Effects of cadmium on chlorophyll content, photochemical efficiency, and photosynthetic intensity of Canna indica Linn.

The effects of cadmium (Cd2+) on growth status, chlorophyll (Chl) content, photochemical efficiency, and photosynthetic intensity were studied on Canna indica Linn. Plant specimens that were produced from a constructed wetland and precultivated hydroponically in 20 L of 1/10 Hoagland solution under greenhouse conditions for I week were exposed to cadmium in concentrations of 0, 0.4, 0.8, 1.6 and 3.2 mg L- Cd2+, respectively. The results show that leaves were injured in the Cd2+ solution by the third day of exposure and the injury became more serious with an increase in the applied heavy metal. Under 3.2 mg L-1 Cd2+ treatment, growth retardation, the decrease of chlorophyll content from 0.70 to 0.43 mg g(-1) FW, and a decrease in Chl a/b ratio from 2.0 to 1.2 were observed. Chl a was more sensitive than Chl b to Cd2+ stress. The decrease was the same with photochemical efficiency. Photosynthetic intensity decreased by 13.3% from 1.5X10(4) mumol m(-2)s(-1) CO2 in control to 1.3x10(4) mumol m(2)s(-1) CO2 in the treatment of 3.2 mg L-1. Because Canna species are used in heavy metal phytoremediation, these results show that C. indica can tolerate 0.4 to 0.8 mg L-1 Cd2+. Therefore, it is a potential species for phytoremediation of cadmium with some limitations only at higher concentrations.

Processing network models of energy/environment systems

Processing networks are a variant of the standard linear programming network model which are especially useful for optimizing industrial energy/environment systems. Modelling advantages include an intuitive diagrammatic representation and the ability to incorporate all forms of energy and pollutants in a single integrated linear network model. Added advantages include increased speed of solution and algorithms supporting formulation. The paper explores their use in modelling the energy and pollution control systems in large industrial plants. The pollution control options in an ethylene production plant are analyzed as an example. PROFLOW, a computer tool for the formulation, analysis, and solution of processing network models, is introduced.

苔藓植物对沈阳市大气质量的指示作用

借助苔藓植物,应用大气净度指数(index of atmospheric purity)法与重金属(Mn、Fe、Cu、Cr和Pb)含量化学分析法相结合指示沈阳市的大气质量状况。结果表明:沈阳市样点可根据大气污染状况划分为3个区域,其中市区污染程度大于郊区,市区西部污染大于东部,南部大于北部;各区以Pb污染程度最为严重,值得重视。该结果与监测站所得空气污染指数(air pollution index)结果相符。

The past, present and future of phycology in China

Algae have been part of Chinese life for thousands of years. They are widely used as food and have been cited in Chinese literature as early as 2500 years ago. However, formal taxonomic studies on Chinese algae were initiated by foreign scientists only about 200 years ago, and by Chinese phycologists only about 90 years ago. This paper summarizes the history of modern phycological studies on Chinese algae and provides an overview of the achievements of phycological studies by Chinese scientists, especially on algal taxonomy, morphology, genetics, ecology and environmental research, physiology, biotechnology, algal culture, applied phycology and space phycology, in the last century. Recent development in phycological research focuses on algal floristic and molecular systematics, algal molecular biotechnology, applied phycology including micro and macroalgal cultivation and algal product development, and the roles of algae in environmental pollution control. These areas will also be the main focuses of Chinese phycological research in the foreseeable future.

企业效率表现和中国环境政策-以造纸企业为例

Understanding relationship between environmental protection and economic development is crucial to form practical environmental policy. At micro level, implementation of environmental regulations often causes production mills adjustment of technology which might leads to change of productive efficiency and cost, which, in turn, determine effort level of mills and even local government in pollution control. Using a stochastic frontier production model and a set of survey data on 126 paper mills from six provinces of China, we measure the technical efficiency changes and analyze the determinants of efficiency. in particular, we examine impact of environmental policy on paper mills' efficiency, using an indicator of environmental policy-the levy ratio of COD. We also estimate a simultaneous-equation model in which the levy rate and emission are jointly determined. The results indicate that there have been efficiency improvements during 1999-2003, when enforcement of environmental regulations have been tightened. The impacts, nevertheless, are different for different types of mills. We also find the levy ratio, which is influenced by both the local social and economic conditions and the characters of paper mills, such as scale, has strong impact on the abatement of the pollutant-COD. Additionally, paper mills' technical efficiency has positive effect on the reduction of the emission intensity of the pollutant-COD. These results lead a set of implications pertinent to policy improvement.

员工的组织支持感和工作压力对工作结果变量的作用——中国民航管制员研究

Both perceived organizational support and job stresses have impact on employees’ work outcomes. Great progresses have been made in past researches. However, there are many disputes about the impact of perceived organizational support (POS) on job performance (especially, safety performance), the impact of job stresses on job performance (especially, safety performance) and job attitudes, as well as the interaction of subordinates’ POS and job stresses, and the impact of supervisor on subordinates’ POS et al.. Thus, the aim of the study is to explore the impact of supervisors’ POS, leader-member exchange(LMX) on subordinates’ POS, the direct impact of subordinates’ POS and job stressors from task and rewards on work attitudes(job satisfaction, turnover intention) and safety behaviors(safety compliance and safety participation), and the interaction of subordinates’ POS and job stresses. Analyses are based on the data from interviewing of 20 staff, posts of a Chinese civil aviation Bulletin Board System (BBS) and surveys of 216 subordinates and 42 supervisors from two Chinese civil aviation Air traffic control centers (ATC). The major findings are listed as follows: Firstly, the exchange relationship between supervisors and members has impact on subordinates’ POS by the fully mediating role of subordinates’ perceived supervisor support (PSS). But supervisors’ POS have no impact on subordinates’ POS. Secondly, subordinates’ POS has a direct and positive impact on their job satisfaction and safety behaviors, and a negative impact on turnover intention. Specifically, the higher the employees’ perceived organizational support, the higher job satisfaction and safety behaviors, as well as the lower turnover intention they have. Moreover, POS has stronger relationship with safety participation behaviors than that of safety compliance behaviors. Thirdly, task-related stressor has no significant impact on job satisfaction, turnover intention and safety behaviors. And compensation-related stressor has significant and positive impact on turnover intention and safety behaviors, which means that with the compensation-related stress increases, turnover intention increases, safety behaviors including safety compliance and safety participation also increases. Fourthly, POS and task-related stressor, POS and compensation-related stressor have significant interaction, respectively. Specifically, POS moderates the relationship between task-related stressor and job satisfaction, and between task-related stressor and turnover intention. Moreover, POS also moderates the relationship between compensation-related stressor and safety compliance behaviors.