水体中苯胺光降解的实验研究

为了更好地了解苯胺类物质在环境中的化学行为,在自行设计的光化学反应器上进行模拟天然水体的苯胺光降解实验,用气相色谱法测定苯胺的残余质量浓度,考察了水体pH值、光强、反应时间、光敏化剂、水质等条件影响下苯胺的光降解效果和规律.3h内苯胺在3个不同体系中的降解效果从大到小依次是:去离子水模拟天然水体、加入光敏化物质的灭菌河水、未加光敏化物质的灭菌河水.pH值为5.0,Fe2 、过氧化氢、腐殖质存在时苯胺的光降解效果较好.     

Seasonal and diurnal variations of atmospheric peroxyacetyl nitrate, peroxypropionyl nitrate, and carbon tetrachloride in Beijing

Atmospheric peroxyacetyl nitrate(PAN), peroxypropionyl nitrate(PPN), and carbon tetrachloride(CCl4) were measured from September 2010 to August 2011 in Beijing. PAN exhibited low values from mid-autumn to early spring(October to March) with monthly average concentrations ranging from 0.28 to 0.73 ppbV, and increased from early spring to summer(March to August), ranging from 1.37–3.79 ppbV. The monthly variation of PPN was similar to PAN, with low values(below detection limit to 0.18 ppbV) from mid-autumn to early spring, and a monthly maximum in September(1.14 ppbV). The monthly variation of CCl4was tightly related to the variation of temperature, exhibiting a minimum in winter(69.3 pptV) and a maximum of 180.6 pptV in summer. Due to weak solar intensity and short duration, PAN and O3showed no distinct diurnal patterns from morning to night during winter, whereas for other seasons, they both exhibited maximal values in the late afternoon(ca. 15:00 to 16:00 local time) and minimal values during early morning and midnight. Good linear correlations between PAN and PPN were found in autumn(R = 0.91), spring(R = 0.94), and summer(R = 0.81), with slopes of 0.130, 0.222, and 0.133, respectively, suggesting that anthropogenic hydrocarbons dominated the photochemical formation of PANs in Beijing. Positive correlation between PAN and O3 in summer with the low slopes( O3 / PAN) ranging from 9.92 to 18.0 indicated serious air pollution in Beijing, and strong negative correlation in winter reflected strong O3consumption by NO titration and less thermal decompositin of PAN.     

Origin of major ions in monthly rainfall events at the Bamenda Highlands, North West Cameroon

Rainwater characteristics can reveal emissions from various anthropogenic and natural sources into the atmosphere. The physico-chemical characteristics of 44 monthly rainfall events （collected between January and December 2012） from 4 weather stations （Bamenda, Ndop plain, Ndawara and Kumbo） in the Bamenda Highlands （BH） were investigated. The purpose was to determine the sources of chemical species, their seasonal inputs and suitability of the rainwater for drinking. The mean pH of 5 indicated the slightly acidic nature of the rainwater. Average total dissolved solids （TDS） were low （6.7 mg/L）, characteristic of unpolluted atmospheric moisture/air. Major ion concentrations （mg/L） were low and in the order K＋ 〉 Ca2＋ 〉 Mg2~ 〉 Na＋ for cations and NO3 〉〉 HCO3 〉 SO] 〉 CI- 〉 PO3- 〉 F- for anions. The average rainwater in the area was mixed Ca-Mg-SO4-CI water type. The CI-/Na＋ ratio （1.04） was comparable to that of seawater （1.16）, an indication that N a＋ and CI originated mainly from marine （Atlantic Ocean） aerosols. High enrichments of Ca2＋, Mg2＋ and SO2- to Na＋ ratios relative to seawater ratios （constituting 44% of the total ions） demonstrated their terrigenous origin, mainly from Saharan and Sahelian arid dusts. The K＋/Na＋ ratio （2.24）, which was similar to tropical vegetation ash （2.38）, and NO3 was essentially from biomass burning. Light （〈 100 mm） pre-monsoon and post-monsoon convective rains were enriched in major ions than the heavy （〉 100 mm） monsoon rains, indicating a high contribution of major ions during the low convective showers. Despite the acidic nature, the TDS and major ion concentrations classified the rainwater as potable based on the WHO guidelines.     

Characteristics of atmospheric particles and heavy metals in winter in Chang-Zhu-Tan city clusters, China

To understand the pollution characteristics of atmospheric particles and heavy metals in winter in Chang-Zhu-Tan city clusters, China, total suspended particulate(TSP) and PM10samples were collected in cities of Changsha, Zhuzhou and Xiangtan from December 2011 to January 2012, and heavy metals of Cd, Pb, Cr, and As were analyzed. It shows that the average TSP concentration in Changsha, Zhuzhou and Xiangtan were(183 ± 73),(201 ± 84) and(190 ± 66) μg/m3respectively, and the average PM10 were(171 ± 82),(178 ± 65) and(179 ± 55) μg/m3respectively. The lowest TSP and PM10concentrations occurred at the background Shaping site of Changsha. The average ratio of ρ(PM10)/ρ(TSP) was 91.9%, ranging from 81.3% to 98.9%. Concerning heavy metals, in TSP samples, the concentration of Cr, As, Cd and Pb were 28.8–56.5, 18.1–76.3, 3.9–26.1 and 148.0–460.9 ng/m3, respectively, while in PM10samples, were 16.4–42.1, 15.5–67.9, 3.3–22.2 and 127.9–389.3 ng/m3, respectively. The enrichment factor of Cd was the highest, followed by Pb and As, while that of Cr was the lowest.     

焦炉排放多环芳烃与人体健康风险评价研究

焦炉炼焦产生多环芳烃物质(PAHs)具有较强毒性和致癌作用,本研究以某大型钢铁企业焦炉为例,采用AERMOD扩散模式来预测分析焦炉排放PAHs共13种污染物在大气中迁移扩散情况,采用BREEZE Risk Analyst根据人体健康风险评价导则HHRAP计算评价范围内受体人群PAHs污染物致癌和危害指数,对焦炉排放PAHs的健康风险进行了定量评价.结果表明,应重点关注焦炉排放萘危害指数值影响(最大值为0.97).焦炉排放各污染物单因子致癌风险均小于1.0E-06,而综合考虑多环芳烃总致癌风险值最大达到2.65E-06,对当地居民的人体健康可能存在一定的影响.     

2012年春季京津冀地区一次沙尘暴天气过程中颗粒物的污染特征分析

本研究表征了2012年春季一次沙尘暴天气过程中京津冀地区大气可吸入颗粒物(PM10)的污染特征.借助PM10的水溶性元素、有机碳和元素碳的浓度,分析推断沙尘暴天气过程中矿物气溶胶对城市气溶胶污染的交汇叠加作用.使用中流量大气颗粒物采样器,于2012年4月1日～5月24日,在北京市西三环、天津空港经济区和张家口火车南站附近同时采集可吸入颗粒物(PM10),采用离子色谱和元素碳/有机碳分析仪分析获取其水溶性离子、元素碳和有机碳浓度.结果表明,采样期间北京、天津和张家口这3个采样点PM10质量浓度的日均值分别为233.82、279.64和238.13μg·m-3.4月27～29日,3个地区发生了沙尘暴天气,PM10质量浓度的最大日均值分别达755.54、831.32、582.82μg·m-3.沙尘暴期PM10的有机碳(OC)浓度、二次有机碳(SOC)/OC的比值、硝酸根(NO-3)和硫酸根(SO2-4)浓度均高于非沙尘暴期间.采用电荷平衡计算证明沙尘暴期间大气颗粒物表明呈碱性,说明外来沙尘暴与本地污染相互叠加,矿物元素改变了颗粒物表面的酸碱性,沙尘暴和有机物发生耦合,促进了二次有机物的转化.     

45~#钢在西双版纳大气环境下的腐蚀研究

目的研究西双版纳热带雨林地区大气环境下材料的初期腐蚀行为。方法使用45#碳钢在西双版纳大气环境下进行1年的大气暴露腐蚀试验,并利用质量损失分析、SEM、XRD和FTIR等技术,分析45#碳钢在西双版纳大气环境下暴露1年的腐蚀行为。结果 45#碳钢的腐蚀产物以γ-FeOOH,Fe(OH)3和Fe3O4为主,并有少量的α-FeOOH。结论西双版纳大气环境腐蚀性为C2级。在暴露1年的时间内,锈层化学稳定性随试验时间的延长逐渐增强,对基体的保护性逐渐加大。     

基于CALPUFF模型的漳州市大气环境容量研究

研究表明：CALPUFF模式是运用于广域的大气扩散模型,在区域范围较大的复杂地形条件下的应用具有突出的优势.利用CALPUFF大气扩散模型模拟漳州市2009年气象场和污染物浓度场,采用监测值对模拟结果进行验证表明模型的适用性;基于现状污染源,建立大气污染物传递系数矩阵,结合线性优化法测算了不同环境空气质量标准下漳州市大气环境容量.     

西安市PM_(2.5)污染源位置确定的模型应用研究

针对空气中PM2.5污染物的传播问题,以西安市的情况为实例,合理考虑风力等天气和季节因素的影响,建立能够刻画该地区PM2.5的发生和演变规律的有风高斯点源扩散数学模型,代入相关数据后,利用MATLAB软件求解出PM2.5污染源由一区扩散到另一区的浓度,最后由综合的各区总浓度得出PM2.5污染源的位置,并与该市实际检测到PM2.5数据进行对比分析。结果表明,确定的位置比较准确,该方法能为城市污染治理提供参考。     

大气降水中重金属离子特征研究

大气降水中重金属离子的研究可以反映大气污染、地表水污染的信息.通过对国内外大气降水中重金属研究现状的阐述和大气降水中重金属的来源进行理论分析,并利用实地大气降水采样分析,归纳出其中重金属的特征,监测当前大气的污染状况,从而为区域性的大气中重金属的污染评价及污染治理提供理论依据.降水中的重金属元素主要包括Pb、Mn、Zn、Cu、Cd、Cr等,通过分析测定可以为利用大气降水作为重要饮用水补给源的区域提供饮水安全保障.