新疆棉农对农业面源污染防治的态度和支付意愿研究

农业面源污染问题已经成为我国面临的最严重的环境污染问题之一,农户对农业面源污染防治的态度和支付意愿研究,对于政府制定相关政策措施意义重大。分别采用李克特五点量表、条件价值评估法、多元有序Logistic模型回归等方法对(1)棉农对农业面源污染防治的态度,(2)棉农对农业面源污染防治的支付意愿(WTP),(3)影响棉农支付意愿的社会经济因素进行研究。结果表明:新疆棉农对农业面源污染防治的态度非常积极,但是当与自身利益相冲突时,则趋向于以牺牲环境为代价;新疆每户棉农对农业面源污染防治的支付意愿是113.96元/年,49.64%的被调查者选择的支付区间是[12,60)元/年,累计百分比占70.65%;农户的教育水平和是否参加过农业专业合作组织是新疆农户农业面源污染防治支付意愿的主要影响因素。基于此,得出结论并提出相应的对策建议。     

我国畜禽养殖污染分区治理研究

随着我国畜禽养殖业的迅猛发展,畜禽养殖污染已经成为我国重要的污染源,威胁着我国的水环境和土壤环境等。文章利用我国各省畜禽养殖污染统计年鉴数据,依据各区的畜禽养殖污染总量压力、土地负荷压力和地表水负荷压力以及经济负荷压力等级对我国主要畜禽养殖污染区域特征进行了分析。结果表明,黄淮海地区为H-H-H-H型畜禽养殖污染区,是我国畜禽养殖污染压力最大的地区;青藏高原区为L-L-L-L型畜禽养殖污染区,是我国畜禽养殖污染压力最小的地区;东北区和东南区畜禽养殖污染压力也较大,分别为H-M-M-H型畜禽养殖污染区和H-H-L-M型畜禽养殖污染区;蒙新高原区和黄土高原区畜禽养殖污染压力中等,分别为H-M-M-H型畜禽养殖污染区和H-H-L-M型畜禽养殖污染区;西南山地区畜禽养殖污染压力中等偏低,为M-M-L-L型畜禽养殖污染区。基于上述研究,该文对各区畜禽养殖污染的分区环境治理提出了若干针对性建议。     

Economies of traffic density and scale in the integrated air cargo industry: The cost structures of FedEx Express and UPS Airlines

This paper examines the cost structures of the leading integrated air cargo carriers, FedEx Express and UPS Airlines. A total cost model is estimated for the two carriers using quarterly data on domestic operations and costs over a nine-year period (2003–2011). The estimated model indicates that the integrated industry exhibits increasing returns to traffic density and constant returns to scale. Accounting for carrier-specific differences in cost structure and network size, FedEx Express is found to be more cost-efficient than UPS Airlines. Looking at the carriers individually, UPS Airlines exhibits substantial economies of traffic density and constant returns to scale while FedEx Express' cost structure is characterized by weak economies of density and constant returns to scale. The combined effect of returns to density and returns to scale on the cost structures of integrated carriers is captured by economies of size. Both FedEx Express and UPS Airlines exhibit economies of size, indicating that carriers in the integrated industry can be more cost efficient by making appropriate adjustments to their network size as their output grows. Moreover, the relative cost-efficiencies of the carriers are reversed when their network-size differences are not controlled.     

Warehouse location problems for air freight forwarders: a challenge created by the airport relocation

The move of Hong Kong International Airport from the city centre to a suburban area in July 1998 provided sufficient capacity to meet the increasing demand of passenger and air-cargo flows in Hong Kong in the foreseeable future. However, the move has adverse side effects such as causing the readjustment of many existing systems and creating many imminent strategic problems. One of such problems is the warehouse location of freight forwarders: they have to decide whether they should locate their warehouses in the new airport, in current locations, or in new locations somewhere in the city. This paper delineates the results of a survey conducted in the summer of 1997 before the airport was relocated. The survey asked what decisions the freight forwarders had made and how they evaluated some potential warehouse locations. The paper also considers two mathematical models, which explain and predict, respectively, the location pattern of freight forwarder warehouses before and after the relocation of the airport.     

地下水污染防治区划研究

地下水在我国水资源体系中占有重要地位,可以直接对我国民众日常生产生活造成影响,在我国社会发展过程中,水资源污染问题日益严重,地下水污染问题成为了社会热门话题之一。基于此,从业人员应加大研究力度,不断对传统治理办法进行创新,以解决地下水污染问题。通过实际工作证明,在现有地下水污染治理策略中,防治区划手段治理效果最好,可以对地下水污染问题进行有效控制,避免地下水污染进一步扩大。     

珠三角区域跨界环境问题的经济分析

由于忽视了环境外部性的存在,目前珠江三角洲地区的跨界污染问题很严重;通过空间计量经济模型实证,发现某地区的污染排放量不止和本地区的经济增长有关系,也受邻近城市经济发展水平的影响,珠三角的环境质量与经济增长在空间上表现出相互作用;最后给出了解决跨界环境问题的对策建议。     

浅析我国环境污染责任保险面临的问题与对策

环境污染责任保险在我国推广的过程中取得了一定的成就,但同时也暴露出一些问题。本文在对存在的问题进行分析的基础上,提出了完善我国环境污染责任保险的对策,以期对我国环境污染责任保险的推广有所裨益。     

改良剂修复重金属污染土壤及环境风险评价

采用改良剂修复技术治理重金属污染土壤是一种有效的技术,土壤改良后的风险评估是一项重要内容。综述了改良剂修复重金属污染土壤后的环境风险评估方法和分析方法,并对今后的研究进行了展望。     

生活垃圾焚烧炉渣湿法与干法处理工艺比较

通过对生活垃圾焚烧炉渣的湿法和干法处理的工艺路线、金属提取程度、环境影响和经济指标等方面的对比分析,得出湿法工艺的金属回收率及整体收益较高,但存在较为严重的污水与沉淀污泥污染问题,如需妥善解决,将大幅度提升炉渣的处理成本。目前国内干法工艺的收益低于湿法,却有效的避免了对环境的二次污染,成为炉渣处理的主要发展趋势。     

The impact of Air Service Agreement liberalisation: The case of Nigeria

The positive impact of air transport liberalisation as suggested by economic theories and empirical studies has inspired many developing countries like Nigeria to liberalise some of its Air Service Agreements (ASAs). This paper seeks to examine the extent to which international air service liberalisation has impacted upon Nigeria ten years after it was introduced. The research developed a cross-sectional model with passenger traffic as the dependent variable, while macroeconomic factors (trade and GDP), historical links, distance and ASAs (a proxy for liberalisation) served as independent or predictor variables. The analysis revealed a set of ASA stages in the country's policy-making process (restricted Bilateral Air Service Agreement, Open Skies Agreement and Yamoussoukro Declaration). Further analysis showed that the predictor variables were all significant in explaining passenger demand. The model demonstrated that the liberalisation of market access to the Open Skies Agreement level could stimulate traffic growth by at least 65 percent. The findings can assist in guiding policy and industry stakeholders in future decisions relating to liberalisation and ASAs.