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dc.contributor.author Ramjukadh, Carla-Louise
dc.contributor.author Silberbauer, M
dc.contributor.author Taljaard, Susan
dc.date.accessioned 2019-01-16T11:13:29Z
dc.date.available 2019-01-16T11:13:29Z
dc.date.issued 2018-10
dc.identifier.citation Ramjukadh, C-L., Silberbauer, M. and Taljaard, S. 2018. An anomaly in pH data in South Africa’s national water quality monitoring database – implications for future use. Water SA, vol. 44(4): 760-763 en_US
dc.identifier.issn 0378-4738
dc.identifier.issn 1816-7950
dc.identifier.uri https://journals.co.za/content/journal/10520/EJC-11e4a4b129
dc.identifier.uri http://hdl.handle.net/10204/10601
dc.description Article published in Water SA, vol. 44(4): 760-763 en_US
dc.description.abstract The South African national water quality database (Water Management System) houses data records from several environmental monitoring programmes, including the National Chemical Monitoring Programme (NCMP). The NCMP comprises an extensive surface water quality monitoring programme, managed by the Department of Water and Sanitation (DWS). The purpose of this technical note is to alert users to a systematic anomaly recently observed in the pH dataset of the NCMP, reflected in an abrupt increase between pre- and post-1990 data records. Although the cause of the anomaly in pH could not be confirmed with high confidence, an inappropriate acid rinse procedure in pre-1990 analytical methods was identified as the most likely cause, based on available evidence. This was supported by the variation in relative sensitivity when comparing the effect on waters with different buffering capacities, i.e., water with low buffering capacity (represented by total alkalinity < 10 mg/L, as CaCO(sub3) showing the largest anomaly, compared with waters of higher buffering capacity (represented by total alkalinity > 30 mg/L, as CaCO(sub3) showing the smallest anomaly. Historical pH data records in the NCMP (i.e. pre- 1990), therefore should be used with caution, especially in more weakly buffered systems. The possibility of reconstructing data using a correction factor derived from detailed statistical analyses of the post-1990 pH characteristics at selected sites is a possible solution that could be investigated in future. A key lesson learnt is the need to be diligent in capturing detailed meta-data on sampling procedures and analytical methods in datasets spanning several generations. Availability of such information is critical in order to provide users with a means of evaluating the suitability and comparability of data records in long-term datasets. The DWS includes such meta-data in the current version of the database, dating from about 1995 onwards. en_US
dc.language.iso en en_US
dc.publisher Water Research Commission en_US
dc.relation.ispartofseries Worklist;21849
dc.subject South African national water quality database en_US
dc.subject National chemical monitoring programme en_US
dc.title An anomaly in pH data in South Africa’s national water quality monitoring database – implications for future use en_US
dc.type Article en_US


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