Evaluation of different approaches to quantify strong organic acidity and acid-base buffering of organic-rich surface waters in Sweden
2002 (English)In: Water Research, Volume, Vol. 36, no 18, 4487-96 p.Article in journal (Refereed) Published
The role of organic acids in buffering pH in surface waters has been studied using a small brownwater stream (26mgL-1 TOC) draining a forested catchment in Northern Sweden. Under the conditions of elevated pressure of CO2 stream field pH was changed between 3.5 and 6.1 during the acidification and alkalinization experiment. Acid-base characteristics of the natural organic matter were also determined using a high precision potentiometric method for a concentrated sample from the same stream. We compared the predictions from the Windermere Humic Aqueous Model (WHAM Model V), a model derived from the potentiometric titration (diprotic/monoprotic acid model) and a previously derived triprotic acid model which only uses alkalinity and TOC as input variables. The predicted buffering characteristics of all three models are very similar in the pH range 4.5-7 which suggests that during routine analysis alkalinity and TOC are sufficient to give a good estimate of organic acid anion charge contribution in a large range of surface waters. A slightly adjusted version of WHAM V successfully describes the organic charge contribution in a large number of sampled surface water lakes, which were previously used to calibrate the triprotic model.
Place, publisher, year, edition, pages
2002. Vol. 36, no 18, 4487-96 p.
Organic acidity, Air-equilibrated pH, Alkalinity, WHAM V, Surface waters
IdentifiersURN: urn:nbn:se:umu:diva-9060DOI: doi:10.1016/S0043-1354(02)00187-2OAI: oai:DiVA.org:umu-9060DiVA: diva2:148731