Geochemical records of the sediments and their significance in Dongping Lake Area,the lower reach of Yellow River,North China

Dongping Lake area,located in the lower reaches of Yellow River,is an ideal place to study the changes of modern river and lake sedimentary environment.The sediment samples of Dawen River,Yellow River,and Dongping Lake were collected,and the major elements,trace elements and organic matter geochemical composition of the samples were analyzed.Cluster analysis,characteristic element ratio method and graphic method were used to explore the geochemical characteristics of sediments and their environmental implication.The results show that the contents of SiO_(2),Na_(2)O,TiO_(2) and Zr in sediments of Dawen River and Yellow River are relatively high,and the contents of iron and manganese oxides,organic matter,CaO,P2O5 and Sr in lake sediments are relatively high.That reveals the differences of sedimentary environments between the rivers and the lake.The contents of Sr and Zr in Dawen River are affected by the rapid migration of clastic materials in the upstream carbonate source area during the flood season;the δCe,ΣREE and REE’s ratios in the sediments of the Yellow River reflect the influence of the Loess source;and the distribution of elements changes along the flow direction during the flood season.The characteristics of pH,element composition and LREE&HREE fractionation of the lake sediments indicate that the sediment source is complex,and the lake environment is affected by the flood season.The study shows that the geochemical content and its variation characteristics of sediments effectively reveal the sedimentary environment,material composition and characteristics of flood season of rivers and the lake in the study area.

Hydrobios and Control of Eutrophication in Dongping Lake,Shandong Province

The Hydrobios in Dongping Lake, Shandong Province, mainly includes phytoplankton, zooplankton, benthic animals, fishes and hydrophytic vascular plants. Nitrogen and phosphorus are the restrictive factors for the growth and propagation of hydrophyta, therefore the key to the prevention and control of eutrophication in lakes lies in the control of the contents of the two elements in the water. Artificial fishing of algae can reduce the concentrations of trophic substances such as nitrogen and phosphorus in the water bodies, and biological measures may decrease the contents of these trophic substances in the bottom sediments and the water bodies, thereby playing an active role in modifying the eutrophication of the lake.

Analysis on the Influencing Factors and Comprehensive Management of Environmental Problems in Dongping Lake

[Objective]We aimed to study the influencing factors and comprehensive management of environmental problems in Dongping Lake.[Method]Based on field investigation and historical data,environmental problems of Dongping Lake and their influencing factors were analyzed,and seven measures about comprehensive management of environmental issues and ecological protection of Dongping Lake were put forward.[Result]During recent years,the content of total nitrogen and total phosphorus in Dongping Lake showed a decreasing trend,but the water was still in the eutrophic state.The environmental problems of Dongping Lake,like flood,drought and pollution,are closely linked to natural and man-made factors,such as regional seasonal precipitation,industrial and agricultural pollution,etc.In order to control the environmental problems of Dongping Lake,we should strengthen the construction and management of wetland nature reserves,develop ecological agriculture,establish an integral system for environmental monitoring and information management,reinforce propaganda and education to improve residents’ environmental consciousness,etc.[Conclusion]The research could provide scientific references for the comprehensive management of environmental problems in Dongping Lake and its basin.

Karyotype Analysis of Cyprinus carpio in Dongping Lake

To investigate the genetic composition of the carp （Cyprinus carpio） in Dongping Lake and to provide eytogenetie data for exploration, protection and appropriate utilization of the germplasm resources, karyotype of the carp was analyzed in this study. In detail, colehieine was given to the fish an intraperitoneal route 24 h after the intraperitoneal injection of phytohemagglutinin （PHA） solution to arrest cells in metaphase. The kidney cells were collected for the preparation of chromosome specimens, which were observed under a microscope. Ten cells having correct number of chromosomes and clear morphology were photographed and zoomed to measure the relative length, arm ratio, ann number （NF） and other parameters of chromosomes. The results showed that the chromosome number of C. earpio in Dongping Lake was （2n = 100） ; the karyotype formula was （2n =20m ＋38sm ＋20st ＋22t）. The total number of chromosome arms （NF） was 158. By comparing the karyotype of Dongping Lake carp with that of other Cyprinus species, we concluded that Dongping Lake carp is more highly evolved among Cyprinus species.

Environmental factors influencing cyanobacteria community structure in Dongping Lake, China

The present study was conducted to provide a detailed understanding of the variation in cyanobacterial communities of Dongping Lake, which is the final water volume adjusting and storing lake in the east route of the South-to-North Water Diversion Project in China. The spatial and temporal distribution of cyanobacteria was assessed from May 2010 to October 2012 based on monthly samples collected from three stations. Over the 30-month survey, 15 genera and 25 species of cyanobacteria were identified, with cyanobacterial abundance at each monitoring station ranging from undetected to 3.04×10^7 cells/L, average of 4.27×10^6 cells/L. The dominant cyanobacterial species were Pseudanabaena limnetica and Aphanizomenon issatschenkoi and not the usual bloom-forming genera such as Microcystis and Anabaena. Cyanobacterial community structure and water quality variables exhibited substantial changes over the period of survey. Redundancy analysis, Pearson correlations, and regression analysis were applied to analyze the relationships among the variables. The results suggested that temperature and chemical oxygen demand were key drivers of the cyanobacterial community composition in Dongping Lake. In addition, the concentration of inorganic nitrogen in the lake had a profound effect on the cyanobacterial abundance as a non-limiting factor in warm periods.

Metal release/accumulation during the decomposition of Potamogeton crispus in a shallow macrophytic lake

Changes in metal concentrations in the litter of Potamogeton crispus were monitored during a consecutive 40-day in situ decomposition experiment using the litterbag method.The accumulation index was calculated and used to indicate the changes in the metals in litter.The results showed that the concentrations of Al,Cd,Cr,Fe,Mn,and Pb in litter increased significantly during the decomposition,while Cu and Zn concentrations decreased dramatically.Significant positive correlations were found between the concentrations of Al,Cr,Fe,and Mn and between Cu and Zn.Moreover,Cu and Zn both negatively correlated with Al and Fe.The remaining dry mass was negatively correlated with Al and Fe concentrations but positively correlated with Cu and Zn concentrations.Generally the accumulation index values of metals other than Al were less than one,indicating that the litter of P.crispus acted as a source of metals to the surrounding water body.Al was the only metal that showed continuous net accumulation in litter.The net accumulation of Fe and Mn in litter during the last 10 days of the experiment may indicate the precipitation of Feand Mn-oxides.It was estimated that 160 g/m^2（dry weight）P.crispus was decomposed in40 days.This was equivalent to releasing the following amounts of metals：0.01 mg Cd,0.03 mg Cr,0.71 mg Cu,0.55 mg Mn,0.02 mg Pb and 13.8 mg Zn into surrounding water,and accumulating 149 mg Al and 11 mg Fe,in a 1 m^2 area.