The measurement of actual acidity in acid sulfate soils and the determination of sulfidic acidity in suspension after peroxide oxidation

Soil Research ◽  
2002 ◽  
Vol 40 (7) ◽  
pp. 1133 ◽  
Author(s):  
Angus E. McElnea ◽  
Col R. Ahern ◽  
Neal W. Menzies
Keyword(s):  
Regression Line ◽  
Correction Factors ◽  
Acid Sulfate Soils ◽  
Peroxide Oxidation ◽  
Acid Sulfate ◽  
Inorganic Sulfur ◽  
Actual Acidity ◽  
Sulfate Soils ◽  
The Relationship

Improvements to the routine methods for the determination of actual acidity in suspension for acid sulfate soils (ASS) are introduced. The titratable sulfidic acidity (TSA) results using an improved peroxide-based method were compared with the theoretical acidity predicted by the chromium reducible sulfur method for 9 acid sulfate soils. The regression between these 2 measures of sulfidic acidity was highly significant, the slope of the regression line not significantly different from unity (P = 0.05) and the intercept not significantly different from zero. This contrasts with results of other workers using earlier peroxide oxidation methods, where TSA substantially underestimated the theoretical acidity predicted by reduced inorganic sulfur analysis. Comparison was made between the 2 principal measurements from the improved peroxide method (TSA and SPOS), with SPOS converted to theoretical sulfidic acidity to allow comparison. The relationship between these 2 measurements was highly significant. The effects of titration in suspension, as well as raising titration end points to pH 6.5, were investigated, principally with respect to the titratable actual acidity (TAA) result. TAA results obtained by KCl extraction were compared with those obtained using BaCl2, MgCl2, and water extraction. TAA in 1 M KCl suspensions titrated to pH 6.5 agreed well with titratable actual acidity measured using the 25-h extraction approach of the Lin et al. (2000a) BaCl2 method. Both BaCl2 and KCl solutions were ineffective at fully recovering acidity from synthetic jarosite without repeated extraction and titration. The application of correction factors for the estimation of total actual acidity in ASS is not supported by the results of this investigation. Acid sulfate soils that contain substantial quantities of jarosite or other acid-producing but relatively insoluble sulfate minerals continue to prove problematic to chemically analyse; however, an approach for estimating this component is discussed.

Acidity fractions in acid sulfate soils and sediments: contributions of schwertmannite and jarosite

Soil Research ◽  
2013 ◽  
Vol 51 (3) ◽  
pp. 203 ◽  
Author(s):  
Chamindra L. Vithana ◽  
Leigh A. Sullivan ◽  
Richard T. Bush ◽  
Edward D. Burton
Keyword(s):  
Correction Factor ◽  
Soil Samples ◽  
Acid Sulfate Soils ◽  
Peroxide Oxidation ◽  
Acid Base ◽  
Acid Sulfate ◽  
Soils And Sediments ◽  
Actual Acidity ◽  
Sulfate Soils

In Australia, the assessment of acidity hazard in acid sulfate soils requires the estimation of operationally defined acidity fractions such as actual acidity, potential sulfidic acidity, and retained acidity. Acid–base accounting approaches in Australia use these acidity fractions to estimate the net acidity of acid sulfate soils materials. Retained acidity is the acidity stored in the secondary Fe/Al hydroxy sulfate minerals, such as jarosite, natrojarosite, schwertmannite, and basaluminite. Retained acidity is usually measured as either net acid-soluble sulfur (SNAS) or residual acid soluble sulfur (SRAS). In the present study, contributions of schwertmannite and jarosite to the retained acidity, actual acidity, and potential sulfidic acidity fractions were systematically evaluated using SNAS and SRAS techniques. The data show that schwertmannite contributed considerably to the actual acidity fraction and that it does not contribute solely to the retained acidity fraction as has been previously conceptualised. As a consequence, SNAS values greatly underestimated the schwertmannite content. For soil samples in which jarosite is the only mineral present, a better estimate of the added jarosite content can be obtained by using a correction factor of 2 to SNAS values to account for the observed 50–60% recovery. Further work on a broader range of jarosite samples is needed to determine whether this correction factor has broad applicability. The SRAS was unable to reliably quantify either the schwertmannite or the jarosite content and, therefore, is not suitable for quantification of the retained acidity fraction. Potential sulfidic acidity in acid sulfate soils is conceptually derived from reduced inorganic sulfur minerals and has been estimated by the peroxide oxidation approach, which is used to derive the SRAS values. However, both schwertmannite and jarosite contributed to the peroxide-oxidisable sulfur fraction, implying a major potential interference by those two minerals to the determination of potential sulfidic acidity in acid sulfate soils through the peroxide oxidation approach.

Improvements to peroxide oxidation methods for analysing sulfur in acid sulfate soils

Soil Research ◽  
2002 ◽  
Vol 40 (7) ◽  
pp. 1115 ◽  
Author(s):  
Angus E. McElnea ◽  
Col R. Ahern ◽  
Neal W. Menzies
Keyword(s):  
Decision Making ◽  
Analytical Method ◽  
Regression Line ◽  
Organic Soils ◽  
Informed Decision Making ◽  
Acid Sulfate Soils ◽  
Peroxide Oxidation ◽  
Improved Method ◽  
Acid Sulfate ◽  
Sulfate Soils

Improvements to peroxide oxidation methods for analysing acid sulfate soils (ASS) are introduced. The soil solution ratio has been increased to 1 : 40, titrations are performed in suspension, and the duration of the peroxide digest stage is substantially shortened. For 9 acid sulfate soils, the peroxide oxidisable sulfur value obtained using the improved method was compared with the reduced inorganic sulfur result obtained using the chromium reducible sulfur method. Their regression was highly significant, the slope of the regression line was not significantly different (P = 0.05) from unity, and the intercept not significantly different from zero. A complete sulfur budget for the improved method showed there was no loss of sulfur as has been reported for earlier peroxide oxidation techniques. When soils were very finely ground, efficient oxidation of sulfides was achieved, despite the milder digestion conditions. Highly sulfidic and organic soils were shown to be the most difficult to analyse using either the improved method or the chromium method. No single analytical method can be universally applied to all ASS, rather a suite of methods is necessary for a thorough understanding of many ASS. The improved peroxide method, in combination with the chromium method and the 4 M HCl extraction, form a sound platform for informed decision making on the management of acid sulfate soils.

An improved analytical procedure for determination of total actual acidity (TAA) in acid sulfate soils

2000 ◽  
Vol 262 (1-2) ◽  
pp. 57-61 ◽  
Author(s):  
C. Lin ◽  
K. O’Brien ◽  
G. Lancaster ◽  
L.A. Sullivan ◽  
D. McConchie
Keyword(s):  
Analytical Procedure ◽  
Acid Sulfate Soils ◽  
Acid Sulfate ◽  
Actual Acidity ◽  
Sulfate Soils

Comparison of peroxide-oxidisable sulfur and chromium- reducible sulfur methods for determination of reduced inorganic sulfur in soil

Soil Research ◽  
1999 ◽  
Vol 37 (2) ◽  
pp. 255 ◽  
Author(s):  
L. A. Sullivan ◽  
R. T. Bush ◽  
D. McConchie ◽  
G. Lancaster ◽  
P. G. Haskins ◽  
...  
Keyword(s):  
Hydrogen Peroxide ◽  
Organic Matter ◽  
False Negative ◽  
Acid Sulfate Soils ◽  
Acid Sulfate ◽  
Inorganic Sulfur ◽  
Rational Management ◽  
Sulfate Soils ◽  
Significant Interference

The rational management of acid sulfate soils requires analytical methods that provide reliable and accurate data on the content of reduced inorganic sulfur; it is this fraction that produces acid during oxidation. This study compared the utility of the chromium-reducible sulfur method for determining the reduced inorganic sulfur content of soil materials with methods based on oxidation using hydrogen peroxide. The results presented here indicate that methods involving oxidation by hydrogen peroxide for the determination of reduced inorganic sulfur are subject to significant interference by even minor amounts of sulfate minerals and organic matter, resulting in inaccurate determinations of reduced inorganic sulfur contents. In the presence of even minor amounts of gypsum, methods involving oxidation using hydrogen peroxide underestimated reduced inorganic sulfur contents by up to 0·167% sulfur, whereas in the presence of organic matter these methods overestimated reduced inorganic sulfur contents by up to 0·077% sulfur per cent organic carbon. The resulting errors in the determinations of reduced inorganic sulfur by hydrogen peroxide methods were often larger than the action criteria that are currently used to identify acid sulfate soils. Consequently, there is a risk of misidentification of acid sulfate soils (either false positive or false negative) for soils with low reduced inorganic sulfur contents when hydrogen peroxide methods are used. In contrast, the results from the chromium-reducible sulfur method do not appear to be affected by interferences from either gypsum or organic matter and this method appears to be more suitable for the determination of reduced inorganic sulfur in soils than methods based on oxidation using hydrogen peroxide.

Oxidation rate of pyrite in acid sulfate soils: in situ measurements and modelling

Soil Research ◽  
2004 ◽  
Vol 42 (6) ◽  
pp. 499 ◽  
Author(s):  
F. J. Cook ◽  
S. K. Dobos ◽  
G. D. Carlin ◽  
G. E. Millar
Keyword(s):  
Oxidation Rate ◽  
Volume Ratio ◽  
Soil Surface ◽  
Biological Processes ◽  
Acid Sulfate Soils ◽  
Acid Sulfate ◽  
The Difference ◽  
Actual Acidity ◽  
Sulfate Soils

The generation of acidity from oxidation of pyrite in acid sulfate soils requires the transport of oxygen into the soil profile. The sink for this oxygen will not only be the chemical reaction with pyrite but the biological processes associated with both microbial and plant respiration. The biological sinks in burning the oxygen (O2) will release CO2. The respiratory quotient which is the molar volume ratio of O2 : CO2 varies between 1.3 and 0.7 depending on the source of the organic matter being oxidised, but is generally 1.0. The oxidation of pyrite by oxygen will, by comparison with the biological processes, produce minor amounts of CO2 (if any) by reaction with intrinsic carbonate minerals. Gas samplers were installed into the soil at various depths and samples collected from these at approximately fortnightly intervals. The samples were analysed by gas chromatography and the CO2 and O2 profiles obtained. The flux of these gases was calculated and the difference between these attributed to the oxidation of pyrite. The flux difference varied over the period of sampling and on average gave an in situ oxidation rate of 11.5 tonnes H2SO4/ha.year. This is considerably more that the rate of export of acidity from this site and would explain the considerable actual acidity storage in these soils. A model is developed for steady state transport of oxygen into soils with an exponentially decreasing biological sink with depth and an exponentially increasing chemical (pyrite) sink with depth. The model is developed in non-dimensional variables, which allows the relative strengths and rates of increase or decrease in sink terms to be explored. This model does not explicitly treat the flow of oxygen in macropores. Other models that do explicitly calculate macropore flow are compared and found to give similar results. These results suggest that the use of biological or other sinks near the soil surface could be a useful method for reducing the oxidation rate of pyrite in acid sulfate soils.

Soil chemistry and acidification risk of acid sulfate soils on a temperate estuarine floodplain in southern Australia

Soil Research ◽  
2016 ◽  
Vol 54 (7) ◽  
pp. 787 ◽  
Author(s):  
C. C. Yau ◽  
V. N. L. Wong ◽  
D. M. Kennedy
Keyword(s):  
Soil Chemistry ◽  
Acid Sulfate Soils ◽  
Shell Material ◽  
Acid Sulfate ◽  
Estuarine Processes ◽  
Acid Neutralising Capacity ◽  
Eastern Australia ◽  
Actual Acidity ◽  
Sulfate Soils ◽  
Soil And Water

The distribution and geochemical characterisation of coastal acid sulfate soils (CASS) in Victoria in southern Australia is relatively poorly understood. This study investigated and characterised CASS and sulfidic material at four sites (wetland (WE), swamp scrub (SS), woodland (WO) and coastal tussock saltmarsh (CTS)) on the estuarine floodplain of the Anglesea River in southern Australia. Shell material and seawater buffered acidity generated and provided acid-neutralising capacity (up to 10.65% CaCO3-equivalent) at the sites located on the lower estuarine floodplain (WO and CTS). The SS site, located on the upper estuarine floodplain, can potentially acidify soil and water due to high positive net acidity (>200molH+t–1) and a limited acid-neutralising capacity. High titratable actual acidity in the SS and WO profiles (>270molH+t–1) were the result of high organic matter in peat-like layers that can potentially contribute organic acids in addition to acidity formed from oxidation of sulfidic sediments. The results of the present study suggest that the environments and chemistry of acid sulfate soils in southern Australia are distinct from those located in eastern Australia; this may be related to differences in estuarine processes that affect formation of acid sulfate soils, as well as the geomorphology and geology of the catchment.

PEUBAH KUALITAS AIR YANG MEMPENGARUHI PERTUMBUHAN RUMPUT LAUT (Gracilaria verrucosa) DI TAMBAK TANAH SULFAT MASAM KECAMATAN ANGKONA KABUPATEN LUWU TIMUR PROVINSI SULAWESI SELATAN

2009 ◽  
Vol 4 (1) ◽  
pp. 125
Author(s):  
Akhmad Mustafa ◽  
Rachmansyah Rachmansyah ◽  
Dody Dharmawan Trijuno ◽  
Ruslaini Ruslaini
Keyword(s):  
Water Quality ◽  
Growth Rate ◽  
Ammonium Phosphate ◽  
Gracilaria Verrucosa ◽  
Acid Sulfate Soils ◽  
Acid Sulfate Soil ◽  
Acid Sulfate ◽  
Independent Variables ◽  
Water Quality Variables ◽  
Sulfate Soils

Rumput laut (Gracilaria verrucosa) telah dibudidayakan di tambak tanah sulfat masam dengan kualitas dan kuantitas produksi yang relatif tinggi. Oleh karena itu, dilakukan penelitian yang bertujuan untuk mengetahui peubah kualitas air yang mempengaruhi laju pertumbuhan rumput laut di tambak tanah sulfat masam Kecamatan Angkona Kabupaten Luwu Timur Provinsi Sulawesi Selatan. Pemeliharaan rumput laut dilakukan di 30 petak tambak  terpilih selama 6 minggu. Bibit rumput laut dengan bobot 100 g basah ditebar dalam hapa berukuran 1,0 m x 1,0 m x 1,2 m. Peubah tidak bebas yang diamati adalah laju pertumbuhan relatif, sedangkan peubah bebas adalah peubah kualitas air yang meliputi: intensitas cahaya, salinitas, suhu, pH, karbondioksida, nitrat, amonium, fosfat, dan besi. Analisis regresi berganda digunakan untuk menentukan peubah bebas yang dapat digunakan untuk memprediksi peubah tidak bebas. Hasil penelitian menunjukkan bahwa laju pertumbuhan relatif rumput laut di tambak tanah sulfat masam berkisar antara 1,52% dan 3,63%/hari dengan rata-rata 2,88% ± 0,56%/hari. Di antara 9 peubah kualitas air yang diamati ternyata hanya 5 peubah kualitas air yaitu: nitrat, salinitas, amonium, besi, dan fosfat yang mempengaruhi pertumbuhan rumput laut secara nyata. Untuk meningkatkan pertumbuhan rumput laut di tambak tanah sulfat masam Kecamatan Angkona Kabupaten Luwu Timur dapat dilakukan dengan pemberian pupuk yang mengandung nitrogen untuk meningkatkan kandungan amonium dan nitrat serta pemberian pupuk yang mengandung fosfor untuk meningkatkan kandungan fosfat sampai pada nilai tertentu, melakukan remediasi untuk menurunkan kandungan besi serta memelihara rumput laut pada salinitas air yang lebih tinggi, tetapi tidak melebihi 30 ppt.Seaweed (Gracilaria verrucosa) has been cultivated in acid sulfate soil-affected ponds with relatively high quality and quantity of seaweed production. A research has been conducted to study water quality variables that influence the growth of seaweed in acid sulfate soil-affected ponds of Angkona Sub-district East Luwu Regency South Sulawesi Province. Cultivation of seaweed was done for six weeks in 30 selected brackishwater ponds. Seeds of seaweed with weight of 100 g were stocked in hapa sized 1.0 m x 1.0 m x 1.2 m. Dependent variable that was observed was specific growth rate, whereas independent variables were water quality variables including light intensity, salinity, temperature, pH, carbondioxide, nitrate, ammonium, phosphate, and iron. Analyses of multiple regressions were used to determine the independent variables which could be used to predict the dependent variable. Research result indicated that relative growth rate of seaweed in acid sulfate soils-affected brackishwater ponds ranged from 1.52% to 3.63%/day with 2.88% ± 0.56%/day in average. Among nine observed water quality variables, only five variables namely: nitrate, salinity, ammonium, phosphate and iron influence significantly on the growth of seaweed in acid sulfate soils-affected brackishwater ponds. The growth of seaweed in acid sulfate soils-affected brackishwater ponds of Angkona District East Luwu Regency, can be improved by using nitrogen-based fertilizers to increase ammonium and nitrate contents and also fertilizers which contain phosphorus to improve phosphate content to a certain level. Pond remediation to decrease iron content and also rearing seaweed at higher salinity (but less than 30 ppt) can also be alternatives to increase the growth of seaweed.

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