测定土壤中有机物前处理方法的探讨

根据铁岭市08年底土壤调查采集,利用现有大型仪器完成了土壤有杌物的全分析,使用仪器有气质联机,气相色谱（ECD、FID、FPD）,高效液相色谱等大型仪器。本文论述了三大类有机物的前处理方法,根据各种有机物的特性,选择了较好的前处理方法和条件,为应用大型仪器对土壤中有机物的分析打下了良好的基础。     

热解吸气相色谱双通道检测空气中TVOC

探讨了通过气相色谱仪双通道检测室内空气中总挥发性有机化合物的可行性.建立了前、后双通道的苯、甲苯、乙酸丁酯、乙苯、苯乙烯、对(间)二甲苯、邻二甲苯、正十一烷等9种典型有机污染物的外标曲线,各组分相关系数R2为0.9995～1,并通过各自的标准曲线来计算其标样考核结果,对比标样真实浓度值,验证前、后双通道的准确性以及相互...     

Analysis of risk trade-off relationships between organic solvents and aqueous agents: case study of metal cleaning processes

When substance substitution is implemented to reduce the target risk of production processes, countervailing risks may occur. The goal of this study is to analyze the risk trade-off relationships between organic solvents and aqueous agents in the case study of metal cleaning processes. Global environmental impacts and local risks were evaluated for the eight scenarios by life cycle and risk assessments, respectively. The results show that the contribution of the processes using chlorinated solvents to photochemical ozone creation, human toxicity, ozone depletion, and ecotoxicity was larger than processes using aqueous detergents, while the contribution of aqueous processes to eutrophication was larger than chlorinated processes. Neighbors’ health risk around a cleaning site using chlorinated solvents was sufficiently small in all scenarios, whereas ecological risk due to surfactants which are contained in aqueous detergents and emitted to the local aquatic environment should be reduced. Cleansing agents and process facilities should be selected on the basis of the comprehensive analysis of risk trade-off relationships for feasible and cleaner production.     

Ordering phenomena in quasi-one-dimensional organic conductors

Low-dimensional organic conductors could establish themselves as model systems for the investigation of the physics in reduced dimensions. In the metallic state of a one-dimensional solid, Fermi liquid theory breaks down and spin and charge degrees of freedom become separated. But the metallic phase is not stable in one dimension: as the temperature is reduced, the electronic charge and spin tend to arrange themselves in an ordered fashion due to strong correlations. The competition of the different interactions is responsible for which broken-symmetry ground state is eventually realized in a specific compound and which drives the system toward an insulating state. Here, we review the various ordering phenomena and how they can be identified by optic and magnetic measurements. While the final results might look very similar in the case of a charge density wave and a charge-ordered metal, for instance, the physical cause is completely different. When density waves form, a gap opens in the density of states at the Fermi energy due to nesting of the one-dimension Fermi surface sheets. When a one-dimensional metal becomes a charge-ordered Mott insulator, on the other hand, the short-range Coulomb repulsion localizes the charge on the lattice sites and even causes certain charge patterns. We try to point out the similarities and conceptional differences of these phenomena and give an example for each of them. Particular emphasis will be put on collective phenomena that are inherently present as soon as ordering breaks the symmetry of the system.     

西安城区大气PM_(2.5)中有机碳与元素碳的污染特征

为研究西安市夏、秋、冬3季大气细颗粒物中碳组分的污染变化规律,于2013年夏、秋、冬3季在西安市明城墙内采集大气中的PM2.5样品,测定了样品中的有机碳和元素碳的含量。结果显示,PM2.5中OC和EC的季节平均浓度冬季最高,秋季次之,夏季最低。OC/EC的比值在夏、秋、冬3季均超过2.0,说明采样期间夏、秋、冬3季均存在二次污染。OC/PM2.5的比值夏秋两季差异较小,冬季明显高于夏秋两季;EC/PM2.5的比值在夏、秋、冬3季的变化不大。OC和EC的相关性:夏季秋季冬季。OC与PM2.5的相关程度冬季秋季夏季,且随季节更替变化明显;EC与PM2.5的相关性:秋季夏季冬季。即随着季节变化PM2.5浓度水平整体升高、污染加重时,PM2.5中的OC所占比例明显升高,EC比较稳定,说明受人为影响的二次排放为主要成分的OC对PM2.5贡献更大。     

盐结皮对土壤有机质和水分积累的影响

以喀什地区典型的盐结皮土壤为例,在不同厚度的盐结皮土壤区域采集不同深度的土壤样品。结果表明:盐结皮越厚的土壤区域,其各层土壤中的盐分含量越高,土壤有机质含量越低,土壤水分含量越高,由此说明,盐结皮不利于土壤有机质的积累,但是却起到一定的保水作用。     

Modeling of the venting of an untempered system under runaway conditions

The prediction of the consequences of a runaway reaction in terms of temperature and pressure evolution in a reactor requires the knowledge of the reaction kinetics, thermodynamics and fluid dynamics inside the vessel during venting. Such phenomena and their interaction are complex and yet to be fully understood, especially reactions where the pressure generation is totally or partially due to the production of permanent gases (gassy or hybrid systems). Moreover, these phenomena cannot be easily determined by laboratory scale experiments. In this paper, a dynamic model developed to simulate the behavior of an untempered reacting mixture during venting is presented. The model provides the temperature, pressure and mass inventory profiles before and during venting. A sensitivity study of the model was performed. This modeling work provides some insight regarding the interpretation of the data obtained from untempered system venting experiments. The outcome of this work contribute to improving the design of emergency relief systems for hybrid and gassy systems, where significant progress is still to be made in the experimental and modeling areas.     

Remediation effect of compost on soluble mercury transfer in a crop of Phaseolus vulgaris

We studied the dynamics of mercury (Hg) transfer in Phaseolus vulgaris plants grown in soil with Hg-doped compost at the maximum levels permitted by Colombian law on organic amendments. Quantitative evaluation of transfer was made in different plant organs: roots, stem, leaves, pods and seeds. Matrix effect was determined in doped soil assays, using soil with and without addition of compost. Results showed that the use of organic matter reduced Hg transfer to the plant and the amount transferred was differentially distributed to the organs. We observed an inverse relationship between concentration and distance from the body to the root. It was evident that transfer was mediated by quantitative factors; the greater the presence of mercury in soil, the larger the amount that will be transferred. Results also indicate the remedial effect of compost and the presence of a barrier, at the root level, against mercury translocation to the plant aerial parts.     

Effects of water regime, crop residues, and application rates on control of Fusarium oxysporum f. sp. cubense

Biological soil disinfestation is an effective method to control soil-borne disease by flooding and incorporating with organic amendments, but field conditions and resources sometimes limited its practical application. A laboratory experiment was conducted to develop practice guidelines on controlling Fusarium wilt, a widespread banana disease caused by Fusarium oxysporum f. sp. cubense(FOC). FOC infested soil incorporated with rice or maize straw at rates of 1.5 tons/ha and 3.0 tons/ha was incubated under flooded or water-saturated(100% water holding capacity) conditions at 30℃ for 30 days. Results showed that FOC populations in the soils incorporated with either rice or maize straw rapidly reduced more than 90% in the first 15 days and then fluctuated till the end of incubation, while flooding alone without organic amendment reduced FOC populations slightly. The rapid and dramatic decrease of redox potential(down to- 350 m V) in straw-amended treatments implied that both anaerobic condition and strongly reductive soil condition would contribute to pathogen inactivation. Water-saturation combined with straw amendments had the comparable effects on reduction of FOC, indicating that flooding was not indispensable for inactivating FOC. There was no significant difference in the reduction of FOC observed in the straw amendments at between 1.5 and 3 tons/ha. Therefore,incorporating soil with straw(rice or maize straw) at a rate of 3.0 tons/ha under 100%water holding capacity or 1.5 tons/ha under flooding, would effectively alleviate banana Fusarium wilt caused by FOC after 15-day treating under 30℃.     

Remediation effect of compost on soluble mercury transfer in a crop of Phaseolus vulgaris

We studied the dynamics of mercury (Hg) transfer in Phaseolus vulgaris plants grown in soil with Hg-doped compost at the maximum levels permitted by Colombian law on organic amendments. Quantitative evaluation of transfer was made in different plant organs: roots, stem, leaves, pods and seeds. Matrix effect was determined in doped soil assays, using soil with and without addition of compost. Results showed that the use of organic matter reduced Hg transfer to the plant and the amount transferred was differentially distributed to the organs. We observed an inverse relationship between concentration and distance from the body to the root. It was evident that transfer was mediated by quantitative factors; the greater the presence of mercury in soil, the larger the amount that will be transferred. Results also indicate the remedial effect of compost and the presence of a barrier, at the root level, against mercury translocation to the plant aerial parts.