Acidification and other chemical changes Halifax County lakes after 21 years

Sixteen of 23 lakes sampled in 1955 show no sign of significant physical alterations within their drainage basins over a 21‐year interval, so that chemical changes in these lakes can be assumed to reflect changes in atmospheric inputs. In all 16, the pH levels have declined, with greater declines in the higher pH (near neutrality) lakes. After correction for sea‐salt input, concentrations of sodium, magnesium, calcium, potassium, and sulfate show no significant change. Sulfate and hydrogen ions are significantly correlated and both show significant regressions on distance from the major sulfur‐emitting industrial sources in the Halifax area. Although the area as a whole may be subject to an influx of acid pollutants via long distance atmospheric transport, for lakes near Halifax the high acid levels are largely due to local pollution.