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461.
Acute toxicity and presumable harmless concentration of two commercial insecticides, Furadan 3G and Malataf 50E were reported for tubificid worms, Tubifex tubifex and Limnodrilus hoffmeisteri. L. hoffmeisteri were found more susceptible to both the insecticides; the Furadan was found to be more toxic than Malataf to tubificid worms. Analysis of variants showed a significant difference between safe concentrations of the same insecticide to different species. 相似文献
462.
The present study performed a roadside data analysis to provide baseline data for exploring associations between environmental exposure to four gaseous pollutants and health effects on residents living near roadways. The yearly roadside concentrations of CO and SO2 showed a well-defined decreasing trend, whereas those of NO2 and O3 exhibited the reverse trend. In most cases, the diurnal trends of the roadside concentrations were well-defined for all seasons, plus the daytime concentrations were higher than the nighttime concentrations. In contrast to the other target pollutants, the daytime O3 concentrations observed at the roadside sites were lower than those observed at the residential site, likely due to high-levels of fresh NO from traffic emissions that rapidly react with O3, thereby reducing the O3 roadside level. The Sunday roadside concentrations of CO, NO2, and SO2 were similar to or somewhat lower than the weekday concentrations. Conversely, for O3, the Sunday roadside concentrations were similar to or somewhat higher than the weekday concentrations. The higher O3 concentrations on Sunday may be due to the reduced titration from a decrease in NOx emissions under VOC-limited conditions (low VOC/NOx conditions). The monthly averages of O3 concentrations exhibited the reverse seasonal variation to the other target compounds, with peak O3 concentrations between April and June, and the second peak between August and October. It is also suggested that for O3, the 8-h standard is more stringent than the 1-h standard, while for NO2 and SO2, the 1-h standard is more stringent than the 24-h standard. The multiple regression equations obtained from the relationship between the concentrations and five meteorological parameters indicated that the number and type of meteorological variables in the equations varied according to the pollutant, monitoring station, or season. 相似文献
463.
采用体元技术建立滑坡体真三维模型,通过基本三棱柱体构建具有复杂曲面结构的空间组合体,每个单元都赋予不同的属性,为滑坡体三维稳定性分析提供基本的前、后处理功能.以此为基础,并结合三维极限平衡分析计算方法,开发了相关的滑坡三维模拟与稳定性分析软件,并成功应用于清江库岸大型滑坡的三维仿真计算. 相似文献
464.
臭氧-生物活性炭组合工艺中最佳臭氧投加剂量的确定 总被引:10,自引:1,他引:9
在水处理过程中投加臭氧,可提高饮用水的可生物降解性.臭氧氧化后继的生物过滤,可以减少水中可生物降解有机物数量,提高饮用水的生物稳定性.试验表明,臭氧投加量2~8mg/L可使AOC-P17,AOC-NOX和BDOC分别增加20.9%~85.5%,42.1%~158.2%和21.4%~84.4%.臭氧投加量为3mg/L时,AOC和BDOC增加得最多,即3mg/L的臭氧投量为最佳投加剂量.生物活性炭滤柱(BAC)出水AOC浓度(乙酸碳)均低于50μg/L,在35.9~46.6μg/L之间,属于生物稳定性水质. 相似文献
465.
The effect of hexadecyltrimethyleamine bromide (HDTMAB) on the removal of A lexandrium sp. LC3 under cupric glutamate stress was investigated. Toxic effect of cupric glutamate on A lexandrium sp. LC3 was significantly promoted in the presence of HDTMAB, especially at 3.0 cmc of HDTMAB. It was found that the sulfhydryl group content of the cell decreased, while the malonaldehyde content and membrane permeability increased when A lexandrium sp. LC3 was treated with HDTMAB and cupric glutamate complex, compared with cupric glutamate alone. The data suggest that HDTMAB might stimulate the damage of A lexandrium sp. LC3 by enhancing the membrane permeability. 相似文献
466.
金属氧化物纳米颗粒的广泛应用导致它们大量地释放到水环境中,其独特的理化性质有可能改变水环境中其他共存污染物(如重金属)的生态毒性。为评价沉积物中纳米氧化铝(Al2O3-NPs)对重金属Cd生态毒性的影响,采用底栖生物慢性暴露研究了Al2O3-NPs存在条件下Cd在底栖动物铜锈环棱螺体内生物积累的变化和Cd对肝胰脏抗氧化防御系统关键成分超氧化物歧化酶(SOD)与脂质过氧化指标丙二醛(MDA)以及Ⅱ相反应的关键酶谷胱甘肽-S-转移酶(GST)的影响。结果表明,低Cd浓度(5μg·g-1)时,Al2O3-NPs对Cd生物积累没有影响;中、高Cd浓度(25、100μg·g-1)时,Al2O3-NPs显著促进Cd的生物积累,Al2O3-NPs对Cd的生物转运具有明显的携带效应。低Cd浓度时,无Al2O3-NPs处理组和Al2O3-NPs处理组的SOD活性与对照组相比均没有显著差异;中Cd浓度时,SOD活性显著升高,而高Cd浓度时,SOD活性显著下降,而且Al2O3-NPs处理组的SOD活性显著低于无Al2O3-NPs处理组,Al2O3-NPs的存在加重了Cd对肝胰脏细胞的氧化胁迫或损伤。高Cd浓度时,无Al2O3-NPs处理组和Al2O3-NPs处理组的MDA水平均显著升高,但Al2O3-NPs处理组的MDA水平显著低于无Al2O3-NPs处理组,进一步证明Al2O3-NPs对Cd氧化损伤的增强作用。中、高Cd浓度时,无Al2O3-NPs处理组和Al2O3-NPs处理组的GST活性均显著下降,但Al2O3-NPs处理组的GST活性均显著低于无Al2O3-NPs处理组,同样说明了Al2O3-NPs对Cd毒性的增强作用。本研究提供了在沉积物-底栖动物体系中Al2O3-NPs促进重金属生物积累的证据,而且Cd毒性的变化与肝胰脏中Cd的生物积累水平的变化基本一致,在中、高Cd浓度下,由于Al2O3-NPs的存在显著促进了Cd的生物积累,因而增强了Cd对铜锈环棱螺的生态毒性。 相似文献
467.
Al2O3为载体的催化剂净化贫燃汽车尾气研究 总被引:2,自引:0,他引:2
在富氧条件下,考察了C3H6和C2H5OH在Ag/Al2O3、In/Al2O3、Sn/Al2O3、Co/Al2O3、Pt/Al2O3和Ag/Al2O3+Pt/Al2O3组合催化剂上选择性还原NO的性能.结果表明,Ag/Al2O3具有最高的NO还原活性.在负载型过渡金属氧化物催化剂上,会生成显著量的CO,其HC和CO氧化转化温度也远远高于Pt/Al2O3催化剂.串联组合Ag/Al2O3+Pt/Al2O3催化剂可显著拓宽活性温度范围,促进HC和CO氧化,降低N2O和CH3CHO生成量. 相似文献
468.
吊水壶尾矿坝渗流特性三维有限元分析 总被引:2,自引:1,他引:1
本文结合工程实例,以吊水壶尾矿坝为背景,建立现状尾矿坝三维模型,利用三维有限元法反演分析现状尾矿坝的渗流场,将计算结果与勘察的浸润面对比分析,验证模型的可靠性和合理性。基于此模型建立加高后的尾矿坝三维模型,计算正常蓄水位和设计洪水位两种工况下的渗流场,分析坝体浸润面埋深、滩长、渗流坡降等,结果表明,不设排渗措施时,尾矿坝干滩长度、浸润面埋深均能满足规范要求,而且尖流性态良好,满足渗透稳定。提出该尾矿坎可通过加高工程来进行渗流控制的建议。 相似文献
469.
Dian Ding Jia Xing Shuxiao Wang Xing Chang Jiming Hao 《Frontiers of Environmental Science & Engineering》2019,13(5):76
470.
Minimizing opportunity costs to aquatic connectivity restoration while controlling an invasive species 下载免费PDF全文
Austin W. Milt Matthew W. Diebel Patrick J. Doran Michael C. Ferris Matthew Herbert Mary L. Khoury Allison T. Moody Thomas M. Neeson Jared Ross Ted Treska Jesse R. O'Hanley Lisa Walter Steven R. Wangen Eugene Yacobson Peter B. McIntyre 《Conservation biology》2018,32(4):894-904
Controlling invasive species is critical for conservation but can have unintended consequences for native species and divert resources away from other efforts. This dilemma occurs on a grand scale in the North American Great Lakes, where dams and culverts block tributary access to habitat of desirable fish species and are a lynchpin of long‐standing efforts to limit ecological damage inflicted by the invasive, parasitic sea lamprey (Petromyzon marinus). Habitat restoration and sea‐lamprey control create conflicting goals for managing aging infrastructure. We used optimization to minimize opportunity costs of habitat gains for 37 desirable migratory fishes that arose from restricting sea lamprey access (0–25% increase) when selecting barriers for removal under a limited budget (US$1–105 million). Imposing limits on sea lamprey habitat reduced gains in tributary access for desirable species by 15–50% relative to an unconstrained scenario. Additional investment to offset the effect of limiting sea‐lamprey access resulted in high opportunity costs for 30 of 37 species (e.g., an additional US$20–80 million for lake sturgeon [Acipenser fulvescens]) and often required ≥5% increase in sea‐lamprey access to identify barrier‐removal solutions adhering to the budget and limiting access. Narrowly distributed species exhibited the highest opportunity costs but benefited more at less cost when small increases in sea‐lamprey access were allowed. Our results illustrate the value of optimization in limiting opportunity costs when balancing invasion control against restoration benefits for diverse desirable species. Such trade‐off analyses are essential to the restoration of connectivity within fragmented rivers without unleashing invaders. 相似文献