Suspended particulate matter and turbidity

Suspended Particulate Matter (SPM) carries pollutants, shades light and so inhibits primary production, and embodies particulate organic matter forming part of the marine ecosystem. It is highly variable according to depth and physical processes in the area (i.e. tide and current regimes and wind). Traditional assessment methodologies are still used successfully, but various optical techniques are increasingly being used, for particle size as well as weight of SPM. This has increased understanding of the dynamics and processes associated with SPM in shelf seas, especially tidal stirring of sediments. Remote sensing measurements of ocean colour provide time series for studying variability of suspended material, phytoplankton pigments and coloured dissolved material. Trends in SPM concentrations and therefore turbidity for UK waters show no significant change over the last five years. Remote sensing measurements are still hampered by weather (especially cloud) and by a lack of understanding of optics in (turbid) coastal and shelf waters. For improved shoreline management plans there is a need for more quantitative information, especially on shoreline processes, wave interactions (inshore wave climate) and water flow along coasts. There is much interest for Integrated Coastal Zone Management.