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991.
992.
2,3,7,8,-四氯苯噁英对NIH小鼠早期妊娠和生殖激素的影响 总被引:1,自引:0,他引:1
用不同剂量的2,3,7,8 四氯苯二英(2,3,7,8 tetrachlorodibenzopdioxin,TCDD)对小鼠胚胎附植数量和生长发育情况进行剂量反应评估,分析TCDD对假孕小鼠子宫蜕膜生长状况的影响以及比较胚胎种植前后染毒效果.所有样本采集血液,测定母体血清雌二醇和孕酮的浓度变化.结果表明,50和100ng·(kg·d)-1TCDD处理的孕鼠,胚胎附植数量明显减少(P<0 05),着床后胚胎出现发育迟缓,质量减轻(P<0 05);同等剂量TCDD处理的假孕小鼠,子宫蜕膜生长受到了极显著的抑制(P<0 01);种植前后染毒效果比较发现种植前期染毒的小鼠胚胎对TCDD更为敏感.母体血清雌二醇浓度随剂量和染毒时段有不同程度的升高,而孕酮浓度则极显著下降(P<0 01).由此表明低剂量TCDD可能通过对生殖激素的干扰,强烈影响NIH小鼠妊娠早期生殖生理状态和着床后胚胎的发育.实验同时证明小鼠也可作为早期妊娠毒物研究的供试动物,用以筛选动物和人类早期妊娠的有害化合物. 相似文献
993.
994.
Photodegradation of nitroaromatic compounds in aqueous solutions in the UV/H2O2 process 总被引:1,自引:1,他引:0
Photodegradation of nitrobenzene and nitrophenols in aqueous solutions by means of UV/H2 O2 process was studied in the Rayox batch reactors. Three nitrophenol isomers were identified as main photoproducts in the irradiated NB aqueous solutions. The distribution of nitrophenol isomers follows the order p-〉 m-〉 o-nitrophenol. Other intermediates detected include nitrohydroquinone, nitrocatechol, catechol, benzoquinone, phenol, nitrate/nitrite ions, formic acid, glyoxylic acid, maleic acid, oxalic acid and some aliphatic ketones and aldehydes. The degradation of nitrobenzene and nitrophenols at initial stages follows the first-order kinetics and the decay rate constants for nitrobenzene(NB) are around l0^-3-10^-2 s^-1 and for nitrophenols are around 10^-2 s^-1. The decomposition of H2 O2 in the presence of NB and each nitrophenol isomers follows zero-order kinetics. The quantum yields at initial stages for NB decay were estimated around 0.30 to 0.36, and for NPs decay is around 0.31-0.54. 相似文献
995.
洛阳市空气微生物污染初步调查 总被引:2,自引:0,他引:2
采用平皿沉降法对洛阳市空气微生物浓度进行了初步测定。结果表明:空气细菌、真菌和总菌的浓度分别为7448CFU/m^3、782CFU/m^3和9063CFU/m^3,真菌与总菌的浓度比值为8.64%,空气质量处于微污染水平;空气微牛物浓度空间差异显著,可分为中度污染、轻度污染、微污染和较清洁4个等级;从功能区划看,商业交通混合区污染最重,生活区和工业区空气质量最好;空气污染微生物主要为G^+球菌和交链孢,其次还有少量芽孢杆菌和青霉、曲霉、毛霉等。 相似文献
996.
997.
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Recycling of electrolytic manganese solid waste in autoclaved bricks preparation in China 总被引:1,自引:0,他引:1
China has played a dominant role in global electrolytic manganese metal (EMM) production, accounting for over 98 % of the total world capacity since 2008. However, with the rapid development of the EMM industry and depletion of mineral ores, electrolytic manganese solid waste (EMSW) is piling up, so more large-scale landfills are needed. The environmental problems generated by EMSW pose severe threats to soil and ground water, and have become the hot issues in society. The aim is to consume and recycle EMSW, and the primary route is to make autoclaved bricks. However, less attention has been given to the procedure and strength-forming mechanism of EMSW bricks, not to mention the production line of the brick. On the basis of physical and chemical property analysis, the pretreatment process of EMSW was indispensable to solidify/stabilize the heavy metals, such as Mn, Zn, Cd, Pb, etc.. This paper expatiated on the procedure of making EMSW autoclaved bricks, analyzed in detail the strength formed by different cementitious materials with cement properties, and introduced the practical engineering of EMSW autoclaved bricks. The results showed that the pretreatment process with quicklime was effective in solidifying/stabilizing the heavy metals. The compressive strength of EMSW bricks reached 10.05 MPa when quicklime 9 % (w/w) added. Cement may be an ideal cementitious material to create EMSW bricks of high strength in experiments and on the production line. Quicklime and cement used simultaneously produced a lower strength than that when adding cement alone because the gypsum from EMSW and an alkali could generate deleterious effects, e.g., expansion or burst. In the production line of EMSW bricks, an appropriate mix proportion to make high-quality autoclaved bricks was determined: EMSW 30–40 %, cement 10–20 %, and aggregates 40–60 %. The low content of heavy metals tested by toxicity leaching may deduce that the EMSW autoclaved bricks have low environmental risk. However, long-term environmental risk evaluation will be needed, requiring more tests and leaching modeling. Employing EMSW to make high-quality autoclaved bricks may be a promising waste-to-resource strategy. 相似文献
1000.
采用移动床生物膜反应器(MBBR)处理配制模拟废水,实验结果表明,水力停留时间为6h、悬浮填料填充率为40%时,在不同C/N/P比率条件下,MBBR对COD、NH4+-N和TN去除性能好且稳定,平均去除率分别达到90%、94.8%和62.39%以上,而TP的去除率受C/N/P值影响较大,当C/N/P的比值为100/10/1.8时,平均去除率达到58.03%。一定的溶解氧(DO)质量浓度能保证反应器中COD、NH4-N高效稳定的去除,同时是TN和TP同时去除的重要影响因素,在MBBR中最佳DO值约为3mg/L。由于附着在悬浮填料生物膜内部存在厌氧、缺氧微环境条件,在反应器中存在少量的反硝化聚磷菌。 相似文献