作为颗粒运移的示踪剂的土壤7Be, 137Cs, 226Ra和228Ra的地球化学种类

A brunisolic soil collected from an erosive forest land(HF-1-1) and a yellow soil from and accumulative shallow basin(HF-6-1) in the watershed of Lake Hongfeng (HF) were used for activity measurements of ^7Be,^137Cs,^226Ra and ^228Ra in different geochemical speciation.More than 85% of ^7Be,^137Cs,^226Ra and 228Ra in the soils were bound to organic Fe-Mn oxy-hydroxide and residual fractions.They could move with soil particlesw and be used as tracers for the erosion and /or accumulation of soil particles.^7Be gohemical specition in the soils agreed with its trace for seasonal particle transport.^137Cs geohemial speciaiton was suitable for tracing soil particle accumulation and for sediment aating.^226Ra and ^228Ra were ombined in crystalline skeleton of clay minerals and mainly remained as residues in the soils and little was bound to the soluble,exchangeable and carbonate fractions.The differentiation of ^226 Ra/^228Ra activity ratios in different geoheical fractions in the soils could be used as a parameter to trace accumulation and /or erosion of soil particles.     

Distribution of Chemical Forms for Co, Cr, Ni and V in Typical Soils of China

Co,Ni,Cr and V in 25 typical soils of China were fractionated into exchangeable,carbonate bound (calcareous soils),Mn oxide bound,organically bound,amorphous Fe oxide bound,crystalline Fe oxide bound and residual forms using a seven-step sequential extraction procedure,so as to study the distribution of chemical forms of these metals as well as the effects of soil proiperties on the distribution.The results showed that most of soil Co,Ni,Cr and V were present in residual forms,and the distribution ratio averaged 48.2% for Co,53.0% for Ni,81.5% for Cr and 68.7% for V.The speciation of heavy metals was greatly influenced by soil physico-chemical properties and the chemistry of elements.The results also indicated that the recovery of metal elements by the sequential extraction procedure was satisfactory,with the relative difference between the sum of seven forms and the total content in soils averaging 9.5% for Co,12.8% for Ni,6.6% for Cr and 7.2% for V.     

根瘤菌存在下土壤胶体和矿物对镉的吸附

Experiments were conducted to study the adsorption of Cd on two soil collids(red soil and yellowbrown soil) and three variable-charge minerals (goethite,noncrystalline Fe oxide and kaolin) in the absence and presence of rhizobia.The tested strain Rhizobium fredii C6,tolerant to 0.8 mmol L^-1 Cd,was selected from 30 rhizobial strains.Results showed that the isotherms for the adsorption of Cd by examined soil colloids and minerals in the presence of rhizobia could be described by Langmuir equation.Within the range of the numbers of rhizobial cells studied,the amount of Cd adsorbed by each system increased with increasing rhizobial cells,Greater increases for the adsorption of Cd were found in red soil and kaolin systems.Rhizobia influence on the adsorption of Cd by examined soil colloids and minerals was different from that on the adsorption of Cu.The presence of rhizobia increased the adsorption affinity of soil colloids and minerals for Cd,particularly for the goethite and kaolin systems.The discrepancies in the influence of rhizobia on the adsorbability and affinity of selected soil colloids and minerals for Cd suggesed the different interactions of rhizobia with various soil components.It is assumed that bacterial biomass plays an important role in controlling the mobility and bioavailability of Cd in soils with kaolinite and goethite as the major colloidal compnents,such as in variable-charge soil.     

土壤非交换态钾与结构态钾能够区分吗?（英文）

Nonexchangeable K(NEK) is the major portion of the reserve of available K in soil and a primary factor in determining soil K fertility.The questions of how much NEK is in soils and how to quantify total NEK in soils are so far still unclear due to the complicated effects of various minerals on K fixation.In this study,the NEK in 9 soils was extracted with sodium tetraphenylboron(NaBPh_4) for various time periods longer than 1 d.The results showed that the NEK extracted by NaBPh4 gradually increased with time,but showed no more increase after the duration of extraction exceeded 10-20 d.As the temperature increased from 25 to 45 ℃,the duration to obtain the maximum extraction of NEK was reduced from 20 to 10 d,and the maximum values of NEK released at both temperatures was almost the same for each soil.The maximum NEK(MNEK) of the 9 soils extracted by NaBPh.4 varied from3074 to 10081 mg kg~(-1),accounting for 21%-56%of the total soil K.There was no significant correlation between MNEK released by NaBPh4 and other forms of K,such as NH_4OAc-extracted K,HNOg-extracted K and total K in soils,which indicates that NEK is a special form of K that has no inevitable relationship to the other forms of K in soils.The MNEK extraction by NaBPh4 in this study indicated that the total NEK in the soils could be differentiated from soil structural K and quantified with the modified NaBPlu method.The high MNEK in soils made NEK much more important in the role of the plant-available K pool.How to fractionate NEK into different fractions and establish the methods to quantify each NEK fraction according to their bioavailability is of great importance for future research.     

中国土壤学过去30年在一些关键领域的研究进展

Due to continuous decreases in arable land area and continuous population increases,Chinese soil scientists face great challenges in meeting food demands,mitigating adverse environmental impacts,and sustaining or enhancing soil productivity under intensive agriculture.With the aim of promoting the application of soil science knowledge,this paper reviews the achievements of Chinese scientists in soil resource use and management,soil fertility,global change mitigation and soil biology over the last 30 years.During this period,soil resource science has provided essential support for the use and exploitation of Chinese soil resources,and has itself developed through introduction of new theories such as Soil Taxonomy and new technologies such as remote sensing.Soil fertility science has contributed to the alleviation and elimination of impeding physical and chemical factors that constrain availability of essential nutrients and water in soils,the understanding of nutrient cycling in agroecosystems,and the increase in nutrient use efficiency for sustainable crop production.Chinese soil scientists have contributed to the understanding of the cropland’s role in global change,particularly to the understanding of methane and nitrous oxide emission from rice fields and the effect of elevated carbon dioxide and ozone on rice-wheat system.Soil biology research has progressed in biological N fixation,distribution of fauna in Chinese soils,and bioremediation of polluted soils.A new generation of soil scientists has arisen in the last three decades.The gaps between research and application in these soil science fields are also discussed.     

基于微观球体颗粒模型的土水特征曲线研究

When variations occur in the water content or dry bulk density of soil,the contact angle hysteresis will affect the soil-water characteristic curve(SWCC).The occurrence of the contact angle hysteresis can be divided into slipping and pinning.It is difficult to determine the effect of pinning existence on SWCC by tests.In this study,the effect of contact angle hysteresis on SWCC was analyzed either in the case of no variations in soil dry bulk density with changes in soil water content or no variations in soil water content with changes in soil dry bulk density.In both cases,soil particles were simplified to the spherical particle model.Based on the geometrically mechanic relationship between the particles and connecting liquid bridges,a physical model for predicting the SWCC was derived from the spherical particle model.Adjusting parameters made the model applicable to various soils,that is,the cohesive soil was considered as micron-sized spherical particles.Through the simulations on SWCC test data of sand,silt,clay,and swelling soil,it was confirmed that the physical model possessed good reliability and practicability.Finally,the analysis of rationality of contact angle was performed based on the basic assumptions of the model.     

Transformation and Availability of Various Forms of Zinc in Soils

The transformation and availability of various forms of Zn applied into a cinnamon soil and a carbonate meadow soil as well as the effects of fertillizer-P on them were studied by using the field experiment method and chemically sequential extraction procedure.Zn added into the soils was found to be rapidly transformed into the various forms. In the cinnamon soil,the amount of Zn transformed into the carbonate bound form was the highest,and the carbonate bound form was proven by the analyses of intensity factor and capacity factor to be the primary available Zn pool.But in the carbonate meadow soil,the Zn transformed was relatively homogeneously distributed in the various forms though the amount of Zn transformed into the Mn-oxide bound form was relatively high,and the organically bound,Mn-oxide bound and amorphous Fe-oxide,bound forms were found to be the main available Zn pool.Fertilizer-P took part in the regulation and control of available Zn in the soils to a certain degree.In the carbonate meadow soil,application of P fertilizer probably aggravated Zn deficiency at low Zn rate,while it was favorable to the storage of available Zn in the case of high Zn rate.     

一种新的提高树苗盐容量的移植方法

The influence of quinclorac (3,7-dichloroquinoline-8-carboxylic acid) on enzyme activities in flooded paddy soils was assessed under laboratory conditions. The enzymes differed markedly in their response to quinclorac. Quinclorac inhibited proteinase, hydrogen peroxidase, phosphorylase, and urease activities. The higher the concentration of quinclorac applied, the more significant the inhibition to these observed activities with a longer time required to recover to the level of the control. However, soils supplemented with quinclorac were nonpersistent for proteinase~ phosphorylase and urease as opposed to soils without quinclorac. Dehydrogenase activity was also sensitive to quinclorac. Three soil samples with concentrations of quinclorac higher than 1 μg g^-1 soil declined to less than 20% of that in the control. However, the highest dehydrogenase activity (up to 3.28-fold) was detected in soils with 2 μg g^-1 soil quinclorac on the 25th day after treatment. Quinclorac had a relatively mild effect on saccharase activity at the concentrations used in this experiment and a stimulatory one on soil respiration when added to soil at normal field concentrations. Nonetheless it was inhibited at higher concentrations in paddy soils. Quinclorac is still relatively safe to the soil ecosystem when applied at a normal concentration (0.67 μg g^-1 dried soil) but may have some effects on soil enzymes at higher concentrations.     

Temperature sensitivity of soil organic matter decomposition varies with biochar application and soil type

Biochar application has the potential to improve soil fertility and increase soil carbon stock, especially in tropical regions. Information on the temperature sensitivity of carbon dioxide(CO_2) evolution from biochar-amended soils at very high temperatures, as observed for tropical surface soils, is limited but urgently needed for the development of region-specific biochar management targeted to optimize biochar effects on soil functions. Here, we investigated the temperature sensitivity of soil respiration to the addition of different rates of Miscanthus biochar(0, 6.25, 12.5, and 25 Mg ha~(-1)) in two types of soils with contrasting textures. Biochar-amended soil treatments and their controls were incubated at constant temperatures of 20, 30, and 40℃. Overall, our results show that: i) considering data from all treatments and temperatures, the addition of biochar decreased soil CO_2 emissions when compared to untreated soils;ii) CO_2 emissions from biochar-amended soils had a higher temperature sensitivity than those from biochar-free soils; iii) the temperature sensitivity of soil respiration in sandy soils was higher than that in clay soils; and iv) for clay soils, relative increases in soil CO_2 emissions from biochar-amended soils were higher when the temperature increased from 30 to 40℃, while for sandy soils, the highest temperature responses of soil respiration were observed when increasing the temperature from 20 to 30℃. Together, these findings suggest a significantly reduced potential to increase soil organic carbon stocks when Miscanthus biochar is applied to tropical soils at high surface temperatures, which could be counteracted by the soil-and weather-specific timing of biochar application.     

重金属迁移与土壤性质的关系

Cu, Zn, Pb and Hg runoff from yellow limestone soil and purple soils and the relationships between the mobility of the heavy metals and the soil characteristics were studied in laboratory using a rainfall simulator. The results showed that the concentrations of soluble Zn in surface runoff were significantly negatively correlated with the contents of < 0.002 mm particles and CEC of the soils, indicating that Zn was mostly adsorbed by clays in the soils. The contents of Cu and Hg in surface runoff were positively related to their contents in the soils. The amounts of Cu, Zn, Pb and Hg removed by surface runoff were influenced by the amounts of soil and water losses and their contents in the soils, and were closely related to the contents of soil particles 1~0.02 mm in size.     

Soil colloids-bound plasmid DNA: Effect on transformation of E. coli and resistance to DNase I degradation

The adsorption and binding of plasmid p34S DNA on four different colloidal fractions from a Brown soil and clay minerals in the presence of various Ca²⁺ concentrations, the ability of bound DNA to transform competent cells of CaCl₂-treated Escherichia coli, and the resistance of bound DNA to degradation by DNase I were studied. DNA adsorption on soil colloids and clay minerals was promoted in the presence of Ca²⁺. Kaolinite exhibited the highest adsorption affinity for DNA among the examined soil colloids and clay minerals. In comparison with organo-mineral complexes (organic clays) and fine clays (<0.2 μm), DNA was tightly adsorbed by H₂O₂-treated clays (inorganic clays) and coarse clays (0.2-2 μm). The transformation efficiency of bound DNA increased with increasing concentrations of Ca²⁺ at which soil colloid or clay mineral-DNA complexes were formed. DNA bound by kaolinite showed the lowest transformation efficiency, and especially no transformants were observed with kaolinite-DNA complex prepared at 5-100 mM Ca²⁺. Compared to organic clays and fine clays, DNA bound on inorganic clays and coarse clays showed a lower capacity to transform E. coli at different Ca²⁺ concentrations. The presence of soil colloids and minerals provided protection to DNA against degradation by DNase I. Montmorillonite, organic clays and fine clays showed stronger protective effects for DNA than inorganic clays and coarse clays. The protection mechanisms as well as the differences in transforming efficiency of plasmid DNA molecules bound on various soil colloidal particles are discussed. The information obtained in this study is of fundamental significance for the understanding of the horizontal dissemination of recombinant DNA and the fate of extracellular DNA in soil environments.     

Extracellular DNA in soil and sediment: fate and ecological relevance

The review discusses origin, state and function of extracellular DNA in soils and sediments. Extracellular DNA can be released from prokaryotic and eukaryotic cells and can be protected against nuclease degradation by its adsorption on soil colloids and sand particles. Laboratory experiments have shown that DNA adsorbed by colloids and sand particles can be taken up by prokaryotic competent cells and be involved in natural transformation. Most of these experiments have been carried out under artificial conditions with pure DNA molecules and pure adsorbing matrices, but in soils and sediments, pure surface-reactive colloids are not present and DNA is present with other cellular components (wall debris, proteins, lipids, RNA, etc.) especially if released after cell lysis. The presence of inorganic compounds and organic molecules on both soil particles and DNA molecules can influence the DNA adsorption, degradation and transformation of competent cells. Extracellular DNA can be used as C, N and P sources by heterotrophic microorganisms and plays a significant role in bacterial biofilm formation. The nucleotides and nucleosides originated from the degradation of extracellular DNA can be re-assimilated by soil microorganisms. Extracellular DNA in soil can be leached and moved by water through the soil profile by capillarity. In this way, the extracellular DNA secreted by a cell can reach a competent bacterial cell far from the donor cell. Finally, the characterisation of extracellular DNA can integrate information on the composition of the microbial community of soil and sediments obtained by analysing intracellular DNA.     

Distribution of Boron in Different Fractions in Some Alkaline Calcareous Soils

Distribution of boron (B) in different fractions is still not well defined when it is applied in B-deficient alkaline calcareous soil and after harvesting of the sown crop. In the present greenhouse experiment with green gram crop, three B-deficient soils with calcium carbonate contents of 0.8 (S I), 2.1 (S II), and 4.6 (S III) percent were collected from different sites in Ludhiana and Bhatinda Districts, Punjab, India. The treatments composed of five levels of soil-applied B (0, 0.5, 0.75, 1.0, and 1.5 mg B kg^?1) soil and the experiment was laid out in Completely Randomized Design (CRD) factorial design with three replications. Mean readily soluble, specifically adsorbed, and oxide-bound B fractions got increased significantly with increase in B applications. Distribution of readily soluble B was more in low calcareous soil than in high calcareous soil. Mean values of specifically adsorbed, oxide-bound, residual, and total B were significantly more in high calcareous soils as compared to low calcareous soils. At maturity, specifically adsorbed B converted into other fractions to maintain equilibrium in soil solution. Organically bound B was greater than the oxide-bound B fraction. Among all fractions, residual fraction accounted for the major portion of the total B. Available B was negatively and significantly correlated with calcium carbonate (CaCO₃) content of soil (r = ?0.99*). At the same time, specifically bound B was also negatively and significantly correlated with readily soluble B (r = ?0.99*) whereas organically bound B was positively correlated with organic carbon content of soil (r = ?0.99*).     

Speciation of phosphorus in temperate zone forest soils as assessed by combined wet‐chemical fractionation and XANES spectroscopy

Phosphorus availability in terrestrial ecosystems is strongly dependent on soil P speciation. Here we present information on the P speciation of 10 forest soils in Germany developed from different parent materials as assessed by combined wet‐chemical P fractionation and synchrotron‐based X‐ray absorption near‐edge structure (XANES) spectroscopy. Soil P speciation showed clear differences among different parent materials and changed systematically with soil depth. In soils formed from silicate bedrock or loess, Fe‐bound P species (FePO₄, organic and inorganic phosphate adsorbed to Fe oxyhydroxides) and Al‐bound P species (AlPO₄, organic and inorganic phosphate adsorbed to Al oxyhydroxides, Al‐saturated clay minerals and Al‐saturated soil organic matter) were most dominant. In contrast, the P speciation of soils formed from calcareous bedrock was dominated (40–70% of total P) by Ca‐bound organic P, which most likely primarily is inositol hexakisphosphate (IHP) precipitated as Ca₃‐IHP. The second largest portion of total P in all calcareous soils was organic P not bound to Ca, Al, or Fe. The relevance of this P form decreased with soil depth. Additionally, apatite (relevance increasing with depth) and Al‐bound P were present. The most relevant soil properties governing the P speciation of the investigated soils were soil stocks of Fe oxyhydroxides, organic matter, and carbonate. Different types of P speciation in soils on silicate and calcareous parent material suggest different ecosystem P nutrition strategies and biogeochemical P cycling patterns in the respective ecosystems. Our study demonstrates that combined wet‐chemical soil P fractionation and synchrotron‐based XANES spectroscopy provides substantial novel information on the P speciation of forest soils.     

Applicability of rare earth element oxides as a sediment tracer for coarse-textured soils

A leaching experiment using a mixture of five REE oxides and gravelly, sandy loam soils was conducted to examine the applicability of the REE oxides as a sediment tracer for coarse-textured soils. The experiment showed little leaching of the oxides and an enrichment of various size classes of soil particles with the oxides, which reflected the strong binding capability of the REE oxides with the gravelly, sandy loam soils. It also showed that the REE oxides preferentially bound with small size classes of soil particles. The preferential binding of the REE oxides with fine materials will cause the overestimation of the soil loss from a given area (i.e., tagged with a given REE) if aggregates are broken down during sediment transport and clay materials are preferentially delivered, and if the soil loss is computed by analyzing the REE concentrations in the whole sediment. To address the non-uniform binding issue, the method based on measuring the REE concentrations for four particle size groups was tested. The potential error of the method was evaluated by comparing the soil loss that would be computed in the case that the particle size distribution was shifted to the smallest particle size class within a particle size group and in the case that no sediment sorting occurred. The result showed that the method would produce a potential error of approximately 4% in the estimation of the total soil loss when sediment sorting occurred. The non-uniform binding of the oxides does not preclude the use of the REE oxides on the coarse-textured soils in the presence of non-uniform binding of the oxides, but adjustments in the technique are required for an accurate estimation of soil loss using the REE technique.     

Specific surface area and wetting heat of different soil types in European Russia

The surface properties (specific surface area and wetting heat) of the solid phase were estimated for the main soil types of European Russia: soddy-podzolic, alluvial, and gray forest soils; typical, leached, ordinary, and vertic chernozems; and soils of the solonetzic complex. It was found that the values of the specific surface area and wetting heat are indicative of particular features of the genetic horizon of each soil type. Changes in these soil properties under the effect of different anthropogenic impacts were studied. The bonding strength between the adsorbed water and the soil solid phase was characterized. It was shown that the water content at the potential of the first wetting film layer is close to the content of strongly bound water calculated from the wetting heat of the soils.     

Evaluating the fraction of electrically associated cations on surfaces of soil particles by extrapolation of strong-field Wien effect measurements in dilute suspensions

Purpose

For agricultural production and environment protection, it is cations loosely bound to the soil particles that have a great significance in short-term processes of adsorption–desorption, exchange, and transport. It is beneficial to be able to evaluate the fractions of these cations in order to correctly predict potential pollution of soils by heavy metals and availability of plant nutrients.

Materials and methods

The homionic suspensions of yellow-brown soil (YB) and black soil I (BI) saturated with Na⁺ and Ca²⁺ and three subsamples of black soil II (BII) saturated with Ca²⁺ and Cd²⁺ were prepared to determine the electrical conductivity (EC) of the suspensions. On the basis of electrical conductivity vs. field strength (EC-E) curve, the fraction of electrically associated cations on surfaces of soil particles was evaluated by extrapolation of strong-field Wien effect measurements in dilute suspensions.

Results and discussion

The maximum dissociation degree (α _max) of Na⁺ adsorbed on surfaces of yellow-brown soil and black soil I was about 0.21, which is approximately twice as much as those of Ca²⁺ (0.07–0.10) adsorbed on surfaces of two soils. The soil type was not the main factor in evaluating α _max, and the valence of the cations was. For divalent cations, α _max of Ca²⁺ and Cd²⁺ adsorbed on soil particles with different contents of organic matter descended in the order: top black soil II?>?bottom black soil II?>?OM-free bottom black soil II.

Conclusions

The relatively small fractions of electrically adsorbed cations—about 0.2 for Na⁺ and 0.1 for Ca²⁺ on yellow-brown and black soils particles indicated that even for the more loosely adsorbed Na⁺ ions, most of the cations in the double layers of soil particles were adsorbed strongly by other, more specific mechanisms and cannot be stripped off into the solution, which would increase its electrical conductivity in a strong applied field.

     

Adsorption of pure and dirty bacterial DNA on clay minerals and their transformation frequency

Several studies have investigated the adsorption of pure DNA on soil particles and its transformation ability. However, the presence of not purified (dirty) rather than pure DNA is more common in the extracellular soil environment. For this reason, we have investigated the adsorption and binding of dirty DNA on montmorillonite (M) and kaolinite (K) and their transforming ability in comparison to pure DNA. After lysis of Bacillus subtilis cells, induced by KCl, dirty DNA was characterized by the presence of cellular wall debris (cwd) and other constitutional organic components (coc). The dirty DNA was then divided into two fractions, one with cellular wall debris (DNA +cwd) and the other without cellular wall debris (DNA −cwd). B. subtilis BD 1512 (Cm^r) and BD 170 (Cm^s) were selected as donor and recipient bacteria, respectively, for adsorption and transformation studies. Both cwd and coc seem to facilitate the adsorption of DNA to clay minerals, whereas only cwd promote the DNA binding on clays, protecting also the DNA fragments below 400 bp against nucleases. Both dirty DNA fractions adsorbed and bound on clay minerals were able to transform competent cells.     

Assessment of Cadmium Distribution in Some Australian Krasnozems by Sequential Extraction

A sequential extraction procedure was used to investigate the influence of long-term phosphate fertilization on the distribution of cadmium throughout the major components of krasnozemic soils in the potato growing district located to the East of Ballarat, Victoria, Australia. The soil fractions investigated consisted of the water soluble, exchangeable, weakly bound to metal oxides, strongly bound to metal oxides, bound to organic material and residual. Other soil parameters, such as pH_H2O, pH_CaCl2, electrolytical conductivity and total organic material were investigated. The concentrations of Ca, Mg, Fe, Mn and Zn in each soil fraction were also measured. The total concentration of cadmium in the farmed soils had increased from the background level of 100.5 μg/kg to an average of 210 μg/kg. The proportion of cadmium available or potentially available for plant uptake was very low. On average, 89% of the cadmium in the farmed soils had been adsorbed by amorphous metal oxides and organic material, or was associated with silicates, and is therefore unavailable for plant uptake. The metal oxides adsorbed the highest proportion of cadmium.     

PARTITIONING OF HEAVY METALS IN PODZOL SOILS CONTAMINATED BY MINE DRAINAGE WATERS,DALARNA, SWEDEN

The discharge of acidic mine drainage waters onto a hillslope in Dalarna, central Sweden, has lead to the contamination of the podzol soils with Cu, Fe, Ni, Pb, Zn and sulfate. Samples from contaminated and reference soils have been collected for chemical and mineralogical analyses. Jarosite is identified by x-ray diffraction analysis as a precipitate in the upper horizons (A, E, B) of the contaminated soils, where the soil acidity (pH_KCl～2.6) promotes jarosite stability. The sequential chemical extraction of soil samples indicates that, in the reference A horizon, Cu, Pb, Ni and Zn are bound primarily to cation exchange sites and organic matter. In the A horizon of the contaminated soils closest to the rock dump, metal partitioning is dominated by the Fe oxide fractions, despite the high organic matter content; Pb is almost completely bound to crystalline Fe oxides, possibly adsorbed to Fe oxides or occuring in a jarosite solid solution. In the reference B and C horizons, Cu, Ni and Zn are primarily adsorbed/coprecipitated in the Fe oxide fractions, while Pb remains with a large fraction bound to organic matter. In the Fe-rich B horizon of the contaminated soils, the partitioning of the metals in cation exchange sites and to organic matter has greatly increased relative to the reference soils, resulting from the mobilization of organo-metal complexes down the profile.