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在物科平衡原理的基础上,应用一种新的理论-土壤颗粒内部屏理论,建立了定量描述土地生物处理有污染物过程的综合数学模型,数学模型为球体扩散模型,其中包括用线性吸附等温线表示的可逆吸附和解吸过程,用假一级反应动力学方程表示的不可逆土壤屏蔽反应过程,用Monod方程表示的生物解过程,数学模型采用有限差分法求解,用砂壤土进行实验,实验结果与模型计算结果基本拟合,表示模型基本可靠,利用数学模型,可以定量预测有机污染物在土壤系统中进行生物处理,以达到科学指导土地生物处理工程的目的。 相似文献
414.
对广西省桂林市1988-03-16-1988-03-29出现的四次系统酸性降水,进行了降水的连续联样和过滤,用电子显微镜观测降水中的不可溶成分,共得到了12种元素,即Ar,Mg,Al,Si,P,S,Cl,K,Ca,Fe,Ni和Cr。用平均值法和聚类法,分析了桂林酸雨中12种不可溶元素的重量谱特征,以及它们与降水系统之间的关系。 相似文献
415.
A grand challenge facing government, industry, and academia in the relationship of our technological society to the environment is reinventing the use of materials. To address this challenge, collaboration from an interdisciplinary group of stakeholders will be necessary. Traditionally, the approach to risk management of materials and chemicals has been through inerventions intended to reduce exposure to materials that are hazardous to health and the environment. In 1990, the Pollution Prevention Act encouraged a new tact-elimination of hazards at the source. An emerging approach to this grand challenge seeks to embed the diverse set of environmental perspectives and interests in the everyday practice of the people most responsible for using and creating new materials—chemists. The approach, which has come to be known as Green Chemistry, intends to eliminate intrinsic hazard itself, rather than focusing on reducing risk by minimizing exposure. This chapter addresses the representation of downstream environmental stakeholder interests in the upstream everyday practice that is reinventing chemistry and its material inputs, products, and waste as described in the “12 Principles of Green Chemistry”. 相似文献
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IntroductionThe objective of this research is to investigate the effects of monthly weather conditions on traffic crash experience on freeways, considering the interactions between weather, traffic volumes, and roadway conditions. Methods: Data from the state of Connecticut from 2011to 2015 were used. Random parameters negative binomial models with first-order, autoregressive covariance were estimated for representative types of freeway crashes (front-to-rear, sideswipe-same-direction, and fixed-object), most severe crashes (i.e., fatal and injury crashes), and non-injury crashes (i.e., property-damage-only crashes). Results: Major findings are that variations in monthly traffic volumes, roadway geometry, and weather conditions explain much of the variations in monthly traffic crashes. Time effects exist in the panel monthly data for all types of crashes. Taking into account this effect improves model prediction results. When the raw weather measures are highly correlated, using dimension reduction techniques helps to extract more interpretable weather factors. By considering the interaction effects between roadway condition variables, additional findings were found. In general, lower temperature, more heavy fog days, decreased precipitation, lower wind speed, higher monthly traffic volumes, and narrower inside shoulder were found to be associated with higher monthly crashes. The effects of area type and outside shoulder width change dramatically as the number of through lanes changes. Practical applications: The findings of this research could help researchers and general readers gain a better understanding of the effects of monthly weather conditions and other roadway factors on freeway crashes and give engineers practical guidelines on improving freeway safety. 相似文献
417.
裂解温度对新疆棉秆生物炭物理化学性质的影响 总被引:1,自引:0,他引:1
生物质的裂解温度影响其所生产的生物炭炭的物理和化学性质,进而影响其田间应用效果。棉花秸秆是干旱区特别是新疆地区的主要农业生物质资源,其生物炭利用途径有望克服现有秸秆利用途径的不足,但对棉秆生物炭理化性质及其变化的认识还很缺乏。本文在不同的裂解温度下对新疆棉秆生物炭物理和化学性质进行研究,发现随着裂解温度的升高,生物炭的产率、阳离子交换量、O/C和H/C值降低,p H、电导和持水性能提高,Na+、K+趋势不明显,Cl-和SO2-4等盐碱化离子以及Ca~(2+)、Mg~(2+)营养元素含量随温度的升高降低;C、N、S、C/N和灰分等均提高,NH+4-N在550℃碳化条件下含量最高。因此在田间应用中,应针对土壤特点和解决的问题,调控碳化温度,从而达到趋利避害的目的。 相似文献
418.
Multiple mating is likely to be costly for ant queens and yet it is common. Whether multiple mating brings benefits to queens
that outweigh the costs has, therefore, received considerable theoretical attention. Empirical tests of hypotheses have been
scarce and no clear evidence has been reported. We tested the “multiple-mating-for-more-sperm” hypothesis on individual young
queens in a natural population of the leafcutter ant Atta colombica, a monogynous ant characterised by very large colonies and high colony longevity. We found that the number of sperm stored
by queens was positively correlated with the number of mates per queen estimated through mother-offspring analysis with microsatellite
DNA markers. Queen sperm stores increased on average by 30 million sperm for each additional mate. Life-history information
for Atta indicate that the number of stored sperm observed is likely to constrain the reproductive lifespan of queens in nature. Multiple
mating, despite costs, may therefore enhance the fitness of Atta queens because it enables them to store more sperm.
Received: 19 September 1997 / Accepted after revision: 7 December 1997 相似文献
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