Li Qiuhua

Distribution characteristics of mercury and methylmercury in phytoplankton at Guizhou Plateau reservoirs in winter

To understand the distribution characteristic and bioaccumulation factors(BAF) of total mercury(THg) and methylmercury(MeHg) in phytoplankton at Guizhou Plateau reservoirs,southwest of China.The phytoplankton and water samples were investigated at five reservoirs in the winter of 2012.The results showed that diatom was the dominant algae at Guizhou Plateau reservoirs in winter and phytoplankton abundance had obvious difference at the five reservoirs.The maximum phytoplankton abundance was about 29.05 × 104cells / L at Lake Baihua dam,and the minimum only 0.49 × 104cells / L at Sanbanxi Reservoir.The concentrations of THg and MeHg in phytoplankton were 29.29-277.07 ng / g(dry) and 1.12-10.93 ng / g(dry),respectively.The maximum concentrations of THg and MeHg in phytoplankton was at Lake Baihua.The BAF of THg and MeHg in phytoplankton were 1.42 × 104-9.78 × 104and 3.10 × 104-4.43 × 105,respectively.The maximum BAF in phytoplankton of THg was at Lake Baihua.The maximum BAF of MeHg in phytoplankton was at Lake Hongfeng.There was different effect on biological enrichment of mercury and methylmercury for different phytoplankton species composition.There were significant positive correlations between MeHg in phytoplankton and THg,MeHg,dissolved MeHg(DMeHg) in water.No significant correlation was found between MeHg in phytoplankton and the THg,DMeHg in water.MeHg was not only absorbed by phytoplankton.There were other factors influencing MeHg concentration in phytoplankton inevitably.There were significant negative correlations between MeHg in phytoplankton and environmental factors(SD,TN,NO-3-N).The degree of eutrophication had effects on MeHg concentration in phytoplankton.

Community structure of metazooplankton and its relationship with environmental factors at the estuary of Maixi River in Lake Baihua

In order to un derstand the dynamics and composition of metazooplankton community structure at the estuary of Maixi River in Lake Baihua,metazooplankton was investigated from August 2009 to August 2011.The results showed that there were 29 rotifer species with abundance ranging from 0.16 to 837.80ind./L.Only two kinds of copepoda,Mesocyclops thermocyclopoides and Harpacticella sp.were detected,the abundance range from 0 to 642.75ind./L.9 cladocera species were detected with abundances from 0 to 31.20ind./L.Metazoan zooplankton abundance was mainly composed by rotifer and copepods.The proportion of rotifer abundance was from 4.09% to 100%,comparing to the percentage of copepods being from 0 to 95.64%.Asplanchna priodonta,Asplanchna brightwelli,Brachionus diversicornis were the dominant species for rotifer,whosehighest abundance reached 424.88,392.20 and 61.99ind./L,respectively;Bosmina longirostris as the dominant specie of cladocera,with a maximum abundance of 27.93ind./L.Rotifer abundance was significant positive related to transparency,total nitrogen,nitrate nitrogen;while cladocera abundance exhibited a significant positive correlation with transparency and nitrate nitrogen,but significant negative correlation with the temperature.

Structure of phytoplankton community and its relationship with environmental factors at the estuary of Maixi River in Baihua Reservoir,Guizhou Province

Phytoplankton and environmental factors at the estuary of Maixi River in Baihua Reservoir were investigated monthly from July 2009 to June 2010.Results showed that there were 66 species(genus),which were mainly composed of the chlorophyta,bacillariophyta and cyanobacteria.The phytoplankton community was dominated by Pseudanabaena limnetica in summer and fall and by Cyclotella meneghiniana in winter and spring.The abundance of phytoplankton ranged from 1.17×104 to 3.35×107cells/L.The minimum phytoplankton abundance occurred in April of 2010,and the maximum occurred in July of 2009.The phytoplankton abundance composition was dominated mainly by cyanobacteria from April to September,but by bacillariophyta and pyrrophyta from October to March.Canonical correspondence analysis showed that temperature was the most important driving factor in regulating the composition and feature of phytoplankton community at the estuary.Nitrogen and phosphorus were the second important driving factors for the structure of phytoplankton community.Euglenophyta and a majority of cyanobacteria were affected by water temperature and turbidity,but chlorophyta and bacillariophyta were affected by the concentrations of nitrogen and phosphorus among these environmental factors.