Environmental Feasibility of Using Wetlands to Treat Runoff Pollution

Chemical and ecological characteristics of wetland types commonly occurring in and around Navy bases are reviewed. The natural wetland processes are examined from the perspective of their capacity to remediate nonpoint source pollution NPSP. The ecological habitat value of wetlands is iterated, as are the habitat value changes resulting from pollution loading. Five generic pollutant categories of NPSP are discussed biochemical oxygen demand BOD, nutrients, suspended particulates, heavy metals, and organics petroleum, solvents, biocides. The ecological consequences of each pollutant category, the treatment principles for this pollutant category, and how wetlands can provide the necessary treatment conditions are discussed. Choice of the correct wetland morphology is important for effective NPSP remediation. Guidelines for choosing an existing marsh or construction of a new marsh are provided. A tidal salt marsh construction proposal is reviewed to determine the ecological validity, the expected remediation effectiveness, the side effects, and the legal requirements for the construction. The state of the science is still too immature to confidently predict the effectiveness of the marsh at this site. The indications are that insufficient residence time of the water pollutants will minimize the effectiveness. Also the varied and dynamic exchanges between the marsh and the adjacent water body will hamper efforts to quantitatively determine the level of remediation. sdw