Potential ammonia emission from flag leaves of paddy rice (Oryza sativa L. cv. Koshihikari)

The present study aimed to investigate the potential ammonia (NH₃) emission from flag leaves of paddy rice (Oryza sativa L. cv. Koshihikari). The study was conducted at a paddy field in central Japan that was designed as a free-air CO₂ enrichment (FACE) facility for paddy rice. A dynamic chamber method was used to measure the potential NH₃ emissions. The air concentrations of NH₃ at two heights (2 and 6 m from the ground surface) were measured using a filter-pack method, and the exchange fluxes of NH₃ of the whole paddy field were calculated using a gradient method. The flag leaves showed potential NH₃ emissions of 25-38 ng N cm⁻² h⁻¹ in the daytime from the heading to the maturity stages, and they showed potentials of approximately 22 ng N cm⁻² h⁻¹, even in the nighttime, at the heading and mid-ripening stages. The exchange fluxes of NH₃ of the whole paddy field in the daytime were net emissions of 0.9-3.9 g N ha⁻¹ h⁻¹ whereas the exchange fluxes of NH₃ in the nighttime were approximately zero.     

中国排污权交易制度的实现条件研究

排污权交易目前在中国非常受重视,但其中也存在一些问题,主要是企业和政府尚没有处理好经济发展和环境保护的关系,也存在着制度设置不合理的问题。今后应重视排污权交易中的内部和外部条件的建设。内部条件主要有排污总量的确定和排污许可证的发放,外部条件主要包括政府加强环境执法力度和提供有效的排污信息。     

铁锋区噪声污染现状浅析

铁锋区经济的迅速发展,推动了辖区的机械加工业、餐饮业、建筑业的迅猛发展,随之而来的噪声污染环境问题有上升的趋势。本文结合铁锋区的实际情况,对辖区噪声现状进行分析,然后提出了具体的解决办法。     

基于排污权交易制度的流域水质管理体系研究

计划经济体制下行政和命令式的流域管理模式缺乏相应的利益调节和经济激励,因此难以适应市场经济体制下对水质资源管理的新需求。排污权交易制度作为一种新的治理流域污染的市场手段比政府行政管制手段具有更大的优势,它将市场机制充分地运用于环境资源的配置,在总量控制的前提下,通过排污权的交易,实现低成本治理污染,保护水质。从排污权立法、许可的最初分配和排污交易等方面建立排污权交易制度模式,为流域水质管理提供有益的思路。     

农产品贸易中虚拟水流的驱动因素研究

经济发展中的虚拟水贸易实施受到多种要素的影响与制约。在回顾当前虚拟水研究进展的基础上,从自然、经济、社会、生态、技术和政策六个维度系统分析了以农产品为主要载体的虚拟水贸易实施的影响因素,进而收集32个典型的虚拟水贸易实施国家的横截面数据,利用多元逐步回归的方法,以虚拟水对外依赖程度为因变量,对部分影响因素进行了实证检验,并根据实证结果从资源优化配置与区域经济贡献的角度解释了国内学者研究得出的我国区际间农产品虚拟水的流动格局。研究表明:耕地资源及水资源的稀缺程度、区域经济发展水平、社会调适能力是虚拟水进口的正向驱动因素,而农业用水效率则是虚拟水进口的逆向驱动因素。     

构筑我国绿色贸易体系的对策研究

环境与贸易紧密联系相互影响。我国现行的贸易体系不仅使贸易不可持续．而且给资源环境带来了很大压力。要实现优化贸易增长和缓解资源环境压力的“双赢”目标,需要构筑绿色贸易体系。绿色贸易体系是指通过一定的环境管理政策手段来绿化或优化贸易结构、调控贸易总量、提高贸易的环境效率。最终能够减少并扭转我国贸易的资源环境逆差和促进绿色贸易发展的政策体系。绿色贸易体系的政策框架包括：从具体政策措施看．包括加征产品出口的资源环境关税、制定基于环保目的的市场准入与准出制度,设计投资的资源环境导向等环保“阀门”和手段;从政策的作用点看．包括从产品、企业、行业三个层面着手;从政策的管理看,依据环境影响的程度。对产品、企业和行业分别进行鼓励、许可、限制和禁止贸易的分类管理。     

Trading rules and the environment: Does equal treatment lead to a cleaner world?

In this paper, we consider a three-stage game in the context of a competing exporters model to compare and contrast the effects of discriminatory and uniform (Most Favored Nation, MFN) tariffs on countries’ choice over environmental standards for varying degrees of pollution spillovers. Because of the presence of punishment effects and stronger own and cross-tariff effects, we find that discrimination yields higher standards than MFN (and free trade) independently of the extent of pollution spillovers. When pollution is local and incentives to free ride on other countries’ abatement efforts are weak, we show, however, that welfare is larger under MFN than under discrimination. In a dynamic setting, we consider the impact of symmetric and asymmetric treatments on the sustainability of an international environmental agreement (IEA) and obtain that multilateral cooperation is easier to sustain under discrimination than under MFN (or free trade).     

National water footprint in an input–output framework—A case study of China 2002

Water footprint is an indicator showing the consumption impact on environment with water equivalent, which allows a detailed quantification of water use directly and indirectly in sectors for the domestic and abroad final consumption. This paper presents a framework of calculating national water footprint (NWF) with input–output method on China 2002. The results indicated that the NWF of China was 381 m³/cap yr in 2002. A new indicator termed as national water footprint intensity (NWFI) is also derived from NWF to evaluate the water consumption intensities of different sectors. Then the evaluation of virtual water trade in sectors is followed, the results of which give a detailed quantification of net virtual water import of sectors, verifying that China is a net virtual water exporter concerning the whole national sectors, which is different from the previous studies. Finally, it is suggested that the sectors with high NWFI and volume of net virtual water export should be regarded as the priority of Chinese water-saving strategy.     

Turbulent velocity profile in fully-developed open channel flows

The determination of velocity profile in turbulent narrow open channels is a difficult task due to the significant effects of the anisotropic turbulence that involve the Prandtl’s second type of secondary flow occurring in the cross section. With these currents the maximum velocity appears below the free surface that is called dip phenomenon. The well-known logarithmic law describes the velocity distribution in the inner region of the turbulent boundary layer but it is not adapted to define the velocity profile in the outer region of narrow channels. This paper relies on an analysis of the Navier–Stokes equations and yields a new formulation of the vertical velocity profile in the center region of steady, fully developed turbulent flows in open channels. This formulation is able to predict time averaged primary velocity in the outer region of the turbulent boundary layer for both narrow and wide open channels. The proposed law is based on the knowledge of the aspect ratio and involves a parameter C_Ar depending on the position of the maximum velocity (ξ_dip). ξ_dip may be derived, either from measurements or from an empirical equation given in this paper. A wide range of longitudinal velocity profile data for narrow open channels has been used for validating the model. The agreement between the measured and the computed velocities is rather good, despite the simplification used.     

人民币汇率变动对我国进出口贸易的影响研究

随着我国加入WTO和对外开放水平的提高,人民币汇率变动对我国甚至世界贸易都会产生重大影响,因而越来越多地受到各方面的关注.笔者结合当前人民币汇率制度改革的发展历程,分析测定人民币汇率变动对我国贸易的影响并提出了政策建议.表2,参10.