酸性矿井水沉淀污泥中锰及其他金属的化学稳定性

(美国)联邦法规1985年a和b对矿井水排放标准做了具体的规定,见表1。为满足排放要求,必须依法对酸性矿井水进行处理。这主要涉及到以下三大步骤:(一)向酸性矿井水加碱性物质,通常有CaO、Ca(OH)_2或NaOH;(二)自然曝气或机械曝气;(三)沉淀。当酸性矿井水PH值调到7或8时,且有足够的沉淀时间,绝大多数矿井水     

First observation of different diffusion coefficients for two conformers in a neat liquid

 Self-diffusion coefficients were studied for the highly polar liquid N-methylformamide at pressures up to 200 MPa between the melting pressure curves and 420 K by the spin-echo method. N-Methylformamide exists as a mixture of two conformers in the neat liquid. These conformers have large differences at lower temperatures in their dynamic and structural properties. The self-diffusion coefficient of the cis-conformer being 17% lower than that of the trans-conformer at the same T and p. This is the first observation of such an effect. The experimental study is supported by Monte Carlo (MC) calculations which show that the first neighbors around a cis conformer are arranged differently than in an all trans liquid. The difference leads in the simulations to a much lower dielectric constant for the trans-cis mixture and might also explain the retardation of diffusion for the cis conformer. Received: 15 November 1999 / Accepted in revised form: 28 February 2000     

白洋淀地区的多氯联苯污染研究

对白洋淀地区不同类型纸厂排水口底泥及保定市排污渠底泥进行了ＧＣ／ＥＣＤ分析，可萃取有机氯（ＥＯＣｌ）含量测定，检出了多氯联苯和有机氯农药。用截止分子量为１０００道尔顿的透析袋方法对相应地区的水体进行了检测，发现水体中可检出含氯农药六六六，但多氯联苯等由于水中存在浓度低未能检出，同样样品的ＧＣ／ＭＳ／ＣＯＭ结果表明，水体中主要存在的亲脂性有机污染物为：蒽酮、蒽二酮、苯胺、氯代烃、邻苯二甲酸酯类和苯系物。     

Competition of the active roots of Cassia siamea Lam. and Zea mays L.(cv.Katumani Composite B) in an alley cropping trial in semi arid Kenya

A study on root competition in alley cropping was carried out in an agroforestry system, involving Cassia siamea Lam. and maize ( Zea mays L. cv. Katumani composite B). The existence and intensity of root competition in the top soil as manifested by the distribution of the active roots of cassia and maize, in space and time, was assessed. The root length density of maize was far greater than that of cassia in the upper 10 cm, implying that cassia was not competing with maize for water and/or nutrients at that depth. However, at maize crop tasselling and grain filling stages there was a marked overlap of roots of the two plants at lower depths (20—50 cm). This varied with distance from the cassia hedge in a way that there was a tendency for highest overlap near middle maize rows. This partly explained observed yield differences. Therefore cassia may not be a suitable choice for alley cropping with maize under semi-arid conditions on non-sloping land, unless most of its active roots can be properly managed to absorb resources below the feeding rhizosphere of the active maize roots.     

非色散原子荧光光谱法测定地质试样中的金

<正> 火焰原子吸收光谱法已广泛用来测定各类试样中的金。然而,要在许多地球化学勘探试样的酸分解溶液中进行金的直接测定,该法还不够灵敏。使用碳棒或炉原子化技术可使灵敏度得到显著改善,但是,岩石和土壤试样中通     

Environmental input-output model and its analysis with a focus on the solid waste management sectors

ＩｎｔｒｏｄｕｃｔｉｏｎＳｉｎｃｅｔｈｅｆｉｒｓｔｅｎｖｉｒｏｎｍｅｎｔａｌｉｎｐｕｔｏｕｔｐｕｔｍｏｄｅｌ(ＥＩＯＭ)(Ｃｕｍｂｅｒｌａｎｄ,1966)ｗａｓｅｓｔａｂｌｉｓｈｅｄｂｙｉｎｃｏｒｐｏｒａｔｉｎｇｅｎｖｉｒｏｎｍｅｎｔａｌｆａｃｔｏｒｓｉｎｔ?..     

加拿大制浆造纸废水厌氧处理的进展

1960～980年间,加拿大用于清除制浆造纸工业污染的经费约达6.6亿美元。采取这些措施后,到1980年加拿大72％的制浆造纸厂达到了国家控制废水BOD排放的规定。进一步改进达标状况的措施之一是对许多新制浆厂的高浓度废水采用厌氧处理技术。但需首先要了解制浆造纸工业在采用厌氧技术以前,在几方面的数据(表1)。 1.制浆造纸废水的适应性、生化可降解性及毒性     

酸雨的大气物理化学机理

1.输送过程中的化学转化对北美洲雨水样品的分析表明:雨水的酸度在很大程度上取决于它的硫酸盐和硝酸盐离子浓度,因此本文将着重讨论这两种污染物的形成过程。虽然,大气中有少量的硫酸盐和硝酸盐是被直接排放出来的,但据认为,降雨中这两种盐类的主要来源是硫氧化物和氮氧化物的进一步氧化。然而在燃油发电厂和炼油厂附近,硫酸盐的直接排放量还是较大的。由上述情况可以看出,了解排放点和接受点之间排