Influence of geochemical properties on natural radionuclides in the sediment of Asia's largest brackish water lagoon, Chilika-East Coast of India: evaluation through geo-statistical applications

The study signifies the first work on natural radioactivity and to identify the associations as well as influence of geochemical properties on it. The determination of the natural radioactivity such as: Ra-226, Th-232, and K-40 were carried out by gamma spectrometer and the median activities were found to be 26.27, 81.61, and 620.09 Bq kg(-1), respectively. The geochemical parameters are pH, sand, silt, clay, organic carbon (OC), calcium carbonate (CaCO3), magnesium (Mg), potassium (K), calcium (Ca), sodium (Na), iron (Fe), phosphorus (P) and nitrogen (N) has been determined. The lagoon was mostly dominated by muddy -type sediment which is nearly 60% of the total sample and the high pH noticed in the NS (7.58) of Chilika, which is due to the presence of grass and weeds, by their photosynthesis process, which may cause the lake slighter alkaline. The high Fe concentration (2.53%) in the NS may be due to rapid relies of iron, whereas the enrichment of Ca in CS (1.02%) in the sediment may be from land runoff. The influence and relations between geochemical and natural radionuclides of the sediment were evaluated through geo-statistics, such as correlation matrices, factor analysis, and cluster analysis.