Lithium extraction from salt lake brines with high magnesium/lithium ratio: a review

Environmental Chemistry Letters - The demand for lithium is growing rapidly with the increase in electric vehicles, batteries and electronic equipments. Lithium can be extracted from brines, yet...     

黄河流域水资源价值的计算与分析

利用经济杠杆的调节作用促使水资源的高效利用，是缓和水资源供需矛盾的有效措施之一。本文以水资源价值理论为基础，从黄河全流域水资源优化配置角度出发，以利用水资源获得最大经济效益为目标，测算了黄河水资源的理论价值，为制定黄河水资源费的征收标准提供科学的理论依据。     

蚯蚓对城镇污泥堆肥过程中微型动物群落演替的影响

采用实验对比和除趋势对应分析（DCA）等方法,以城镇污泥中的微型动物为对象,研究蚯蚓对堆肥过程微型动物群落演替的影响.结果表明,蚯蚓仅影响微型动物群落数量,对演替进程无明显影响.堆肥过程微型动物群落演替可分为3个阶段：第1阶段（0~10 d）,固着类纤毛虫为优势类群阶段,该阶段微型动物变化多受限于环境的改变,蚯蚓影响较小;第2阶段（10~30 d）,固着类纤毛虫和轮虫向肉足虫和线虫为优势类群的过渡阶段,该阶段蚯蚓对线虫数量有一定的限制;第3阶段（30 d后）,肉足虫和线虫为优势类群阶段,该阶段蚯蚓对有壳肉足虫的增长产生了明显的抑制作用.群落多样性指数结果显示,蚯蚓在第1和第2阶段作用不明显,在第3阶段增加了微型动物的多样性和均匀度,减小了优势物种的优势程度.对固着类纤毛虫的同化作用是蚯蚓稳定堆肥环境、促进有机质降解的重要因素.     

基于卫星遥感气溶胶产品评估体系的气溶胶时空分布及变化趋势表征

卫星遥感气溶胶虽然空间覆盖度高,但不同产品数据在准确性和适用性上存在显著差异.为了能够科学定量的衡量各个产品的优劣,选择最合适的气溶胶产品,该研究以数学统计为基础,提出了一种卫星遥感气溶胶产品评估体系,并依此确定了全球6个人口密集地区的最优卫星数据集,在此基础上开展了近10年的（2009—2018）气溶胶时空变化分析.结果表明暗像元算法在植被覆盖度高的地区表现最好,深蓝算法在亮地表的沙漠干旱地区更占优势,而暗像元-深蓝融合算法在土地类型复杂且气溶胶来源多变时得以突出.人口密集的6个区域中,除了区域A和区域B,其它地区的大气污染水平整体偏高.其中,A、B、E的气溶胶负荷呈下降变化,区域F基本不变,其余区域上升变化.评估体系的建立为气溶胶遥感产品的选取提供了新的衡量方法,且该文关于气溶胶时空分布及变化的分析可以为区域性气溶胶研究提供一定的参考价值.     

Adsorption of 17β-estradiol from aqueous solution by raw and direct/pre/post-KOH treated lotus seedpod biochar

Five biochars derived from lotus seedpod(LSP) were applied to examine and compare the adsorption capacity of 17β-estradiol(E2) from aqueous solution.The effect of KOH activation and the order of activation steps on material properties were discussed.The effect of contact time,initial concentration,p H,ionic strength and humic acid on E2 adsorption were investigated in a batch adsorption process.Experimental results demonstrated that the pseudo second-order model fitted the experimental data best and that adsorption equilibrium was reached within 20 hr.The efficiency of E2 removal increased with increasing E2 concentration and decreased with the increase of ionic strength.E2 adsorption on LSP-derived biochar(BCs) was influenced little by humic acid,and slightly affected by the solution p H when its value ranged from 4.0 to 9.0,but considerably affected at p H 10.0.Low environmental temperature is favorable for E2 adsorption.Chemisorption,π–π interactions,monolayer adsorption and electrostatic interaction are the possible adsorption mechanisms.Comparative studies indicated that KOH activation and the order of activation steps had significant impacts on the material.Post-treated biochar exhibited better adsorption capacity for E2 than direct treated,pretreated,and raw LSP biochar.Pyrolyzed biochar at higher temperature improved E2 removal.The excellent performance of BCs in removing E2 suggested that BCs have potential in E2 treatment and that the biochar directly treated by KOH would be a good choice for the treatment of E2 in aqueous solution,with its advantages of good efficiency and simple technology.     

Development of a static test apparatus for evaluating the performance of three PM2.5 separators commonly used in China

PM_(2.5) separator directly affects the accuracy of PM_(2.5) sampling.The specification testing and evaluation for PM_(2.5) separator is particularly important,especially under China's wide variation of terrain and climate.In this study,first a static test apparatus based on polydisperse aerosol was established and calibrated to evaluate the performance of the PM_(2.5) separators.A uniform mixing chamber was developed to make particles mix completely.The aerosol concentration relative standard deviations of three test points at the same horizontal chamber position were less than 0.57%,and the particle size distribution obeyed logarithmic normal distribution with an R~2 of 0.996.The flow rate deviation between the measurement and the set point flow rate agreed to within ± 1.0% in the range of -40 to 50℃.Secondly,the separation,flow and loading characteristics of three cyclone separators(VSCC-A,SCC-A and SCC112) were evaluated using this system.The results showed that the 50% cutoff sizes(D_(50)) of the three cyclones were 2.48,2.47 and 2.44 μm when worked at the manufacturer's recommended flow rates,respectively.The geometric standard deviation(GSD) of the capture efficiency of VSCCA was 1.23,showed a slightly sharper than SCC-A(GSD = 1.27),while the SCC112 did not meet the relevant indicator(GSD = 1.2 ± 0.1) with a GSD = 1.44.The flow rate and loading test had a great effect on D_(50),while the GSD remained almost the same as before.In addition,the maintenance frequency under different air pollution conditions of the cyclones was summarized according to the loading test.     

Chemical characteristics of road dust PM2.5 fraction in oasis cities at the margin of Tarim Basin

In order to understand the compositions characteristics of particulate matter with aerodynamic diameter less than 2.5 μm (PM_2.5) fraction in road dust (RD_2.5) of oasis cities on the edge of Tarim Basin, 30 road dust (RD) samples were collected in Kashi, Cele, and Yutian in the spring, 2018, and RD_2.5 was collected using the resuspension approach. Eight water-soluble ions, 39 trace elements and 8 fractions of carbon-containing species in PM_2.5 were analyzed. Ca²⁺ and Ca were the most abundant ions and elements in RD_2.5 (7.1% and 9.5%). Cl^- in RD_2.5 was affected not only by attributed to saline-alkali soils in oasis cities of the Tarim Basin and dust from Taklimakan Desert but also by human activities. Moreover, the organic carbon/elemental carbon (OC/EC) ratio indicated that carbon components in RD_2.5 in Cele town mainly come from fossil fuel combustion, while those in Yutian and Kashi mainly come from biomass combustion. It is noteworthy that high Ca in RD_2.5 was seriously affected by anthropogenic emissions, and high Na and K contents in RD_2.5 could be derived from soil and desert dust. It was estimated that Cd, Tl, Sn and Cr were emitted from anthropogenic emissions using the enrichment factor. The coefficients of divergence (COD) result indicated that the influence of local emission on road dust emission is greater than that of long-distance transmission. This study is the first time to comprehensively analyze the chemical characteristics of road dust in oasis cities, and the results provides the sources of road dust at the margin of Tarim Basin.     

生态调控后贵州花溪水库浮游植物群落结构的变化特征及影响因素

为了解生态调控后花溪水库浮游植物功能群变化特征与环境因子的关系,基于浮游植物功能群、NMDS（非度量多维尺度分析）、RDA（冗余分析）、Pearson相关性分析方法,于2017年3月-2018年3月逐月对浮游植物群落结构与水环境指标进行采样分析.结果表明:①生态调控前,花溪水库共鉴定浮游植物4门18种,共归类出10个功能群,且功能群H1占绝对优势,其代表藻种为水华束丝藻（Aphanizomenon flosaquae）;生态调控后,共鉴定浮游植物6门66种,共归类出20个功能群,主要优势功能群为B/Lo,其代表藻种为小环藻（Cyclotella sp.）和多甲藻（Peridinium sp.）.②生态调控后,花溪水库优势功能群结构发生了变化,其变化特征为B/Lo（春季）→D/B/Lo/X2/N/P（夏季）→D/B/Lo/N（秋季）→D/MP/B/Lo/W1/W2（冬季）.功能群B的生物量在春季达到峰值（3 056.3 μg/L）,与其对低营养环境有良好的耐受性有关;功能群Lo的生物量在秋季达到峰值（2 900.9 μg/L）,与组成功能群Lo的甲藻特性有关.③RDA结果表明,生态调控前影响浮游植物生长的环境因子为SD（透明度）、ρ（DIN）（DIN为无机氮）;生态调控后影响浮游植物生长的环境因子为WT（水温）、ρ（DO）、ρ（DIN）.研究显示,生态调控后花溪水库功能群结构发生了明显变化,影响功能群变化的主要环境因子为WT和ρ（DO）.