SCPs in the Upland Waters Monitoring Network
The Upland Waters Monitoring Network (UWMN; formerly the Acid Waters Monitoring Network) was established in 1988 to monitor the chemical and biological impacts and recovery of UK lakes and streams from acid deposition. As unambiguous indicators of industrial coal and oil combustion, and hence a direct link to one of the main sources of acid deposition, SCPs have been monitored in the lake sites of the UWMN since its inception using annual sediment traps.
Sediment traps collect the material settling to the bottom of a lake which eventually form the sediment record. SCPs are analysed from the material collected from these traps which are emptied each summer. As the date of sediment trap deployment and emptying are precisely known the rate of SCP input can be calculated at high resolution to determine inter-annual variation. Through comparison with lower resolution data obtained via lake sediment cores from the same UWMN lakes, comparison of the contemporary status of SCP input can also be placed in its historical context back to the mid-19th century.
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(Photo: Ewan Shilland)
An example of the SCP flux data taken from the UWMN web site is shown. Here, data are shown in units of 'no. cm-2 yr-1'. (Note: '+' indicates where SCPs have been observed but where the flux is less than 50 cm-2 yr-1).
At all sites, SCP fluxes observed in most recent sediment trap samples are far lower than the peak values observed in sediment cores taken from these lakes in the late-1970s and are back to levels seen in the early decades of the 20th century. This reflects a decline in SCP emission and deposition and parallels observed improvements in lake water chemistry seen across the UWMN.
With a dataset now exceeding 35 years the UWMN is a monitoring programme of exceptional value. To my knowledge there are no other SCP lake monitoring programmes of this duration.
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More information and data plots can be obtained from the UWMN webpage: https://uwmn.uk/