Roles of semivolatile and intermediate-volatility organic compounds in secondary organic aerosol formation and its implication: A review

Secondary organic aerosol(SOA) is a very important component of fine particulate matter(PM_2.5) in the atmosphere. However, the simulations of SOA, which could help to elucidate the detailed mechanism of SOA formation and quantify the roles of various precursors, remains unsatisfactory, as SOA levels are frequently underestimated. It has been found that the performance of SOA formation models can be significantly improved by incorporating the emission and evolution of semivolatile and ...     

湖北省某钢铁厂工业区及周边铅污染调查

为了解湖北省某钢铁厂周边铅污染的现状,通过对钢铁厂工业区及其周边乡村的土壤、蔬菜、居民体内和排污渠污泥中铅元素含量的研究,其结果表明:钢铁厂周围的土壤、蔬菜、居民均受到了一定程度的铅等重金属元素的污染,其含量高于国家标准或正常范围;钢铁厂工业区周边土壤铅污染主要由于工业废气(烟尘)扩散沉降和废水灌溉引起;污染区人体尿样中铅元素含量(116～160 ng/mL)普遍超标,头发样(2.09～12.04 μg/g)基本正常,尿样比头发样更能显示铅等重金属元素在人体内的分布特征.     

Effects of feed-supplementation and hide-spray application of two sources of tannins on enteric and hide bacteria of feedlot cattle

Pathogenic bacteria attached to the hide or shed in the feces of cattle at slaughter can contaminate carcasses intended to be processed for human consumption. Therefore, new pre-harvest interventions are needed to prevent the carriage and excretion of foodborne pathogens in cattle presented to the processing plant. The objectives of this study were to examine the antimicrobial effects of hydrolysable tannin-rich chestnut and condensed tannin-rich mimosa extracts on bacterial indicators of foodborne pathogens when applied as a hide-intervention and as a feed additive to feedlot cattle. Water (control) or solutions (3 % wt/vol) of chestnut- and mimosa-extract treatments were sprayed (25 mL) at the left costal side of each animal to a 1000 cm² area, divided in four equal quadrants. Hide-swabs samples obtained at pre-, 2-min, 8-h, and 24-h post-spray application were cultured to enumerate Escherichia coli/total coliforms and total aerobic plate counts. In a second experiment, diets supplemented without (controls) or with (1.5 % of diet dry matter) chestnut- or mimosa-extracts were fed during a 42–day experimental feeding period. Weekly fecal samples starting on day 0, and rumen fluid obtained on days 0, 7, 21 or 42 were cultured to enumerate E.coli/total coliforms and Campylobacter. Tannin spray application showed no effect of treatment or post-application-time (P> 0.05) on measured bacterial populations, averaging 1.7/1.8, 1.5/1.6 and 1.5/1.7 (log₁₀ CFU/cm²) for E. coli/total coliforms, and 4.0, 3.4 and 4.2 (log₁₀CFU/cm²) in total aerobes for control, chestnut and mimosa treatments, respectively. Mean (± SEM) ruminal E. coli and total coliform concentrations (log₁₀ CFU/mL) were reduced (P< 0.01) in steers fed chestnut-tannins (3.6 and 3.8 ± 0.1) in comparison with the controls (4.1 and 4.2 ± 0.1). Fecal E. coli concentrations were affected by treatment (P< 0.01), showing the highest values (log₁₀ CFU/g) in fecal contents from mimosa-fed steers compared to controls (5.9 versus 5.6 ± 0.1 SEM, respectively). Total coliforms (log CFU/g) showed the highest values (P< 0.01) in feces from chestnut- and mimosa-fed steers (6.0 and 6.1 ± 0.1 respectively) in comparison with controls (5.7 ± 0.1). Fecal Campylobacter concentrations (log₁₀CFU/g) were affected by treatment (P< 0.05), day (P< 0.001) and their interaction (P< 0.01) with the controls having lower concentrations than chestnut- and mimosa-fed steers (0.4, 1.0, and 0.8 ± 0.3, respectively). It was concluded that under our research conditions, tannins were not effective in decreasing measured bacterial populations on beef cattle hides. Additionally, chestnut tannin reduced E. coli and total coliforms within the rumen but the antimicrobial effect was not maintained in the lower gastrointestinal tract. Further research is necessary to elucidate the possible antimicrobial effects of tannins at site-specific locations of the gastrointestinal tract in beef cattle fed high-grain and high-forage diets.     

APPLICATION OF GREY MODEL AND ARTIFICIAL NEURAL NETWORKS TO FLOOD FORECASTING1

The main focus of this study was to compare the Grey model and several artificial neural network (ANN) models for real time flood forecasting, including a comparison of the models for various lead times (ranging from one to six hours). For hydrological applications, the Grey model has the advantage that it can easily be used in forecasting without assuming that forecast storm events exhibit the same stochastic characteristics as the storm events themselves. The major advantage of an ANN in rainfall‐runoff modeling is that there is no requirement for any prior assumptions regarding the processes involved. The Grey model and three ANN models were applied to a 2,509 km² watershed in the Republic of Korea to compare the results for real time flood forecasting with from one to six hours of lead time. The fifth‐order Grey model and the ANN models with the optimal network architectures, represented by ANN1004 (34 input nodes, 21 hidden nodes, and 1 output node), ANN1010 (40 input nodes, 25 hidden nodes, and 1 output node), and ANN1004T (14 input nodes, 21 hidden nodes, and 1 output node), were adopted to evaluate the effects of time lags and differences between area mean and point rainfall. The Grey model and the ANN models, which provided reliable forecasts with one to six hours of lead time, were calibrated and their datasets validated. The results showed that the Grey model and the ANN1010 model achieved the highest level of performance in forecasting runoff for one to six lead hours. The ANN model architectures (ANN1004 and ANN1010) that used point rainfall data performed better than the model that used mean rainfall data (ANN1004T) in the real time forecasting. The selected models thus appear to be a useful tool for flood forecasting in Korea.     

强化林火扑救力度实施林场有偿扑火

分析了新形势下单纯依赖专业森林消防队伍扑救森林火灾的不足与问题，提出了有偿扑火构想与保证措施。     

劳动者职业卫生保护权利及其保障体系(上)

2002年5月1日,《职业病防治法》正式实施。《职业病防治法》的立法宗旨和核心内容是保护劳动者的健康及其相关权益。劳动者职业卫生保护权利劳动者的职业卫生保护权利,是指劳动者在就业或者从事职业活动中为了保护自身健康不受职业病危害,有权作为或者不作为的行为,也包括要求用人单位作为或者不作为的行为。根据职业病防治法第三十六条规定,劳动者享有以下职业卫生保护权利: (一)接受职业卫生教育、培训的权利劳动者有权要求用人单位对其进行上     

架空管道震害预测实用方法的研究

根据震害调查分析和试验研究结果,建立了由环境因素和管道结构参数组成的,对架空管道震害预测进行二级多因素模糊综合评判的方法。文中给出了计算、评价构成二级评判因素地震烈度、场地类型、工作状态和结构种类各档次正态模糊数范数ａｋ的参数和对实际情况如何确定的方法。本文为面广量大的已建架空管道的震害预测工作提供了一套科学性强,方便实用的计算方法。     

日本城市化中的耕地变动与经验

日本是一个国土面积狭小、耕地资源稀缺的国家。然而，在人均土地资源极为有限的条件下，日本在较短时间内达到了高度城市化，同时付出了较小的用地代价。在其整个城市化进程中，日本还出现了三个耕地面积增长时期。尽管各时期增长原因不尽相同，但却反映出耕地面积变动与城市化发展的密切关系。事实表明，日本选择了一条节约有限土地资源的城市化发展道路，这些经验对我国城市化发展中的耕地利用与保护有积极的借鉴意义。     

Effect of surfactants on solubilization and degradation of phenanthrene under thermophilic conditions

The bioavailability and biodegradation of polycyclic aromatic hydrocarbons (PAHs) can be increased through the addition of surfactants. Previous studies of this nature have been conducted under mesophilic conditions. Hence, the aim of the present study was to investigate the effects of synthetic surfactants and biosurfactants on solubilization and degradation of phenanthrene (PHE) in a series of batch solution experiments under thermophilic conditions. Tween 80, Triton X-100, and biosurfactants produced from Pseudomonas aeruginosa strain P-CG3 (P-CG3) and Pseudomonas aeruginosa ATCC 9027 (P. 9027) were used in this study. Surfactants effectively enhanced the solubility of PHE at 50 degrees C and the biosurfactant from P-CG3 was most effective with a 28-fold increase in apparent solubility of PHE at a concentration of 10 x critical micelle concentration (CMC) compared with the controls. However, addition of synthetic surfactants or biosurfactants inhibited the biodegradation of PHE in mineral salts medium by an isolate Bacillus sp. B-UM. Degradation of PHE diminished with increasing surfactant concentrations, and PHE degradation was completely inhibited for all the surfactants tested when the concentrations were greater than their respective CMC. The growth test suggested that Tween 80 and biosurfactants were degradable, but preferential utilization of these surfactants as substrates was not the mechanism for explaining the inhibition of PHE biodegradation. Because of the hydrophobic property of B-UM, degradation inhibition of PHE by surfactants was probably due to the reduction of direct contact between bacterial cells and PHE.