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Bernhard Adriaensens 《生态毒理学报》2003,25(3):88-91
某些公司使用基于消费者现有和潜在需求的市场开发和公关战略.另外一些公司则希望制造一个新的世界,提前应对这些趋势并启动新的举措.选择最有勇气路径的企业形成了汇总在下面的几条规则,这反映了他们对可持续发展标准的赞同. 相似文献
124.
Bernhard Adriaensens 《生态毒理学报》2003,(4):88-91
某些公司使用基于消费者现有和潜在需求的市场开发和公关战略.另外一些公司则希望制造一个新的世界,提前应对这些趋势并启动新的举措.选择最有勇气路径的企业形成了汇总在下面的几条规则,这反映了他们对可持续发展标准的赞同. 相似文献
125.
Copper, Lead and Zinc Mobility and Bioavailability in a River Sediment Contaminated with Paint Stripping Residue 总被引:2,自引:0,他引:2
A river embankment sediment beneath a road bridge in South Australia had been surveyed on a previous occasion to a depth of 10 cm and found to contain high levels of copper, lead and zinc deposited during previous lead and zinc-based primer paint stripping operations prior to repainting the bridge. Since the river embankment is geologically different from the surrounding non-embankment soils, and a sufficient distance from the bridge along the river embankment could not be traversed, the geological background Cu, Pb and Zn fraction was established initially using a solid phase sequential extraction (SPSE) procedure. Assessment of the degree of contamination and extent of vertical mobility was then established. Copper was a minor contaminant and present predominantly as the geological background species. Lead was partitioned evenly between the oxalate soluble fraction and residual fraction to a depth of 30 cm with a decrease in total Pb concentration from 497 to 141 mg Pb kg–1 while Zn was predominantly in the oxalate soluble fraction to a depth of 15cm with a decrease in concentration from 1013 to 150 mg Zn kg–1. The reduced rate of nitrification and the lower total concentration of NO3
–-N together with the higher respiratory quotient, combined with the lower microbial quotient, are indicative of microbial stress due to heavy metal toxicity. In the case of Pb and Zn paint stripping residues, these changes in indicators of microbial health are possibly the result of the greater abundance and hence possible bioavailabilty of organo- and chloro-Pb compared to organo- and chloro-Zn complexes. 相似文献
126.
Platinum, palladium, rhodium, iridium and osmium were found to be enriched relative to their expected natural concentrations in peat samples from Thoreau's Bog, an ombrotrophic peat bog in Concord, Massachusetts. The source of osmium into the bog was determined from its isotopic composition (187Os/188Os). Osmium is composed of 4% lithogenic osmium from atmospheric soil dust, 41% of anthropogenic osmium and 55% of osmium from a non-lithogenic, non anthropogenic source, with rain being a likely candidate for the latter. Significant anthropogenic and rain contributions are also expected for iridium. In contrast, platinum, palladium and rhodium are almost exclusively anthropogenic. The larger enrichments of platinum, palladium and rhodium indicate that automobile catalysts are the source of platinum group elements to Thoreau's bog. The bog is located approximately 300 m from a major road and, therefore, the occurrence of platinum elements is evidence for regional dispersion of these metals. The absence of a clear trend following the introduction of catalysts indicates that platinum group elements are not quantitatively conserved in peat with downward leaching and plants playing an important role in the accumulation of platinum group elements. 相似文献
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There is a great interest in ecology in understanding the role of soil microbial diversity for plant productivity and coexistence. Recent research has shown increases in species richness of mutualistic soil fungi, the arbuscular mycorrhizal fungi (AMF), to be related to increases in aboveground productivity of plant communities. However, the impact of AMF richness on plant-plant interactions has not been determined. Moreover, it is unknown whether species-rich AMF communities can act as insurance to maintain productivity in a fluctuating environment (e.g., upon changing soil conditions). We tested the impact of four different AMF taxa and of AMF diversity (no AMF, single AMF taxa, and all four together) on competitive interactions between the legume Trifolium pratense and the grass Lolium multiflorum grown under two different soil conditions of low and high sand content. We hypothesized that more diverse mutualistic interactions (e.g., when four AMF taxa are present) can ease competitive effects between plants, increase plant growth, and maintain plant productivity across different soil environments. We used quantitative PCR to verify that AMF taxa inoculated at the beginning of the experiment were still present at the end. The presence of AMF reduced the competitive inequality between the two plant species by reducing the growth suppression of the legume by the grass. High AMF richness enhanced the combined biomass production of the two plant species and the yield of the legume, particularly in the more productive soil with low sand content. In the less productive (high sand content) soil, the single most effective AMF had an equally beneficial effect on plant productivity as the mixture of four AMF. Since contributions of single AMF to plant productivity varied between both soils, higher AMF richness would be required to maintain plant productivity in heterogeneous environments. Overall this work shows that AMF diversity promotes plant productivity and that AMF diversity can act as insurance to sustain plant productivity under changing environmental conditions. 相似文献
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Segal-Rozenhaimer M Shavit U Vengosh A Gavrieli I Farber E Holtzman R Mayer B Shaviv A 《Journal of environmental quality》2004,33(4):1440-1451
The Lower Jordan River is located in the semiarid area of the Jordan Valley, along the border between Israel and Jordan. The implementation of the water sections of the peace treaty between Israel and Jordan and the countries' commitment to improve the ecological sustainability of the river system require a better understanding of the riverine environment. This paper investigates the sources and transformations of nitrogen compounds in the Lower Jordan River by applying a combination of physical, chemical, isotopic, and mathematical techniques. The source waters of the Lower Jordan River contain sewage, which contributes high ammonium loads to the river. Ammonium concentrations decrease from 20 to 0-5 mg N L(-1) along the first 20 km of the Lower Jordan River, while nitrate concentrations increase from nearly zero to 10-15 mg N L(-1), and delta(15)N (NO(3)) values increase from less than 5 per thousand to 15-20 per thousand. Our data analysis indicates that intensive nitrification occurs along the river, between 5 and 12 km from the Sea of Galilee, while further downstream nitrate concentration increases mostly due to an external subsurface water source that enters the river. 相似文献