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.     

在实验酸性硫酸盐条件和酸性硫酸盐土壤上可溶性铝的控制

The controls of soluble Al concentration were examined in three situations of acid sulfate conditions:1) experimental acid sulfate conditions by addition of varying amounts of Al(OH)3(gibbsite) into a sequence of H2SO4 solutions;2)experimental acid sulfate conditions by addition of the same sequence of H2SO4 solutions into two non-cid sulfacte soil samples with known amounts of acid oxalate extractable Al; and 3) actual acid sulfate soil conditions.The experiment using gibbsite as an Al-bearing mineral showed that increase in the concentration of H2SO4 solution increased the soluble Al concentration,accompanied by a decrease i the solution pH, Increasing amount of gibbsite added to the H2SO4 solutions also increased soluble Al concentration,but resulted in an increase in solution pH.Within the H2SO4 concentration range of 0.0005-0.5mol L^-1 and the Al(OH)3 range of 0.01-0.5g(in 25 mL of H2SO4 solutions),the input of H2SO4 had the major control on soluble Al Concentration and pH .The availability of Al(OH)3，however,was responsible for the spread fo the various sample points,with a tendency that the samples containing more gibbsite had a higher soluble Al concentration than those containing less gibbsite at equivalent pH levels.The experimental results from treatment of soil samples with H2SO4 solutions and the analytical results of acid sulfate soils also showed the similar trend.     

Nature of redox concentrations in a sequence of agriculturally developed acid sulfate soils in Thailand

Potential acid sulfate soils (PASS) are drained for agriculture, resulting in the formation of active acid sulfate soils (AASS), which gradually evolve into post-active acid sulfate soils (PAASS). Various redox concentrations (precipitates, costings, and mottles) occur in these soils as a result of pedogenic processes including biological activity and effects of land management. Although several studies have determined the mineralogy and geochemistry of ASS, the mineralogy and geochemistry of redox concentrations occurring in a sequence of ASS through PASS to PAASS have not been investigated. This study examined the mineralogy and geochemistry of redox concentrations and matrices within 5 PASS, 8 AASS, and 5 PAASS in Thailand. The labile minerals were predominantly controlled by oxidation status and management inputs. The unoxidized layers of PASS, AASS, and PAASS contained pyrite and mackinawite. The oxidation of Fe sulfides caused acidification and accumulation of yellow redox concentrations of jarosite and Fe (hydr)oxides at shallow depths. As the soils became well developed, they were recognized as PAASS, and the jarosite and goethite transformed to hematite. As ASS were drained, Co, Mn, Ni, and Zn moved downward and were associated with Fe sulfides and Mn oxides in the unoxided layer. Concentrations of As, Cu, Cr, Fe, and V did not change with depth because these elements became associated with jarosite and Fe (hydr)oxides in yellow and red redox concentrations, as well as the root zone, in the partly oxidized layer of AASS and PAASS. Arsenic was associated with pyrite under reducing conditions.     

集中排水甘蔗地酸性硫酸盐土壤酸化的减缓

Recent research results suggest that acidification of acid sulfate soils may be inhibited in well-drained estuarine floodplains in eastern Australia by the absence of natural creek levees,The lack of natural levees has allowed the inuudation of the land by regular tidal flooding prior to the construction of flood mitigation work.Such physiographical conditions prevent the development of pre-draingae pyrite-derived soil acidifica-tion that possibly occurred at many levee-protected sites in eastern Australian estuarine floodplains during extremely dry spells.Pre-drainage acidification is considered as an important condition for accumulation of soluble Fe and consequently,the creation of favourable environments for catalysed pyrite oxidation.Under current intensively drained onditions,the acid materials produced by ongoing pyrite oxidation can be rapidly removed from soil pore water by lateral leaching and acid buffering,resulting in low concentrations of soluble Fe in the pyritic layer,which could reduce the rate of pyrite oxidation.     

澳大利亚东部地区一些酸性硫酸盐土壤磷的特征

Forty-five acid sulfate topsoil samples (depth < 0.5 m) from 15 soil cores were collected from 11 locations along the New South Wales coast, Australia. There was an overall trend for the concentration of the HC1-extractable P to increase along with increasing amounts of organic C and the HCl-extractable trivalent metals in the topsoils of some less-disturbed acid sulfate soils (pH < 4.5). This suggests that inorganic P in these soils probably accumulated via biological cycling and was retained by complexation with trivalent metals or their oxides and hydroxides. While there was no clear correlation between pH and the water-extractable P, the concentration of the water-extractable P tended to increase with increasing amounts of the HCl-extractable P. This disagrees with some established models which suggest that the concentration of solution P in acid soils is independent of total P and decreases with increasing acidity. The high concentration of sulfate present in acid sulfate soils appeared to affect the chemical behavior of Pin these soil systems. Comparison was made between a less disturbed wetland acid sulfate soil and a more intensively disturbed sugarcane acid sulfate soil. The results show that reclamation of wetland acid sulfate soils for sugarcane production caused a significant decrease in the HCl-extractable P in the topsoil layer as a result of the reduced bio-cycling of phosphorus following sugarcane farming. Simulation experiment shows that addition of hydrated lime had no effects on the immobilization of retained P in an acid sulfate soil sample within a pH range 3.54.6. When the pH was raised to above 4.6, soluble P in the soil extracts had a tendency to increase with increasing pH until the 15th extraction (pH 5.13). This, in combination with the poor pH-soluble P relationship observed from the less-disturbed acid sulfate soils, suggests that soluble P was not clearly pH-dependent in acid sulfate soils with pH < 4.5.     

综述: 酸性硫酸盐土壤的环境风险评价分析方法

Assessment of acid sulfate soil risk is an important step for acid sulfate soil management and its reliability depens very much on the suitability and ccuracy of various analytical methods for estimating sulfide-derived potential acidity,actual acidity and-neutralizing capacity in acid sulfate soils.This paper cirtically reviews various nalytical methods that are currently used for determination of the above parameters,as well as their implications for environmental risk assessment of acid sulfate soils.     

An automated turbidimetric method for total sulfur in plant tissue and sulfate sulfur in soils

Abstract

An automated turbidimetric method has been developed for the rapid and accurate determination of sulfate. The method is practical and useful for accurately measuring total sulfur in plant tissues, and extractable sulfate in soils. The principle of intermittent reagent addition is used which eliminates drift and sensitivity changes caused by coating of BaSO₄ on tubing and cell walls. Also, the appropriate chemistry is used to minimize interactions of the wash with the sample at a sampling rate of 30/H. The sensitivity of the method is excellent with a working range of 0 to 15 ppm sulfur for soils. For plant digests the sample solutions are diluted to 0–35 ppm S. The precision as determined by repeated analysis of a soil sample extract was 0.58% RSD with a mean of 9.26 pg/g extractable SO⁼ ₄‐S. On another soil sample using a different extractant and extraction procedure the RSD was 0.64%, mean of 9.26 μg/g. Multiple automated sulfur analyses on a plant tissue digest resulted in an RSD of 0.41% for a sample containing 0.21% S. The automated turbidimetric method for sulfate has excellent precision and sensitivity in plant tissue and soil analyses where gravimetric BaSO₄ assays are not practical.     

澳洲东部三种沿海漫滩酸性硫酸盐土壤中铁一硫化物的分布

The distribution of iron monosulifde (quantified as acid volatile sulfur:SAV) was compared with geochemical properties that are known to affect its formation and accumulation in three coastal Holocene acid sulfate soils (ASS) at Tuckean Swamp,Mc Leods Creek and Bungawalbyn Swamp respectively,These properties included pH,reactive iron(FeR),pore-water sulfate(SO4^2-) and organic carbon(OC).Iron monosulfide was concentrated at the oxic/anoxic boundary,the Tuckean Swamp and McLeods Creek sites are Holocene sediments,whereas the Bungawalbyn Swamp is a Holocene peat.The concentration of SAV averaged 0.2 g kg^-1 in a 0.5m thick soil layer at the Tuckean Swamp,but was an order of magnitude lower in the oxic/anoxic transition layers at McLeods Creek and Bungawalbyn Swamp,The SAV mineral greigite(Fe3S4) was identified in the Tuckean Swamp by X-ray diffraction and scanning electron microscopy with quantitative energy dispersive X-ray analysis(SEM-EDX),Very small concentrations of greigite were also observed in the McLeods Creek,based on crystal morphology and elemental composition.The concentration of SAV was a small fraction of the total reduced sulfur,representing at most 3% of the pyrite sulfur,However,the presence of this highly reactive sulfide mineral,distributed within pores where oxygen diffusion is most rapid,has important implications to the potential rate of acid production from these sediments.     

Mineralization of organic sulfur and its importance as a reservoir of plant-available sulfur in upland soils of north China

 An open incubation technique was used to measure S mineralization in a range of upland soils of north China. Six mineralization patterns were examined, and a soil S-exhaustion experiment with ryegrass (Lolium multiflorum L.) was conducted to investigate the availability of various organic S pools to plants. For all of the 12 soils tested, the release of S as SO₄ ^2– was curvilinear with time, and during a 28-week incubation at 30  °C the amount of S mineralized ranged from 14.0 mg S kg^–1 soil to 37.4 mg S kg^–1 soil. A first-order model and Gompertz model appeared to best describe S mineralization. Examination of the soils after incubation revealed the bulk of the mineralized S was mainly derived from the C-bonded S pool, while the majority of mineralized S under soil S exhaustion by ryegrass was derived from the HI-reducible S pool. Received: 9 July 1998     

Isolation and characterization of potassium solubilizing bacteria in some Iranian soils

The ability of a few soil bacteria to transform unavailable forms of potassium (K) to an available form is an important feature in plant growth-promoting bacteria for increasing plant yields of high-K-demand crops. In this research, isolation, screening, and characterization of six isolates of K solubilizing bacteria (KSB) from some Iranian soils were carried out. The ability of all isolates were tested in three treatments including acid-leached soil, biotite, and muscovite by analyzing the soluble K content after 5 days of incubation at 28 ± 2°C. Identification and phylogenetic analyses were also carried out by morphological, biochemical, and 16S rDNA analyses. Among the six efficient isolates, five isolates belonged to Bacillus megaterium (JK3, JK4, JK5, JK6, and JK7), while isolate JK2 belonged to Arthrobacter sp. The soluble K contents in all isolated-treatments were significantly (p < 0.01) higher than the contents in nonbacteria treatment. Herein, isolate JK2 had lower potential for K solubilization (910 mg kg^?1) compared with other isolates in acid-leached soils. The six bacterial strains showed higher solubilized K in biotite treatment than other two treatments. Overall, it can be concluded that the isolates belong to B. megaterium are the most efficient KSB under in vitro condition.     

Buffer Ph methods for estimation of lime requirement of tropical acid soils

Abstract

Lime requirements (LR) of 26 agricultural acid soils were estimated using the following buffer methods: Shoemaker‐McLean‐Pratt (SMP) single buffer (SMP‐SB), SMP double buffer (SMP‐DB), Mehlich buffer method for crops with high LR (MEHLICH I), and Mehlich buffer methods for crops with low LR (MEHLICH II). The LR were determined to three pH targets (6.5, 6.0 and 5.5). The LR values were then evaluated through regression analysis using LR values obtained by the Ca(OH)₂ titration (for the 6.5 pH target) and moist CaCO₃‐incubation (for the 6.0 and 5.5 pH targets) as reference methods. All the buffer methods were well correlated with the reference methods but the SMP‐DB gave the best results for both high and low LR soils, and was particularly impressive at the lowest pH target.     

Clay mineralogical and ammonium fixation characteristics of some tropical upland rice soils

Abstract

In view of the agronomic and economic significance of NH₄ fixation in soils, an attempt has been made to relate this to the most reactive mineral constituents of soils ‐ the clay minerals, under the temperature‐moisture regimes normal to tropical upland rice soils. Laboratory fixation study was done with NH₄, concentrations similar to those common in soils upon N fertilization, and under alternate wetting and drying at ambient temperatures rather than at 100°C as in many published studies.

Results of the investigation show that soil clays with dominant vermiculite and montmorillonite fix the greatest proportion of applied NH₄ (94 and 91%), followed by beidellite (72%) and x‐ray amorphous (45–64%) clays. Fixation is negligible (10%) in the clay with mineral suite consisting of hydrous mica, halloysite, and chlorite. Crystallinity of minerals seems to influence NH₄ fixation appreciably.     

Comparing the effects of paper pulp and lime additions to acid tropical soils using batch experiments

Paper mill residuals may beneficially be used to improve the fertility of tropical acid soils. The effects of paper pulp on soil pH, exchangeable Al and soil solution composition of three acid tropical soils were compared with the effects of equivalent rates of lime in two batch experiments. Paper pulp was more effective than lime in increasing soil pH. However, both amendments were equally effective in decreasing exchangeable Al. Paper pulp and lime similarly influenced the composition of the soil solution by increasing soil solution pH, dissolved organic carbon, inorganic carbon, NO₃, SO₄, Ca and Mg. The supply of nitrate by the soil, however, was reduced in paper pulp treatments compared to lime treatments. Nitrate had a major role in controlling nutrient concentrations in the soil solution. Reduced NO₃ concentrations in paper pulp treated soils compared to limed soils could therefore result in lower nutrient availability and limited losses by leaching.     

Organic sulfur forms in mineral top soils of the Marsh in Schleswig‐Holstein,Northern Germany

Little is known about the nature of organic sulfur (S) in soils of the Marsh in Schleswig‐Holstein, Northern Germany. In addition to total and inorganic S, we determined two organic S fractions (ester sulfate‐sulfur and carbon‐bonded sulfur) in 14 aerated mineral top horizons of two salt marshes and ten dyked polder soils of different age. All soils developed from marine sediments. Total S concen‐trations ranged from 153 to 950 mg kg^—1. Organic S was the main S constituent (range from 53 to 99% with a median of 97%). Higher inorganic S levels were found only in the salt marshes due to soluble sulfate (15 to 47%). The younger marsh soils (salt marshes and soils of a polder dyked in 1978) had unique high S contents of 0.9 to 2.4% in their organic matter, whereas the S contents of the organic matter in older marsh soils were at only 0.6%. This S‐rich organic matter is a heritage of a former anoxic marine environment. In most horizons the carbon‐bonded S was the dominant sulfur form. However, both carbon‐bonded S and ester sulfate‐S did not relate to soil age. This limits the benefit of the wet chemical fractionation procedure used for studying the fate of organic S in marsh soils.     

中国四省未开垦表土硫源识别研究

The analysis of stable isotopes of sulfur(δ34S) is a useful tool for identifying sources of sulfur in soils. Concentrations and sulfur(S)isotopes of water-soluble sulfate(WSS), adsorbed sulfate(AS), residual sulfur(RS), and total sulfur(TS) in uncultivated surface soils of four Chinese provinces were systematically analyzed for identifying sources of S in the soils. Green and healthy mosses(Haplocladium microphyllum) were sampled as bioindicators. The mean WSS concentration(27.8 ± 23.4 mg kg-1) in the surface soils was lower than those of AS(101.4 ± 57.0 mg kg-1) and RS(381.5 ± 256.7 mg kg-1). The mean δ34S values of WSS and AS were very similar(about2.0‰), lower than those of RS(8.0‰) and TS(6.1‰). A significant linear correlation was found between the δ34S values of AS and WWS(y = 1.0002x- 0.0557, P 0.0001), indicating that sulfate adsorption in the soils did not markedly fractionate S. All S species in the soils of Guizhou Province were characterized by the lowest δ34S values, consistent with the most34S-depleted rainwater sulfate reported at Guiyang of Guizhou Province. The δ34S values of sulfate in mosses and rainwater previously reported were significantly linearly correlated with those of both WWS and AS in surface soils, suggesting that atmospheric S input was an important source for soil WSS and AS. However, there were no significant correlations between isotopic composition of rainwater sulfate and RS or TS.The slopes of all these significant linear correlations(soil/rainwater or soil/moss isotopic ratio) were 0.4–0.6, indicating that inorganic sulfate in the surface soils should be a result of mixing of deposited atmospheric sulfate with a more34S-depleted sulfate component possibly from mineralization of RS.     

Short‐term potassium release and fixation in some calcareous soils

Potassium (K⁺) directly released from primary K‐bearing minerals can contribute to plant nutrition. The objective of this research was to assess short‐term K⁺ release and fixation on a range of intensively cropped calcareous soils. Potassium sorption and desorption properties and the contributions of exchangeable‐K⁺ (EK) and nonexchangeable‐K⁺ (NEK) pools to K⁺ dynamics of the soil‐solution system was measured using a modified quantity‐to‐intensity (Q : I) experiment. Release and fixation of K⁺ were varied among soils. The relation between the change in the amount of NEK during the experiment and the initial constrain was linear, and soil ability for K⁺ release and fixation (β) for all soils varied from 0.041 to 0.183, indicating that 4% to 18% of added K⁺ converted to NEK when fixation occurred. The equilibrium potential buffering capacity (PBC) for K⁺ derived from Q : I experiments had significant correlation (r = 0.75, p < 0.01) with β, indicating that PBC depends not only on exchange properties but also on release and fixation properties. The depleted soils showed higher β value than the other soils, indicating much of the added K⁺ was converted to NEK in case of positive constraint. The range of the amount of EK which was not in exchange equilibrium with Ca (E_min) in the experimental conditions was large and varied from 0.68 to 9.00 mmol kg^–1. On average, E_min amounted to 64% of EK. This fraction of EK may not be available to the plant. The parameters obtained from these short‐term K⁺ release and fixation experiments can be used in plant nutrition.     

The effect of elemental sulfur,gypsum and ammonium thiosulfate as sulfur sources on yield of rapeseed

Abstract

A growth chamber experiment was conducted to compare ammonium thiosulfate, gypsum and elemental sulfur in the form of Agrisul as sources of sulfur for rapeseed (Brassica napus var. Regent). Rapeseed supplied with ammonium thiosulfate or gypsum produced significantly higher yields than treatments supplied with elemental sulfur. Powdering and mixing of elemental sulfur, as opposed to banding granules, significantly increased dry matter yield of rapeseed. While not always significant, there was a trend towards higher dry matter yields where gypsum granules were mixed as opposed to banded and where ammonium thiosulfate was placed in a band as opposed to being mixed throughout the soil.     

Sulfur speciation in well‐aerated and wetland soils in a forested catchment assessed by sulfur K‐edge X‐ray absorption near‐edge spectroscopy (XANES)

In forested catchments, retention and remobilization of S in soils and wetlands regulate soil and water acidification. The prediction of long‐term S budgets of forest ecosystems under changing environmental conditions requires a precise quantification of all relevant soil S pools, comprising S species with different remobilization potential. In this study, the S speciation in topsoil horizons of a soil toposequence with different groundwater influence and oxygen availability was assessed by synchrotron‐based X‐ray absorption near‐edge spectroscopy (XANES). Our investigation was conducted on organic (O, H) and mineral topsoil (A, AE) horizons of a Cambisol–Stagnosol–Histosol catena. We studied the influence of topography (i.e., degree of groundwater influence) and oxygen availability on the S speciation. Soil sampling and pretreatment were conducted under anoxic conditions. With increasing groundwater influence and decreasing oxygen availability in the sequence Cambisol–Stagnosol–Histosol, the C : S ratio in the humic topsoil decreased, indicating an enrichment of soil organic matter in S. Moreover, the contribution of reduced S species (inorganic and organic sulfides, thiols) increased systematically at the expense of intermediate S species (sulfoxide, sulfite, sulfone, sulfonate) and oxidized S species (ester sulfate, SO ). These results support the concept of different S‐retention processes for soils with different oxygen availability. Sulfur contents and speciation in two water‐logged Histosols subject to permanently anoxic and temporarily oxic conditions, respectively, were very different. In the anoxic Histosol, reduced S accounted for 57% to 67% of total S; in the temporarily oxic Histosol, reduced S was only 43% to 54% of total S. Again, the extent of S accumulation and the contribution of reduced S forms to total S closely reflected the degree of O₂ availability. Our study shows that XANES is a powerful tool to elucidate key patterns of the biogeochemical S cycling in oxic and anoxic soil environments. In contrast to traditional wet‐chemical methods, it particularly allows to distinguish organic S compounds in much more detail. It can be used to elucidate microbial S‐metabolism pathways in soils with different oxygen availability by combining soil inventories and repeated analyses of a sample in different stages of field or laboratory incubation experiments under controlled boundary conditions and also to study (sub)microspatial patterns of S speciation in aggregated soils.     

Boron adsorption and desorption in some acid soils of West Bengal,India

Laboratory and greenhouse experiments were conducted to determine the influence of soil properties on adsorption and desorption of boron (B) as well as to estimate the degree of reversibility of adsorption reactions. The utility of Freundlich and Langmuir equations for characterizing the plant availability of applied B in soils was established using soybean [Glycine max (L.) Merr.] as a test crop. The adsorption-desorption study revealed that Fe₂O₃ and clay were primarily responsible for retaining added B in all the 25 different soils under investigation. Organic carbon, pH and cation exchange capacity (CEC) positively influenced the adsorption of B while free Fe₂O₃, organic carbon and clay retarded release of B from these soils. The degree of irreversibility (hysteresis) of B adsorption/desorption increased with increase in organic carbon and CEC of these soils. Freundlich isotherm proved more effective in describing B adsorption in soils as compared to Langmuir equation. The split Langmuir isotherm demonstrated that any of the adsorption maxima, calculated from lower, upper or entire isotherm, could be of practical use. Contrary, bonding energy coefficient, calculated either at lower or higher equilibrium concentration failed to show any practical benefit. Regression models as a function of B application rate and adsorption equation parameters to predict B uptake from applied B, demonstrated the utility of Langmuir and Freundlich equation parameters.     

Availability and plant uptake of nutrients following the application of paper pulp and lime to tropical acid soils

Availability and plant uptake of nutrients were evaluated in three tropical acid soils (Kandiudult) amended with paper pulp and lime under greenhouse conditions. Amendments were applied to attain target pH values of 5.5, 6.0, and 6.5. A control treatment (no paper pulp or lime added) was also included. Rye grass (Lolium perenne L.) as a test plant was grown for three successive cycles of 40 days each. Extractable nutrients and cumulative nutrient uptake were determined. The application of paper pulp or lime resulted in a significant increase in exchangeable Ca and K and a decrease in exchangeable Mg and extractable Fe, Mn, and Zn. Amendment of soils with paper pulp or lime increased plant uptake of Ca and Mg and decreased that of K, Mn, and Zn. Both amendments behaved similarly, but the effect of lime seemed generally greater than that of paper pulp. Paper pulp in tropical acid soils behaved as a liming agent rather than an organic amendment. Similar to lime, amendment of soils with paper pulp resulted in an increase in availability of Ca and Mg and in a decrease in availability of K, Mn, and Zn for plants. Soil extractions appeared to be appropriate for assessing the availability of Ca, Mn, and Zn. Soil pH and effective cation exchange capacity positively influenced the availability of Ca and negatively the availability of Mn and Zn. Thus, the precision of predicting nutrient availability in paper pulp amended tropical acid soils could be improved by including soil pH or effective cation exchange capacity in relevant regression equations.