西辽河不同粒级沉积物对重金属铅的吸附—解吸特征研究

发布时间：2018-03-19 02:24

  本文选题：西辽河　切入点：沉积物　出处：《吉林农业大学》2015年硕士论文　论文类型：学位论文

【摘要】：重金属Pb的迁移转化是以泥沙颗粒为主要载体,河流输送主要以颗粒态铅为主。为估算随泥沙迁移的颗粒态Pb的质量分数与不同粒级沉积物吸附态铅对上覆水体的释放通量,采用吸附平衡法、解吸平衡法进行室内试验,进而为颗粒态铅的质量分数与吸附态铅的释放通量的估算提供理论依据。不同粒级沉积物对Pb的吸附特征均符合Langmuir吸附等温式。对重金属Pb的富集系数分别为黏粒为1.66、粉粒为1.48、细砂为0.85、粗砂为0.48。黏粒和粉粒的铅富集系数分别是粗砂的3.46和3.08倍,富集水平均为低度富集。粗砂和细砂级沉积物对重金属Pb没有富集作用。河流中细粒级沉积物中腐殖质含量要比粗粒级沉积物中腐殖质含量要高,稳结态腐殖质在细粒级的沉积物中所占的比例与其他粒级相比较则更明显。不同形态腐殖质含量对Pb的富集系数影响程度顺序为稳结态腐殖质(r为0.981)、紧结态腐殖质(r为0.951)、松结态腐殖质(r为0.832)。不同粒级沉积物对铅的富集系数与腐殖质总量呈显著正相关(p0.01),相关系数(r)为0.964;在西辽河汛期,重金属铅以黏粒级冲泻泥沙为载体随河水迁移其质量分数按照106.02 mg/kg估算,粉粒级可按98.71mg/kg估算。不同粒级沉积物对Pb的吸附特征均符合Langmuir吸附等温式。粗砂、细砂、粉粒、黏粒铅解吸比例(Dr)依次为:28.85%、15%、0.68%、0.65%;其解吸迟滞性指数(TⅡ)依次为:0.08、0.34、0.53、0.59。粗砂粒级,解吸比例(Dr),明显高于细粒级,而解吸迟滞性指数(TⅡ),明显低于其他粒级;西辽河不同粒级沉积物吸附态铅的释放通量为粗砂为22.42mg/kg、细砂为11.83mg/kg、粉粒为0.61mg/kg、黏粒为0.67mg/kg。尽管粗砂粒级对于铅的吸附量较低(77.31mg/kg),但粗砂粒级对于铅的解吸比例较高(28.85%)。致使粗砂粒级吸附态铅的释放通量较大(22.30mg/kg)。吸附在黏粒与粉粒两个粒度的重金属铅是地球化学循环过程中不可或缺的一部分。
[Abstract]:In order to estimate the mass fraction of particulate Pb and the flux of adsorbed lead to overlying water, the transport of heavy metal Pb is mainly carried by sediment particles. The adsorption equilibrium method and desorption equilibrium method were used for laboratory test. It provides theoretical basis for the estimation of mass fraction of granular lead and flux of adsorbed lead. The adsorption characteristics of Pb in different granular sediments are in accordance with the Langmuir adsorption isotherm. The enrichment coefficient of Pb for heavy metal is viscosity, respectively. The lead enrichment coefficients of clay and silt are 3.46 and 3.08 times of coarse sand, respectively, and 1.66 of silt, 0.85 of fine sand, 0.48 of coarse sand, 1.66 of silt, 0.85 of fine sand and 0.48 of coarse sand, respectively. The enrichment level was low. Coarse sand and fine sand sediment had no enrichment effect on heavy metal Pb. The humus content in fine grain sediment in river was higher than that in coarse grain sediment, and the content of humus in fine grain sediment was higher than that in coarse grain sediment, and the content of humus in fine grain sediment was higher than that in coarse grain sediment. The proportion of stable humus in fine-grained sediment was more obvious than that in other grain-grade sediments. The order of influence of different humus content on Pb enrichment coefficient was as follows: stable humus content r = 0.981g, compact humus content = 0.981g. The content of lead in different grain sediments was positively correlated with the total amount of humus, and the correlation coefficient (r) was 0.964.In the flood season of West Liaohe River, there was a significant positive correlation between the enrichment coefficient of lead and the total amount of humus, and the correlation coefficient (r) was 0.964.In the flood season of the West Liaohe River, there was a significant positive correlation between the enrichment coefficient of lead and the total amount of humus. The mass fraction of heavy metal lead is estimated according to 106.02 mg/kg and 98.71 mg / kg with the transport of clay grade sediment. The adsorption characteristics of Pb on different grained sediments are in accordance with the Langmuir adsorption isotherm, coarse sand, fine sand, silt, fine sand, silt, fine sand, silt, coarse sand, fine sand, silt, fine sand, fine sand and silt, The viscosity lead desorption ratio (Dr) was: 1: 28.85 / 150.68 and 0.65, respectively; the desorption hysteresis index (TII) was 0. 088 / 0.34 + 0. 53- 0. 59.The desorption ratio of coarse sand was significantly higher than that of fine grain, while the desorption hysteresis index (T 鈪，

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