Geochemical Behavior of Arsenic in Kelly Lake,Ontario

The objective of this study was to investigate the geochemical behavior of As in Kelly Lake, Ontario. A total of 65 water samples were collected from August 1998 to October 1999. Concentrations of As (total, dissolved and particulate) were determined in each water sample. Thermodynamic models suggest that As interactions with Fe hydroxides could limit As concentrations in Kelly Lake water samples (by adsorption and forming arsenate minerals). It was concluded that Fe(II) arsenates (and not Fe(III) arsenate) formation/dissolution could control As concentrations in Kelly Lake. The activity of As (in terms of HAsO₄ ^2-) in the water samples was calculated from the monitoring data. The calculated activities were superimposed on the thermodynamic model of As minerals. All the calculated activity observations clustered around the Fe₃(AsO₄)₂.8H₂O(c)/Fe₄Fe₂(OH)₁₂. SO₄(c).These observation suggest that the solubility of As in Kelly Lake is controlled by the equilibrium of Fe₃(AsO₄)₂.8H₂O(c)/Fe₄Fe₂(OH)₁₂.SO₄(c), as suggested by thermodynamic solubility isotherms. The As concentration data were limited and spatial trend could not be verified in Kelly Lake water samples, although a decreasing trend in As concentrations at all depths was noticed from June to October 1999.     

Column Studies on Nitrate Removal from Potable Water

Biological processes can achieve nitrate removal from groundwater. The sulfur/limestone autotrophic denitrification by Thiobacillus denitrificans was evaluated with three laboratory-scale column reactors. The optimum sulfur/limestone ratio was determined to be 2:1 (mass/mass). Different hydraulic retention times were used during the column tests to examine nitrate removal efficiencies. Under an HRTs of 13 h, nitrate concentration of 60 mgNO₃ ^--N L^-1 was reduced to less than 5 mg NO₃ ^--N L^-1. On a higher HRT of 26 h the nitrate removal efficiency was close to 100% for all nitrate-nitrogen loading rates. Different initial nitrate-nitrogen concentrations (30, 60, and 90 mg NO₃ ^--N L^-1) were used in the study. Column tests showed that the nitrate-nitrogen loading rate in this study was between 50 to 100 g NO₃ ^--N m^-3 d^-1 to obtain a removal efficiency of 80–100%. It was found that approximately 6 mg SO₄ ^2- was produced for 1 mg NO₃ ^--N removed. Nitrite-nitrogen in all cases was less than the maximum allowable concentration of 1 mg NO₂ ^--N L^-1. Effluent pH was stable in the range of 7 to 8; the effluent dissolved oxygen was less than 0.15 mg L^-1 and the oxidation-reduction potential in all columns was in the range of –110 to –250 mV.     

凉水国家级自然保护区溪流水化学特征分析

 采用集水区对比分析方法,探讨凉水国家级自然保护区不同森林类型对溪流水化学特征的影响。结果表明:保护区内各集水区溪流水均呈弱酸性至中性;主要离子中阳离子均以Ca2+的质量浓度最高,Na+次之,阴离子均以HCO3-的质量浓度最高,SO2-4次之;不同集水区溪流水中TP月平均质量浓度为0.031～0.077mg/L,TN为0.682～0.942 mg/L,NO-3-N的质量浓度高于NH+4-N;Fe的月平均质量浓度为0.030～0.037mg/L,Mn为0.010～0.012 mg/L。溪流水化学季节变化规律表现为:除HCO-3、SO2-4、Ca2+、Fe和Mn外,其他元素在融雪（4、5月）含量均较高;大多数元素在雨季的质量浓度比9月份低,而TN、TP、Fe、Mn表现为9月份的质量浓度低于雨季。保护区内原始阔叶红松林集水区溪流水质为最优,其他研究集水区溪流中的溶解物质含量增高,但除TP和SO2-4（p<0.05）外,差异性均不显著。说明凉水国家级自然保护区内虽进行过森林采伐和人工造林等人为干扰,但对于溪流水质并没有显著影响。     

Interference by organic complexation of Fe and A1 on the SO2-4 adsorption in Spodic B horizons in Sweden

The relations between pH, different fractions of Fe and A1 and Na₄P₂O₇-soluble C and the amount of adsorbed SO^2-₄ were assessed by analysing 63 soil samples from 14 podsolized soils in Sweden. The amount of adsorbed SO^2-₄ was significantly better correlated with the calculated amount of the inorganic fraction of Fe and A1 oxides obtained by subtracting Na₄P₂O₇-soluble Fe and A1 from oxalate-soluble Fe and Al than with the oxalate extraction alone. There was a close correlation between C and organically-bound S in the Na₄P₂O₇ extract which shows that the C:S ratio of the extracted fulvic acids is about constant in the soils studied. It was found that, as the proportion of organically-complexed Fe and Al increases, the ability of the soil to adsorb SO^2-₄ decreases. The amount of adsorbed SO^2-₄ expressed on the basis of the amounts of oxalate-soluble Fe and Al was generally smaller in areas with low S deposition (< 60 mmol m^-2 a^-1). The ratio between pyrophosphate-soluble C and oxalate-extractable Fe and Al was negatively correlated with pH in water. It was concluded that Fe and Al associated with organic matter cannot adsorb SO^2-₄ and that the degree of this association is pH dependent. These observations have important implications regarding the effects of anthropogenic acidification.     

Aluminum speciation in soil solutions: Equilibrium calculations

A computer simulation was done to illustrate how the equilibrium solubility and speciation of Al in well-aerated soil solutions may be affected by pH (from 2.0 to 10.0), organic acids (citric, oxalic, phthalic, and salicylic acid), metal ions (K, Mg, Ca, Al, Fe), inorganic ligands (F, OH, SO₄, PO₄, CO₃, and SiO₃), and type of Al-containing solid [kaolinite, gibbsite, or amorphous Al(OH)₃] thought to be present. The simulation indicated that the type of Al-oxide/hydroxide considered has a substantial influence on the inorganic and organic equilibrium composition of the soil solution, and on the occurrence (or non-occurrence) of other Al-minerals such as KA1₃(SO₄)₂(OH)₆ (alunite) and Al(SO₄)(OH)-5H₂O (jurbanite).     

Heavy Metals in Wastewater: The Effect of Electrolyte Composition on the Precipitation of Cadmium(II) Using Lime and Magnesia

The effect of effluent composition on the efficiency of hydroxide precipitation of Cd(II), using both lime and magnesia as precipitants, has been modelled by the solubility domain approach in order to provide wastewater effluent treatment limits, and has been experimentally validated. Common anionic species such as Cl^?, SO₄ ^2? and CO₃ ^2? have been treated. Solubility domain calculations were based on those phases that were found to determine metal solubility for systems representing the upper and lower limits of potential effluent chemical compositions. The isolated phases were found to resemble their mineralized counterparts, although in several cases exhibited a lower degree of structural order. Experimentally determined Cd(II) solubilities were generally encompassed within the calculated solubility domains, indicating that solubility domain predictions provide effluent treatment quality assurance ranges for the hydroxide precipitation process. The formation of gypsum (CaSO₄.2H₂O) and calcite (CaCO₃) at higher SO₄ ^2? and CO₃ ^2? concentrations as secondary precipitates using lime as the precipitant, and the hydroxy-sulfate Mg₂(OH)₂SO₄.xH₂O, nesquehonite (MgCO₃.4H₂O), hydromagnesite [Mg₅(OH)₂(CO₃)₄.4H₂O] and brucite [Mg(OH)₂] when employing magnesia was shown to have little effect on the observed residual Cd(II) solubility, although Mg(OH)₂ did promote β-Cd(OH)₂ formation in the Mg²⁺-containing Cd(II)/Cl^? and Cd(II)/SO₄ ^2? systems.     

Heavy Metal–Mineral Associations in Coeur d’Alene River Sediments: A Synchrotron-Based Analysis

Nearly a century of mining activities upstream have contaminated Lake Coeur d’Alene and its tributaries with Pb, Zn, and other heavy metals. Heavy metal concentrations in sediments of the Coeur d’Alene watershed have been shown to be inversely proportional to the sediment size fraction; thus, analysis on a very small scale is essential to determine the mobility and stability of heavy metals in this environment. Micron-scale synchrotron-based methods were used to determine the association of heavy metals with solid phases in sediments of the Coeur d’Alene River. Bulk X-ray diffraction (XRD), extended X-ray absorption fine structure spectroscopy, and synchrotron-based microfocused XRD combined with microfocused X-ray fluorescence mapping indicate the presence of crystalline Pb- and Zn-bearing mineral phases of dundasite [Pb₂Al₄(CO₃)₄(OH)₈·3H₂O], coronadite [PbMn₈O₁₆], stolzite [PbWO₄], mattheddleite [Pb₁₀(SiO₄)_3.5(SO₄)₂Cl₂], bindheimite [Pb₂Sb₂O₇], and smithsonite [ZnCO₃]. Likely phases for Zn and Pb adsorption were ferrihydrite, diaspore [AlO(OH)], manganite [Mn^(III)O(OH)], muscovite [KAl₂(Si₃Al)O₁₀(OH,F)₂], biotite [K(Fe,Mg)₃AlSi₃O₁₀(F,OH)₂], and montmorillonite [Na_0.3(Al,Mg)₂Si₄O₁₀(OH)₂·8H₂O]. The large predominance of Fe and Mn (hydr)oxides over other sorbent minerals suggests that the metal sorption behavior is dominated by these (hydr)oxide phases.     

Controlling Acid Drainage in a Pyritic Mine Waste Rock. Part I: Statistical Analysis of Drainage Data

Field experiments were conducted to evaluate the relativeeffectiveness of several covers and amendment techniques forpreventing or controlling acid generation in a pyritic minewaste rock. The covers and techniques consisted of water cover,soil cover, wood bark cover, limestone addition and phosphaterock addition. Water quality data (pH, sulphate, zinc and ironconcentrations) obtained from the experiments were analyzedusing two-way ANOVA (analysis of variance) with repeatedmeasurements. A 5% test of significance (p-value of 0.05) wasused in the analysis. The results suggested that the covers andamendments should be either compared on a time-by-time basis orgrouped into four, based on their performance: (i) water cover, (ii)1% and 3% limestone, (iii) clay, 1% and 3%PO₄, andcontrol (no cover), and (iv) wood bark. The results did not showany significant difference between the drainage quality from1% and 3% limestone-amended rocks. The drainage quality from the 1%and 3% phosphate and clay-covered rocks did not significantlydiffer from the control (unamended) rock. Water cover was foundto be the most effective, while the wood bark cover proved to bean ineffective method for controlling acid drainage in the wasterock. The statistical analysis also showed good replication inthe experiments, as no significant difference in the quality ofthe drainage from the replicates was observed.     

塔里木盆地西南缘典型灌区土壤盐渍化特征分析——以塔吉克阿巴提镇为例

在野外GPS定点定位调查、土壤样品分析的基础上,借助Excel和ArcGIS9.3等软件,对新疆自治区喀什市岳普湖县塔吉克阿巴提镇0-30cm土层的盐离子特征、灌区土壤盐渍化现状及空间分布特征进行了分析。结果表明,0-30cm土层土壤中的离子以Cl^-,SO₄^2-,Na⁺,Ca²⁺为主Na+与Cl^-呈极显著正相关关系,相关系数为0.98,HCO₃^-与其它6种离子(Na⁺,Ca²⁺,Mg²⁺,K⁺,Cl^-,SO₄^2-)呈负相关关系受灌排系统影响较大的农田0-30cm土壤中Cl^-/SO₄^2-比值远小于不受灌排系统影响的荒地农田和荒地0-30cm土壤中的Cl^-/SO₄^2-比值与总盐呈正相关关系,相关系数依次为0.68和0.32。现阶段对塔吉克阿巴提镇灌区农业危害最严重的是氯化物-硫酸盐盐渍化土,硫酸盐盐渍化土表现为盐渍化土地向非盐渍化土地转变的过渡类型非盐渍化农田及轻度盐渍化农田主要分布在开垦较早,灌排系统畅通的区域,灌排系统不畅通的区域仍然处于脱盐缓慢或持续积盐的状态。     

Trends in Water Chemistry of Acidified Bohemian Lakes from 1984 to 1995: II. Trace Elements and Aluminum

The concentrations of Al, Be, Cd, Cu, F, Fe, Mn, Pb, and Zn were monitored in five glacial lakes and one man-made lake in the southwestern part of the Czech Republic. The lakes had median pHs of 4.4 to 6.5 during 1984 to 1995. Decreases in the concentrations of Mn and Pb occurred in five acidified lakes. The concentrations of Al_T, Be, Cd, and F decreased in the four chronically acidified lakes, Zn decreased in two lakes. Concentrations of Cu and Fe remained unchanged. The decreases in Be, Mn, and Zn concentrations were proportional to the decrease in C_SA (C_SA = SO₄ ^2- + NO₃ ^-+ Cl^-); decreases in Al_T, Cd, and Pb concentrations were proportionately higher, while F was lower. The greater decrease in the Pb concentrations (61 to 79%, at a rate up to 0.15 μg L^-1yr^-1) was caused by pronounced decreases in deposition of Pb derived from mobile sources. The decrease of Al_T concentrations was dominated by a decrease in Al³⁺, whose concentration decreased by 51 to 86%. The concentrations of complexes Al(OH)²⁺, Al(OH)₂ ⁺, AlF²⁺, and AlH₃SiO₄ ²⁺ also decreased. The decrease in the concentrations of inorganic forms of Al (Al_i) compensated 65% of the decrease in C_SA. The Cd concentrations were highly variable in the years 1986 to 1988 because of variable amounts of accumulation on particles.     

HYDROCHEMISTRY OF THE AQUIFERS IN THE RIO LAS AVENIDAS BASIN,PACHUCA, HIDALGO,MEXICO

Groundwater in the Rio de las Avenidas sub-basin corresponds to the bicarbonate-sodium and bicarbonate-calcium hydrochemical facies, which result from the mineralization of water passing through alkaline rocks (andesites) which prevail in this basin. However, the presence of high concentrations of Na⁺ and K⁺ reveals the existence of an external inflow of these elements: the registered mean values are respectively 94.3 and 19.0 ppm, with the Tèllez and Tizayuca areas standing out with reported values of up to 142 ppm. As for the concentration of soluble water cations, we find in decreasing order: Na⁺, Ca²⁺, Mg²⁺, K⁺,along with the anions HCO₃ ^-, Cl^-, SO₄ ^2-, CO₃ ^-, which combine to form the NaHCO₃, NaCl, Ca(HCO_{3 2}, MgSO₄ and KCl salts. The presence of biological contaminants, P and detergents in the groundwater indicates that it may have been contaminated by waste water. In addition to the contaminants mentioned above, large quantities of Pb, B, Zn, Fe, Mn, Cr, Co were detected and although Fe, Pb, Zn, B,and Mn are closely related to the local lithology, the high concentrations of these elements along with the occurrence of Co, Cr, Cd, and Ni confirm the gradual degradation of the aquifers in the sub-basin. The water temperature indicates the existence of low temperature thermal processes in the area.     

Amorphous Aluminum Hydroxide Control on Sulfate and Phosphate in Sediment-Solution Systems

We experimentally determined the adsorption characteristics of natural, freshly precipitated Al(OH)₃ for SO₄ and PO₄. The fresh Al precipitate occurred in stream sediment of Jachymov Stream (Czech Republic). The Al-rich sediment strongly adsorbed added PO₄ prior to acidification experiment; this sorbed PO₄ was released only after substantial dissolution of the sediment, at pH?<?3.67. Sorption of P by Al(OH)₃ appears to be an important control on dissolved PO₄ concentration in surface waters, unless there is a large excess of PO₄. Acidification of the sediment-solution system caused protonation of the sediment surface, thereby increasing the adsorption capacity for SO₄. Maximum SO₄ adsorption occurred at pH 4.2, below which dissolution of the sediment offset the increasing anion adsorption capacity, and formation of AISO₄ ⁺ inhibited the increasing SO₄ adsorption capacity. This research demonstrates that there are important pH thresholds for anion adsorption in freshwaters below which dissolution of the Al(OH)₃ substrate reduces total capacity for anion adsorption. In freshwaters, with sufficient concentrations of suspended Al(OH)₃, or in Al(OH)₃-rich sediment, PO₄ mobility will be severely restricted. Suspended Al(OH)₃ in acidified surface waters cannot strongly influence SO₄ concentrations because of the considerably higher total SO₄ concentrations compared to the available surface area.     

A Numerical Approach to Simulate the Biogeochemical Involvement in a Coastal Reduced Groundwater Environment

Bacteria-mediated reduction processes play a decisive role in the water quality alterations in the subsurface environment of coastal aquifers. Availability of organic carbon as the electron donor with other electron acceptors such as NO₃ ^?, MnO₂, Fe(OH)₃ and SO₄ ^2? induces different bacteria to activate under aerobic and anaerobic conditions. A two-dimensional reactive transport model has been developed to simulate the bacteria-mediated reduction reactions in a coastal aquifer. The model explains the utilisation of O₂, NO₃ ^?, MnO₂, Fe(OH)₃ and SO₄ ^2? as electron acceptors for the oxidation of organic carbon in the aquifer under aerobic and anaerobic conditions. The conceptual model consists of three different phases named as bio phase, mobile phase and matrix phase. Model parameters are adopted from literature on bacteria-mediated multi-component modelling and bioremediation processes. Monod kinetic equation is assumed to formulate the bacterial growth. The model explains the behaviours of aerobic and anaerobic bacteria under the availability of organic carbon. Two scenarios are tested and numerical results are discussed. The present numerical study highlights the possibility of the simulation of the formation of reduced environments in coastal aquifers which has not received much attention of groundwater modelling community yet.     

Remediation of Acid Rock Drainage by Regenerable Natural Clinoptilolite

Clinoptilolite is investigated as a possible regenerable sorbent for acid rock drainage based on its adsorption capacity for Zn, adsorption kinetics, effect of pH, and regeneration performance. Adsorption of Zn ions depends on the initial concentration and pH. Adsorption/Desorption of Zn reached 75% of capacity after 1–2 h. Desorption depended on pH, with an optimum range of 2.5 to 4.0. The rank of desorption effectiveness was EDTA?>?NaCl?>?NaNO₃?>?NaOAc?>?NaHCO₃?>?Na₂CO₃?>?NaOH?>?Ca(OH)₂. For cyclic absorption/desorption, adsorption remained satisfactory for six to nine regenerations with EDTA and NaCl, respectively. The crystallinity and morphology of clinoptilolite remained intact following 10 regeneration cycles. Clinoptilolite appears to be promising for ARD leachate treatment, with significant potential advantages relative to current treatment systems.     

Application of “Four-Plane Model” to the Adsorption of K+, NO3 -, and SO4 2- from a Mixed Solution of KNO3 and K2SO4 on Andisols

To evaluate the interaction between anionic species when they were adsorbed on variable charge soils, we measured the adsorption of NO₃ ^- and SO₄ ^2- on. an Andisol equilibrated with a mixture of KNO₃ and K₂SO₄ solutions. The amount of NO₃ ^- adsorption declined with the increase in the concentration of SO₄ ^2-. On the other hand, the amount of SO₄ ^2- adsorption increased with the increase in the concentration of NO₃ ^-. These phenomena can not be explained by the simple “exchange theory” or the “Three-plane model” unless surface complexation is associated with the changes in the electrical potential of the surface. Therefore, in order to explain the phenomena by using the “Four-plane model” with surface complexation, a new equation was derived for the Diffuse Double Layer (DDL) charge from the “main equation of DDL theory” (equation of electrical potential in DDL) instead of the “Gouy-Chapman equation,” which can be used only for single symmetric electrolytes but nor for a mixture. By introducing the new equation to the computer program for analyzing the Four-plane model, the interaction between anionic species adsorbed on Andisols could be explained well. It was considered that SO₄ ^2- acted as a regulator for the ionic concentration, osmotic pressure and pH of the soil solution, and consequently, these factors affected the vertical distribution and mobility of anionic species and also the mobility of counter-ions in Andisols.     

Atmospheric Bronze and Copper Corrosion as an Environmental Indicator. A Study Based on Chemical and Sulphur Isotope Data

Corrosion products have been takenfrom 130 copper or bronze outdoor objects all overEurope. Their chemical composition and crystalsymmetry have been determined by means of scanning electron microscopy (SEM/EDS) and X-ray powderdiffraction. Data on location, sampling, objectcharacteristics, general environment and air pollutionlevel; type, colour and chemical composition of thecorrosion layers have been obtained and evaluated by multivariate statistical analysis. The resultsverify that the highest air pollution levels are usually associated with the occurrence of thick,black or dark grey corrosion layers on copper orbronze objects, preferentially containing soot, ironoxide hydroxides, and antlerite,Cu₃(SO₄)(OH)₄. Pale green corrosionusually contains brochantite,Cu₄(SO₄)(OH)₆, and is rather associatedwith less polluted areas. Atacamite, a copper hydroxide chloride with the chemical formula Cu₂Cl(OH)₃, is preferentially observed in coastal regions.In addition, sulphur isotope analyses have beenperformed on eleven corrosion samples from citycenters. The δ³⁴S values are typically inthe region from +4 to +6‰ relative to the sulphurisotope standard CDT (Canyon Diablo Troilite) with amean value of 4.7±1.2 (1σ), therebyindicating that the sulphur in the corrosion layers,in the form of brochantite or antlerite, mainlyoriginates from a similar source despite geographicvariation, most likely sulphur contained in air pollutants.     

Sulphate Mobilization and Pore Water Chemistry in Relation to Groundwater Hydrology and Summer Drought in two Conifer Swamps on the Canadian Shield

Variations in sulphate (SO₄ ^2-) concentration of porewater and net SO₄ ^2- mobilization were related to differences in water level fluctuations during wet and dry summers in two conifer swamps located in catchments which differed in till depth and seasonality of groundwater flow. Sulphate depletion at the surface and in 20 cm porewater coincided with anoxia and occurred mainly during the summer when water levels were near the peat surface and water flow rates were low in both catchments. There was an inverse relationship between net SO₄ ^2- mobilization and water level elevation relative to the peat surface, explaining variation in SO₄ ^2- dynamics between the swamps during summer drought periods. Aeration of peat to 40 cm and a large net SO₄ ^2- mobilization (10–70 mg SO₄ ^2- m^-2 d^-1) occurred during a dry summer in which the water level dropped to 60 cm below the surface in the swamp receiving ephemeral groundwater inputs from shallow tills within the catchment. This resulted in high SO₄ ^2- concentrations in the surface water and porewater (30–50 mg L^-1), and elevated SO₄ ^2- concentrations remained through the fall and winter. In contrast, within the swamp located in the catchment with greater till depth (> 1 m), continuous groundwater inputs maintained surface saturation during the dry summer, and SO₄ ^2- mobilization and concentrations of SO₄ ^2- in the pore water during the following fall did not increase. Susceptibility to large water table drawdown and mobilization of accumulated SO₄ ^2- is influenced by the occurrence of ephemeral vs. continuous groundwater inputs to valley swamps during dry summer periods in the Canadian Shield landscape. This study reveals that extrapolation of results of SO₄ ^2- cycling from one wetland to another requires knowledge of the hydrogeology of the catchment in which the wetlands are located.     

Co-Ion Effect on Cr3+ Sorption by Amberlyst-15(H+)

Cr³⁺ sorption on strong acid exchanger Amberlyst-15(H⁺) is studied as a function of time and temperature using CrCl₃.6H₂O and [Cr₄(SO₄)₅(OH)₂] solutions. The rate is found to be governed by a mixed diffusion for both the solutions and faster for Cl^1? solution than SO₄ ^2?. The exchange capacities are found to be higher for Cl^1? system than SO₄ ^2?. From the rate constant values, the energies of activation are calculated using the well-known Arrhenius equation. Equilibrium data is explained with the help of the Langmuir equation. The Langmuir parameters are also found to be higher for exchange from the chloride solutions. Various thermodynamic parameters (??H^o, ??S^o, and ??G^o) for Cr³⁺ exchange on the resin are calculated. The ??G^o values are found to be negative while ??H^o and ??S^o are positive for both the Cr³⁺/Cl^1? and Cr³⁺/SO₄ ^2? systems. It is suggested that in case of Cl^1? solutions, the metal is exchanged as Cr³⁺, while in case of SO₄ ^2? solutions, the metal exchanging specie is CrSO₄ ⁺.     

Analysis of sulfur compounds in acid sulfate soils and other recent marine soils

Abstract

A refined scheme for the semi micro chemical analysis of sulfur fractions in soils is presented. Pyrite is analyzed, as iron, after extraction in HNO₃. Non‐pyrite iron is excluded by a pretreatment with HF/H₂SO₄. Water‐soluble sulfate and jarosite [KFe₃(SO₄)₂(OH)₆], the other dominant sulfur fractions in acid sulfate soils, are analyzed turbidimetrically, as sulfate, after successive extractions by EDTA.3Na (water soluble plus exchangeable SO₄) and by hot 4 M HCl (jarosite). These methods are simpler, less bulky and more specific than most existing procedures.

Introduction of elemental sulfur analysis permits estimation of organic sulfur fraction as well. Sums of individual sulfur fractions agree well with separate total sulfur determinations.

The proposed analysis of pyrite permits also distinction of the components Fe₂O₃, FeO and FeS₂ in soils and rocks².     

阴离子对可变电荷土壤吸附铜离子的影响机理

根据NO-3、Cl-和SO24-对可变电荷土壤和恒电荷土壤吸附Cu2+的影响的比较,探讨了阴离子对可变电荷土壤吸附Cu2+的影响机理。结果表明,当3种阴离子的浓度相同时,在SO24-体系中铁质砖红壤对Cu2+的吸附率较在NO3-和Cl-体系中大得多,而在浓度相同的3种阴离子体系中,黄棕壤对Cu2+的吸附率相差不大。在离子强度相近的NaCl体系中,砖红壤对Cu2+的吸附率相近。在3种阴离子体系中,随着pH升高,砖红壤对Cu2+的吸附率均增大;但在NO-3体系和Cl-体系中Cu2+的吸附率相近;而在SO24-体系中Cu2+的吸附率最大。随着Na2SO4浓度的增大,铁质砖红壤和砖红壤对Cu2+的吸附率减小。但在0.005 mol L-1和0.05 mol L-1Na2SO4体系中,Cu2+的吸附率大于在不含Na2SO4的体系中者。而在0.5 mol L-1Na2SO4体系中,Cu2+吸附率小于在不含Na2SO4体系中者。在3种浓度的Na2SO4体系中,黄棕壤对Cu2+的吸附率均小于在不含Na2SO4体系中者。总之,阴离子可通过离子强度、专性吸附和形成离子对影响土壤对Cu2+的吸附。在可变电荷土壤中,阴离子对Cu2+吸附的影响机理较在恒电荷土壤中复杂得多。