Analysis of herbicide residues by gas chromatography

The extraction and clean‐up, and gas Chromatographic conditions for the detection and determination of herbicides, their metabolites and related compounds are reviewed. The literature material is examined critically in the text and presented in tabular form for quick reference. The section dealing with extraction/clean‐up techniques is sub‐divided with respect to water, soil, plant material, animal, fish and micro‐organisms. Under eight herbicide group headings the important gas Chromatographic parameters such as stationary phase, support phase, column temperature and mode of detection are tabulated. Also tabulated are the application of various detectors to herbicide analyses and limits of detection where information was available. Most commonly used liquid and support phases are listed and their frequency of use given. Different aspects of derivative formation used for the positive identification and quantitation of herbicides are discussed with emphasis on esterification, alkylation and silylation. Other important conversion techniques are outlined, particularly those associated with enhancement of sensitivity e.g. bromination, iodination, dinitrophenylation etc. Efforts that have been made towards general and automated analytical methods are discussed.     

2019年11-12月国内生产安全事故统计分析

统计了2019年11-12月国内发生的各种生产安全事故89起,其中包括交通事故、矿业事故、爆炸事故、火灾、毒物泄漏与中毒和其他事故。统计表明,在89起事故中,交通事故占41.57%,矿业事故占8.99%,爆炸事故占8.99%,火灾占8.99%,毒物泄漏与中毒占4.50%,其他事故占26.97%。89起事故共死亡274人。死亡人数的百分比分别为交通事故40.88%,矿业事故占16.79%,爆炸事故占7.30%,火灾占9.49%,毒物泄漏与中毒占4.74%,其他事故占20.80%。2019年11-12月生产安全事故发生较多的5个省和自治区分别为安徽(9起)、河南(7起)、四川(6起)、广东(6起)和广西(6起);死亡人数较多的5个省分别为云南(31人)、山西(28人)、湖南(24人)、河南(21人)和贵州(21人)。     

基于多元统计的水质动态评价模型研究与应用

给出一种基于多元统计的水质动态评价模型方法,该模型方法以全局主成分分析(GPCA)方法为主,以动态聚类分析、判别分析为辅助方法。再以湟水流域水质断面为例,根据有机污染、无机污染和综合污染等3个方面对这些水质断面1998—2005年水质污染状态进行定量评价和动态分析。研究结果表明:湟水流域水质断面有机污染较为严重,以上3个方面的污染状态逐年严重,综合污染指数均值从1998年的1.63605上升到2005年的2.38624,2001年以后有加速恶化的迹象。     

Modelling cadmium bioaccumulation in Gammarus pulex by using experimental design approach

Recently, although dynamic approaches have been used increasingly to describe metal bioaccumulation in aquatic organisms, the validation of such laboratory-derived modelling is rarely assessed under environmental conditions. The present study aims to evaluate and verify statistical and mathematical models for the bioaccumulation of cadmium (Cd) and to evaluate the suitability of Gammarus pulex as a biomonitor for Cd. To optimise Cd²⁺ ion bioaccumulation conditions a Box–Behnken design was used and whether G. pulex can be used as an estimated tool to assess aquatic quality was investigated. A Box–Behnken experimental design combined with response surface modelling (RSM) was employed for Cd²⁺ bioaccumulation in G. pulex. Independent variables including temperature, contact time and Cd²⁺ ion concentration significance and their interactions were tested using analysis of variance. The selected variables’ optimum values were obtained by solving the quadratic regression model along with by analysing the response surface contour plots. Based on Box–Behnken design, the applied model is significant because model F-value and R² were obtained as 5121.49, 0.9998, respectively. Bioaccumulation of Cd amount was analysed using electrothermal atomic absorption spectrophotometer. The obtained data suggest that G. pulex can be evaluated as Cd biomonitor.     

Assessment of temporal and spatial variations in water quality using multivariate statistical methods： a case study of the Xin＇anjiang River,China

This study evaluated the temporal and spatial variations of water quality data sets for the Xin＇anjiang River through the use of multivariate statistical techniques, including cluster analysis （CA）, discriminant analysis （DA）, correlation analysis, and principal component analysis （PCA）. The water samples, measured by ten parameters, were collected every month for three years （2008-2010） from eight sampling stations located along the river. The hierarchical CA classified the 12 months into three periods （First, Second and Third Period） and the eight sampling sites into three groups （Groups 1, 2 and 3） based on seasonal differences and various pollution levels caused by physicochemical properties and anthropogenic activ- ities. DA identified three significant parameters （tempera- ture, pH and E.coli） to distinguish temporal groups with close to 76% correct assignment. The DA also discovered five parameters （temperature, electricity conductivity, total nitrogen, chemical oxygen demand and total phosphorus） for spatial variation analysis, with 80.56% correct assignment. The non-parametric correlation coefficient （Spear- man R） explained the relationship between the water quality parameters and the basin characteristics, and the GIS made the results visual and direct. The PCA identified four PCs for Groups 1 and 2, and three PCs for Group 3. These PCs captured 68.94%, 67.48% and 70.35% of the total variance of Groups 1, 2 and 3, respectively. Although natural pollution affects the Xin＇anjiang River, the main sources of pollution included agricultural activities, industrial waste, and domestic wastewater.     

2004年11-12月国内安全事故统计分析

统计了2004年11-12月国内发生的各种安全事故457起,包括矿业事故、交通事故、爆炸事故、火灾、毒物泄露和中毒及其他事故.统计表明,在这些事故中,矿业事故最多,占57.11%,平均每天4.3起事故,其次是交通事故(30.20%)、其他事故(5.91%)、爆炸事故(2.84%)、火灾(2.41%)、毒物泄露和中毒(1.53%).457起事故共死亡1 708人,伤1 211人,死亡人数的百分比分别为矿业事故47.95%、交通事故39.87%、其他事故5.97%、爆炸事故2.75%、火灾2.69%、泄露中毒0.76%;受伤人数的百分比分别为交通事故54.75%、矿业事故19.98%、泄露中毒10.07%、爆炸事故8.59%、其他事故5.95%、火灾0.66%.     

2005年5-6月国内安全事故统计分析

统计了2005年5-6月国内发生的各种安全事故486起,包括矿业事故、交通事故、爆炸事故、火灾、毒物泄露和中毒及其他事故.统计表明,在这些事故中,矿业事故最多,占59.47%,平均每天4.7起事故,其次是交通事故(27.98%)、毒物泄露和中毒(3.91%)、爆炸事故(3.70%)、其他事故(3.70%)、火灾(1.23%).486起事故共死亡1366人,伤1 565人,死亡人数的百分比分别为矿业事故40.85%、交通事故40.12%、爆炸事故5.34%、其他事故5.34%、泄露中毒5.20%、火灾3.15%;受伤人数的百分比分别为交通事故35.72%、爆炸事故30.54%、矿业事故23.90%、其他事故4.60%、泄露中毒3.58%、火灾1.66%.     

2005年9-10月国内安全事故统计分析

统计了2005年9-10月国内发生的各种安全事故573起,包括矿业事故、交通事故、爆炸事故、火灾、毒物泄露和中毒及其他事故.统计表明,在这些事故中,矿业事故最多,占55.32%,平均每天5.2起事故,其次是交通事故(33.86%)、其他事故(4.89%)、爆炸事故(2.62%)、毒物泄露和中毒(1.75%)、火灾(1.57%).573起事故共死亡1 610人,伤1 054人,死亡人数的百分比分别为交通事故47.58%、矿业事故37.33%、其他事故5.84%、爆炸事故4.04%、泄露中毒2.67%、火灾2.55%;受伤人数的百分比分别为交通事故69.92%、其他事故11.86%、矿业事故8.63%、爆炸事故6.74%、泄露中毒1.42%、火灾1.42%.     

基于“2-4”模型的建筑施工高处坠落事故原因分类与统计分析

为了明确建筑施工高处坠落事故的原因分类及各类原因的发生频次概况,采用事故致因“2-4”模型分析了2000—2016年间的56起建筑施工高处坠落事故,并对各类原因进行了分类和统计分析。分析得出安全管理体系缺欠7类共62项,其中,无安全技术交底或技术交底不合格、安全组织机构不合格、无施工组织设计方案或方案不合格出现频次位于前三位;得出安全知识不足62项,安全意识不高58项,较管理者而言,一线操作者的安全知识不足和安全意识不高问题均占多数;得出不安全动作19类共296个,其中,安全培训缺失或不到位和劳动防护用品的缺乏和不正确使用2类不安全动作发生频率较高;得出不安全物态6类共54项,其中出现频率较高的是安全防护栏杆缺失或存在缺陷、脚手架或作业平台搭设不规范、安全网缺失或存在缺陷。     

基于人工影响天气技术的石河子冬季城市空气质量改善试验效果统计分析

采用2019年12月天山北部石河子（目标区）和昌吉（对比区）地区的空气质量指数（AQI）资料,对石河子人工改善空气质量的效果进行了分析,提供了基于人工影响天气技术消减AQI的证据.试验为期31 d,其中在13个试验日中进行了飞机作业.采用区域回归方法,建立两地AQI回归方程,计算目标区在未进行人工作业时的AQI期望值,将其与实测值对比,统计分析作业效果.试验期间,目标区与对比区AQI日变化呈高度的相关性,数据样本相关性经t检验满足要求,经F检验可信程度达到99%,显著性非常高.此外,基于两个随机试验验证统计结果的可靠性.结果表明,在石河子开展人工消雾作业期,AQI指数相较于不进行作业时平均减小52,相对减小28.1%.进一步进行90%置信区间估算结果表明,开展作业后目标区AQI平均值减小了23.71,相对减小15.1%.通过两个蒙特卡洛随机试验表明,人工作业对AQI产生的作用超过了试验期间大部分情况下两地AQI自然变化的区别,因此,统计结果有较高的可信度,在样本数足够时,人工作业的作用可以从复杂的自然变化中体现出来.但是,对于单日内的污染过程,其自然变化十分复杂,人工作业的作用难以进行定量化计算.