水位调控对河口沉积物磷赋存及生物可利用性的影响

Impacts of Water Level Regulation on Estuary Sediment Phosphorus Storage and Bioavailability

以丹江口库区神定河河口持续淹水和间歇淹水积物为对象,探讨水位调控前后不同淹水沉积物的理化性质、磷赋存及生物可利用性变化规律。实验持续3个水位调控循环,水位变化速率分别为0,3,6 cm/d。结果表明:水位调控总体上促使沉积物OM流失和p H值升高。与对照速率(0 cm/d)相比,3 cm/d和6 cm/d水位变化使无定形铁氧化物分别增加了185.56%~204.92%(持续淹水沉积物)和185.28%~228.76%(间歇淹水沉积物)。水位调控后,持续淹水和间歇淹水沉积物的可交换态磷(Ex-P)、铝结合态磷(Al-P)、铁结合态磷(Fe-P)、钙结合态磷(Ca-P)和总磷(TP)含量均上升,OM流失降解和闭蓄态磷(O-P)活化转化造成有机磷(Org-P)和O-P含量降低。水位调控有利于Org-P和O-P转化为活性磷,因此应将二者也视作沉积物生物可利用性磷组分。

Continuously submerged and intermittently submerged sediments collected from Shendinghe River estuary of Danjiangkou reservoir,were employed to conduct the dynamic water level（ WL） regulation experiments with 3rates of change of water level（ 0 cm. d^（- 1）,3 cm. d^（- 1）and 6 cm. d^（- 1））. The whole experiments lasted three WL regulating cycles（ nearly four months） and each single cycle included four WL dynamic phases： decline,stable,ascend and re-stable. The results show that： WL regulation promotes OM loss of sediment and results in the increase of p H value. When compared with the data without WL regulated control,3 cm. d^（- 1）and 6 cm. d^（- 1）WL regulations lead to the increase of 185. 56%- 204. 92%（ continuously submerged sediments） and185. 28%- 228. 76%（ intermittently submerged sediments） in concentrations of amorphous iron oxides,respectively. Furthermore,after WL regulation,concentrations of exchangeable phosphorus（ Ex-P）,aluminum bounded phosphorus（ Al-P）,iron bounded phosphorus（ Fe-P）,calcium bounded phosphorus（ Ca-P） and total phosphorus（ TP） increase in intermittently submerged and continuously submerged sediments,whereas OM loss,occluded phosphorus（ O-P） activation and transformation,greatly contribute to the decline of organic phosphorus（ Org-P） and O-P in sediment. With respect to the activation of Org-P and O-P under WL regulation,both of the two phosphorus fractions should be categorized into bio-available phosphorus components.