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811.
湖泊水环境是一个受多种不确定性因素限制的复杂系统。以内蒙古乌梁素海为研究对象,应用水质超标灰色-随机风险率的计算方法和系统可靠性分析理论建立了单项参数评价模型和综合参数评价模型,分析湖泊入口断面水质存在的潜在风险性。结果表明:乌梁素海镉的Ⅴ类达标率仅为7.69%~23.89%,镉污染已经十分严重,硫化物和氰化物的Ⅲ类和Ⅴ类达标率都达到100%,所以几乎不受这两项指标的污染。该方法能较好地反映乌梁素海入口断面不同水质参数的污染强度和污染历时的变异过程,为湖泊水环境风险的决策和管理工作提供了参考依据。 相似文献
812.
813.
The population genetic structure of the neon damselfish (Pomacentrus coelestis) in the northwestern Pacific Ocean was revealed by the hypervariable control region of the mitochondrial gene (343 bp). In
total, 170 individuals were sampled from 8 localities distributed between Taiwan and Japan, and 71 haplotypes were obtained
through sequence alignment. High haplotype diversity (h = 0.956 ± 0.008) with low nucleotide diversity (π = 0.010 ± 0.006) was observed, and the results of the mismatch distribution test suggested that a historical population expansion
after a period of population bottleneck might have occurred among P. coelestis populations. Based on the results of the UPGMA tree and AMOVA (Φct = 0.193, P < 0.05) analyses, fish populations from eight localities could be divided into two groups: one includes populations from localities
around mainland Japan, and the other includes those from Okinawa and southern Taiwan. A genetic break was found between populations
from mainland Japan and Okinawa, and this break was congruent with the pattern of phenotypic variations documented in previous
studies. This evidence supports the latitudinal variation of reproductive traits among P. coelestis populations likely being genetically based. It is suggested that the changes in sea level and sea surface temperatures during
past glaciations might have resulted in population bottlenecks in P. coelestis and the modern populations in the northern West Pacific are likely the results of recolonization after such events. The Kuroshio
Current acts not only as a vehicle for larval transport along its pathway (between populations in southern Taiwan and Okinawa)
but also as a barrier for larval dispersal across the Kuroshio axis (between populations in mainland Japan and Okinawa).
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users. 相似文献
814.
This study focused on the sorption isotherms of 1,1,1-trichloro-2,2-bis(p-chlorophenyl) ethane (p,p'-DDT) and 1,1-dichloro-2,2-bis(p-chlorophenyl) ethylene (p,p'-DDE) on different original clays (i.e., zeolite, montmorillonite and attapulgite) and organoclay complexes. Sorption of organic pollutants was determined using gas chromatographic (GC) techniques to investigate the sorption behavior, and characterize the effect of, different organic cations. The original clays only sorbed low amounts of p,p'-DDT and p,p'-DDE, and the sorptive curves can be classified as L-shaped. Organoclays exhibited higher amounts of p,p'-DDT and p,p'-DDE sorption. The p,p'-DDT and p,p'-DDE sorption increased with increasing total organic carbon (OC) content of the organoclays. For hexadecyltrimethylammonium (HDTMA)-modified organoclays, the dominant adsorptive medium showed the partitioning sorption of hydrophobic-hydrophobic interaction, indicating no competitive sorption. The sorptive curves can be classified as C-shaped of constant partition (CP). However, benzyltrimethylammonium (BTMA)-modified organoclays exhibited competitive sorption. The sorption isotherm curves can be classified as S-shaped. The sorptive capacity of the HDTMA-modified organoclays for p,p'-DDT were higher than those for p,p'-DDE, but the BTMA-modified organoclays showed a reverse trend. This can be attributed to the different structures and shapes of organic cations, giving different sorptive mechanisms. The p,p'-DDT and p,p'-DDE sorption onto HDTMA-modified organoclays were caused by chemical interaction, with the BTMA modified organoclays occuring due to physical sorption. 相似文献
815.
Laboratory incubation trials were conducted to investigate the effects of several factors on the persistence as well as the
dissipation of three synthetic pyrethroid pesticides in red soils obtained from the Yangtze River Delta region in China. The
pyrethroids selected for investigation were cypermethrin, fenvalerate, and deltamethrin, which continue to be used extensively
to control pests on farmland in the region despite the concern that they are highly toxic to certain vertebrate and mammalian
species. Data from this exploratory study showed that the dissipation half-lives (T
1/2) tended to correlate with soil pH and soil organic matter contents, but not with soil cation-exchange capacity. The T
1/2 values were seen to be shorter in soil samples fertilized with glucose than without. The rates of pyrethroid dissipation
also tended to increase with increasing initial soil concentration, but were largely unaffected by whether the pesticides
were present in the soil separately or as a mixture. Another noteworthy observation is that microbial activity appeared to
dominate the degradation process. Findings of this type could offer valuable clues for future research directions in reducing
pesticide persistence in soil, which in turn could lead to the ultimate reduction of environmental pollution caused by pyrethroid
application to farmland in the region.
Project supported by Chinese Academy of Sciences (Project No. KSCX2-YW-N-038) and the National Key Basic Research Support
Foundation (973), China (No. 2002CB4108010). 相似文献
816.
概述在市场经济条件下,黑龙江省大兴安岭地区劳动卫生和生活环境存在的问题,以及应用系统工程方法论解决存在问题应注意的事项. 相似文献
817.
憎水性污染物在表面活性剂溶液中的增溶动力学 总被引:5,自引:1,他引:4
为了解表面活性剂溶液对憎水性污染物增溶过程的影响因素,研究六氯乙烷在Tween20溶液中的增溶动力学过程,建立了六氯乙烷在表面活性剂溶液中增溶的传质模型.模型表明当六氯乙烷总表面积固定时,其溶解速率同六氯乙烷在表面活性剂溶液中的表观溶解度和表观传质系数呈正相关.发现六氯乙烷在表面活性剂溶液中的表观传质系数和纯水中的相比降低了,但由于表面活性剂对六氯乙烷的增溶作用导致其溶解速率总体上是提高的 相似文献
818.
无机离子SO42-对小麦幼苗积累稀土的影响 总被引:3,自引:0,他引:3
采用MINTEQA 程序计算出在无机离子SO42-存在下,轻(La)、中(Gd)、重(Y)3 种稀土元素在溶液中的形态分布.研究了在水培条件下SOSO42-对3种稀土元素在小麦幼苗根、茎和叶部的积累规律.热力学实验表明,小麦幼苗在加SO42-的稀土元素溶液中培养30d 后,小麦根部对La、Gd 的积累受抑制,而对Y的积累却明显提高;加入SO42-后茎叶部对La、Y积累值改变不明显,但对Gd的积累有所增加.生长动态实验表明,在SO42-存在下,小麦幼苗根部对稀土的积累随时间增加而增加,其积累值符合线性递增函数方程,相关系数r> 0.94;而茎叶部最初积累能力较强,SO42-的加入对小麦植株动态吸收稀土规律无明显影响. 相似文献
819.
Yafang Shi Yunchao Dai Ziwen Liu Xiaofeng Nie Song Zhao Chi Zhang Hanzhong Jia 《Frontiers of Environmental Science & Engineering》2020,14(6):106
820.