WHAT DOES IT ALL MEAN? 



A general picture has been presented as to how chloride in New Hampshire 

 has increased from more or less natural concentrations to present levels. On a 

 statewide basis, the increase in discharge has been about seven fold, and the 

 increase in storage has been at least two fold. The importance of road deicing 

 salt is obvious. However, nothing in the general picture seems to indicate any 

 severe problems with chloride. Nevertheless, as suggested by Figures 3 through 9, 

 problems have arisen and can be expected to continue. Therefore, the general 

 picture needs to be modified by taking a closer look at certain aspects. 



One important feature is that the chloride increase has come mainly in the 

 more urbanized areas and along highways, whereas mountainous areas above 

 highways have been little effected. Attention should be centered on more 

 localized areas and to the indirect effects as alluded to in the introduction. These 

 are discussed briefly by major topic rather than in a detailed fashion. Emphasis is 

 placed on material not adequately covered in the literature. 



VEGETATION AND SOILS 



The effect of road deicing salt on vegetation and soils was seen fairly early in 

 New England^*^'^^ and elsewhere. ^8 Vegetation with low salt tolerance such as 

 various species of maples, elms, and grasses are killed or seriously impaired within 

 about 30 feet of salted highways. Sodium is the major source of trouble although 

 chloride may be at higher concentrations. The killing or damaging of vegetation not 

 only has aesthetic implications, but practical ones as well because vegetation serves 

 to control erosion and shrubbery and trees muffle traffic sounds. 



Sodium affects soils by causing an alteration to a less desirable structure. The 

 sodium from road deicing salt or othe.- source of chloride, replaces or exchanges 

 for calcium and magnesium, thereby impairing fertility and permeability.^^ An 

 interesting side effect is that ground and surface waters may show more increase 

 in calcium and magnesium than in sodium. Chloride is not likely to replace other 

 anions in soils, but it may become delayed in transit due to the depletion of soil 

 moisture above the water table.'^^ This chloride will be flushed downward when 

 adequate soil water moves through the soil. 



'"Lacasse & Rich, Maple Decline in New Hampshire, 54 Phytopathology 1071-1075 

 (1964). 



Hutchinson, Environmental Pollution from Highway Deicing Compounds, 25 J. Soil and 

 Water Conservation 144-146 (1970). 



^^STRUZESKI 85-96. 



39 Id, 86 



Toler & Pollack, Retention of chloride in the unsaturated zone, 2 J. Research U.S. 

 Geological Survey 119-123 (1974). 



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