Effects of power line construction upon the carbonate water chemistry of part of a mid-latitude swamp

Beverly Swamp in southern Ontario is typical of a wetland in carbonate terrain. At two sites in the swamp, a study was conducted between 1975 and 1977 to determine the impact of a power-line construction programme upon the carbonate water chemistry of the perched ground water. Construction activities included deforestation along a narrow corridor across the swamp as well as drilling, pumping and grouting during the erection of towers. The latter resulted in (1) contamination of the perched ground water by the alkaline water forced to the surface from near the dolomite bedrock, and (2) disturbance of the peat and marl structure. These in turn induced higher pH, total hardness and bicarbonate concentrations in the perched ground water. Although such effects persisted beyond the construction period, the spatial patterns exhibited by the pertinent hydrochemical variables indicate that the impacts were spatially confined. It is inferred that recurrent flooding will enhance recovery of the disturbed sites.