Sulfur Cycle PDF

Sulphur/Sulfur (S) cycle  The importance of S A key component of many amino acids and proteins and plays a significant part in biological processes. Producing fossil fuels such as coal, petroleum and natural gas Contributing to a majority of metal deposits because of its ability to act a...

Sulphur/Sulfur (S) cycle  The importance of S A key component of many amino acids and proteins and plays a significant part in biological processes. Producing fossil fuels such as coal, petroleum and natural gas Contributing to a majority of metal deposits because of its ability to act as an oxidizing as well as reducing agent Serving as the source of energy to the sulfur-reducing bacteria present in the hydrothermal vents Reducing global warming caused by the greenhouse gases by absorbing the ultraviolet radiation of the sun Frequently employed in a wide range of industrial applications, including the manufacture of fertilizers, medicines, and rubber goods. S is necessary for the formation of chlorophyll  Forms of S: Sulfur: S Hydrogen sulphide: H2S Dimethyl sulphide: C2H6S Sulphur dioxide: SO2 Sulphur trioxide: SO3 Sulphuric acid: H2SO4 Sulphate: SO4 Ammonium sulphate: (NH4)2SO4 In its most common organic form, it is not assimilated by plants. In order to be absorbed, organic sulfur must be oxidized by soil microorganisms (oxidative sulfur bacteria such as thiobacilli (Thiobacillus), which then transform it into sulfate SO42-, its ionic form, which can be assimilated by plants.  Steps of Sulfur cycle 1) Formation of inorganic sulfur (e.g. hydrogen sulfide) 2) Oxidation of inorganic sulfur to sulfate (SO42−) It occurs through two different processes: It involves two steps – i. Hydrogen sulfide is oxidized to produce elemental i. Biological – By decomposers present in the soil sulfur by certain photosynthetic bacteria such ii. Geological – Through weathering of rocks formed from as Chlorobiaceae and Chromatiaceae species geological uplift ii. Elemental sulfur is then converted to sulfate by chemolithotrophic bacteria 3) Assimilative reduction of sulfate to sulfide (S2−) 4) Incorporation of sulfide into organic compounds Also known as sulfur reduction, it is performed by plants, The sulfide assimilated is converted into an organic fungi and various microorganisms such form which the animals consume and fix through the as Desulfovibrio and Desulfobulbus species in two steps: foods they eat. i. Sulfates are converted to sulfites Once these plants and animals die, decomposers ii. Reduction of sulfites to hydrogen sulfides release the fixed organic sulfur back into its free form as elemental sulfur. Importance of sulfur cycle 1. Sulfur is an essential nutrient for living organisms, as it is required for the formation of amino acids and proteins. The sulfur cycle assures that sulfur is accessible for usage in plant and animal development and metabolism. 2. Acid rain: The sulfur cycle has been implicated in acid rain formation. Understanding the sulfur cycle is critical for regulating the effects of acid rain and mitigating its detrimental consequences. 3. Geological processes: Sulfur is involved in geological events such as rock weathering and mineral formation. The cycling of sulfur aids in the regulation of these activities and in the preservation of a stable sulfur equilibrium in the environment. 4. Carbon cycling: The sulfur cycle is inseparably connected to the carbon cycle, as sulfur compounds in the atmosphere may influence cloud formation and sunlight reflection, hence influencing world temperatures and climate patterns. 5. Human activities: Human activities such as the combustion of fossil fuels and industrial operations. It can emit sulfur dioxide and other sulfur compounds into the atmosphere, which can harm the quality of water and air. Studying the cycle is critical for mitigating the effects of these activities and supporting environmentally friendly behaviors. Human impact on sulfur cycle 1. Fossil fuel combustion: The burning of fossil fuels emits huge volumes of sulfur dioxide into the atmosphere - generation of acid rain. 2. Industrial operations: Sulfur dioxide and other sulfur compounds are released into the atmosphere by many industrial activities, including metal smelting and paper manufacture. This can contribute to acid rain and other harmful environmental impacts. 3. Agriculture: The use of sulfur-containing fertilizers can raise sulfur levels in the soil and groundwater. This has the potential to harm aquatic ecosystems and water quality. 4. Mining: Mining activities can cause sulfur-containing minerals to be released into the environment, contributing to acid mine drainage and other detrimental effects on water quality. 5. Garbage disposal: Improper disposal of sulfur-containing garbage, such as batteries and electronic equipment, can result in sulfur emission into the environment. Overall, human activities can disrupt the natural balance of the sulfur cycle, leading to negative impacts on the environment and human health.