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641.
针对我国城市内河污染日益严重的问题,以巢湖市老城区环城河为研究对象,拟定调水方案,进行调水试验。依据沿河水文水质情况,布设6个实时水质监测点,并将环城河概化为5个河段。应用测得的水文水质数据对各河段不同时间点的含氮污染物负荷进行估算,初步研究了各河段NH3-N、TN负荷量的变化规律。通过对比上下游各河段含氮污染物负荷去除效果,分析调水效果的影响因素,总结个别河段调水效果不佳的原因,提出4条优化意见。并结合实际情况,选取其中可行性较强的1条对其有效性进行实验验证。  相似文献   
642.
To provide information on reclamation of multi-heavy metal polluted soils with conception of phytostabilization, a field survey on the uptake and accumulation of potentially toxic elements such as antimony (Sb), arsenic (As), lead (Pb), cadmium (Cd), copper (Cu), and zinc (Zn) in colonized plant species around the world’s largest antimony mine area, China, was conducted. Samples including leaves and shoots (including roots and stems) of colonized plants as well as rhizospheric soils were collected from eight sampling zones in the studied area. The results showed that the contents of Cu, Zn, and Pb in rhizospheric soils below plants were comparable to the corresponding background values of Hunan province, otherwise Sb, Cd, and As contents were extremely high (17–106, 17–87, and 3–7 times of the corresponding background values). The highest concentration of Sb was found in Aster subulatus (410 mg kg?1); Cd, As, and Zn were in Herba bidentis bipinnatae (10.9, 264, and 265 mg kg?1, respectively); and Cu was in Artemisia lavandulaefolia (27.1 mg kg?1). It also exhibited that all the contents of As in leaves were several times of those in shoots of plants, Cd and other heavy metals showed in a similar pattern in several studied species, implying that the uptake route of these heavy metals via foliar might contribute to the accumulation. With high bioconcentration factors of heavy metals (more than 1, except for Zn), together with the growth abundance, Herba bidentis bipinnatae was considered as the most suitable colonized species for phytostabilization of the multi-heavy metal pollution in soils on this antimony mine area.  相似文献   
643.
The study focused on the analysis of the chemical constituents of ethyl acetate extracts of Penicillium herquei, an endophyte of Cordyceps sinensis. The compounds were isolated and purified by chromatographic procedures and identified on the basis of spectral methods. Eleven compounds were identified: 2′,4′-dihydroxy-3′,5′-dimethylacetophenone (1), vanillin (2), 3-oxo-α-ionone (3), 3,3,5-trimethyl-4-(3-oxo-1-butenyl)cyclohexan-1-one (4), p-hydroxybenzaldehyde (5), p-hydroxyacetophenone (6), methyl p-hydroxyphenylacetate (7), cyclo-(Pro-Ile) (8), cyclo-(Pro-Val) (9), 4-methoxyphenylacetic acid (10), and cyclo-(4-methyl-Pro-Val) (11). Benzaldehydes, ionones, and cyclodipeptides are the major metabolites of the P. herquei from C. sinensis. © 2018 Science Press. All rights reserved.  相似文献   
644.
Environmental Chemistry Letters - Membrane separation technology has become one of the most frequently used techniques to secure adequate water resources for human consumption and other...  相似文献   
645.
种子发芽和根伸长毒性试验是研究和评价新化学物质对陆生生物危害性的重要手段之一。为探究在标准化测试中能否使用非推荐基质,以及使用推荐基质时能否用灭菌法替代酸洗法处理石英砂,选取8种植物种子在5种基质中进行试验。结果表明,不同基质对种子发芽率的影响较小,但基质较低的养分含量和特殊的物理结构易对部分种子根长形成胁迫,甚至直接制约根系发育。生菜、水稻在5种基质中的发芽率和根长无显著性差异;绿豆、甘蓝、西瓜在酸洗石英砂中的根长分别为25.1、24.5、29.0 mm,在其余4种基质中根长显著缩短;青瓜在吸水纸和发芽纸中发芽率偏低,仅为83.3%;玉米在酸洗石英砂和灭菌石英砂中的发芽率和根长无明显差异,为100%/45.7 mm和93.3%/44.8 mm,其他基质中显著偏低。标准化测试条件下,以推荐的酸洗石英砂上各种子的发芽率和根长为评判依据,生菜和水稻试验可使用本研究中任意基质,绿豆、甘蓝和西瓜试验仅可使用酸洗石英砂作为基质,青瓜和玉米试验可使用干热灭菌法替代酸洗法处理石英砂,并且青瓜试验还可使用滤纸基质。以上结果为测试机构在工作实践中优化试验条件提供理论依据。  相似文献   
646.
为了较好地分析水-岩作用下库岸边坡消落带岩体的劣化机理,设计进行了考虑库水压力升降变化和浸泡-风干循环的水-岩作用试验。研究结果表明:(1)在水-岩作用过程中,砂岩的单轴抗压强度劣化趋势明显,其中前6期抗压强度劣化趋势较为显著,6次水-岩作用之后,岩样的强度劣化趋势逐渐趋于缓慢。(2)随着水-岩作用周期的增加,岩石内部孔隙、裂隙逐渐发育、汇集,矿物颗粒逐渐软化、分解,使得岩石微观结构逐渐趋于松散。(3)水-岩作用下砂岩劣化的进程中,首先是岩样中胶结物的溶解、溶蚀,然后是失去胶结物包裹的矿物颗粒表面发生水-岩物理化学作用,最后是矿物颗粒本身软化、分解。(4)水-岩作用过程中,岩样内部胶结物的溶解、溶蚀对水-岩作用前期的宏观力学性质影响明显,岩石矿物颗粒本身的软化、分解对水-岩作用后期的力学性质影响明显。相关研究成果可为库岸边坡消落带水-岩作用机理分析提供较好的参考。  相似文献   
647.
Specific second-order rate constants were determined for 5-FU and CAP with ozone. Reaction sites were confirmed by kinetics, Fukui analysis, and products. The olefin moiety was the main ozone reaction site for 5-FU and CAP. Carboxylic acids comprised most of the residual TOC for 5-FU. Ozonation removed the toxicity associated with 5-FU and products but not CAP. Anticancer drugs (ADs) have been detected in the environment and represent a risk to aquatic organisms, necessitating AD removal in drinking water and wastewater treatment. In this study, ozonation of the most commonly used antimetabolite ADs, namely 5-fluorouracil (5-FU) and its prodrug capecitabine (CAP), was investigated to determine reaction kinetics, oxidation mechanisms, and residual toxicity. The specific second-order rate constants between aqueous ozone and 5-FU, 5-FU, 5-FU2, CAP, and CAP were determined to be 7.07(±0.11)×104 M1·s1, 1.36(±0.06)×106 M1·s1, 2.62(±0.17)×107 M1·s1, 9.69(±0.08)×103 M1·s1, and 4.28(±0.07)×105 M1·s1, respectively; furthermore, the second-order rate constants for OH reaction with 5-FU and CAP at pH 7 were determined to be 1.85(±0.20)×109 M1·s1 and 9.95(±0.26)×109 M1·s1, respectively. Density functional theory was used to predict the main ozone reaction sites of 5-FU (olefin) and CAP (olefin and deprotonated secondary amine), and these mechanisms were supported by the identified transformation products. Carboxylic acids constituted a majority of the residual organic matter for 5-FU ozonation; however, carboxylic acids and aldehydes were important components of the residual organic matter generated by CAP. Ozone removed the toxicity of 5-FU to Vibrio fischeri, but the residual toxicity of ozonated CAP solutions exhibited an initial increase before subsequent removal. Ultimately, these results suggest that ozone is a suitable technology for treatment of 5-FU and CAP, although the residual toxicity of transformation products must be carefully considered.  相似文献   
648.
以H3PO4为活化剂制备甘蔗叶活性炭,采用正交实验对活性炭的制备工艺进行了优化,并研究了活性炭对含铬废水的吸附和再生性能.实验结果表明:在H3PO4体积分数为15%、H2SO4体积分数为6%、HC1体积分数为3%、活化温度为723 K、活化时间为0.58 h的工艺条件下,活性炭得率为35.07%,碘吸附值为1 207 mg/g.活性炭对Cr(Ⅵ)的最大平衡吸附量为30.89 mg/g,HNO3再生后对Cr(Ⅵ)的最大平衡吸附量为39.48 mg/g;再生效率最高达87.41%,经3次再生,活性炭的再生效率仍能维持在80%以上.  相似文献   
649.
Zhu Z  Deng Q  Zhou H  Ouyang T  Kuang Y  Huang N  Qiao Y 《Ambio》2002,31(3):226-230
The Pearl River Delta Economic Zone is the most dynamic economic area in South China. One of the major problems in the region is the sustainable utilization of the water resources. On the basis of analysis of the water environment status and pollution sources, it is suggested that domestic sewage is the primary cause of pollution. Two new concepts "degradation coefficient" and "degradation volume" of water resources, due to pollution, which may be used to assess macroscopically the carrying capacity of the water resources and sustainability of the water environment, are proposed by the authors. The results calculated indicate that the volumes of degraded water resources will be up to 204, 352, and 537 million m3 in 2002, 2010, and 2020. It is suggested that water for daily consumption and domestic sewage must be controlled more effectively and there should be cross-regional coordination in tackling problems of water environment.  相似文献   
650.
本文通过在模拟瘤胃发酵装置内进行动物体外瘤胃菌丛发酵生态条件动态变化对细菌数量和菌群的影响研究,发现温度40℃、每小时搅动20分钟是90523-1瘤胃菌丛的最佳生长条件。瘤胃球菌随C/N的减小而增加,而C/N高的条件下更有利于弧菌的生长。  相似文献   
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