Programme Leader: Professor Steve McGrath
The programme aims to understand the source, behaviour, fate and impact of pollutants in soil and in the food chain in order to protect against environmental damage, and also to devise methods for remedial treatment.
Both inorganic and organic pollutants threaten soil fertility and sustainability of agroecosystems. Metals accumulate in topsoil and poison crops, food, and important soil microbial groups. There is also concern about organic compounds, as many can be carcinogenic or oestrogenic. Some of these are added to soil purposely, as in the case of crop protection chemicals, but others enter soils inadvertently as contaminants in fertilizers and wastes or via atmospheric deposition. In the UK, 10 million tonnes of sewage sludge and 50 million tonnes per year of domestic waste are added to land as well as paper waste, food processing wastes, sediments, and other industrial wastes.
|Factory manufacturing compost from domestic refuse|
It is Government policy to increase the recycling of organic wastes such as sewage sludge, along with other wastes that can no longer be dumped in rivers or seas, due to EU and other international agreements. Such recycling must be done in a safe way, and scientific information is needed to prevent pollution and guide environmental policies. Basic and applied scientific knowledge is required on pollution due to heavy metals and organic compounds, as well as an understanding of the factors determining soil quality in order to protect soils and waters from future degradation.
|Experiments with sewage sludge at our experimental farm|
It is estimated that there are 100,000 sites in the UK, and approximately 1,400,000 in the EU, that are contaminated. These need either clean-up or risk reduction techniques in order that they can be either re-utilised, or simply to ameliorate the pollution. Estimated UK clean-up costs for remediating contaminated land are £9-20B and it is clear that individuals, local authorities and even large multinational companies cannot afford expensive clean-up techniques. Therefore, low-cost technologies including enhancing bioremediation in the rhizosphere (David Johnson) and fixation of pollutants with co-products (Steve McGrath) are urgently needed. Phytoremediation is an emerging technology. Fundamental studies are only now being made of the uptake, storage and recycling of metal hyperaccumulator plants (Fangjie Zhao).
Phytoextraction of toxic metals using hyperaccumulating plants
Zinc is preferentially sequestered in the epidermal cells of the leaves of Thlaspi caerulescens
Protection of soil and food quality
This programme addresses requirements for development of bioremediation of contaminated land and water, environmental sensors and processes for uptake of metals and degradation of chemicals. The aims are to protect against damage to soil health and the food chain, whilst contributing to the development of sustainable systems for waste disposal, and protecting and enhancing the rural environment by reducing pollution, protecting the public by reducing water pollution and contamination. For example, cadmium and lead are contaminants of concern in the food chain, and our projects aim to establish the extent to which these metals are taken up by wheat and barley. More importantly, we also seek to know how this is affected by soil loadings of these metals and other soil and crop genotypic properties that determine their bioavailability.
|The distribution of Cd and Pb in British cereals - the proposed EU limits are marked (red for Cd, blue for Pb). Most of the data are in the 'boxes', showing that nearly all samples are below the limits.|
Policy and legislation
Our research also provides input to legislation at the national and EU level, for example on sewage sludge (Amar Chaudri), pesticide use and contaminants in food (Steve McGrath, Richard Bromilow). A major contribution is also being made to the development of a National Soil Protection Policy and the design of a National Soil Monitoring Network (Steve McGrath). Various interactions take place with other countries and with international agencies such as FAO/IAEA, UNIDO and UNECE.
|Cadmium concentration in the topsoils of England and Wales (values in mg/kg soil)|
This programme also includes work aiming to avoid inappropriate use of pesticides. Their transport into waters and uptake by plants as well as pesticide persistence in soil and movement to water are studied, and related to the physicochemical properties of pesticides, soil type, application technique and climatic factors. This knowledge is incorporated into expert systems and models that assist in making decisions on pesticide registration both by DEFRA PSD in the UK, and also abroad (Richard Bromilow).
Rothamsted Lime Requirement Model (RothLime) (New: October 2002)
Projects are sponsored by BBSRC, DEFRA Environmental Protection Division, EU, the Environment Agency, National Assembly of Wales, Home Grown Cereals Authority, the DEFRA Pesticide Safety Division, UK Water Industries Research Ltd., International Lead Zinc Research Organisation and other industries.
|Argon plasma at 6000oC used to analyse elements in soil, plant and liquid samples|
|Degraded land contaminated with arsenic|
Soil Protection and Bioremediation Group Publications
Soil Protection and Remediation Websites: