A FRAMEWORK FOR THE ANALYSIS OF HARMONISED MONITORING SCHEME DATA FOR ENGLAND AND WALES

摘要: The Harmonised Monitoring Scheme (HMS) records are the best long-term data sets for river water quality in Britain. A simple framework statistical analysis of these is developed which copes with many observations below limits detection laboratory analytical methods used to measure concentrations chemical determinands. Besides estimates annual mean concentrations, two products precision means and a test change concentration. methodology applied ammoniacal nitrogen, chloride, nitrite, nitrate, orthophosphate, copper zinc at HMS sites England Wales. These show clear net improvement when comparing late-1970s early-1990s. Conversely, between same periods, deterioration chloride orthophosphate small nitrate concentration sites. extended include seasonal component full likelihood change. This nitrogen 30 proportion showing little higher than that obtained framework, suggesting approach conservative detecting