Changes in rainfall chemistry and airborne particulates during a period of major local industrial change

Data from a site in central Scotland were used to quantify the changes in rainfall quality from 1989 to 1998. During this period there have been major changes in industrial activities in the area, particularly the decline in local steel-making and steel-processing activities. Many element concentrations in rainfall decreased over time in parallel with the phased reduction in the activity of local pollutant sources. Trend analyses of the rainfall data identified that the most significant responses have been the lower concentrations of Ca, SO4-S and Mn. There was also a dramatic decline in the capture of airborne particulates by the interception rainfall gauges. Particulates were found to contain mainly hematite, magnetite and quartz, that is similar to what would be expected to be derived from the neighbouring steel industries. The eventual disappearance of these particulates and the responses in rainfall quality match the timescale for the decline and closure of some of the potential sources of pollutants.