Accumulation of Organic Matter, Heavy Metals, and Rare-Earth Elements in Marine Sediment at Different Distance from the Indigirka River Delta

Studies have shown that the concentration of heavy carbon isotope in the organic matter (OM) in the surface layer of the marine sediment increases and the amount of terrigenous OM decreases by about 1.4 times with increasing distance from the Indigirka River delta from 50 km to 600 km. This is accompanied by 1.3-2.1 times decrease of heavy metals and 1.3-1.4 times decrease of rare-earth elements (REE). A strong correlation is observed between the contents of OM, heavy metals, and REE in marine sediments, with the exception of the Cd and W contents. At a distance of 50 km from the river delta, the heavy metals contents exceed their Earth's crust clarke values, while REE contents are higher than those of the North American Shale Composite (NASC). The opposite pattern is observed at a distance of 600 km from the river delta.