Abstract:A lot of reservoirs are distributed in hilly region in south-east China.These reservoirs are vitally important in providing water resources and should be priorly protected.However,much problem exists in protecting reservoir water quality in the hilly region, including increased development intensity of land resource,unreasonable development approaches and spatial arrangements, serious nitrogen and phosphorus pollution and eutrophication,and lack of advanced monitoring and management systems,etc.Taking Tianmuhu reservoirs as an example,this paper introduced the measures taken to protect Shahe Reservoir (one of Tianmuhu reservoirs) since 2000 and their effect in reservoir treatment,watershed pollutant reduction and integrated watershed management.Based on these analyses,suggestions are made to protect the reservoirs or lakes with good water quality.These suggestions include establishing reservoir management organizations with good departmental coordination,carrying out water quality target management based on lake and reservoir water ecological objectives,controlling non-point source pollution from tea orchards in the hilly area,focusing on restoration of watershed ecological systems,prohibiting land exploitation in upstream hilly area and area close to the lake,determining the red line of ecological protection,defining clearly the prohibit and restrict development types and dimensions, strengthening the monitoring and pre-warning systems of lake,reservoir and watershed,carrying out necessary reservoir treatment, and developing management regulations of lake and reservoir accordingly.After more than ten-year protection practices of Tianmuhu Reservoir,the conflict between watershed development of land resource and reservoir water quality protection was moderated.The lake water quality is changing from rapid deterioration to steady improvement,which provides an effective way for reservoir water environment protection in hilly region of south-east China.

Abstract:Protecting the lake-reservoir water environment plays an important role in the water use for production and lives,maintenance of ecological equilibrium,development of tourism industry.Water quality target management is an effective way to protect the lake-reservoir water.This paper took Shahe Reservoir and its catchment within the Tianmuhu Reservoir area as the study area.By developing a catchment-scale hydrological and water quality model,hydrological flux and water quality in the Shahe Reservoir catchment were simulated,and N and P fluxes into the Tianmuhu Reservoir and their main sources were evaluated.Based on water quality target of the Tianmuhu Reservoir,environmental capacity for N and P pollutions and the amounts required for reduction were calculated.Integrating with the ecological protection goal and suitability assessment of land for development,strategies on zoning reduction of N and P pollutions and land regulation have been explored.The results show that the amounts of N and P flowing into the Shahe Reservoir are 206.01and 3.29 t/a,respectively,with 85.7% and 67.5% from diffuse sources.The difference in output intensity of N and P is significant between various land use types.Land use with the largest output intensity of total nitrogen is tea garden,and then followed in turn by farmland,built-up land,bare land,grassland,abandoned farmland,forests,and wetland.Output intensity of TP is closely related with the land surface coverage,from which bare land is the largest.The rest are built-up land,tea garden,farmland,grassland,abandoned farmland,forests and wetland in turn.From the perspective of N and P transportation processes,the output of TN from the whole catchment is 321.64 t/a,and input amount into the rivers is 255.53 t/a,with 19.4% loss in river channels.Ultimately 206.01 t/a of TN flowed into the Shahe Reservoir.As for TP,the total amount from the catchment is 13.42 t/a.There is 7.90 t/a entering into the rivers,with approximately 58.3% loss in the river channel, and finally 3.29 t/a flowing into the reservoir.The river retention rates of N and P vary between zones,with 34.71% for total nitrogen and 84.31% for total phosphorus,respectively.Based on the results of 2009 on calculated fluxes,the input TN should reduce 32.01 t/a (or decrease 15.50%) and 59.66 t/a (or decrease 29.00%) to meet the criterion of IV and III water quality, respectively.For TP,the input should reduce 0.682 t/a (or decrease 20.70%) and 1.479 t/a (or decrease 44.90%) to meet the criterion of type III and II water quality,respectively.To reduce the diffuse pollution via regulating land use,indexes such as plant coverage,water resource preservation,land slope,land use,N/P contribution from each zone and the distance from the road and villages,should be used to assess the ecological preservation value and exploit applicability,which can help to define the exploit levels,that is forbidden area,restricted area and preserved area.

Abstract:Land use/cover change (LUCC) is closely related to regional sustainable development.It is an important issue in LUCC investigations to analyze the relationship between land use change and its influencing variables on spatial scale,to reveal the change in land use and its spatio-temporal distribution characteristics by developing a simulation model,and to support the future decisionmaking.This study took the Tianmuhu Reservoir watershed,the land use of which has been changed rapidly with the dominant cash crop of tea plantation in upstream of the Lake Taihu basin,as the study area.Interpretation of the high-resolution remote sensing imagery provided the data of tea plantation and other land uses since 2000.Topography and soil data were obtained from the 1:50000 scale national standard relief map and soil sampling with laboratory analysis,respectively.Analyses of the spatial distribution and area change of existing and newly-exploited tea plantation since 2000 revealed that the tea plantation area was in a rapidly increasing trend.The tea plantation area expanded 5 times in the past 11 years and half of those increased in the last 3 years.There was a big difference in the spatial distribution of tea plantation among sub-regions,because of their different natural backgrounds, geographical factors and suitability conditions for tea plantation.The results of Cramer V chi-square test showed that elevation, slope,reservoirs,rivers,villages,roads and the scale of tea garden were the most significant factors for the spatial distribution of tea plantation.The MLP neural network model for the prediction of tea planation was developed through iterations based on the seven significant influencing factors.It was validated using the area of existing tea plantation,the performance of which reached to 84%.Application of the model in predicting the future spatial distribution of tea plantation under current,2000,and the compromised tea-exploitation mode displayed that the area of tea plantation in 2020 will account for 1/4 of the watershed area if it is exploited following the current pace.None of the three scenarios could change the growing trend of tea plantation.Therefore,it is urgent to push the local government to take corresponding strategies and measures to control the increasing area of tea planation and adjust its spatial distributions

Abstract:Based on the 9-year monthly monitoring data,the response of water quality to the economic development activities and the protection countermeasures in catchment and water body of Tianmuhu Reservoir,a meso-eutrophic reservoir with an area of 12 km² located in southeastern of China,was studied.The result showed that the high-density big-head carp (Hypophthalmichthys nobilis) cultivation benefited the algal bloom in the growth season of phytoplankton.Fishery adjustment,with decrease the bighead carp biomass and increase the silver carp (Hypophthalmichthys molitrix) to big-head carp ratio,significantly decreased the peak value of summer phytoplankton biomass.While when the biomass decreased to relative low value,such as 15 mg/L,the control ability of fishery to phytoplankton became weak.The influence of nutrient condition and climate factor became more important to the growth of phytoplankton.Agricultural and tourism development dramatically enhanced the nutrients runoff to the reservoir,especially the tea-farming in the steep slopes strongly increase the spring nitrogen concentration in the reservoir.Low rainfall could significantly decrease the nitrogen concentration in the water on the seasonal scale.This study suggests fishery adjustment,strictly controlling agriculture and tourism development,decreasing the fertilizer application,and expanding the wetland buffer area in the catchment,are the fundamental countermeasures for the water protection in the reservoirs located at southern China like Tianmuhu Reservoir.

Abstract:Dissolved oxygen (DO) is an important indicator of aquatic ecosystem health.The primary production of a lake can be reflected through DO.Study of DO and its vertical distribution is important to understand the eutrophication process of lakes and reservoirs.A three-dimensional hydrodynamic-water quality model (ELCOM-CAEDYM) developed by Center for Water Research of University of Western Australia was applied in order to provide substantial information about vertical distribution of DO at Tianmuhu Reservoir.The simulation duration is from January 1st to December 31st,2011 (365 d).The simulation results of DO,water temperature and total phosphorus (TP) showed good agreement (RMSE<1.8℃,1.8 mg/L and 0.003 mg/L respectively, NSE > 0.7,RE > 10%) with observed data,which indicated that seasonal variation of vertical distribution of dissolved oxygen changed together with thermocline.In winter water column fully mixed at Tianmuhu Reservoir.Thermal stratification started in April and the bottom area became lack of oxygen.Thermocline depth was during 4-10 m below surface with hypoxia (DO<2 mg/L) in the bottom water with an area of 35% of whole bottom area in June.When thermocline disappeared in autumn the vertically-averaged DO concentration started to increase and the water column tended to mix again.DO and TP concentration were influenced by inflows in the riverine zone while lacustrine zone was dominated by significant release resulting from hypoxic events.The vertical distribution pattern of DO induced by thermal stratification in the reservoir could further affect the water environment through algae activities.

Abstract:A large number of forests have been shifting into tea plantation with the continuously promoting of agricultural comprehensive development in the hilly area of Tianmuhu Reservoir watershed,so it is urgent to know how tea plantation expansion influence nitrogen loss.Three experimental natural plots were delineated on tea plantation,secondary pine forest and bamboo forest to study nitrogen loss characteristics via runoff from typical land uses in hilly area of Taihuhu upstream watershed,so as to achieve measured parameters of nitrogen loss via runoff for evaluating the water environmental impact of agricultural comprehensive development in hilly area.TN concentrations in surface runoff of tea plantation,secondary pine forest and bamboo forest were 11.25,2.83 and 3.60 mg/L,respectively,mainly in dissolved form.As to subsurface runoff,they were 27.16,3.59 and 1.06 mg/L,respectively, and were mainly made up of DIN for tea plantation and secondary pine forest,especially as nitrate,while DON for bamboo forest.The plot scale surface runoff coefficients of tea plantation,secondary pine forest and bamboo forest were all less than 0.03, so that subsurface runoff was the major source of runoff.Nitrogen loss was raised heavily with the expansion of tea plantation.The loss rate was 103.08 kg N/(ha·a),which was 7.6 and 23.2 times the loss rate of secondary pine forest and bamboo forest,and 86.7%-99.7% of the total load was lost via subsurface runoff.Subsurface runoff should be paid attention to on prevention and control the nitrogen loss via runoff of tea plantations,and besides reducing fertilizer application,the combination of construction of bamboo buffers at the toe of tea plantation slopes and ponds at the outlet of drainage,so as to prevent and control nitrogen loss via runoff by intercepting nitrogen in situ,is also considerable.

Abstract:To explore the regular pattern of reservoir water quality variation and its influenced factors of Xin'anjiang Reservoir,we comprehensively analyzed the spatial-temporal variations of water quality in Xin'anjiang Reservoir(Lake Qiandao) using the water quality data monitored monthly during 2009-2010 and literature.The results showed that an obvious seasonal variation of transparency was caused by the interaction effects among hydrology,organism,and human production activities cause,total nitrogen,total phosphorus and chlorophyll.Especially in the upstream-Jiekou transect,its seasonal change of each indicator is significantly different.The water quality of the upstream was not same to the downstream water quality obviously with low transparency,high content of nitrogen,phosphorus and chlorophyll.This reflects that exogenous supply and human activities have a primary contribution to water pollution.Thus,the water quality could be improved by controlling the exogenous pollution.The main factor that influences transparency of sensory indicators is the algal biomass,while the factor which controls the algae biomass change is the content of nitrogen and phosphorus.Therefore,strictly controlling the quantity of phytoplankton cells is the key to solve water environmental problems of Xin'anjiang Reservoir.In addition,the economical fishing quantity and inventory of Xin'anjiang Reservoir has certain association with water quality and the inverse correlation was found between the annual fishing quantity and water transparency.Therefore,we should pay more attention to the fisheries management and make a scientific and reasonable fishery culture pattern to keep development of Xin'anjiang Reservoir resources sustainable.

Abstract:The eutrophication evolution process and characteristics of typical small and medium-sized lakes in Lake Taihu basin in the recent 20 years were investigated.Results showed that total nitrogen concentration exhibited a slow downward trend,while total phosphorus concentration showed upward trend during the past 20 years.In response to this,the algae biomass expressed as chlorophyll-a increased gradually and the average transparency (secchi depth) decreased totally.The average chlorophyll-a concentration had increased more than three times since 1991.Standard deviation of chlorophyll-a increased from 1.25 μg/L in 1991 to 19.06 μg/L in 2010,indicating that spatial heterogeneity of eutrophication and algae bloom occurred more frequently.Different types of lakes varied in the eutrophication process.It was not only controlled by nutrient input,but also by its own characteristics of the lake.The calculated Comprehensive Nutrition State Index showed that eutrophication status of Lake Dianshan and Lake Kuncheng were slightly eutrophic but more serious than Lake Shanghu and Lake Kuilei,which were mesotrophic.Designated use and water resource management model of lakes were the important factors in the lake eutrophication.Lake Shanghu and Lake Kuilei,which are under strict management as enclosed drinking water resource area,had stable lower nutrient concentrations.As a typical open lake,Lake Dianshan was classified as middle-eutrophicated TN and TP concentrations of which were increasingly high.As a typical fish-culture type lake,eutrophication problem was becoming more serious due to high-density fish culture in the past 20 years in Lake Changdang,with higher nutrient concentration,higher chlorophyll-a,and lower transparency.

Abstract:Based on the past 50 years data,we made a time-series analysis of the relationships among water quality,hydrology (e.g.,water level fluctuation) and submerged macrophyte succession (e.g.,species composition,biomass and coverage) in Lake Erhai,with the aim to explore the primary driving factors for the succession of submerged macrophyte communities.The results indicated that submerged macrophyte communities had experienced phases as expending,summit and decline.Since the 1980s,the increasing load of external nutrients,deterioration of water quality,heavy algal bloom,simplification of submerged vegetation and decreased grazing pressure of herbival animals had fundamentally impacted on the evolution and distribution of the macrophyte communities in the lake.Meanwhile,the large fluctuation of water levels accelerated the shift from a clear-water state to a turbid one, along with a drastic decline of submerged macrophyte and extinction of some endemic species.Therefore,reducing the external loading of nutrients and a reasonably water level regulation are suggested as priorities for the management and restoration of Lake Erhai ecosystem.

Abstract:Lake Xingkai is suffering from eutrophication and frequent algae blooms.Based on the DELFT-3D model,this study established a set of parameters applicable for the Lake Xingkai ecosystem and simulated the dynamics of water quality and algae.In addition,this paper simulated the change of water quality and algae by setting different control scenarios.The results show that the concentrations of TN,TP and Chl.a rose rapidly in the small Lake Xingkai.With the initial value of 8.96 mg/m³,the Chl.a was increased by 32.37% and 65.51% in 2015 and 2020,respectively,which would lead to serious risk of algae bloom especially in May and August.The simulation result revealed that the concentration of Chl.a changed significantly with the amount of nitrogen input in the small Lake Xingkai.With further nutrient-cutting efforts,the water quality of the small Lake Xingkai could reach type Ⅱ water,the water of the large Lake Xingkai could reach type Ⅲ water.The small Lake Xingkai plays a role of buffer zone for the large Lake Xingkai.Chl.a should be added to the eutrophication control standards to provide early warning for algal bloom.

Abstract:Lake wetlands are important habitats for birds.Wetland birds are considered as the key indicator of lake ecosystems.It is important to understand the relationship between wetland bird diversity and its ecological factors.We investigated 7 major lakes in Anqing floodplain wetlands,middle-lower reaches of the Yangtze River,during July-August,2011.A total of 82 species of birds were found belonging to 14 orders and 35 families,of which resident birds accounted for 32.9%,summer migrators accounted for 45.1%,waterfowls accounted for 34.6%.Carnivore,insectivore and Omnivore made up 30.5%,30.5% and 23.2% of the total birds,respectively.Dominant species in the wetlands were Chlidonias hybridus,Nyticorax nyticorax,Sturnus sericeus, Garrulax perspicillatus,Passer montanus and Hirundo rustica.Among the 7 lakes,Huangda Lake ranked first in bird diversity index and species richness (H=2.123,S=50).Baidang Lake ranked last in bird diversity index and species richness (H=1.918,S=28).The species richness and diversity showed a positive relation to lake size,and a negative relation to disturbance density,respectively.From the view of bird diversity protection,we suggested taking steps to reclaim farmland to lakes and recover the vegetation in the lakes for increasing vegetation cover,wetland size and habitat types.

Abstract:Field work was carried out in Guanting Reservoir on September 5,2012 to study the absorption characteristics of total particulates,phytoplankton pigment,tripton and chromophoric dissolved organic matter (CDOM).The results show that: (1) In autumn,phytoplankton pigment absorption plays a major role in total particulates absorption,thus the absorption of total particulates has the similar characteristics as that of phytoplankton pigment.(2) The absorption coefficients of CDOM and tripton decreased exponentially with wavelength increasing.The slope coefficient of tripton absorption spectral Sd is much smaller than that of other eutrophic waters (eg.Lake Taihu,Lake Dianchi,Lake Chaohu).The slope coefficient of CDOM absorption spectral S_g is similar to Lake Taihu and Lake Chaohu.(3) Significant linear relationship was found between a_ph (440),a_ph (676) and C_Chl.a , but the specific absorption of phytoplankton (a_ph^*) at 440 nm and 675 nm keeps a stable level and has no obvious relationship with C_Chl.a.(4) Significant linear relationship was also found between a_d (440),a_d (676) and C_Chl.a ,which indicates tripton in autumn Guanting Reservoir mainly comes from the degra_dation of phytoplankton.(5) Absorption coefficients of different components from different sites of Guanting Reservoir show four different types of contributions to the total absorption coefficients.In more eutrophic area (Gui Area),phytoplankton dominates water's light absorption,while in less eutrophic area (Zhong Area),particles and CDOM play the same important roles in light absorption.

Abstract:Total suspended matter concentration (C_TSM) is an important parameter for water quality evaluation.In this study,to improve the estimation accuracy of C_TSM in inland type II water,principal component analysis (PCA) was used to reduce the dimensions of hyperspectral data measured in Lake Taihu in April,2009.Different multiple linear regression models of TSM were subsequently constructed using several principle components (PC_s),and the optimal model was determined by comparing the performance of these models with each other.Finally,the applicability of the model to image data of the several current hyperspectral sensors was evaluated.The results show: ① The first 3 PC_s (PC₁ ,PC₂ ,PC₃) could explain the most of TSM variation information and the correlation coefficients between the first 3 PC_s and ln(C_TSM) are 0.728,0.401 and 0.403,respectively;② The optimal model could be developed when the number of PC_s selected to be six.The performance of the model proposed in this study is better than that of the four traditional empirical models;③ Image data of the hyperspectral sensor that has more than 45 bands between 400 and 850 nm could be used to build a stable and accurate model for estimating TSM using PCA.In addition,data from frequently used sensors such as MERIS,HJ1-HSI,Hyperion and CHRIS could be also used to build this type model.

Abstract:In this article,the method of GC/MS with liquid-liquid extraction is adopted to analyze the odor compounds in surface water of Haizhu District in Guangzhou.The 21 water samples were collected from the Pearl River and some lakes and ponds.Referring to the related eutrophication index of water samples detected,the source and distribution of the odor compounds have been researched.The results show that: Geosmin(4.0-69.0 ng/L) and 2-Methylisoborneol(4.1-24.9 ng/L) has the highest content.Among all the surface water in Haizhu District,the stench problem is most severe in Pearl River,followed by lakes and ponds,and the water intake is the least;The content of the odor compounds in the front channel is higher than that in the back one,especially in the section between Aozhou Dock and Guangzhou Bridge.It is found that the content and distribution of the odor compounds are closely related to the extent of water pollution and eutrophication,and the purification of surface water in Haizhu District is still facing a serious situation.In addition,Geosmin and 2-Methylisoborneol are highly toxic to the luminous bacteria in the detection range.

Abstract:We have seasonally investigated the constitution,abundance and diversity of periphytic algae (PA) in Niyang River,the branch of the Yarlung Zangbo River,Tibet from year of 2008 to 2009,and taken quantitative analysis on the spatio-temporal PA characteristics and their relationships with environment factors using multivariate statistics method.The results are listed as follows.Firstly,PA in Niyang River belongs to 6 phyla 30 families 49 genus,among which bacillariophyta is dominant.Secondly,Shannon-Wiener diversity pattern for Niyang River justified the theory of mid-altitude bulge,with higher Shannon-Wiener diversity index in the middle of the river.Thirdly,using Duncan comparison method to judge the difference among sampling sites and seasons for species richness,total abundance and Shannon-Wiener diversity index,there are no significant differences among four sampling sites for three indices mentioned above.In terms of sampling season,there is no significant difference for total abundance.There is significant difference between autumn and winter for species richness,and also significant difference exists between summer,autumn and winter,spring for Shannon-Wiener diversity index.Fourthly,based on the PCA method,total abundance and species richness of periphytic algae descended with the elevation ascending.Even more,based on the CCA method,portion of bacillariophyta and chlorophyta are related with environment factors.Last but not least,we predict the relationship between total PA abundance and environment factors,and the relationship between PA Shannon-Wiener diversity and environment factors based on CART method.The results reveal that PA total abundance from lower elevation of Niyang River is higher than that of higher elevation,and total abundance from higher degree of mineralization of Niyang River is lower than that in lower degree of mineralization.The environment factors that influence the PA quantity should not be applied to PA Shannon-Wiener diversity index.This paper also suggests paying close attention to PA and the environment factors mentioned above owing to their important indication function,in order to warrantee the sustainable development of Niyang River aquatorium ecology.

Abstract:Three waters of different trophic states in the Huaibei and Huainan coal mining subsidence areas,including sites HBNH, PXGQ and PXXQ,were chosen to address their nutrient content,ratio of nitrogen to phosphorus (N: P),and nutrient limitation.Averaged annual concentrations of total phosphorus (TP) in the three sites are 0.056,0.064 and 0.092 mg/L,while the total nitrogen (TN) concentrations are 1.00,0.94 and 2.67 mg/L,respectively.The three studied waters present two trophic levels of "meso-trophic to light eutrophication" and "meso-eutrophciation" with deficiency of phosphorus.Nutrient enrichment bioassays were performed by four groups' experiments.Three treatments were cultured with additions of nitrogen (+N),phosphorus (+P),and nitrogen plus phosphorus (+N+P),with raw water without additions as control.HBNH and PXXQ show features of P limitation,and the other one,PXGQ presents N limitation due to its lower available inorganic nitrogen.Although very low phosphate concentrations,the three sites still have rather high primary production,with their chlorophyll-a concentrations of 13.07 (HBNH),26.95(PXGQ) and 46.25 mg/m³ (PXXQ),which are in accordance with their nutrient states.The results of this research give implication of the importance of P control to these waters in the Huainan and Huaibei coal mining subsidence areas.

Abstract:Phytoplankton is the main primary producer in pelagic water.The biomass of phytoplankton community represents phytoplankton standing stock in water where they are collected.However,the error of different methods for calculating the community biomass is unclear.Based on a data set of phytoplankton from an enclosure experiment with three treatments covering a series of phytoplankton communities,we compared phytoplankton community biomass and phytoplankton species population biomass by four calculating methods which are widely applied in China,i.e.,standard method,fine-group method,coarse-group method and reference method,and then investigated the correlation between chlorophyll-a concentration and the phytoplankton biomass calculated by the four methods.The results showed that the coarse-group method is high-efficiency to calculate phytoplankton biomass and suggested to apply.The positive correlation between phytoplankton biomass and chlorophyll-a is not always significant and can not be largely promoted by improving calculation of phytoplankton biomass.We refer rare species to the species with a population less than 5% of community in biomass,and checked the effect of removal the rare species on the phytoplankton community biomass, and found that ignoring rare species resulted in a significant reduction of total phytoplankton biomass.Therefore,whether the rare species can be ignored depends on the structure of phytoplankton community.

Abstract:To understand the algal community structure,cell abundance and dominant species,Taizi River catchment,Liaohe River basin were investigated four times,from September 2010 to September 2011.Algae,including 8 phyla,120 genera,328 species (including 21 varieties) were identified from 17 sampling sites.Bacillariophyta were the dominant algae and included 36 genera,144 species,accounting for 43.77% of the algae.Chlorophyta,with 49 genera,117 species,accounted for 35.56% of the algae.Cyanophyta,included 22 genera,38 species and accounted for 11.85% of the algae.The cell abundance of algae was higher in summer and autumn,which were 6.80×10⁷ and 3.29×10⁷ cells/L,respectively.However,it was lower in spring with 1.36×10⁷ cells/L.This study also demonstrated that the dominant species of algae in Taizi River catchment were more than five, including Oscillatoria princeps Vauch.,Hormidium flaccidum (Kütz.) Br.and Stigeoclonium subsecundum (Kütz.) Haz.ect.Species Jaccard index of the algae varied from 0.19 to 0.46.Both algal community structure and cell abundance have obvious seasonal variation in Taizi River catchment.

Abstract:In this study,indoors static simulation test was used to investigate the effect of different exposure levels (0.005,0.01, 0.025,0.05 and 0.1 mg/L) of phenanthrene on the growth,free radical,antioxidant defenses and malondialdehyde in Scenedesmus obliquus.Results showed that after 96-h exposure at 0.01 mg/L,the growth of algal cells were significantly inhibited and the signal of free radical (g=2.0033,linewidth is 10.15 mT) increased.The superoxide dismutase,catalase,glutathione-s-transferase activities increased significantly after phenanthrene exposure,demonstrating inducibility mechanisms under stress.The glutathione and malondialdehyde content were significantly elevated after exposure to 0.025 mg/L phenanthrene.In conclusion,S.obliquus is sensitive to phenanthrene,since phenanthrene exposure at low level (even 0.01 mg/L) can induce stress effect.The production of free radical may be an important mechanism involved in the toxicities of phenanthrene on S.obliquus,among which the algae growth is more sensitive to damage index.

Abstract:A Pressure-State-Response (PSR) model was developed to diagnose the sub-regional health of the Lake Wuliangsuhai in the Inner Mongolia.A total of 25 indicators including ecological character indicators,ecological function indicators and social environment indicators were combined to assess the ecosystem health of the lake.Expert Evaluation Method (EEM) and Analytic Hierarchy Process (AHP) were used to identify the weight of each indicator.The Lake Wuliangsuhai was classified into three sub-regions (Ⅰ,Ⅱ and Ⅲ) in consideration of their ecological and environmental characteristics.Results indicate that the lake is staying in a state of alarming or worse quality.The Comprehensive Health Indices (CHI) of three sub-regions are 0.3395,0.3866 and 0.4494,respectively,reflecting obvious regional differences in the lake ecosystem health.The current study may provide useful information for wetland restoration and management.