DEPLOYMENT OF A THRESHOLD ACTIVATED PUMP SAMPLER IN AN INDUSTRIAL SHOCK LOAD IMPACT STUDY

Shock loading of toxic substances into natural waterways is a pervasiv e practice which has substantial impacts on their biota. This paper de scribes the effects of shock (pulse) pollution loading from two major industries on a river and wetland system in southern Ontario, Canada. The assessment of shock loading frequency indicated that sporadic disc harges of polluted water occurred on average once every other day duri ng the 38 days of monitoring in the period April, 1986 to November, 19 87. To estimate the frequency and intensity of the shock loads, an aut omatic pump sampler that was activated by a threshold conductivity was constructed and deployed. Samples were withdrawn from the river when the specific conductivity of the stream exceeded a threshold value of two times background. Background specific conductivity ranged between 200-250 mu S cm(-1). The impact of these shock load discharges on a do wnstream aquatic plant community in a Class One (Provincially Signific ant) wetland was examined. The area of Thompson's Creek upstream of th e Cyanamid Chemical Company displayed a normal complement of aquatic o rganisms while downstream of the company's main discharges for a dista nce of nearly 2 km, the stream was barren of nearly all aquatic life. A reef-like structure in which nickel, chromium, and lead reached resp ectively 2900, 2100 and 2210 mg kg(-1) dry weight of sediment was loca ted in the Welland River near the outfall of the Atlas-Mansfield storm sewer adjacent to the Atlas Specialty Steels Company. The average how rate at the outfall of the Atlas-Mansfield storm sewer into the Wella nd River was approximately 28 400 m(3) day(-1) in 1986 (MOE 1987). A s mall area referred to as the Atlas reef because of the high iron conce ntrations giving the sediments a cement-like condition, was devoid of all higher aquatic plants.