Acid deposition at Rothamsted, Saxmundham and Woburn, 1969–83

Rainfall has become less acid at Rothamsted and Saxmundham over the period 1969–83. The pH of rain at these two sites has increased from 4.4–4.6 to about 4.8–4.9; at Woburn it has remained approximately constant at 4.4–4.6. Amounts of NH4‐N and NO3‐N deposited at present are 10–15 and 5–10 kg ha−1 a−1 respectively. They have been increasing at Rothamsted and Woburn. Some 50–60 kg ha−1 a−1 of Cl and 25–35 kg ha−1 a−1 of SO4‐S are presently deposited. Deposition of non‐sea Cl and SO4‐S has been increasing markedly at all three sites. Non‐sea salts comprise 35% of the total salt deposition near the coast at Saxmundham, 58% inland at Rothamsted and Woburn