Vyrnwy research catchment hydrochemistry

Originally designed to improve understanding of water use by coniferous forests, monitoring within the Plynlimon/Vyrnwy research catchments has subsequently developed into a multi-disciplinary project underpinning a wealth of hydrological research. The stream hydrochemistry dataset is a combination of chemical determinands and in-situ physical properties. Samples are taken on an approximately weekly basis and analysed in laboratories for approximately 50 chemical determinands. The laboratory analysis has been undertaken at different locations using different equipment during the years of monitoring represented within the dataset. Details of the analytical methods used for each determinand are included within the dataset. The information provided is presented as raw data which have not been modified to include "less than" values when the numbers are less than the lowest quotable value. This is done so as to allow the data to be used for research purposes including detailed statistical analysis where inclusion of less than values would be problematic. The data are thus "uncensored" for research purposes and include in places values that are negative due to analytical uncertainties and the extremely low concentrations of some of the determinands. The data are provided in good faith with the expectation that they will be used in a positive and constructive manner. It is up to the user to resolve which way to use and interpret the data and information on full methodologies and less than values is provided within the metadata files. We whole heartedly encourage the use of these data for research and educational purposes bearing in mind that it is uncensored data and that over the years research directions have evolved to reflect changing project and funding priorities while analytical methodologies have changed. The data provide a legacy from many years' research involving scientists, analysts and field workers who in many cases have now retired. While we have done our best to provide all the information possible, in many cases it will be not be possible to respond to detailed enquiries about the earlier parts of the record.