Modern catchment soil–lake sediment linkages: Proxy distribution patterns in a small lake in coastal Karnataka, southern India

This study presents a comprehensive assessment of the spatial variability of geochemical, biological, and physical proxies in catchment soils, surface sediments, and suspended particulate matter from Lake Ramasamudra (RSL), along with the factors governing these patterns. Using a multiproxy approach, it further examines the imprints of modern vegetation and chemical weathering on the catchment and lake sediments. The results show that magnetic minerals in the lake are largely lithogenic, with ferrimagnetic minerals dominating the catchment with minor contribution from antiferromagnetic minerals. Magnetic data suggests that the catchment acts as a magnetically enriched source. Magnetic concentrations decrease from soils to sediments and suspended particulate matter (SPM), likely due to dilution by non-magnetic particles and possible post-depositional dissolution of magnetite. The distribution of organic matter is influenced by shoreline hydrodynamics and differential degradation processes. Palynological records indicate that soils predominantly preserve local vegetation signals, whereas lake sediments integrate both local and regional pollen inputs. Spatial variability in proxy responses across the RSL catchment reflects the influence of slope, vegetation cover, rainfall, lake-level fluctuations, and soil properties. The consistency between recent regional environmental conditions and the proxy records indicates that these proxies reliably capture decadal-scale environmental variability in the study area.