应用S-T模型对沉积物中PAHs的生态风险分级评价

本文构建S-T模型,运用集对分析理论（set pair analysis）构建基本模型,采用层次分析法并参考毒性当量因子确定各指标权重,应用三角模糊数（triangular fuzzy number）对差异度系数进行改进,基于加拿大沉积物环境质量标准,对沉积物中多环芳烃进行生态风险分级评价.结果表明,该模型考虑到化合物之间的相互作用因素并做模糊处理,对差异度系数进行改进体现沉积物中多环芳烃生态风险等级标准的模糊性,为持久性有机污染物生态风险分级评价提供了一种简便客观有效的方法.     

Mercury flows in large-scale gold production and implications for Hg pollution control

Large-scale gold production(LSGP) is one of the five convention-related atmospheric mercury(Hg) emission sources in the Minamata Convention on Mercury. However, field experiments on Hg flows of the whole process of LSGP are limited. To identify the atmospheric Hg emission points and understand Hg emission characteristics of LSGP, Hg flows in two gold smelters were studied. Overall atmospheric Hg emissions accounted for 10%–17% of total Hg outputs and the Hg emission factors for all processes were 7.6–9.6 kg/ton. There were three dominant atmospheric Hg emission points in the studied gold smelters, including the exhaust gas of the roasting process, exhaust gas from the environmental fog collection stack and exhaust gas from the converter of the refining process. Atmospheric Hg emissions from the roasting process only accounted for 16%–29% of total emissions and the rest were emitted from the refining process. The overall Hg speciation profile(gaseous elemental Hg/gaseous oxidized Hg/particulate-bound Hg) for LSGP was 34.1/57.1/8.8. The dominant Hg output byproducts included waste acid, sulfuric acid and cyanide leaching residue. Total Hg outputs from these three byproducts were 80% in smelter A and 84% in smelter B. Our study indicated that previous atmospheric Hg emissions from large-scale gold production might have been overestimated.Hg emission control in LSGP is not especially urgent in China compared to other significant emission sources(e.g., cement plants). Instead, LSGP is a potential Hg release source due to the high Hg output proportions to acid and sludge.     

Relationship between PM10 and PM2.5 levels in high-traffic area determined using path analysis and linear regression

The objective of this study was to determine the relationship between PM_(10) and PM_(2.5) levels as related to meteorological conditions and traffic flow using both a linear regression analysis and a path analysis. The Particulate matter(PM) samples were collected from Sukhumvit road, Bangkok, Thailand, at both open(104 samples) and covered(92 samples)areas along the road. Fifteen percent of all samples were separated before the statistical models were run and used for model validation. The results from the path analysis were more elaborate than those from the linear regression, thus indicating that meteorological conditions had a direct effect on the particulate levels and that the effects of traffic flow were more variable in open areas. The model also indicated that meteorological conditions had an indirect effect and that traffic flow had a direct effect on particulate levels in covered areas. The model validation results indicated that for open areas, the R~2 values were not very different between the path analysis and the linear regression model, but that the path analysis was more accurate than the linear regression model at very low PM concentrations. At high PM concentrations, the path analysis model also had a better fit than did the linear regression, so the predictions from the path analysis model were more accurate than those from the linear regression.     

铜合金实验室试验与实海挂片结果的比较与分析

目的比较实验室试验结果与实海挂片结果对B10和H62两种铜合金腐蚀性能评价的异同之处。方法采用线性极化、电化学阻抗、显微形貌观察等,比较两种铜合金在实验室模拟海水中的的腐蚀速率、点蚀倾向,结合反应机理、腐蚀形貌、环境等外部因素,分析导致实验室与实海环境下出现差异的原因。结果除榆林海域外,实海挂片与实验室结果都表明,B10试样的平均腐蚀速率小于H62。B10和H62两种铜合金随温度升高腐蚀速率增大,在实验室和实海情况下表现出一致性,且平均腐蚀速率都随浸泡时间的延长而降低。结论在实海环境中,温度不是影响点蚀的主要因素,微生物等其他环境因素会对点蚀产生较大影响。     

某型飞机外翼5—8肋损伤原因分析及修复探讨

目的 分析某型飞机外翼5—8肋油箱区结构不同程度损伤的原因,制定修复方案。方法采用受载分析、有限元仿真计算、静力试验数据分析等强度计算方法分析损伤产生的原因,采用扫描电子显微镜和光学显微镜对磨痕形貌进行观测等失效分析,对损伤结构件开展失效模式分析,根据损伤原因及失效模式制定科学简便的修复方案,同时对损伤长桁采取的修补措施进行强度校核。结果 通过对外翼油箱充压破坏理论分析、有限元仿真计算、静力试验数据反推,并结合飞机实际损伤情况,得出油箱破坏理论分析危险薄弱部位与真实破坏情况一致的结论。有限元仿真计算最危险结构部位与实际结构首先发生破坏部位吻合,可作为深入制定修复方案及推测实际加载压力的依据。通过静力试验数据反推、结构实际损伤及有限元仿真计算结论得出,外翼5—8肋结构出现损伤时油箱施加压力约0.5 MPa,针对损伤制定了更换外翼油箱内部第5—8肋损伤结构和贴补加强损伤长桁的修理方案,经结构强度校核,满足设计要求。结论 分析认为外翼5—8肋油箱区结构损伤原因为油箱压力超过设计值导致结构过载断裂,采用贴补加强修理损伤长桁和更换第5—8肋损伤结构的修复方案能够满足强度设计要求,可指导同类飞机类似结构损伤故障的原因分析和修理,提醒同类飞机维修人员在飞机维护时应关注外翼油箱压力超压问题。     

空间站控制力矩陀螺微振动测试技术

目的分析控制力矩陀螺的微振动扰动特性。方法通过获取陀螺连接点对结构的扰振力输出、关键部位的微振动响应来获取产品的微振动扰动特性,通过隔振的方式对外部环境的干扰进行隔离,进而降低测试的背景噪声,通过运用高精度测试传感器来实现微小扰动力信号、加速度信号的测量,利用结构有限元法及单点激励多点响应的模态分析方法校核系统刚度,进而确定测试频率范围是否满足需求。结果可同时获得空间站控制力矩陀螺连接点处的输出扰振力、质心处的输出扰振力合力、合力矩以及关键部位的微振动响应,可有效隔离外部干扰,扰振力背景噪声的时域信号最大值可控制在0.07 N以内,RMS值在0.02 N以内,加速度信号的时域背景噪声最大值可控制在1.5 mg以内,RMS值在0.1 mg以内。可识别微小扰振信号,加速度传感器分辨率为5×10-5 grms,力传感器的测量分辨率为1×10-2 N,力矩测量分辨率小于1×10-2 N·m。测试频带在320 Hz以内。结论满足型号需求,并投入型号使用。     

黔西南喀斯特地区红色风化壳的物源及元素迁移特征

南方喀斯特地区广泛分布着大量的红色风化壳,其成因及形成机制目前还存在争议。本文以贵州黔西南布依族苗族自治州泥凼石林的两处红色风化壳剖面(ND和YK)为研究对象,来探讨风化剖面上覆红土的物源问题,并计算其主、微量元素及稀土元素的迁移规律,认为本研究两处风化壳上覆红土为下伏基岩原位风化形成的,而且两剖面土壤均继承各自基岩的地球化学特征,并由于pH、风化强度等因素的影响表现出了元素迁移特征上的差异性。     

南昌市冬季大气PM2.5中重金属元素来源分析及健康风险评价

采集2015年南昌市冬季大气PM_(2.5)样品,利用电感耦合等离子体质谱仪(ICP-MS)测定样品中重金属(V、Mn、Cr、Co、Ni、Cu、Zn、Cd、Ba和Pb)的含量,分析重金属的分布特征和来源,并对重金属健康风险进行评价。结果表明:采样期间PM2.5浓度总平均值为(29.74±16.82)μg/m~3,其中省外办最高,武术学校最低;各重金属元素总体平均浓度从高到低次序为:ZnPbCuMnBaNiVCrCdCo。因子分析结果表明:PM_(2.5)中重金属元素的来源包括道路交通尘和冶金化工排放、机动车尾气以及混合源。健康风险评价结果显示:PM_(2.5)中Mn对人体健康存在非致癌风险,其他元素(Cr、Ba、Co、Pb、Cd、Cu、V、Zn、Ni)基本没有非致癌风险;Cr对人体有较明显的致癌风险,Cd、Ni和Co对部分年龄段的人群(尤其是成年人)存在一定的致癌风险。     

西安市文教区表层土壤中PAHs来源及风险分析

文教区土壤环境质量直接影响学生以及职工的身体健康。本研究应用高效液相色谱仪对采集的西安市文教区表层土壤样品中的16种优控多环芳烃(PAHs)进行含量检测,分析其组分特征、来源及健康风险。结果表明,西安市文教区表层土壤中∑PAHs含量为0.290~4.147μg/g,平均值为1.515μg/g,7种致癌多环芳烃的含量为0.079~2.093μg/g,均值为0.593μg/g,土壤PAHs污染较为严重。其中4环的高环PAHs为土壤PAHs污染的主要物质,平均占∑PAHs含量的40.72%。源解析结果表明西安市文教区表层土壤中PAHs主要来源于石油燃烧、煤及生物质等的不完全燃烧。终生癌症风险评价表明西安市文教区表层土壤中PAHs污染对其生活在周围的人群产生的终生致癌风险性较小,但71.4%的样点达到严重污染水平,产生的间接影响应引起足够重视。     

盐酸萘乙二胺比色法测定大气中硝基苯、苯胺浓度的改进

本文探讨了盐酸萘乙二胺比色方法测定大气中硝基苯、苯胺浓度的最佳反应条件,如酸度、试剂加入量、反应温度、反应时间等。简化了过滤、洗涤操作,精密度高、显色稳定。