Determination of road dust loadings and chemical characteristics using resuspension

The contribution of fugitive dust from traffic to air pollution can no longer be ignored in China. In order to obtain the road dust loadings and to understand the chemical characteristics of PM₁₀ and PM_2.5 from typical road dust, different paved roads in eight districts of Beijing were selected for dust collection during the four seasons of 2005. Ninety-eight samples from 28 roads were obtained. The samples were resuspended using equipment assembled to simulate the rising process of road dust caused by the wind or wheels in order to obtain the PM₁₀ and PM_2.5 filter samples. The average road dust loading was 3.82 g m^− 2, with the highest of 24.22 g m^− 2 being in Hutongs in the rural–urban continuum during winter. The road dust loadings on higher-grade roads were lower than those on lower-grade roads. Attention should be paid to the pollution in the rural–urban continuum areas. The sums of element abundances measured were 16.17% and 18.50% for PM₁₀ and PM_2.5 in road dust. The average abundances of OC and EC in PM₁₀ and PM_2.5 in road dust were 11.52%, 2.01% and 12.50%, 2.06%, respectively. The abundance of elements, water-soluble ions, and OC, EC in PM₁₀ and PM_2.5 resuspended from road dust did not change greatly with seasons and road types. The soil dust, construction dust, dust emitted from burning coal, vehicle exhaust, and deposition of particles in the air were the main sources of road dust in Beijing. Affected by the application of snow-melting agents in Beijing during winter, the amount of Cl⁻ and Na⁺ was much higher during that time than in the other seasons. This will have a certain influence on roads, bridges, vegetations, and groundwater.     

Anthropogenic pollution and variability of manganese in alluvial sediments of the Yellow River,Ningxia, northwest China

Heavy metal pollution of sediments is a global concern and can be a serious problem in heavily industrialized parts of the world. Pollution by manganese is particularly common due to its ubiquitous natural occurrence, ease of mobilization, and extensive association with industry. In Ningxia, China, manganese pollution of Yellow River alluvial sediments was assessed by comparing manganese concentrations in 35 sediment samples with background values derived from similar sediments obtained at sites considered remote from potential sources of contamination. Natural background values of manganese were found to range from 192 to 323 mg/kg for surface sediments, and from 220 to 325 and 283 to 394 mg/kg for subsurface sediments at depths of 45–50 and 95–100 cm, respectively. In the study area, manganese content ranged from 565 to 1,363 mg/kg, indicating anthropogenic pollution extending to a depth of at least 1 m in the study area. All 35 samples were found to exceed the threshold effect concentration (TEC) of 460 mg/kg, below which adverse effects on sediment-dwelling organisms are not expected to occur, and one sample (T12) was found to exceed the probable effect concentration (PEC) of 1,100 mg/kg. PEC defines the threshold above which adverse effects are likely to be observed. Variogram analysis of the surface sediment manganese data revealed adherence to a Gaussian model, and ordinary kriging was used to generate a manganese distribution map. Analysis of the high nugget effect ratio indicates high, small-scale variations that are consistent with potential emissions from an adjacent electrolytic manganese plant.     

离子色谱检测在火电厂水汽品质监督中的应用

针对火力发电厂水汽品质,运用离子色谱分析技术进行查定。应用结果表明:离子色谱分析技术具有分析速度快、灵敏度高、结果准确的优点,对监督现场化学设备运行水平具有重要意义。     

Study of PCDD/Fs distribution in fly ash,ash deposits,and bottom ash from a medical waste incinerator in China

Over the past decades in China, the number of medical waste incinerators (MWIs) has been rising rapidly, causing emissions of polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs). In this study, samples of fly ash, ash deposits, and bottom ash from typical MWIs were analyzed for PCDD/Fs and their distribution characteristics. Results showed international toxic equivalent (I-TEQ) values in the range of 6.9–67 ng I-TEQ/g in fly ash and ash deposits, whereas the concentration in bottom ash was extremely low (only 1.33 pg I-TEQ/g), yet the generation of PCDD/Fs was mostly de novo synthesis in fly ash and ash deposits according to the ratio of PCDFs to PCDDs; the major distribution differences of PCDD/Fs in fly ash was manifested by the content of toxic furan 2,3,7,8-TCDF, but other toxic PCDD/Fs showed similar distribution. Other findings are that 2,3,4,7,8-PeCDF had the most contribution to TEQ concentration, and that the most abundant toxic furan congener is 1,2,3,4,6,7,8-HpCDF. Correlation analysis showed that there was no significant correlation between PCDD/Fs concentration and several other physical and chemical parameters.

Implications: This paper is of interest because it presents the emission performances of PCDD/Fs in ash from medical waste incineration in China. PCDD/F contents in fly ash and ash deposits vary between 6.9 and 67.3 ng I-TEQ/g. However, the concentration in bottom ash was extremely low (only 1.33?×?10^?3 ng I-TEQ/g). The fingerprints of PCDD/Fs in fly ash are almost similar, except for 2,3,7,8-TCDF. There is no marked correlation between PCDD/Fs and other physicochemical properties.

Supplemental Materials: Supplemental materials are available for this paper. Go to the publisher's online edition of the Journal of the Air & Waste Management Association.     

Distribution of polychlorinated dibenzo-p-dioxins and dibenzofurans in ambient air of different regions in China

Levels of polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs) were determined in fourteen ambient air samples collected in twelve cities of five provinces and one large municipality in China. The PCDD/F concentrations varied from 2.6 to 120 pg m⁻³ (or from 0.04 to 1.93 pg I-TEQ m⁻³). Generally, TCDF was the dominant homologue group and as a rule the homologue concentration of PCDF decreased with rising chlorine substitution number of PCDF. In all cases 2,3,4,7,8-PeCDF was the most important contributor to the I-TEQ value, accounting for 35–57% of the total I-TEQ value. Higher PCDD/F levels in ambient air were found during winter. The highest PCDD/F levels were found in Chengdu, Sichuan Province. In general, the PCDD/F levels in this study were in the same range as in other studies in China.     

气液两相滑动弧等离子体降解染料废水的研究

研究了气液两相滑动弧等离子技术对不同种类的可溶性染料废水的处理效果,考察了染料分子中的磺酸基数目、N=N双键数目、染料分子的不同主体结构等对染料降解效果的影响。结果表明,染料分子中的磺酸基数目越多,则染料的降解率越高;不论染料分子主体结构如何,氧化性物质可能均首先攻击分子中的发色基团,导致染料脱色;主体结构不同的染料混合时,可对COD的降解起到一定促进作用;染料分子中氯的取代位置不同,则脱氯率也不同,氯连接在直链或苯环上时较容易降解,而连接在均三嗪结构上时较难降解;从能量效率上考虑,气液两相滑动弧等离子体技术更适合降解高浓度的染料废水。     

长庆油田第三采油厂注水系统的管理

从油田注水对原油采收率提高的影响分析出发,总结了目前采三注水系统存在的问题,并从注水系统的管理着手,利用先进的科学技术和设备,优化注水处理工艺,提高处理效率,强化注水系统的维护,从设备的管理到一线岗位员工操作要求的规范,利用先进工艺技术提高联合站采出水处理能力,增强注水系统工作效率,使注水水质达到企业注水标准,保持原油上产。     

Mapping the cost risk of agricultural residue supply for energy application in rural China

This research aims to shed light on the interaction mechanism of cost risks for biomass material supply in power generation, especially for biomass-coal dual-fuel systems. Firstly, a game model is established to analyze interactions among factors including unit procurement cost, unit transportation cost, basic price and coal price for crop residue collection. Secondly, a Monte Carlo simulation is implemented to compare the profit increase under material competition with that under price alliance. The methodology is illustrated with a case study in a biomass power plant in Shandong Province, China. It shows that developing a price alliance will benefit both the allied enterprises and the local collection area in most circumstances. Thirdly, a risk tolerance area approach is applied in mapping the cost risk and in explaining the risky circumstances of the case study.     

UASB处理离子交换树脂生产废水的试验研究

本研究主要介绍，尝试采用UASB（Upflow Anaerobic Sludge Bed）反应器厌氧工艺处理某离子交换树脂生产废水试验。研究表明，在中温（37℃±1）环境下，容积负荷在6．0-7．0kgCODcr·m^-3·d^-1时，CODcr去除率维持在80％左右，运行稳定。本试验取得的试验效果，为以后的利用厌氧技术处理离子交换树脂生产废水提供了重要依据。     

湘西金矿溜矿井卸矿点尘源控制试验研究

通过对溜矿井卸矿点产尘及其特点的研究 ,提出了一种独特的防尘思维模式 ,并有针对地设计出一种自净式喷雾装置 ,适用效果良好。