共查询到19条相似文献,搜索用时 78 毫秒
1.
2014年3月13日至4月20日在福建三明市利用PM_(2.5)中流量采样器采集大气中PM_(2.5)膜样品,测定了PM_(2.5)的质量浓度,并用热/光碳分析仪和离子色谱分析了其组分变化特征.结果表明,三明市观测期间PM_(2.5)的平均质量浓度为73.61±0.73μg/m~3,有机碳(OC)和元素碳(EC)的平均质量浓度分别为7.26±1.00和5.63±0.27μg/m~3,水溶性离子中SO_4~(2-)、NH_4~+、NO_3~-和Na~+的质量浓度分别为18.08±12.19、4.18±3.56、2.77±1.16和2.73±0.23μg/m~3,总和占总水溶性离子的87.76%.结合后向轨迹分析了福建三明市的污染物来源特征.该地区OC/EC的平均比值小于2,SOC(二次有机碳)生成量很少,主要以一次有机污染物为主,OC、EC与K~+的相关性分析表明OC、EC与K~+的来源相近,可以判断OC、EC绝大部分来源是生物质燃烧产生的污染物.在水溶性离子分析中,观测期间NO_3~-/SO_4~(2-)为0.159±0.02,表明三明市主要以固定源为主,机动车辆等移动源贡献较少. 相似文献
2.
《长春理工大学学报(自然科学版)》2020,(3)
为了了解气溶胶含水量主要影响因子,于2015年秋季在珠三角典型城市广州同步在线观测了PM_(2.5)及其中主要化学成分的质量浓度、干湿散射系数和气象因子,在此基础上利用Mie模型和ISORROPIA模型分别估算了气溶胶含水量(LWC_(neph))和无机盐含水量(LWC_(ISO)),分析了LWC_(neph)和LWC_(ISO)的主要影响因子。结果显示,秋季观测期间PM_(2.5)浓度均值47μg·m~(-3),OM(organic matter)、EC、NH_4NO_3和(NH_4)_2SO_4浓度均值分别为13.0、3.4、5.2和14.4μg·m~(-3),上述4类化学物种占PM_(2.5)浓度76%。LWC_(neph)和LWC_(ISO)之间存在较好的线性关系(R~2=0.81),斜率为1.03。相对湿度和无机盐(NH_4NO_3和(NH_4)_2SO_4)对LWC_(neph)和LWC_(ISO)起着主导性作用。相同湿度条件下,NH_4NO_3相对含量的变化对LWCISO浓度的影响明显大于(NH_4)_2SO_4。低相对湿度条件下,OM对LWC_(neph)的影响大于无机盐。 相似文献
3.
邯郸市大气污染特征及变化趋势研究 总被引:1,自引:1,他引:1
利用邯郸市四个空气质量监测站点,2013~2014连续两年的颗粒物及气态污染物在线观测数据和气象数据对该市大气污染状况进行分析,结果表明:邯郸市大气污染以细颗粒物为主,2013、2014年邯郸市PM2.5年均浓度分别为139μg/m3和116μg/m3,为国家二级标准(35μg/m3)的近4倍和近3倍,2014年较2013年有所缓解,浓度下降比例为16.5%,超标率由2013年的74.4%降低到2014年的66.6%;邯郸市PM2.5浓度的空间分布并无明显差异;PM2.5季节变化规律为冬季秋季春季夏季,PM10季节变化规律为冬季春季秋季夏季;邯郸市PM2.5和PM10在一周内的浓度差异均较小,说明邯郸市污染物排放的周变化不明显,工业等排放较为稳定的行业占其排放的主导地位;与气象条件的相关性分析表明,邯郸市四季中静风频率最高,邯郸市的风向主要集中在从东到南到西这一方向带上,河南、山东、山西三省对于邯郸市颗粒物的贡献较大。 相似文献
4.
《西安建筑科技大学学报(自然科学版)》2014,(6)
为了探讨西安市PM2.5和碳气溶胶质量浓度变化特征,从2012年3月~2013年2月对西安市大气PM2.5进行了为期一年的观测,并分析了有机碳(OC)和元素碳(EC)的质量浓度变化特征.结果显示,西安市2012年3月~2013年2月日均PM2.5质量浓度变化幅度为26.9~505.1μg/m3,PM2.5年平均质量浓度为114.0±86.6μg/m3,是中国PM2.5空气质量标准(GB3095-2012)年平均二级标准值(35μg/m3)的3.3倍.PM2.5季节变化特征为冬季秋季春季夏季.OC和EC年平均浓度值为21.44±15.76μg/m3和6.16±3.38μg/m3,OC/EC年平均值为3.37±0.95,变化范围为1.80~5.84,表明有二次有机碳气溶胶的存在.主成分分析法表明,西安市大气中的碳气溶胶主要来自汽油车和柴油车尾气、二次碳气溶胶以及生物质燃烧. 相似文献
5.
为了探究太行山东麓煤矿区气溶胶中重金属元素的污染特征及来源,于2017年春、夏、秋、冬四季分别在峰峰矿区采集PM_(2.5)和PM_(10)样品,使用电感耦合等离子体质谱(ICP-MS)测试样品中的重金属元素,分析讨论PM_(2.5)和PM_(10)中重金属元素的污染特征。结果表明,峰峰矿区春、夏、秋、冬四个季节PM_(2.5)的平均质量浓度分别为84、108、107和174μg/m~3,春、夏、秋季PM_(10)质量浓度分别为204、177和179μg/m~3,均超过我国环境质量二级标准,表明矿区大气污染较为严重;PM_(2.5)/PM_(10)的比值夏秋季明显高于春季,这可能与夏秋季强烈的光化学反应生成大量二次粒子有关;峰峰矿区PM_(2.5)中Zn元素含量最高,Pb次之,其他元素含量由高到低依次为Mn、Cr、Cu、As、Mo、V、Sn、Ni、Cd、Co。PM_(10)中Zn元素含量最高,Mn次之,其他元素含量由高到低依次为Pb、Cr、Cu、V、As、Mo、Ni、Sn、Cd、Co。峰峰矿区PM_(2.5)和PM_(10)中Cd元素的富集系数超过100,严重富集,明显受到人为活动影响;Mo、Pb、Sn、Zn元素富集系数均超过了10,表明Mo、Pb、Sn、Zn等四种元素在峰峰矿区轻微富集,受到人为活动影响;Cu、As、Cr、Ni、V、Mn、Co元素的富集系数小于10,表明Cu、As、Cr、Ni、V、Mn、Co这七种元素主要来自于地壳。 相似文献
6.
为研究唐山PM_(2.5)污染特征及区域传输贡献,对唐山冬夏2季PM_(2.5)环境样品进行测试分析,并采用WRFCAMx对京津冀地区PM_(2.5)及二次离子进行定量模拟,获取了PM_(2.5)成分谱数据,估算了PM_(2.5)和二次离子的区域传输贡献.唐山冬夏2季PM_(2.5)平均质量浓度分别为(117.9±56.6)、(77.3±29.8)μg/m3,超标率分别为65.0%和41.7%;水溶性离子的平均质量浓度分别为(58.4±17.9)和(42.6±23.6)μg/m~3,分别占PM_(2.5)的49.4%和55.0%,是PM_(2.5)的主要成分.Cu、Zn、As、Sr、Cd、Sb、Pb主要来自人为源,Na、Mg等其余元素主要来自地壳源.冬夏2季PM_(2.5)受外来源贡献分别为26.9%和31.1%,二次无机气溶胶(secondary inorganic aerosol,SIA)传输作用较PM_(2.5)更为显著,夏季PM_(2.5)和SIA外来源贡献高于冬季,高质量浓度时段外来源贡献会有一定幅度的上升.稳定的大气环流背景场、低风速等气象条件和燃煤排放源的增加是造成冬季重污染发生的重要原因. 相似文献
7.
利用银川市大气颗粒物组分监测网在线观测数据,分析了2018年7月沙尘天气下不同粗细颗粒物(TSP,PM_(10),PM_(2.5),PM_1)的质量浓度变化趋势,PM_(2.5)中的水溶性离子、金属元素、有机碳(OC)和元素碳(EC)的质量浓度变化趋势和污染来源,及本次沙尘过程区域污染传输情况。结果表明,7月14—18日受沙尘天气过境影响,TSP,PM_(10)的小时质量浓度均在15日10:00达到了峰值,分别为2 692,2 173μg/m~3,PM_(2.5)的小时质量浓度在15日9:00达到了峰值,为608μg/m~3,PM_1的小时质量浓度峰值出现在7月16日15:00,为54.2μg/m~3;7月沙尘期PM_(2.5)中水溶性离子日均质量浓度由大到小排序为Ca~(2+)SO_4~(2-)NH_4~+Mg~(2+)Na~+K~+NO_3~-,Ca~(2+)日均质量浓度增幅最大,升高16.2倍,PM_(2.5)中金属元素日均质量浓度由大到小排序为CaFeKMnPbCrZnVTiCuNiAs,Ca日均质量浓度为31 945.6 ng/m~3,PM_(2.5)中有机碳和元素碳的日均质量浓度分别为7.22,1.09μg/m~3,比值为6.6。后向轨迹图和气溶胶激光雷达消光图显示,本次沙尘污染是由外来源输入的颗粒物沉降和本地地面扬尘叠加共同造成。 相似文献
8.
校园建筑室内通风不良可造成室内空气品质下降,进而影响室内人员的学习效率和健康.研究选取北京某大学26间公寓测试44次、8间办公室测试14次和26间教室测试43次,在冬夏两季对室内新风量进行测试分析.研究结果表明,冬季大学生公寓、办公室和教室新风量达标率(0~20%)远低于夏季达标率(22.2%~81.8%).冬、夏季公寓新风量为1.75~54.41 m~3/(人·h)(0.13~3.82 h~(-1))和2.8~134.43 m~3/(人·h)(0.2~9.62 h~(-1)),教室新风量为0.39~15.24 m~3/(人·h)(0.02~2.36 h~(-1))和1.51~158.45 m~3/(人·h)(0.11~8.19 h~(-1)),办公室新风量为1.14~44.6 m~3/(人·h)(0.07~2.89 h~(-1))和17.9~74.0 m~3/(人·h)(1.16~4.81 h~(-1)).公寓和教室新风量季节性差异的显著性与否与窗户开/关有关,而办公室新风量季节性差异不显著,而朝向和楼层对公寓新风量的影响不明显.大学生公寓、办公室和教室新风不足,应采取措施加强通风. 相似文献
9.
《淮海工学院学报》2018,(4)
为研究江苏海涂海域浮游动物群落结构及季节变化,分别于2012年10月(秋季)、2013年5月(春季)和2014年8月(夏季)对江苏海涂海域进行了3个不同季节的浮游动物调查.调查结果显示,江苏海涂海域共鉴定到浮游动物68种,种类数为夏季(51种)春季(33种)秋季(17种);3个季节的生物量为春季(180.17mg/m~3)夏季(157.98mg/m~3)秋季(35.98mg/m~3),丰度为春季(116.13ind/m~3)夏季(43.35ind/m~3)秋季(26.31ind/m~3),3个季节生物量和丰度的峰值均出现在东台及以南海域;真刺唇角水蚤(Labidocera euchaeta)和长额刺糠虾(Acanthomysis longirostris)为研究海域3个季节共同的优势种,优势度最高的为中华哲水蚤(Calanus sinicus);3个季节的浮游动物多样性指数平均值为1.99,夏季(2.37)春季(1.81)秋季(1.79),江苏海涂海域整体群落结构相对较为简单. 相似文献
10.
PM2.5属于大气细颗粒物,能够长时间悬浮于空气中且易被人体吸入,影响人类的身体健康。以河南省18个观测站逐小时PM2.5浓度数据为研究对象,采用数理统计、反距离权重和地理探测器等方法,探讨河南省PM2.5浓度的时间和空间变化特征及其影响因素。研究表明:(1)年际尺度上,2017—2022年河南省年均PM2.5浓度呈下降趋势。(2)季节尺度上,四季PM2.5平均浓度由高到低依次为:冬季(89.5±16.2μg/m3)、秋季(48.5±5.5μg/m3)、春季(41.4±6.1μg/m3)、夏季(28.8±7.3μg/m3),冬季平均浓度远高于其他三季。(3)月份尺度上,PM2.5浓度呈“U”型变化特征,1~7月呈降低趋势,8~12月呈增加趋势,其中1月浓度最高(107.9±12.2μg/m3),7月浓度最低(27.0±10.6μg/m3<... 相似文献
11.
Guo Hua-jun Li Xin-hai Zhang Xin-ming Zeng Su-ming Wang Zhi-xing Peng Wen-jie 《中南工业大学学报(英文版)》2005,12(1):44-49
LiNi0.45Co0.10Mn0.45O2 was synthesized from Li2CO3 and a triple oxide of nickel, cobalt and manganese at 950 °C in air. The structures and characteristics of LiNi0.45Co0.10Mn0.45O2, LiCoO2 and LiMn2O4 were investigated by XRD, SEM and electrochemical measurements. The results show that LiNi0.45Co0.10Mn0.45O2 has a layered structure with hexagonal lattice. The commercial LiCoO2 has sphere-like appearance and smooth surfaces, while the LiMn2O4 and LiNi0.45Co0.10Mn0.45O2 consist of cornered and uneven particles. LiNi0.45Co0.10Mn0.45O2 has a large discharge capacity of 140.9 mA · h/g in practical lithium ion battery, which is 33.4% and 2.8% above that of
LiMn2O4 and LiCoO2, respectively. LiCoO2 and LiMn2O4 have higher discharge voltage and better rate-capability than LiNi0.45Co0.10Mn0.45O2. All the three cathodes have excellent cycling performance with capacity retention of above 89.3% at the 250th cycle. Batteries
with LiMn2O4 or LiNi0.45Co0.10Mn0.45O2 cathodes show better safety performance under abusive conditions than those with LiCoO2 cathodes.
Foundation item: Project(50302016) supported by the National Natural Science Foundation of China; Project(2005037698) supported by the Postdoctoral
Science Foundation of China 相似文献
12.
为研究不同污泥龄(SRT)条件下厌氧氨氧化菌的脱氮效能和动力学特性,采用一组SBR反应器研究梯度降低污泥龄过程中系统的NO2--N去除负荷(Nr)和NO2--N污泥负荷(Ns),并对各阶段厌氧氨氧化过程动力学特性进行分析.结果表明,污泥龄由21 d梯度降低到12 d,Nr由0.590 kg/(m3·d)降低到0.493 kg/(m3·d),单位MLVSS Ns由0.178 kg/(kg·d)提升到0.297 kg/(kg·d),系统整体的脱氮性能有所下降,但单位质量的厌氧氨氧化菌脱氮效率显著提升;采用莫诺(Monod)模型可以较好地模拟不同污泥龄运行阶段厌氧氨氧化菌的动力学行为,动力学分析表明,随着污泥龄的降低,NO2--N的最大比降解速率vmax由0.406 d-1提高到0.826 d-1,半饱和常数Ks由23.3 mg/L增加到95.3 mg/L,梯度降低污泥龄能够筛选纯化生长速率较快的厌氧氨氧化菌菌种,提升NO2--N的最大比降解速率,但厌氧氨氧化菌对底物的亲和性会逐渐变差,稳定性降低. 相似文献
13.
付承菊 《武汉理工大学学报(材料科学英文版)》2008,23(5):622-624
The Bi4Ti3Oi2 and Bi3.25La0.75Ti3O12 thin films were prepared on the Pt/Ti/SiO2/Si substrate using the sol-gel method. The effect of La doping on the microstructure and ferroelectric properties of Bi4Ti3O12 films were investigated. Both the Bi4Ti3O12 and Bi3.25La0.75Ti3O12 thin films exhibited typical bismuth layered perovskite structure. The 2Pr (remanent polarization) value of Bi3.25La0.75Ti3O12 thin films is 18.6 μC/cm^2, which is much larger than that of Bi4Ti3O12 thin films. And the Bi3.2eLa0.75Ti3O12 films show fatigue-free behavior, while the Bi4Ti3O12 thin films exhibit the fatigue problem. The mechanism of improvement of La doping was discussed. 相似文献
14.
隋万美 《武汉理工大学学报(材料科学英文版)》2009,24(2):241-244
Bismuth titanate (Bi4Ti3O12) platelets were prepared by molten salt method in a new salt system of CaCl2-NaCl at 650–750 °C, using bismuth nitrate pentahydrate (Bi(NO3)3―H2O) and titanium butoxide (Ti (OC4H9)4) as raw materials. The synthesis temperature of Bi4Ti3O12 platelets was decreased to 650 °C from 900–1100 °C. The phase compositions and crystalline morphology of Bi4Ti3O12 platelets were investigated by XRD and SEM. The experimental results indicate that Bi4Ti3O12 platelets containing tetragonal and orthorhombic phase with the size of 1–3 μm can be synthesized at 650 °C for 2 h, and
the orthorhombic phase becomes the dominant phase at 750 °C for 5 h. The size and proportion of Bi4Ti3O12 platelets increase with the increment of the calcining temperature and holding time. The proportion of platelets increases
to about ninety percent, and the platelets grow up to about 3–10 μm at 750 °C for 5 h from 1–2 μm at 650 °C for 2 h. This
technical route provides a new low-temperature molten salt system for preparing platelets by molten salt methods. 相似文献
15.
何峰 《武汉理工大学学报(材料科学英文版)》2008,23(4):562-565
The technology and microstructure of glass-ceramics and ceramic composite materials were studied. A suitable ceramic body was chosen on the basis of the sintering temperature of CaO-Al2O3-SiO2 system glass-ceramics. According to the expansion coefficient of the ceramic body, that of CaO-Al2O3-SiO2 system glass-ceramics was adjusted, fl-wollastonite was found present as the major crystalline phase in glass- ceramic. The CaO-Al2O3-SiO2 system glass-ceramic layer and ceramic body could be sintered together by adjusting the sintering period. The compositions of glass-ceramic layer and ceramic body diffuse mutually at 1 100 ℃, resulting in an interface between them. To achieve good sintered properties of glass-ceramics and the chosen ceramic body, at least a four-hour sintering time is used. 相似文献
16.
于志强 《武汉理工大学学报(材料科学英文版)》2007,22(1):48-51
TiB2-Al2O3 composite powders were produced by self-propagating high-temperature synthesis(SHS) method with reductive process from B2O3-TiO2-AI system. X-ray diffraction(XRD) and scanning electron microscopy(SEM) analyses show the presence of TiB2 and Al2O3 only in the composite powders produced by SHS. The powders are uniform and free-agglomerate. Transmission electron microscopy (TEM) and high resolution electron microscopy (HREM) observation of microstructure of the composite powders indicate that the interfaces of the TiB2-Al2O3 bond well, without any interfacial reaction products. It is proposed that the good interfacial bonding of the composite powders can be resulted from the TiB2 particles crystallizing and growing on the Al2O3 particles surface with surface defects acting as nucleation centers. 相似文献
17.
Sol-gel derived bismuth cerium titanate (BCT) thin films with different Bi contents in precursor solutions were deposited
on the Pt/Ti/SiO2/Si substrates. The effect of Bi content in the precursor solutions on the microstructure and ferroelectric properties of
the films was investigated. It is found that with Bi content increasing from 90% to 110% of the nominal value in the precursor
solutions, the dissipation factor and leakage current density of the BCT films obtained decrease, while the grain sizes, dielectric
constant and remanent polarizations (2Pr) increase, and concurrently, a Bi-deficient phase of Bi2Ti2O7 gradually disappears. The film prepared from solution with 110% of the nominal Bi content exhibits pure Bi-layered Aurivillius
polycrystalline phase, and the 2Pr value and coercive field value are 67.1 μC/cm2 and 299.7 kV/cm, respectively. Their dielectric constant and the dissipation factor are about 172 and 0.033 at 1 kHz, respectively.
Moreover, this film shows no polarization fatigue after 4.46×109 switching cycles.
Supported by the Hubei Province Natural Science Foundation (Grant No. 2007ABA309) 相似文献
18.
Luminescent properties of BaO-La2O3-B2O3 glasses with dopant 总被引:4,自引:0,他引:4
The luminescent properties of glasses synthesized in air atmosphere by conventional high temperature process were stud{ed. The emissions spectra of Eu^2 and Eu^3 were observed in BaO-La2O3-B2O3-Eu2O3 glasses.The results show that the broad emission peaks at 430 nm correspond to 5d→4f emission transition of Eu^2 , the sharp emission peaks at 592, 616, 650 and 250 nm correspond to 5^D0→1Fj(j=1--4) emission transition of Eu^3 ,respectively, which indicates that the BaO-La2O3a-B2O3-Eu2O3 glass can convert ultraviolet and green omponents of sunlight into blue and red light so as to increase the intensity of blue and red light, respectively. The luminescent in--tensity of Eu^2 increases with increasing the molar ratio of Tb^3 in BaO-La2O3-B2O3-Eu2O3a-Tb4O3 glasses, whereas the luminescent intensity of Eua^3 decreases. So the luminescent intensity of Eu(Ⅲ,Ⅱ) is influenced by Tb^3 .These phenomena can be explained by electron transfer mechanism; Eu^3 (4f6) Tb^3 (4f^8)→Eu^2 (4f′) Tb^4 (4f′). Taking advantage of the luminescent properties of BaO-La2O3-B2O3-Eu2O3 glasses, light-conversion glass for agriculture can be produced. 相似文献
19.
铜、银、金铟硒半导体薄膜光电化学振荡行为比较 总被引:1,自引:0,他引:1
对用电沉淀方法制备的铜铟硒,银铟硒和金铟硒半导体薄膜在阴极还原H2O2时产生的(光)电化学振荡现象进行了对比性的分析与研究,特别是对它们的振荡形式,起振条件,外界影响因素及光电调制等进行了阳纳,较系统地总结了IB族元素与In,Se的构造的三元半导体化合物薄膜的电化学振荡的基本特点。 相似文献