Abstract

During the eighties of the previous century acid rain was regarded as an important environmental issue and received ample attention. Forests died and organisms disappeared from rivers and lakes. Air pollution was identified as the cause of acid rain. Atmospheric emissions from industry, traffic and agriculture contain nitrogen and sulphur. These substances are transported through the atmosphere and reach the ground elsewhere, causing acidification and eutrophication of soil and water. This process adversely affects the quality of soil, water and biodiversity. Measures taken at the international level to reduce the emission of nitrogen and sulphur appear to have yielded results. RIVM studies show that acidification is still ongoing at most monitoring locations in the Netherlands, but at a slower pace than before. Because of the reduced emissions, rainwater quality has improved between 1989 and 2010. Consequently, less nitrogen and sulphur now reaches the ground. This has a positive impact on shallow groundwater: the amount of nitrogen and sulphur has dropped by tens of per cents. The current study is the first extensive analysis of the data collected within the framework of the National Acidification Trend Monitoring Network. This network, established in 1989, focuses on forested natural areas with sandy soils. The network monitors the impact of atmospheric deposition of acidifying and eutrophying substances on the groundwater quality at 150 locations in the Netherlands. The literature shows that, despite the positive developments, ecosystems have not yet recovered from the acidifying and eutrophying impacts of air pollution. The eutrophication of nature areas in the Netherlands, induced by the atmospheric deposition of nitrogen, is still a major threat to plant species diversity. At two thirds of the locations investigated, deposition still exceeds the critical load. Acidification also poses a problem, but a less pressing one.