S. Siji ^a,b, A. Krishnakumar^a*, K. Anoop Krishnan^a and Sumedh Humane^c

^aNational Centre for Earth Science Studies, Ministry of Earth Sciences, Govt. of India, Akkulam, Thiruvananthapuram-695011(KL), India

^bDepartment of Environmental Sciences, University of Kerala, Thiruvananthapuram-695034 (KL), India

^cDepartment of Geology, Rashtrasant Tukadoji Maharaj Nagpur University, Nagpur-440001(MS), India

(*Corresponding Author, E-mail: drakrishnakumar@gmail.com)

Abstract

River water quality is receiving increasing attention worldwide due to its vital role in supporting ecosystems, agriculture, and human livelihoods. To maintain the stability of the ecosystem, it is essential to assess the water quality and contamination status of surface water resources. To create baseline data on the water quality and pollution status, surface water samples were taken from 20 different locations of the Karuvannur River, originating from the Southern Western Ghats and traversing the Kole Wetlands in the Thrissur District of Kerala state, India. The samples were analysed for physico-chemical parameters such as pH, EC, TDS, Cl−, SO 2−, NO −, Ca2+, Mg2+, Alkalinity, Hardness, DO, and BOD. The concentration of the tested parameters was within the permissible limit for domestic and agricultural purposes recommended by the World Health Organization and the Bureau of Indian Standards. The Water Quality Index (WQI) was calculated, and according to the results, all the samples fall under the ‘good’ category, ranging from 26.42 to 46.84 with an average of 34.48, and are presently devoid of any potential contamination risks. The partial pressure of CO2 (pCO2) of the surface water of the Karuvannur River ranges from 1,076 to 13,908 μatm, which is comparatively higher than the typical atmospheric concentration of 380μatm. The oversaturation of pCO2 signifies that the river actively contributes to the global carbon budget by releasing CO2 into the atmosphere. By quantifying pCO2 and linking it with hydrochemical characteristics, this study provides critical insights into carbon flux dynamics in tropical river systems, improving understanding of their contribution to regional and global carbon budgets and informing strategies for sustainable watershed management.

Keywords: Karuvannur River Basin, Kole Wetlands, pCO2, Water Quality Index, Western Ghats