Please use this identifier to cite or link to this item:
|Scopus||Web of Science®||Altmetric|
|Title:||The application of a spectrophotometric method to determine pH in acidic (pH < 5) soils|
|Citation:||Talanta, 2018; 186:421-426|
|Sima Bargrizan, Ronald J. Smernik, Rob W. Fitzpatrick, Luke M. Mosley|
|Abstract:||pH is a "master variable" controlling many biogeochemical processes in soils. Acid sulfate soils undergo rapid and large pH changes from circumneutral pH under anaerobic soil conditions to sulfuric soils with ultra (pH < 3.5) and extremely (pH 3.5-4.4) acidic properties following oxidation. Measuring soil pH using a glass electrode has several potential drawbacks including liquid junction errors, drift, suspension effects and clogging. Spectrophotometric pH measurement, involving addition of an indicator dye to the sample, is widely used in seawater and has recently been developed for soil extracts at circumneutral pH ranges. The aim of this study was to extend the spectrophotometric method for application in ultra and extremely acidic soils. The acid dissociation constant (pKa = 5.02) and molar absorptivities of the indicator dye bromocresol green were determined and shown to enable spectrophotometric pH measurement between pH 3 - 5.3. To demonstrate the performance and application of the method, pH and metal availability (Fe, Al, Zn) were measured during the incubation of two acid sulfate soils, which both classified as hypersulfidic soils (pH > 4) and transformed to sulfuric soils (pH < 4) after incubation for 12 weeks. The method compared well (r2 > 0.99) to glass electrode measurements under acidic conditions with high metal availability. The method has potential to improve understanding of biogeochemical processes in ultra and extremely acidic soils.|
|Keywords:||Soil pH; Acid sulfate soils; Indicator dye; Bromocresol green|
|Description:||Available online 24 April 2018|
|Rights:||© 2018 Elsevier B.V. All rights reserved.|
|Appears in Collections:||Agriculture, Food and Wine publications|
Files in This Item:
There are no files associated with this item.
Items in DSpace are protected by copyright, with all rights reserved, unless otherwise indicated.