Continuous pH, electrical conductivity and temperature measurement at Plynlimon: towards an integrated, reliable and low maintenance instrument system

Hodgson, P.; Evans, J.G. ORCID: https://orcid.org/0000-0003-4194-1416. 1997 Continuous pH, electrical conductivity and temperature measurement at Plynlimon: towards an integrated, reliable and low maintenance instrument system. Hydrology and Earth System Sciences, 1 (3). 653-660.

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Abstract/Summary

Water quality data for the Nant Tanilwyth stream, Plynlimon (an acidic upland stream, the waters of which are of such low ionic strength that measurement is difficult), has been recorded using a new integrated field instrument system. The negligible drift of the pH electrode allows the system to operate for extended periods (months) without re-calibration, whilst maintaining a standard deviation of 0.19 pH units between its readings and laboratory reference measurements. Conductivity measurements, although within the sensor manufacturer's specification, did not provide meaningful readings at conductivities below 50 μS cm-1. Using the pH data as a surrogate tracer, a high temporal resolution estimate of the stream dynamics, in terms of the contributions of groundwater and soil-water is presented; the dependence of these relative proportions on instantaneous flow and antecedent conditions is shown. It is concluded that, whilst improvements in instrumentation have been made, greater accuracy is still desirable for some scientific applications and ways forward are described.

Item Type:	Publication - Article
Programmes:	CEH Programmes pre-2009 publications > Other
UKCEH and CEH Sections/Science Areas:	_ Pre-2000 sections
ISSN:	1027-5606
Additional Keywords:	Instrumentation, Measurement
NORA Subject Terms:	Hydrology
Date made live:	02 Jun 2009 07:34 +0 (UTC)
URI:	https://nora.nerc.ac.uk/id/eprint/7338

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