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441.
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ABSTRACT. Silver iodide is currently the most favored cloud seeding material in weather modification projects. While the literature indicates that its ecological effects are likely to be insignificant, its disposition in the terrestrial ecosystem after snow melt has not been adequately studied. Silver levels in soil, plant and litter material are being monitored twice a year on a mountainous area in southwestern Colorado, to determine whether annual accretion from cloud seeding can be measured with current techniques and whether significant changes in silver concentration take place in grass, aspen, and spruce communities. One AgI generator site is also being monitored. Comparison of silver concentrations in terrestrial components of the target area indicates no measurable increase after the first winter's seeding. On an ash basis, spruce foliage and litter contain about four times as much silver as soil. On a dry weight basis, soil from all three plant communities contains about six times as much silver as foliage. Consistent increases in silver concentration were found in soil and pine foliage within 200 meters of one generator site. 相似文献
443.
将工业废弃物锰矿尾渣与壳聚糖混合制得一种高效吸附斛,并应用扫描电镜、X射线衍射对其结构进行了表征。采用正交表设计试验,分别考察了pH值、吸附时间、温度、复合吸附剂的投加量等4个影响因素对Pb^2+吸附的影响,最佳吸附条件为:pH值为7,吸附时问为40mjn,温度为20℃,复合吸附剂的投加量为0.10g。处理后的水符合国家污水综合排放标准(GB8978.1996)中的一级标准。复合吸附剂对Pb^2+的吸附符合Langmuir和Freundlich吸附等温方程。 相似文献
444.
Patrick Squires 《Journal of the American Water Resources Association》1971,7(5):951-955
ABSTRACT. A review of the development of weather modification to augment precipitation including the cloud-physical foundation is presented. Recent work has tended to re-emphasize the importance of physical understanding of storm systems and of the effects of cloud seeding. The Pyramid Lake Seeding Project is discussed. 相似文献
445.
表面改性,即对固体的表面进行处理,改变其表面性质,以达到我们需要的理想结果。研究表面性质的方法就是引入某种“探针”考察它与表面的相互作用,通过这种方法对改性前后的样品进行表征。现以催化剂载体表面、电极材料表面及塑料表面为例对表面改性的最新研究进展进行概述。 相似文献
446.
Coastal environments in Australia are under development pressures. Human settlement encroaches on disease vector salt marsh mosquito breeding areas that are underlain by potential acid sulfate soils (PASS). Altering the hydrology by runneling solves the mosquito problem but may lead to acid sulfate problems. Appropriate analytical tools can assess the risk to the environment. The objective of the research was to compare three methods of assessing PASS. The study area was a low-lying intertidal subtropical salt marsh that was being considered for runneling. The results indicated that using field pH and field peroxide pH (and the relationship between these), and also the peroxide oxidation-combined acidity and sulfate (POCAS) test, appeared to overestimate the potential acidity. This was because the source of acidity in the intertidal salt marsh includes a large organic content, which is not a major environmental concern. The chromium-reducible sulfur test, which is not affected by organic content, was found to provide the most appropriate assessment, and is recommended for use in highly organic salt marshes. 相似文献
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利用化学吸附法合成了水杨酸和5-磺基-水杨酸表面修饰的TiO2纳米粒子.对表面修饰前后的TiO2纳米粒子,采用红外光谱法、固体紫外-可见漫反射电子光谱法比较其官能团和吸光性能的变化.研究发现,经水杨酸和5-磺基-水杨酸改性后的TiO2分别呈浅黄色、土黄色,吸收带边发生了明显的红移,吸收边起始点分别延伸至420nm和450nm处,出现-COOTi-和芳香羧酸酯的特征吸收峰;这说明TiO2表面羟基与水杨酸或5-磺基-水杨酸间发生类似酸和醇之闻的酯化反应,分别形成的稳定六元环化合物;在最佳吸附pH值4.0和吸附平衡时闻100min的条件下,水杨酸和5碱基-水杨酸表面修饰的TiO2纳米粒子对硝基苯酚的吸附率可由改性前的43%分别提高至89%和94%,突破了TiO2吸附去除芳香族污染物的瓶颈——在吸附剂表面的低覆盖率;同时表层链接苯环的极性减弱,非极性增强,并在水、苯和乙醇中具有良好的分散性. 相似文献
449.
450.