Abstract:Recently,restoration and reclamation of vegetation in degraded wetland ecosystem have become a hot subject.As a reservoir of past plants,seed bank has huge potential for natural re-generation of wetland vegetation.In this review,we provided an overview of the major researches and progresses in the wetland seed bank formation,size and spatial pattern,species composition and relationships between seed bank and standing vegetation at home and abroad.Some case studies of wetland restoration using soil seed bank are introduced here,especially focused on main factors affecting seedling emergence of soil seed bank,safe sites for establishment of seedling and restoration potential of soil seed bank.We further discussed the main problems presented in the wetland re-vegetation from soil seed bank at present research and its possible direction of future studies.This review is expected to be a key reference for the development in the theory and practical techniques of restoration of wetland vegetations from soil seed bank.

Abstract:Field pilot tests of modified local soil/sand induced ecological restoration technology (MLS-IER) were carried out in the experimental enclosure of Meiliang Bay of Lake Taihu.The response of zoobenthos community in the experimental areas was evaluated based on the results of the survey from November 2010 to September 2011.The results revealed that the average density and biomass of mollusca in the experimental area were improved by 124% and 33.8%,respectively,and the average Shannon-Wiener index and Margalef index of zoobenthos were improved by 41.1% and 18.5%,respectively,compared to the control area.Canonical correspondence analysis was employed to identify the relationship between environmental factors and zoobenthos community.Chlorophyll-a,temperature,dissolved oxygen and total phosphorus concentration were found to be significant factors that influenced the zoobenthos community.This study indicated that the habitat and species diversity of the zoobenthos can be improved by the reduction of Cyano-HABs and nutrient levels,and the increase in dissolved oxygen due to the MLS-IER treatment in the enclosure.

Abstract:Restoration of submersed vegetation is generally considered as an effective long-term approach to improve the water quality of eutrophic lakes,and chitosan-modified soil has been used to rapidly improve the water quality in the recent years.In this study,an experiment with four treatments(the control,submersed macrophyte,submersed marcophyte+soil,and soil) was carried out in the hypereutrophic water(Meiliang Bay) in Lake Taihu during May to December in 2011,with the aim to develop a macrophyte-mediated approach to improve water quality.During the period of the experiment,submersed vegetation had a final coverage of 13.0% and 52.3% in the submersed macrophyte and the submersed macrophyte+soil treatments,respectively.The indices of water quality were measured in 3-day intervals.The results showed that the soil was effective to improve the water quality,with a decrease in the contents of TP by 74.6%,TN by 20.7%,PO₄^3--P by 31.0%,Chl.a by 80.4% and an increased SD by 90.4% as compared to the control;the submersed marcophyte+soil treatment was the most effective way to decrease the contents of TP (64.0%),TN(36.2%),PO₄^3--P(28.6%) and Chl.a(71.1%),and increased the SD(76.4%).The submersed marcophyte restoration alone did not improve the water quality.The submersed marcophyte+soil treatment was also the most effective one among the three treatments to decrease the contents of TN(15.6%),TP(61.7%),PO₄^3--P(55.8%) and NH₄⁺-N(82.8%) in the sediment interstitial water.The study implies that restoration of submersed vegetation with the aid of chitosan-modified soil be an effective technology to improve the water quality,although the effectiveness needs to be further evaluated on a long-term basis.

Abstract:To determine the NH₄⁺-N release from polluted river channel sediments,water and sediment samples were collected.We examined sedimentary NH₄⁺-N release under two aeration conditions: aerating to water (EW) and aerating to sediments (ES).The experimental results showed that the effect of NH₄⁺-N removal in ES was higher than that in EW,which removed the NH₄⁺-N both from pore water and sediments.In the ES group,the concentrations of NH₄⁺-N in sediment and pore water were decreased by 63.39% and 43.33%,respectively.However,the values of NH₄⁺-N in sediments and pore water were merely decreased by 7.54% and 13.98%,respectively,in the EW group.The variation of the diffusion flux of NH₄⁺-N was similar between the control group and the EW group across the sediment-water interface,with the value of the EW higher than that of the control group.The diffusion flux of NH₄⁺-N in the ES group was completely different from the other two groups.Throughout the trial period(other than section 5 d),the value of flux in the ES group was lower than that in the EW group,and the lowest concentration was showed up in the first 15 d.The value was 13.73 mg/(m²·d),which just accounted for 14.68% in the EW group and 19.93% in the control group,respectively.Our results indicated that the NH₄⁺-N in the cores of sediment aeration group had a lower release potential than that in the cores of water aeration group.

Abstract:The investigation of the taste and odor compounds in Lake Taihu,from June 2009 to May 2010,included MIB,GEO, β-cyclocitral and β-ionone.Given comprehensively consideration to various environmental factors and cyanobacteria taxa,we analyzed the relationships between two forms of odors and some key environmental factors closely related with these odors.It was found that dissolved MIB and particulate β-cyclocitral,β-ionone were the main odors,and they made great contributions or potential contributions to odor problems in Lake Taihu.Combining previous studies with this investigation,it was estimated that the variations of production and release velocities of the odors,microbe degradations,photolysis,absorption and volatilization led to the weak relationships between the dissolved odors and the particulate ones.Microcystis and chlorophyll-a had close relationships with taste and odor compounds in Lake Taihu.Cyanobacterial blooms had important influences on occurrences of the taste and odor compounds in Lake Taihu.For managing the occurrences of taste and odor events,it is very critical to control cyanobacterial blooms.

Abstract:Primary production,chlorophyll-a and alkaline phosphatase activity of periphyton can indicate its water purifying capacity.Five artificial substrates with different surface configurations and physicochemical characteristics were selected during this experiment.They were glass slide,PVC film,soft substrate,combined substrate and elastic substrate.The primary production, chlorophyll-a and alkaline phosphatase activity of periphyton attached on these five different substrates were investigated in situ.The results showed that physicochemical characteristics of artificial substrates were proved to be the key factors affecting the stability of periphyton community,primary production,chlorophyll-a and alkaline phosphatase activity.Generally during in situ attachment process,the maximum mass of periphyton appeared on the 8th to 10th day while periphyton primary production,chlorophyll-a and metabolic activity were also showed the highest.Primary production,chlorophyll-a and alkaline phosphatase activity of the periphyton attached on elastic and soft substrates were significantly higher than those on other three substrates.The net primary production of the periphyton attached on the elastic substrate was 164.21 mgO₂/(g·h),the highest of those on the five artificial substrates.Compared with the soft substrate,the elastic substrate was more economic and better optimal artificial substrate for water quality restoration.

Abstract:The anaerobic decomposition of high-density cyanobacteria and the kinetics of contaminants release were investigated based on a set of batch tests in this study.The results showed that the degradation rates of chlorophyll-a(Chl.a were 0.074, 0.133,and 0.081 d^-1,respectively,at different cyanobacterial densities of 2.23×10¹²,1.19×10¹³ and 4.47×10¹³ cells/L, respectively.The chemical oxygen demand increased while the UV₂₅₄ value increased initially and then decreased,suggesting that the release of organic compounds increased,but the molecules of which were reduced gradually during the degraded process.Accordingly, the pH of incubation solution remained acidic and the conductance increased,up to 949 μS/cm.The decomposition of cyanobacteria resulted in a high release of nitrogen and phosphorus.Moreover,dissolved organic nitrogen was degraded gradually into inorganic nitrogen form,in which the amount of ammonia nitrogen accounts for 90%.The results demonstrate that the anaerobic decomposition of high-density cyanobacteria can release a large amount of organic compounds and nutrients into water,furthermore the release of contaminants increases with the increasing density of cyanobacteria.Therefore,to avoid high-density cyanobacteria deteriorating water quality and even threatening drinking water safety,we need to remove cyanobacteria timely when algal bloom occurs in the lake which is served as water resource.

Abstract:Wave fields in Lake Taihu are simulated using the wave model SWAN through inputting the actual uniform wind field data.The results show that SWAN model can simulate the wave generation and propagation of Lake Taihu well and is suitable for Lake Taihu.The study also found that the absolute wave frequency is mainly concentrated in the high frequency 0.45-1.00 Hz by analyzing the wave spectrum in Lake Taihu,and there is a high consistency between the wind and waves.On the condition of the same wind speed,the time for wave growing into stable wave is different by regions.The peak absolute wave frequency in the central lake is between 0.342 Hz and 0.585 Hz when it becomes steady,while in the bay area and narrow area around Xishan Island, between 0.447 Hz and 0.765 Hz.On the condition of the same region,with the increase of wind speed,time for wave getting stable reduces and the peak absolute wave frequency moves toward the low frequency.The peak absolute wave frequency in the central lake is no less than 0.340 Hz,and in the bay area and narrow area around Xishan Island,no less than 0.447 Hz.In addition,the change of wind direction has a greater impact on the shape of the wave spectrum in the bay area and narrow area around Xishan Island.

Abstract:Based on daily rainfall and temperature datasets of 127 stations in Lake Poyang catchment during the period of 1960-2007,the climatic drought which was classified into slight drought,heavy drought and extreme drought by using Z index was studied in this paper.The results show that the frequency of drought in the south part of Lake Poyang area is less than that in the north part and the strength of drought in the south part is stronger than that in the north part.The slight drought mainly occurred from July to December,while the heavy drought and extreme drought mainly occurred from January to June.The range and strength of the drought have been increased since 2000 year,especially in 2003,2004 and 2007.The slight drought appeared in most months of 2003 with extensive area and heavy strength.The heavy and extreme drought with small area appeared in most months of 2003,except in March-April and June-July.The area and strength of slight drought were small in most months of 2004,but the heavy and extreme drought with extensive area and heavy strength appeared in March and June.The slight drought in July,October and November of 2007 occurred in extensive area,but heavy and extreme drought in May occurred in more than 80% area of Lake Poyang catchment.

Abstract:Satellite data in different resolutions were used to study thermal environment characters of water body type,Miyun Reservoir, typical urban water bodies and their impacts on the environment around Beijing.The research of different land-use types using MODIS land surface temperature product indicated that at average seasonal time scale water body type of Beijing had temperature-decreasing effect during the daytime,while it had temperature-increasing effect in the night,of autumn and winter,and had temperature-decreasing effect in the night of spring and summer.The analysis of Miyun reservoir using NOAA/AVHRR data showed that it had cold lake effect in the daytime and warm lake effect in the night in summer.On no-freezing condition in winter, Miyun Reservoir had warm lake effect during the day and night.But on freezing condition it had cold lake effect during the day and had no warm or cold island effect during the night.The monitoring results of typical urban water bodies in Beijing using FY-3A/ MERSI,NOAA/AVHRR and Landsat-TM data indicated that water bodies of urban had no heat island effect and the larger area water bodies had strong cold island effect.The analysis of land surface temperature of buildings within 500 meters to typical urban water bodies and Temple of Heaven Park,respectively,indicated that water bodies had lower temperature than the green space of Temple of Heaven Park.Average ground surface temperature of buildings decrease by 1.2,0.6 and 0.4℃ with the distance away from water bodies less than 100 m,100-200 m and 200-300 m,respectively.Green space of Temple of Heaven Park had cooling effect only within 100 m distance with the surface temperature decreased by 0.4℃.The results showed that satellite data could be effectively used to monitor thermal environment of these water bodies,and large area of water bodies were important sources of slowing down urban heat island effect.The maximum distance of cooling effect of water bodies on building around was 300 m in the urban areas of Beijing.

Abstract:Along with the high speed development of economy and society in the developed area in China,the quantity of water pollution emissions increased sharply to a degree well beyond the regional water environmental capacity.The water environment has been deteriorated continuously and becomes a restrict factor to regional development.Taking the basins as a basic spatial unit,this paper discussed both sides of supply ability and demand conditions of water environmental capacity comprehensively,and proposed a method of total index allocation of water environmental capacity include regionalization technique and vector space model.Moreover, taking Wuxi City as an example,this paper proposed multi-scene configuration program of water environmental capacity.First,Gini coefficient method was used to measure the fairness of different programs.Then optimization of different programs was carried out,and the scientificity and operability of allocation scheme were enhanced.As a whole,the central city and northeast region had been allocated more water environmental capacity quantity than the upriver of Lake Taihu and the region along the Wangyu River.The results provide a scientific basis for harmonizing the relationship between regional industrial development and water environment, and policies-making of differentiated industrial access.

Abstract:Benthic Integrity Biotic Index (B-IBI) was used to evaluate the health of inflow rivers in Lake Dianchi of Yunnan Province, China.Macroinvertebrate assemblages were collected from 38 sampling sites in Lake Dianchi,including 9 sites that were undisturbed or less disturbed and 29 sites that were disturbed in wet season of July-Aug.2009 and dry season of Jan.-Feb.2010.The range of index value distribution,spearman correlation and judgment ability were analyzed for the 19 biological parameters,including Shannon-Wiener index;total number of taxa;total density;taxa numbers of Crustacea+Mollusca,Hirudinea,and Mollusca taxa;percentage of Crustacea+Mollusca,Hirudinea,Mollusca,Oligochaeta,Limnodrilushoffmeisteri,Chironomidae,Oligochaeta/Hirudinea,Gatherers,Predator,Omnivore,and Scrapers;percentage of tolerant taxa;and Goodnight index.Ratio scoring method for B-IBI index was used to get a uniform score.By using the each 20 percentiles of B-IBI as a criteria to evaluate the aquatic ecosystem health,the results showed that,health criteria when B-IBI > 1.62,sub-health when 1.03 1.62,good-fair when 0.31-1.03,fair when 0.10-0.31,and poor when B-IBI < 0.10.The B-IBI index was positive correlation to NO-3-N and water temperature,but not significantly correlation to other factors.

Abstract:Before the fishing of Lake Taihu,a mobile hydroacoustic survey was performed in eastern and northern of Lake Taihu in August of 2011,with using BioSonics DT-X scientific echo-sounder (208 kHz).Combining Geographic Information System (GIS) model,then fish size component,spatial distribution and biomass are assessed.The results show that the mean target strength (acoustic reflectivity of target fish) in the surveying lake areas is-51.85 ± 0.02 dB and the mean length is about 6 cm,ranging from 2.35 to 89.33 cm.The fish target strength in different areas is significantly different,which means there is significant difference of fish size,with the minimum mean target strength (-53.94 ± 0.10 dB) in the middle of Dongshan Island and Xishan Island and the maximum mean target strength (-50.27 ± 0.14 dB) in Guangfu Bay.The mean fish density is 2.27 ± 0.57 ind./m³, ranging from 0.43 to 3.90 ind./m³ in all survey areas,where a high fish density occurred in open water zone.Based on the raster data gained from fish distribution GIS model,the total amount of fish mantissa biomass are estimated to be 5.3×10⁹ ind.,in which the fish with target strength lower than-45 dB (length about 13 cm) is 98.49%.The present study provided a preliminary application of the hydroacoustic method and performed in big shallow lake for fish resources investigation.This can break through the limitations of the traditional investigation methods for fish resource assessment on large spatial scales,to a certain extent.The application is still influenced by stormy waves,aquatic plants and speed.

Abstract:In order to investigate the spatial variations of the over-winter algae in different areas of Lake Hongfeng,sediment and water samples were collected monthly at 8 sites over a period of 1 year.Simulation test of dormancy algae recruitment from sediments collected form 4 sites were carried out.The results showed that cyanobacteria were the dominant species in surface water, and the population density of the cyanobacteria was significantly higher than the green algae,diatoms and dinoflagellates.Algal population density evolved seasonally,which was the highest in early autumn and followed by the early spring and summer.Cyanobacteria dominated in over-winter algae in water,followed by diatoms and green algae.The water depth did not affect significantly the population density and composition of the algae in water.Differing from in water,over-winter algae in sediments were mostly diatoms,and only small amount of cyanobacteria were found.Simulation experiments showed that light intensity had a major impact on the algae recruitment,which was also affected by water temperature and sediment algae population density.

Abstract:Submerged macrophyte plays an important role in lake ecosystems.It is not only a primary producer in the food chain, but also plays a major role in lake nutrient accumulation and circulation,thus,having a great influence on the eutrophication process of lakes.This study reports the seed dormancy and germination of three submerged macrophytes (Potamogeton pectinatus, Potamogeton perfoliatus and Myriophyllum verticillatum) in the Yellow River,located in the Hetao irrigation area of the Inner Mongolia.The result shows: Myriophyllum verticillatum seed has a high dormancy rate,but its dormancy is easy to be broken.Various treatments including seed coat scarification,low temperature stratification,applications of KNO₃ and gibberellin can significantly increase the germination percentages.Potamogeton pectinatus seed has a deep dormancy.Low temperature stratification and application of GA can effectively break the seed dormancy,but other treatments had no effect on.Potamogeton perfoliatus seed has a deep dormancy.None of the above mentioned treatments can significantly break its dormancy.

Abstract:To understand the community characteristics of macrozoobenthos and its relationship to environmental factors in Lake Nansi,the species composition,inhabit density,biomass,dominant species,the conditions of aquatic plants and water quality were investigated in June 2010.There were 23 species of macrozoobenthos with the inhabit density of 311.57 ind./m² and biomass of 44.39 g/m².The dominance index was relative high,and the dominant species consist of Chironomus plumosus and Limnodrilus hoffmeisteri which were accounted for 77.45% and 11.39% of the total individuals,respectively.The biomass and coverage of aquatic plants were 1613 g/m² and 33%,and there was no significant correlation between the biomass of aquatic plants and the community characteristics of macrozoobenthos.Lake Nansi was polluted majorly by nitrogen,next by phosphorus and finally by COD_Mn.The community characteristic of macrozoobenthos was not significantly correlated with the community characteristics of aquatic plant and with the water quality.The number of macrofaunal species was significantly negative correlated with the concentration of COD_Mn of water,and the inhabit density of macrozoobenthos was significantly positive correlated with the TLI(Σ) of water in 2010.According to evaluation of Goodnight-Whitley index and TLI(Σ),Lake Nansi has been in the state of clean and mesotropher, but serious pollution in some water areas.

Abstract:Sterile seedlings of Potamogeton crispus were cultured by tissue culture technique,and used as experimental materials.In this study,different concentrations of Ni²⁺(0,0.05,0.10,0.15 and 0.20 mmol/ L) on contents of hydrogen peroxide (H₂O₂),superoxide anion (O₂^.-) and malondialdehyde (MDA),antioxidant defense system and proline metabolism were investigated.The results indicated that (1) Ni²⁺stress triggered the generation of reactive oxygen species (ROS) as evidenced by a substantial accumulation of H₂O₂ and O₂^.-,accompanied by the increased MDA content with the increasing of Ni²⁺concentration;(2) Activities of superoxide dismutase (SOD),peroxides (POD) and catalase (CAT),as well as contents of reduced glutathione (GSH) and non-protein thiols (NP-SH) increased at first and then decreased,while no outstanding changes were observed in ascorbate (AsA) content,and level of phytochelatins (PCs) increased significantly;(3) Analysis of enzyme activities showed that the accumulation of proline induced by Ni²⁺stress is due to the increases of ornithine-δ-aminotransferase (OAT) at 0.05-0.10 mmol/L and pyrroline-5-carboxylate synthetase (P5CS) activity at 0.15-0.20 mmol/ L,respectively,but there was not a statistically significant difference in ProDH activity.Our results demonstrated that Ni²⁺induced the enhancement of reactive oxygen species level,aggravated lipid peroxidation and interfere with intrinsic balance of antioxidant defense system.In addition,proline accumulation is mediated by increased biosynthesis from ornithine at low concentrations (0.05 and 0.10 mmol/L),while glutamate pathway,instead of the ornithine pathway,plays a vital role when exposed to higher concentrations of Ni²⁺.

Abstract:In the present study we evaluated the trophic status of West Lake on basis of investigations from January of 2007 to October of 2010.According to the data associated with species composition,dominant species,density and diversity of rotifers,the relationships between rotifer community structure and eutrophication were evaluated.The result indicated that the water in West Lake had been in a state of eutrophication.The dominant rotifer species were Brachionus angularis and Keratella cochlearis in all 29 species.The amount and diversity of rotifer species are all low.Structures of rotifer community were different in seasons,years and locations.The correlation analysis showed that rotifer density was significantly correlated with water temperature,status of eutrophication, total nitrogen,SD,COD_Mn and pH,respectively.There were significant correlations between Shannon-Wiener diversity index and environmental factors,but only total-nitrogen had obvious correlation with Margalef diversity index.The study showed that there existed an ecological gradient of the community structure of rotifers between intake and outlet,which were influenced by hydrodynamics of water diversion system.

Abstract:During the period of April 2006 to March 2007,secondary production and its dynamics of the dominant species of mayfly community in a second order river (Hujiaxi Stream) of Qingjiang River,Yangtze River Basin were investigated.From the upper to the lower reach of the stream,we sampled at six sites of different habitats quantitatively.The life cycles of the four dominant mayflies, namely Leptophlebia sp.,Electrogena sp.,Indobaetis sp.,and Caenis sp.,were analyzed by the monthly size-class frequency distribution,the cohort and annual production were estimated by size frequency method,and the production dynamics were examined by the method sensu Benke and Wallace (1997).The results show that Leptophlebia sp.,Electrogena sp.,and Indobaetis sp.appear to develop three generations per year,while Caenis sp.completed two generation a year.Their average annual standing stocks were: for Leptophlebia sp.,407 ind./m²,1.00 g/m²;for Electrogena sp.,150 ind./m²,0.37 g/m²;for Indobaetis sp., 232 ind./m²,0.30 g/m²;and for Caenis sp.,91 ind./m²,0.17 g/m²,respectively.The annual production (g/m² (WW)) and the annual P/B ratio of four mayflies were: for Leptophlebia sp.,441.42 g/m² (WW),14.3;for Electrogena sp.,434.88 g/m² (WW),7.6;for Indobaetis sp.,747.21 g/m² (WW),15.0;and for Caenis sp.,40.52 g/m² (WW),7.2.Temporal overlap of secondary production dynamics of the four species,which measured with the proportional similarity index as 0.55,indicates that they utilize similar or same food resources along time dimension.

Abstract:In May 2010, algal bloom dominated by diatom and blue-green algae broke out in Tangpu Reservoir,which is the drinking water resource of Shao Xing,Zhejiang Province.Phytoplankton samples collected from 3 sites(Kuwei,Kuzhong,and Baqian) along the flow direction were investigated.The phytoplankton density ranged between 1.13×108 and 1.56×108 cells/L.The dominant species Achnanthidium catenatum(Bílý et Marvan) is a pennatae diatom,which was first reported from mainland in China.Another dominant species Pseudanabaena limnetica belongs to filamentous cyanobacteria,and their average relative abundances were 65.6% and 28.2%,respectively.Achnanthidium catenatum is the only planktonic species of the genus Achnanthidium showing distinctive girdle view and colonies consisting of a maximum of 3 frustules.Case studied of three different Achnanthidium catenatum blooms indicated that this species was eurythermal and adapted to lower light intensity and phosphorus concentration.Further study should shed more lights on the formation and disappearance mechanisms of this algal bloom.