Abstract
ABSTRACT A controlled oil spill experiment to determine natural recovery rates and the efficacy of potential remediation strategies in wetland ecosystems was initiated in June 1999 at a site on the St. Lawrence River, Canada dominated by Scirpus pungens. A weathered light crude oil (Mesa) was applied on 16 plots (5 m × 4 m) at the rate of 12 L per plot. Treatment of the plots included: natural attenuation (no treatment), nutrient amendment with granular ammonium nitrate and super triple phosphate, a similar treatment with plants continuously cut back (to evaluate the influence of plant growth on remediation), and a nutrient amendment treatment with sodium nitrate instead of ammonium nitrate. To elucidate the effect of nutrient amendments alone, four unoiled plots were fertilized with ammonium nitrate and triple super phosphate. Sediment samples were routinely recovered for chemical and toxicological analysis over a 21-week period that effectively covered the natural growth season of the plants. Significant changes in biological measures of habitat were observed. S. pungens, the dominant plant species, was tolerant to the oil, and its growth was significantly enhanced above that of the unoiled control by the addition of nutrients. Other biotest organisms (bacteria, Vibrio sp.,; invertebrates, Daphnia, Hyalella, and Viviparus sp.) provided additional evidence of both enhanced recovery and potential detrimental effects. GC-MS analysis could not resolve significant changes in the composition of the residual oil as a result of experimental treatments. This discrepancy in the detection of treatment efficacy between the chemical and biological methods may be due to induced tolerance to the contaminant hydrocarbons, changes in the bioavailability of the residual oil associated with stimulated plant growth, and detrimental effects of the type and quantity of bioremediation agents used.
Published Version
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call