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191.
为了探讨粉煤灰对重金属钼的吸附影响因素及吸附机理,以粉煤灰为吸附剂,钼酸铵为吸附质,通过单因子试验分别考察粉煤灰粒径、粉煤灰投加量、吸附时间、pH和温度等因素对吸附效果的影响,确定了粉煤灰吸附的最佳条件(粒径为80~100目,投加量为2.5 g,吸附时间为30 min,pH为3,温度为30 ℃)。在此条件下,粉煤灰对钼酸铵的去除率达到80%~85%。分别用纯水以及0.01,0.05,0.10 mol/L的NaOH和0.05 mol/L的NaCl对最佳吸附条件下的粉煤灰进行解吸试验,结果表明,在粉煤灰的吸附过程中,化学吸附作用大于物理吸附。 相似文献
192.
There is substantial variation in individual preferences for public goods, yet much of that variation remains poorly understood. However, simple measures of personality can help to explain economic values and choices in a systematic way. In this paper, we examine the effects of personality on individual economic choices over public environmental goods. Based on three datasets from three separate stated preference studies, we use a hybrid choice econometric framework to examine the effects of personality on preferences for the status quo, changes in environmental quality, and costs of investing in environmental improvements. We find effects that are consistent across all datasets. Personality, a stable feature of an individual's character that is simple to measure, enriches explanations of why the demand for environmental goods varies across people, provides an indication of how different people are likely to react to the introduction of environmental policies, and explains substantial differences in Willingness to Pay. 相似文献
193.
蒙德法与道化法的选取 总被引:12,自引:0,他引:12
梁庆棠 《中国安全科学学报》2000,10(4):55-58
运用蒙德法和道化法 ,对煤气发生系统评价单元进行安全评价 ,指出两者在进行火灾、爆炸的危险评价时 ,其结论基本上是接近的 ,但仍保持着各自的特点。在此基础上 ,笔者提出 :当评价单元要求在火灾、爆炸、毒性危险因素有更全面的反映时 ,宜采用蒙德法 ;对影响范围、损失情况有具体反映和进行项目预评价时 ,可采用道化法的建议。 相似文献
194.
长期施肥对水稻土耕层微生物生物量氮和有机氮组分的影响 总被引:8,自引:2,他引:6
以亚热带2个国家级稻田土壤肥力变化长期定位监测点的土样为对象,研究了长期施肥对土壤微生物生物量氮(BN)和有机氮组分的影响.采用氯仿熏蒸-K2SO4提取法和酸水解-蒸馏法分别对耕层土壤微生物生物量氮和有机氮组分进行了测定.结果表明,经过17a的有机无机肥配合施用,土壤氮含量水平较低的宁乡点,土壤全氮平均每年增加约40 mg·kg-1,而土壤氮含量水平较高的南县点,平均每年增加约55 mg·kg-1.有机无机肥长期配合施用也提高了土壤微生物生物量氮和微生物生物量氮占全氮的比例;同时也显著增加酸解性氮及氨基酸态氮、酸解未知氮的含量.此外,土壤酸解性氮及其组分均与微生物生物量氮存在极显著的正相关关系,其中氨基酸态氮和酸解未知氮对微生物生物量氮的影响最大.研究表明,有机无机肥配施是使稻田土壤氮素含量提高的重要措施,有机无机肥配施促进了土壤氮库的积累,即易矿化和较难矿化2部分氮库同时增加. 相似文献
195.
196.
Vicente L. Lopes Adrian L. Vogl 《Journal of the American Water Resources Association》2008,44(5):1284-1294
Abstract: Determining watershed response to vegetation treatment has been the subject of numerous hydrologic studies over the years. However, generalizing the information obtained from traditional paired‐watershed studies to other watersheds in a region is problematic because of the empirical nature of such studies and the context dependence of hydrologic responses. This paper addresses the issue of generalizing hydrologic information through integration of process‐based modeling and field observations from small‐scale watershed experiments. To this end, the results from application of a process‐based model were compared with the results from small‐scale watershed experiments in ponderosa pine forests of Arizona. The model simulated treatment impacts reasonably well when compared to the traditional paired‐watershed approach. However, the model tended to overestimate water yields during periods of low flow, and there was a significant difference between the two approaches in the estimation of treatment impacts during the first four years following treatment. The results indicate that the lumped‐parameter modeling approach used here may be limited in its ability to detect small changes, and tends to overestimate changes that occur immediately following treatment. It is concluded that watershed experiments can be highly informative due to their direct examination of cause‐effect relationships, while process‐based models are useful for their processing power and focus on functional relationships. The integrated use of both watershed experiments and process‐based models provides a way to generalize hydrologic information, illuminate the processes behind landscape treatment effects, and to generate and test hypotheses. 相似文献
197.
Ali Ercan M. Levent Kavvas Kara Carr Zachary Hockett Hossein Bandeh Timothy D. Mussen Dennis Cocherell Jamilynn B. Poletto Joseph J. Cech Jr. Nann A. Fangue 《Journal of the American Water Resources Association》2017,53(2):431-441
Most of the water diversions on the Sacramento and San Joaquin Rivers (California, United States) and their tributaries are currently unscreened. These unscreened diversions are commonly used for irrigation and are potentially harmful to migrating and resident fishes. A large flume (test section: 18.29 m long, 3.05 m wide and 3.20 m high) was used to investigate the hydraulic fields near an unscreened water diversion under ecologically and hydraulically relevant diversion rates and channel flow characteristics. We investigated all combinations of three diversion rates (0.28, 0.42, and 0.57 m3/s) and three sweeping velocities (0.15, 0.38, and 0.61 m/s), with one additional test at 0.71 m3/s and 0.15 m/s. We measured the three‐dimensional velocity field at seven cross sections near a diversion pipe and constructed regression equations of the observed maximum velocities near the pipe. Because the velocity components in three directions (longitudinal, transverse, and vertical) were significantly greater near the diversion pipe inlet compared with those farther from it, they cannot be neglected in the modeling and design of fish guidance and protection devices for diversion pipes. Our results should be of great value in quantifying the hydraulic fields that are formed around fish guidance devices to design more effective protection for fishes from entrainment into unscreened water‐diversion pipes. 相似文献
198.
基于选择实验法的支付意愿研究——以湘江水污染治理为例 总被引:5,自引:0,他引:5
论述了选择实验法的理论基础,运用该方法对湘江水污染治理中居民的支付意愿进行了实证分析,以此推断实施湘江流域水污染治理工程后湘江流域水质好转带来的环境价值。选择在湘江流域的八大城市布点,获取了587份居民的调查问卷数据资料。通过计量经济学分析,得到如果实施湘江流域水污染治理工程、彻底解决湘江重金属污染问题,水质完全达到或优于Ⅱ类水标准,湘江流域居民总的支付意愿为1074亿元。 相似文献
199.
In Europe more than 2,500 lysimeters operated by research institutes and industry (Lanthaler 2005). Originally lysimeters
were built for investigations of soil water and solutes, nutrient leaching and pesticide degradation (see e.g. Winton and
Weber 1996). Currently lysimeters additionally used as a tool for investigations on biological processes, and structural changes
of plants, including root distribution, and enzyme activities etc. (see e.g. Dizer et al. 2002; Schloter et al. 2005). 相似文献
200.
Wei Fan Qi Li Mingxin Huo Xiaoyu Wang Shanshan Lin 《Frontiers of Environmental Science & Engineering》2020,14(4):63