Predicting the environmental fate and mobility of chemical elements in soils and waters is a necessary component of risk assessment. It is known that the interaction depends upon factors such as pH and the chemically reactive surfaces associated with mineral and organic matter. Moreover these interactions are competitive and non linear and in addition many reactive particles are heterogeneous. Therefore in our work we use geochemical models that can make predictions based on inputs such as pH, soil organic matter content and mineralogy.

For example from our understanding of soil chemical processes we have developed a mechanistic model that predicts the partitioning of metals between the soil solid and solution phases. This “soil model” describes metal binding to three distinct solid phases, which are soil organic matter, Fe/Al hydroxides and clay (fixed charge phyllosilicate). Parameters to quantify the amounts of these phases in Scottish soil are currently being obtained for the new National Soil Inventory Scotland (NSIS) database

Our research in this area focuses on developing models to:

• Determine metal solubility in sewage sludge treated soils
• Quantify retention of phosphate in iron ochre filters
• Predict dissolved organic matter solubility and leaching
• Assess trace element sources and availability in post petroleum agriculture

Who is working in this area?

• Marc Stutter
• David Lumsdon
• Jeff Bacon