共查询到18条相似文献，搜索用时 125 毫秒
1.
为揭示冲积与湖积成因土壤镉的吸附特征,以安徽省当涂县冲积成因的江心洲和冲积、湖积成因的大陇乡根际土壤为研究对象,开展土壤镉的等温吸附实验和吸附动力学实验.等温吸附实验结果表明,冲积土壤镉的吸附量（S）、等温吸附常数（K）和固液分配系数（Kd）均较湖积土壤明显偏大,显示冲积土壤对镉的吸附能力较湖积土壤强;吸附动力学实验表明,冲积土壤的最大吸附量、平衡吸附量均较湖积土壤大,吸附速率也明显偏大,尤其在吸附实验早期更为显著;等温吸附常数K和平衡吸附速率Vb与土壤理化性质的分析表明,土壤pH是造成研究区土壤镉吸附能力差异的主要原因,其次为物理性粘粒含量;土壤pH是影响研究区冲积土壤镉吸附能力的主要因素;湖积土壤镉的吸附能力受土壤pH、有机质含量、Cd含量、物理性粘粒含量等因素的综合影响.研究对于揭示Cd在水土系统的迁移转化规律以及土壤Cd的污染防治具有重要的指导意义. 相似文献
2.
通过静态吸附实验,研究了兰州地区黄土对含油废水中石油类污染物的吸附作用,并对温度、pH、土壤粒径、有机质含量和含盐量等影响吸附作用的因素进行了分析。实验结果表明:该类型黄土对可溶性石油饱和溶液的吸附等温线符合Langmuir吸附模式,其吸附能力随温度、pH的升高而降低;吸附量随土壤粒径的减小呈增大趋势;吸附量与土壤有机质含量、含盐量呈线性关系,随着有机质含量、含盐量的增高吸附量增大。 相似文献
3.
重金属离子在胡敏酸-高岭石复合体上的吸附 总被引：6，自引：0，他引：6
本文研究了胡敏酸存在下高岭石对重金属离子的吸附行为。实验结果表明:①胡敏酸和Cu2 溶液按先后顺序或同时加入高岭石中反应,在Cu2 平衡浓度<10mg/L时,3种加入顺序对Cu2 的吸附量基本相同,当Cu2 平衡浓度>10mg/L时,(K Cu) HA和(K Cu HA)两种加入顺序对Cu2 的吸附量比(K HA) Cu的略大。②在pH=5时,胡敏酸-高岭石复合体对Cu2 的吸附量明显大于纯高岭石。这是由于胡敏酸含有大量的羧基和酚羟基等活性基团,吸附在高岭石上的胡敏酸增加了其表面吸附位,在复合体表面形成了S—HA—Cu三元配合物,且Cu2 的吸附量与复合体中胡敏酸的含量在一定范围内成正相关;③溶液pH值在4～7之间变化可调控复合体对Cu2 的吸附机制。④在Cu2 和Cd2 共存时,随着金属离子初始浓度的增大,Cu2 的吸附量呈直线上升,而Cd2 的吸附量增加缓慢,表明复合体对Cu2 的吸附能力比对Cd2 强。 相似文献
4.
阿拉尔河下游沉积物对铀的吸附及其影响因素 总被引：2，自引：0，他引：2
采用静态吸附实验,研究了阿拉尔河下游沉积物对水溶液中铀的吸附机制,分析了反应时间、pH值、粒径、固液比、铀初始浓度等因素对沉积物吸附铀的影响,并对其吸附动力学过程和热力学性质进行了探究。结果表明:阿拉尔河河流沉积物对铀的吸附在16 h左右趋于平衡;溶液pH值对沉积物吸附铀具有显著影响,当pH=6~7时,吸附率最大;在一定条件下,吸附率与固液比呈正相关,与粒径及铀初始浓度呈负相关;吸附量与固液比呈负相关,与铀初始浓度呈正相关;吸附动力学过程遵循准二级动力学模型,由两个以上步骤共同控制;吸附热力学符合Freundlich吸附等温模型,沉积物对铀的吸附以多分子层吸附为主,是自发、吸热的熵增过程。 相似文献
5.
南宁市郊周边农田土壤-农作物系统重金属元素迁移特征及其影响因素 总被引：3，自引：0，他引：3
通过采集南宁市郊农田中玉米、蔬菜、水稻可食部分及其根系土150组,研究重金属元素在不同土壤-农作物系统中迁移特征及其影响因素,结果表明:根系土中Hg、Cd、Cr、Cu、Ni、Pb、Zn平均含量分别为0.116、0.202、56.76、22.12、14.49、25.18和56.28 mg·kg-1。农作物对应平均含量分别为0.001 1、0.037、0.054、1.153、0.205、0.011和9.37 mg·kg-1。根系土富集因子表明Cd受到不同程度人为活动影响,Cr和Ni主要受地质背景控制;不同作物系统元素富集因子表明Pb在土壤-农作物系统中迁移能力最低,Zn迁移能力最强。Cd、Cr、Cu、Ni、Pb和Zn在土壤-水稻系统重迁移能力显著高于蔬菜和玉米。根系土中pH、CaO、有机质、Fe2O3、K2O、MgO与重金生物富集系数呈显著性负相关,但在土壤-叶类蔬菜系统中根系土中K2O、MgO与Hg生物富集系数呈显著正相关。 相似文献
6.
为了解包气带土壤DOM组成特征, 探索其对砷向地下水中迁移的影响, 对江汉平原高砷区土壤DOM进行了三维荧光光谱分析.结果表明DOM主要为类腐殖质成分, 芳香性官能团的减少导致荧光强度随包气带深度增加而变小, 局部深度荧光信号不规则变化指示非均质土壤剖面上DOM组分或主导官能团的变化.平行因子分析表明, DOM组分可更细致地分解为4种组分, 与微生物源的还原、氧化醌类和陆生的腐殖质富里酸类等相似.砷很可能在DOM腐殖质成分络合作用下与之随水体一起向下迁移, 砷的迁移也可能与微生物源的醌类作用过程有关.三维荧光光谱分析准确、快速地刻画了包气带土壤DOM的组分类别及空间变化特征, 初步揭示了DOM影响砷迁移的可能作用方式, 为进一步的地下水砷污染机制的研究提供了重要的参考信息. 相似文献
7.
选用面包酵母菌为吸附菌株,研究了菌株吸附黄铜矿微生物浸出矿液中Cu2+的吸附富集过程,探讨了吸附试验中pH值、温度和初始菌体加入量对Cu2+吸附效果的影响。结果表明:在酵母菌吸附Cu2+的过程中,菌体细胞上的蛋白质酰胺和多糖等成分更多地参与了吸附Cu2+的过程,Cu2+与菌体表面的有机基团结合形成颗粒物沉淀附着在细胞壁上。菌株动力学吸附分析中发现,实验用各菌株对Cu2+的动力学吸附过程除了受菌株种属的影响外,还应与菌株的细胞壁形貌、菌株本身的生长状况的等因素相关。在pH=4.5、t=30℃、初始菌体加入量8.0 g/L的条件下,吸附反应14 h后酵母菌的最佳铜吸附率可达66.64%,面包酵母菌可以吸附富集黄铜矿微生物浸出矿液中的Cu2+,可以有效回收低品位黄铜矿中的铜资源。 相似文献
8.
铁氧化物矿物对苯酚和溶解性有机质表面吸附的初步研究 总被引：2，自引：0，他引：2
文中以铁氧化物矿物对苯酚和溶解性有机质(DOM)的吸附研究为例开展生态矿物学研究。铁氧化物矿物的吸附作用存在多种机制,这些吸附机制发生作用的条件主要取决于溶液化学性质和吸附质的理化性质。批处理实验研究表明,苯酚吸附在酸性微酸性条件下不强,吸附等温线符合Langmuir方程,属于表面分子吸附模型;DOM的吸附强并发生吸附分异,配体交换、憎水键和范氏力等多种模式并存,在酸性中性条件下对DOM在针铁矿上的吸附起着重要贡献。本文实验条件下DOM吸附等温线近于线性,不能采用Langmuir方程拟合,可能原因是DOM浓度较低。矿物表面荷电性对吸附影响显著,例如,当矿物表面净电荷为零(pH=pHpzc)时,矿物表面水化膜减薄甚至消失,苯酚分子、憎水DOM分子或片断都会倾向于在矿物表面上吸附。由于苯酚吸附机制单一,其受到的影响很明显,所以苯酚在pH值7～8范围内出现吸附最大值;由于配体交换作用主要发生在酸性微酸性条件下,所以在本文pH值约7.5的实验条件下,尽管配体交换仍在发生作用,但它不是主要吸附机制,针铁矿对DOM吸附的主要贡献应是憎水键和范氏力作用,此外,DOM吸附等温方程近于线性还可能与此有关。显然,铁矿物表面作用在对有机质含量低而铁矿物含量高的红壤中污染物和DOM的固定与归宿控制中扮演着重要的角色。 相似文献
9.
以位于东北典型黑土区的长春市城乡交错区为研究区,以土壤-作物系统中Cu、As、Pb和Zn为研究对象,采用Pearson相关性分析及土壤和作物综合质量指数对土壤-作物系统地球化学特征及生态风险进行评价。结果显示,表层土壤重金属存在明显的积累现象,作物籽实重金属含量均未超标,作物籽实对土壤中Zn和Cu的吸收富集能力显著高于As和Pb。不同重金属在土壤-作物系统中的迁移能力不同可能与作物种类、pH值、有机质、N、P和K2O含量有关。作物重金属生物富集系数空间分布特征与作物籽实重金属含量空间分布特征相似,与土壤重金属含量空间分布特征存在显著差异。IICQ介于0.13～4.44,均值为0.62。研究区耕地土壤环境质量整体良好,仅中部存在小范围呈圈层分布的风险区域。 相似文献
10.
冻融作用对黑土和棕壤中Pb、Cd吸附/解吸特征的影响 总被引：3，自引：0，他引：3
冻融作用对土壤理化性质具有重要影响,进而影响了土壤中重金属迁移转化过程和环境效应。通过实验模拟研究了冻融作用对黑土和棕壤中Pb、Cd吸附/解吸特征的影响。结果表明：黑土对Pb和Cd的吸附能力大于棕壤;冻融作用降低了土壤对Pb和Cd的吸附能力,这与冻融作用改变了土壤的理化性质有关;随着Pb和Cd吸附量的增大,黑土和棕壤中Pb和Cd的解吸量和解吸率也相应增大;冻融作用促进了黑土和棕壤中Pb和Cd的解吸,并且在同一冻融条件下黑土的解吸能力小于棕壤;冻融作用使得黑土和棕壤对Pb和Cd的解吸量大于未冻融土壤,这与冻融作用使解吸溶液pH的下降幅度增大有关。冻融作用降低了土壤对Pb和Cd的固持能力,增加了土壤中Pb和Cd的生态风险。 相似文献
11.
《Applied Geochemistry》1997,12(3):243-254
Column flow-through experiments reacting wastewater solutions with sandy loam soil samples were performed to study heavy metal attenuation by two soils with different physical and chemical properties. Reacted soil columns were leached with synthetic acid rain to study the mobility of attenuated heavy metals under leaching conditions. This study demonstrates that cation exchange, surface adsorption, chelation with solid organic material, and precipitation were the important attenuation mechanisms for the heavy metals (Cd, Cr, Cu, Mo, Ph, and Zn). Adsorption on soil hydrous oxide surfaces was the primary attenuation mechanism for Cd and Zn in both soils, and for Cu in a soil with low organic matter content. Wastewater solution pH is also an important factor that influences the retention of heavy metals. Cadmium, Cu, Cr, and Zn became mobile after prolonged application of spiked wastewater solution, either through saturation of soil adsorption sites or due to decreasing pH. Only Cr, Pb, and Mo, which are attenuated primarily through precipitation, show significant net retention by soil. Acid rain water removed heavy metals left in the column residual pore solution and weakly sorbed heavy metals in the soils, and has the ability to mobilize some strongly attenuated heavy metals, especially when the soil organic matter content is high. The results have important applications in predicting heavy metal mobility in contaminated soil, the disposal of acid mine drainage, and assessing the risks of landfall leachate leakage. 相似文献
12.
对中国南方的3个水稻土样品进行了Cd、Pb单一离子和混合离子吸附特点的研究。结果表明,3个水稻土样品中Cd、Pb的吸附特点都相似,Langmuir等温方程可很好地描述Cd、Pb的吸附等温线。3个土壤样品中,有较高pH值和较低有机物、CEC浓度、粘土含量、高岭石含量的2个土壤样品对Cd、Pb有较大的吸附量,且其等温吸附拟合的最大吸附量（B）也较大。在两组分混合溶液中,尽管共存离子的存在影响了土壤对单一离子的吸附,同时土壤对Cd的吸附在一定程度上受影响的程度大,但3个土壤样品都表现出对Pb有强的吸附能力。在3个土壤样品中,Langmuir等温方程中Pb的健合能常数（K）都大于Cd的健合能常数（K）,混合溶液中的K值高于单一溶液的K值,表明2种金属离子对吸附位点的竞争提高了特定吸附位点的保持力,使金属离子在土壤中特定位点的吸附更加坚固。 相似文献
13.
水稻土中重金属元素Cd、Pb的竞争吸附
——以长株潭地区水稻土为例 总被引：3，自引：0，他引：3
对中国南方的3个水稻土样品进行了Cd、Pb单一离子和混合离子吸附特点的研究。结果表明,3个水稻土样品中Cd、Pb的吸附特点都相似,Langmuir等温方程可很好地描述Cd、Pb的吸附等温线。3个土壤样品中,有较高pH值和较低有机物、CEC浓度、粘土含量、高岭石含量的2个土壤样品对Cd、Pb有较大的吸附量,且其等温吸附拟合的最大吸附量(B)也较大。在两组分混合溶液中,尽管共存离子的存在影响了土壤对单一离子的吸附,同时土壤对Cd的吸附在一定程度上受影响的程度大,但3个土壤样品都表现出对Pb有强的吸附能力。在3个土壤样品中,Langmuir等温方程中Pb的健合能常数(K)都大于Cd的健合能常数(K),混合溶液中的K值高于单一溶液的K值,表明2种金属离子对吸附位点的竞争提高了特定吸附位点的保持力,使金属离子在土壤中特定位点的吸附更加坚固。 相似文献
14.
A. Mahar P. Wang A. Ali A. H. Lahori M. K. Awasthi Z. Wang Z. Guo Q. Wang S. Feng R. Li Z. Zhang 《International Journal of Environmental Science and Technology》2018,15(3):607-620
The immobilization of heavy metals (HMs)-contaminated soils using amendments is a cost-effective remediation technique. Therefore, the aim of this study was to evaluate the effectiveness and aging factor of CaO, fly ash (FA), sulfur, and Na2S on the immobilization of Cd, Cu, and Pb in three different contaminated soils under 1-year incubation. The study sites (S) and amendments treatments (T) are termed as S1, S2, and S3 and T1, T2, T3, and T4, respectively. The TCLP-extractable HMs were analyzed in treated soils after 2, 6, and 12 months. The higher concentrations of CaO, FA, and Na2S (T3 and T4) efficiently immobilized the Cd. However, a moderate Cd decrease was noted in sulfur-treated samples with no significant difference in ratios as compared to control in used soils. Likewise, CaO decreased moderately Cu content in used soils with gradual increase in Cu mobility. Similarly, FA, sulfur, and Na2S showed effective immobilization of Cu content with no difference in treatment ratios as compared to control. In addition, CaO, sulfur, and Na2S decreased the significant content of Pb as compared to control. However, FA treatments showed moderate reduction in Pb content with no difference in ratios. The higher concentrations of alkaline amendments should be avoided in the farmland soils as they increase the soil pH and EC of soil ecosystem. The higher ratios of alkaline amendments would be suitable to remediate the abandoned lands/brownfields. The sulfur amendment would be suitable for immobilization of metals in alkaline soils rather than in acidic soils. 相似文献
15.
16.
包气带对三氯乙烯的吸附行为研究 总被引：2，自引：0，他引：2
有机污染物在包气带的吸附行为,直接影响有机污染物在环境中的迁移、转化等过程。采用浅层和深层包气带样品,利用批实验的方法研究不同有机碳含量的样品对三氯乙烯(TCE)的吸附行为。研究表明,包气带表层土壤比深层土壤的有机碳含量高,可能存在竞争吸附的问题,说明该土壤的吸附行为是以矿物吸附为主、有机质吸附为辅的类型;表层土壤的吸附具有较好的线性行为,不存在饱和吸附量;深层土壤有机碳含量低,其吸附为非线性的。 相似文献
17.
Simultaneous competitive adsorption behavior of Cd, Cu, Pb and Zn onto nine soils with a wide physical–chemical characteristics
from Eastern China was measured in batch experiments to assess the mobility and retention of these metals in soils. In the
competitive adsorption system, adsorption isotherms for these metals on the soils exhibited significant differences in shape
and in the amount adsorbed. As the applied concentration increased, Cu and Pb adsorption increased, while Cd and Zn adsorption
decreased. Competition among heavy metals is very strong in acid soils with lower capacity to adsorb metal cations. Distribution
coefficients (K
dmedium) for each metal and soil were calculated. The highest K
dmedium value was found for Pb and followed by Cu. However, low K
dmedium values were shown for Zn and Cd. On the basis of the K
dmedium values, the selectivity sequence of the metal adsorption is Pb > Cu > Zn > Cd and Pb > Cu > Cd > Zn. The adsorption sequence
of nine soils was deduced from the joint distribution coefficients (K
dΣmedium). This indicated that acid soils with low pH value had lower adsorption capacity for heavy metals, resulting in much higher
risk of heavy metal pollution. The sum of adsorbed heavy metals on the soils could well described using the Langmuir equation.
The maximum adsorption capacity (Q
m) of soils ranged from 32.57 to 90.09 mmol kg−1. Highly significant positive correlations were found between the K
dΣmedium and Q
m of the metals and pH value and cation exchange capacity (CEC) of soil, suggesting that soil pH and CEC were key factors controlling
the solubility and mobility of the metals in soils. 相似文献
18.
Phosphorus transport in shallow groundwater in peri-urban Kampala, Uganda: results from field and laboratory measurements 总被引：1，自引：0，他引：1
To understand Phosphorus (P) sources and transport processes in the subsurface in Bwaise III Parish, Kampala, P attenuation
and adsorption capacities of soils were studied in situ and from laboratory measurements. Relationships between sorption parameters
and soil matrix properties, rates and mechanism of the adsorption process and soil P fractions were also investigated. P was
generally higher in the wet than the dry season, but for both seasons, the maximum was 5 mgP/l. P transport mechanisms appeared
to be a combination of adsorption, precipitation, leaching from the soil media and by colloids with the latter two playing
an important role in the wet season. The sorption process comprised two phases with the first stage rate constants being about
fourfold those of the second stage. The Langmuir isotherm described the sorption data well (R
2 ≥ 0.95) with the second soil layer exhibiting the highest sorption maximum (C
max) (average value 0.6 ± 0.17 mgP/gDW). The best prediction of C
max had organic carbon, Ca, available P and soil pH. Residual P consisting mostly of organics was the main fraction in all the
layers followed by inorganic HCl-P and NaOH-P in the top and middle layers, respectively. Loosely bound P (NH4Cl-P) was the least fraction (<0.4% of total P) in all layers indicating the high binding capacity of P by the soils. The
study results suggest that P dynamics is related to Ca, Fe and organic carbon content of the soils. 相似文献