Effects of temperature and nutrients on phytoplankton biomass during bloom seasons in Taihu Lake

Long-term variations of phytoplankton chlorophyll-a （Chl-a）, nutrients, and suspended solids （SS） in Taihu Lake, a large shallow freshwater lake in China, during algal bloom seasons from May to August were analyzed using the monthly investigated data from 1999 to 2007. The effective accumulated water temperature （EAWT） in months from March to June was calculated with daily monitoring data from the Taihu Laboratory for Lake Ecosystem Research （TLLER）. The concentrations of Chl-a and nutrients significantly decreased from Meiliang Bay to Central Lake. Annual averages of the total nitrogen （TN）, total phosphorus （TP）, and Chl-a concentrations, and EAWT generally increased in the nine years. In Meiliang Bay, the concentration of Chl-a was significantly correlated with EAWT, ammonia nitrogen （NH4＋N）, TN, the soluble reactive phosphorus （SRP）, TP, and SS. In Central Lake, however, the concentration of Chl-a was only correlated with EAWT, TP, and SS. Multiple stepwise linear regression revealed that EAWT, dissolved total phosphorus （DTP）, and TP explained 99.2% of the variation of Chl-a in Meiliang Bay, and that EAWT, NH4＋-N, and TP explained 98.7% of the variation of Chl-a in Central Lake. Thus EAWT is an important factor influencing the annual change of phytoplankton biomass. Extreme climate change, such as extremely hot springs or cold springs, could cause very different bloom intensities in different years. It is also suggested that both nutrients and EAWT played important roles in the growth of phytoplankton in Taihu Lake. The climate factors and nutrients dually controlled the risk of harmful algal blooms in Taihu Lake. Cutting down phosphorus and nitrogen loadings from catchments should be a fundamental strategy to reduce the risk of blooms in Taihu Lake.

Synthesis of fluorescent bisboronic acid sensors and their recognition of mono-/oligo-saccharides

Sensors capable of recognizing cell surface carbohydrates,such as sialyl Lewis X（sLe-x）,are invaluable research tools and for the diagnosis and early detection of many forms of cancer.In this paper,we report the design and synthesis of a series of bisboronic acids 6（a-f） as fluorescent sensors towards mono-/oligosaccharides.Among them,compounds 6d and 6e showed strong binding affinities with glucose and fructose,while compound 6c,in which two anthracene-based boronic acid units were linked by a hexamethylene spacer,was able to recognize sLe-x selectivity and stained HEPG2 cells at 1 μmoI/L.