Dynamic Evaluation of Intertidal Wetland Sediment Quality in a Bay System

Intertidal wetlands are fragile ecological systems vulnerable to changing environmental conditions. Using the Rapid Assessment Approach, intertidal wetland sediments were dynamically evaluated in the Deep Bay, South China in terms of monitored benthic macroinvertebrates. The observation and expectation ratio indicated variations of intertidal wetland sediment quality had taken place at certain ecologically sensitive areas, such as the Mai Po Marshes. Series of dynamic models were used to simulate the behavior of certain environmental variables (i.e. cadmium, copper, lead and zinc accumulation rates) that might have adverse effect on the growth of benthic macroinvertebrates, and hence interpreted the results of the ecological assessment. The changes of sediment quality were primarily due to anthropogenic activities and were further attributed largely to the industrial discharged heavy metals which were unevenly distributed and heavily accumulated at some sensitivity areas (i.e. Futian National Natural Reserve and Mai Po Marshes) with help of sediment deposition altered by long-term tidal flow actions in Deep Bay.