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31.
Aquatic plants are used as a practical and effective method to remove toxic metals from secondary-treated municipal wastewater. In this study, Lemna gibba was investigated for its capacity to remove silver (Ag) and gold (Au) from secondary effluents. L. gibba was collected from a natural lake and then acclimatized to the effluent in situ. The concentration of toxic elements in the plant material was monitored as a function of time over 7 days. L. gibba accumulated significant amounts of Ag and Au for six days from initiation of the experimental study. The highest accumulations were 2303% for Ag and 247% for Au. However, after six days, the rate of Ag and Au accumulation in L. gibba declined, as saturation levels had been reached in the plant tissues. The metal accumulating property of L. gibba can also be commercially exploited to recover Au and Ag from wastewater and mining wastes. 相似文献
32.
Strengthening foundations of seismically weak buildings on sandy soils in Denizli,Turkey 总被引：1，自引：0，他引：1
Erdal Akyol 《Environmental Earth Sciences》2012,66(5):1415-1421
Rare earth elements (REE) have been extensively used to indicate for material provenance since they behave conservatively and mainly transport in particulate form during earth surface processes. Nevertheless, the application of REE for material provenance study has to be cautious because grain size and mineral fractionations can alter bulk compositions of weathered sediments. Central Asia is one of the most important dust source regions globally and numerous studies on REE compositions of surface materials have been conducted. In this study, REE compositions of various materials from this area are summarized to explore the existing REE-related problems. Overall, chondrite-normalized REE patterns for many surface materials are so uniform that they cannot serve as reliable approaches in tracing material source regions. In contrast, great variations of REE compositions occur among different materials that are derived even from the same parent rock due to influences of grain-size distributions and heavy minerals. For the same reason, small-scale loess around the Tibetan Plateau has different upper continental crust (UCC)-normalized REE patterns compared to those of typical loess. Therefore, great cautions should be made when UCC-normalized REE patterns and REE ratios are utilized to investigate material provenance. Finally, some suggestions are proposed for such studies in future. 相似文献