加速溶剂萃取(ASE)-固相萃取(SPE)-高效液相色谱法(HPLC)测定土壤中青霉素钠

建立了一种加速溶剂萃取(ASE)-固相萃取(SPE)-高效液相色谱(HPLC)测定土壤中青霉素钠的简单、快速的方法.样品以超纯水为提取溶剂,50℃提取温度为ASE提取条件参数;HLB型固相萃取柱富集净化:6.0mL 5%甲醇淋洗、4.0mL乙腈-甲醇(1∶1)洗脱;高效液相色谱-紫外检测器(HPLC-PDA)测定,检测波长λ=191.1nm,柱温30℃,流动相为乙腈-0.1%甲酸/水(1∶1),采用等梯度洗脱程序,取得较好的检测分离效果.对0.5、2.0、8.0mg·kg-1等3个不同添加浓度水平的青霉素钠平均加标回收率范围为73.1%—89.7%,回收率相对标准偏差RSD范围为1.1%—2.9%(n=5),检出限可达235.0μg·L-1.结果表明,该方法操作简单,快速,准确度和精密度均符合质量控制要求,能够满足环境土壤样本中痕量青霉素钠检测分析的要求.     

珍贵树种土沉香生长环境的土壤特性与营养特性分析

对我国野生土沉香4个主要分布区的土壤特性及自身营养特性进行了分析研究。结果表明,不同分布区的同一土层的土壤物理性质有明显的差异（P〈0.05）。海南临高分布区各层土壤容重最小,总空隙度、自然含水量毛管持水量比较高;海南屯昌分布区各层的土壤容重最大,总空隙度较低;广东东莞分布区与广东陆河分布区各层土壤松紧度比较适宜,透水性,通气性,持水能力比较协调。各分布区土壤均呈酸性,其有机质含量和营养元素含量偏低。土壤有效Mn、有效B均处于较低水平,有效Fe的含量均高于临界值;海南屯昌分布区土壤中有效Cu的含量极低,其余3分布区则均高于临界值;除海南临高分布区有效Zn的含量高于临界值,其他3个分布区均低于临界值;海南屯昌分布区土壤有效S含量稍低于临界值,为中等水平,广东陆河分布区高于临界值处于较高水平,广东东莞分布区为临界值的2.76倍,而海南临高分布区则高达临界值的7.31倍,均处于极高水平。野生土沉香叶片各营养元素之间的相关性总体不明显。     

Competitive adsorption and desorption of copper and lead in some soil of North China

The competitive adsorption and desorption of Pb(II) and Cu(II) ions in the soil of three sites in North China were investigated using single and binary metal solutions with 0.01 mol·L^-1 CaCl₂ as background electrolyte. The desorption isotherms of Pb(II) and Cu(II) were similar to the adsorption isotherms, which can be fitted well by Freundlich equation (R₂>0.96). The soil in the three sites had greater sorption capacities for Pb(II) than Cu(II), which was affected strongly by the soil characteristics. In the binary metal solution containing 1∶1 molar ratio of Pb(II) and Cu(II), the total amount of Pb(II) and Cu(II) adsorption was affected by the simultaneous presence of the two metal ions, indicating the existence of adsorption competition between the two metal ions. Fourier transform infrared (FT-IR) spectroscopy was used to investigate the interaction between soil and metal ions, and the results revealed that the carboxyl and hydroxyl groups in the soil were the main binding sites of metal ions.     

Seed terminal velocity, wind turbulence, and demography drive the spread of an invasive tree in an analytical model

Little is known about the relative importance of mechanistic drivers of plant spread, particularly when long-distance dispersal (LDD) events occur. Most methods to date approach LDD phenomenologically, and all mechanistic models, with one exception, have been implemented through simulation. Furthermore, the few recent mechanistically derived spread models have examined the relative role of different dispersal parameters using simulations, and a formal analytical approach has not yet been implemented. Here we incorporate an analytical mechanistic wind dispersal model (WALD) into a demographic matrix model within an analytical integrodifference equation spread model. We carry out analytical perturbation analysis on the combined model to determine the relative effects of dispersal and demographic traits and wind statistics on the spread of an invasive tree. Models are parameterized using data collected in situ and tested using independent data on historical spread. Predicted spread rates and direction match well the two historical phases of observed spread. Seed terminal velocity has the greatest potential influence on spread rate, and three wind properties (turbulence coefficient, mean horizontal wind speed, and standard deviation of vertical wind speed) are also important. Fecundity has marginal importance for spread rate, but juvenile survival and establishment are consistently important. This coupled empirical/theoretical framework enables prediction of plant spread rate and direction using fundamental dispersal and demographic parameters and identifies the traits and environmental conditions that facilitate spread. The development of an analytical perturbation analysis for a mechanistic spread model will enable multispecies comparative studies to be easily implemented in the future.     

美国饮用水水源地保护经验及其对我国的启示

新冠肺炎疫情对公众健康造成了极大威胁。针对疫情可能造成的水污染问题,各地生态环境部门均全力加强城市和农村饮用水水源地水质监测预警工作,突出了当前形势下饮用水水源保护工作的重要性。为实现安全饮用水目标,美国在法制体系、组织结构、饮用水水源地风险评估和保护计划等方面积累了丰富的经验,为我国应对疫情、实现饮用水安全保障提供了诸多启示。美国实践经验表明,饮用水水源地保护应建立从废水排放控制到水源地风险防范的全方位、一体化管理体系;完善"从水源地到水龙头"的监测与应急体系;构建分工明确、权责清晰的制度体系;完善公众参与和信息公开,形成多方共治的良好局面。基于美国水源地保护经验,本文研究提出如下建议:加强全国饮用水水源地风险评估,严防医疗污水和城镇生活污水向水源地排放;加强水源地水质监测和预警,提升监测预警水平并制定备用水源等应急响应计划;强化地方政府对水源地的统一监管职能,明确水源地管理部门和水源地水厂的职责分工,加强组织协调和联防联控;完善公众参与和信息公开,增强公众环保意识和"主人翁"意识。     

我国沿海地区港口竞争力综合评价

港口是连接世界生产、分配、交换和消费的中心环节.随着世界经济及国际贸易的快速发展,港口在一国区域经济和对外贸易中的地位日益突出,港口之间竞争日益加剧,因此对港口竞争力的研究意义重大.将熵权法与TOPSIS法相结合,对我国沿海地区的港口竞争力进行综合评价和比较分析.结果表明,广东、浙江、上海、山东港口竞争力普遍较强,辽宁、福建、江苏、天津港口竞争力中等,河北、海南、广西港口竞争力相对较弱,提出了相应的对策建议.     

Perverse Incentive Structure and Policy Implementation Gap in China's Local Environmental Politics

The obvious paradox within China's environmental politics is the big gap between the central government's policy and its implementation outcomes at local levels. Despite concerns about implementation at the local level, much about the role of central governments in China's local environmental politics is still poorly understood. This article examines how the incentive structure set by the central authorities affects the policy implementation gap at the local level. Drawing on fieldwork and document analysis, this article argues that the incentives set by the central government regarding environmental policy implementation at local levels are perversely structured, meaning that the central government provides much more incentive for local governments' non-implementation or poor implementation of its environmental policies than it provides for full implementation. The central government's failure to encourage—politically, financially, as well as morally—local government officials to appropriately implement environmental policies can partly explain the production of the policy implementation gap at the local level. This implementation gap cannot be overcome by efforts at the local level unless the central government takes significant measures to address the perverse incentive structure embedded in the overall structure of China's local environmental politics.     

Type 0092丝状菌污泥微膨胀在短程硝化中的实现

利用Type 0092丝状菌不易引发污泥恶性膨胀的特点,本实验采用实际生活污水,以SBR反应器接种短程硝化污泥,考察了短程硝化状态下启动Type 0092丝状菌污泥微膨胀的特性,研究了系统启动与维持期间的污泥沉降性能、亚硝酸盐积累率(NAR)、污染物去除特性以及污泥菌群结构变化情况.结果表明控制DO为0. 3～0. 8 mg·L~(-1),F/M(以COD/MLSS计)=0. 24 kg·(kg·d)~(-1),按照交替缺氧/好氧模式运行(单周期3次,缺氧∶好氧=20 min∶60 min),能够启动Type 0092丝状菌污泥微膨胀与短程硝化耦合,系统SVI值维持在180 m L·g~(-1)左右,NAR一直维持在99%左右,COD和TN去除率能够分别提高约13%和5%,相较于传统全程硝化非微膨胀状态曝气量能节省约62. 5%.当交替缺氧/好氧模式变为单周期交替6次,缺氧∶好氧=10 min∶30 min,亚硝酸盐氧化菌(NOB)的活性会恢复,使短程硝化被破坏;低溶解氧、交替缺氧/好氧、低负荷是实现Type 0092丝状菌污泥微膨胀的关键因素,当负荷(以COD/MLSS计)大于0. 25 kg·(kg·d)~(-1)时,仅靠低溶解氧和间歇曝气无法维持污泥微膨胀状态.     

温带阔叶红松林中不同树种和倒木对土壤性质的影响

以长白山温带阔叶红松林为研究对象,通过野外采集土壤样品,综合研究老龄树及倒木对周边表层土壤性质的影响。研究结果显示,在本研究样地条件下,不同树种周边的表层土壤性质存在显著性差异,红松（Pinus koraiensis）周边土壤中水溶性有机碳WSOC的质量分数和特征吸光系数SUVA254值都高于紫椴（乃砌amurensis）和水曲柳（Fraxinus mandshurica）,但是土壤水溶性总氮WSTN和交换性无机氮的质量分数却是红松低于紫椴和水曲柳。对倒木影响的森林表层土壤性质的研究结果显示,倒木下方森林表层土壤中WSOC、WSTN以及交换性矿质氮的质量分数都明显地高于林间土壤,说明在小尺度空间区域内,倒木可能是森林表层土壤活性碳、氮库的重要输入源。此外,本研究还利用主成分分析探讨了受树种影响的森林表层土壤不同性质之间的关联性,并对树种和倒木影响周边土壤性质的可能性机制进行分析。     

北京地区秋冬季大气污染特征及成因分析

为了研究近两年北京地区PM2. 5污染特征及成因变化,利用常规观测资料和改进的后向轨迹模型(Traj Stat)对2016～2017年秋冬季大气重污染时段的颗粒物浓度、气象要素和气团传输路径进行了综合分析.结果表明,研究期间北京地区共发生13次持续2 d以上的重污染事件,冬季过程约占61. 5%,且污染程度和持续时间均高于秋季.地面受弱气压场控制、高湿度、静小风以及较低的混合层高度,加之北京三面环山的特殊地势是导致秋冬季静稳型污染频发的重要因素,重污染期间PM2. 5/PM10的平均比值高达0. 86.累积阶段气团主要来自于西北、偏西、西南和东南方向,其中西南和东南路径为典型污染传输通道,轨迹频率为21. 6%.此外,采用WRF-CAMx模型定量估算了2016年12月16～22日典型过程中本地和外来污染源对北京PM2. 5的贡献,结果发现不同气团输送条件下,二者的贡献差异较大.当南部气团输入时,本地贡献会显著下降,以外部区域输送为主导;若气流来自西北方向情况则相反.污染过程期间,本地贡献为16. 5%～69. 3%.