RESULTS

Acid Waters Monitoring Network, UK

Long term response of surface water ANC from 1850 to 2150. Forecast scenarios from 1991 to 2150 represent four alternative acid deposition scenarios.

Scenario 1: Second S Protocol (red)

Scenario 2: Second S Protocol, remove all N deposition (green)

Scenario 3: All non-marine S removed from present deposition, N held constant at current level (light blue)

Scenario 4: all non-marine S and N removed from present deposition (purple)

Loch Chon

Trossachs region of central Scotland

Old Lodge

South-east England

Under Scenario 1 the long-term recovery in stream water ANC does not approach simulated background levels despite reductions in non-marine S deposition of the order of c.50-60% at all sites. Predicted responses fall into two categories:

• sites that demonstrate a sustained long term recovery in ANC including Loch Chon and sites 1,2,3,5,6,7,8,11,16,17,18,19,22
• sites that show short term recovery followed by continued acidification as a consequence of continued soil acidification such as Old Lodge and sites 4,9,10,13,14,15,20,21.

Sites showing long term deterioration under Scenario 1 and currently leaking N are predicted to recover under Scenario 2. Forecasts under Scenario 3 suggest that recovery is more pronounced , in terms of achieving background ANC, if all non-marine S is removed from deposition. Under Scenario 4, all sites recover towards background ANC but the return to background conditions is predicted to take several hundreds of years.

• References
• Contact point e-mail: Rachel Helliwell
• Acid Water Monitoring Network

Project Site Descriptions

• ABER, Wales,UK
• Speuld
• Kangasvaara
• Risdalsheia
• Awmn