School of Environmental and Chemical Engineering, Shanghai University, P.O. Box 144, 99Shangda Road, Baoshan, Shanghai, 200444, China.
Tianjin University, 92 Weijin Road, Nankai, Tianjin, 300072, China.
Environ Sci Pollut Res Int. 2017 Sep;24(25):20330-20341. doi: 10.1007/s11356-017-9537-9. Epub 2017 Jul 13.
The Xin'an Reservoir is an important water supply source and water conservation area for the Qiantang River. However, after the occurrence of the two algae blooms in 1998 and 1999, the safety of water quality has been put into question. In order to study the historical deposition of nutrients, sediment cores were collected in different regions from the Xin'an Reservoir. The stable isotopes δC and δN, nutrients, total organic carbon (TOC), and inorganic carbon (IC) in the sediment cores were determined. Radiometric methods (Pb and Cs) were used to obtain sediment chronologies. Spatially, it was found that the average total nitrogen (TN) content in the upper 5 cm of sediments increased from 0.21% in the riverine zone, to 0.33%, and then to 0.57% in the lacustrine zone. The average TP content in the upper 5 cm increased from 0.67 g kg in the riverine zone, to 1.03 g kg in the estuary region, and then to 1.65 g kg in the lacustrine zone. In addition, TOC levels showed a distinct increase from 1.42% in the bottom to 5.97% in the surface of the lacustrine zone. These results demonstrated that although primary productivity and the input of nutrients constantly increased in recent years, algae blooms rarely occurred in the Xin'an Reservoir, due to "depth effect" and an aquatic environment protection-oriented fishery policy. However, high TOC flux and high bio-available phosphorus and nitrogen in surface sediment demonstrated that the reservoir is still confronted with the potential risk of algae blooms.
新安江水库是钱塘江的重要供水水源和水源涵养区。然而，在 1998 年和 1999 年发生两次藻类水华事件后，其水质安全受到了质疑。为了研究营养物质的历史沉积，在新安江水库的不同区域采集了沉积物岩芯。对岩芯中的稳定同位素 δC 和 δN、营养物质、总有机碳（TOC）和无机碳（IC）进行了测定。利用放射性方法（Pb 和 Cs）获得了沉积物年代序列。从空间上看，发现河流区沉积物上层 5cm 内总氮（TN）的平均含量从 0.21%增加到 0.33%，再增加到 0.57%；上层 5cm 内总磷（TP）的平均含量从河流区的 0.67g/kg 增加到河口区的 1.03g/kg，再增加到湖湾区的 1.65g/kg。此外，TOC 水平从湖湾区底部的 1.42%明显增加到表面的 5.97%。这些结果表明，尽管近年来初级生产力和营养物质的输入不断增加，但由于“水深效应”和以保护水生环境为导向的渔业政策，新安江水库很少发生藻类水华。然而，高 TOC 通量和高生物可利用磷和氮表明水库仍面临藻类水华的潜在风险。
