Abstract:The effect of algal bloom control and water quality improvement using modified local soil/sand induced ecological restoration technology (MLS-IER) was studied in an enclosure in Meiliang Bay in the northern Lake Taihu from October 2010 to September 2011. Lab experiments were used to study the mechanism of long-term water quality improvement including resuspension and internal loads control at water-sediment interfaces. Field monitoring results indicated that, TN, NO₃^--N, NH₄⁺-N, TP and PO₄^3--P were reduced by 66%, 57%, 60%, 93%, 92% and 98%, respectively, 30 min after treatment using MLS; and the average concentrations were reduced by 39.83%, 48.53%, 52.30%, 18.75% and 60.00%, respectively, within the following 11 months compared to the control area. The resuspension experiment showed that the anti-resuspension ability of modified soil and sand increased by a factor of 3 and 5 compared to unmodified soil. The sediment-water incubation experiment showed that algae flocculation followed by capping with MLS remarkably increased the ORP and DO at the sediment-water interface, which reversed the source of sediment-water flux of TP and TN into a sink and remarkably reduced the flux of PO₄^3--P and NH₄⁺-N from sediment to water column. The results suggested that, after nutrients were quickly removed from the water by flocculating the algal blooms, it is possible to physically reduce the resuspension of the algae flocs and chemically block the release of nutrients from the sediment by MLS capping. The sustainable water quality improvement and reduction of algal bloom recruitment can be achieved when the buried algae banks are decomposed and absorbed by the restoration of submerged vegetations in shallow waters, which is triggered by the MLS-IER technology.

Abstract:Species sensitivity distributions (SSD) method was used to assess the acute ecological risk of four commonly-used organophosphorus pesticides (diazinon, parathion, fenitrothion and malathion) to freshwater organisms. The acute toxicity data (LC₅₀) were collected from ECOTOX database and SSD curves were fitted based on BurrⅢ function. The acute ecological risks of the organophosphorus pesticides and the sensitivity of vertebrate and invertebrate (including fish, crustaceans, insects and spiders) to these pesticides were compared by the hazardous concentrations for 5% of the species (HC5) and the potential affected fraction (PAF). The joint ecological risks of the organophosphorus pesticides in the Yellow River, Jiulongjiang River, and Wuxiaochuan River were also analyzed. The following results were obtained:1) by comparing the HC5 and PAF values, the toxicities and ecological risks of the organophosphorus pesticides to invertebrates were significantly higher than those to vertebrates, and the largest toxicities and ecological risks were found to crustaceans, while the minimum to fish. 2) It was found by comparing the SSD curves that, in case of the log-transformed concentration less than 3.5 μg/L, the ecological risks of four organophosphorus pesticides to invertebrates were significantly higher than those to vertebrates; on the contrary, in case of the log-transformed concentration larger than 4.5 μg/L, those to vertebrates were higher. 3) In the vast majority of exposure concentrations, invertebrates were more sensitive to the organophosphate pesticides than vertebrates. Under lower exposure concentrations, crustaceans were more sensitive to the organophosphate pesticides; while, under higher exposure concentrations, insects and spiders were more sensitive. 4) The PAFs and multisubstance PAFs(msPAFs) of parathion and malathion to the freshwater organisms in the Yangtze River, Jiulongjiang River, and Wuxiaochuan River were less than 0.5%, which imply that their ecological risks were very low.

Abstract:The total length of littoral zone of Lake Taihu is about 405 km, and more than 73% of which is surrounded by dike, other part is closed to hill. Therefore it is a typical dike-type littoral zone. According to different land forms, the littoral zone of Lake Taihu is classified as dike-type, hill-type and estuary-type. Based on the condition of hydrology and wetland area, the diketype is classified as 3 sub-types, namely, permanent-wetland-dike-type, intermittent-wetland-dike-type and non-wetland-diketype. The hill-type is classified as 2 sub-types, namely, wetland-hill-type and non-wetland-hill type. That means total 6 sub-types of littoral zones are defined in Lake Taihu. According to the above classification, several ecological restoration modes and their diagrams are proposed, which adopt different measures, from ecological conservation, ecological restoration to ecological reconstruction. The present research may have some implications for the ecological restoration of other lake littoral zones.

Abstract:The enrichment of nitrogen and phosphorus in soil depends on the soil nitrogen and phosphorus budget of different land use types, which can also influence the strength of nitrogen and phosphorus loss. Understanding this process can help us to know its regional environment effect of different land use types. The study area is Lake Tianmu Basin, located in the hilly area of Lake Taihu upper-river basin. We calculated the soil nitrogen and phosphorus budget of different land use types by questionnaire, experimental analysis of soil and biomass, literature investigation and soil apparent balance model, and chose four land use types, including tea garden, paddy fields, masson pine and bamboo forest. We made a systematic analysis of the import and export elements of nitrogen and phosphorus. The import elements included fertilizer, atmospheric deposition, the straw returned to field or dry branches and leaves, biological nitrogen fixation and manure. The export elements included plant absorption, ammonia volatilization and denitrifying. The above analysis can reveal the water environmental effect of mainly land use types in hilly area of Lake Taihu upper-river basin by comparing with the soil nitrogen and phosphorus content. Results show that the order of soil nitrogen and phosphorus surplus are tea garden, paddy field, masson pine and bamboo forest, with the values of 648.6, 248.9, 115.5, 53.6 kgN/(hm²·a) and 319.9, 29.7, 1.2, -3.4 kgP/(hm²·a), respectively. The nitrogen and phosphorus utilization efficiency of bamboo forest is the highest, while tea garden is the lowest one, only 15.0% and 3.1%. The soil nitrogen surplus and nitrogen content failed to present a consistent relationship although the soil phosphorus surplus and phosphorus content is similar. This shows that the bamboo forest is more advantageous to the water environmental protection than masson pine, and the tea garden is worse to the water environmental protection than paddy fields.

Abstract:Aiming to the problem of the difficult central treatment on rural domestic sewage, a new approach of biofilm aggrandizement on the treatment of rural domestic sewage on the spots in surface flow constructed wetland was raised and corresponding experiments were carried out. Results showed that water purification ability improved obviously after setting the biofilm carrier in surface flow constructed wetland, especially under higher pollution load (COD_Cr:657.27 mg/L, TN:26.27 mg/L, TP:8.66 mg/L, SS:276 mg/L). The removal rates of TN, TP and COD_Cr were increased by 21.64%, 16.24% and 19.12%, respectively. In addition, the setting of the biofilm carrier had little impacts on the wetland system itself through the detection of microorganisms in wetland. The improvement of the water purification ability mainly resulted from the increase of the microorganism on the biomass carrier. This new method could improve the wetland efficacy without expanding wetland areas, which provides a promising solution for rural domestic sewage.

Abstract:The optimum of carbon sources adding location and the effects of adding to different locations(surface, the upper, middle and lower layers) on the removal efficiency of nitrogen, phosphorus and COD_Cr were investigated in small-scale vertical flow constructed wetlands. The results showed that the removal efficiency of the nitrate nitrogen in the lower layer was lower than that in the middle layer, and the most suitable location for carbon sources supplement was the middle and lower layer of the vertical flow constructed wetlands. Among the systems with carbon sources added, the one which added the carbon sources to the surface layer exhibited the highest removal efficiency of COD_Cr, and the concentration of COD_Cr of the effluent of each system were lower than the influent, not causing the concentration of COD_Cr increasing of the effluent of the systems. Adding carbon sources can significantly improve the removal efficiency of nitrogen and phosphorus. The system which added the carbon sources to the lower layer showed the highest removal efficiency of total nitrogen. The system which added the carbon sources to the surface layer showed significant ammoxidation, and the concentration of ammonia nitrogen of the effluent was highest. The removal efficiency of each system showed no significant difference in the removal efficiency of nitrite and nitrate nitrogen, and all showed great removal efficiency of nitrate nitrogen. The system which added the carbon sources to the lower layer showed the most complete nitrification, and the removal efficiency of total phosphorus was also significantly better than that of other systems. Adding carbon sources to the lower layer of the vertical flow constructed wetland can achieve the effect of simultaneous removal of nitrogen and phosphorus.

Abstract:Spatial distribution of nitrogen in the soil, biomass and nitrogen contents of Typha latifolia community, Polygonum hydropiper community, Juncus effuses community and Phragmites communis community in the Zhucao river mouth wetland into Daxi Reservoir in Liyang City, Jiangsu Province were studied. Significant differences of aboveground biomass, belowground biomass and nitrogen contents of four plants were found. Soil loss on ignition (LOI), total nitrogen (TN) and nitrate nitrogen (NO₃^--N) concentrations showed decreasing trend on the vertical distribution with increasing depth. Ammonium nitrogen (NH₄⁺-N) concentrations in soil profiles decreased first, and then increased. Soil nitrogen concentrations of the four plant communities were different, but most of them were higher than the control, and organic nitrogen was the main form, indicating that the wetland had a certain nitrogen storage capacity and different plant communities affected the distribution of nitrogen. The correlations between LOI and total nitrogen, ammonium nitrogen, nitrate nitrogen were significant. Inorganic nitrogen constituted only a small proportion (1.41%), which indicated that the nitrogen mainly presented in the organic form. However, there was nearly no correlation between biomass, nitrogen contents of four types of plant and nitrogen concentrations of each soil layer. This indicated that soil nitrogen contents were affected not only by the form of plant growth, but also by the plant root zone environment, the number and activity of microorganisms.

Abstract:Seasonal dynamics and spatial distributions of chlorophyll-a concentration and its relationship to environmental factors in Lake Erhai from May 2010 to April 2011 were investigated. Results showed that the seasonal dynamics of chlorophyll-a concentration in Lake Erhai were obvious, ranging from 4.11 to 24.30 μg/L and with the annual mean value 10.4 ± 6.5 μg/L. The minimum and maximum of chlorophyll-a concentration appeared in March and September, respectively. The chlorophyll-a concentrations were much higher in summer and autumn while relatively lower in winter and spring. Spatially, chlorophyll-a concentrations were the highest in the southern zones of the lake, followed by the northern and the middle zones. Pearson correlations and principal component analysis suggested that the chlorophyll-a concentration has negative correlation with transparency in different zones of Lake Erhai, while has positive correlation with water temperature. The chlorophyll-a concentration was correlated significantly with total nitrogen in the northern and southern zones of Lake Erhai, while correlated with total phosphorus in southern zones. Based on the modified Carlson trophic state index, the comprehensive TSI was 50.6 in Lake Erhai, indicating a mesotrophic state.

Abstract:Concentration of chlorophyll-a (Chl. a), total phosphorus (TP), total nitrogen and water temperature are the four main driving factors resulting in eutrophication in Meiliang Bay, Lake Taihu. Based on the observation data in the period of 1992 -2010, the temporal pattern characteristics of the four factors in different temporal scales were analyzed respectively using wavelet analysis. Results showed that the temporal patterns of the four factors were obvious in the inter-annual and inter-decadal scales and the primary periods were different, but the real parts of wavelet coefficients of Chl. a and TP were consistent. The distributions and the periodic oscillation were analyzed and it was predicted that the eutrophication condition in Meiliang Bay would keep stable in the future 3-5 years. This method will provide reliable scientific evidence to the management of Lake Taihu.

Abstract:Lake Dianchi is a famous plateau freshwater lake, whose basin is the most active area of socio-economy in Yunnan Province. Through systematic investigation socio-economic development and changes of aquatic environment in 1988-2009, the main influencing factors of such changes were analyzed. Results showed that the annual increasing rate of population, GDP, and urbanization in the Lake Dianchi Basin reached 3.3%, 18%, 17% in recent 20 years, respectively; With the rapid development in socioeconomy, total water consumptions and pollutant emissions continuously increased. At the same time, the water quality in main rivers deteriorated significantly, with the percentage of rivers with water quality type-Ⅴ increased by nearly 4 times. The water quality of inner (Lake Caohai) and outside of the lake were degraded to worse than type-Ⅴ. The deterioration of water quality and lake eutrophication have become important water environmental problems in Lake Dianchi, which are difficult to be relieved in the short term. In the basis, we proposed some measures and recommendations to improve the water environment in the basin, including optimizing industrial structures, construction of sewage treatment systems, wastewater reclamation, rural environmental protection, ecological compensation mechanism and so on.

Abstract:With the deterioration of ecological environment, the location choices of manufacturing industries are becoming more restricted by environmental capacity and government regulation. This paper highlights the impact of environmental regulation on the location choices of manufacturing industries. Wuxi City is selected as a case since it has faced most intensive conflicts between economic development and environmental protection. Based on the neo-classical location choice theory of manufacturing industries and the existing literature on the evolution mechanism of industrial locations, this paper established a new analytic framework of combining both traditional factors and environmental regulation factors so as to explain the location choices of pollution-intensified enterprises in Wuxi City from 1998 to 2008. We further applied a GIS-based spatial autoregressive model to explore the effects of environmental regulation on the distribution of manufacturing industries in Wuxi City. Results showed that during 1998 and 2003 the location choices of pollution intensified enterprises were mainly affected by the traditional factors such as transportation accessibility, land prices and the development zone planning, while the influence of environmental regulation factors was not significant. However, from 2003 to 2008, the environmental regulation emphasizing water quality and channels of clean water supply showed a strong effect on the location choices of pollution enterprises. This result suggested that environmental regulation has become an important factor affecting the locations of pollution intensified manufacturing. This study provides an important reference not only for the policies of industrial structure adjustment but also for the theories about the coordinated development of urban economy and environment.

Abstract:To clarify polycyclic aromatic hydrocarbons (PAHs) contamination characteristics in Lake Chaohu, 27 surface sediment samples from different locations in the lake were collected in 2010. Concentrations of 14 kinds of PAHs measured by HPLC were identified as priority pollutants by the US EPA. The total concentration of PAHs ranged from 116.0 to 2832.2 ng/g dry weight, with an average value of 898.9 ± 791.0 ng/g dry weight. The profiles of PAHs showed that 5- and 6-ring PAHs were predominant, which accounted for 32%-58% of the total, respectively. A good correlation between TOC content and the total PAHs concentration was observed. Based on Anthracene/(Anthracene + Phenanthrene) and Benzo (a) anthracene/(Benzo (a) anthracene + Chrysene) ratios, PAHs originated largely from the high-temperature pyrolytic process. Risk assessment indicated that the sediment in Nanfei River was most likely to pose biological impairment, while low toxicological risk of PAHs was found in other sampling sites.

Abstract:Sterile seedlings of Potamogeton crispus L. were cultured by tissue culture technique. They were exposed to 0, 5, 10, 15, 20 μmol/L Hg²⁺ respectively for 3 days and analyzed with reference to its toxic impact on total chloroplyll content, chloroplyll autofluorescence, the ATPase activity and mineral nutrition absorption under lab conditions. Results revealed that with increasing Hg²⁺ concentration, the intensity of chloroplyll autofluorescence and chlorophyll decreased gradually. The content of soluble protein increased under 5 μmol/L Hg²⁺ stress, and then followed by a decline in the present of higher concentration of Hg²⁺, which was the same as the change of Ca²⁺ Mg²⁺-ATPase activity. Na⁺ K⁺-ATPase also decreased with the rise of Hg²⁺ concentration. The absorption of Na, K, Ca, Mg was affected under Hg²⁺ stress. It was concluded that photo system and normal physiological metabolism were disordered.

Abstract:Concentrations of pigments could reflect the dominant phyla of algae. Investigations of algae in eutrophic lakes revealed that Chl. b, Chl. c and phycobilin (PC) are the critical pigments of chlorophyta, bacilliariphyta and cyanophyta, respectively. In this study, partial least square (PLS) regress was used on the retrieval of Chl. a, Chl. b, Chl. c and PC through absorption spectral of phytoplankton. Retrieve of Chl. a was based on the data collected in situ during 2011. Retrieve of Chl. b and Chl. c was based on the data collected in situ in March, since there is no significant dominant phyla of algae in spring. Result shows that PLS is a more effective method than the original least square regress and could be of help for remote sensing of multi-pigments and the distribution of main algae in eutrophic lakes.

Abstract:Chromophoric dissolved organic matter (CDOM) mainly absorbs light in water which may influence the nature water color in lakes. Its absorption and photochemical degradation products play an important role in the primary productivity of water and carbon cycle. In Lake Taihu, a total of 333 sites were sampled in October 2004, October 2008, April 2010 and January and March 2011 to analyze the contribution of CDOM to total light absorption and estimate [a_CDOM/a_t](412) from remote sensing. It was found that the average of [a_CDOM/a_t](412) exhibited highly temporal variations during the five cruises. The maximum (0.369) was determined in 2011, comparing with all samples in Lake Taihu (0.295 ± 0.139). The minimum average of [a_CDOM/a_t] (412) in the dataset 201004 was 0.236 ± 0.108, varing from 0.046 to 0.455. No significant difference was observed in the dataset 200410 and 200810. The mean of[a_CDOM/a_t](412) in Zhushan Bay was higher than that in both whole Lake Taihu and Meiliang Bay. For Meiliang Bay, it had almost the same value with the whole lake. A multi-band algorithm was adopted to estimate the [a_CDOM/a_t](412) by remote sensing and acceptable results were detected (n=333, RMSE=34.60%). Suspended sediments and pigments had an important impact on determination of [a_CDOM/a_t](412) from remote sensing. It was underestimated because of pigments and overestimated as the suspended sediments in water and the latter was worse. The results also showed that the CDOM and detritus optically dominate the water color in Lake Taihu.

Abstract:Lake Nansi consists of four lakes:the Nanyang, Dushan, Zhaoyang and Weishan Lake. It is a lake in the line of the Eastern Route Project (ERP) of the South-to-North Water Diversion Project (NSBD). After the project supply water in 2013, the water quality of Lake Nansi will be affected significantly. Based on the existing theories and methods, a three-dimensional hydraulic control and water quality model of the lake is presented. The model is developed under the Environmental Fluid Dynamics Code (EFDC) model. It was calibrated and verified to hydrodynamic and water quality data, using two sets of observed data from October 1 to December 31, 2006 and January 1 to June 30, 2007, respectively. The observed data including water surface elevation, water temperature, chemical oxygen demand, dissolved oxygen and ammonia nitrogen from five stations is used as forcing for simulations. The model results show that temporal and spatial patterns for hydrodynamic and water quality components are consistent with observed data in the reservoir. Because the direction of the water supply and natural flow is converse, the Lake Nansi is divided into the upper-lake and the lower-lake by Erji dam in the Lake Zhaoyang. Two scenarios of whole supplying water term of the lake were simulated using the model. By the analysis of the variations of the hydraulic control and water quality of the upper-lake and lower-lake, This paper proposed three advices of the ERP operation, which can help the project to give full benefits and improve the water quality.

Abstract:In studies of lake-atmosphere interactions, the fluxes of momentum, water vapor and heat (latent and sensible heat) are parameterized as being proportional to the differences in wind, humidity and air temperature between the water surface and a reference height above the surface. The proportionality or transfer coefficients are often assumed to follow the gradient observation above lake surface or the parameterizations established for the marine atmospheric surface layer. Optimization against the eddy covariance and micrometeorology measurements made over a large shallow freshwater lake (Lake Taihu) shows that the transfer coefficients of momentum (C_D10N), water (C_E10N) and heat (C_H10N) were C_D10N=1.52×10^-3, C_E10N=0.82×10^-3 and C_H10N=1.02×10^-3, respectively. These values are in good agreement with the values derived from the eddy covariance measurement in other inland lakes. Comparison with oceanographic parameterizations suggests that lake surfaces were aerodynamically rougher than open oceans under similar wind conditions, which may due to the shallow depth of the lake, and that these parameterizations can bias the annual lake evaporation estimate by as much as 40% higher. Our results also suggest that these coefficients can be regarded as constants independent of stability and wind speed. Sensitivity analysis indicated that the mean error between calculation and observation of latent heat flux (LE) decreased 0.5 W/m², that of sensible heat flux (H) decreased 0.4 W/m², and no difference between friction velocity (u*) calculation and observation if stability correction was considered since around 83% of data were in neutral condition. If the effect of wind was considered, the mean error between calculation and observation decreased 0.004 m/s for u*, increased 1.3 W/m² for LE, and negligible for H. This study can provide reference for the research on lake-atmosphere interaction.

Abstract:Chlorophyll-a concentration of Huguangyan Maar Lake sediments were determined by diffuse reflectance spectroscopy. Through comparison with TOC, Sr intensity and magnetic susceptibility we concluded that chlorophyll-a can be taken as a reliable proxy of primary production, higher chlorophyll-a absorption reflects stronger monsoon intensity and higher precipitation, and vice versa. Holocene environment evolution at Zhanjiang area reconstructed by chlorophyll-a, TOC, Sr intensity and magnetic susceptibility of Huguangyan Maar Lake sediments demonstrated that the monsoon intensity in Zhanjiang area was strong in the early Holocene and declined dramatically since 6000 a BP. Holocene climate evolutional pattern at Zhanjiang area is similar with many other records from the monsoonal areas of the North hemisphere and summer isolation at 30°N, implying that solar isolation is the driving force of millennial-scale Holocene monsoon evolution at Zhanjiang area. However, monsoonal evolution lags behind solar isolation by about 2200 a. Monsoon strengthen demonstrated by chlorophyll-a declined significantly since 6000 a BP. Nonetheless, all the other records display gradual weakening process. Negative feedback of vegetation-atmosphere induced by solar isolation might have caused quick droughty trend, on the other hand, dilution effect led by increased sedimentary rate may amplify declining trend of chlorophyll-a around 6000 a BP. Sedimentary environment since 3600 a BP could be impacted by human activities.

Abstract:Nitrogen isotopic technique was used to study the nitrate pollution of four inflowing rivers of Lake Chaohu in different seasons. Our results showed that River Shiwulihe was the most polluted river, while River Shuangqiaohe as the least polluted one. Nitrogen Stable isotopic values demonstrat that nitrate sources differ in various seasons for those four rivers. The dominate pollution sources of nitrate for River Shiwulihe and River Nanfeihe are human sewage and industry discharge. In the case of River Paihe, nitrate is mainly derived from industry discharge in winter, which is originated from agriculture and rainfall in spring and summer, respectively. For River Shuangqiaohe, nitrate contamination is mainly caused by agriculture in winter and spring, but is influenced by rainfall in summer. In addition, our results imply that ammonium is the main nitrogen pollution compound in those four rivers, and δ¹⁵ NH₄⁺ value should be detected for the identification of ammonium sources in further study.

Abstract:Based on object-oriented method, six ETM + satellite images of the year 2002 were interpreted and analyzed to study the seasonal change of the lakes in Tengery Desert. Result indicates that lake level changed sharply over the years. That is, both the amount and the area of the lakes in Tengery Desert reached their summits in summer (June), while the lowest amount and level in winter. This phenomenon differs from that of the Badain Jaran Desert, in which the lakes have their high level during winter. The difference to some extent explained the different replenishment patterns between the lakes in two deserts:lakes in Tengery Desert would be recharged by precipitation and adjoining ground water, but those in Badain Jaran Desert would be highly affected by longdistant ground water.

Abstract:Lakes located in the monsoon marginal zone in North China are sensitive to climate change. Lake Wulagaigaobi is an enclosed lake in Inner Mongolia of China, which is in the semiarid and sub-humid ecotone on the northeast margin of the Inner Mongolia Plateau. In this paper, a sediment profile of 405 cm deep was chose. The measured data of the sediment in AMS¹⁴C and OSL age revealed that the sediment profile was deposited since 51.9 ka BP. Combined with chronological data and the analyses of sedimentary characteristics, including grain-size distribution, grain-size frequency, grain-size parameters, and trace elements, the evolutionary process and features of the lake environment were reconstructed during the past 50000 years. Results showed that there were four climate periods:51.9-44.1 ka BP (405-343 cm), cold and dry period, a lower lake-level; 44.1-28.5 ka BP (343-130 cm), warm and wet period, the lake-level fluctuated; 28.5-11.38 ka BP (130-35 cm), cold and dry period; 11.38 ka BP-today (35-0 cm), warm and wet period.

Abstract:Ecological deterioration of lakes is a worldwide phenomenon. The ultimate objective for their restoration is to achieve 'good ecological quality', which is with no, or only very minor, anthropogenic alterations to lake environment. Since current lake ecosystems are developed from the origin over a long time-scale, palaeoecological techniques based on lake sediments have several advantages in establishing lake reference condition. This review introduced the definition, methods, features and application of reference condition in lake restoration. Finally, some potential research themes were proposed for the application of palaeoecological techniques in the restoration of Chinese waterbodies.