Trophic states of creeks and their relationship to changes in water level in Xixi National Wetland Park,China

Urban wetland parks are a new type of urban park that have developed rapidly in recent years and have caught the attention of multiple governmental departments. The objective of this paper was to describe the trophic states of creeks and their relationship to water levels in an urban wetland park in Xixi, China. The study was based on temporal and spatial data collected monthly between March 2009 and March 2010. The results indicated that: (1) water quality significantly changed from upstream to downstream in study creeks. From upstream to downstream, water quality of creeks I and III improved; however, the water quality of creek IV and V declined; (2) trophic states in Xixi creeks differed according to seasons. Overall, the nutrition in creeks was measured at the slight eutrophication level. Nutrition was highest in summer and lowest in winter; (3) the relationship between water quality and water level differed dramatically between creeks. Water quality and water level in creek I was significantly negatively correlated, while no obvious trends were observed in other creeks. In order to improve water quality in creeks, the valid technique is to strengthen the management of inflowing water quality and then control water levels.     

火工烟火职业事故特点及防范研究

火工烟火职业历来把安全工作放在日常工作的首位。然而安全工作不应该只局限在监督检查的陈规旧套之中，而应赋于它更科学更积极的内涵、本文通过对火工烟火系统危险性及其职业事故特点的分析，提出了可由计算机管理的控制安全的平台滚珠模型理论，强调了操作者的心理素质对安全工作的重要影响和作用。     

安全科学的研究对象与知识体系

在研讨安全科学和学科内涵若干论述的基础上,以科学、交叉科学、辩证唯物主义为指导,对安全科学的研究对象、安全科学的知识体系、安全科学综合理论体系的构成进行了表述。以大安全观为主线,给出了安全科学是以人们在生活、生产、生存领域的安全问题为研究对象;研究具有复杂的、巨系统特点的安全系统的结构,研究其由安全态如何突变、势垒跃迁转化为另一个安全态;研究消除或控制危害因素的理论和技术;研究如何控制和回避风险;研究安全观念和思维知识体系的一门交叉学科。特别阐明了安全科学研究对象的特殊性及其要揭示的特殊规律。试图确立安全科学的科学地位。     

组织安全文化的动力初探——行为基础安全

80%以上的事故都是由不安全行为引发的,提高人的安全行为将会大大提高安全的业绩.从安全文化的概念出发,通过讨论几种典型的安全文化模式得出安全文化的3个基本要素:组织因素、个人因素、行为因素.随着现代科技进步和组织管理体系的不断完善,个人和行为因素越发凸现.通过对行为基础安全方法的阐述和分析,概括出了行为基础安全促进安全文化的原因.行为基础安全的引进和实施将会大大提高组织的业绩和安全文化.     

CNG汽车加气站火灾爆炸危险分析与预防

对压缩天然气（CNG）汽车加气站的危险因素进行了辨识，并且用事故树法对加气站的火灾爆炸危险进行了分析，从技术、教育、管理3个方面提出了预防控制措施。     

危险货物道路运输事故统计分析

为掌握危险货物道路运输事故的发生规律,预防事故与灾害发生,笔者收集、整理了2000年9月至2007年3月间的609起危险货物道路运输事故案例,并对案例进行详细分解和统计分析,获得了危险货物道路运输事故的时间分布、地域分布、路段分布、事故形态分布、事故原因分布等统计特征。研究结果表明,危险货物道路运输事故具有如下规律:早晨和上午(4时至12时)是事故多发时段;事故形态以单车事故为主,特别是车辆倾斜或侧翻事故为数最多;驾驶员处置不当和违法驾驶行为以及运输车辆机件失效是导致事故的最主要的两类原因。针对案例分析结果,提出预防危险货物道路运输事故、保障危险货物道路运输安全的对策与建议。     

再论科学安全观

以科学发展观,辩证唯物主义与历史唯物主义为指导,以国际、国家社会发展为背景,综合各个领域提出的安全观,将安全观归纳为:宿命安全观、知命安全观、系统安全观和大安全观4种基本模式;提出以安全的社会价值和经济价值的认定为主体的安全价值观是安全观确立的基础,而构成安全观的人生价值观及人命价值观等是人生观乃至世界观的重要组成部分,是每个人实现人生价值观的保障。笔者试图以安全科学的基本理论统一人们对安全观的认识,旨在进一步充实完善安全学的学术内容。     

The growth and Cu and Zn uptake of pakchois (Brassica chinesis L.) in an acidic soil as affected by chicken or pig manure

In a pot experiment, pig manure (PM) and chicken manure (CM) were applied to an acidic soil at application rates of 2%, 4% and 8% (W/W) to evaluate their effects on the growth, Cu and Zn uptake and transfer of five cultivars of pakchoi (Brassica chinesis L.). The results showed that alkaline manures significantly increased the biomass of pakchois, and also pH and electrical conductivity of the soil. Both 0.01 M CaCl₂ and 1.0 M NH₄NO₃ salt solutions predict the Zn transfer from soil to pakchois well, but not for Cu. For the cultivar Siyueman, the transfer factors of Cu (or Zn) in the PM treatments were higher than that in the CM treatments. In our experiment the Cu and Zn concentrations in pakchois did not exceed the Chinese Food Hygiene Standard, but more attention should be paid to heavy metals risk on pakchois at lower soil pH and salt impairment by manures application.     

Influence of tetracycline exposure on the growth of wheat seedlings and the rhizosphere microbial community structure in hydroponic culture

In this study, the effects of tetracycline exposure on wheat growth and the microbial community structure in the rhizosphere were investigated under hydroponic culture conditions. Exposure to various concentrations of tetracycline resulted in significant suppression of the growth of wheat roots and shoots, with minimum doses of 0.8 mg L^?1 and 4 mg L^?1 resulting in inhibition rates of 32% and 15.4%, respectively. Complete inhibition of the growth of these two parts of wheat plants was observed in response to treatment with tetracycline at 20 mg L^?1 and 100 mg L^?1, respectively. However, the germination of wheat seeds was not sensitive to exposure to tetracycline. The effects of tetracycline exposure on the microbial community in the wheat rhizosphere were evaluated through traditional cultivation and molecular biological analyses. The cultivation results indicated that bacteria were the dominant population, being present in concentrations of 1× 10⁸–2.45× 10⁹CFUs mL^?1, although 39% to 87% inhibition occurred in response to tetracycline. The concentration of fungi increased in all tetracycline treated samples to 2.5 to 15.8 times that of the control. The highest concentration of fungi (4.27× 10⁸ CFU mL^?1) was observed in response to 60 mg L^?1 tetracycline after 15 days of cultivation. In this stage, a large amount of fungal colonies was observed on the surface of the culture solution, the wheat roots became rotted and the plants became atrophic or even died. Molecular biological analysis indicated that the bacterial community structure was significantly different in samples that were exposed to high levels of tetracycline (over 20 mg L^?1) than in samples that were exposed to lower concentrations. As the concentration of tetracycline increased, the diversity of the bacteria decreased. Additionally, several dominant sensitive species such as Sphingobacterium multivorum were suppressed by tetracycline, while some resistant species such as Acinetobacter sp. appeared or were conserved. The bacteria population tended to stabilize when the drug concentration exceeded 40 mg L^?1.     

Biodegradation of Chlorimuron-ethyl by the Bacterium Klebsiella jilinsis 2N3

Enrichment culturing of sludge taken from an industrial wastewater treatment pond led to the identification of a bacterium (Klebsiella jilinsis H. Zhang) that degrades chlorimuron-ethyl with high efficiency. Klebsiella jilinsis strain 2N3 grows with chlorimuron-ethyl as the sole nitrogen source at the optimal temperature range of 30–35°C and pH values between 6.0–7.0. In liquid medium, the degradation activity was further induced by chlorimuron-ethyl. Degradation rates followed the pesticide degradation kinetic equation at concentrations between 20 and 200 mg L^?1. Using initial concentrations of 20 and 100 mg L^?1, the degradation rates of chlorimuron-ethyl were 83.5 % and 92.5 % in 12 hours, respectively. At an initial concentration higher than 200 mg L^?1, the degradation rate decreased slightly as the concentration increased. The 2N3 strain also degraded the sulfonylurea herbicides ethametsulfuron, metsulfuron-methyl, nicosulfuron, rimsulfuron, and tribenuron-methyl. This study provides scientific evidence and support for the application of K. jilinsis in bioremediation to reduce environmental pollution.