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841.
Adsorption-desorption behavior of acetochlor to soils in the presence of some environmental substances 总被引:5,自引:0,他引:5
IntroductionAlthoughtheherbicideacetochlor [2 chloro N (ethoxymethyl) N (2 ethyl 6 methylphenyl)acetamide]hasbeenusedfortenyearsinChina,limitedinformationhasbeencollectedtodetermineitsfateandtransportintheenvironment.Formulationsaregenerallysoldasemulsifiabl… 相似文献
842.
Assessment of labile phosphorus fractions and adsorption characteristics in relation to soil properties of West African savanna soils 总被引:2,自引:0,他引:2
O. C. Nwoke B. Vanlauwe J. Diels N. Sanginga O. Osonubi R. Merckx 《Agriculture, ecosystems & environment》2003,100(2-3):285
A large proportion of total P in the soils of the area is unavailable to plants and consequently P is the second most limiting nutrient. The labile and moderately labile phosphorus fractions and adsorption characteristics of surface and subsurface horizons of eleven soil profiles in the derived savanna (DS) and the northern Guinea savanna (NGS) of West Africa were assessed. The labile P fractions are the resin and HCO3-extractable inorganic (Pi) and organic (Po) P. The moderately labile fractions are the NaOH-extractable portion of soil P in the Hedley sequential procedure. In the DS soils, the resin P, considered the most readily available fraction, varied from 1 to 14 mg kg−1, HCO3-Pi ranged from 3.3 to 11, and HCO3-PO was between 4 and 12 mg kg−1 in the surface horizon. In the NGS, the topsoil contained 1.5–3 mg kg−1 of resin P, 5–8 mg kg−1 of HCO3-Pi, and 7.5–9.7 mg kg−1 of HCO3-Po. Sodium hydroxide-Po was the largest of the fractions in all the soils studied. It ranged from 23 to 55 mg kg−1 in the topsoil. In general, the labile P levels were higher in soils of the DS than of the NGS and were related to the oxalate-extractable Fe (Feox), and Al (Alox) as well as to soil texture. The subsoil of Kasuwan Magani (profile KS 9–21 cm) required 153 mg P kg−1 to maintain 0.2 mg P l−1 in solution (standard P requirement), and Danayamaka (profile DD 7–32 cm) required 145 mg P kg−1. These could translate to 214 and 200 kg P ha−1 if a plow layer of 10 cm is assumed. Because these are within the plow layer, more P fertilizer would be needed for crop production than in the other soils. The standard P requirement and the adsorption maxima were related to Feox and Alox, dithionite-Fe (Fed), and texture. The increase in labile P content with decreasing Feox and Alox could imply that management practices capable of reducing the activities of Fe and Al in solution might improve P availability. 相似文献
843.
IntroductionChromium ,whichistoxictomanandotherlivingorganisms,presentspotentiallyseriousenvironmentalproblemsthroughouttheworld .ChromiummainlyexistsintwoformsasCrⅢ andCrⅥ .CrⅢisoflesspoisonousness,butCrⅥ exhibitsastrongtoxicity .WhenCrⅥisdischargedintowa… 相似文献
844.
845.
天然水颗粒电动电位的化学模型 总被引:1,自引:0,他引:1
结合表面络合化学和双电层物理理论建立天然水颗粒电动电位(即ζ电位)与颐粒表面固有的化学性质及天然水化学条件之间的定量关系。在不同化学条件下,对均匀胶体颗粒(包括聚苯乙烯Latex颗粒和α-Fe_2O_3颗粒)进行电泳测定来验证该模型。结果表明,颗粒表面ζ电位与颗粒表面离子化官能团(—COOH或—OH)的化学性质、天然水pH值和专属吸附的阴阳离子(Ca~(2+)和PO_4~(3-))有密切关系。 相似文献
846.
In this work,hydrothermal technique combined with KOH activation were employed to develop a series of porous carbons (NPCK-x) using tobacco stem as a low-cost carbon source and (NH4)2C2O4 as a novel nitrogen-doping agent.Physicochemical properties of NPCK-x were characterized by Brunauer-Emmett-Teller,field emission scanning electron microscopy,X-ray diffraction,Raman microscope,elemental analysis,and X-ray photoelectron spectroscopy.Results showed tha... 相似文献
848.
研究了XDA-200大孔树脂对水溶液中邻苯二甲酸的吸附。结果表明XDA-200树脂对水溶液中的邻苯二甲酸吸附速度很快,30min内基本达到平衡,其后达到完全平衡的吸附进程非常缓慢。树脂对邻苯二甲酸的吸附量随质量浓度增加而增加。pH值降低,有利于邻苯二甲酸在溶液中以分子态存在,易于树脂吸附。邻苯二甲酸的吸附均满足Freundlich和Langmiur等温吸附方程。泄漏点与进水浓度和流速均有很大关系。 相似文献
849.
850.
米菲司酮废水处理的试验探索 总被引:1,自引:0,他引:1
对米菲司酮生产中产生的高浓度有机废水(CODcr8.8×10^4mg/L),采用常压蒸馏-活性炭吸附方法进行试验性处理,CODcr的去除率可达95%以上,CN-去除率达99.9%,并可回收乙醇等低沸点有机溶剂。 相似文献