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921.
Jun QIAO Chengdong ZHANG Shuiming LUO Wei CHEN 《Frontiers of Environmental Science & Engineering》2014,8(2):293-304
This study evaluated the effectiveness of different amendments--including a commercial NPK fertilizer, a humic substance (HS), an organic industrial waste (NovoGro), and a yeast-bacteria consortium--in the remediation of highly contaminated (up to 6% of total petroleum hydrocarbons) oilfield soils. The concentrations of hydrocarbon, soil toxicity, physicochemical properties of the soil, microbial population numbers, enzyme activities and microbial community structures were examined during the 90-d incubation. The results showed that the greatest degradation of total petroleum hydro- carbons (TPH) was observed with the biostimulation using mixture of NPK, HS and NovoGro, a treatment scheme that enhanced both dehydrogenase and lipase activities in soil. Introduction of exogenous hydrocarbon-degrading bacteria (in addition to biostimulation with NPK, HS and NovoGro) had negligible effect on the removal of TPH, which was likely due to the competition between exogenous and autochthonous microorganisms. None- theless, the addition of exogenous yeast-bacteria consor- tium significantly enhanced the removal of the aromatic fraction of the petroleum hydrocarbons, thus detoxifying the soil. The effect of bioaugmentation on the removal of more recalcitrant petroleum hydrocarbon fraction was likely due to the synergistic effect of bacteria and fungi. 相似文献
922.
In order to explore the characteristics and species diversity of the vegetation growing in the provenance slope with high-frequency debris flow, we selected the slopes on the north and south sides of the valley in the Jiangjiagou watershed as the research object. The structural characteristics and quantitative compositions of the communities of vegetation growing on different positions of the slopes were investigated. The species composition, important value, species diversity, and ground and underground biomass of the different communities on the slope were statistically analyzed, and the correlations of the ground and underground biomass with the diversity were determined. The results showed that: of the total 49 species found, the herbs were the dominant flora, of which 33 were found on the northern slope and 23 were found on the southern slope. There were significant differences in the species composition and composition of the important values along the different positions on the slope, being mainly affected by the pioneer herbaceous plants. We found that Heteropogon contortus, Eulaliopsis binata, Arthraxon hispidus, and Sesbania cannabina were highly adaptable to debris flow. These four species are common to the area and can be used as the main configuration species for future ecological restoration. There were differences in the community characteristics and species diversity at different positions on the slope. For the southern slope of the valley, the Shannon-Wiener diversity index was in the order: stable zone (2.311) > instable zone (2.161) > deposit zone (2.036), and in the order: deposit zone (2.626) > stable zone (1.338) > instable zone (1.057) for the northern slope. There were significant differences in the biomass, being in the order: stable zone > instable zone > deposit zone, with higher values in the northern slope than in the southern slope. Based on the aforementioned results, we suggest that the restoration of vegetation in the area of the provenance slope having high-frequency debris flow should focus on the prevention and protection of the instable zone of the slope by natural processes of recovery. The deposit zone needs rational remediation measures. We should introduce local shrub and arbor to increase the species composition and promote the development of plant communities with vertical structures. © 2018 Science Press. All rights reserved. 相似文献
923.
Biological effects of nanoparticles have attracted widespread attention. However, the interaction between plants and nanoparticles remains unclear. The purpose of this study was to investigate characteristics of nano-sized metal particles in two representative plant species, Erigeron canadensis and Boehmeria nivea, in the Guangdong Province, China. The stems of the plants were sliced and placed on Ni–C grids for field-emission transmission electron microscopy (TEM). The metal-bearing nanoparticles were further analysed for their size, shape, composition, content and other characteristics using X-ray energy spectrum analysis, scanning TEM and selected-area electron diffraction pattern. The results revealed that the plants contain nano-sized Au-bearing particles with a diameter of 5–50 nm, ellipsoid, spherical and bone-rod shapes or irregular morphology with smooth edges. These nanoparticles primarily consisted of Au, Cu, O and Cl. The discovery of Au-bearing nanoparticles in natural plant tissues is of great significance for biological nanoscience. Here, we discuss the function and absorption mechanism of Au-bearing nanoparticles in plants and present the influence of the discovery of Au-bearing nanoparticles in natural plants. 相似文献
924.
925.
Seasonal pattern of transport pathways and potential sources of PM2.5 in Chengdu during 2012–2013 were investigated based on hourly PM2.5 data, backward trajectories, clustering analysis, potential source contribution function (PSCF), and concentration-weighted trajectory (CWT) method. The annual hourly mean PM2.5 concentration in Chengdu was 97.4 mg·m–3. 5, 5, 5 and 3 mean clusters were generated in four seasons, respectively. Short-distance air masses, which travelled within the Sichuan Basin with no specific source direction and relatively high PM2.5 loadings (>80 mg·m–3) appeared as important pathways in all seasons. These short pathways indicated that emissions from both local and surrounding regions of Chengdu contributed significantly to PM2.5 pollution. The cities in southern Chengdu were major potential sources with PSCF>0.6 and CWT>90 mg·m–3. The northeastern pathway prevailed throughout the year with higher frequency in autumn and winter and lower frequency in spring and summer. In spring, long-range transport from southern Xinjiang was a representative dust invasion path to Chengdu, and the CWT values along the path were 30-60 mg·m–3. Long-range transport was also observed in autumn from southeastern Xinjiang along a northwesterly pathway, and in winter from the Tibetan Plateau along a westerly pathway. In summer, the potential source regions of Chengdu were smaller than those in other seasons, and no long-range transport pathway was observed. Results of PSCF and CWT indicated that regions in Qinghai and Tibet contributed to PM2.5 pollution in Chengdu as well, and their CWT values increased to above 30 mg·m–3 in winter.
相似文献
926.
Weiqi Luo Yanping Ji Lu Qu Zhi Dang Yingying Xie Chengfang Yang Xueqin Tao Jianmin Zhou Guining Lu 《Frontiers of Environmental Science & Engineering》2018,12(3):4
927.
洪水灾害过程中,堤防上游水头快速变化,作用在堤基土体上的水压力是非稳定的。选取常见的堤基砂土作为试验材料,利用自行设计的试验装置,研究洪水灾害时非稳定水头条件下,堤基无黏性土渗径长度、孔隙比、渗透系数以及颗粒粒径等因素对水压力传递滞后效应的影响规律。研究结果表明:土体颗粒粒径越大水压力传递滞后效应越弱,直径>2 mm的细砾土中水压力传递滞后效应基本可以忽略;上游水头水力梯度提升的越快,下游水压力启动和稳定滞后时间越短,但下游水压力恢复滞后时间越长;水压力传递滞后时间与土体孔隙比呈反比关系;下游水压力启动和稳定滞后时间与渗透系数呈对数关系。 相似文献
928.
929.
为研究能量桩的长期工作特性,通过引入Masing准则来建立桩-土荷载传递循环加卸载曲线,进而基于热力荷载传递原理来模拟循环温变荷载作用下能量桩的响应,然后基于现场原位试验,验证模型的可行性,最后研究不同冷热循环方式和桩顶荷载水平对能量桩长期响应的影响。研究结果表明:①循环温变荷载作用会使能量桩桩顶沉降和桩顶轴力不断增大,并最终趋于稳定;②相较于只提供制冷需求的能量桩循环方式,同时提供制冷制热需求的能量桩更容易引起桩顶残余沉降和残余温度应力的持续积累;③相较于桩顶轴力增量,建筑荷载的增大更容易引起桩顶残余沉降的积累。 相似文献
930.
节肢动物蜕皮与N-乙酰-β-D-氨基葡萄糖苷酶(EC3.2.1.52,NAGase)密切相关。为了探究Hg~(2+)和Pb~(2+)这2种重金属离子对节肢动物NAGase的影响,以中国鲎(Tachypleus tridentatus)为材料,从其内脏分离提取了NAGase。利用酶促反应动力学方法,研究Hg~(2+)和Pb~(2+)对中国鲎NAGase的影响;通过对酶荧光发射光谱的测定,研究NAGase酶蛋白经Hg~(2+)和Pb~(2+)作用后的空间构象变化。结果表明,Hg~(2+)和Pb~(2+)对中国鲎NAGase均有较强的抑制作用,Hg~(2+)对NAGase的抑制作用强于Pb~(2+),Hg~(2+)和Pb~(2+)对NAGase的抑制作用均表现为可逆过程,其中Hg~(2+)对NAGase的抑制属于竞争性抑制作用,抑制常数KI为22.68μmol·L~(-1),Hg~(2+)只与游离酶结合,不与酶-底物络合物结合;而Pb~(2+)对NAGase的抑制是属于竞争性-非竞争性混合型抑制作用,抑制常数KI和KIS分别为19.13 mmol·L~(-1)和75.23 mmol·L~(-1),Pb~(2+)与游离酶的亲和力相比与酶-底物络合物的亲和力更强。NAGase经Hg~(2+)和Pb~(2+)作用后荧光发射强度均降低,但荧光发射峰值并没有发生位移,说明Hg~(2+)和Pb~(2+)对中国鲎NAGase的抑制作用均为酶蛋白空间构象的变化所致。这证明了Hg~(2+)和Pb~(2+)对中国鲎NAGase活力具调控作用。 相似文献