College of Resources and Environmental Science, South-Central University for Nationalities, Wuhan, 430074, China.
Yunnan Key laboratory of Pollution Process and Management of Plateau Lake-Watershed, Yunnan Institute of Environmental Science, Kunming, 650034, China.
Environ Sci Pollut Res Int. 2018 May;25(14):13579-13588. doi: 10.1007/s11356-018-1517-1. Epub 2018 Mar 1.
The phosphorus (P) release from bloom-cyanobacterium during its decline period is one of the most important parts involved in lake P-biogeochemical cycle, which is an important nutrient self-regulating process to sustain eutrophic status in lakes. An in situ experiment was set up to study the phosphorus release mechanisms of cyanobacterial blooms in Dianchi Lake during its decline period. In the enclosure, the cyanobacteria were dying out gradually and this process further affected the water quality parameters and lead to P release from bloom-cyanobacteria. The pH and electric conductivity (EC) increased substantially, while the redox potential (ORP) decreased during the whole experimental period. Among all the released P forms, the orthophosphate (ortho-P) was the main released P form and accounted for 96.7 and 67.8% of the total phosphorus (TP) increment in the water and the TP reduction in algae respectively. According to the TP in sediment and lost P of overlying water column, it could be concluded that the ortho-P released from algae was absorbed by sediment as well. The release of TP, organic P (OP), and ortho-P from bloom-cyanobacteria all followed the first-order kinetics, and the release rate of ortho-P was much higher than that of OP (p < 0.05). Furthermore, according to the total extracellular polysaccharide (EPS) determination and related Pearson's correlation analysis, the release of TP and ortho-P from bloom-cyanobacteria would probably depend on the reduction of capsular polysaccharide (CPS) and colonial sheath disaggregation. In conclusion, a large amount of ortho-P was released and adsorbed by sediment gradually during cyanobacterial bloom decline period, and these bioavailable P could provide the sufficient nutrient for newborn cyanobacteria and could contribute to the construction of a new internal P cycle among sediment, water, and cyanobacterial bloom.
在水华蓝藻衰退期，磷（P）的释放是湖泊 P 生物地球化学循环的重要组成部分之一，这是维持湖泊富营养化状态的重要营养自我调节过程。本研究采用原位实验，研究滇池水华蓝藻衰退期的磷释放机制。在围隔内，蓝藻逐渐死亡，这一过程进一步影响水质参数，导致水华蓝藻释放磷。整个实验过程中，pH 和电导率（EC）显著升高，而氧化还原电位（ORP）降低。在所有释放的磷形态中，正磷酸盐（ortho-P）是主要的释放磷形态，分别占水中总磷（TP）增量和藻类中 TP 减少量的 96.7%和 67.8%。根据沉积物中的 TP 和上层水柱中损失的 P，可以得出结论，藻类释放的 ortho-P 也被沉积物吸收。TP、有机磷（OP）和 ortho-P 从水华蓝藻中的释放均遵循一级动力学，ortho-P 的释放速率远高于 OP（p < 0.05）。此外，根据总细胞外多糖（EPS）的测定和相关 Pearson 相关性分析，TP 和 ortho-P 从水华蓝藻中的释放可能取决于囊多糖（CPS）的减少和群体鞘的解体。总之，在水华蓝藻衰退期间，大量的 ortho-P 逐渐被沉积物释放和吸附，这些生物可利用的 P 可为新生蓝藻提供充足的营养，并有助于构建沉积物、水和水华蓝藻之间新的内部 P 循环。
