At all stream sites water samples for chemical analysis are collected monthly, whereas lake sites, because water chemistry fluctuates less, are sampled on a quarterly basis. All dip samples are collected in acid-rinsed bottles.
The chemical determinands recorded at each site are those recommended by the Acid Waters Review Group (Warren et al. 1986). Accuracy requirements were established in accordance with Water Research Centre (WRc) recommendations and UK water industry practice. The UK UWMN laboratories regularly participate in ICP Waters international water chemistry intercalibration exercises (eg. Hovind H., 2004; Hovind H., 2005; Hovind H., 2006; Hovind H., 2007; Hovind H., 2009; Dahl I. and Hagebo E., 2011; Dahl I., 2012; Escudero-Onate C., 2013; Escudero-Onate C., 2014; Escudero-Onate C., 2016).
A range of laboratories used to contribute chemical analyses. Today, most analysis is performed by the analytical chemistry facility at the UK Centre for Ecology & Hydrology, Lancaster. To maintain temporal consistency, determinands considered to require particularly prompt analysis (pH, Gran Alkalinity and electrical conductivity) in samples from sites in Wales are analysed at the UK Centre for Ecology & Hydrology, Bangor. The tables below summarise the methods utilised and detection limits for the analysis of each determinand. The freshwater laboratory at Marine Scotland, Pitlochry, used to provide analysis for a significant proportion of the network, and continues to provide analysis for the Baddoch Burn.
UK Centre for Ecology & Hydrology Lancaster methods and detection limits
| Determinand | Minimum Detection Limit (mg l -1) | Method |
|---|---|---|
| Alkalinity | Dual end-point Gran titration. Mettler-Toledo DL53 autotitrator | |
| Dissolved Organic Carbon | 0.5 | Shimadzu TOC-Vcph analyser |
| Ca | 0.0029 | Perkin Elmer DV 4300 ICP-OES |
| Mg | 0.0010 | Perkin Elmer DV 4300 ICP-OES |
| Na | 0.0025 | Perkin Elmer DV 4300 ICP-OES |
| K | 0.0094 | Perkin Elmer DV 4300 ICP-OES |
| Fe | 0.0003 | Perkin Elmer DV 4300 ICP-OES |
| Al | 0.0024 | Perkin Elmer DV 4300 ICP-OES |
| V | 0.00002 | Perkin Elmer DRCII ICP-MS |
| Cr | 0.00004 | Perkin Elmer DRCII ICP-MS |
| Mn | 0.000006 | Perkin Elmer DRCII ICP-MS |
| Fe | 0.0003 | Perkin Elmer DRCII ICP-MS |
| Co | 0.000006 | Perkin Elmer DRCII ICP-MS |
| Ni | 0.00001 | Perkin Elmer DRCII ICP-MS |
| Cu | 0.000002 | Perkin Elmer DRCII ICP-MS |
| Zn | 0.001 | Perkin Elmer DRCII ICP-MS |
| As | 0.000008 | Perkin Elmer DRCII ICP-MS |
| Se | 0.000043 | Perkin Elmer DRCII ICP-MS |
| Sb | 0.00013 | Perkin Elmer DRCII ICP-MS |
| Cd | 0.000012 | Perkin Elmer DRCII ICP-MS |
| Pb | 0.000059 | Perkin Elmer DRCII ICP-MS |
| Al | 0.00059 | Perkin Elmer DRCII ICP-MS |
UKCEH Lancaster accredited to ISO/IEC 17025:2005. Search for United Kingdom Accreditation Service (UKAS) laboratory details.
UK Centre for Ecology & Hydrology Bangor methods and detection limits
| Determinand | Minimum Detection Limit (mg l -1) | Method |
|---|---|---|
| pH | Metrohm Auto-titration | |
| Alkalinity | 0.001 | Metrohm Auto-titration |
| Conductivity | Jenway 4320 Conductivity Meter |
References
- Dahl I, Hagebo E. International Cooperative Programme on Assessment and Monitoring of Acidification of Rivers and Lakes. Intercomparison 1125:pH, Conductivity, Alkalinity, NO3-N, Cl, SO4, Ca, Mg, Na, K, TOC, Al, Fe, Mn, Cd, Pb, Cu, Ni and Zn. 1-77. (2011). Oslo, Norway, NIVA.
- Dahl I. International Cooperative Programme on Assessment and Monitoring of Acidification of Rivers and Lakes. Intercomparison 1226:pH, Conductivity, Alkalinity, NO3-N, Cl, SO4, Ca, Mg, Na, K, TOC, Al, Fe, Mn, Cd, Pb, Cu, Ni and Zn. 1-92. (2012). Oslo, Norway, NIVA.
- Escudero-Onate C. International Cooperative Programme on Assessment and Monitoring of Acidification of Rivers and Lakes. Intercomparison 1327:pH, Conductivity, Alkalinity, NO3-N, Cl, SO4, Ca, Mg, Na, K, TOC, Al, Fe, Mn, Cd, Pb, Cu, Ni and Zn. 1-93. (2013). Oslo, Norway, NIVA.
- Escudero-Onate C. International Cooperative Programme on Assessment and Monitoring of Acidification of Rivers and Lakes. Intercomparison 1428:pH, Conductivity, Alkalinity, NO3-N, Cl, SO4, Ca, Mg, Na, K, TOC, Al, Fe, Mn, Cd, Pb, Cu, Ni and Zn. 1-88. (2014). Oslo, Norway, NIVA.
- Escudero-Onate C. International Cooperative Programme on Assessment and Monitoring of Acidification of Rivers and Lakes. Intercomparison 1630:pH, Conductivity, Alkalinity, NO3-N, Cl, SO4, Ca, Mg, Na, K, TOC, Al, Fe, Mn, Cd, Pb, Cu, Ni and Zn. 1-71. (2016). Oslo, Norway, NIVA.
- Hovind H. International Cooperative Programme on Assessment and Monitoring of Acidification of Rivers and Lakes. Intercomparison 0418: pH,K25,HCO3, NO3+NO2, Cl, SO4, Ca, Mg, Na, K, Fe, Mn, Cd, Pb, Cu, Ni and Zn. 1-69. (2004). Oslo, Norway, NIVA.
- Hovind H. International Cooperative Programme on Assessment and Monitoring of Acidification of Rivers and Lakes. Intercomparison 0519: pH, Cond, HCO3, NO3+NO2, C1, SO4, Ca, Mg, Na, K, Fe, Mn, Cd, Pb, Cu, Ni, and Zn. 1-70. (2005). Oslo, Norway, NIVA.
- Hovind H. International Cooperative Programme on Assessment and Monitoring of Acidification of Rivers and Lakes. Intercomparison 0620: pH, Cond, HCO3, NO3+NO2, Cl, SO4, Ca, Mg, Na, K, Fe, Mn, Cd, Pb, Cu, Ni and Zn. 1-69. (2006). Oslo, Norway, NIVA.
- Hovind H. International Cooperative Programme on Assessment and Monitoring of Acidification of Rivers and Lakes. Intercomparison 0721: pH, Cond, HCO3, NO3-N, C1, SO4, Ca, Mg, Na, K, Fe, Mn, Cd, Pb, Cu, Ni, and Zn. 1-68. (2007). Oslo, Norway, NIVA.
- Hovind H. International Cooperative Programme on Assessment and Monitoring of Acidification of Rivers and Lakes. Intercomparison 0923: pH, Cond, HCO3, NO3-N, Cl, SO4, Ca, Mg, Na, K, TOC, Al, Fe, Mn, Cd, Pb, Cu, Ni, and Zn. 1-73. (2009). Oslo, Norway, NIVA.
- Hovind H. International Cooperative Programme on Assessment and Monitoring of Acidification of Rivers and Lakes. Intercomparison 1024: pH, Cond, HCO3, NO3-N, Cl, SO4, Ca, Mg, Na, K, TOC, Al, Fe, Mn, Cd, Pb, Cu, Ni, and Zn. 1-77. (2010). Oslo, Norway, NIVA.
- Warren, S. C., Bache, B. W., Edmunds, W. M., Egglishaw, H. J., Gee, A. S., Hornung, M., Howells, G. D., Jordan, C., Leeming, J. B., Maitland, P. S., Pugh, K. B., Sutcliffe, D. W., Wells, D. E., Cape, J. N., Ellis, J. C., Hunt, D. T. E., Wilson, R. B. & Watson, D. C. (1986) Acidity in United Kingdom fresh waters. United Kingdom Acid Waters Review Group interim report. Department of the Environment, London.