Geochemical and sedimentological properties of surface sediments from the Firth of Lorn and adjacent fjords

Data 1 This dataset comprises of 440 seabed sediment samples collected from Scottish coastal and fjordic environments, (55.5 to 56.7° N; −5.6 to −6.8° W). Sampling depths range from shallow coastal settings (~3 m) to outer shelf and fjord basins (>180 m), with distances to land spanning nearshore (0 km) to >170 km. Each row represents an individual sediment sample identified by a unique survey/sample ID and includes detailed spatial metadata (latitude, longitude, water depth, distance to land) and sampling information, including the sampling method (Day grab, Van Veen grab, gravity corer, Craib corer, Shipek) and site classification. The dataset contains comprehensive sediment biogeochemical measurements, with a focus on organic matter quantity, quality, and provenance. Variables include: Organic matter fractions (labile OM , recalcitrant + refractory OM), Total organic carbon (OC %) and total nitrogen (N %), Stable isotope ratios (δ¹³Corg, δ¹⁵N), Elemental ratios (C/N, N/C) Derived terrestrial organic carbon fraction with associated uncertainty) Sedimentological properties (mean grain size, median grain size, surface area, OC loading) Seabed hydrodynamics (Modelled bed shear strength) Data 2 This dataset comprises radiocarbon (14C) for a subset of samples (n = 37). Precise geographic coordinates (latitude, longitude) and water depths (m) are provided for each sample. Variables include: Fraction modern carbon (Fmodern) and associated uncertainty Percent modern carbon (%modern) and uncertainty Conventional 14C age (years BP) and uncertainty (where applicable) Δ¹⁴C (‰) and/or D¹⁴C (‰) with analytical uncertainty