摘要：Sequestration of phosphorus in sediments is critical in controlling the availability of phos- phate for algal growth in shallow bays of the Gulf of Finland (Baltic Sea). In the organic- rich, low-salinity-water bay studied, the release of phosphorus from the sediments was sensitive to bioirrigation and oxygen conditions in the water. This was explained by the importance of hydrated iron oxides in binding phosphorus at the sediment surface, the sen- sitivity of iron-bound phosphorus to redox conditions, and the presence of soluble iron and sulphate. Chemical forms of phosphorus, especially phosphorus bound by redox-sensitive hydrated iron oxides, are regulated by the amount of degradable organic matter, availabil-ity of oxygen, iron and sulphate as well as bioirrigation by benthic fauna. To improve the short-term prediction of the water quality and particularly the dynamics of algal blooms in the coastal areas of the Gulf of Finland, sediment phosphorus and especially hydrated iron oxides should be included in water quality models.
