CO 

 CO 



g Deevey (1970) puts it: 



5 What follows, if R.NHj.SH is to remain a renewable resource, is that water, mud, 



f— air, and land are closely linked by oxidation-reduction cycles in which reduction is 



W performed entirely by organisms. 



Q Pollution Filtration 



< One of the most significant roles of wetlands is their ability to 



Z remove pollutants. Preliminary studies in the Tinicum Marshes indicate 



that this area receives sewage from three treatment plants and that a 



significant reduction in absolute amounts of pollution occurs by the 



time the water has passed through the 512 acres of marsh. Grant and 



Patrick ( 1970) succinctly summarize this vital role as follows: 



It is significant that reductions in BOD, P-PO.,, N-NH :t , and N-NO :i , did occur in the 

 excursion of the river water over the marshland in the time interval of 2 to 5 hours. 

 This reduction occurred in 57% of the BOD measurements, 57% of the P-P0 4 

 analyses, 66% of the N-NH :I , and 63% of the N-NO : , analyses. Oxygen increases oc- 

 curred in 73% of the analyses. It is difficult to determine from the information at 

 hand why the decreases in pollution load were not always consistent but are probably 

 due to irregular pattern of flow and the variability of pollution load. If we take the ap- 

 proximate average value for each of these characteristics this would mean an approxi- 

 mate reduction of P-PO., of 190 mg/ft :1 of water per day; BOD of 310 mg/ff' 1 per day; 

 N-NH : , of 176 mg/ft :t per day; N-NO :) of 3.2 mg/ft :i per day and an increase of oxygen 

 of 4 1 2 mg/ft :1 per day. Since the wet area of the marsh is about 5 1 2 acres, this would 

 amount to a reduction per day of approximately 7.7 tons of BOD, 4.9 tons P-PO.,. 4.3 

 tons N-NH :1 , 138 lb. N-NO,,, and an increase of 20 tons of oxygen. From these 

 preliminary results it is evident that the marshlands play an important role in reducing 

 the nutrient load in water and in increasing the oxygen content. 



In Georgia, water quality was studied along the Flint and Alcovy 

 rivers to assess the value of river bottomland swamps in pollution 

 reduction. In the Flint River system, the Georgia Water Quality Con- 

 trol Board reports a high degree of recovery by a very organically pol- 

 luted stream within a distance of 6 miles, where there were extensive 

 swamps. It was also observed that the degree of recovery was directly 

 correlated with the presence of the adjacent swamps. Along Mountain 

 Creek, a tributary of the Alcovy River, the Federal Water Pollution 

 Control Administration found extreme pollution due to human sewage 

 and chicken offal (Wharton 1970). However, after passing through 

 2.75 miles of swamp forest along the Alcovy, the river water was 

 designated as clean; and water quality was excellent after traversing an 

 additional 7 miles of swamp. Data also suggest that coliform counts, 

 dissolved oxygen, and biological oxygen determination (BOD) all 

 returned to more favorable levels downstream from the swampy areas. 

 In another study of oil wastes on the Gothard's Branch in Douglas 

 County, Georgia, Turner and Ahearn (1970:18) found that the largest 

 amount of the degradation of the pollutant occurs along the swampy 

 portion of the stream. 



The role of swamps in sediment removal has also been documented. 

 Wharton (1970) estimates that the value of the Alcovy River Swamp 

 as a sediment accretor exceeds $3000 annually. This function would 

 be destroyed by channelization, a potential threat to such wetlands. It 



