A biological diatom indices based preliminary assessment of water quality of Thamirabarani river, Southern India

Diatoms have long been used as bio-indicators for the assessment of surface water quality. This study investigates the biological diatom index (BDI) and water quality index (WQI) for evaluating the water quality impact in the Thamirabarani River, Southern India. Diatom and water samples were taken for the present investigation from ten different locations along the river. The samples were enumerated and the morphometrics valve was documented by light microscopy. In the study area, a total of 70 diatom taxa belonging to 28 genera were recorded. The diatom indices implemented in OMNIDIA software version 6.1 was used to infer the river water quality status. The results showed that based on the BDI and WQI analysis values varied from 6.7 to 17.4 and 48 to 71 were observed. According to the BDI and WQI analysis result during the study period in the river revealed the water quality varied between good (Oligo-mesotrophic) to bad (Eutrophic) ecological conditions. The biological diatom index and water quality index results indicate the respective locations (Site 2, Site 3, Site 7, Site 8, Site 9 and Site 10) represent bad water quality. The result indicated moderate water quality at Sites 4 and Site 6. The diatom indices and water quality index results show the locations Site 1, and Site 5 indicate good water quality. The biological diatom index results from diatom assemblages show more information about the water quality and environmental impact on the river. For the national assessment of water quality better to use diatoms along with physico-chemical parameters variables. Based on the analysis result reveal that the major component of water quality degradation was due to anthropogenic activities, domestic waste and industrial effluents in the study area.