these areas contain and support vast and highly productive wildlife resources. 

 Wetlands are particularly sensitive to pollution damage during periods of 

 seed production and spring growth and during waterfowl migration and nesting 

 periods. Substrates are typically muddy or silty and are regularly exposed 

 tidally. 



Except for rare cases, oil enters the marshes through the major drainage 

 channels and later spreads into the less accessible interior areas. Contamination 

 is usually restricted to the outer 1 or 2 m of marsh fringe, unless total 

 submergence of an area is involved. In high current drainage channels, 

 the depth of the zone of contamination may be even less. Restriction of 

 contamination to fringe areas appears to be related to the filtering 

 action of the plants and debris and the quelling of the energy of the 

 driving mechanism. Within these fringe areas, contamination is usually 

 limited to the surface of the substrate and plant stalks, although limited 

 amounts may enter the substrate via worm tubes and burrows. Photosynthetic 

 portions of the plants extending above the high-tide level usually are not 

 oil -contaminated. Plants partially contaminated by residual and low 

 toxicity oils can be expected to recover. When coverage is total or more 

 toxic oils are involved, mortality may occur. 



RESTORATION TECHNIQUES 



Low-pressure flushing provides what is probably the most environmentally 

 acceptable restoration technique. If the flushing is properly conducted, 

 disturbance of the marsh surface is minimal, and the mechanism originally 

 conveying the contamination into the marsh is reversed, floating the bulk 

 of the oil back into the water where it can be recovered. If the flushing 

 is conducted before significant weathering has taken place, even heavy residual 

 oils can be largely removed. Care must be taken not to use excessive pressure, 

 which would cause physical damage to plants, induce erosion, and emulsify 

 the oil. 



Granular sorbents applied directly to the marsh fringe may be useful 

 in the treatment of light oil contamination, provided the application is 

 immediate. By temporarily containing the oil, the sorbents slow toxic reactions 

 with the plants and penetration into the soil, thus buying time for more 

 complete recovery efforts. After an extended period, application of sorbents 

 serves little practical purpose. If sorbents are applied, only degradable 

 types should be used, and provision should be made for their recovery. If 

 care is exercised, granular sorbent recovery is not difficult. These materials 

 are surprisingly easy to remove completely with low-pressure flushing. Freed 

 sorbents float and can thus be collected with booms and recovered by vacuum 

 apparatus or seines. 



If the type of oil and the situation itself permit, burning may be a 

 useful restoration tool. In many parts of the United States, marshlands are 

 burned routinely as a management technique. In the presence of oil, burning 

 may be more intense and longer in duration, but field experience suggests 

 that damage to buried root systems will be insignificant and that recovery 

 will be rapid. Difficulties in the application of burning techniques include 

 the ignition and sustaining of burning on one hand and control of the result- 

 ing fire on the other. Air pollution aspects must also be considered. 



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