Yin Da-qiang

Allelopathic Effects of Four Submerged Macrophytes on Microcystis aeruginosa

Allelopathic inhibition activities of four submerged macrophytes (Potamogeton maackianus, Vallisneria spiralis, Elodea nuttalli Ceratophyllum demersum) on Microcystis aeruginosa are investigated by a series of experiments in a short-term bioassay. Individual algal test reveals culture solution of P. maackianus and C. demersum have better effects on algal growth inhibition. Furthermore, continuous addition assays show strong growth inhibition by culture solution. Inhibitory activity is different in aquatic extracts from different section of P. maackianus. Removing the disturbance of microorganism by autoclaving influences algal assay. These results provide that unstable and excreting continuously allelopathic compounds by submerged macrophytes are the primary cause of algal growth inhibition. Interference with algal growth experiments was investigated in microorganism and nutrient elements of nitrogen and phosphorus.

Plant-promoted dissipation of four submerged macrophytes to phenanthrene.

In order to investigate the function of submerged aquatic plants for recovery of water polluted by typical organic pollutants, and select potential plants for phytoremediation of polycyclic aromatic hydrocarbons contaminated water, removal efficiencies of four submerged macrophytes to phenanthrene were investigated, following 40-day exposure to phenanthrene solutions in an outdoor-simulated experiment. During the exposure period, phenanthrene concentration in water, sediments and the roots of submerged macrophytes were observed. Results showed that Elodeacanadensi exhibited the highest concentrations in roots, while Ceratophyllum demersum contained the lowest among these four submerged macrophytes. The disparity of phenanthrene in roots would come from plant properties including the shape and surface area of both shoots and roots. These plants enhanced the remediation of phenanthrene in solution through plant-promoted sedimentation and biodegradation. Potamogetoncrispu and Elodeacanadensi showed the higher performance to remove phenanthrene due to plant-promoted biodegradation.

Biogeochemicai cycling of nitrogen in lakes and the role of microorganisms in conversion of nitrogen compounds

It is generally considered that nitrogen is one of the major factors regulating the trophic status of lakes, and the biogeochemical cycling of nitrogen serves the most important function in lake systems.Lakes often receive large anthropogenic inputs of nitrogen that cause eutrophication,and the exchange of nitrogen-compounds between sediment and water has a profound effect in all kinds of lakes.Such increased nutrient loading promotes the growth of phytoplankton while rooted plants and benthic are suppressed due to reduced light availability,the transfer of the nitrogen through the food chains in algal lake and macrophytic lake is different accordingly.Meanwhile,in this re- view progresses made on the processes such as nitrification,denitrification,nitrogen fixation and anammox(anaero- bic ammonium oxidation)are emphasized.Methods and techniques applied in the research of biogeochemical cyc- ling of nitrogen are also summarized,and the development of molecular techniques has contributed enormously to the rapid recent progress in the field.Current insufficiencies are pointed out and future directions are recommended in the end.

Study on eco-remediation in urban-ponds:restoring submerged macrophytes

In allusion to the algal eutrophication problem of urban shallow lakes,four enclosures were set up in an urban eutrophic pond of Nanjing City to restore submerged maerophytes communities.Results showed that Eichhor- nia crassipes can be used to improve the transparency of water body,and its effect was relative to its coverage when its coverage was less than 0.3.With the coverage no less than 0.3 Eichhornia crassipes can make transparency im- proved from lower than 0.3m to higher than 0.6m during 30 to 40 days in summer.The submerged vegetation was availably restored after transparency improved to higher than 0.6m.Compared to the period without submersed veg- etation,the transparency of the water body was enhanced 70% and Chl.a concentration were reduced 50% corre- spondingly.

Free radical generation and stress effect on Scenedesmus obliquus exposed to phenanthrene

通过静态模拟实验,研究不同浓度（0.005、0.01、0.025、0.05和0.1 mg/L）菲暴露96 h后,对斜生栅藻的生长、自由基含量、抗氧化系统以及脂质过氧化产物（MDA）的影响.结果表明,0.01 mg/L菲开始对藻细胞生长产生显著抑制作用,在此浓度下电子自旋共振检测到的自由基信号（g=2.0033,幅宽10.15 mT）显著增强;在浓度设置范围内,超氧化物酶歧化酶、过氧化物酶、谷胱甘肽-S-转移酶活性均被显著诱导,显示出抗氧化系统的应激机制.谷胱甘肽和MDA含量均在0.025 mg/L时被显著诱导.这说明斜生栅藻对菲暴露比较敏感,0.01 mg/L即已显示胁迫效应,自由基的诱导是斜生栅藻产生损伤的重要原因,藻细胞的生长量是比较敏感的损伤指标.