The analysis of trace metals in surface waters from Scotland and Wales

188 water samples taken from Scottish and Welsh lakes in 1995/6 have been analysed for a range of trace metals, Hg, As, Se, Be, V, Cr, Co, Ni, Cu, Zn, Mo, Ag, Cd, Sb, Ba, Tl, Pb, & Bi. At all sites Hg, As, Se, Be, Bi, Pb and Ag were below limits of detection by the ICP-MS. The other elements showed various geographical distributions. In Wales, the south-central region and Anglesey appeared consistently higher and it is suggested that these are due to former mining and contemporary smelting activities respectively. In Scotland, distributions were move diverse although southern and south-west Scotland often appeared to show elevated levels as did sites on Orkney and Shetland. In general, lake sites in the north-west and Hebrides showed lower concentrations. Pnncipal Components Analysis (PCA) was used to try and determine any patterns in the data, but the results were inconclusive. The PC axes explained little of the variability within the data and clusters of sites on the bi-plots show little in common. However, only geographical location was available to be used m the PCA interpretation and it may be that other factors (lake and catchment characteristics, other water chemistry) would help explain the data more fully. The data included in this report are from smgle water samples taken over a short period of time. Therefore, althougl1 the data may show a useful 'snap-shot' of the situation, more information would be available from analyses of the sediment record (to put the data into temporal context) and other substrates where metal accumulation takes place. This would have the advantage of producing a time averaged metal value, but more importantly would mean more values above analytical detection and hence a better idea of metal distribution

The distribution of nitrate in UK surface waters and its implication for calculating critical loads: a preliminary assessment

Although increased nitrogen deposition is likely to have most serious consequences for soils and vegetation in the United Kingdom, surface waters are also affected, especially in areas of very high N deposition and where uptake by vegetation is reduced. In these areas high nitrate levels contribute significantly to lake acidity and may independently cause changes to the structure of aquatic communities