The importance of sediment phosphorus release in the restoration of very shallow lakes (The Norfolk Broads, England) and implications for biomanipulation

The release of phosphorus from the sediment of 6 Norfolk Broads is reviewed. Chemical mechanisms controlling the process were examined by comparing measured phosphorus release rates with total sediment iron to phosphorus and interstitial iron(II) to phosphorus ratios. High phosphorus release rates (up to 278 mg per m2.d) were associated with high total sediment iron:phosphorus ratios and occurred when sulphide from sulphate reduction removed iron(II) from the pore water. The effects of fish removal on benthic chironomid density, the pore water profiles of dissolved phosphorus, iron and sulphide, and the rate of phosphorus release from the sediment are discussed. There are 41 references.