Dry deposition of PM10 over the Yellow Sea during Asian dust events from 2001 to 2007

Dry deposition velocities and fluxes of PM10during Asian dust events over the Yellow Sea from 2001 to 2007 were investigated using observation data in Qingdao, China and Jeju, Korea. The dry deposition velocities of PM10 during dust events over the Yellow Sea ranged from 0.19 to 8.17 cm/sec, with an average of 3.38 cm/sec. Dry deposition fluxes of PM10during dust events over the Yellow Sea were in the range of 68.5–2647.1 mg/(m2·day), with an average of 545.4 mg/(m2·day), which is 2–10 times higher than those reported by other studies for both dust and non-dust periods. It was estimated that 2.6 × 1011–48.7 × 1011g dust particles deposit to the Yellow Sea during dust events through dry deposition every year. Compared with the results in previous studies, it was found that the dry deposition of PM10over the Yellow Sea during dust events in the years with high frequency of dust could account for a large or overwhelming fraction of the annual total dry deposition. Backward air mass trajectory analysis showed that dust events influenced Jeju mainly originated from the desert regions located in Mongolia and Inner Mongolia, China. There were 119 backward trajectories influenced both Qingdao and Jeju during 15 dust events from 2001 to 2007, accounting for 61.3% of the total trajectories of 194, indicating that Qingdao and Jeju were usually on the same pathway of dust transport downwind from source areas.     

Evaluation of Bacillus sp. MZS10 for decolorizing Azure B dye and its decolorization mechanism

To evaluate decolorization and detoxification of Azure B dye by a newly isolated Bacillus sp. MZS10 strain, the cultivation medium and decolorization mechanism of the isolate were investigated. The decolorization was discovered to be dependent on cell density of the isolate and reached 93.55%(0.04 g/L) after 14 hr of cultivation in a 5 L stirred-tank fermenter at 2.0 g/L yeast extract and 6.0 g/L soluble starch and a small amount of mineral salts. The decolorization metabolites were identified with ultra performance liquid chromatography-tandem mass spectroscopy(UPLC-MS). A mechanism for decolorization of Azure B was proposed as follows: the C=N in Azure B was initially reduced to –NH by nicotinamide adenine dinucleotide phosphate(NADPH)-dependent quinone dehydrogenase, and then the –NH further combined with –OH derived from glucose to form a stable and colorless compound through a dehydration reaction. The phytotoxicity was evaluated for both Azure B and its related derivatives produced by Bacillus sp. MZS10 decolorization, indicating that the decolorization metabolites were less toxic than original dye. The decolorization efficiency and mechanism shown by Bacillus sp. MZS10 provided insight on its potential application for the bioremediation of the dye Azure B.     

Removal of phenol from aqueous solution by adsorption onto OTMAC-modified attapulgite

The potential of octodecyl trimethyl ammonium chloride (OTMAC)-modified attapulgite (AT) for phenol adsorption from aqueous solutions was studied. The comparison of natural AT and modified AT showed that it is possible to utilize the sonication-modified OTMAC-AT in the treatment of phenol-contaminated wastewaters. Batch sorption studies were carried out to evaluate the effect of contact time, shaking frequency, temperature and the amount of AT. The results showed that in a lab-scale reactor, at room temperature, with an amount of the modified AT added (2.5 g), and a shaking frequency of 140 rev/min, the adsorption rate of phenol could be 60.4% for a duration of 60 min. The sorption kinetics were described by a pseudo-second-order model, and the values of k and q(e) were 1.367 mg/ig min and 0.7901 ig/mg, respectively. The analysis of equilibrium data showed that the Freundlich isotherms were found to be applicable for the adsorption equilibrium data. K and 1/n were estimated to be 14.53 and 0.8438, respectively.     

应用区间层次分析法(IAHP)研究高层建筑火灾安全因素

高层建筑物的火灾安全影响因素繁多,其对建筑物火灾安全性的影响不容易确定,采用传统的层次分析法对某些因子的影响权重进行确定时难度较大.本文采用区间层次分析法来解决这一问题.首先建立影响高层建筑火灾安全的层次分析模型,然后用区间层次分析法确定影响因子,采用区间数特征根法求出各个火灾安全因子的权重值,并进行一致性检验.研究表明,影响高层建筑火灾安全的因子从大到小依次为:安全疏散措施、管理与维护、消防设施、报警与灭火系统、阻燃与防火结构,得到了每个因子的权重.采用同样的方法确定了每个影响因子的子因子的权重及重要性排序.其结果与实际情况基本相符.表明在进行高层建筑火灾安全性评估时,区间层次分析法是一种较好的方法.     

体育赛场人群疏散过程滞留人数定量模型研究

体育赛场历史事故统计分析表明,出口堵塞为导致人群拥挤踩踏事故发生的主要原因.滞留人群是疏散过程最常见的一种人流形式,同时也是拥挤踩踏事故风险的主要承载体.基于人群流量与人群密度关系建立了体育赛场时间维变量的滞留人数定量模型.体育赛场看台不同宽度出口人群疏散计算结果表明,滞留人数不仅对人群疏散时间有直接影响,而且与事故发生概率之间存在一定的关系.该模型可用于指导体育赛场出口设计,疏散路线选择及应急预案的编制等.     

以pH和ORP作为脉冲SBR工艺的实时控制参数

为了实现脉冲SBR深度脱氮的实时控制,以某污水处理厂市政污水为处理对象,考察了脉冲SBR在深度脱氮过程中pH及ORP的变化规律.试验结果表明,pH及ORP的变化规律与脉冲SBR有机物去除、硝化与反硝化过程存在较好的相关关系.可以根据pH和ORP变化曲线上的特征点对脉冲SBR进行实时控制.并考察了污水C/N(COD/NH4 -N)对pH及ORP的变化规律的影响.在硝化过程中,C/N对pH及ORP曲线变化点的出现没有影响;在反硝化过程中,应结合pH值"硝酸盐峰"和ORP"硝酸盐膝"来判断低C/N污水反硝化的终点.在该试验中,出水TN低于2 mg/L,TN去除率可达到96%以上.     

Birth outcomes of infants born in areas with elevated ambient exposure to incinerator generated PCDD/Fs

The purpose of this study was to determine if elevated ambient exposure to incinerator generated polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs) may affect birth outcomes of exposed infants born in Taipei metropolitan areas, Taiwan. The relationships between exposure to elevated PCDD/Fs concentration and various birth outcomes including birth weight, gestational age, and proportion of females were cross-sectionally assessed in 1991 (one year before the incinerator started to operate) and 1997 (five years later), respectively. We used the US EPA Industrial Source Complex Model-Sort Term modeling technique to determine the ambient PCDD/Fs concentrations in the study areas, in which 40 districts with annual averaged PCDD/Fs exposure of > or = 0.03 pg TEQ/m3 were considered as the exposed areas and another 40 districts with an estimated concentration of zero were randomly selected as reference areas. Information on birth outcomes was retrieved from the Taiwan's Birth Registry. A total of 6697 and 6282 neonates were included in the analysis for 1991 and 1997, respectively. After controlling for potential confounders, the results showed that the odds ratios (ORs) of low birth weight (< 2500 g) for higher exposures were 0.94 (> 0.05 pg TEQ/m3) and 091 (0.03-0.05 pg TEQ/m3) in 1991 and were 1.07 (> 0.05 pg TEQ/m3) and 1.06 (0.03-0.05 pg TEQ/m3) in 1997. The corresponding ORs were 1.05/0.86 (1991) and 1.12/1.22 (1997) for preterm (< 37 completed weeks of gestation), as well as 0.95/1.00 (1991) and 0.95/0.90 (1997) for female births. The above ORs were all close to unity and were statistically insignificant. When birth weight was analyzed as a continuous variable, the difference in mean birth weight between exposed group (> 0.03 pg TEQ/m3) and reference group decreased from 3.02 g in 1991 to -5.87 g in 1997. Analysis of continuous data also showed that the mean difference in gestational age between exposed and reference areas decreased from 0.05 weeks in 1991 to -0.09 week (p<0.05) in 1997. This study tends to conclude that the incinerator generated dioxin poses little effects on birth weight and female birth, but might pose small effects on gestational age. If the observed adverse effects turn out to be real, the measures now taken for improvement of abatement of waste gases seem to be a wise thing to do.     

Attack vulnerability of self-organizing networks

There are several self-organizing networks in the real world, and these networks severely affect the development of the modern society. This paper investigates the vulnerability of self-organizing networks subject to malicious attacks according to a new framework. Assuming the initial load of node i as L_i=αk_i+(1-α)∑_j∈Γik_j with k_i and Γ_i being the degree and the set of neighbor nodes of the node i, where α is a tunable parameter and control the strength of the initial loads of nodes. The node with the maximum degree is considered as the attacked node, and with the changes of the parameter α, cascading failures will be investigated in this paper. Local redistribution rule has been adopted to study the cascading breakdowns of the US power grid and IEEE-118 networks. Additionally, the capacity of the node i is defined as C_i = (1 + β)L_i, the critical threshold β_c of the US power grid and IEEE-118 networks will be obtained from the evolutional process of cascading failures. Finally, an optimal design of US power grid network is given in this paper.     

Comparing forest fragmentation and its drivers in China and the USA with Globcover v2.2

Forest loss and fragmentation are of major concern to the international community, in large part because they impact so many important environmental processes. The main objective of this study was to assess the differences in forest fragmentation patterns and drivers between China and the conterminous United States (USA). Using the latest 300-m resolution global land cover product, Globcover v2.2, a comparative analysis of forest fragmentation patterns and drivers was made. The fragmentation patterns were characterized by using a forest fragmentation model built on the sliding window analysis technique in association with landscape indices. Results showed that China’s forests were substantially more fragmented than those of the USA. This was evidenced by a large difference in the amount of interior forest area share, with China having 48% interior forest versus the 66% for the USA. China’s forest fragmentation was primarily attributed to anthropogenic disturbances, driven particularly by agricultural expansion from an increasing and large population, as well as poor forest management practices. In contrast, USA forests were principally fragmented by natural land cover types. However, USA urban sprawl contributed more to forest fragmentation than in China. This is closely tied to the USA’s economy, lifestyle and institutional processes. Fragmentation maps were generated from this study, which provide valuable insights and implications regarding habitat planning for rare and endangered species. Such maps enable development of strategic plans for sustainable forest management by identifying areas with high amounts of human-induced fragmentation, which improve risk assessments and enable better targeting for protection and remediation efforts. Because forest fragmentation is a long-term, complex process that is highly related to political, institutional, economic and philosophical arenas, both nations need to take effective and comprehensive measures to mitigate the negative effects of forest loss and fragmentation on the existing forest ecosystems.     

我国洪涝灾害规律的研究

系统地分析了我国洪灾形成的原因、时空上的规律以及现今防洪存在的一些问题, 最后提出了防洪减灾的若干对策