Wetlands are capable of reducing sulfate to sulfide. Sulfate may exist in soils or may enter wetlands through tidal flow or atmospheric deposition. Suspended solids Wetlands filter suspended solids from water that comes into contact with wetland vegetation. All soils contain at least a low concentration of metals but in some locations human activities have resulted in metal levels high enough to cause health or ecological risks in water resources. Metals may exist in wetland soils or enter wetlands through surface or ground water flow.
Iron hydroxides are particularly important in retaining meta ls in salt marshes.
Wetlands remove more metals from slow flowing water since there is more time for chemical processes to occur before the water moves out of the wetland. Burial in the wetland substrate will keep bound metals immobilized. Immense varieties of species of microbes, plants, insects, amphibians, reptiles, birds, fish, and other wildlife depend in some way on wetlands. Wetland plants play an integral role in the ecology of the watershed. Wet land plants also reduce erosion as their roots hold the streambank, shoreline, or coastline.