Exchange of Inorganic Phosphate between River Waters and Bed-Sediments
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- 作者：William A. House and Frank H. Denison
- 刊名：Environmental Science & Technology
- 出版年：2002
- 出版时间：October 15, 2002
- 年：2002
- 卷：36
- 期：20
- 页码：4295 - 4301
- 全文大小：137K
- 年卷期：v.36,no.20(October 15, 2002)
- ISSN：1520-5851
文摘
The kinetics of the release of Soluble Reactive Phosphorus(SRP) in oxic and anoxic conditions and uptake in oxicconditions by contaminated river sediments (River Blackwaterin Southern England) were measured using a fluvariumchannel operated to mimic environmental conditions. Releaserates (from 1 to 10 nmol m-2 s-1) and uptake rates weremodeled successfully using a Parabolic equation and DiffuseBoundary Layer model. A SRP release experiment over61 days showed that large gradients in SRP developed inthe porewater as a result of diffusion, sorption, and in-situ generation of SRP in the anoxic zone. This was modeledusing a new Triple Zone Model that incorporated diffusionthrough a liquid boundary layer and sorption/desorptionin oxic and anoxic zones. The results highlighted theimportance of the oxic zone in controlling the exchangeof SRP between the sediment and water column. The modelwas also applied to explain why the Equilibrium PhosphateConcentration (EPC0) of the sediment measured in oxicconditions was constant (and equal to the value calculatedfrom sorption isotherm measurements) during 2-dayrelease experiments, and also why it increased in theuptake experiments. Measurements in anoxic conditionsshowed the importance of the sediment temperaturein controlling the flux at the interface.