Spatio Seasonal Discrepancies in the Physico-chemical Parameters along the Surface Water of Gahirmatha Estuary, East Coast of India in the Bay of Bengal

Abstract

Water is a key factor in our lives, yet this valuable asset is progressively under threat. From the total share of the Earth's water, only 2% is fresh water, which is available for various life forms, including humans. Monitoring the quality of water is very important to check the physical, chemical, and biological characteristics, and the subsequent control of its wholesomeness. Particularly, the estuarine water bodies that are rich in diversity confront more threats for contamination in the entire riverine framework. This study was carried out to evaluate the current status of various physico-chemical properties of four different estuarine locations of the Gahirmatha coast, in the Indian state of Odisha in the eastern part of the Bay of Bengal: water temperature, pH, conductivity, TDS, TSS, turbidity, salinity, DO, BOD, total alkalinity, fluoride, Nitrite-N, Ammonia-N, Nitrate-N, phosphate, silicate, total chlorophyll. The study was carried out during the pre-monsoon (March to April) and post-monsoon (November to December) seasons in 2019. The surface water samples were collected from designated stations both during low tide and high tide to observe tidal influence. The data were subjected to statistical analysis regarding correlation coefficient, principal component analysis (PCA), and cluster analysis (CA) for interpretation. The Pearson correlation showed that the results were significantly correlated both at the 0.05 and 0.01 level of significance. When PCA was interpolated for the pre-monsoon and post-monsoon data, three broad groups were categorized. The highest eigen value was about 10.87 during the pre-monsoon and 9.07 during the post-monsoon season, and the cluster analysis showed there were two major groups of parameters with respect to the Euclidean distance. The observed variations in the concentration of these physico-chemical parameters in the estuarine waters of the Gahirmatha may be attributed to the riverine inputs from the catchment of rivers like the Brahmani, Baitarani, and Dhamra, which are associated with anthropogenic local activities.