底栖藻类对消落带土壤中各形态磷的影响

为揭示底栖藻类对三峡库区消落带淹没初期土壤中不同形态磷的影响作用，开展了相关的模拟实验。结果表明，在模拟的底栖藻类影响条件下，消落带土壤中铝磷（Al-P）的含量在实验期间处于波动状态，Al-P相对于其余形态的磷更易于被藻类吸收利用，且与藻类生长存在密切相关，即底栖藻类生长状态较好时，土壤中Al-P呈现下降趋势；而生长状态较差时，土壤中Al-P又出现略微上升的趋势。在实验后期土壤中Al-P含量上升，可能是其余形态的磷转化而来。底栖藻类的生长对不同深度土壤中铁磷（Fe-P）的影响不同，其生长对2-4 cm层土壤的影响较大，而对其余层影响不大。不同深度土壤中闭蓄态磷（O-P）和钙磷（Ca-P）含量差异不明显。实验后期Fe-P、O-P和Ca-P含量一直呈现下降的趋势，只有Al-P在后期出现上升的趋势，说明在淹水条件和底栖藻类生物膜共同作用下，土壤磷的有效性提高，土壤中难溶性磷向易溶性磷转化。  

INFLUENCE OF BENTIC ALGAE ON THE PHOSPHORUS FRACTIONS IN SOILS IN WATER-LEVEL-FLUCTUATING ZONE

To study the effects of benthic algae on the phosphorus (P) fractions in the submerged soils in water-level-fluctuating zone of the Three Gorges Reservoir (TGR), simulated experiments were conducted under indoor conditions. The results indicated that benthic algae utilized more AI-P compared with other forms of P, and the growth of the algal was inversely related to the AI-P content that the Al-P content decreased when the conditions were suitable for algal growth. Moreover, benthic algae variously affected the iron-phosphorus (Fe-P) in different layer of soil. Benthic algae had the greatest effects on Fe-P on 2-4 cm layer. In addition, the contents of O-P and Ca-P in different soil depths showed no significantly changes. In the late period of this experiment, the contents of Fe-P, O-P and Ca-P all showed a declining trend whereas Al-P showed a sign of increasing. Impoundment of TGR and benthic algae biofilm significantly increased P availability in the submerged soil and enhanced the transformation of inorganic-P into more soluble fractions.