They are also highly dynamic zones, where the mixing of marine and fresh waters results in many chemical changes taking place. Electrochemical and flow injection metal monitors are used in the field to obtain high resolution data for investigations into the behaviours of different metals as they are transported through the estuary. The metal monitors can also determine different metal species dissolved in the water, which leads to greater insight into the chemical transformations taking place. The metal monitors have also been used to follow the metal plumes from the estuaries out into the surrounding coastal waters, allowing a better assessment of the potential impact of the waters to be made. Particle-Water interactions and modelling Many contaminants are very quickly asdorbed onto particles in estuaries.
Particles ultimately sink to the sediment.
Consequently it is important to investigate sediment transport if estuarine processes are to be fully understood, particularly in estuaries which are strongly influenced by tides. Controlled laboratory experiments are also undertaken in order to investigate the interactions between metals in the dissolved and particulate phases. Minute quantities of metal tracers are added to samples of estuarine water, and the concentration of the tracer in the dissolved and particulate phase monitored, in order to assess the extent and rate of partitioning of the metal. Current work is focusing on the Mersey Estuary under the NERC Environmental Diagnostics Programme, which has a long history of contamination. The group has worked extensively in the North Sea and is currently studying the impact of produced waters from North Sea oil platforms on water quality.