Dissolved organic carbon (DOC) and labile organic compounds’ spatial and temporal variations in coastal Indian groundwater: their bioavailability and transfer to neighboring coastal waters of India

• Published in: Environmental science and pollution research international Vol. 31; no. 38; pp. 50820 - 50838
• Main Authors: Kumar, B. S. K., Sarma, V. V. S. S.
• Format: Journal Article
• Language: English
• Published: Berlin/Heidelberg Springer Berlin Heidelberg 01.08.2024; Springer Nature B.V
• Subjects: Amino acid composition; Amino acids; Anthropogenic factors; Aquatic Pollution; Aromatic compounds; Atmospheric Protection/Air Quality Control/Air Pollution; Bioavailability; Biogeochemical cycles; Carbohydrates; Carbon; Carbon - analysis; Carbon cycle; Chemical composition; Coastal waters; Dissolved organic carbon; Dry season; Earth and Environmental Science; Ecotoxicology; Environment; Environmental Chemistry; Environmental Health; Environmental Monitoring; Fluctuations; Food chains; Food webs; Groundwater; Groundwater - chemistry; Human influences; India; Land use; Leaching; Organic Chemicals - analysis; Organic compounds; Organic soils; Plankton; Population density; Research Article; Seasons; Sewage; Temporal variations; Waste Water Technology; Water analysis; Water Management; Water Pollutants, Chemical - analysis; Water Pollution Control; Water sampling; Woodlands; India; SGD; Carbohydrates; DOC; Labile organic compounds; Groundwater
• ISSN: 1614-7499; 0944-1344; 1614-7499
• DOI: 10.1007/s11356-024-34509-x

Submarine groundwater drainage (SGD) changes the elemental composition of the neighboring coastal ocean and impacts the biogeochemical cycles. To examine the seasonal and spatial variability in dissolved organic carbon (DOC) and labile organic compound biochemical compounds like dissolved carbohydrates (TDCHO), dissolved proteins (TDPRO), and dissolved free amino acid (TDFAA) concentrations during the dry and wet periods, groundwater samples were taken at 90 locations (180 samples) along the Indian coast. The mean DOC contents in Indian coastal groundwaters were more significant than the global mean values. DOC, TDCHO, TDPRO, and TDFAA concentrations are higher during wet than dry periods. The DOC and labile organic compound showed a substantial positive association with soil organic carbon, and respective labile compounds in soil, population, and land usage and poor relation with woodland territories, implying that soil organic compounds leaching is a source of DOC and other labile organic compounds into the groundwater. DOC and other labile compounds concentrations were linearly associated with population density, land usage, and sewage production, demonstrating that anthropogenic activities tightly regulate the formation of DOC in groundwater. During the wet and dry periods, total labile organic compounds (TDCHO, TDFAA, and TDPRO) constituted 21% and 10.5% of DOC, respectively. Compared to the wet time, more aromatic compounds accumulated during the dry season but were less bioavailable. SGD DOC flux contributed 2–7% of riverine DOC flux to the coastal ocean. The SGD flux from the Indian subcontinent to the nearby northern Indian Ocean accounts for approximately 2% of the worldwide SGD flux. The effect of DOC flux via SGD on coastal bacterial activity, the plankton food web, and the oxygen minimum zone must be studied.