| Popis: |
The sediment composition of eight lakes in the Netherlands has been investigated to estimate the release of phosphate (P) from sediments. The amount of phosphate available to algae from sediments has been assessed by means of bioassays, using derivative spectroscopy to measure algal growth. The average total P concentration of the top 5-cm sediment layer varied from 1.1–5.7 mg g-1 dw. Based on the bioassays, available P varied between 10–45% of total P. The uptake by algae increased strongly with rising pH. Among the P-binding components in the sediment (Fe, CaCO3, clay, and organic matter), only organic matter was strongly negatively correlated with the available P, indicating that a high organic matter content tends to diminish the availability of the sediment P. |
