The Spatial Distribution Of Phosphorus And Diatoms In Sediments Of Three Reservoirs In Southern China

Reservoirs are man-made water bodies in which hydrodynamics are strongly regulated by human. The deposition of suspending grain and the distribution of sediments in reservoirs are different from those in natural water bodies. However, knowledge on formation and spatial distribution of sediments in reservoirs remains scarce. In this article, three typical reservoirs located in the north regions of tropics, Dajingshan Reservoir, Liuxihe Reservoir and Xinfengjiang Reservoir, are investigated to understand the spatial distribution of phosphorus and diatoms in the sediments.Dajingshan Reservoir is a pumped storage reservoir. Most water was pumped from a heavily polluted river. Sediment columns were collected at seven sites. The total volume of sediment in the whole reservoir was estimated to be about 48840m³ and the total drought weight was about 36137 tons. Inorganic species of phosphorus represented different vertical distribution, and their coefficient of variance had an order Fe-P>Al-P>Ca-P>Oc-P. Among inorganic species of phosphorus, the content of O-P was the highest, followed by Fe-P, Ca-P and Al-P. The total inorganic phosphorus (TP_I), total nitrogen (TN) and releasable phosphorus (P_re) in the sediment were estimated to be 21886kg, 67015 kg and 5867 kg, respectively. The contents of TP_I, TN and P_re decreased from the dam to the upper reach of reservoir, reflecting the hydrodynamic effects on sediment distribution. The contents of IP, TN and P_re in the sediments increased vertically from bottom to surface of the sediment cores, especially from depth 18cm to 6cm in core from middle reservoir, timely corresponding to the development of the urban and economic of Zhuhai City from the middle of 1980s' to 2000.Liuxihe Reservoir is a hill type of reservoir. The spatial distributions of the phosphorus in the sediments were different at the four sampling sites, LUtian riverine zone(Sl), Yuxi riverine zone(S2), the transition zone(S3) and the lacustrine zone (S4). The content of TP, OP, IP, HC1-P and Al-P at the four sites had the order: S1>S3>S4>S2. The content of NaOH-P had the order: S3>S1>S2>S4, and the content of Fe-P had the order: S3>S4>S1>S2. The average ratio of IP/OP...