杭州市冬季大气气溶胶PM2.5中二恶英和多氯联苯的污染特征

2014年1月在杭州市选择5个点位采集大气颗粒物PM_2.5样品,采用同位素稀释高分辨气相色谱/高分辨质谱测定PM_2.5中的二恶英（PCDD/Fs）和多氯联苯（PCBs）,对PM_2.5的污染状况以及PM_2.5中PCDD/Fs和PCBs的污染水平及分布特征进行了研究。PM_2.5的质量浓度范围为85~168 μg/m³,PM_2.5污染较重,但与2004年同期相比明显降低。PM_2.5中PCDD/Fs的毒性当量（TEQ）为0.277~0.488 pg I-TEQ/m³,明显高于2004年同期采集样品。颗粒物中PCDD/Fs以八氯代二苯并-对-二恶英（OCDD）为主,毒性当量主要贡献者为2,3,4,7,8-五氯代二苯并呋喃（2,3,4,7,8-PeCDF）。PM_2.5中PCBs的质量浓度范围为2.9~8.1 pg/m³,二恶英类多氯联苯（DL-PCBs）的毒性当量范围为2.6~6.1 fg WHO-TEQ/m³,污染较低。PCBs在颗粒物中分布以PCB-28为主,但对毒性当量贡献最大的为PCB-126。PCDD/Fs和PCBs的气-固分配特征表现为PCDD/Fs主要分布于颗粒物中,而PCBs主要分布于气相中。     

秸秆燃烧排放PM2.5特征及影响因素研究

生物质燃烧向大气中排放大量颗粒污染物, 在中国, 收获季节大量秸秆被直接露天燃烧处理, 对区域环境质量和人体健康造成严重影响. 对我国最主要的两种粮食作物玉米和小麦秸秆的露天燃烧进行模拟, 分析颗粒物排放水平, 特征及影响因素. 玉米和小麦秸秆燃烧PM_2.5排放因子分别为1082.8和835.7~897.3 mg/kg. 有机物是颗粒物最主要组分, 总量占PM_2.5质量的42%~66%. Cl^-和K⁺分别占PM_2.5总质量的4%~15%和2%~14%, K⁺/EC值为0.5~3.8. 各物种在颗粒物中所占比例与之前研究结果一致. 秸秆含水量和燃烧温度影响PM_2.5排放水平和组成特征. 随秸秆含水量增加, PM_2.5和OC的排放因子增加; 秸秆含水量增加, 燃烧温度逐渐降低, 由生物质燃料释放进入烟气中的K⁺和Cl^-比例逐渐减小导致二者在颗粒物中的比例降低. 我国每年由玉米和小麦秸秆露天燃烧排放的PM_2.5和OC分别为92.7 Gg和47.5 Gg, 在总量中占重要比例.     

微波灰化-液相色谱-电感耦合等离子体质谱联用测定干食用菌中的三价铬和六价铬

建立了干食用菌中三价铬(Cr(Ⅲ))和六价铬(Cr(Ⅵ))的液相色谱-电感耦合等离子体质谱(LC-ICP-MS)检测方法。采用微波灰化技术对食用菌样品进行灰化处理,灰化样品用乙二胺四乙酸(EDTA)二钠盐稳定其中的Cr(Ⅲ),并使其保留在阴离子交换柱(250 mm×4.6 mm,10 μm)上;用含有60 mmol/L硝酸(pH 9.3)的流动相分离其中的Cr(Ⅲ)和Cr(Ⅵ),电感耦合等离子体质谱仪测定。标准溶液中Cr(Ⅲ)和Cr(Ⅵ)的质量浓度在0.5~50 μg/L范围内呈良好的线性关系,线性回归系数均达到0.9999。食用菌样品中Cr(Ⅲ)和Cr(Ⅵ)不同加入量的平均回收率为78.0%~90.7%,相对标准偏差小于4%(n=6);定量限均为0.5 μg/L。该方法稳定、可靠、灵敏,可满足干食用菌中Cr(Ⅲ)和Cr(Ⅵ)的测定。     

电感耦合等离子体质谱法测定PM2.5中的重金属元素

采集环境空气细颗粒物(PM2.5)样品,建立了电感耦合等离子体质谱法(ICP-MS)同时测定PM2.5中10种重金属元素的方法。样品经5%HNO_3超声浸提,过滤后,用ICP-MS测定。结果表明:10种重金属元素的检出限在0.030μg/L~0.13μg/L之间;线性关系良好,精密度为0.82%~4.3%,回收率为80.1%~113.0%。该方法快速、准确,可用于PM2.5中重金属元素的测定。     

智能石墨消解–ICP–MS法测定空气PM2.5中的Pb和Cd

建立电感耦合等离子体质谱(ICP–MS)测定空气PM2.5中的Pb和Cd元素的分析方法。采用连续β射线–DHS PM2.5大气颗粒物浓度监测仪采集空气中的PM2.5,以智能石墨消解PM2.5滤膜样品,ICP–MS测定其中的Pb和Cd元素含量。在优化的仪器条件下,元素Pb和Cd标准曲线的线性相关系数均为0.999 9,检出限分别为0.018,0.52ng/m3,满足HJ 657–2013的要求。Pb和Cd的加标回收率分别为95.8%~101.4%,99.3%~104.9%,测定结果的相对标准偏差分别为4.20%和2.38%(n=6)。对滤膜标准样品进行了测定,测定结果与标准值一致。该方法测定结果准确、可靠,可用于测定空气PM2.5中的Pb和Cd。     

共沉淀法辅助分离-离子色谱与电感耦合等离子体质谱联用测定玩具材料中三价铬及超痕量六价铬

采用0.07 mol/L盐酸萃取样品,取一部分萃取液用电感耦合等离子体质谱法(ICP-MS)测定可迁移总铬含量,另一部分萃取液通过Al(NO3)3共沉淀法去除高含量干扰阳离子后用离子色谱-电感耦合等离子体质谱联用法(IC-ICP-MS)测定六价铬(Cr(Ⅵ))含量,用可迁移总铬量减去Cr(Ⅵ)含量求得Cr(Ⅲ)含量,可迁移总铭及Cr(Ⅵ)的方法定量下限分别达0.01 mg/kg和0.003 mg/kg。选取2009/48/EC玩具新指令涉及的玩具材料进行加标及阳性样品验证,可迁移总铭及Cr(Ⅵ)的加标回收率分别为90.2%~101.5%和96.7%~106.7%,实验室间相对标准偏差分别不高于7.4%和7.9%。方法准确可靠,可实现玩具新指令所涉及的3类玩具材料中Cr(Ⅲ)及Cr(Ⅵ)的检测。     

微波消解–原子荧光法同时测定PM2.5中砷、汞含量

采用微波消解–原子荧光法测定PM2.5中砷、汞含量。实验结果表明,当还原剂硼氢化钾的质量分数为2%、溶液介质酸度为4%(体积分数)盐酸时,同时测定砷、汞可获得最佳的荧光值。砷、汞测定的检出限分别为0.027,0.006μg/L,空白滤膜的加标回收率分别为95.3%~101.7%,96.0%~106.0%,样品的加标回收率分别为95.0%~103.5%,93.3%~110.0%。该法检出限低,准确度高,适用于环境空气PM2.5中砷、汞含量的测定。     

碱消解–石墨炉原子吸收光谱法测定PM10中的六价铬

在碱性介质中,加入氯化镁和磷酸氢二钾–磷酸二氢钾缓冲溶液,95℃水浴消解溶出样品中的Cr(Ⅵ),采用石墨炉原子吸收光谱法测定TEOM膜中PM10的Cr(Ⅵ)含量。Cr(Ⅵ)质量浓度在0.0~2.0μg/L范围内与吸光度线性良好,相关系数为0.999 7。当采集1 000 m3环境空气时,方法检出限为2.10×10–6μg/m3。实际样品加标回收率为89.0%~94.3%,测定结果的相对标准偏差为2.2%(n=7)。该法满足环境空气质量标准中规定的Cr(Ⅵ)年平均浓度2.5×10–5μg/m3限值的要求。     

435 m2烧结机机头化学团聚强化细颗粒物及重金属脱除试验研究

针对某435 m²烧结机机头,在静电除尘器前安装化学团聚强化除尘系统,研究化学团聚强化细颗粒物及重金属（As、Cr、Cd、Ni、Cu、Pb、Zn七种）脱除特性。实验结果表明,化学团聚后,细颗粒团聚成较大颗粒,静电除尘器后烟气中PM₁₀、PM_2.5、PM₁颗粒质量浓度均降低49%以上,静电除尘器飞灰平均粒度增长46%以上,细颗粒物团聚效果显著,提升了静电除尘器脱除细颗粒物效率;静电除尘器飞灰及细颗粒物中重金属质量浓度上升,静电除尘器后烟气中重金属质量浓度均下降,表明化学团聚作用促使气态重金属向颗粒态重金属及飞灰中迁移,细颗粒重金属团聚长大。化学团聚不仅可以强化细颗粒物的脱除,同时有效提升了重金属的脱除效率。     

碱熔-电感耦合等离子体发射光谱法测定大气颗粒物中的硅

建立了NaOH碱熔-电感耦合等离子体发射光谱法测定大气颗粒物中硅含量的方法。采用聚丙烯膜采集大气颗粒物,以NaOH为熔融剂,用HCl溶液进行酸化,并用电感耦合等离子体发射光谱在最佳波长251.611 nm下测定硅含量。结果表明,当采样体积为150 m~3(标准状态)时,大气颗粒物中硅元素的检出限为33 ng/m~3,相对标准偏差小于2%,加标回收率在89.7%～103.3%之间。土壤标样与特氟龙膜、聚丙烯膜模拟实际样品对比检测结果显示,特氟龙滤膜灰化造成硅损失,聚丙烯膜更适用于碱融法消解大气颗粒物样品时硅的测定。该方法适用于大批量大气颗粒物中硅的准确测定。     

液相色谱-质谱法对饮用水中六价铬的测定

建立了液相色谱分离、电喷雾质谱测定饮用水中六价铬的方法.水样经微孔滤膜过滤后直接进样,以乙腈-1.5 mmol/L四丁基氢氧化铵水溶液为流动相,Xterra~(TM) MS C_(18)色谱柱分离六价铬,使用单四极杆质谱,选择离子模式检测,监测离子为m/z 118、117、101、85,其中117为定量离子.Cr(Ⅵ)的线性范围为1.0 ～100.0 μg/L,方法定量下限为1 μg/L.在空白水样中分别添加1.0、2.0、10.0 μg/L的六价铬,测得平均回收率(n=5)依次为91%、94%、97%,相对标准偏差分别为12.2%、7.4%、3.5%.测定了42个饮用水样品,其中17批检出六价铬,检出量为1.2 ～15.4 μg/L.     

Pollution characteristics of atmospheric fine particles and their secondary components in the atmosphere of Shenzhen in summer and in winter

Two field measurements for atmospheric fine particles were conducted in Baoan district of Shenzhen during the summer and winter in 2004. Totally 30 sets of 24 h samples were collected, and then the mass concentrations and chemical compositions were determined. The seasonal varia- tions and secondary pollution characteristics of fine particles during the sampling periods were dis-cussed with meteorological factors. The results show that seasonal variations of atmospheric particles are significant in Shenzhen. The average mass concentrations of PM2.5 and PM10 in summer were 35 μg·m-3 and 57 μg·m-3, respectively, and those in winter were 99 μg·m-3 and 135 μg·m-3, respec-tively. The concentrations of both PM2.5 and PM10 in winter increased 184% and 137%, respectively, compared to those in summer. PM2.5 accounted for 61% and 75% of PM10 in summer and in winter, respectively, indicating severe fine particle pollution in Shenzhen. During the summer and winter sampling periods, the mean OC/EC ratios were 3.4 and 1.6, respectively. The estimated secondary organic carbon (SOC) averagely accounted for 56% and 6% of the total OC in summer and in winter, respectively, which implies a major contribution of SOC to OC in summer. During the continuous high temperature period in summer, both the concentrations and fractions of secondary aerosol compo-nents in PM2.5 were highly elevated, suggesting severe secondary pollution again. The prevailing wind was from South China Sea in summer, and the air quality was good. The prevailing wind in winter was from Mainland China to the north, and the polluted air mass led to poor air quality.     

Determination of hexavalent chromium in traditional Chinese medicines by high‐performance liquid chromatography with inductively coupled plasma mass spectrometry

An analytical method that combined high‐performance liquid chromatography with inductively coupled plasma mass spectrometry has been developed for the determination of hexavalent chromium in traditional Chinese medicines. Hexavalent chromium was extracted using the alkaline solution. The parameters such as the concentration of alkaline and the extraction temperature have been optimized to minimize the interconversion between trivalent chromium and hexavalent chromium. The extracted hexavalent chromium was separated on a weak anion exchange column in isocratic mode, followed by inductively coupled plasma mass spectrometry determination. To obtain a better chromatographic resolution and sensitivity, 75 mM NH₄NO₃ at pH 7 was selected as the mobile phase. The linearity of the proposed method was investigated in the range of 0.2–5.0 μg L^?1 (r² = 0.9999) for hexavalent chromium. The limits of detection and quantitation are 0.1 and 0.3 μg L^?1, respectively. The developed method was successfully applied to the determination of hexavalent chromium in Chloriti lapis and Lumbricus with satisfactory recoveries of 95.8–112.8%.     

超痕量六价铬分析仪检测制革场地中六价铬

为解决制革等污染场地中Cr(III)-有机络合物会干扰六价铬测定的问题,通过优化仪器色谱条件、在现有行标基础上改进前处理方式,使用超痕量六价铬分析仪检测六价铬,并通过在土壤中投加低、中、高浓度的三价铬、六价铬以及Cr(III)-有机络合物考察三价铬、色度和Cr(III)-有机络合物对六价铬测定的影响。结果表明仪器的最佳色谱条件为：流动相浓度为0.1 mol/L、流动相pH为9、浓硫酸用量为5 mL、流动相流速为1.2 mL/min,衍生试剂流速为0.7 mL/min。样品预处理方式由抽滤提取改进为离心提取,上机前样品pH无需调节,可提高检测效率;该方法与现行行标相比操作简便、耗时短且不受三价铬、样品色度及Cr(III)-有机络合物的干扰。方法精密度和正确度均显著提高,相对标准偏差为1.7%~5.2%,回收率均在94.6%~103%之间。通过与液相色谱-电感耦合等离子体质谱仪对实际样品测定结果的统计学检验发现,结果无显著性差异。该方法适用于制革、电镀等富含Cr(III)-有机络合物场地中六价铬的测定。     

Cr(III)/Cr(VI) speciation in aerosol particles by extractive separation and thermal ionization isotope dilution mass spectrometry

 An isotope dilution mass spectrometric (IDMS) method, using the formation of positive thermal ions, was developed for Cr(III) and Cr(VI) speciation in aerosol particles. Cr(III) and Cr(VI) spike species, enriched in ⁵³Cr, were applied for the isotope dilution step. After leaching of filter collected aerosol samples by an alkaline solution at pH 13, species separation was carried out by extraction with a liquid anion exchanger in methyl isobutyl ketone. Cr(VI) in the organic phase was re-extracted into an ammoniacal solution and chromium was then isolated from both fractions of species by electrodeposition. Detection limits of 30 pg/m³ for Cr(III) and of 8 pg/m³ for Cr(VI) were achieved in atmospheric aerosols for volumes of air samples of about 120 m³. These low detection limits allowed the determination of chromium species in continental aerosol particles in dependence on different seasons. The Cr(III) /Cr(VI) ratio was always found to be about 0.3 whereas dust from soil erosion, which is probably the primary source of chromium in the atmosphere, showed higher ratios. This indicates that chromium is oxidized in the atmosphere. The accuracy of the method was demonstrated in two interlaboratory comparisons of Cr(VI) determinations in welding dust samples. The IDMS method also contributed to the certification of a corresponding standard reference material organized by the Standard Reference Bureau of the European Union. Chromium speciation, including the determination of elemental chromium Cr(0), was carried out in aerosols of different welding processes for stainless steel. These analyses showed distinct differences in the distribution of chromium species in the welding process and can be used as an exact calibration method for routine methods in this important field of monitoring corresponding working places. Received: 19 August 1996/Revised: 24 September 1996/Accepted: 28 September 1996     

嵌段分子筛聚合材料P123-SH萃取分离-石墨炉原子吸收光谱法分析痕量铬的形态

研究了嵌段分子筛聚合材料P123-SH萃取分离-石墨炉原子吸收光谱法对尿中痕量铬的形态分析方法,探讨了嵌段分子筛聚合材料P123-SH吸附铬的原理和最佳条件。在pH 7.0、常温下,Cr3+和Cr(Ⅵ)被很好的分离,且Cr3+可被该材料定量吸附,其吸附容量为6.15 mg/g。吸附的Cr3+可用2 mol/L的HCl洗脱,用石墨炉原子吸收法测定洗脱下来的Cr3+,往溶液中加入0.1%抗坏血酸将Cr(Ⅵ)还原为Cr3+测总铬,Cr(Ⅵ)含量为总铬减去Cr3+,方法测定Cr3+的检出限为0.011μg/L(3σ,n=11),线性范围为0.1～10μg/L,加标回收率在94%～106%之间,对0.50μg/L的Cr3+溶液平行测定7次,RSD为3.6%。方法可应用于生物样品和环境样品中痕量铬的形态分析。     

Utilization of Cr(VI) solutions with steel shavings

New single-stage method was developed for chemical utilization of wastewater containing 0.25 to 400 g L^–1 of chromium in terms of chromium anhydride with the us of sulfuric acid and steel cuttings. The method makes it possible to convert hexavalent chromium into easily used ferrochromium precipitates. It was found that there occur periodic synchronous concentration fluctuations of Cr(VI) and Cr(III) up to, respectively, 400 g L^–1 and 150 mg L^–1 in the course of reduction of hexavalent chromium with the use of steel cuttings in sulfuric acid solutions.     

微乳相萃取分离富集-原子吸收光谱法分析铬形态

建立了一种微乳相萃取分离-石英双缝管原子捕集火焰原子吸收光谱法(STAT-FAAS)分析环境水样中铬形态的新方法。该方法中,Cr(Ⅲ)与8-羟基喹啉反应形成的疏水性配合物,经萃取进入微乳相,Cr(Ⅵ)留在水溶液中,从而实现Cr(Ⅲ)与Cr(Ⅵ)的相互分离。Cr(Ⅵ)含量的测定通过过氧化氢溶液将Cr(Ⅵ)还原为Cr(Ⅲ),按同样方法分析。实验对微乳相萃取的主要影响因素进行了优化。结果表明,经优化后实验条件为:平衡温度80℃,平衡时间10min,溶液酸度pH=9.0,NH3-NH4Cl缓冲溶液用量2.0mL,8-HQ用量0.05mmol;TritonX-100微乳液组成:m(TritonX-100):m(正戊醇):m(正己烷):m(水)=3.0:15:1.5:4.0。在此条件下,萃取的富集倍数达到25倍(50mL起初样品溶液/2mL最终测定液),线性范围为2.5～500μg/L,检出限为0.62μg/L,相对标准偏差(RSD)为3.8%(n=10,c=10μg/L)。本方法已成功地应用于电镀废水中铬形态分析。     

流动注射分光光度法快速测定水样中的铬

建立了用流动注射分光光度法快速检测水样中铬含量的方法.测定耗时140 s,测定频率25样/h.本法利用Cr(Ⅵ)和二苯碳酰二肼显色反应,Cr(Ⅵ)标准溶液的质量浓度在0.05～0.8 mm/L之间与吸光度呈线性.该法的检出限是4.0 μg/L,低于国家对Ⅰ类水的相关标准.应用此法分别测定了北京城区一些地表水中铬的含量,加标回收率在90.1%～113%之间.