Features in REE and Methane Anomalies Distribution in the East China Sea Water Column: a Comparison with the South China Sea

Abstract—This paper presents review of dissolved Rare Earth Elements (REE) and methane anomalies distribution in the East China Sea water column. In general, the REE concentrations of the shelf water are markedly higher than those of Okinawa Trough water in the East China Sea. Rare earth elemental concentrations in the Okinawa Trough water mainly governed by the Kuroshio Current, along with particle scavenging processes and REE released from lateral transport. Hydrothermal vent activities also have their influence at some sites in the Okinawa Trough intermediate water. The result of comparison between dissolved REE in the East China Sea water with the South China Sea (known as Bien Dong or East Vietnam Sea) water shows that the dissolved REE contents of the South China Sea water are relatively similar to those of the slope water and the Okinawa Trough water and significantly lower than those of the continental shelf water in the East China Sea, except for the case of Ce. The South China Sea surface water may have the effects of fluvial and aeolian input, and coastal water masses at the deep-sea basin but less influenced than at the continental shelf. Both the East China Sea and the South China Sea contain methane gas emission sites, indicating deep fluid input into the seawater that influences the chemical composition of water masses, especially near the bottom water layer.