What are the effects on the vegetation?
One of the most serious impacts of acid precipitation is on forests and soils. Great damage is done when sulphuric acid falls onto the earth as rain. Nutrients present in the soils are washed away. Aluminium also present in the soil is freed and this toxic element can be absorbed by the roots of trees. Thus, the trees are starved to death as they are deprived of their vital nutrients such as calcium and magnesium. Not all of the sulphur dioxide is converted to sulphuric acid. In fact, a substantial amount can float into the atmosphere, move over to another area and return to the soils unconverted. As this gas returns back to earth, it clogs up the stomata in the leaves, thus hindering photosynthesis. Research has been made where red spruce seedlings were sprayed with different combinations of sulphuric and nitric acid of pH ranging from 2.5 to 4.5. The needles of these seedlings were observed to develop brown lesions. Eventually, the needles fall off. It was also found that new needles
