Inter-annual changes of phytoplankton dominant species and biomass in a large shallow lake,Taihu China,were analyzed using the monthly monitoring data covering the period of 1991～2002.The concentrations of total nitrogen(TN),total phosphorus(TP) and phytoplankton chlorophyll-a(Chla) were used to explain the development of eutrophication in the lake.The results showed marked gradients of TN,TP,Chla and biomass in the lake from high values near the northern river input in the inner Meiliang Bay towards lower concentrations in the lake centre.Phytoplankton dominant species shifted from diatoms to cyanobacteria at the end of 1980's when the eutrophication started in the lake.Thereafter,almost no change in dominant species but phytoplankton biomass varied among years.Annual averages of TN,TP,Chla and biomass increased until 1996 declining thereafter possibly because of the controlling of wastewater discharge from the catchment by the local government.Microcystis-domination in phytoplankton assemblages presented the indication of eutrophication in Lake Taihu.Our results suggest that phytoplankton is a suitable ecological indicator for eutrophication development in large shallow lakes.
Small reservoirs play an important role in city fresh drinking water supply in South China.In order to understand the dynamics of trophic state and phytoplankton community in these reservoirs,Mutouchong Reservoir located in Zhuhai City,a typical small reservoir with a volume of 0.508 106 m3,was investigated in April,August and December,2006.The concentrations of TN,TP and chlorophyll a ranged from 0.34 to 0.71 mg·L-1,0.011 to 0.019 mg.L-1,9.18 to 21.1mg·m-3,respectively,and SD ranged from 0.6 to 1.5m.The TSIM index,based on the above four factors,ranged from 40 to 50,and indicated that the Mutouchong Reservoirs was mestrophic.52 species were observed and most of them were from Bacillariophyta and Chlorophyta.The biomass of phytoplankton ranged from 4.17 mg·L-1 to 5.38 mg·L-1,and the biomass in spring and summer was higher than that in winter.Phytoplankton was primarily dominated by Aulacoseira granulate and Monoraphidium sp.in spring,and then by Cosmarium spp.and A.granulate.in summer.In winter,filamentous cyanobacteria,Cylindrospermopsis rackiborskii became the dominant species,and this was possibly related to the decrease of nitrogen.In Mutouchong reservoir,nutrient was one of the possible factors controlling the seasonal variation of phytoplankton.
27 mustard materials were collected around Tibet and cluster analysis based on height of plant,stem diameter,branch position,amount of branch and numbers of siliqua properties was done in the present study.The results showed that: 1) At the threshold of 0.94,wild B.juncea germplasm in Tibet could be divided into 3 groups,mainly including branching type of above plant,branching type of below plant and average type,and the above results would be useful in rapeseed breeding;2)At the threshold of 0.61,they could be divided into 7 subgroups,namely SG1,SG2,SG3,SG4,SG5,SG6 and SG7,therefore,they could be considered as referenced markers of regional microclimate studing on crop growth environment in Tibet;3)It indicated that the agronomic characters of Tibet mustard germplasm were abundant,and their properties displayed significant differences.
The community and biodiversities of Rotifera,including species composition,density,biomass,biodiversity index and regression analysis were studied at six sampling stations(Ⅰ-Ⅵ) in the touring lakes,Ningbo.In one year study,21 species of rotifers were found.The annual average density of rotifers was 1782 ind.·L-1;biomass was 1.330 mg·L-1 and Margalef's biodiversity index was 0.740.Trichocerca pusilla and Polyarthra trigla were the dominant species in three touring lakes.Density and biodiversity index of rotifer in lake Dongqianhu were lower than those in the lakes Yuehu and Rihu.Regression analysis result showed that biodiversity index of rotifer had a negative linear relationship(r=-0.545,n=24,p<0.01)with water body pH value,and there was a significantly negative linear relationship(r=-0.668,n=16,p<0.01)between biodiversity index of rotifer and the community density in the lakes Yuehu and Rihu.
In this study,mussels(Anodonta woodiana woodiana) were chosen as the research object.We assessed the possible DNA damage in haemocytes of mussels using the single cell gel electrophoresisassay.Results showed haemocytes images which exposed to cadimium presented comet tails,compared the exposed groups with negative control group,existed significant differences.Mussels were exposed to different cadmium chloride concentrations(0,1,10,50 mg·L-1) respectively for 72 hours,the results showed that the average length of DNA migration and tai lDNA% in all exposed groups was significantly higher than that of negative control group(p<0.01) and existed significant dose-effect relationship.Otherwise,at the concentration of 10 mg·L-1,four time-effect groups(24,48,72,96 h) and a zero time control group were set up,the average length of DNA migration and tail DNA% under different exposed times in cadmium chloride was significantly higher than zero time group(p<0.01),but no significant time-effect relationship among the tested concentrations.
Effects of photosynthetic bacteria(PSB) on the aquiculture water quality such as chemical oxygen consumption(COD),ammonia nitrogen(NH4+-N),dissolved oxygen(DO) and pH were investigated.Besides,the effects of PSB on the composition of population of hydrobios including phycophyta and water bacteria were also estimated in our studies.The results showed that PSB could reduce the organic content and NH4+-N,but raise the DO content.At the same time,the phycophyta biomass could be affected by the PSB.In 0.50% group and 1% group,the phycophyta biomass was increased obviously.The proportion of the bacillariophuta was occupied up to 26%;the proportion of the chlorophyta was amounted to 60%;whereas the proportion of the cyanophyta decreased by 10%.Moreover,the composition of water bacteria population in the aquaculture water was effected by the PSB,with the proportion of vibrio and aeromonas decreasing obviously.
This paper proposes an index system to calculate the agricultural land use intensity of 30 provinces,autonomous regions,and municipalities in mainland China,and calculates the agro-climatic suitability by spatial interpolation.Based on this,by comparing the spatial relationship between them the obtained conclusions are as follows:(1) In general,the agricultural land use intensity in Eastern China is higher than Western China.Spatial distribution of the agro-climatic suitability is digressive from southeast to northwest of China.In a certain extent,the agro-climatic suitability restricts the distribution of agricultural land use intensity,but the spatial dependency can be changed by the improvement of agricultural land use intensity.(2) Overall the agricultural land use intensity in China has a rising trend from 1995 to 2005.The trend in lower agro-climatic suitability regions is more remarkable.(3) Based on the relationship between agricultural land use intensity and suitability of agro-climate,suggestions were made to make intensive management of agricultural land by adjusting measures to local conditions.
Regionalization of ecological function is the basis for understanding the function of ecosystem,evaluating the differences and characteristics of ecosystem and framing countermeasures for resuming degrade ecosystem.In this paper,based on the synthetically analysis of the characteristics of ecological environments of Jiangxi Province,the 80 administrative units are consider as the regionalization objects,the principles of ecological regionalization were adopted,indices of ecological regionalization were proposed,and a comprehensive method of combing quantitative analyses and qualitative analyses were utilized for the three levels units of the whole province.The main quantitative analyses is performed on the DPS7.05,it includes cluster analyses and principal component analyses;the quantitative analyses includes superimpose graphics,leading factors and intelligent determination were used to optimize the subarea borderline.Geographical information systems(arcview GIS3.03) were taken into account to chart map.The results shows that Jiangxi Province could be ecological characterized as 4 ecoregions,13 sub-ecoregions and 45 eco-functional zones.The results of this research have a significant value to the maintenance of ecological security,ecological programming and eco-environmental protection of Jiangxi Province.
Land is the carrier of various terrestrial ecosystems,while land use is an indispensable activity to human's living and development.It is also the interaction area between human being and nature,so the change of land use cover would impact the structure and function of ecosystem unavoidably.Based on the Constanza's ecosystem service value theory and using the coefficients advanced by Xie Gao-di and co-works,who made a table listing the ESV of unit area in land ecosystem and providing the average unit price of ESV in China,this paper calculated the change of the ecosystem service values(ESV) in 1996 and 2005 of Guangzhou City,Guangdong Province respectively.The results showed that the ESV had been changed a little and increased 108 million yuan RMB from 1996 to 2005 due to the change of cropland and other agricultural lands to residential and water lands and the high ecosystem value coefficient(VC) of water,while the average ESV(Ave(ESV))dropped 30.11 percent due to the expansion of residential and commercial land.The calculation also indicated that the coefficients of sensitivity(CS) were all inelastic.The change of cropland impacted the security of foodstuff of Guangzhou City,while the change of water mainly influenced the ecosystem service function.
Saltwater intrusion is a natural phenomenon in littoral.In recent years,the disaster of saline water intrusion has arisen continually at stream outlet area of the Pearl River Delta(especially in Macao),which has brought on lack of water supply to millions of people.Due to the potentially social and economic impact of the disaster,more and more people are paying attention to saline water intrusion.In this paper,the authors had analyzed the causations and the damages of saline water intrusion in Macao,and proposed that the environmental factors(e.g.,drought and sea level rise) were the major inducement and that human activities have accelerated these processes.At the same time the authors had put forward some solutions to prevent saline water intrusion.
