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1.
The mobility of toxic metals in soils or sediments is of great concern to scientists and environmentalists since it directly affects the bioavailability of metals and their movement to surface and ground waters. In this study, a multi-surface soil speciation model for Cd (II) and Pb (II) was developed to predict the partition of metals on various soil solid components (e.g. soil organic matter (SOM), oxide mineral, and clay mineral). In previous study, the sorption of metal cations on SOM and oxide minerals has been evaluated by thermodynamically based surface complexation model. However, metal binding to soil clay fractions was normally treated in a simplistic manner: only cation exchange reactions were considered and exchange coefficient was assumed unity. In this study, the binding of metals onto clays was described by a two-site surface sorption model (a basal surface site and an edge site). The model was checked by predicting the adsorption behavior of Cd (II) and Pb (II) onto three selected Chinese soils as a function of pH and ionic strengths. Results showed that the proposed model more accurately predicted the metal adsorption on soils under studied condition, especially in low ionic strength condition, suggesting that adsorption of metals to soil clay fractions need to be considered more carefully when modeling the partition of trace elements in soils. The developed soil speciation model will be useful when evaluating the movement and bioavailability of toxic metals in soil environment. 相似文献
2.
A review with 227 references of the title subject is presented. It is divided into two main sections, viz., nature and properties of humic matter, and water—metal—sediment interactions.The first section deals with the essential properties of organic matter which occurs naturally in drainage sediments and waters. Discussion of the basic molecular structure of humic and fulvic acids is followed by some details of the chemical nature of functional groups within these structures which are important in metal-ion adsorption and complexing reactions which these materials can undergo. Information is also presented for colloidal and polyelectrolyte properties, complexation properties, and finally a summary discussion of metal-ion—humic-acid, metal-ion—fulvic-acid stability constants for both single ligand and mixed ligand systems completes the section.The second section comprises discussions of some specific aspects of interactions between metals, sediments and waters, including metal and organic speciation studies; sorption interactions between organic matter, clays and humic acids; chemical reaction between humic acids, heavy-metal minerals, clays and other silicate minerals; metal-ion adsorption—desorption studies, oxidation—reduction reactions between metal ions and humic acids; effects of sulphide ion on some of the above interactions and finally a summary of some relevant field geochemical dispersion studies.This second section describes both laboratory and field studies for each aspect. 相似文献
3.
Organic-rich sediment samples collected from a transect within, and below, the Oman Margin oxygen minimum zone (OMZ) were analysed using a sequential leaching technique to characterise the diagenetic behaviour and speciation of Mn and Fe in operationally defined sediment host fractions. Trace metals showed distinct diagenetic behaviour in the two contrasting environments that were sampled. The absence of non-detrital Mn in the cores below the OMZ site is attributed to the lack of easily reducible oxides in surficial sediments and to the reduction and export of any moderately reducible aged oxides. The reactive form of solid phase Mn showed a classic feature of enrichment in the upper layer of the sediments at the abyssal site, reflecting the presence of an oxidising sedimentary layer which acts as a Mn trap during its recycling. The diagenetic Mn enrichment was inferred from typical downcore colour changes and an upward-increasing Mn content in the upper core sections. An easily reducible Fe oxide layer was observed in the abyssal sediments at an identical depth to the Mn enrichment suggesting that Fe associated with Mn oxides also has undergone sub-oxic diagenesis. However, the association of Fe with organic matter did not indicate diagenetic modification; i.e., the binding strength of the metal with organic materials appears to be sufficiently strong to preserve the trace metal. The speciation signature of non-detrital Fe differed from that of Mn. The association of Fe with organic matter suggests that this metal does not undergo diagenetic modification and is preserved in abyssal sediments. The contrasting behaviour of Mn and Fe observed between cores within the OMZ were particularly interesting. Another interesting observation was that, for cores below the OMZ, the iron oxides were associated with the Mn-oxide peak, rather than deeper in the sediments as observed by earlier studies in the Atlantic [Froelich et al. (1979). Geochim. et Cosmochim Acta
43, 1075–1090].This revised version was published online in May 2005 with corrections to the article title. 相似文献
4.
Nowadays, the Fe-C coprecipitate mechanism is recognized by more and more scholars and becomes the hot topic in the environmental science. On the basis of discussing the interaction between iron oxide and organic matter, and the adsorption research progress of Fe-C complexes on heavy metals, the immobilization potential of Fe-C complexes on heavy metals in polluted soil were illustrated. The surface properties and physical characterizations of iron oxide are changed regularly with the interaction of organic matter, which lead to the higher adsorption capacity of Fe-C complexes in contrast to single iron oxide. Besides, the influences of pH values, organic matter types and surface properties of iron oxides on the adsorption capacity of Fe-C complexes on heavy metals were discussed. The excellent adsorption performance of Fe-C complexes in certain conditions will provide important theoretical basis for contaminated soil remediation. 相似文献
5.
Hydrochemical monitoring and heavy metal speciation by sequential extraction techniques indicate direct relationships among enrichment of the heavy metals (copper, lead, zinc, iron, manganese, and cadmium), soil acidification, and salinization in Kedron Brook floodplain area of Brisbane, Australia. Assessment of modes of occurrence and distribution pattern of the heavy metals in soil, sediment, and water environments of this coastal plain indicates that the total concentrations and reactive fractions of these metals are elevated in soil and channel bed sediments. Such geochemical signatures reflect the complex influence of sources and a combination of natural and anthropogenic processes on concentration and dispersion within the coastal zone. According to a working model presented, the enrichment of the heavy metals, like cadmium, in the soil and sediment profiles is triggered by capillary pumping during low groundwater standing levels, when the metals are in a stable form associated with dry gels. During higher groundwater levels and occasional flood events, these metals become mobilized when the gel material is transformed into soluble colloidal phase.This study indicates that the potential impacts of heavy metal pollution on the coastal ecosystems can not be assessed and managed in isolation solely by considering the natural cause-effect relationships. The complex nature of sediment-soil-water interactions in the coastal hydrodynamic zones can produce a manifold of effects, including mobilization, concentration, and/or dispersion of heavy metals at both short and longer time scales. In the case of Kedron Brook, chemical erosion due to variation in natural climatic and hydrodynamic conditions contributes significantly to concentration of heavy metals in the coastal environments. Therefore, a sound understanding of the prevailing hydrogeochemical processes is essential for prediction of the fate of heavy metals and establishment of meaningful coastal zone management strategies. 相似文献
6.
铁锰氧化物在污染土壤修复中的作用 总被引：22，自引：0，他引：22
矿物学在环境科学中的应用将是21世纪矿物学研究的一个主要方面。土壤污染作为一个制约人类社会可持续发展的基本问题正受到日益广泛的关注，污染土壤的修复已成为环境科学研究的一个重点。污染土壤的修复技术主要有物理、化学、生物等方法，但是，它们都不同程度地存在着缺陷。众所周知，铁和锰是自然界中少数但常见的变价元素。含有变价元素和带有表面电荷的铁锰氧化物具有良好的表面活性，不仅对有毒有害的无机污染物具有良好的净化功能，而且对土壤中有机污染物具有氧化降解作用。利用这些矿物来修复污染土壤，具有成本低、无二次污染等优点，体现出天然净化作用的特色，展现出广阔的环境矿物学应用前景。 相似文献
7.
福建龙海土壤重金属含量特征及影响因素研究 总被引：1，自引：0，他引：1
为有效预防土壤重金属生态风险,以福建龙海市表层土壤为研究对象,应用经典统计分析、随机森林等方法,研究重金属元素含量特征及其影响因素。结果表明：(1)第四纪冲洪(海)积成因水稻土中多数重金属元素含量较高;(2)燕山期中酸性岩风化形成的残坡积红壤中重金属元素活动态含量较高;(3)As、Cu、Ni形态含量与全量相关性较好,而Cd、Cr、Hg的多数形态含量与全量相关性较差;(4)除元素全量外,土壤有机质对弱有机结合态重金属(不包括Ni、Pb元素)以及离子交换态、碳酸盐结合态Cd、Zn有重要影响,阳离子交换量对各形态Ni,(Fe×Al)/Si对各形态Cu具有重要影响,而土壤成因、土壤类型对重金属形态组成的影响较小。研究表明土壤重金属形态组成及其富集区与其全量不尽一致,土壤重金属生态风险评价应考虑土壤重金属形态分布特征。 相似文献
8.
对于人为因素或自然因素造成的农田土壤重金属元素污染,需要进行大面积的土壤环境质量调查和分类管控,然而传统的采样测试方法存在工作量大、代价高等问题。可见—近红外（Vis-NIR）反射光谱是一种快速低成本获取土壤理化信息的手段。为研究Vis-NIR反射光谱预测模型划分土壤重金属污染风险类别的能力,文章以典型人为污染地区（浙江温岭）和典型地质高背景地区（广西横县）的390份农田土壤为样本,测定8种重金属元素（As、Cd、Cr、Cu、Hg、Ni、Pb和Zn）的含量和pH值,并测定土壤Vis-NIR光谱。使用偏最小二乘（PLS）和支持向量机（SVM）算法建立回归模型,对土壤重金属含量和pH值进行预测,并基于预测值进行土壤重金属污染风险分类。结果显示,温岭土壤主要污染元素Cd和Cu的光谱模型回归预测偏差（RPD）分别为1.23和1.19,预测机制与有机质有关。横县土壤主要污染元素As和Cd的RPD分别为1.98和1.93,预测机制与铁氧化物和粘土矿物有关。地质高背景土壤重金属与铁氧化物的正相关性普遍较强,使得光谱模型对重金属含量预测准确度较高。温岭和横县土壤pH值的光谱模型RPD分别为1.76和1.68。土壤重金属污染风险光谱分类的总体
准确度分别为75.0%~100%（温岭）和80.0%~100％（横县）。将Vis-NIR光谱与遥感技术相结合,对农田土壤重金属污染风险进行快速分类总体是可行的。 相似文献
9.
R. R. Haese J. Schramm M. M. Rutgers van der Loeff H. D. Schulz 《International Journal of Earth Sciences》2000,88(4):619-629
Pore water and solid phase from surface sediments of the continental slope off Uruguay and from the Argentine Basin (southwestern Atlantic) were investigated geochemically to ascribe characteristic early diagenetic reactions of iron and manganese. Solid-phase iron speciation was determined by extractions as well as by Mössbauer spectroscopy. Both methods showed good agreement ( <6% deviation) for total-Fe speciation. The proportion of easy reducible iron oxyhydroxide relative to total-Fe oxides decreased from the continental slope to the deep sea which is attributed to an increase in crystallinity during transport as well as to a general decrease of iron mobilization. The product of iron reoxidation is Fe oxyhydroxide which made up less than 5% of total Fe. In addition to this fraction, a proportion of smectite bound iron was found to be redox reactive. This fraction made up to 10% of total Fe in sediments of the Argentine Basin and was quantitatively extracted by 1?N HCl. The redox reactive Fe(+II) fraction of smectite was almost completely reoxidized within 24?h under air atmosphere and may therefore considerably contribute to iron redox cycling if bioturbation occurs. In the case of the slope sediments we found concurrent iron and manganese release to pore water. It is not clear whether this is caused by dissimilatory iron and manganese reduction at the same depth or dissimilatory iron reduction alone inducing Mn(+IV) reduction by (abiotic) reaction with released Fe2+. The Argentine Basin sediment showed a significant manganese solid-phase enrichment above the denitrification depth despite the absence of a distinct pore-water gradient of Mn. This implies a recent termination of manganese mobilization and thus a non-steady-state situation with respect to sedimentation or to organic carbon burial rate. 相似文献
10.
Heavy metal mobility assessment in sediments from the Odiel River (Iberian Pyritic Belt) using sequential extraction 总被引：1，自引：1，他引：0
Rafael Beltrán J. D. de la Rosa J. C. Santos M. Beltrán J. L. Gómez-Ariza 《Environmental Earth Sciences》2010,61(7):1493-1503
The Tessier sequential extraction scheme (SES) was applied to sediments from the Odiel river catchment (Iberian Pyritic Belt,
SW of Spain), one of the most acid rivers on Earth, to assess the chemical association (exchangeable, carbonatic, bound to
manganese and iron oxides, bound to organic matter and residual mineral) of heavy metals (Zn, Cd, Pb, Cu, Cr, Mn, Ni, Fe,
and Hg). Sediments are very heterogeneous in their textural characteristics, showing different grain size. Twenty-seven samples
were studied from from areas along the Odiel River, from the source to the mouth, with special interest in the Odiel Marshes
Natural Park due to its ecological significance. Samples were classified as sandy (especially at the river mouth with low
iron oxide and organic matter content) and clay-silty (in the middle of the river catchment with high iron oxide content).
The numerous sandy samples with low pH values explain the low levels of metals upstream, although potential metals contributions
arise from mining and ore. However, the presence of sulfate in the mining area and carbonate at the mouth may explain the
high presence of lead and iron in these sandy zones. Some percentage of mobile Ni, Cu, and Zn were detected in the mining
area, but the elevated relative percentage of exchangeable Cd in the estuary is even more remarkable. The percentage of Zn
bound to carbonate is considerable in the catchment but especially in the estuary. However, Cu is only detected in the carbonate
phase downstream, in spite of the low concentration of carbonate, which represents a drawback in the application of the Tessier
SES to these types of samples. Finally, relatively high percentages of residual, non-mobile, Hg and Pb were observed, in the
estuarine and mining areas, respectively. Sand, lime, and clay fractions of representative samples from Areas I, II, and III
were used in a metal speciation study. Mainly, the elements analyzed had accumulated in the non-residual fractions. In the
mining area of the Pyrite Belt, the elements analyzed are mainly bound to Fe–Mn oxides (Fe + Mn + Cu + Cr + Pb + Mn ± Zn)
and the organic matter/sulfide fraction (Ni + Zn + Hg ± Cd), independent of sediment grain size. In conclusion, we show that
the results of the study of chemical speciation in sediments from acid rivers are independent of the sediment grain size considered. 相似文献
11.
Iron speciation in interaction with organic matter: Modelling and experimental approach 总被引：1，自引：0，他引：1
The present study aims to model iron speciation when interacting with natural organic matter. Experimental data for iron speciation were achieved with insolubilized humic acid as an organic matter analogue for 1.8 × 10− 3 M and 1.8 × 10− 4 M iron concentrations and 2–5 pH range. Combining EPR spectroscopy and chemical analysis allowed us to fit NICA-Donnan model parameters for both organic complexation of iron and oxides precipitation. 相似文献
12.
Geographical variations of trace elements in sediments of the major rivers in eastern China 总被引：10，自引：0，他引：10
A total of 26 geographically and hydrologically diverse sediment samples were collected from 12 major rivers in eastern China.
The <63-μm fraction of the sediments was analysed for both total concentrations of Cu, Zn, Pb and Cd, and their associations
with various geochemical phases. The geographical variations of sediment-bound trace metals can be related to the bedrock
types and weathering processes in the corresponding river basins. The rivers in southern China had notably higher concentrations
of trace metals in sediments because of abundant non-ferrous mineral deposits and stronger weathering process in the region.
A large proportion of trace metals in these sediments was associated with iron and manganese oxides and organic matter. Relative
low levels of trace metals were found in river sediments in northern China, and a significant proportion of the metals was
bound to organic matter, carbonates, and the residual fraction. The sediments in the Yellow River, originating from special
loess, had the lowest concentrations of trace metals. Most of the trace metals were associated with the carbonates and residual
phases.
Received: 24 March 2000 · Accepted: 11 July 2000 相似文献
13.
The water ecosystem of the Vyshny Volochek Reservoir is characterized based on the study of the distribution of heavy metals speciations in the solid phase and pore waters of bottom sediments. Using the sequential extraction procedure, it is shown that Mn is mainly present in exchangeable and carbonate-bound forms; significant roles for Fe, Zn, Pb, and Co are played by forms that are bound to iron and manganese hydroxides and Cu and Ni are mainly bound to organic matter. Thermodynamic calculations have established the prevailing share of the following forms in pore waters: free ions for Zn, Ni, Co, and Cd, carbonate complexes for Pb, and fulvic complexes for Cu. It has been revealed that the speciation forms of heavy metals in bottom sediments depend on the lithological features and content of organic matter in sediments. 相似文献
14.
Recently, there has been considerable interest in categorizing the availability of plant essential nutrients and selected
transition metals in the soil environment so as to predict their effects on ecosystem health and the efficacy of potential
management practices. Researchers desire to isolate important soil properties, determinant biotic activities and fundamental
pedogenic processes that control biogeochemical cycling and are potentially modifiable for the goal of ecosystem sustainability.
In a relative sense, a significant portion of this scientific effort has been directed towards temperate and tropical forest
ecosystems, with relatively less attention given towards understanding the boreal forest ecosystem. Consequently, an investigation
was undertaken near Thompson, Manitoba, to: (1) determine the extent of weathering of the principal soils, (2) employ a selective-sequential
chemical extraction method to categorize the soil-chemical fractions responsible for nutrient availability, and (3) infer
the importance of selected soil forming processes responsible for soil genesis and nutrient availability. Preliminary findings
suggest that nutrient availability is related to the nutrient concentration in the cation exchange fraction and/or to nutrients
sequestered by the organic fraction. The metals in the manganese, noncrystalline and crystalline iron oxide fractions may
be bound so tightly to these oxides that they are largely unavailable to plants; however, they are largely responsible for
buffering the more labile pools against gradually changing vegetational and climatic conditions.
Received: 31 October 1996 · Accepted: 21 May 1997 相似文献
15.
16.
The long-term impact of irrigation on a Mediterranean sandy soil irrigated with treated wastewater (TWW) since 1980 was evaluated. The main soil properties (CEC, pH, size distribution, exchangeable cations and chloride, hydraulic conductivity) as well as the organic matter and Cu, Cr and Pb speciation in an irrigated soil and a non-irrigated control soil at various soil depths were monitored and compared during a 2 year experiment. In this second part, we focused on Cu, Cr and Pb behaviour in relation with soil organic carbon (SOC). Soil samples were collected every 3 months during 2 years at the depths 0–20, 20–40 and 40–60 cm and were analysed for exchangeable and total metals, organic carbon content, metal sequential extraction and humic substances – Humic Acids (HA), Fulvic Acids (FA) and Non-Humified Fraction (NHF). Long-term irrigation with a domestic treated wastewater (TWW) may be considered safe with regard to trace metal accumulation in soil. Irrigation lowered the HA and NHF fractions of SOC and made the FA fraction more mobile. Cu bound preferentially to the SOC fraction, Cr was found mainly in the reducible fraction and Pb was bound to all fractions indiscriminately. Cu exhibited a high affinity for the HA fraction, while Pb and Cr had a high affinity for the FA fraction, which indicates a greater mobility of the organically-bound Pb and Cr than of the organically-bound Cu. Evaluation of the potential metal mobility has to take into account not only the usual speciation between labile, reducible and oxidisable fractions, but also the nature of the SOC responsible for the oxidisable fraction. 相似文献
17.
Nicolas Perrier Fabrice Colin Tanguy Jaffré Jean-Paul Ambrosi Jérôme Rose Jean-Yves Bottero 《Comptes Rendus Geoscience》2004,336(6):567-577
Nickel speciation in a nickel hyperaccumulating plant (Sebertia acuminata) and its associated soil of southern New Caledonia was studied using various analytical methods. The soil is formed of iron oxides (goethite, hematite), which contain almost all the nickel. The available nickel is probably linked to the organic matter in the litter. Sebertia acuminata, acts as a nickel pump, and concentrates the metal in its leaves. It partitions nickel and silica; nickel is concentrated in the cells (probably in the vacuoles) as organometallic complexes, whereas silica forms the framework of the cells, and the phytolithes. A thorough study of these plants seems essential in order to define the soil–plant relations, and to propose appropriate ways for ecological restoration. To cite this article: N. Perrier et al., C. R. Geoscience 336 (2004). 相似文献
18.
The importance of trace metal scavenging by organic matter in geochemical samples was estimated using an alkaline sodium hypochlorite extraction to leach copper, zinc, molybdenum, iron and manganese from a variety of soils, and stream and lake sediments collected on the Nechako plateau, central British Columbia. The reagent oxidizes or dissolves most forms of organic matter, together with any sulphide minerals, to give strongly coloured extracts containing the associated trace elements at a pH where solution of other sample fractions is at a minimum. Metals precipitated due to alkaline conditions are redissolved by a succeeding distilled-water leach (pH 3.0 ± 0.3).A large fraction of the copper, zinc, molybdenum, and manganese held within the organic fraction of the A soil horizon is liberated whereas only minor amounts of copper, zinc, and manganese are released from inorganic soil (B and C) horizons. Molybdenum, however, is relatively soluble in all soils as the molybdate ion. Despite similar concentrations of organic matter in A horizon soils and stream sediments the latter release a lower proportion of their trace element content. Behaviour of the organic fraction of lake sediments varies from lake to lake and there is great variability in the association of copper, zinc, molybdenum and manganese with organic matter even within the same lake.The presence of organic matter in samples subjected to other partial extractions can be a deleterious factor if the organic fraction is not first removed by a hypochlorite extraction. 相似文献
19.
《Applied Geochemistry》2006,21(10):1781-1798
The metal content of sediments from 4 ponds representative of contrasting environments and design was determined through speciation studies using both sequential chemical extraction and mineralogical observation. Surprisingly, the speciation for a given pond appears to be very homogenous, with the homogeneity being independent of total metal content, particle size or location within the pond. In contrast to what is commonly expected, no increase in metal content was found with decrease in size class. The proportion of metals in the different phases is distinct from one pond to another, reflecting distinct catchment areas. Contributions of alloys and atmospheric particles from industrial processes can be ascertained by SEM. Cadmium showed the highest availability in all 4 ponds with 40–60% extracted during the first step of the Community Bureau of Reference extraction scheme. Zinc, Pb and Cu, mostly sorbed on organic matter or oxides, may also become more mobile depending on physico-chemical changes. In France, an estimated volume of 5 million tons of sediment is extracted annually, and it is obvious that the risk, both environmental and human, associated with its heavy metal content and speciation cannot be totally ignored for the future use of this sediment. 相似文献
20.
煤及其转化产物中重金属形态分布研究 总被引：2，自引：1，他引：1
参考Tessier形态分析程序,对煤及其转化产物中的Mn、Mo和Pb的存在形态进行了实验研究,为原煤使用形态转化中的环境效应评价提供参考。结果表明,Mn、Mo和Pb在原煤、煤焦、气化灰、燃煤灰中的形态变化依次为：可交换态、碳酸盐结合态比例下降,铁锰水合氧化物结合态比例上升;各元素的可交换态和碳酸盐结合态含量之和在原煤、气化灰、燃煤灰中依次减少;对原煤和煤焦中的有机态重金属的重复及高提取剂浓度提取是有效的。 相似文献