|MadSci Network: Botany|
Sulfur is an essential mineral element that is used in building amino acids such as cysteine and methionine to make up proteins.
Industrialization, namely the burning of fossil fuels, releases gaseous forms of sulfur such as sulfur dioxide (SO2), which makes its way into the soil by dissolving in rain. When dissoved in water, sulfur dioxide combines with water to become a strong acid, sulfuric acid (H2SO4). The sulfuric acid is a major source of the acid in acid rain.
Plants will take in and metabolize SO2 in gaseous form via their stomata - small pores found on leaves. If plants are exposed to high atmospheric concentrations of SO2 (considered > 8 hours, and over 0.3ppm or 'parts per million' of SO2 in the air), extensive tissue damage occurs in the plant due to the reaction of H2SO4 with the cells.
You might examine which form of sulfur dioxide uptake is worse for the plant- dissolved in water in the soil, or in its gaseous state in the atmosphere.
Reference: Plant Physiology by Taiz and Zeiger, 1991.
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