Estimating the benefits of recreation under conditions of congestion: Comments and extension

The purpose of this paper is to comment on and extend the analysis of a paper by Wetzel. He uses a commonly accepted model of demand for a congested recreational resource and shows how the Clawson method of estimating a recreational demand curve relates to it. Much of his analysis is useful but he errs in his interpretation of the proper value of consumer surplus. In this paper a specific formalization of the demand model is developed for the first time and it is used to show the correct measure of consumer surplus and how to specify the proper level of use for the congested resource.     

Estimating the benefits of recreation under conditions of congestion congestion

In a recent issue of J. Environ. Econ. Manag. Wetzel showed that the standard travel cost technique will understate recreation benefits under congested conditions because changes in entry fee lead to lowered congestion levels. This comment indicates that benefit projections derived from the travel cost procedure may theoretically overstate the true value of recreation if rising income levels shift the demand curve upwards but fail to account for the contrary effect of increased congestion. The magnitude and direction of the bias that results from omission of a congestion variable is, however, indeterminate when standard econometric techniques are used to develop benefit projections.     

Dust emission calculations in open storage piles protected by means of barriers, CFD and experimental tests

The importance of open mineral storage piles in bulk solids port terminals have increased considerably in recent years in Europe and USA (in Spain, great extensions of transoceanic ports are being made) to address the increasing demand of raw material importation due to local mining operation closure. These storage piles are affected by the climatologically processes and the dust emission to the atmosphere, causing repercussions to health and environmental, which is intimately related to the air velocity, according to USEPA studies, maximum ratio of dust emission emitted from CFD and software Ansys CFX 10.0 is determined. In addition, an emission variability study based on the pile distance of different height solid barriers is developed, reducing the emission to 66%. The studies have been contrasted by published investigations and industrial measurement.     

Trends in Natural Resource Economics in JEEM 1974–1997: Breakpoint and Nonparametric Analysis

The purpose of this paper is to identify trends in natural resource economics as reflected in publications in JEEM over the period since its inception in 1974. A secondary purpose is to suggest an explanation for any patterns we observe in the data. The data base consists of all articles published during this period, classified by topic and method. We apply statistical techniques of increasing sophistication to determine the existence of trends, and interpret the results by appealing to what we characterize as forces of demand and supply.     

Willingness to Pay for Quality Improvements: Should Revealed and Stated Preference Data Be Combined?

In this article we propose theoretically consistent welfare measurement of use and nonuse values for an improvement in environmental quality with revealed and stated preference data. An analytical model based on the comparative static analysis of the variation function that describes the relationship between recreation demand and dichotomous choice contingent valuation models is estimated. Our results show that revealed and stated data should not be combined under the same assumed preference structure unless the two decisions imply the same change in behavior induced by the quality change. In addition, our results indicate scope effects in willingness to pay measures estimated with stated preference data.     

Estimating net benefits of recreation under conditions of excess demand

The public provision of outdoor recreation necessitates the development of nonmarket measures of the value of resources in recreational use. Such values can be used as surrogates for market values in the decision-making process. Another aspect of recreation as a publicly provided good is the absence of a mechanism to eliminate automatically excess demand. The absence of such a mechanism has resulted in conditions of excess demand at many recreation sites.This paper deduces the implications of excess demand for the travel cost method of benefit estimation. We show that when excess demand results in rationing at a particular site, the travel cost method will underestimate the true benefits of the site. The results are important because they help identify the direction of bias of one measure of the benefits from the use of a natural resource.     

Schadstoffbelastete Erzeugnisse im Verbraucherbereich: Wird REACH zu Verbesserungen führen?

Aim and Background Currently, the protection from hazardous substances occurring in consumer articles is often insufficient. In this paper, we discuss whether this situation will improve relevantly in the course of the implementation of the new European regulation on chemical substances (REACH). Changes under REACH may be heterogeneous. Therefore, differential effects depending on the tonnage as placed on the market, on the amount of substances contained in an article, and depending on timelines and exemptions for meeting the legal requirements, are discussed in this paper, together with a presentation of some uses of substances serving as examples. Discussion and Conclusions If substances are adequately registered, all identified and supported uses including their use in articles should be assessed. Therefore, where the full implementation of the registration conditions applies a substantial improvement may be expected due to REACH. Usually, producers or importers of articles are not required to register substances contained in these articles. Instead, the manufacturer or importer of the respective substance is usually responsible for registration, if exposure to the substance cannot be excluded and emission of the substance from an article is not the intended purpose. This may differ for substances intentionally released from articles. Additional obligations for substances not intentionally released mainly apply to substances of very high concern (SVHC). For the latter, the producer or importer of articles has to notify the European Chemicals Agency (ECHA) on the occurrence of the respective SVHC in articles. This information is important, especially because substances in imported articles may not be registered in advance. Authorisation within REACH is a very far reaching and effective tool of the legislation. However, authorisation is not required for SVHC imported as components of articles. Therefore, one main effect intended by REACH, i.?e. the substitution of SVHC, may possibly be undermined by importers of SVHC in articles. Restrictions, as specified in Annex XVII of REACH, offer a powerful opportunity to improve health and environmental safety with respect to hazardous substances. We support an extended understanding of what is defined as a “substance of concern” in the context of restrictions. This definition should be broader than just what is currently covered by the term SVHC. Consequences of restrictions may equally apply to European producers and importers of articles from outside of Europe, which contain such substances of concern. Another instrument currently closely linked to SVHC (in its more restricted definition), is the obligation of the producer or importer of articles to provide information according to article 33 (REACH). The downstream recipient of an article has to be informed on the content of SVHC in this article and how its safe use is ensured. Warehouses, wholesalers and other traders may therefore be aware of the SVHC contained in articles and may look for substitutes without such ingredients. Also, consumers may request this information on SVHC (just provided on demand) and are thus enabled to decide to buy other articles with less hazardous properties.     

医学环境影响评价的规范研究

本文以医学环境影响评价的目的,内容,原则,范围及对象,评价程序,模式为主要内容,试图提出医学环境影响评价的规范,使医学环境影响评价更具有可操作性及科学性,从而对控制污染,管理环境,规划环境提供科学依据。     

Environmental aspects of biofuels in road transportation

Energy is a vital and growing need for human activities such as transport, agriculture and industry. The transport and agriculture sectors are major consumers of fossil fuel. However, availability of fossil fuels is limited. The use of fossil fuels is of increasing environmental concerns because it produces toxic airborne particulates and greenhouse gases such as CO₂. The increasing industrialization and motorization of the world led to a steep rise for the demand of petroleum-based fuels. Hence, it is necessary to seek alternative fuels, which can be produced from resources available locally within the country such as alcohol, biodiesel and vegetable oils. Biodiesel is defined as the mono alkyl esters of vegetable oils or animal fats. Biodiesel is the best candidate for diesel fuels in the diesel engines. The advantage of biodiesel over gasoline and petroleum/diesel is its eco-friendly nature. This article reviews the production, characterization and current status of biofuels mainly biodiesel along with the environmental impacts of particulate matter, greenhouse gas emissions originated from biodiesel.     

Thalassia testudinum productivity: A field comparison of measurement methods

A 6-day in situ comparison between the Wetzel inorganic ¹⁴C uptake and Zieman leaf-biomass techniques for measuring net primary production rates in the seagrass Thalassia testudinum was performed in the northeastern Gulf of Mexico. Measurement differences between the two methods were insignificant when the ¹⁴C uptake technique was corrected for sediment ¹⁴C uptake (13%), incubation-chamber light-energy absorption (14%) and differences in total light-energy which resulted from the experimental design (7.7%). These results reinforce previous observations that the ¹⁴C technique estimates net particulate-carbon production.     

Valuing nature in a general equilibrium

We explore the consequences of modeling the demand for environmental quality improvements as a fully integrated part of a general equilibrium demand system in an applied general equilibrium (or CGE) analysis. Demand for non-market goods depends on a full range of relative prices as well as environmental outcomes. We simulate the effects of reducing two air pollutants to improve human health and three ecosystem services provided to households. The ecosystem services make non-separable contributions to household utility. We find that willingness to pay measures of use-based ecosystem services are impacted by changes in demand for complementary market goods. Demand for these goods shifts due to pollution reductions that enhance ecosystem services. Partial equilibrium estimates of these use values can be measured with substantial error if they fail to account for the general equilibrium adjustments caused by pollution. Over 300 calibrations of the model identify the model features important to these errors. We find that effects on ecosystem services associated with non-use values have important implications for the feedback effects on use related measures of economic tradeoffs. This is due to how our model integrates market and non-market effects, reflecting the non-market services importance to general equilibrium market outcomes.     

网络音乐作品著作权的保护的几点建议

在数字作品著作权越来越频繁受到侵犯的今天,如何对其进行有效的保护,维护著作权人的利益,给法律提出了更高的要求.因此,来阐述与著作权保护相关的几个理论问题,提出对网络音乐作品保护的几点建议,以形成一个以保护音乐作品著作权人利益为宗旨的保护体制.     

Durable goods and long-run electricity demand: Evidence from air conditioner purchase behavior

I estimate a dynamic structural model of demand for air conditioners, the most energy-intensive home appliance in the US. The model explores the links between demand for durable goods and expected changes in key attributes: energy efficiency and price. I incorporate expectations explicitly as a feature of the choice setting, and use parameter estimates from the model to calculate durable good demand elasticities with respect to energy efficiency, electricity price, and price of the durable itself. These estimates fill a large gap in the literature, and also shed light on consumer behavior in this setting. Results indicate that consumers are forward-looking and value the stream of future savings derived from energy efficiency.     

Wet oxidation of debarking water: changes in lignin content and biodegradability

The purpose of the research was to estimate optimal conditions for wet oxidation (WO) of debarking water from the paper industry. The WO experiments were performed at various temperatures, partial oxygen pressures and pHs. The experiments showed that lignin degradation and organics removal are affected remarkably by temperature and pH. At different WO conditions (pH 12, T 130–200°C), 78–97% of lignin reduction was detected. pH value of 12 caused faster removal of tannins/lignin content; pH value of five was more effective for removal of total organics, represented by chemical oxygen demand (COD) and total organic carbon. The highest biodegradability [biological oxygen demand (BOD)/COD] of 0.72 was obtained at a pH of ten and temperature of 200°C.     

啤酒废水处理工程运行分析

桂林漓泉有限公司污水处理厂经过改造,采用UASB－SBR工艺处理啤酒废水,处理后出水水质达到GB 8978－96国家污水综合排放标准。文章主要对UASB装置的启动,运行以及控制因素进行了论述和探讨。     

Estimating the benefits of recreation under conditions of congestion

The public provisions of free or below cost outdoor recreation sites has resulted in the use of various methods to evaluate the demand. One method is to use travel cost as a price proxy. However, this mechanism does not take into account problems raised by congestion. This paper shows that the use of the travel cost method will always underestimate the true benefits provided by recreation at a site because of the role of congestion. The results are important because they identify a source of bias in measuring benefits of outdoor recreation and suggest how it may be corrected.     

On the Compatibility of a Conservation Ethic with Biological Science

Abstract:  If value entails or implies purpose, it follows that natural objects (e.g., endangered species) lack value and thus cannot be worth protecting except for a purpose they may serve—either the end for which God created the world (according to natural theology) or some use to which human beings may put them (according to a consequentialist or utilitarian ethic). If value requires purpose, the refutation of natural theology after Darwin implies that humanity has no obligation to respect or preserve the natural world except insofar as it is economically efficient to do so. Drawing on the distinction between explanation and communication found in Calvinist theology, I argue that value does not entail purpose. The expressive, aesthetic, or communicative aspects of nature may be valuable or endow natural objects with value apart from any use or purpose these objects may serve. The crucial distinction between explanation and communication—one scientific, the other aesthetic—offers a rationale for an obligation to protect the natural world that may appeal to members of faith communities and to biologists and other scientists. This approach also helps resolve the "lurking inconsistency" some scholars see in the relationship between a deterministic biological science and a conservationist ethic.     

微生物传感器快速测定BOD标准方法的技术说明

国家环保总局颁布了微生物传感器快速测定生化需氧量（BOD）的标准方法。文章主要就标准中起草过程、主要技术指标、适用范围、干扰物质、样品贮存等主要内容及实验结果加以说明。     

Temporal and spatial assessment of natural resource use in China using ecological footprint method

China has about 20% of the world's population. With rapid economic development and substantial population increase, China is now faced with severe conflicts between limited natural resources and increasing resource requirements. In this study, we used the ecological footprint method to assess the resource demand and supply conditions of each land use in China between 1978 and 2003. In order to provide insight into the spatial heterogeneity of resource demand and supply conditions, we also assessed the ecological footprint at provincial level in 2002. An ecological footprint curve method was introduced to compare differences in natural resource use, economic development and technological progress among different countries and provinces. The results showed that the ecological footprint, biocapacity and ecological deficit per capita for China have all been increasing during 1978–2003. The ecological footprints per person in northern and eastern China were larger than those in southern and western China. The ecological deficits per person in southern and eastern China were more severe than those in northern and western China. Though the resource use efficiency has increased considerably during 1978–2003, it was still much lower than those of the Netherlands, France, South Korea, Mexico, the Philippines and India.