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131.
无机陶瓷纳滤膜分离高钠盐废水中的锶 总被引:1,自引:0,他引:1
本实验研究表明,仅用截留分子量为1000的无机陶瓷纳滤膜分离高钠盐模拟溶液中的锶,分离效果并不理想。为提高陶瓷纳滤膜对锶的选择分离效果,选择了分子量为3000的聚丙烯酸作为陶瓷纳滤膜分离的强化剂,重点探讨了溶液pH值、聚丙烯酸浓度、温度及离子强度对模拟溶液盐分离效果和膜通量的影响,并得到了适宜的锶钠分离条件。实验结果表明,在适宜条件下,通过聚丙烯酸强化和两级分离,陶瓷纳滤膜可大大提高模拟溶液中锶离子的选择分离效果,锶/钠的分离因子高达205。 相似文献
132.
Monthly variability of Cd, Hg, Zn, Mn and Al concentrations in mussels (Mytilus californianus) soft tissue and brown seaweed (Macrocystis pyrifera) was studied at a pristine rocky shore off San Quintin Bay, Baja California, México. The results were related to climatic and hydrographic conditions and to the physiological state of the mussels (condition index) by correlation analysis and principal component analysis (PCA). A "normalization" to account for the variability induced by the physiological state of the mussel was performed. The PCA was performed in two ways to relate the environmental variables and the condition index to: (1) the metal concentrations in mussels, and (2) the "normalized" mussel concentrations. The association of the variability of Cd with the upwelling season was revealed in both PCAs. The temporal variability of this metal in mussels was highly correlated to that in seaweed, suggesting that the dissolved phase determined the variability of Cd in mussels. However, for Hg, Zn, Mn and Al the results from both PCAs were different. The first PCA showed the relationship of these metals to pluvial precipitation and to the condition index. The PCA for the normalized mussel concentrations showed that, after eliminating the effect of the condition index, only Al was related to pluvial precipitation. Manganese, and to a less degree Zn, were related to these metals in seaweed. Because zinc is an essential element in mussels, some regulation of their internal concentrations is likely. Mercury was not detected in seaweed, but because of its reactive nature, it is not expected that the dissolved fraction could be a significant pathway; therefore, it can be concluded that its temporal variability was determined by the variability in the condition index only. 相似文献
133.
Variability of cadmium, copper and zinc levels in molluscs and associated sediments from Chile 总被引:3,自引:0,他引:3
De Gregori I Pinochet H Gras N Muñoz L 《Environmental pollution (Barking, Essex : 1987)》1996,92(3):359-368
The concentrations of cadmium, copper and zinc in mussel and sediment samples collected together from eight different geographical coastal areas of Chile were determined. The mussels studied were 'Chorito Maico', 'Almejas' and 'Navajuelas Chilenas' (Perumytilus purpuratus, Semelle solida and Tagellus dombeii, respectively). Sampling was carried out in July and September 1992 and January and April 1993 (winter, spring, summer and autumn seasons in Chile, respectively). The metal levels in these mussels varied among species; there were several sites where the metal concentrations in molluscs approached or exceeded the criteria levels for Cd, Cu and Zn in shellfish products: 1, 10 and 50 ppm ww respectively, which are regarded as safe levels for human consumption. The results of metal levels in sediments showed two areas clearly polluted with Cu. Strong relationships between Cu concentrations in the three molluscs and sediments were found; weak correlations were observed for Zn in S. solida. 相似文献
134.
Woodlands of the Mediterranean speciesJuniperus oxycedrus ssp.macrocarpa (maritime juniper) are both vulnerable and ecologically important. Their ecology and biological status along the SW coast
of Spain are not well known; this, the first major study of these juniper populations is a basis for future research and restoration
policies. These communities are subject to harsh conditions, the plant composition being controlled by several factors at
different scales. On a large scale, climate and soil texture play an important role in controlling the soil water availability
to plants, and in separating xerophytic from mesic communities. On a small scale, coastal physiography, and substrate composition
are related to differences in the floristic composition. Coastal plantations modify environmental conditions, such as sand
mobility and salt spray deposition, inducing important changes in plant communities. The population of maritime juniper on
this coast was estimated in ca. 25 000 individuals, of which 93.6% are concentrated in three locations. Large proportions
of young individuals were found in extensive and protected populations. Howerver, adult individuals dominated the smaller
populations located under pine plantations. This limitation of recruitment may be imposed by several factors. A male biased
ratio was detected on the southern coast of Cádiz, which I hypothesize is due to the lower cost of pollen production in a
stressful habitat. Preservation of suitable habitats, the recovery of abandoned pine plantations, and the connection between
juniper populations, seem to be important requisites for the conservation of maritime juniper in the southwestern coast of
Spain. 相似文献
135.
Female preference for dominant males is widespread and it is generally assumed that success in male-male competition reflects high quality. However, male dominance is not always attractive to females. Alternatively, relatively symmetric individuals may experience fitness advantages, but it remains to be determined whether males with more symmetrical secondary sexual traits experience advantages in both intra- and intersexual selection. We analysed the factors that determine dominance status in males of the lizard Lacerta monticola, and their relationship to female mate preference, estimated by the attractiveness of males' scents to females. Sexually dimorphic traits of this lizard (head size and femoral pores) appear to be advanced by different selection pressures. Males with relatively higher heads, which give them advantage in intrasexual contests, were more dominant. However, head size was unimportant to females, which preferred to be in areas marked by relatively heavier males, but also by males more symmetric in their counts of left and right femoral pores. Chemicals arising from the femoral pores and other glands might honestly indicate quality (i.e. related to the symmetry levels) of a male to females and may result from intersexual selection. Females may use this information because the only benefit of mate choice to female lizards may be genetic quality. Chemical signals may be more reliable and have a greater importance in sexual selection processes of lizards than has previously been considered. 相似文献
136.
2005年12月11日是一个普通的周日,伦敦及周边地区沉浸在周末的慵懒之中,一场罕见的灾难发生了.早上6时许,巨大的声响把城市从睡梦中惊醒,惊慌的人们刚开始还以为发生了地震.随着巨响腾空而起的黑烟,将人们的视线牵引到了赫莫尔汉普斯特德镇.在伦敦西北40公里的这座小镇上,有英国第五大油库--邦斯菲尔德油库,该油库负责向英格兰东南部大部分地区提供汽油和燃料用油,莫非是这座油库发生了爆炸,人们的猜测不幸被言中. 相似文献
137.
138.
为查明我国北方沙漠地区降水化学组成及来源,在阿拉善沙漠高原阿右旗气象站采集了2013—2015年的降水样品,测定了降水pH、EC(电导率)及主要离子当量浓度.结果表明:阿拉善沙漠阿右旗气象站降水pH和EC的范围分别为6.66~8.05和35~1 237 μS/cm;Ca2+、SO42-、Na+和Cl-为降水中的主要离子,其总和占总离子的85%以上.降水pH、EC和主要离子当量浓度是反映空气质量的基本参数,较高的降水pH反映出当地降水具有明显的碱性特征.与其他地区相比,该地区降水的EC和可溶性离子日均湿沉降通量也较高,且随月份有较大的变化,表明干旱沙漠粉尘对当地降水水化学的贡献较大.根据离子来源相对贡献的计算结果发现,降水中92.8%的SO42-和98%的NO3-来自人为源,98.8%的Ca2+和88.7%的K+为陆地来源,55%的Mg2+为海洋源,24.8%的Na+来自矿物风化,极少部分Cl-为人为源.研究显示:除降水中的NH4+外,其他主要离子之间的相关性表明各种成因物质在风力作用下同时进入了大气;基于[NH4+](NH4+的当量浓度)与[K+](K+的当量浓度)相关性分析,降水中的NH4+来自生物质燃烧、肥料使用、动物粪便等. 相似文献
139.
Fahe Chai Abdelwahid Mellouki Christian George Yujing Mu Jianmin Chen Hong Li 《环境科学学报(英文版)》2018,30(9):1
正Air pollution as well as climate change and their possible effects on the environment,ecosystems and human health,are pressing challenges.Nowadays,it is clear that sustainable societal development cannot remain solely wealth-oriented,but must take into account the present and future environmental issues.However,this approach is possible only if scientifically sound knowledge in all environmental areas becomes available to our societies and decision makers,which requires a firm 相似文献
140.
为评估污染减排对南京青奥期间空气质量影响,利用排放系数法估算减排量,利用敏感系数分析管控措施有效性.结果表明:经过8月份的强力减排,SO2、NO2、PM2.5、PM10、CO与VOCs减排量分别为3438、4402、3177、7249、15890与4052 t,减排比例分别为-29%、-25%、-45%、-65%、-26%、-22%;环境空气中SO2、NO2、PM2.5、PM10、CO与O3浓度环比7月分别下降了-18.8%、-15.0%、-37.0%、-35.4%、-7.1%与-50.4%;敏感系数排序为:O3>PM2.5>SO2>NO2>PM10>CO,除了O3外,其余污染物浓度下降比例小于减排比例,说明要取得一定空气质量改善,需要付出更多的减排努力. 相似文献