect 30-year records of CMY varieties and their corresponding phenology and agro-meteorological observations. We then consolidate these data and use them to enrich and update the eco-physiological parameters of CMY in the agro-ecological zone (AEZ) model. The updated CMY varieties and AEZ model are validated using the historical planting area and production under observed climate conditions. After the successful validation, we use the updated AEZ model to simulate the potential yield of CMY and identify the suitable planting regions under future climate projections in China. This study shows that regions with high ecological similarity to the genuine and core producing areas of CMY mainly distribute in eastern Henan, southeastern Hebei, and western Shandong. The climate suitability of these areas will be improved due to global warming in the next 50 years, and therefore, they will continue to be the most suitable CMY planting regions.

  • Application of stable isotopes and dissolved ions for monitoring landfill leachate contamination 2019-10-15

    Abstract

    We evaluated groundwater contamination by landfill leachate at a municipal landfill and characterized isotopic and hydrogeochemical evidence of the degradation and natural attenuation of buried organic matter at the study site. Dissolved ion content was generally much higher in the leachate than in the surrounding groundwater. The leachate was characterized by highly elevated bicarbonate and ammonium levels and a lack of nitrate and sulfate, indicating generation under anoxic conditions. Leachate δD and δ13CDIC values were much higher than those of the surrounding groundwater; some groundwater samples near the landfill showed a significant contamination by the leachate plume. Hydrochemical characteristics of the groundwater suggest that aquifer geology in the study area plays a key role in controlling the natural attenuation of leachate plumes in this oxygen-limited environment.

  • Lead transfer into the vegetation layer growing naturally in a Pb-contaminated site 2019-10-10

    Abstract

    The lead was one of the main elements in the glazes used to colour ceramic tiles. Due to its presence, ceramic sludge has been a source of environmental pollution since this dangerous waste has been often spread into the soil without any measures of pollution control. These contaminated sites are often located close to industrial sites in the peri-urban areas, thus representing a considerable hazard to the human and ecosystem health. In this study, we investigated the lead transfer into the vegetation layer (Phragmites australis, Salix alba and Sambucus nigra) growing naturally along a Pb-contaminated ditch bank. The analysis showed a different lead accumulation among the species and their plant tissues. Salix trees were not affected by the Pb contamination, possibly because their roots mainly develop below the contaminated deposit. Differently, Sambucus accumulated high concentrations of lead in all plant tissues and fruits, representing a potential source of biomagnification. Phragmites accumulated large amounts of lead in the rhizomes and, considering its homogeneous distribution on the site, was used to map the contamination. Analysing the Pb concentration within plant tissues, we got at the same time information about the spread, the history of the contamination and the relative risks. Finally, we discussed the role of natural recolonizing plants for the soil pollution mitigation and their capacity on decreasing soil erosion and water run-off.