Dr Mark Hodson, University of Reading
Earthworm populations are helping scientists to understand more about soil that is contaminated with metal, how metals can drive evolution and what effect they themselves have on potentially toxic elements in the earth. Dr Mark Hodson has been using Diamond to study earthworm tissue, excreted soil, and earthworm burrow walls as never before.
One of the key questions being asked is why is it that some populations of earthworms can inhabit contaminated soil and other populations, of the same earthworm species, can’t? It appears that metal tolerant populations of earthworms are evolving and Mark and his colleagues are studying this by seeing if the toxic elements are stored in the earthworm population using different mechanisms. Super metal munching earthworms might have a role to play in soil clean up operations, helping the soil to live again, and our understanding of their evolution is important if we are to successfully tap into this potential.
Dr Paul Schofield, Natural History Museum, London
Metals may be present in soils from a variety of sources such as former mining and industrial sites and can represent a potential hazard to humans and the environment if they are readily released into soil solution or are otherwise available to biological processes. At the moment, methods of treating metal-contaminated soils essentially isolate the soil from the ecosystem by capping or removal of the soil and dumping it elsewhere. These methods are expensive and unsustainable so we need alternative solutions, new ways of reducing contamination without removing the soil.
It now looks likely that one solution will come with the help of a phosphate source, such as bonemeal, which has the ability to immobilize metals. Debate is currently ongoing as to whether bonemeal provides the optimum phosphate source. Obviously the choice of remediation medium is a critical step to the development of this new technology, so we are using Diamond to work towards experimental results on bonemeal treated metal-contaminated soils that either confirm or refute the existence of metal phosphate interactions.
Dr Sam Shaw, University of Leeds
Green rust has the potential to immobilise toxic and radioactive species in contaminated land (e.g. radioactive waste repositories), including uranium, chromium, selenium and zinc. Here in the UK, we are pioneering studies at Diamond that we hope will harness its capabilities as a remediation technology.
The problem with green rust is that it only forms when the level of oxygen is very low. This has prevented researchers from finding out exactly how and under what conditions it forms. To overcome these problems we have recreated the conditions conducive to green rust formation within a contaminated land site on the beamline at Diamond. Using a complex chemical reaction cell, and with the unique power and intensity of the X-ray beam, we have been able to gain a unique insight in to the atomic scale formation and crystallisation of green rust under conditions close to which it forms in contaminated land environments. This work will provide valuable information to predict how and where green rust will form and what effect it will have on the behaviour and migration of pollutants within soil and groundwater.
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