2015—2020年湖北省PM2.5和臭氧复合污染特征演变分析

为揭示湖北省PM_2.5和臭氧(O₃)复合污染演变特征,基于湖北省17个地市的空气质量国控点和武汉市大气超级站组分监测数据,全面分析湖北省17个地市2015—2020年PM_2.5和O₃的时空变化特征及相关关系,探讨PM_2.5和O₃协同效应的成因机理. 结果表明:①2015—2020年,湖北省PM_2.5显著改善,平均降幅为4.7 μg/(m3·a),但冬季负荷仍较高,主要集中于中部地区;O₃污染凸显,平均增幅为3.8 μg/(m3·a),污染集中在4—10月的暖季,东部地区最严重,近两年超标天数已与PM_2.5相当. ②湖北省PM_2.5和O₃关联日趋密切,协同效应显著,日评价指标显示夏季二者呈显著正相关(相关系数为0.57),近两年当PM_2.5浓度≤50 μg/m3时,相关系数高达0.63;冬季PM_2.5浓度与O_x(O₃+NO₂)浓度呈正相关,尤其2020年东部城市二者相关性高达0.46,显示大气氧化性对PM_2.5二次污染的重要性. ③以武汉市为例,归纳PM_2.5和O₃复合污染的成因,暖季低PM_2.5背景下,高温、中等湿度和弱风速的气象条件以及VOCs和NO_x等前体物的高浓度排放,使得受VOCs主控的光化学反应加剧,易造成O₃污染,从而加强PM_2.5二次生成;冬季高的大气氧化性,叠加不利气象条件,促进颗粒物的二次生成,导致重污染时PM_2.5组分以硝酸盐等二次无机组分为主. 研究显示,湖北省PM_2.5和O₃协同控制重点为,在保持现有NO_x控制力度基础上强化VOCs控制,遏制暖季和东部区域O₃浓度上升,加强冬季和中部PM_2.5治理.      

基于分步热解技术的沉积岩形态汞同位素分析方法

沉积岩中的汞及其同位素常被用于指示大规模火山活动、海洋氧化还原演变等古环境演化事件,但现有研究主要聚焦总汞含量及相应的总汞同位素组成,缺少形态汞含量及其同位素组成数据,因此无法精准判别古环境中汞的来源、沉积环境和沉积过程。本研究开发了基于热解技术的沉积岩中不同形态汞的分离和同位素分析方法。首先通过沉积岩中典型形态汞（有机质、硫化物和粘土矿物结合态汞）单一标准建立热解温度曲线,然后将上述单一标准物质混合,通过调整升温速率以及形态汞采集的温度范围和时间优化热解分离方法,收集不同温度下析出的气态单质汞进行同位素分析。结果表明,分离的有机质结合态及硫化物结合态汞的δ²⁰²Hg和Δ¹⁹⁹Hg值同参考值的平均差值分别小于0.20‰和0.03‰,因此该分离方法能有效分离上述形态汞并进行汞同位素组成分析。上述方法被进一步应用于分析天然标准物质（黄红壤、水系沉积物、海相沉积岩）的汞形态及其同位素组成,验证了该方法在自然样品中的广泛适用性。     

陕西绥德地区黄土-古土壤序列地球化学特征及其环境指示意义

黄土高原北部的绥德地区处于干旱-半干旱地区,对环境变化的响应十分敏感,通过对黄土-古土壤的研究对比可以探索该区的古环境气候特征、环境变化信息等相关问题.本文对绥德黄土-古土壤进行常量、微量、稀土元素测试分析,并与其他地区黄土的地球化学特征进行了对比.结果 表明:绥德地区黄土-古土壤的主要化学成分以SiO2、Al2O3、...     

荧光法快速测定浮游植物以及应用于梅梁湖预警监测可行性探讨

YSI 6600-V2多功能水质自动监测仪采用荧光原理快速测定水体中浮游植物蓝绿藻的密度,梅梁湖夏季水华高发期时,湖体中的浮游植物几乎全部是蓝绿藻。传统的浮游植物监测前处理方面就需要24~48 h,最终要数天后才有镜检结果,导致浮游植物数据滞后,不能很好的应用到预警监测中。通过比对相关性验证,保证荧光法数据的可信度,提高工作效率,为预警监测提供有力的支持。     

长江上游曲麻莱至玉树段春秋季浮游植物群落结构及多样性评价

于2012年春季（4月）和秋季（10月）对长江上游曲麻莱至玉树段的浮游植物进行初步研究。结果显示：浮游植物共3门62种（属），以硅藻门最多，42种（属），占678%，其次是绿藻门11种（属），占177%，蓝藻门9种（属），占145%。浮游植物优势种为普通等片藻（Diatoma vulgare）、长等片藻（Diatoma elongatum）、尖针杆藻（Synedra acus）、曲壳藻（Achnanthes sp）、舟形藻（Navicula sp）、桥弯藻（Cymbella sp）、脆杆藻（Fragilaria sp）、直链藻（Melosira sp）、异极藻（Gomphonem sp）、菱形藻（Hantzchia sp）、小环藻（Cyclotella sp）、小颤藻（Oscillatoria tenuis）、席藻（Phormidium sp）和小球藻（Chlorella sp）14种，其中硅藻门12种（属），占优势种类的786%。浮游植物种类组成的季节变化不明显，春季（4月）和秋季（10月）均以硅藻为优势种群。浮游植物平均数量3487×104 cells/L，平均生物量0138 8 mg/L，硅藻数量和生物量分别占8786%和9668%,为优势种群。浮游植物现存量表现为春季高于秋季，支流高于干流。Shannon Wiener指数平均值251，Pielou指数平均值070，Marggalef指数平均值089，Shannon Wiener指数、Pielou指数和Marggalef指数是秋季高于春季。结合浮游植物各项评价指标，得出长江上游曲麻莱至玉树段浮游植物群落结构比较稳定，种类分布较为均匀，水体属贫营养型，水域生态环境良好     

Characterizing the Occurrence,Sources, and Variability of Radon in Pacific Northwest Homes

A compilation of data from earlier studies of 172 homes in the Pacific Northwest indicated that approximately 65 percent of the 46 homes tested in the Spokane River Valley/Rathdrum Prairie region of eastern Washington/northern Idaho had heating season indoor radon (²²²Rn) concentrations above the U. S. EPA guideline of 148 Bq m^?3 (4 pCi L^?1). A subset of 35 homes was selected for additional study. The primary source of indoor radon in the Spokane River Valley/Rathdrum Prairie was pressure-driven flow of soil gas containing moderate radon concentrations (geometric mean concentration of 16,000 Bq m^?3) from the highly permeable soils (geometric mean permeability of 5 × 10^?11 m²) surrounding the house substructures. Estimated soil gas entry rates ranged from 0.4 to 39 m³h^?1 and 1 percent to 21 percent of total building air infiltration. Radon from other sources, including domestic water supplies and building materials was negligible. In high radon homes, winter indoor levels averaged 13 times higher than summer concentrations, while in low radon homes winter levels averaged only 2.5 times higher. Short-term variations in indoor radon were observed to be dependent upon indoor-outdoor temperature differences, wind speed, and operation of forced-air furnace fans. Forced-air furnace operation, along with leaky return ducts and plenums, and openings between the substructure and upper floors enhanced mixing of radon-laden substructure air throughout the rest of the building.     

Arizona Hazardous Air Pollutants Monitoring Program

ABSTRACT

In order to evaluate the existing risk to public health in Arizona related to hazardous air pollution, ambient air monitoring for selected hazardous air pollutants (HAPs) was carried out in 1994-1996 in several representative urban and rural areas of Arizona. A wide range of organic HAPs was monitored, requiring a variety of sampling and analysis methods. Stainless steel SUMMA canisters were used for collection of volatile hydrocarbons and halocarbons, which were analyzed by capillary gas chromatography with flame ionization and electron capture detection (GC-FID/ECD). Carbonyl compounds were collected using 2,4-dinitrophenylhydrazine-impregnated cartridges and analyzed by high performance liquid chromatog-raphy with ultraviolet detection. Semi-volatile and non-volatile polycyclic aromatic compounds were collected using a sampling train consisting of a filter followed by a PUF/XAD-4/PUF sandwich cartridge. Following extraction, samples were analyzed by capillary GC with mass spectrometric detection (GC-MS). Database software was developed for data processing and reporting functions. This paper describes the sampling strategy and the sampling and analysis methods employed in the monitoring program and presents a summary of all the results obtained during the duration of the sampling program.