The sulphur forms an integral part of the amino acids and proteins. It is also present in the enzymes and vitamins. It occurs in the element form as sulphides and sulphates. The gaseous form is almost nonexistent. The lakes, marshes and the water rich soils release a hydrogen bi sulphide which is changed into the sulphur dioxide. The fossil fuels also release a sulphur dioxide. It comes back to soil when it is dissolved in the rain water. The plants take sulphur in the form of sulphate which is changed into the organic compound. They enter the food chain from the plants and enter the soil through the dead bodies and excretions. The decomposers release hydrogen bi sulphide in the anaerobic respiration. It forms sulphates under the aerobic conditions. They also occur as sulphur. There are some bacteria and fungi which can change the hydrogen bi sulphide to sulphate and vice a versa. The sulphur can be transferred from the circulating pool to reservoir pool by the process of leaching and precipitation.
There are other minerals which are also very important. These are calcium, magnesium, zinc etc. They are an important segment of lithosphere and they are released when the rocks are exposed to the weather conditions. They are also found in the mining. They do occur as in the form of air or dust. They settle down to the soil or may enter into the water. They go into the plants and also involve the other organisms. The decomposers play a crucial role in the recycling. They break the organic matter and release energy in the form of minerals in the soil. They can be used by the organisms. There is a nonstop exchange of the materials between the surroundings and the organisms. The removals of nutrients have an adverse impact on the mineral cycles. They are deposited in the shells of skeleton and in the bottom of sea. A good amount of calcium is seen in the shells of corals and mollusks. There are certain shells and skeletons which are present on the land which release calcium. They degenerate at the lower rate. The organisms which are present at the bottom of sea return to the cycling pool after a large number of years. They become rock due to the disturbances in the earth.
