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Adsorption of the hydrophobic organic compounds (HOCs) trichloroethylene (TCE), 1,3-dichlorobenzene (DCB), 1,3-dinitrobenzene (DNB) and γ-hexachlorocyclohexane (HCH) on five different carbonaceous materials was compared. The adsorbents included three polymer-based activated carbons, one coal-based activated carbon (F400) and multiwalled carbon nanotubes (MWNT). The polymerbased activated carbons were prepared using KOH activation from waste polymers: polyvinyl chloride (PVC), polyethyleneterephthalate (PET) and tire rubber (TR). Compared with F400 and MWNT, activated carbons derived from PVC and PET exhibited fast adsorption kinetics and high adsorption capacity toward the HOCs, attributed to their extremely large hydrophobic surface area (2700 m2/g) and highly mesoporous structures. Adsorption of small-sized TCE was stronger on the tire-rubber-based carbon and F400 resulting from the pore-filling effect. In contrast, due to the molecular sieving effect, their adsorption on HCH was lower. MWNT exhibited the lowest adsorption capacity toward HOCs because of its low surface area and characteristic of aggregating in aqueous solution. 相似文献
544.
通过测定两种气氛下(氮气和二氧化碳)的催化热解(HZSM-5为催化剂)的产率,并利用气质联用仪(GC/MS)分析热解油的成分,研究这两种热解气氛对快速催化热解生物质(玉米杆)的产率和液体产物的影响差异。结果表明:改变热解气氛对结果产生明显影响,CO2气氛对催化热解不利,该气氛下的固液气产率分别为30.30%,37.89%,31.81%,CO2促使快速催化热解的液体产量降低,促进水相产物的生成。对催化热解油的分析发现CO2气氛抑制了HZSM-5的去氧和芳香化催化作用,同时促进稠环芳烃的生成,使产物结构复杂化。 相似文献
545.
Hongwei Qin Liufang Chen Nan Lu Yahui Zhao Xing Yuan 《Frontiers of Environmental Science & Engineering in China》2012,6(1):107-116
In this article, the toxic effects of Enrofloxacin (ENFX) on Scenedesmus obliquus were studied, through investigating the growth, photosynthetic pigments, and protein contents. The possible toxic mechanisms
of ENFX were analyzed by determining the superoxide dismutase (SOD) activity, malondialdehyde (MDA) content, proline content,
and superoxide anion (O2−) generation rate. Results showed that the growth of algae was inhibited by ENFX and the 50% effective concentration (EC50) values for 24, 48, 72, and 96 h of ENFX were 88.39, 63.86, 45.10, and 59.16 mg·L−1, respectively. After treated with ENFX for 96 h, the contents of photosynthetic pigments decreased with the increase of ENFX
concentration, the content of soluble protein and the activity of SOD increased and then decreased, and the generation rate
of superoxide anion (O2−) increased continually. The contents of MDA and proline changed little in lower ENFX concentration groups, but increased
rapidly when treated with higher concentration groups. These results suggested that ENFX affected the growth of S. obliquus, and the main toxicity mechanism was that algal cells generated the reactive oxygen species under ENFX stress, and then the
reactive oxygen species (ROS) induced the oxidation damages of biologic macromolecules and changed the biomembrane permeability
further. 相似文献
546.
547.
长江上游长薄鳅生长和种群参数的估算 总被引:1,自引:0,他引:1
2010年9月~2012年8月在长江上游攀枝花等9个采样点收集到长薄鳅(Leptobotia elongata Bleeker)样本1 528尾,基于体长频率数据采用世界粮农组织(FAO)开发的FiSAT II软件研究了长江上游长薄鳅的生长与种群参数。估算结果显示长薄鳅的极限体长(L∞)为656.1mm,生长系数(k)为0.15/a,理论生长起点年龄(t0)为-0.048a。采用Pauly的经验公式估算长薄鳅的自然死亡系数(M)为0.33(其中长江上游年平均水温为18.4℃),总死亡系数(Z)、捕捞死亡系数(F)和开发率(E)分别为0.85、0.53和0.62。2010~2011年长江上游长薄鳅年均资源重量和资源数量分别为13.21t和162 862尾,最大可持续产量(MSY)为5.17t。经相关估算参数和相对单位补充渔获量分析得出,当前长江上游长薄鳅已处于过度捕捞状态,有必要采取有效保护措施。 相似文献
548.
Tan Yi Zhou Xue Peng Yutao Zheng Zijing Gao Xing Ma Yan Chen Shuo Cui Shihao Fan Beibei Chen Qing 《Environmental science and pollution research international》2022,29(28):42372-42383
Environmental Science and Pollution Research - Diverse phosphorus-containing materials (PCMs) were widely applied in remediation of cadmium-contaminated soils, and their effects on the change of... 相似文献
549.
River Channel Geometry and Rating Curve Estimation Using Height above the Nearest Drainage 总被引:1,自引:0,他引:1 下载免费PDF全文
Xing Zheng David G. Tarboton David R. Maidment Yan Y. Liu Paola Passalacqua 《Journal of the American Water Resources Association》2018,54(4):785-806
River channel geometry is an important input to hydraulic and hydrologic models. Traditional approaches to quantify river geometry have involved surveyed river cross sections, which cannot be extended to ungaged basins. In this paper, we describe a method for developing a synthetic rating curve to relate flow to water level in a stream reach based on reach‐averaged channel geometry properties developed using the Height above Nearest Drainage (HAND) method. HAND uses a digital elevation model (DEM) of the terrain and computes the elevation difference between each land surface cell and the stream bed cell to which it drains. Taking increments in water level in the stream, HAND defines the inundation zone and a water depth grid within this zone, and the channel characteristics are defined from this water depth grid. We apply our method to the Blanco River (Texas) and the Tar River (North Carolina) using 10‐m terrain data from the United States Geological Survey (USGS) 3D Elevation Program (3DEP) dataset. We evaluate the method's performance by comparing the reach‐average stage‐river geometry relationships and rating curves to those from calibrated Hydrologic Engineering Center's River Analysis System (HEC‐RAS) models and USGS gage observations. The results demonstrate that after some adjustment, the river geometry information and rating curves derived from HAND using national‐coverage datasets are comparable to those obtained from hydraulic models or gage measurements. We evaluate the inundation extent and show our approach is able to capture the majority of the Federal Emergency Management Agency (FEMA) 100‐year floodplain. 相似文献
550.
有机氯农药(Organochlorine Pesticides,OCPs)是一类由人工合成的杀虫广谱、毒性较低、残效期长的化学杀虫剂。本文以汕头市为研究区域,探讨了土壤OCPs的残留现状和特征,并对该区的土壤进行了环境质量评价和初步的生态风险评价。结果表明:(1)汕头地区土壤中OCPs的检出率高达99.13%,OCPs残留量的平均值是113.37 ng·g^-1,主要的OCPs污染物为DDTs和硫丹类;南澳县OCPs残留量平均值最高(174.68 ng·g^-1),其次为龙湖区,濠江区含量平均值最低(69.24 ng·g^-1);(2)与国内外一些地区土壤中OCPs的残留量对比,本研究区域土壤中的OCPs处于中等污染残留水平;与美国马里兰州标准、纽约州可容许的土壤浓度标准和我国的土壤环境质量标准相比较,OCPs基本没有超标;(3)本研究地区土壤存在较高的生态风险,OCPs可能对环境造成一定的危害,其中生态风险最高的是DDTs,BHCs的生态风险较低。 相似文献