Biogeochemical cycling of sulphur and iron in Ithikkara lake; Kollam district, Kerala, India: a probable mechanism

The Ithikkara lake in Kollam District of Kerala State, India has been studied over a decade (2005-2015) in the context of biogeochemical cycling of iron and sulphur. The study includes the analyses of water and mud samples from the lake on a monthly basis. The parameters measured include pH and electrical conductivity of water and physicochemical and mineralogical characteristics (by XRD and thermal methods) of the mud. Simultaneously both the mud and water samples were tested for the presence of microorganisms. The water remained more or less pH neutral throughout the period of study. The mud is found to be rich in kaolinitic clays with the presence of minor minerals like pyrite, sulphur particles and calcareous materials. Different types of sulphur and iron bacteriae were present in both mud and water. A probable mechanism for the biogeochemical cycling of iron and sulphur aided by all types of sulphur and iron bacteriae, benthic organisms, fungi and water plants is described in this paper.