The insitu source, primarily phytoplankton and aquatic vegetation along with C3 plants, are the dominant contributors to organic matter in the sediments. These findings have direct implications for integrated lake and watershed management, providing a scientific basis for targeted nutrient control, sustainable land-use planning, and ecosystem-based water governance. These findings were presented by Dr. Rajesh Kumar Ranjan, Associate Professor, Department of Environmental Science of Central University of South Bihar (CUSB) as an invited speaker at the 5th International Forum on Asian Water Environment Technology (IFAWET-5) organized at Dehradun August 06-08, 2025. Public Relation Officer (PRO) Mohammad Mudassir Alam said that at IFAWET-5, Dr. Ranjan presented the findings of his Science and Engineering Research Board (SERB)-funded project on Ghora Katora Lake in Rajgir, Bihar—an ecologically sensitive freshwater body of cultural and ecological significance. The study investigated nutrient source apportionment in lake sediments through an integrated approach, using bulk geochemical proxies such as Total Organic Carbon (TOC), Total Nitrogen (TN), and TOC/TN ratios, alongwith stable isotope analysis (δ¹³C, δ¹⁵N). Advanced modeling through the MixSIAR mixing model was employed to determine the contribution of various organic matter sources across pre-monsoon, monsoon, and post-monsoon seasons. Dr. Ranjan’s presentation highlighted how geochemical and isotopic tools can generate actionable knowledge for protecting freshwater ecosystems in tropical regions, aligning research with policy and community-level conservation efforts. With a Ph.D. in Environmental Sciences from Jawaharlal Nehru University and exchanged doctoral scholar at Stockholm University Sweden, Dr. Ranjan has over a decade of expertise in Environmental Chemistry, Biogeochemistry, and Aquatic Geochemistry. His research bridges advanced scientific methods with practical solutions for sustainable water resource management.