Effects of sediment dredging on water quality and zooplankton community structure in a shallow of eutrophic lake

Effects of suction dredging on water quality and zooplankton community structure in a shallow of eutrophic lake,were evaluated.The results showed that a decreasing trend for levels of phosphorus,organic matter,total suspended solids,Chlorophyll a and Secchi transparency in the water column was found,while levels of water depth,electrical conductivity,total dissolved solids and NO 3--N concentration increased markedly post-dredging.The effects of dredging on dissolved oxygen,pH value and temperature were alm...     

Quantum dots enhance Cu2+-induced hepatic L02 cells toxicity

As a new class of xenogenous nanoparticle,quantum dots (QDs) possess the potential to co-exist with Cu2+ in human liver.The combined toxicity is thus concerned.Considering QDs and Cu2+ are known ROS (reactive oxygen species) inducer,we investigated the combined oxidative stress and corresponding protective strategy using human hepatic L02 cells.The results demonstrated that the presence of a small amount of MPA-CdTe QDs (2 μg/mL) in a Cu2+ solution (2.5-20 μg/mL) resulted in a higher toxicity with up to 8-fold cell viability decrease,which was accompanied by cell morphology changes.The combined toxicity was then confirmed as ROS associated oxidative stress with up to 300% and 35% increase of the intracellular ROS level and glutathione S-transferase (GST) activity,respectively.N-acetylcysteine (NAC) can also provide almost complete protection against the induced toxicity.Therefore,the ROS associated oxidant injury might be responsible for the QDs-Cu2+/Cu2+ induced toxicity and could be balanced through cytoprotective antioxidant enzyme GST.     

Particle properties in granular activated carbon filter during drinking water treatment

The elemental composition and bacteria attached in particles were investigated during granular activated carbon (GAC) filtration.The experimental results showed that trapped influent particles could form new,larger particles on GAC surface.The sloughing of individuals off GAC surface caused an increase in effluent particles in the size range from 5 to 25 μm.The selectivity for element removal in GAC filters caused an increasing proportion of metallic elements in the effluent particles.The distribution of molar ratio indicated a complicated composition for large particles,involving organic and inorganic substances.The organic proportion accounted for 40% of total carbon attached to the particles.Compared with dissolved carbon,there was potential for the formation of trihalomethanes by organic carbon attached to particles,especially for those with size larger than 10 μm.The pure carbon energy spectrum was found only in the GAC effluent and the size distribution of carbon fines was mainly above 10 μm.The larger carbon fines provided more space for bacterial colonization and stronger protection for attached bacteria against disinfection.The residual attached bacteria after chorine disinfection was increased to 10 2-10 3 CFU/mL within 24 hours at 25°C.     

Removal of humic acid from aqueous solution by cetylpyridinium bromide modified zeolite

Natural zeolite was modified by loading cetylpyridinium bromide (CPB) to create more e cient sites for humic acid (HA) adsorption. The natural and CPB modified zeolites were characterized with X-ray di raction, field emission scanning electron microscopy, Fourier transform infrared spectroscopy and elemental analysis. The e ects of various experimental parameters such as contact time, initial HA concentration, solution pH and coexistent Ca2+, upon HA adsorption onto CPB modified zeolites were evaluated. The results showed that natural zeolite had negligible a nity for HA in aqueous solutions, but CPB modified zeolites exhibited high adsorption e ciency for HA. A higher CPB loading on natural zeolites exhibited a larger HA adsorption capacity. Acidic pH and coexistent Ca2+ were proved to be favorable for HA adsorption onto CPB modified zeolite. The kinetic process was well described by pseudo second-order model. The experimental isotherm data fitted well to Langmuir and Sips models. The maximum monolayer adsorption capacity of CPB modified zeolite with surfactant bilayer coverage was found to be 92.0 mg/g.     

Regional crop yield, water consumption and water use efficiency and their responses to climate change in the North China Plain

The North China Plain (NCP) is one of the most important regions for food production in China, with its agricultural system being significantly affected by the undergoing climate change and vulnerable with water stress. In this study, the Vegetation Interface Processes (VIP) model is used to evaluate crop yield, water consumption (ET), and water use efficiency (WUE) of a winter wheat (Triticum aestivum L.)–summer maize (Zea mays L.) double cropping system in the NCP from 1951 to 2006. Their responses to future climate scenarios of 21st century projected by the GCM (HadCM3) with Intergovernmental Panel on Climate Change Special Report on Emission Scenario (IPCC SRES) A2 and B1 emissions are investigated. The results show a rapid enhancement of crop yield in the past 56 years, accompanying with slight increment of ET and noticeable improvement of WUE. There exist spatial patterns of crop yield stemmed mainly from soil quality and irrigation facilities. For climate change impacts, it is found that winter wheat yield will significantly increase with the maximum increment in A2 occurring in 2070s with a value of 19%, whereas the maximum in B1 being 13% in 2060s. Its ET is slightly intensified, which is less than 6%, under both A2 and B1 scenarios, giving rise to the improvement of WUE by 10% and 7% under A2 and B1 scenarios, respectively. Comparatively, summer maize yield will gently decline by 15% for A2 and 12% for B1 scenario, respectively. Its ET is obviously increasing since 2050s with over 10% relative change, leading to a lower WUE with more than 25% relative change under both scenarios in 2090s. Therefore, possible adaptation countermeasures should be developed to mitigate the negative effects of climate change for the sustainable development of agro-ecosystems in the NCP.     

Ca~(2+)与Pb~(2+)相互作用对斑马鱼胚胎毒性效应的影响

为探明Ca2+浓度增加是否会使鱼类早期发育阶段对铅毒性的敏感性升高,以及Ca2+单独减弱铅毒性的浓度范围,选用斑马鱼胚胎作为实验材料,记录在不同的水化学参数条件下,胚胎发育过程中一些具有代表性的毒理学终点,采用相对易于观察且敏感的指标--72 h孵化率进行分析.用Visual MINTEQ2.5.2软件进行溶液中离子的化学形态分析.结果表明,当Ca2+浓度从0.25 mmol/L增加到2.00 mmol/L时,导致了以自由铅离子活度({Pb2+})和溶解态铅总浓度([Pb] T)表示的72 h EC 50的增加(表现为发育延迟),两者之间存在良好的线性关系.通过这一线性关系,可以对Ca2+浓度对铅毒性的影响进行预测.这一结果支持了生物配体模型(BLM)概念的假设,说明在胚胎的表面,铅离子与钙离子可能在传输和毒性作用位点上存在竞争作用.而当Ca2+浓度从2.00 mmol/L增加到4.00 mmol/L时,72 h EC 50 {Pb2+}和72 h EC 50 [Pb] T并没有显著的增加.     

植物-土壤渗滤法对农村生活污水的处理工艺研究

采用植物-土壤渗滤法对农村生活污水进行处理研究,结果表明:体系对BOD5、CODCr、TN、NH4+-N、TP的平均去除率分别为74%、79%、85%、91%、89%,出水达到国家一级排放标准,该工艺在农村生活污水处理中具有广阔的应用前景.     

青藏高原典型高寒草甸区土壤有机碳氮的变异特性

本研究应用地统计学的基本原理与方法(半方差分析)对青藏高原典型高寒草甸区0～10 cm土壤有机碳和全氮空间变异性进行了分析.结果表明,0～10 cm的土壤有机碳和全氮的平均含量分别为11.45 g·kg^-1和1.02 g·kg^-1,平均变异系数分别为0.23和0.21,反映出该植被区土壤肥力较为贫瘠.土壤有机碳和全氮随机因素的变异占总空间异质性变异的比率分别为44.7%和49.9%,变异尺度分别为210.9 m和200.1 m,随机因素的影响主要发生在采样尺度＜10 m的范围之内.在该研究区域上土壤有机碳和全氮均表现出空间自相关因素大于随机因素的变异格局;在空间结构的变异上,由土壤内在属性如土壤矿物质、地形等空间自相关因素和人为因素如放牧及工程施工等对土壤表层的践踏引起的随机因素共同起作用,影响程度呈中等水平.     

西部管道工程HSE一体化绩效管理应用研究

分析了我国管道工程项目HSE绩效管理存在问题,运用绩效管理理论,结合“PMT（业主）＋PMC（监理）＋EPC（施工总承包方）”一体化模式及西部管道工程,阐述了HSE一体化绩效管理体系的建立及应用情况。     

多源数据支持下城市火灾风险评估及规划响应

为探析城市火灾风险的空间格局特征,提出科学的火灾防控体系,以合肥市为研究对象,基于火灾风险兴趣点(POI)数据、NPP/VIIRS夜间灯光影像数据、消防站与道路信息等多源数据,运用SAVEE模型和迭代方程评估城市火灾风险,并引入区位-配置(L-A)模型,从不同目标情境优化消防站点布局。研究表明:火灾高风险区主要集中于合肥市二环以内的建成区,尤其是老城区、合肥西站片区、政务区、科学城和东部新中心等区域;现有48座消防站对研究区内的POI覆盖效果较好,覆盖率为86.76%,而对NPP/VIIRS覆盖效果一般,覆盖率仅为55.94%,覆盖率在合肥市东北部、西北部和南部部分地区仍有不足;基于最大化覆盖模型,规划新增44座消防站,明显提升5 min响应时间的覆盖率,可进一步夯实城市消防安全。