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The diatom flora of selected sites in the Animas River Watershed, San Juan County, Colorado, was studied. Eighty diatom taxa were identified from 10 sites: 8 sites on the Animas River and 1 site each on the Cement and Cascade tributaries. The sample diatom abundance was dominated by Achnanthidium minutissimum , Encyonema silesiacum , Aulacoseira distans , Hannaea arcus , and Diatoma mesodon . The presence of teratologic specimens of Fragilaria and Achnanthidium in the samples indicated the possibility of metals contamination. Diatom diversity was low and Lange-Bertalot pollution index scores indicated little organic pollution evidenced from diatom composition. There was evidence that diatom composition at the sites was differentially affected by pH and possibly by the concentrations of Zn alone or in combination with Cd, Cu, and Fe. 相似文献
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Soil samples, one from each of 10 locations in northern Nevada, were evaluated for redox potential, total and extractable selenium, phosphate, free iron oxide, total and ferrous iron. Mole fractions for extractable selenium species were calculated from redox potentials. Data were used to extrapolate general geochemical relationships for soil selenium at the sample sites. Results obtained from one sample per location allowed only the most general conclusions to be drawn. Soil phosphate levels, which affect the adsorption of selenite species on iron oxide by competing for adsorption sites, were not correlated with levels of extractable selenium in this study. This would suggest that selenium would exist in solution, having been displaced from adsorption sites by phosphorous. Ferrous iron, iron oxides, and redox potential had a combined effect on the level of extractable selenium at all sites. Soils in this study support selenite species that are not readily available to plants and therefore could not support vegetation adequate in Se. 相似文献
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Lysolecithin and cell fusion 总被引:24,自引:0,他引:24
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In most populations of mountain goats ( Oreamnos americanus ), mineral lick use is an essential part of the ecology of the species. In many areas, the distribution and use of licks in the landscape is poorly known, rendering planning for resource development difficult. We examined lick use by 28 GPS radio-collared mountain goats in 2 study areas in southeastern British Columbia during 2004–2005. Viewing collar-location movements on digital orthophotos, we assumed goat use of 6 previously known and 10 suspected mineral licks. Field visits verified that 9 of the 10 suspected sites were mineral licks. Thirteen of the 15 licks used by collared goats were within forests with commercial harvesting potential. All but 3 of the licks were ≤600 m from the closest logging block, and 5 licks were <100 m away. Number of annual visits to licks by individual goats ranged from 0 to 9. Goats often moved considerable distances (up to 17.3 km) to visit licks. Most visits by males occurred between early May and late June (median 9 June), and most visits by females occurred between early June and mid-July (median 21 June). Mean time spent at licks on each visit was 1.5 days for females and 1.6 days for males. Most of the licks were characterized by numerous cavities dug under trees (which we term “lick trees”). Using GPS collars, we were able to collect data on lower-elevation mineral licks not previously known to researchers. 相似文献
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GC/MS法追踪摇头丸杂质体系 总被引:1,自引:0,他引:1
本文运用GS/MS的总离子流法,选择离子法,对南京地区常见的几种摇头丸进行全面分析,找出与合成途径相关的痕量杂质,根据杂质情况初步确定其合成途径. 相似文献