镉在土壤中吸附与沉淀的特征与界限   总被引：12，自引：0，他引：12  

费宇红  曹树堂  张光辉  聂振龙 《地球学报》1998,19(4):409-414

吸附和沉淀反应虽然是不同范畴的概念,但是,二者彼此依存,相互作用和制约,二者界限除考虑体系中Ｃｄ量和环境ｐＨ,Ｅｈ等因素外「ＣＯ＾２－３」／「ＯＨ＾－」关系及其质量浓度也是重要因素。在酸性条件下,吸附反应起主控作用;在碱性条件下,沉淀反应起主控作用;在ｐＨ介于６．５－８．５范围,吸附与沉淀综合利用效果最强。  相似文献   

碳羟磷灰石吸附水溶液中镉离子的动力学研究   总被引：19，自引：2，他引：19  

胥焕岩  刘羽  彭明生 《矿物岩石》2004,24(1):108-112

碳羟基磷灰石(CHap)对水溶液中镉离子的吸附过程是一个复杂的非均相固液反应过程，从动力学角度来看，大致可分为两个阶段：初期阶段反应速度快，动力学过程复杂；后期阶段反应速度较慢，并符合一级反应动力学方程。实验表明：反应速率常数k1与温度T之间的关系符合阿累尼乌斯公式，吸附的活化能为Ea=6．075J／mol，吸附的频率因子A=220s^-1。同时，k1与镉离子初始浓度呈负相关性，与介质pH值、CHap用量呈正相关性．  相似文献   

有机-中性化技术对旱作土壤镉有效性的长期影响     

杜葱远  林珍珠  梁巧凤  陈炎辉  王果 《福建地理》2009,(1):15-22

采用连续提取法测定了土壤中镉（Cd）的形态,以研究石灰或钙镁磷肥与猪粪或泥炭混施对田间条件下Cd污染土壤中Cd有效性的抑制效果．处理的第1年,猪粪使石灰对土壤Cd有效性的抑制率从18．2％提高到22．3％,使钙镁磷肥的抑制率从37．1％提高到50．8％;泥炭使石灰的抑制率从18．2％提高到57．1％,使钙镁磷肥的抑制率从37．1％提高到49．3％．处理的第4年,猪粪使石灰对土壤Cd有效性的抑制率从32．3％提高到44．2％,使钙镁磷肥的抑制率从38％提高到51．6％;泥炭使石灰的抑制率从32．3％提高到45．4％,使钙镁磷肥的抑制率从38％降低到8．2％．上述结果表明猪粪和泥炭在施用后第1年均可增强石灰和钙镁磷肥对土壤Cd有效性的抑制效果．到第4年,猪粪仍然促进了石灰和钙镁磷肥对Cd有效性的抑制效果,而泥炭增强了石灰的抑制效率但降低了钙镁磷肥的抑制效果．研究结果证明了有机-中性化技术对cd污染土壤的修复效果．石灰和钙镁磷肥大幅度提高了土壤Cd的碳酸盐结合态与专性吸附态,从而降低了土壤Cd的有效态（水溶态＋交换态）．  相似文献   

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  

刘旭  顾秋蓓  杨琼  余涛  张起钻 《现代地质》2017,31(2):374

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407%。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60是象州土壤Cd活动态含量的突变点,pH值在60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   

膜去溶-电感耦合等离子体质谱法测定环境地质样品中的镉   总被引：3，自引：3，他引：0  

王岚  杨丽芳  谭西早  武朝辉 《岩矿测试》2017,36(6):574-580

应用电感耦合等离子体质谱法(ICP-MS)分析环境地质样品中的Cd时,Zr、Mo元素的氧化物和氢氧化物会对Cd造成严重干扰,导致结果有明显的偏差。针对此问题,本文建立了膜去溶-ICP-MS直接测定环境地质样品中微量Cd的分析方法,该方法可有效地消除Zr、Mo氧化物和氢氧化物对Cd的干扰,保证结果准确、可靠。膜去溶-ICP-MS相比于常规ICP-MS测定Cd的方法,可将Zr、Mo氧化物和氢氧化物对Cd的干扰降低到0.001%,检测灵敏度提高3.5倍左右。在给定条件下,Cd的检出限为0.28 ng/L,测定下限为2.2 ng/L,精密度(RSD,n=12)为2.2%。利用该方法分析20种岩石、土壤和沉积物国家标准物质的测定值与标准值相符,表明膜去溶-ICP-MS法直接测定环境地质样品中痕量或超痕量Cd时具有一定的应用潜力。同时,用该方法对2016年中核集团组织的实验室间两个比对样品中的Cd进行测定,稳健Z比分数分别为0.500和-0.964,Z的绝对值都小于2。  相似文献   

长江三峡库区土壤与水系沉积物Cd地球化学特征   总被引：11，自引：0，他引：11  

唐将  刘安云  邓富银  雷家立 《地质通报》2005,24(8):750-754

对长江三峡库区段不同介质中Cd的分布特征和长江水系沉积物在垂向、横向剖面上的元素分布特征的研究发现，残坡积型土壤与长江干流水系沉积物Cd含量差异较大，水系沉积物具明显的高Cd异常；各个沉积时期的水系沉积物中均存在Cd异常，上游来源的Cd是引起三峡库区水系沉积物高Cd异常的主要因素；人类活动对土壤和水系沉积物中Cd的含量影响明显，在厂矿、码头、生活垃圾场等地区土壤中Cd的含量远高于一般地区土壤中Cd的含量，城市排污水系沉积物Cd的含量也高于长江干流水系沉积物Cd的含量。自然源是沿长江流域Cd异常普遍存在的根本原因，而人为源却有可能是高Cd异常主要沿长江干流及支流两岸大中城市分布的重要影响因素。  相似文献   

Trends in atmospheric Cd deposition recorded in a 64-meter long ice-core and a 5-m snow pit record from Devon Island, Nunavut, Canada     

Yaping WANG Chunxue XU Suming WANG Ziyi AN 《中国地球化学学报》2006,25(B08):15-15

Along with the rapid development of science and technology, natural matter and energy are further exploited and used. The pollution imposed on nature has also sharply increased. Only do we know the pollution history, can we make a correct appraisal of local environment, get the hold of the main cause of environmental pollution, and then take the effective measures to control the environment？ The evolution of heavy metal concentrations with time in the soil environment in the southern suburbs of Beijing were studied by using annual growth rings of trees. The absorption of 12 elements by different tree species in the same soil type was studied according to their absorption coefficients. The study indicated the differences in adsorption of elements by different species of trees. The adsorption coefficients of the elements Zn, Cd and P are higher. The correlations of nine elements （Na, K, Cu, Zn, As, Sr, Cd, Ba and Pb） in growth rings of poplar trees and those in soils near their roots show that the element contents in growth rings have a positive correlation with the contents in soils near the roots. Based on the logarithmic linear correlation model, the evolution of the contents of the elements Cu, Zn, As, Cd, Ba and Pb in soils from 1982 to 2004 was deduced. The trees have the characters of confirming year precisely, long life and widespread distribution. They are the ideal objects of study on environmental pollution changes. At present, research in China in this aspect is less, and the field of research is expected to further expand. This method can be used to provide richer and more scientific information on the history of environmental pollution and changes during modem urbanization in the past few decades and predicting the evolutionary trend of pollution change.  相似文献   

Pore water trace metal chemistry in polluted sediments of a tropical estuary of SE Brazil     

Sambasiva Rao Patchineelam Edouard Metzger Didier J uel Gerard Sarazin 《中国地球化学学报》2006,25(B08):66-67

The Sepetiba Bay is a shallow water body semi enclosed located on the west side of Rio de Janeiro City. Almost 80% of flesh water discharge, from the St Francisco canal, coming from the northern side of the bay develops an estuarine environment. Fishing and tourism are some of the most important economic activities in the area. During 35 years a zinc/cadmium smelter has polluted the bay. The objective of this investigation is to demonstrate the diagenetic processes and cadmium remobilization into pore water from the contaminated sediments. Two sites were selected to compare diagenetic processes. Site P1 is located next to domestic effluents discharge into the bay and approximately 20km away from the smelter. Site P2 is located near the same smelter and next to the Mazomba estuary, which is not influenced directly by domestic effluents. Peeper samplers of 25 cells with a resolution of 2.5 cm were deployed at both the sites. After a 3-weeks period of equilibrium, the pore waters were separated from the cells and analyzed immediately （within 24 h） for alkalinity, NH3 and reactive soluble phosphorus on a spectrophotometer. An ICP-AESΣH2S spectrometer was used to analyze Na, Mg, Li, Ba, Sr, Si, Fe and Mn. Total and labile dissolved Cd in pore waters were determined by differential-pulse stripping voltametry. The dissolved constituents in the pore waters have shown that the intensities of diagenetic reactions are different between sites. The reactions are stronger at site P1 site than at site P2, especially between 7.5 cm and 22.5 cm, which is evident by the organic rich sediment.  相似文献   

断续流动在线分离富集-蒸气发生原子荧光光谱法测定复杂环境样品中痕量镉     

李中玺  周丽萍 《岩矿测试》2006,25(3):233-238

用D201阴离子交换树脂富集样品中的痕量Cd，使Cd与共存干扰元素Cu、Ni、Pb、Zn有效分离，消除了这些元素对镉蒸气发生的干扰，从而建立了断续流动在线分离富集-蒸气发生原子荧光光谱法测定复杂环境样品中痕量Cd的分析方法。方法的检出限为3ng／L（3σ）；测定精密度（RSD）为1．9％（对1μg/L Cd，n=11）。用该方法对国家一级标准物质（土壤、水系沉积物和岩石）中的痕量镉进行了测定，结果与标准值相符。  相似文献   

福建龙岩中甲铁矿床中铟、镉赋存状态及其综合回收经济评价          下载免费PDF全文

毛光武  朱玉磷 《地质找矿论丛》2013,28(1):58-64

福建龙岩中甲铁矿是上世纪60年代探明的海相火山沉积-热液叠加改造型多金属硫化物磁铁矿矿床。随着该矿难选铁矿石选矿技术的突破,最近发现矿石中共(伴)生的分散元素铟、镉含量超过综合利用工业最低品位要求,铟、镉的储量估算均可达大型规模。通过研究铟、镉的赋存状态,认为矿石中尚无铟、镉的独立矿物存在,铟、镉主要与锌呈类质同象存在于闪锌矿的晶格中;铟、镉综合回收经济评价表明,铟、镉在选矿流程中主要走向锌精矿,可在锌的冶炼过程中综合回收,并会获得很好的经济效益。永安—梅县凹陷带内有众多与该矿床类似的铁多金属矿,该矿床共(伴)生铟、镉含量及赋存状态的考察,对区域同类矿床伴生元素的综合利用、提升经济价值有重大意义。  相似文献