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921.
Mingteh Chang Christopher M. Crowley Ahmad A. Nuruddin 《Resources, Conservation and Recycling》1995,13(3-4)
A greenhouse study was conducted to evaluate the response of herbaceous mimosa (Mimosa strigillosa) to six levels of cyclic soil moisture stresses in a 17-week period. The results showed that the cultivar continued to grow and the biomass continued to increase even when the soil moisture stress was as high as at the wilting point (1500 Kpa). Also, transpiration recovery rate was quick and values of root/shoot ratio were high when the plant was subject to the cyclic moisture stress condition. All these characteristics, along with strong rooting and spreading ability, suggest this legume as a promising drought hardiness species for reclamation purposes. 相似文献
922.
Poul Johansen Martin Munk Hansen Gert Asmund Palle Bo Nielsen 《Chemistry and Ecology》1991,5(1):35-55
In monitoring the impact of a lead-zinc mine in Greenland, species of fish, prawns, seaweed and mussels have been analysed for cadmium, copper, lead and zinc for several years. These metals have been released to the marine environment in significant amounts from the mining operation. 相似文献
923.
马驹如 《中国人口.资源与环境》1994,4(2):57-59
生物多样性是人类社会赖以生存和发展的基础,生物多样性保护已是当今人们最为关注的热点问题。越来越多的人认识到,生物资源是有限度的。实践表明,为保护物种栖息地而划定和管理的各种区域,对保护生物多样性有着重要的意义。在我国自然保护区被视为最典型和最有代表性的区域,也是生物多样性保护的重要基地。自然保护区保护着国家珍贵的动植物资源,拯救了濒危物种,保护了典型的生态环境,建设自然保护区是自然保护行之有效的手段。 相似文献
924.
925.
Zhan Manjun Yang Xi Yang Hongshen Kong Lingren 《Frontiers of Environmental Science & Engineering in China》2007,1(3):311-315
The photochemical degradation of bisphenol A (BPA) was studied in the presence of natural humic substances from different
origins under simulated solar irradiation. BPA underwent insignificant direct photolysis in neutral water, but rapid photosensitized
degradation in four humic substances solutions via pseudo-first-order reaction occurred. The photo-degradation rate of BPA
was insensitive to the different initial BPA concentrations and was inhibited in aerated solution compared with the deoxygenated
medium. The reactive oxygen species (ROS) such as ·OH and 1O2 produced from excitation of humic substances under irradiation was determined from the quenching kinetic experiment using
molecular probe. The five main intermediate photoproducts of BPA in Nordic lake fulvic acid (NOFA) were tentatively identified
using gas chromatography/mass spectrometer (GC/MS). Based on the identification of ROS and the analysis of photoproduct formation,
the possible phototransformation pathways of BPA were proposed, involving the direct photolysis due to the energy transfer
from the triplet state humic substance (3HS*) to BPA molecules and hydroxyl radical addition and oxidation as well.
Translated from Acta Scientiae Circumstantiae, 2005, 25(6): 816–820 [译自: 环境科学学报] 相似文献
926.
Lu Sihua Liu Ying Shao Min Huang Shan 《Frontiers of Environmental Science & Engineering in China》2007,1(2):147-152
Volatile organic compounds (VOCs) were measured at six sites in Beijing in August, 2004. Up to 148 VOC species, including
C3 to C12 alkanes, C3 to C11 alkenes, C6 to C12 aromatics, and halogenated hydrocarbons, were quantified. Although the concentrations differed at the sites, the chemical
compositions were similar, except for the Tongzhou site where aromatics were significantly high in the air. Based on the source
profiles measured from previous studies, the source apportionment of ambient VOCs was preformed by deploying the chemical
mass balance (CMB) model. The results show that urban VOCs are predominant from mobile source emissions, which contribute
more than 50% of the VOCs (in mass concentrations) to ambient air at most sites. Other important sources are gasoline evaporation,
painting, and solvents. The exception is at the Tongzhou site where vehicle exhaust, painting, and solvents have about equal
contribution, around 35% of the ambient VOC concentration. As the receptor model is not valid for deriving the sources of
reactive species, such as isoprene and 1,3-butadiene, other methodologies need to be further explored. 相似文献
927.
通过Al-Ferron逐时络合比色法和 ̄(27)Al核磁共振(NMR)法,并应用“MINEQL”化学平衡模式计算法,对采用不同反应途径制得的聚合铝(PAC)溶液中的化学形态分布规律进行了定量模拟研究和对比。模式计算结果与两种实验定量分析结果都较为吻合,结果表明,在水解聚合铝溶液中较稳定的化学形态主要有五种:一种单体形态[al_a],即Al ̄(3+),Al(OH) ̄(2+),Al(OH)_2 ̄+;3种聚合形态[Al_b],即和以及一种溶胶或凝胶形态[Al_c],即Al(OH)_3(am).这些化学形态的分布和转化不仅取决于溶液的化学特征,而且也取决于制备方法的不同。 相似文献
928.
929.
《环境科学学报(英文版)》2023,35(4):668-682
In the present study, two nanosized MnO2 with β and δ phase structures and potassium loaded MnO2 catalysts with varied K loading amounts (denoted as K/MnO2) were prepared. Temperature programmed oxidation and isothermal reactions in loose contact modes were employed to examine the soot oxidation activity of the as-prepared catalysts. Characterization results show that as compared with β-MnO2, δ-MnO2 has larger surface area and higher content of hydroxyl groups. Upon K loading, abundant hydroxyl groups in δ-MnO2 effectively sequestrate K cation to form bound K species and free K species are available only at K loading above 3.0 wt.%. In contrast, the majority of K species present as free state in β-MnO2 even at a K loading of 1.0 wt.% due to its very low hydroxyl group content. The O2 temperature-programmed desorption (O2-TPD) demonstrates that the catalysts with free K species exhibit strong ability in activating gaseous O2, whereas the catalysts only having bound K display minor O2 activation capability. As a result, despite of slightly lower activity of β-MnO2 than δ-MnO2, the K/β-MnO2 catalysts exhibit substantially higher activities than K/δ-MnO2 catalysts with identical K loadings. The finding in this study clearly demonstrates that for MnO2 based catalysts, the enhancement of catalytic activity for soot oxidation is highly K loading amount dependent and the dependency is strongly associated with the phase structure of MnO2. 相似文献
930.
自然选育酵母菌对不同废水处理及资源化研究 总被引:7,自引:0,他引:7
从色拉油加工废水,味精废水、印染废水、钻井废水等4种特性各异的废水中筛选出酵母菌,并根据形态特征和生理生化特征对筛选到的12种酵母菌(包括2种耐氨酵母)进行了鉴定。结果表明:酵母菌处理工艺对色拉油加工废水和味精废水这两类高浓度有机废水具有较好的处理效率,如前者的TOC和后者的COD的去除率均在85%以上。但对人工合成物质含量较高的印染废水和钻井废水处理效果较差。这一结果可能与酵母菌原来所处的环境条件有关。 相似文献