Prevention versus Treatment under Precautionary Regulation: A Case Study of Groundwater Contamination under Uncertainty

Policy discussions on agricultural pollution problems characterize prevention as more cost effective and precautionary than ex post treatment. We derive conditions under which treatment alone is more cost effective in situations involving multiple sources of emissions, multiple sites affected, and a commonly used precautionary approach to uncertainty. We also show that a greater degree of precaution can result in less reliance on prevention. An empirical case study indicates that treatment alone is the most cost-effective means of dealing with nitrate in most Maryland community water system wells. The use of leaching prevention measures is restricted to the most intensive poultry producing areas. The incremental cost of precaution is substantial.     

Stochastic Technology, Risk Preferences, and Adoption of Site-Specific Technologies

A model of farmer decision making is developed to determine the extent to which uncertainties about soil fertility and weather affect the value of site-specific technologies (SSTs) using jointly estimated risk and technology parameters. Uncertainty can lead risk-averse farmers to apply more fertilizers and generate more pollution than in the certainty case. Ignoring uncertainty and risk aversion would overestimate the economic and environmental benefits of SSTs and underestimate the subsidy required to induce adoption. Accounting for uncertainties and risk preferences might explain the low observed adoption rates of SSTs. Improving the accuracy of SSTs would increase the incentives for adoption.     

小氮肥清洁生产实践

文章介绍了沅江市氮肥厂废水闭路循环、尾气回收、废渣综合利用等工程,并介绍了该厂的生产工艺、污染源分布及排污特点。     

纯氧曝气的研究进展

介绍了纯氧曝气的生化机理、应用领域、供氧方式、污泥性能等以及它与普通空气曝气相比在技术、经济方面显示出的优越性。随着纯氧曝气的发展和国家新标准增加了脱氮除磷方面的排放要求，使得纯氧曝气在城市污水处理老厂的改造和新厂的建设中具有很好的前昔。     

Cost Uncertainty and Unilateral Abatement

Unilateral abatement is sometimes advocated in order to set a good example that will make other countries follow. The aim of this paper is to investigate whether existence of correlated cost uncertainty provides an incentive for a country to undertake unilateral abatement. The theoretical model is driven by two main mechanisms; first, a learning effect, as the follower country might reduce its risk premium as it can observe the cost level in the leader country. Second, there is the public good effect, i.e., the marginal benefit of abatement declines when abatement is a public good and other countries contribute to pollution reductions. Results shows that unilateral abatement would be efficient in reducing uncertainty about the unit costs of abatement if a country with low cost uncertainty would undertake abatement first, while a country with initially high cost uncertainty would follow. However, countries may prefer to act simultaneously because of the larger uncertainties that are inherent in a sequential game.      

300MW循环流化床锅炉NO_x控制分析

本文从300MW循环流化床锅炉燃烧控制和烟气排放现状出发,对300MW循环流化床锅炉NOx排放超标的原因、现状进行深入分析,探讨了控制NOx达标排放的措施,从而为300MW循环流化床锅炉的安全运行、环保达标排放控制提供参考和积累经验。     

浅圆仓环流降氧工艺研究

本文主要对环流充氮工艺进行研究,结果表明：以氮气95%和98%两种浓度比以90%、95%和98%三种浓度进行阶段环流充氮可以节能40%左右;氮气浓度95%保持35天能够抑制锯谷盗、赤拟谷盗和书虱等的生长发育甚至死亡;在密闭保持期间氮气在粮堆中以相似的速度进行自由扩散,而且当仓内氮气浓度大于95%后继续进行补氮成本将大幅增加。     

地下水中硝酸盐污染及修复技术

文章介绍了地下水中硝酸盐污染来源,并阐述了地下水中硝酸盐污染的三种修复技术,即物理化学修复技术、化学修复技术和生物修复技术,同时还回顾了利用这些修复技术治理硝酸盐引发的地下水污染方面的研究成果,最后提出了防治地下水中硝酸盐污染的建议。     

碳源对氮素在不同潜流带介质中的迁移转化规律研究

通过室内土柱实验模拟氮素在不同沉积物的潜流带中迁移转化途径,选取粗砂、细砂、粉砂三种介质,以浓度为65.5mg/L的硝酸钾溶液为原水,研究硝态氮在不同沉积物的潜流带中的环境行为;再通过补充碳源,研究碳源对氮的迁移转化过程的影响。实验结果表明,在不同的沉积物介质中,氮的迁移转化不同,主要受介质孔隙度和介质中有机质的制约。由于粉砂介质中孔隙度较小,有利于微生物的附着,且有机质含量较多,反硝化作用和异化还原作用强烈,所以硝酸盐氮下降的最多,而在粗砂介质中孔隙度相对较大,不利于微生物附着,且有机质含量相对较低,反硝化作用和异化还原作用较弱,硝酸盐氮下降的较少。而添加碳源后,反硝化作用和异化还原作用增强,三根柱子中的硝酸盐氮都降到很低的值,说明碳源对潜流带中硝态氮的去除起着重要的作用。     

Reduction in nitrogen fertilizer use results in increased rice yields and improved environmental protection

Overuse of nitrogen fertilizer represents a considerable environmental problem globally, but especially in China. Recently, a recent approach on an experimental scale based on the diffusion of the so-called Three-Control Technology (TCT) successfully alleviated the overuse of nitrogen fertilizer in southern China villages in the Guangdong Province, serving as a reference point for other rice-producing countries tackling similar challenges. Here, we assessed the correlation between rice yields and reduction in the use of nitrogen fertilizer following the introduction of TCT. Our study was based on the collection of primary data from 248 households randomly selected from four rice-growing areas of Guangdong Province, China. Our results show that TCT significantly improved the efficiency in the use of nitrogen. Crucially, participating farmers, including both full adopters and partial adopters, were found to fundamentally change their application practices of nitrogen fertilizer, resulting in major improvements in the local soil and water systems.