Immobilization of lead by application of zeolite: Leaching column and rhizobox incubation studies

Application of zeolite can reduce lead (Pb) mobility in soil. Leaching columns and rhizobox incubation experiments were carried out to investigate the leaching processes and rhizosphere behavior of Pb in a Pb-contaminated soil amended with zeolite. Zeolite addition reduced Pb release from the contaminated soil as well as increasing leachate pH and decreasing the bioavailable Pb concentration. Leachate pH was not significantly different among different zeolite dose treatments at the same measurement time. Leaching of Pb from the treated soil was lower than that from the untreated soil for the first nine weeks but the trend was reversed for the final weeks of the study. The Pb concentration in the leachate did not appear to be sensitive to changes in pH. It was concluded that when a relatively low amount of zeolite was added (<20 mg kg(-1)), the cation exchange capacity was the dominant factor for regulating Pb leaching behavior. The DTPA extractable Pb in the rhizosphere was similar to 15% higher than that in the close-root and bulk soil. In addition, the amounts of DTPA extractable Pb in the rhizosphere soil not treated with zeolite were 10% and 16% higher than in the rhizosphere soil with 10 and 20 g kg-1 zeolite addition, respectively. It could be concluded that zeolite addition inhibits uptake of Pb by affecting rhizospheric behavior. (C) 2013 Elsevier B.V. All rights reserved.Application of zeolite can reduce lead (Pb) mobility in soil. Leaching columns and rhizobox incubation experiments were carried out to investigate the leaching processes and rhizosphere behavior of Pb in a Pb-contaminated soil amended with zeolite. Zeolite addition reduced Pb release from the contaminated soil as well as increasing leachate pH and decreasing the bioavailable Pb concentration. Leachate pH was not significantly different among different zeolite dose treatments at the same measurement time. Leaching of Pb from the treated soil was lower than that from the untreated soil for the first nine weeks but the trend was reversed for the final weeks of the study. The Pb concentration in the leachate did not appear to be sensitive to changes in pH. It was concluded that when a relatively low amount of zeolite was added (<20 mg kg(-1)), the cation exchange capacity was the dominant factor for regulating Pb leaching behavior. The DTPA extractable Pb in the rhizosphere was similar to 15% higher than that in the close-root and bulk soil. In addition, the amounts of DTPA extractable Pb in the rhizosphere soil not treated with zeolite were 10% and 16% higher than in the rhizosphere soil with 10 and 20 g kg-1 zeolite addition, respectively. It could be concluded that zeolite addition inhibits uptake of Pb by affecting rhizospheric behavior. (C) 2013 Elsevier B.V. All rights reserved

新疆伊犁盆地昭苏黄土剖面稀土元素特征/Characteristics of Rare Earth Elements in Loess Profiles in the Ili Basin, Xinjiang[J]

对晚更新世以来,伊犁地区与典型黄土高原地区黄土的稀土元素(REE)特征差异研究表明,伊犁盆地黄土剖面的REE特征不仅在含量上与典型黄土区的相似,分馏特征也基本相似,呈斜“L”型的分布模式,均发生轻、重稀土分异,分布曲线为负斜线,表现出中度的Eu负异常,Ce异常不明显,意味着晚更新世以来,不同地区黄土的物质来源具有一定的相似性.研究还发现,伊犁地区与黄土高原地区的稀土元素特征存在细微差异,昭苏黄土平均的稀土元素总量略高于昭苏古土壤平均值,与典型黄土区不同,这可能是由伊犁地区粉尘来源及其沉积环境的差异所致,且晚更新世以来不同区域黄土剖面REE特征参数三角图解也证实了这点

新疆伊犁河谷沙漠沉积的稀土元素特征及其环境意义/RARE EARTH ELEMENT CHARACTERISTICS OF DESERT SEDIMENTS IN ILI VALLEY AND THEIR ENVIRONMENTAL IMPLICATION[J]

以伊犁河谷西部塔克尔莫乎尔沙漠内的可克达拉(TKP)剖面作为研究对象开展了稀土元素特征分析,结合方解石变化特征,探讨沙漠沉积稀土元素与环境变化间的关系.研究结果表明TKP剖面的稀土元素总量(不含Y)平均为130.90 μg/g,变化范围为32.88 ～ 238.58μg/g,整个剖面分配模式相似,缓右倾斜型,轻稀土适度富集,δCe,δEu和LREE/HREE比值相近,Eu中度负异常,未见明显Ce异常,指示剖面物质来源的一致性和总体干旱、半干旱的气候环境.包括Ce在内的各稀土元素、∑REE以及LREE/HREE在垂向变化上高度相关,并与方解石含量存在较好的相关关系,表明其与气候变化密切相关,在干旱区的沙漠沉积中稀土元素对古气候变化具有良好的指示作用,并据此重建了晚全新世以来伊犁河谷的气候演变过程

中国西风区伊犁盆地塔勒德黄土-古土壤元素地球化学特征及环境意义/GEOCHEMICAL CHARACTERISTICS AND ENVIRONMENTAL SIGNIFICANCE OF THE TALEDE LOESS-PALEOSOL SEQUENCE IN WESTERLY AREA OF CHINA[J]

通过对新疆伊犁盆地塔勒德探井黄土-古土壤沉积物中常量、微量元素及其相关指标和参数的分析,讨论了西风区黄土-古土壤序列中各元素的分异规律及其与沉积环境之间的关系.结果表明塔勒德黄土-古土壤序列各层位中常量元素含量均表现出SiO2＞Al2O3 ＞CaO＞ Fe2O3 ＞MgO＞ Na2O＞K2O的变化特征；微量元素Rb,Sr,Sc,Ni,Cu,Ga,Mo,Y,Pb和Th在(弱)古土壤层、黄土层中相对下伏黄土L2层富集,而Zr,Cs,Nd和La在(弱)古土壤层中有不同程度的亏损.塔勒德黄土-古土壤的相关地球化学参数在整个研究地层序列中,黄土与古土壤之间分异并不显著,地球化学特征反映了受西风区影响的伊犁盆地黄土和古土壤形成时期其有效湿度较黄土高原同期小,形成环境更为干旱,具有其显著的区域特征.伊犁盆地黄土剖面元素地球化学特征主要受物质来源和气候环境的控制,当黄土物质具有相同来源时,其元素地球化学特征可以作为区域气候环境变化的良好代用指标

艾比湖周边灌丛沙堆风沙沉积记录的气候环境演化/Record for Climate Revolution in Aeolian Deposit of Nabkhas around the Ebinur Lake[J]

选择位于西风区的新疆艾比湖周边灌丛沙堆为研究对象,利用光释光测年初步建立风沙沉积的时间序列,分析了风沙沉积粒度和地球化学元素两个环境代用指标的古气候意义,并通过区域对比和综合分析,初步建立区域风沙气候环境演变序列.结果表明:研究区灌丛沙堆主要发育于晚全新世,缺失早中全新世的风沙沉积.晚冰期以来,艾比湖地区的风沙气候环境演变经历了一系列冷湿(凉湿)— 暖干(温干)的变化过程,其中暖干(温干)时期气候干旱,风力强劲,湖滨阶地主要发生风蚀过程,不利于灌丛沙堆的发育.晚全新世以来,艾比湖周边灌丛沙堆发育较普遍,风沙沉积至少记录了3次相对干旱期和3次相对湿润期.灌丛沙堆记录的风沙气候环境演化序列与北疆其他全新世沉积记录有较好的一致性,基本遵循晚次冰期以来气候变化的西风模式,同时也受到局地风沙地貌环境的影响