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Release of organic and inorganic matter from flooded soils in hydroelectric reservoirs

Abstract:

The objective of this research was the determination of water level fluctuations (drawdown) effect on releases of organic carbon, phosphorus and nitrogen from flooded soils in response to conditions existing under simulated drawdown occurring in hydroelectric reservoirs. Two types of soil were considered: forest soil humus or potzol (Pleurozium sp) and the moss (Sphagnum moss). Separate series of experiments were done considering partial drying, freezing and thawing of the soil samples between submergence cycles. Two series of experiments were done at ambient temperature under distinct pH conditions during periods of 165 and 225 days respectively. Results were compared with soil samples having been continuously submerged. Depending upon the type of treatment suffered by the soil samples, releases of soluble matter in the early submergence cycles increased by a factor of 2 to 10 with respect to the amount of soluble matter released by soil samples not having been exposed to any treatment between submergence cycles.