Origin of high particle number concentrations reaching the St. Louis, Midwest Supersite

Ultrafine particles are associated with adverse health effects. Total Particle Number Concentration (TNC) of fine particles were measured during 2002 at the St. Louis — Midwest supersite. The time series showed overall low level with frequent large peaks. The time series was analyzed alongside criteria pollutant measurements and meteorological observations. Multiple regression analysis was used to identify further contributing factors and to determine the association of different pollutants with TNC levels. This showed the strong contribution of sulfur dioxide (SO₂) and nitrogen oxides (NO_x) to high TNC levels. The analysis also suggested that increased dispersion resulting from faster winds and higher mixing heights led to higher TNC levels. Overall, the results show that there were intense particle nucleation events in a SO₂ rich plume reaching the site which contributed around 29% of TNC. A further 40% was associated with primary emissions from mobile sources. By separating the remaining TNC by time of day and clear sky conditions, we suggest that most likely 8% of TNC are due to regional nucleation events and 23% are associated with the general urban background.     

Effect of liming on sulfate transformation and sulfur gas emissions in degraded vegetable soil treated by reductive soil disinfestation

Reductive soil disinfestation (RSD), namely amending organic materials and mulching or flooding to create strong reductive status, has been widely applied to improve degraded soils. However, there is little information available about sulfate (SO₄^2 −) transformation and sulfur (S) gas emissions during RSD treatment to degraded vegetable soils, in which S is generally accumulated. To investigate the effects of liming on SO₄^2 − transformation and S gas emissions, two SO₄^2 −-accumulated vegetable soils (denoted as S1 and S2) were treated by RSD, and RSD plus lime, denoted as RSD₀ and RSD₁, respectively. The results showed that RSD₀ treatment reduced soil SO₄^2 − by 51% and 61% in S1 and S2, respectively. The disappeared SO₄^2 − was mainly transformed into the undissolved form. During RSD treatment, hydrogen sulfide (H₂S), carbonyl sulfide (COS), and dimethyl sulfide (DMS) were detected, but the total S gas emission accounted for < 0.006% of total S in both soils. Compared to RSD₀, lime addition stimulated the conversion of SO₄^2 − into undissolved form, reduced soil SO₄^2 − by 81% in S1 and 84% in S2 and reduced total S gas emissions by 32% in S1 and 57% in S2, respectively. In addition to H₂S, COS and DMS, the emissions of carbon disulfide, methyl mercaptan, and dimethyl disulfide were also detected in RSD₁ treatment. The results indicated that RSD was an effective method to remove SO₄^2 −, liming stimulates the conversion of dissolved SO₄^2 − into undissolved form, probably due to the precipitation with calcium.     

一种新型河道复氧技术介绍——强曝气池

简要介绍了几种常见河道复氧技术,并以南淝河为例,详细阐述了强曝气池作为一种新型复氧技术的设计要点及运行效果。认为强曝气池复氧效果好,节省投资,运行管理方便,是一种值得推广的技术。     

油罐中油气爆炸规律研究

建立了油料储罐油气爆炸模拟实验系统,并在模拟实验的基础上,分析了不同因素对爆炸压力的影响及爆炸产物的分布规律.结果表明,油气浓度、罐内初始温度等对油罐油气混合物爆炸过程有重要影响,且存在临界油气浓度(2.5%)及临界初始温度(306 K),在临界值下,油气爆炸最为剧烈.当油气浓度小于临界浓度时,爆炸产物中CO2浓度高于CO浓度,而大于临界浓度时,爆炸产物中CO2浓度小于CO浓度.本研究可为油料储罐油气爆炸灾害事故的防治及安全规程的制定提供参考.     

贮罐区事故隐患分析及对策

通过对贮罐区组成、贮存物质的理化性质、不安全因素、贮罐区现状的调查,运用事故隐患分析的原理,对调查结果进行了分析,并根据治理隐患一般遵循的10项原则,提出了有针对性的防范对策.     

原油汽车罐车油罐爆炸事故原因分析及预防

以原油汽车罐车油罐爆炸事故为背景,通过分析这起事故的成因,提供了调查此起油罐爆炸的思路,并提出预防措施和对策.     

Studies on the origin of the methylsulfonyl‐containing metabolites from propachlor

Abstract

Metabolites in which the chlorine from propachlor has been replaced by a cysteine group or a methylsulfonyl group [‐S(O₂) CH₃] are present in the urine of rats dosed orally with propachlor. In the present study, urine from rats given single oral doses of ³⁵S‐labeled cysteine conjugate of propachlor contained metabolites having the methylsulfonyl groups labeled with S. No metabolites containing ¹⁴C‐labeled methylsulfonyl groups were isolated from urine of rats given single oral doses of the cysteine conjugate of propachlor in which the cysteine group was uniformly labeled with ¹⁴C. These findings show that the cysteine conjugate of propachlor is the source of sulfur in the methylsulfonyl‐containing metabolites. Therefore, we suggest that a C‐S lyase present in the animal cleaves the cysteine conjugate of propachlor and thus allows further metabolism of the sulfur to a methylsulfonyl moiety.     

高炉贮矿槽除尘系统的设计与分析

文章以河南青浦合金材料有限公司2座580m^3高炉贮矿槽除尘共用一台1450m^2的长袋低压脉冲袋式除尘器的总体设计方案为例,结合实践分析了高炉贮矿槽除尘系统的特点,总结并改进了整个除尘系统中的设计缺陷和制作结构,使该除尘系统得到了成功应用。     

油罐扬沸火灾防治模拟实验研究

分析扬沸火灾形成的3个基本物理条件,给出扬沸三角形的概念,提出通过破坏3个基本条件中任一条件来抑制扬沸火灾发生的构想。为解决其防治问题建立小尺度油罐扬沸火灾防治模拟实验台,用沸石和双列盘管式冷却法对扬沸火灾防治进行了实验研究;通过对比两种方法施加前后的油层、油水界面、水层温度和火焰辐射,发现双列盘管式冷却法和沸石能有效地抑制扬沸的形成和降低扬沸的危害程度。从机理上分析,小尺度油罐扬沸火灾的防治方法可为扬沸火灾的防治提供一定的理论依据。     

时变条件下公路危险品罐车运输路线选择

为合理选择公路运输危险品路线,保障运输安全,将用于求解静态路径规划问题的Diikstra标号法进行推广和改进,提出指标累积值标号法,运用该方法并依据危险品罐车运输事故统计数据,建立了时变条件下以路段泄漏事故率、路侧人口密度及路段运输费用为指标的危险品罐车公路运输路线选择模型.并给出待选路线对比原则.实例应用表明,该模型充分考虑了事故概率、事故后果及运输成本3大危险品运输路线选择影响因素,使用方便且受主观因素影响小,具有较好的实用性.