Field measurements of major ions, phosphorus, nitrogen fractions, alkalinity and pH (2010-2015) [Wensum DTC]

Where/When

Study area

Temporal extent

2011-03-01    to    2015-03-31

Provenance & quality

The Wensum DTC has a monitoring network installed to measure meteorological, hydrological and hydrochemical parameters in target sub-catchments. This statement aims to describe the in-situ monitoring equipment, methods and protocols performed on our data before it is published on the archive. Quality assurance and quality control procedures Quality assurance (QA) procedures are followed during data collection, detailed with our monitoring equipment. Regular maintenance activities are carried out at a weekly frequency and involve cleaning of flow-through cells, clearing of in-channel vegetation and debris where stage is monitored and cleaning of rain gauges. All field work and maintenance activities are entered into maintenance logs for each site, which are used during data quality control (QC) procedures. QC procedures include the validation of high-frequency nutrient data using point samples in the Blackwater sub catchment. These samples are analysed in laboratories following standard methods. Inter-laboratory comparisons are used to check consistency in analytical procedures between sub-catchments. QC procedures also include the identification of errors in all data sets. Errors flagged as critical include: periods of maintenance when data may be unrepresentative; equipment of power failures; or data below limits of detection. On-site visits by field staff are recorded in a maintenance log which is checked against the data during the quality control (QC) post-processing. Any data likely to be disturbed by the routine field work are removed, along with any known periods of downtime, hence some of the data is not included and there may be time breaks in the files accessible on the archive. The Wensum DTC’s sampling kiosks monitor many hydrochemical parameters at a 30 minute resolution. Samples are also analysed less frequently at the University of East Anglia’s laboratory, all using standard laboratory methods. The monitoring equipment used is detailed below: Pressure transducer – Measures stage height. Sontek Argonaut – Doppler meter which measures stage height and infers flow from velocity and pre-programmed stream cross section. Sontek IQ – Doppler meter which measures stage height and infers flow from velocity and pre-programmed stream cross section. YSI 6600 series multi-parameter sonde - Measures water temperature, electrical conductivity, dissolved oxygen, pH, ammonium, turbidity and chlorophyll-a. Hach Lange Nitratax SC optical probe which measures N concentration. The Nitratax sensors are calibrated every 3 months using a standard solution. Hach Lange Sigmatax and Phosphax Sigma analyser (kiosk E and F only) - Measures total phosphorus and total reactive phosphorus colorimetrically using homogenised sample from Sigmatax. The Phosphax Sigma is automatically cleaned and calibrated daily using reagents that are replaced every 3 months. Routine laboratory water sample data Water samples are collected at the monitoring kiosk’s intake pipes and are analysed at the University of East Anglia’s laboratory using standard laboratory practices. ISCO water sample data Automatic ISCO samplers are installed at monitoring kiosks to measure hydrochemical properties of storm derived water. These are analysed at the University of East Anglia.

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