嗅觉实验配气方法的改进及影响因素研究

配制气体样品是异味测试及相关研究的基础工作，配气稳定性直接影响测试结果准确度。三点比较式臭袋法使用微量进样针量取并转移液体标准物质到3L无臭气袋的传统配气方法。对于异味阈值较小物质或样品浓度处于较低范围时，为了降低取样体积波动对配气精度和稳定性的影响。提出先将标准注入100mL玻璃注射器，充分挥发混匀后再转移部分气体到无臭气袋的两步式配气方法。结果表明，2种配气方法的准确度不存在显著差异，但两步式配气法的配气稳定性明显优于传统方法。此外，研究还发现，常见异味物质在被注人气袋后3min内便能完全挥发并混合均匀。除一些挥发性和吸附性极强的物质外，气袋内的异味物质气体浓度能在配好后20min内基本保持不变。     

Spatio-temporal variations of selected pesticide residues in the Kurose River in Higashi-Hiroshima city,Japan

ABSTRACT

This study investigated spatio-temporal variations of selected pesticide residues in the Kurose River in Higashi-Hiroshima city (Hiroshima Prefecture), Japan. Water samples were collected from the river at seven sites every month for 1 year (March 2016 to February 2017). Pesticide residues were extracted from the samples by a solid phase extraction using Sep Pack C₁₈ cartridges. Once extracted, the samples were analyzed for cyanazine, simetryn, fenarimol, isoprothiolane, and diazinon using a reversed-phase high-performance liquid chromatography ultraviolet visible (HPLC-UV Vis) system. The limits of detection were 3.60, 4.10, 2.80, 6.50, and 7.30 ng L^-1 for cyanazine, simetryn, fenarimol, isoprothiolane, and diazinon, respectively. Good recovery rates (88%–102%), and mean percent relative standard deviation range (1.00%–5.70%) (n = 6) were obtained with a spiking at 0.20 µg L^-1. The maximum concentrations of 282, 391, 60, 1086, and 1194 ng L^-1 were obtained for cyanazine, simetryn, isoprothiolane, fenarimol, and diazinon, respectively. Cyanazine was the most frequently detected pesticide (64% of the samples, n = 84), followed by simetryn (58%), and then diazinon (57%). The highest and lowest pesticide concentrations were measured during the periods May–June, and January–February, respectively. Principal component analysis revealed three principal components in which the pesticides were linked to dissolved organic matter and total suspended solids. The major water quality parameters (electrical conductivity, pH, Na⁺, K⁺, Mg²⁺, Ca²⁺, NH₄⁺, NO₃^?, Cl^?, SO₄^2?, NO₂^?, and temperature) showed no clear trends for these pesticides. The presence of simetryn and isoprothiolane was largely attributed to rice paddy farms, whereas diazinon was associated mostly with vegetable farms and orchards. The diazinon and isoprothiolane patterns were consistent with their use of controlling insects and fungi in the prefecture. The maximum diazinon concentration detected was higher than the human safe level specified by the European Union (100 ng L^-1) in Council Directive 98/83/EC. This is of concern because of the bioconcentration potential of these residues in fish and other marine animals consumed by humans.     

微分脉冲阴极溶出伏安法测定环境水样中的痕量硒

采用微分脉冲阴极溶出法测定环境水样中的痕量硒，以银电极为工作电极，在酸性介质0.06mol.l^-1HCl-0.07mol.l^-1HNO3溶液中于－0.35V(vs SCE)处富集20min，使Se(IV)电沉积为硒化银，然后，以40mV.s^-1的扫速，在碱性介质2．0mol.l^-1NaOH溶液中阴极溶出至－1.2V(vsSCE),硒化银被还原为银的溶出峰电位约为－0.85V(vs SCE),硒的分析校正曲直到40ng.ml^-1仍然成线性，检测下限为11.5pg.ml^-1,相关系为0.9982，灵敏度为10.93uA/ng.ml^-1,20ng.ml^-1的RSD（n=5)为1．26％，检出限（3σ为3.46pg.ml^-1,环境水样中常见离子的存在不干扰痕量硒的测定。     

微波辅助萃取技术及其在环境分析中的应用

微波辅助萃取技术是近年来发展较快的一种新型萃取方法,与传统的提取方式相比,具有省时、节能、简易、高效等优点.文章介绍了微波辅助萃取技术的特点和影响因素,综述了近年来其在环境分析中的应用情况.     

初始氧化温度对浸水长焰煤二次氧化特性的影响机制

为揭示不同初始氧化温度下浸水长焰煤的氧化自燃特性，利用红外光谱和热分析实验手段以及MS数值模拟方法研究其氧化自燃规律，并采用线性拟合的方法阐述自由基变化特性。结合分子键能的变化，分析浸水条件下二次氧化的煤氧链式反应过程。研究结果表明:经过120 ℃预氧化后，浸水风干长焰煤的还原性官能团甲基、亚甲基、羟基均高于原煤，而羰基、羧基低于原煤；与原煤相比，浸水风干后的煤预氧化温度在120 ℃时最大升温速率最高（0.036 9 ℃/s），表现出更强的自燃倾向性；MS模拟优化得出煤中各官能团在预氧化120 ℃时键能变化较大，结合热分析实验，确立预氧化后浸水风干煤体氧化自燃特性机制。     

水系沉积物重金属分析前处理方法

建立了水系沉积物中6种重金属分析的前处理方法,研究了样品粒径、消解前处理对测定结果的影响,对方法适用性作出评价,并对实际样品进行测定。结果表明:通过Hg元素含量的测定,粒径为0.147 mm的沉积物粒径可满足分析要求;采用微波-硝酸-盐酸-氢氟酸消解、ICP-MS法,对5种不同类型沉积物标准样品的6种重金属的测定结果显示,该方法精密度好、准确度高。利用建立的方法测定广西某河流湖库沉积物样品,6种元素测定结果 RSD为1.57%~11.1%,加标回收率大于74.4%。     

液液萃取-高效液相色谱法同时测定水中甲萘威和阿特拉津

用二氯甲烷萃取水中的甲萘威和阿特拉津，经旋转蒸发和氮吹富集浓缩后，采用高效液相色谱二极管阵列检测器在222 nm波长下测定。甲萘威和阿特拉津在0.100 mg/L～5.00 mg/L范围内线性良好，检出限分别为0.031 μg/L和0.027 μg/L，空白水样加标平均回收率为78.5%～91.7%，平行测定3次的RSD＜5%。     

水质分析多样品自动制备系统研究

随着环境监测分析任务日趋繁重,实验室自动化系统越显重要,样品制备是分析自动化的一个重要环节。研制基于空间三维坐标系工作的机器人,用于在水质分析中实现对多样品的自动制备。仪器可对1～3种药液进行自动定量和移置加液,一批次可制备30～208个样品,具有移液误差小、分析精度高、使用灵活方便的特点,是分析检测自动化的理想设备。     

国产脱硝催化剂在国电长源荆州电厂2×300MW机组上的应用

随着新火电厂大气污染物排放标准的出台,NOx排放标准提高,现有的脱硝技术难以满足要求,需要增加后端烟气脱硝处理技术.选择性催化还原法是较成熟的烟气脱硝技术,催化剂是SCR技术的核心.针对国内某催化剂在国电长源荆州电厂的应用情况,详细描述了催化剂的设计选型过程.运行结果表明,该催化剂完全可以满足长源荆州电厂的性能要求,说明国产脱硝催化剂的设计选型、生产以及运行等技术能力已达到要求.     

Polymer and invert emulsifying oil effects upon droplet size spectra of sprays

Abstract

A series of wind tunnel atomization studies were carried out to investigate the effects of polymer and invert suspension oil “drift control adjuvants” upon the droplet size distribution spectra produced by nozzles typically used in aerial and ground based spraying of pesticides. A D8–46 disc and core was used as a typical aerial application nozzle, and an 8003 fan nozzle was used for the ground based sprayers simulation. The droplet size spectra were evaluated in a wind tunnel using a Malvern 2600 laser particle size analyzer immediately upon mixing and at 15 minutes after re‐circulation through a pumping system. The addition of the polymer‐based adjuvants significantly increased the droplet size spectra parameters of the spray cloud, but all the polymer products showed signs of breakdown of their molecular arrangements in the liquid medium, as a result of agitation. The invert suspension oil adjuvant did not change the droplet size spectra markedly, nor did it show signs of breakdown of the internal liquid structure after re‐circulation.