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Prevention of sulphide accumulation and phosphate mobilization by the addition of iron(II) chloride to a reduced sediment: an enclosure experiment
- SMOLDERS, A.J.P., NIJBOER, R.C., ROELOFS, J.G.M.
- Freshwater biology 1995 v.34 no.3 pp. 559-568
- Potamogeton, algal blooms, chlorides, iron, phosphates, planting, sediments, seepage, sulfates, sulfides, summer, surface water, temperature, toxicity, turbidity
- 1. In an enclosure experiment carried out in a ditch receiving sulphate‐enriched seepage water, iron(II) chloride was added to the sediment. In the sediment pore water of the iron‐treated enclosures sulphide levels decreased to very low values (<1 μmol 1−1) immediately after the iron addition while in the control enclosures sulphide reached values up to 500 μmoll−1. 2. The sulphide levels in the sediment pore water were also strongly correlated with temperature. In summer, phosphate mobilization was observed in the non‐treated enclosures while in the iron‐treated enclosures phosphate levels remained low. 3. Total phosphate levels increased greatly in the water layer of the non‐treated enclosures, coincident with an algal bloom and increased turbidity. It is suggested that phosphate mobilization in summer is caused by the reduction of iron(III) phosphate complexes and in this high sulphate water body probably also by the reduction of iron(III) by sulphide and the consequential precipitation of iron(II) sulphide. 4. Iron addition appeared to prevent sulphide toxicity in Potamogeton acutifolius Link which was planted in the enclosures immediately after iron(II) addition. In the non‐iron‐treated enclosures P. acutifolius plants decayed within a few weeks probably as a result of sulphide toxicity.