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671.
毒死蜱对六种淡水节肢动物的毒性与风险评价 总被引:2,自引:0,他引:2
采用静态法测定了毒死蜱对六种水生节肢动物的48 h毒性.试验结果表明,按实测浓度计,毒死蜱对大型溞Daphnia magna、老年低额溞Simocephalus vetulus、多刺裸腹潘Moina macrocopa、锯缘真蚤Eucyclops serrulatus、介形虫Pseudocandona sp.、花翅摇蚊Chironomus kiiensis幼虫的48 h-LC50(单位:μg· L-1)分别为0.523、0.0528、0.178、7.32、2.75、90.3.这表明毒死蜱对于上述6种水生节肢动物均属于剧毒.将稻田施药下的环境浓度预测值(EECs)与基于实测浓度的48 h-LC50相比对,得到毒死蜱相对于6种水生节肢动物的急性风险商值(RQ)分别为10.29、52.95、27.20、0.73、1.96、0.06.这说明除了摇蚊幼虫,按推荐剂量使用的毒死蜱对于其他5种水生节肢动物有较高程度的急性风险. 相似文献
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研究了CuCl2在荷结构负电荷皂土上的吸附性能,考察了pH、无机以及有机添加剂等因素的影响,并结合IR和XRD实验结果探讨了吸附机理。研究表明,皂土对CuCl2有很强的吸附能力,其吸附动力学和吸附等温线分别符合准二级速率方程和Langmuir方程。初始pH增大,吸附量增加。无机以及有机添加剂均能能明显抑制吸附。Cu2+在皂土上的吸附层在微观上可分为因化学键合作用而形成的内络合层和因静电作用而形成的外络合层。 相似文献
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研究了Cr(Ⅵ)在带结构正电荷的Mg-Al型类水滑石(HTlc)上的脱附性质,考察了多种脱附剂的脱附性能,研究了脱附剂种类、浓度、pH值和脱附时间等因素的影响。实验表明,脱附平衡时间比吸附平衡时间稍长,不同的脱附剂脱附效果不一样,对同一种脱附剂来说,随着脱附剂浓度的增大,脱附量增大;随着pH值的升高,脱附量总体呈上升趋势。 相似文献
676.
Hansen V Roos P Aldahan A Hou X Possnert G 《Journal of environmental radioactivity》2011,102(12):1096-1104
Natural organic matter, such as humic and fulvic acids and humin, plays a key role in determining the fate and mobility of radioiodine in soil and sediments. The radioisotope 129I is continuously produced and released from nuclear fuel reprocessing plants, and as a biophilic element, its environmental mobility is strongly linked to organic matter.Due to its long half-life (15.7 million years), 129I builds up in the environment and can be traced since the beginning of the nuclear era in reservoirs such as soils and marine sediments. Nevertheless, partition of the isotope between the different types of organic matter in soil and sediment is rarely explored. Here we present a sequential extraction of 129I and 127I chemical forms encountered in a Danish soil, a soil reference material (IAEA-375), an anoxic marine sediment from Southern Norway and an oxic sediment from the Barents Sea. The different forms of iodine are related to water soluble, exchangeable, carbonates, oxides as well as iodine bound to humic acid, fulvic acid and to humin and minerals. This is the first study to identify 129I in humic and fulvic acid and humin. The results show that 30-56% of the total 127I and 42-60% of the total 129I are associated with organic matter in soil and sediment samples. At a soil/sediment pH below 5.0-5.5, 127I and 129I in the organic fraction associate primarily with the humic acid while at soil/sediment pH > 6 129I was mostly found to be bound to fulvic acid. Anoxic conditions seem to increase the mobility and availability of iodine compared to oxic, while subaerial conditions (soils) reduces the availability of water soluble fraction compared to subaqueous (marine) conditions. 相似文献
677.
Capability of novel ZnFe₂O₄ nanotube arrays for visible-light induced degradation of 4-chlorophenol 总被引:1,自引:0,他引:1
Highly ordered ZnFe2O4 nanotube arrays were successfully prepared by anodic aluminum oxide templates from sol-gel solution. The results from environmental scanning electron microscopy and X-ray photoemission spectroscopy indicated that the as-prepared samples were vertically aligned spinel ZnFe2O4 nanotube arrays, and the nanotubes were uniform along the axial direction with an average diameter of approximately 200 nm. The absorption edge of ZnFe2O4 nanotube arrays shifted to a higher energy in the UV-Vis absorption spectrum compared with that of ZnFe2O4 nanoparticles film. The synthesized ZnFe2O4 nanotube arrays exhibited excellent photocatalytic capability for degradation of 4-chlorophenol under visible-light irradiation. The main intermediate degradation species of 4-chlorophenol identified by liquid chromatography-mass technique were benzoquinone, hydroquinone, hydroxybenzoquinone and 2-peroxy-o-dihydroxybenzene. The degradation pathways of 4-chlorophenol under visible-light irradiation was derived and discussed by interpreting the observations of the intermediate species in the photocatalytic reactions. 相似文献
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