不同来源土样胶体对氯霉素吸附行为的影响

Effects of different soil colloids on the sorption behavior of chloramphenicol

选取不同来源沉积物或土壤样品(沉积物A1和A2,天然土壤B1和B2,市售营养土B3),采用切向超滤与多种纳米分析技术相结合的方法,分析了不同土样中胶体的理化特征及其对氯霉素(CAP)吸附行为的影响.荧光区域积分法结果显示,土样胶体的荧光组分以色氨酸类蛋白质、类富里酸和类腐殖酸为主,络氨酸类蛋白质和溶解性微生物代谢物质存在较少.吸附实验结果表明,B3胶体对CAP的吸附率最大(36.25%),在胶体浓缩液和超滤液中的分配比例最高(1.91),但其有机碳归一化结合系数最低(3.93).与天然土壤相比,河湖沉积物胶体的吸附率较高,但其与CAP的结合能力却较低.冗余分析结果表明,胶体对CAP的吸附主要与其芳香度、有色溶解性有机质丰度、溶解性有机碳浓度及分子量有关;此外,胶体的腐殖化程度、芳环上羧基、羰基等官能团的比重及荧光物质中溶解性微生物代谢产物和类腐殖酸对CAP的吸附行为也具有较大影响.

In this study,soil/sediment samples from five different sources(including sediment samples A1 and A2,soil samples B1 and B2,and nutrient soil B3)were selected to characterize the physicochemical properties of the soil colloids and to investigate their impact on the sorption behavior of chloramphenicol(CAP).To achieve this purpose,the cross-flow ultrafiltration was used combined with a multi-method analytical approach.The results of fluorescence regional integration showed that tryptophan⁃like protein,fulvic acid⁃like and humic acid⁃like were the main fluorescence components in these soil colloids.B3 colloids showed the maximum sorption rate(36.25%),the highest distribution rate between retentates and permeates(1.91),and the lowest value of the organic carbon-normalized partition coefficient(logKDOC)for CAP(3.93).Compared with the colloids from natural soils,the relative higher sorption rate and lower value of logKDOC were found for the colloids from sediments.The redundancy analysis showed that the sorption of CAP onto the soil colloids was mainly attributed to its aromaticity,the abundance of chromophoric dissolved organic matter,the concentration of dissolved organic carbon and molecular weight.Besides,the humification degree of colloid and the proportion of carboxyl,carbonyl and other functional groups on the aromatic ring,and microbial⁃like and humic acid⁃like in fluorescent components also had a great impact on the sorption behavior of CAP.