DOI: 10.5285/00895096-e083-498f-9a52-b7f9e3291125
title: Continuous measurements of conductivity, dissolved oxygen, pH, temperature and water level in rivers (2002-2007) [LOCAR]

description: Continuous measurements of conductivity, dissolved oxygen, pH, temperature and water level from the Frome Piddle; Pang Lambourn and Tern catchments, recorded between 2002 and 2007. YSI sondes were installed at 16 sites in these catchments to record continuous measurements of conductivity, dissolved oxygen, pH and temperature. Druck pressure transducers were installed at the same sites to measure continuous water level values. The instruments were installed as part of the NERC funded Lowland Catchment Research (LOCAR) Programme to provide comparable baseline river water chemistry data across the LOCAR catchments. Data were collected continuously at 15-minutes intervals for periods of variable length, depending on site.
description: Temperature, pH, conductivity and dissolved oxygen data were collected using YSI 6-Series multi-parameter water quality sondes. Each sonde had multiple sensors that read water quality data. Water level data were collected using Druck Pressure Transducers. The transducers were fully submersible high performance sensors that produced reliable and accurate water level measurements. After two weeks of deployment in the river the sondes were taken back to the laboratory for calibration checks, cleaning, changing the membrane on the oxygen electrode and recalibration. During their transportation and storage they were kept moist at all times by adding a few drops of deionised water in the containing bottle. On return to the laboratory, the outside of the sonde body was wiped to remove silt, etc. The electrode guard was removed and the body of the electrode rinsed, avoiding cleaning the surface of the electrodes. The sonde was then connected to the battery pack and computer and the calibration software launched. Then, in the corresponding calibration software menus, the specific conductance, conductivity, dissolved oxygen charge were activated and their post calibration values recorded in the post calibration form. Before the sondes could be returned to the field they needed to be recalibrated. First, the glass surface of the pH electrode was gently wiped with a cotton bud wetted in alcohol. The inside of the conductivity electrode was scrubbed with a small bottle brush then the sonde was rinsed with distilled water. The 'O' ring was removed and the plastic membrane from the oxygen electrode was replaced by a new one. The 'O' ring was then replaced. The new membrane needed at least 12 hours to condition before calibration. The sonde was therefore left in the transportation pot (containing moist sponge) until the next day before being calibrated. To calibrate the sonde, it was connected to the battery pack and the computer. From the calibration routine, in the sonde software menu, the dissolved oxygen charge was activated. Then dissolved oxygen, conductivity and pH were consecutively selected for calibration. The Catchment Service Team in each catchment was responsible for installing, maintaining and downloading the loggers on the YSI sondes and Druck pressure transducers at each site on a regular basis. Data are raw and have not been quality controlled nor corrected for instrument failure or instrument drift. A zip file containing box-and-whisker plots for each determinand, showing the range of values (median, inter-quartile range, 1.5 * inter-quartile range, outliers) recorded at each site is available to enable prospective users of the data to understand data quality. (For further details see the supporting documentation for this dataset)