Productive efficiency, environmental efficiency and their determinants in farrow-to-finish pig farming in Taiwan

Two sub-technologies, pig production and wastewater control, in pig farm operation are considered. This paper develops a multi-activity DEA (data envelopment analysis) model to simultaneously measure productive efficiency (PE) and environmental efficiency (EE) in farrow-to-finish pig production in Taiwan, and to explore several theorized causal relationships between performance and farm-specific knowledge. The empirical results prove that the estimated PE and EE do not belong to the same distribution. That suggests that using an identical ‘technical efficiency’ index to represent PE and EE would get a biased result when undesirable outputs are considered. PE is higher than EE, but the two are positively correlated. Analytical results support the presence of economies of scale in sample farms. Providing training to farmers and computerizing farm operations are critical determinants of PE; providing training to operators of wastewater control facilities and the operator's education level showed a positive impact on EE. Such information is valuable for both farmers and the authorities in making decisions to enhance productivity and environmental protection in the pig sector in Taiwan.     

环境激素阿特拉津对家蚕卵巢培养细胞(BmN)凋亡的影响

为探讨利用鳞翅目昆虫对环境激素进行生物学评价和监测的方法,用2,3-二苯基溴化四唑(MTT)、4’,6二乙酰基-2-苯基吲哚(DAPI)荧光染色和单细胞凝胶电泳(SCGE)、流色细胞仪检测(FCM)等技术,分析检测了环境激素阿特拉津(AT)对体外培养家蚕卵巢细胞(BmN)细胞增殖和凋亡的影响。结果显示：AT浓度超过0．0625mmol/L,显著抑制了BmN培养细胞48h的存活率(p＜0．001),LC_(50)为0．0703mmol/L;0．0625～0．5000mmol/L AT处理24h后,BmN细胞核出现明显的凋亡现象;0．5000mmol/L的AT处理48h后,BmN细胞DNA链发生断裂。AT对BmN细胞增殖和凋亡的影响有明显的时间-剂量效应。长期处于AT污染的环境中对鳞翅目昆虫可能有严重的细胞毒性。     

State-centered versus Nonstate-driven Organic Food Standardization: A Comparison of the US and Sweden

Organic food standardization is an increasingly important strategy for dealing with consumer concerns about the environment, animal welfare, health, and the economic structure of food production. But the ways in which this consumer-oriented strategy is introduced, organized, and debated vary considerably across countries. In Sweden, a nongovernmental organization [KRAV (Association for Control of Organic Production)] – consisting of social movement organizations, associations for conventional and organic farmers, and the food industry – has been quite successful in promoting organic food labeling as an eco-label. KRAV has developed a complementary position vis-à-vis the state and EU regulatory framework. In the US, the federal government controls standardization. The government frames the label as a “marketing label,” thus rejecting the idea that organic food production would have any significant advantages for the environment or, indirectly, for human health. This framing is separate from the ones created by organic constituencies, leading to deeper controversies than in Sweden. The purpose of this paper is to examine why standardization has followed different patterns in the two settings. We analyze context factors (i.e., political culture, pre-regulatory arrangements, and organizational structures) and process factors (i.e., framing and organizing). What are the benefits of a state-centric versus a nonstate-driven approach regarding powerful standardization? The paper shows that both settings provide not only “threats of regulatory occupation” from actors not committed to organic principles but also avenues for substantial standardization in the future, albeit through different channels.     

云南鹤庆桑树光合生理特性日变化研究

通过对云南鹤庆地区栽植的农桑12号的净光合速率、蒸腾速率等光合特征参数及其相应环境因子的日变化测定,探讨了云南红土高原桑树的光合生理特性.结果表明,桑树净光合速率日变化曲线呈“双峰”型,有明显的“午休”现象,且光合“午休”现象主要受非气孔限制因素的影响.蒸腾速率与气孔导度的日变化呈“双峰”型曲线,并且呈极显著的正相关关系;胞间CO2浓度的变化趋势与净光合速率的变化相反.各环境因子对桑树光合特征参数的影响较大,光合有效辐射对净光合速率的影响起决定性作用.     

生态服务价值法在土地利用总体规划环境影响评价中的应用——以河南周口为例

该文分析了生态服务价值法在土地利用总体规划环境影响评价中应用的必要性,并结合周口市新一轮土地利用总体规划修编的实例进行了分析研究,结果表明,生态服务价值评估方法可以将土地利用规划目标及规划方案的生态效益量化为简单易懂的货币形式,为土地利用总体规划环境影响评价提供了一种可以量化的方法。     

农业生态经济系统能值分析指标的商榷

应用能值分析方法对农业生态经济系统的能值投入及产出结构进行了研究,通过计算建立了能值指标体系,并与不同地区进行了对比,得出环境负载率和能值投资率2个重要的能值指标在计算和对比中还存在较大差别,需要进一步深入研究。     

环境胁迫因子对鱼类氧化压力的影响

活性氧(ROS)是鱼类生活中不可或缺的成分,一般情况下ROS的产生与分解都处于稳定的动态平衡中。这种平衡一旦被打破,ROS含量上升,细胞组分发生改变,机体将产生氧化压力。综述了鱼类对ROS的应对方式,并对氧化压力进行了定性分析。环境胁迫因子(如温度、氧含量、盐浓度、过渡金属离子和农药等)能通过改变ROS的产生和分解的平衡来改变自然条件和人工条件下的氧化压力。该领域未来发展的方向将对氧化压力进行更精确地描述,包括其主要特性和作用机理。研究鱼类氧化压力对发育学、衰老学、病理学能起到一定的作用。     

环境工程综合性实验系统建立对优化专业实验教学的思考

分析了随着环境工程专业的快速发展和不断完善,传统的实验教学逐渐暴露出的很多新问题,指出实验课程设置少,重复性多,关联性差,无系统性,实验设备缺少等问题急需要解决。为了提高学生实验的主动性、创造性和综合运用知识的能力,提出了环境工程综合性实验系统,并从其组成、运行及考核等多方面介绍了该系统的优越性。     

气候变化对黄河首曲生态退化的影响

玛曲湿地被称为黄河的"蓄水池"和"高原水塔"。然而近30年来,由于气候变化和人类的过渡利用等原因造成了玛曲湿地的黄河"蓄水池"功能萎缩,,对当地生态环境和居民的生产和生存造成了严重的威胁。     

Effect of the landscape context on the density and persistence of a predator population in a protected area subject to environmental variability

Protected areas are the most important tool for the conservation of biodiversity. However, many species are area-demanding and their populations seldom meet their space requirements in reserves. In this context, the unprotected exterior becomes an important part of their home range, and variations in habitat quality of the surroundings of a protected area might affect the dynamics of populations. Using a spatially explicit simulation model, we studied the effect of the surrounding landscape of a protected area on the density and persistence of a predator population inhabiting inside the reserve in different conditions of environmental variability. We simulated individuals of a predator population, their herbivorous prey and a vegetative substrate in a landscape comprised of a square protected area and different types of habitat quality outside the reserve. We studied the combination of three substrate qualities of protected area (inside) with three of the landscape context and three levels of variability of productivity. Our results showed that there were strong effects of both the relative quality of the surrounding landscape and of the environmental variability on the density and persistence of the simulated population inside the protected area. More importantly, we showed that complex patterns emerge when spatial heterogeneity and temporal variability interact with population dynamics. Specifically, under high environmental variability, when the protected area had a high habitat quality, the highest population persistence was not attained when the exterior was also of high quality, but when the surroundings had an intermediate quality. The latter result suggests that, under the mentioned conditions, small enhancements in the quality of the matrix may have, for some species, better effects on increasing persistence in small reserves than large and costly enhancements.