共查询到19条相似文献，搜索用时 140 毫秒
1.
湿地水环境中表层沉积物吸附铅、镉能力的研究 总被引：6，自引：2，他引：6
在选定的实验条件下,对向海自然保护区5个不同类型湿地水体的表层沉积物样品进行了铅、镉的热力学吸附实验.结果表明,沉积物样品吸附铅、镉的过程符合Langmuir和Freundlich(n=8,p= 0.01) 等温吸附曲线.在所讨论的范围内,沉积物样品吸附铅、镉的能力与样品中铁、锰氧化物及有机质含量存在着显著的相关性.表层沉积物吸附铅、镉的能力小于生物膜吸附铅、镉的能力,即在湿地水环境中,生物膜对重金属迁移转化的作用相对于表层沉积物而言更重要. 相似文献
2.
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
3.
土壤中铅铜锌镉的吸附特性 总被引：5，自引：0，他引：5
以徐州王庄矿（WZK）、奎河（KH）、背景-1（BG-1）和背景-2（BG-2）等4个土壤样品为供试对象，加入不同浓度梯度的铅、铜、锌、镉离子，通过静态实验研究了铅、铜、锌、镉的吸附特性。结果表明，土壤对4个重金属的吸附量与加入到土壤中的重金属离子浓度呈正相关性，它们之间大部分满足线性相关关系。在4个土壤样品中加入铅、铜、锌、镉离子的初始浓度比为10：10：10：1时，平衡浓度为Czn〉Ccu〉CPh〉Ccd，吸附量为Scd〉SPh〉Scu〉Szn，4个土壤样品对铅、铜、锌、镉离子的吸附能力依次为WZK〉KH〉BG-2〉BG-1。在所选实验条件下，土壤对铅、铜、锌、镉的吸附能力受土壤中铅、铜、锌、镉的含量、土壤有机质含量、阳离子交换量、土壤饱和含水量和土壤的pH值影响较大。 相似文献
4.
为揭示旱地和水田土壤镉的吸附解吸特征,以江汉平原黄豆地、棉花地以及水稻田土壤为研究对象,开展土壤镉的吸附动力学实验、等温吸附-解吸实验以及有机质的影响实验.结果表明:江汉平原土壤对镉的吸附是一个较为复杂的吸附动力学过程且以化学吸附为主,研究区土壤镉的初始吸附速率总体上表现为水田土壤大于旱地土壤;旱地土壤对Cd2+具有较低的吸附能力和较高的解吸能力,水田土壤对Cd2+具有较高的吸附能力和较低的解吸能力,这与土壤有机质含量、土壤粘粒含量等因素有关;去除有机质后旱地、水田土壤对镉的吸附量均明显下降,且旱地土壤降幅更为明显,水田土壤去除有机质后对Cd2+的吸附能力依然高于旱地土壤.研究结果可为不同类型农田土壤的镉污染修复提供理论依据. 相似文献
5.
自然水体生物膜、悬浮颗粒物和沉积物吸附铅、镉的热力学参数比较 总被引：12，自引：5，他引：7
采用实验室模拟的方法研究了松花江自然水体生物膜、悬浮颗粒物和沉积物吸附铅、镉的热力学规律。根据吸附热力学参数(Γmax、k和Kd)综合比较3种固相物质的吸附能力,并讨论吸附能力存在差异的原因。结果表明:Langmuir型及Freundlich等温式可以很好地描述3种固相物质吸附热力学规律,三者吸附铅、镉的能力为生物膜>悬浮颗粒物>沉积物,生物膜、悬浮颗粒物和沉积物对铅的吸附能力均明显高于对镉的吸附能力。 相似文献
6.
不同粒级土壤中镉铅汞的吸附特性 总被引：2，自引：0，他引：2
将3种不同质地的土壤样品分为3种不同的粒级:自然状态、砂粒和粉黏粒,分别研究了这3种不同土壤在3种不同粒级时对镉、铅、汞的吸附特点。结果表明,镉、铅在粉黏粒土壤中的吸附大于在自然土壤和砂粒土壤中的吸附,而汞却表现出相反的结果,其在砂粒土壤中的吸附远远大于在粉黏粒土壤和自然土壤中的吸附。3种不同质地的土壤对镉、铅、汞的吸附与分粒级土壤的吸附表现出了相似的吸附特性。同时,镉在3种不同土壤不同粒级中的吸附符合Langmuir方程,铅在3种不同土壤不同粒级中的吸附符合Henry方程,而汞在3种不同土壤不同粒级中的吸附符合Freundlich方程。 相似文献
7.
汞和镉在土壤中的吸附和运移研究进展 总被引：20，自引：2，他引：20
介绍了国内外近年来对重要的污染元素汞和镉在土壤中吸附和运移方面的研究成果。评价土壤吸附重金属离子多运用Langmuir、Freundlich及Temkin三种等温吸附曲线。影响土壤吸附汞和镉的因素主要有pH值、有机质、氯离子、土壤组分、土壤类型、竞争吸附离子的参与等。汞的活动性较差，其迁移性质缺乏研究；土壤中镉的二价离子在粘土衬层内的迁移过程中，可生成难溶性沉淀物质，阻碍了液体的渗透，因而导致渗透系数比纯水还低。引用参考文献45篇。 相似文献
8.
辽河流域土壤镉有效性的地球化学研究 总被引：2，自引：0，他引：2
利用辽宁省辽河流域生态地球化学调查中取得的土壤镉深表层含量及形态分析等测试数据,对土壤镉的存在形态及其影响因素进行了系统对比研究,结果表明：辽河流域土壤镉主要以离子交换态、水溶态、铁锰氧化态、碳酸盐结合态、强有机结合态、腐殖酸结合态及残渣态等七种形态存在,其中离子交换态及水溶态是可被生物吸收利用的有效态,其含量主要受土壤镉全量、pH值、有机质、土壤粘度等因素制约。 相似文献
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11.
D. Arenas-Lago M. Lago-Vila A. Rodríguez-Seijo M. L. Andrade F. A. Vega 《Environmental Earth Sciences》2014,72(7):2541-2556
The risk of Pb, Zn and Cd mobility is evaluated in soils from a depleted mine at Rubiais (Lugo, Spain). This area is under special protection because of its outstanding natural value. Soils from nine different areas were selected: at the mining zone (R1, R2, R3), at minespoils (R4, R5, R6) and soils developed on the settling pond (R7, R8, R9). A control soil (RC) was sampled outside the mine. The objectives are (i) to study the characteristics of soils with high influence on metal retention, (ii) to determine the content of Pb, Zn and Cd comparing it with the generic reference levels, and (iii) to evaluate the distribution and the interactions between the metals and the soil geochemical phases by means of sequential chemical extraction, X-ray diffraction, field emission scanning electron microscopy/energy-dispersive X-ray spectroscopy (FE-SEM/EDS) and time of flight secondary ion mass spectrometry (TOF–SIMS). The concentration of Pb, Zn and Cd ranges 850–6,761, 1,754–32,287 and 1.8–43.7 mg kg?1, respectively, and the highest proportion is in the residual fraction. The Mn oxides highly influence the retention of Cd while Pb retention is mainly influenced by Fe oxides. Zn is uniformly distributed amongst the residual fraction and the Fe and Mn oxides. TOF–SIMS and SEM/EDS techniques confirm the fractionation results, showing how Pb and Zn are as sulphide and associated with Fe and Mn oxides. Nevertheless, care should be taken since oxides and sulphides could suffer sulphide oxidation processes or alteration of the oxides causing leaching and the contamination of the protected ecosystem. 相似文献
12.
Donald L. Suarez 《Geochimica et cosmochimica acta》1976,40(6):589-598
Soils of loamy sand on weathered, sandy dolomite were cored from six holes up to 70 ft beneath a municipal waste landfill in central Pennsylvania. Mn, Fe, Ni, Co, Cu, Zn, Cd, Pb, and Ag were determined in exchangeable and non-exchangeable forms in total and < 15 μm soil samples. Most of these metals were bound in Mn oxides, non-exchangeable with 0.5 M CaCl2. The Mn oxides (often X-ray amorphous) identified when crystalline as todorokite occurred chiefly as coatings on quartz grains.Somewhat higher amounts of acid leachable trace metals were found in the < 15 μm size fraction than in the total soil samples; however, trace metal/Mn ratios were similar in both. In general, the initial mild soil leaching, which dissolved chiefly Mn oxides, gave MnFeX>Co>Ni>Pb>Zn> Cu>Cd>Ag. The final leaching, which dissolved chiefly ferric oxides, gave Fe>Mn>Ni>Zn>Co> Cu>Pb>Cd>Ag. Samples taken from an unpolluted site and from the same soils affected for seven years by leachate from the refuse had similar metal contents.Soil extractable Co, Ni, Cu, and Zn could be predicted from the Mn extracted. Based in part on factor analysis of the data, Mn-rich oxides had at least tenfold higher heavy metal percentages than Fe-rich oxides (crystalline component goethite), reflecting their greater coprecipitation potential. Because of this potential and because of the generally higher solubility of Mn than Fe oxides, more heavy metals may be released from Mn-rich than from Fe-rich soils by disposal of organic-bearing wastes. However, leaching of the moisture-unsaturated soils in situ is rarely severe enough to completely dissolve both Mn and Fe oxides. Based on the Mn content, Cd, Cu, and Pb were depleted in soil moisture beneath the landfill relative to their amounts in the soil. This depletion may reflect factors including heterogeneity in metal content of the soil oxides; preferential resorption of these metals; and removal of the Cd, Cu, and Pb as organic precipitates or as inorganic precipitates such as carbonates. 相似文献
13.
Daniel G. Strawn Patrick Hickey Andrew Knudsen Leslie Baker 《Environmental Geology》2007,52(1):109-122
To remediate Pb contaminated soils it is proposed that phosphorus can be amended to the soils to transform the Pb into poorly
soluble Pb-phosphate mineral phases. However, remediation strategies must account for variable Pb speciation and site-specific
factors. In this study soil mineralogy and Pb speciation in soils from P-amended field trials at sites within the Coeur d’Alene
River Basin in Idaho, USA were investigated. The soils are contaminated from mining activities and are enriched with Fe and
Mn. Selective extraction of the soils indicated that the Fe oxides are poorly crystalline. XRD of the soil clay size fractions
identified quartz, muscovite, kaolinite, siderite, lepidocrocite, and chlorite minerals. Amendment with P fertilizer dissolved
the siderite. No Pb–phosphate minerals were detected by XRD. Electron microprobe analysis showed direct correlations between
Pb, Fe, and Mn in the unamended soils, and negative correlations between Pb and Si. Lead and Mn were strongly correlated.
In the amended soils Fe and P were strongly correlated. Results indicate that the Pb is associated with poorly crystalline
Fe and Mn oxides, and that added P is primarily associated with Fe oxide phases. Comparisons of pore water Pb concentrations
with chloropyromorphite and plumbogummite solubility suggest that in the phosphate-amended soils the pore waters are undersaturated
in these phases, whereas several of the control soil pore waters were oversaturated, indicating the added phosphate suppressed
the Pb solubility. Results from this research provide insight into the geochemistry occurring in the P-remediated soils that
will help in making management and remediation decisions. 相似文献
14.
Effects of Heavy Metal Contamination on Microbial Biomass and Community Structure in Soils 总被引：5，自引：0，他引：5
Theeco environmentalpollutioncausedbyminingdevelopmentisaworldwideproblem ,whichhasarousedever increasingattentionofscientists.Inadditiontovegetationdestructionanderosionofcultivatedlanddirectlycausedbyminingdevelopment,scientistshaveplacedmorefocusontheenvironmentalproblemsinducedbythereleaseofharmfulsubstances ( particularlyheavymetals) .Especiallyundersurfaceconditions,thepiled upminewastes (minetailings)undergoweatheringundertheactionofaseriesofgeochemicalfactorssuchasthemineralogyofmineta… 相似文献
15.
广西象州与横县碳酸盐岩分布区土壤中Cd形态分布特征及影响因素 总被引：2，自引：0，他引：2
广西壮族自治区碳酸盐岩分布面积为96 372 km2,约占全区陆地国土面积的407%。由碳酸盐岩风化形成的土壤中Cd、Pb、Hg等重金属元素普遍富集。初步评价发现,农作物籽实对Cd的吸收量与土壤Cd含量无对应关系,农作物Cd超标多出现在土壤Cd含量较低的地区。进一步研究发现,Cd高含量的土壤中普遍含有铝土矿、Fe Mn结核等颗粒。为了探索土壤中Cd存在形态及其影响因素,选择了含铝土矿和铁锰结核的横县土壤和无铝土矿与铁锰结核的象州土壤,系统研究了土壤Cd形态差异及其影响因素。结果表明：(1)象州土壤中Cd主要以活动态形式存在,生物可利用性高,横县土壤中Cd主要以稳定态形式存在,生物可利用性低。(2)pH值为60是象州土壤Cd活动态含量的突变点,pH值在60处含量达到最大值;而在横县,pH降低使活动态Cd比例增加。(3)象州土壤中活动态Cd随有机质增加而增加,表明Cd被有机质弱吸附;而横县土壤有机质含量与Cd形态无明显相关性。(4)由铝土矿导致的土壤高Cd含量,多以残渣态形式存在,不会对动植物造成危害。 相似文献
16.
Comparison of trace metal adsorption onto different solid materials and their chemical components in a natural aquatic environment 总被引：1，自引：0，他引：1
Solid materials such as suspended particulate matter (SPM), deposited sediment (DS) and natural surface coatings (NSC, composed of biofilms and associated minerals) are important sinks and potential sources of pollutants in natural aquatic environments. Although these materials can exist in the same water body, few studies have been conducted to compare their ability to adsorb trace metals. In this study, the adsorption of Pb, Cu and Cd by these solids, collected from an urban lake, was investigated. In addition, the metal adsorption properties of the main components of these solids, namely Mn and Fe oxides and organics, were also investigated using the method of selective extraction followed by metal adsorption. The solids that co-existed in water showed similarities and differences in their compositions. For each metal, adsorption to the solids occurred in the same order: NSC > SPM > DS. For Pb and Cd, Fe and Mn oxides and organics contributed to the adsorption by NSC and SPM, and the adsorption by DS was dominated by Fe oxides. For Cu, the organics were the main adsorptive phase. The specific adsorption capability of these components decreases in the following order: Mn oxides > Fe oxides > organics. Overall, the results presented herein indicate that different solids and their components played important roles in the adsorption of trace metals. 相似文献
17.
Selenium and heavy metals content in some Mediterranean soils 总被引：1，自引：0，他引：1
L. Roca-Perez C. Gil M.L. Cervera A. Gonzálvez J. Ramos-Miras V. Pons J. Bech R. Boluda 《Journal of Geochemical Exploration》2010
The study of metal contents in industrial, agricultural or/and polluted soils compared with natural or unpolluted soils is currently necessary to obtain reference values and to assess soil contamination. Nonetheless, very few works published appear in international journals on elements like Se, Li and Sr in Spanish soils. This study determines the total levels of Se, Li, Sr, As, Cd, Co, Cr, Cu, Ni, Pb, V, Zn, Fe, Mn and Ba in 14 natural (unpolluted) soils (Gypsisols, Leptosols, Arenosols and Acrisols), 14 agricultural soils (Anthrosols, Fluvisols and Luvisols), and 4 industrial–urban affected-surface soil horizons (Anthrosols and Fluvisols) of Eastern Spain. The geochemical baseline concentrations (GBC) and reference values (RV) have been established, and the relationships among elements and also between soil properties and elemental concentrations have been analysed. The RV obtained in this study were (mg kg−1): Se 2.68, Li 115, Sr 298, Cd 0.97, Co 35, Cr 217, Cu 46, Ni 50, Pb 137, V 120, Zn 246, Fe 124,472, Mn 2691, and Ba 743. The RV for Se and Li were used as a preliminary approach to assess soil contamination in Spanish soils. The results confirm human impact on Sr, As, Cd, Cr, Cu, Ni, Pb and Zn soil concentrations, but evidence no deviation from natural Se, Li, Co, V, Fe, Mn and Ba concentrations. The results obtained from the statistical analysis reveal significant correlations between some elements and clay and soil organic matter (SOM) contents, indicating that metal concentrations are controlled by soil composition. One particularly interesting finding is the high correlation coefficients obtained between SOM and Se, Cd, Cr, V, Fe, and Mn, and between clay and Cd, Zn, V, Fe and Mn. Once again, these facts confirm the role of SOM and clay minerals in soil functions and that soil is an ecosystem element responsible for maintaining environmental quality. 相似文献
18.
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
19.
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