水西沉积物对苯酚的吸附特性研究

解水西湖沉积物的环境化学意义及其在水体自净中的作用。以水西湖沉积物为研究对象,探讨其对苯酚的吸附特性,并系统考察了pH值、温度、振荡时间等因素对其吸附特性的影响。结果表明,当pH值为2.25、反应温度为26.1℃、吸附时间为4 h、沉积物投加量为1.0 g、苯酚溶液初始浓度为160 mg/L时,苯酚的去除率高达18.34%,平衡吸附量为1.1 mg/g。苯酚在水西湖沉积物上的吸附行为可以较好的用Freundlish型吸附等温式来描述。强酸性(pH<6.0)条件下,水西湖沉积物对苯酚具有较大的吸附容量和吸附强度。

The Two Main Mechanisms of Glacier Lake Outburst Flood in Tibet,China

With the global warming,the disasters of Glacier Lake Outburst Flood(GLOF) have taken place frequently in Tibet in recent years and attracted more and more attention.A systematic survey was conducted on the 19 GLOFs in Tibet to study their two main mechanisms.Investigations indicated that all the events occurred in end-moraine lakes,and the outburst occurred partially and instantly.And the breach had the shape of an arc or a trapezoid in overflow outburst and its top width was 3-5 times more than the height.The two main mechanisms of GLOFs in Tibetan end-moraine Lake were overflow and piping,and the overflow mechanism caused by iceberg collapse was dominated in most cases.A formula was proposed to calculate the critical thickness of iceberg tongue that determines the collapse.Granular analysis of the moraine materials revealed that seepage deformation is crucial in the outburst process.Finally,we conducted a case study of the Guangxiecuo Lake to show its possible process of outburst and estimated the peak discharge of the resulted flood.

Phytoplankton Community Dynamics in West Lake After Drawing Water from the Qiantang River

Seventeen phytoplankton dominant species of 218 taxa were found to have contributed to more than 80% of the biomass after analysis of the January, 1955 to December, 1996 phytoplankton population at five stations in West Lake after Qiantang River water had been drawn into the lake for a decade. The seasonal fluctuations were obvious; the maximum cell density of 90.91×10 7-93.58×10 7 cells/L and biomass of 57.41-58.61 mg/L occurred mainly in summer of 1996,largely as a result of the development of Lyngbya contorta, Merismopedia tenuissima, Oscillatoria limnetica, Spirulina laxissima and Scenedesmus quadricauda, etc. at Stations 2 and 4. At Station 1 located near the inlet for drawing water from the Qiantang River, the species number, cell density, biomass, chlorophyll a concentration and physico-chemical parameters (except for total nitrogen) were obviously greater than those at the other four stations, also greater than the corresponding parameters before the drawing of water from the Qiantang River into the lake. Compared with the results of study on the phytoplankton community in 1980 before the drawing of Qiantang River into the lake, the species number and the total individual density were increased, the dominant species changed somewhat, the biomass was decreased. The water quality was improved (especially at Station 1) after the drawing of river water into the lake. Based on criteria for evaluating trophic status, the biological and chemical indicators such as species composition and dominant species, and other parameters such as annual mean value cell densities (36.06×10 7-51.27×10 7 cells/L), biomass (29.03-39.74 mg/L), chl a concentrations (41.29-67.67μg/L), total nitrigen (1.72-2.89 mg/L), total phosphorus (0.12-0.16 mg/L) obtained at Stations 2, 3, 4 and 5, showed that West Lake is still at eutrophic lake.

A Modified DRASTIC Approach to Shallow Groundwater Vulnerability in the West Lake Watershed in Hangzhou, China

The quality of shallow groundwater in the West Lake watershed wasinvestigated form March to July 2000. Integrating with BlacklandGRASS GIS system, the DRASTIC model was used to compile the ground-water vulnerability map. A land use factor was added to the DRASTICmodel and the modified model (LDRASTIC0 increased the accuracy ofprediction form 26.9/100 to 51.3/100. The vulnerability map showedthat the lowly, moderately and highly susceptible area predictedoccupied about 11.6/100, 70.9/100 and 17.5/100 of the wholewatershed, respectively. Compared with the observed values of nitrateand electric conductivity, the LDRASTIC index improved the Pearsoncorrelation coefficients form -0.010 to 0.237 and 0.380 to 0.503;Both the improved coefficients were significant at the 0.01 level.The modified DRASTIC analysis showed a Great potential as a screeningtool for policy decision-making in groundwater management.

Quantity and Quality of Water in the River LermamLake Chapala Watershed, Mexico

Water overexploitation in the Lerma-Chapala Watershed, located in central Mexico, is linked to the development of a strong federal hydrocracy with the mission to capture as much water as possible in order to satisfy social and political demands through the construction of dams and irrigation systems. The reduction in freshwater quantity and the deterioration of water quality are the outcome of industrial inflows, agriculture and urban untreated wastewater. This study has been leaded to determine hydrological, water quality, seed bioassays and the lake fisheries＇ decreases throughout its historical tendencies （1980-2004） in relation to changes in water levels. Hydrological data and water samples for chemical analysis, inorganic nutrients and seed bioassay, were taken from 10 sites alongside the river and two sites from Lake Chapala in years 2005 and 2009, the WQINsF （National Sanitation Foundation Water Quality Index） was estimated. The dissolved oxygen along the river was from anoxic （0.4） to 7 mg/L and the lake had 6.75 mg/L to 7.36 mg/L; the river had highest nutrients variations, Ntot and Ptot 1 mg/L to 〉 10 mg/L. The lake had few physicochemical variations and the lowest nutrient concentrations; WQINsF （water quality index） in the river-lake system showed very bad-bad quality and contamination in river, bad quality-light contamination in lake. Seed bioassays showed inhibition of root elongation and declining fisheries when low water levels were presented. Chapala Lake had better physicochemical and limnological conditions because of the wind action and water column mixing; in contrast the river, high hidrological variations caused by water administration in middle basin.