Variability of sedimentary phosphorus fractions in the western and Sandusky basins of Lake Erie

Surface sediments and three sediment cores from the western basin and one sediment core from the Sandusky basin were analyzed to document spatial and temporal changes in five phosphorus fractions and total phosphorus (TP). The areal distributions of the bioavailable fractions NaCl-Pi, NaBD-Pi, and NaOH-Pi and the refractory organic fraction Res-P were broadly consistent and contrasted with those of the detrital fraction HCl-Pi which showed that high concentrations occurred mostly in high-energy littoral zones and low concentrations largely in profundal depositional areas. The contrasting distributions were induced by interactions among tributary inputs, wave action, circulation, and biogeochemical cycling and transfer in the basin. As revealed by the Sandusky basin sediment record, the detrital fraction HCl-Pi was dominant (70% of TP) during European settlement and decreased rapidly by 28.0% in the early 1910s due largely to impoundments of the Maumee and Sandusky Rivers. While HCl-Pi has ever since remained relatively constant, NaCl-Pi, NaBD-Pi, and NaOH-Pi increased significantly between 1950 and 1970 in the two basins. However, the post-regulation sediment records differed considerably among these coring sites. There was a marked increase of TP in two cores, corresponding to recent return of eutrophication and massive harmful algal blooms but contrasting with a relatively constant, low loading into the lake. This signified the role of internal loading as derived partialy from legacy pollution. Furthermore, NaCl-Pi has increased progressively throughout all the records. We conclude that the increased levels of NaCl-Pi in surface sediments may have altered the internal loading and contributed to the resurgences of harmful algal blooms in Lake Erie.     

初始运行工况对水泵水轮机飞逸过渡过程水力特性的影响

飞逸过渡过程是抽水蓄能电站可能发生的一类事故工况。此过程中水泵水轮机的转速、流量和压力大幅改变,转轮流态极易恶化,可能引发剧烈压力脉动和转轮受力失衡。水泵水轮机初始运行工况是飞逸过程的重要控制因素之一,但其对此过程中机组水力特性的影响尚不明确。本文用一维管道与三维水泵水轮机耦合的数值模拟研究了某模型抽水蓄能系统中水泵水轮机从两个不同初始运行工况发生飞逸过程时水力特性的差别。结果表明,相对于流动条件较好的额定工况,由流动条件较差的部分负荷工况开始的飞逸过程更容易引起水泵水轮机运行轨迹的剧烈跳动以及流道压力脉动和转轮径向水推力的幅值突增,原因是在此过程中更易形成转轮流动失稳,机理是过渡过程中的瞬时流态保留有相应初始工况的部分流动特征,即瞬时流态的演化存在迟滞效应。因此,在当前不断拓宽抽水蓄能机组运行范围以满足电网容量调节需求的背景下,应充分考虑初始运行工况对可能发生的飞逸过程的影响。     

细菌对红黏土抗剪强度的影响

为了探究土壤原生细菌对红黏土强度的影响,通过对红黏土中天然赋存的原生细菌进行富集培养,并在红黏土重塑试样中添加培养后的细菌菌液,通过土工试验和电镜试验分析红黏土物理力学性质和微观结构的变化。结果表明:随着细菌的掺入,三轴试样的破坏峰值和压缩模量都有所提高,并且随时间的增长,呈现先增大后减小的趋势;同时从电镜图像上来看,细菌的掺入使得红黏土中粉粒含量有所增加,相应的黏粒含量下降。研究结果可为进一步研究单一的细菌种类对红黏土物理力学性质和微观结构的影响提供参考。     

Characteristics of cationic Red X-GRL adsorption by diatomite tailings

As secondary mineral resources, diatomite tailings(DT) got from the Linjiang region of China were prepared and characterized by SEM, XRF and XRD. Mono-factor experiments were carried out to investigate the effects of the operation factor, including contact time, adsorbent concentration, initial p H value of the dye solutions, adsorption temperature and initial concentration of cationic Red X-GRL(X-GRL) on the adsorption of X-GRL. The adsorption kinetics, isotherms, thermodynamics and mechanisms for X-GRL were also studied. It was efficient for DT to adsorb X-GRL from aqueous solutions, and it was even discovered to have higher adsorptivity for X-GRL than diatomite concentrate(DC) in our previous test. The adsorption processes fit very well with the pseudo-second-order model and the Langmuir isotherm equation. In addition, various thermodynamic parameters, such as standard Gibbs free energy(ΔG°), standard enthalpy(ΔH°) and standard entropy(ΔS°) have been calculated. From thermodynamic studies, it was seen that the adsorption was spontaneous and endothermic. The main driving forces of the physical adsorption on DT are electrostatic attraction. The reason why DT showed higher adsorptivity for X-GRL than DC was that there were more clay mineral particles within, which has a remarkable ability of dye adsorption due to its high surface area. DT as a cheap absorbent for X-GRL removal would replace or partially replace the activated carbon.     

给水球墨铸铁管腐蚀特性及腐蚀对水质的影响

为研究给水球墨铸铁管腐蚀特性及腐蚀对水质的影响,以球墨铸铁管为主体制作三电极反应体系,以微生物为控制变量利用电化学工作站测定球墨铸铁管电化学腐蚀参数,同时分析腐蚀体系内水体水质变化.结果表明:非灭菌组自腐蚀电位66 d均值-0.515 V,自腐蚀电流密度均值7.61×10-4m A/cm~2,期间水质迅速变差,总铁质量浓度3 d后超标,色度和浊度最终分别达72、115 NTU.灭菌组自腐蚀电位66 d均值-0.471 V,自腐蚀电流密度均值5.26×10-4m A/cm~2,腐蚀强度较灭菌组稍缓,但水体最终变成"黄水".没有或失去防腐涂层而暴露于水体中的给水球墨铸铁管初期极易发生以电化学腐蚀为主的综合性腐蚀,严重影响水质.     

Electrochemical behavior of magnolol on FeWO<Subscript>4</Subscript> nanoflower modified carbon paste electrode

In order to establish a simple, sensitive, and fast reliable detection method to determine the magnolol, FeWO₄ nanoflower was synthesised through a solvothermal technique and FeWO₄ nanoflower modified carbon paste electrode (CPE) was developed. The voltammetric behavior of magnolol on the modified electrodes was studied using cyclic voltammetry (CV), linear sweep voltammetry (LSV), and differential pulse voltammetry (DPV). The experimental results showed that the modified electrode remarkably enhanced the electrochemical response of the magnolol and exhibited a wide linear range for determination of the magnolol from 1.0×10^-7 to 1.0×10^-4 mol/L with a low detection limit of 5.0×10^-8 mol/L.     

面向水流系统功能的多维度水资源承载力评价指标体系

在简述水资源承载力研究进展的基础上,基于系统结构与功能的相互关系和水资源系统的演变特征,从水资源系统自然演化、生态服务和社会服务三大功能推演出水资源系统的水量、水质、水生栖息环境和连通性四维结构,并以此对水资源承载力进行表征。基于对水资源承载主体、客体及承载过程的分析,以水资源承载支撑力、压力和调控力描述承载过程,建立了基于承载过程的"水量-水质-水生栖息环境-连通性"四维指标体系,该指标体系可用于不同流域或区域多维水资源承载力评价。     

锦屏一级拱坝黏弹性工作性态反演分析

针对锦屏一级拱坝历年1 880 m高水位稳定期坝体向下游侧位移持续增大的异常变形性态,基于现场位移监测数据和坝体混凝土徐变试验数据,对该拱坝当前运行性态进行了反演分析。结果表明:坝体目前处于黏弹性工作状态,监测发现的短期趋势性变形是由水压荷载作用下黏弹性滞后变形效应和年周期环境温降效应所共同引起。混凝土黏弹性力学参数之间具有较好的线性关系,基于弹性水压分量反演得到的坝体混凝土弹性模量实际是瞬时弹性模量与延迟弹性模量的等效值,对于锦屏一级拱坝,该反演值为35.5 GPa,与前期反演值和试验值较为接近;而基于黏弹性水压分量反演得到的广义Kelvin模型中瞬时弹性模量、2延迟弹性模量和2黏滞系数分别为47.3 GPa、189.4 GPa、132.3 GPa、383.8 GPa·d和20 574.6 GPa·d。建议今后对锦屏一级拱坝建立变形监控模型时,应在HST模型中引入黏弹性滞后水压分量。     

投影寻踪方法在水资源承载力评价与预测中的应用

为解决区域水资源承载力综合评价中指标数据高维、非线性的问题,构建基于最大信息熵原理的投影寻踪水资源承载力评价方法,将该方法应用于2015年安徽省16个地级市水资源承载力的空间分布评价中;最后对2005—2015年安徽省全省水资源承载力进行动态评价,将该评价结果与灰色GM(1,1)模型结合,对2018—2020年安徽省区域水资源承载状况进行预测。结果表明:2015年,安徽省水资源承载空间分布状况整体表现为皖南地区优于皖中地区,皖中地区优于皖北地区;2005—2015年期间,全省水资源承载力虽基本处于临界超载状态,但年际间承载状况逐年好转。预测结果表明,2018—2020年全省水资源承载力保持良好的发展态势,总体向可载趋势发展。     

Removal of hexavalent chromium in aquatic solutions by pomelo peel

This study investigated the removal of hexavalent chromium(Cr(VI)) in aqueous solutions using pomelo peel(PP) and FeCl_3-modified pomelo peel(FPP) as novel biomass adsorbents.Batch adsorption experiments were performed to evaluate the effects of pH,time,temperature,initial concentration,and adsorbent dose on Cr(VI) removal by PP and FPP.The results show that the maximum adsorption capacity of Cr(VI)was 21.55 mg/g for FPP and 0.57 mg/g for PP at a pH of 2.0 and a temperature of 40℃.The surface shape,microstructure,and chemical composition of FPP were analyzed with scanning electron microscopy(SEM),Fourier transform infrared spectroscopy(FTIR),and energy dispersive spectroscopy(EDS),and compared with those of PP.The results show that the adsorption performance of FPP was much better than that of PP,indicating that FPP can be an alternative high-efficiency adsorbent for Cr(VI) removal.