Recent changes to upland tarns in the English Lake District

Sediment cores were collected from three lakes in west Cumbria, UK, and the diatom assemblages were analyzed for temporal changes. All lakes revealed a similar pattern of change over the past 1000 yr. On the basis of the increase in acidophilous taxa, the pH has declined in the three lakes since about 1850, probably because of atmospheric deposition. The catchments are susceptible to acidification because of the low buffering capacity of their soils. The area has been an important industrial region for the past 200 yr, which has contributed to the general atmospheric pollution borne on prevailing winds.