Qiong Wu

and 8 more

Dissolved rare earth elements (REE) and neodymium isotopic compositions (εNd) were intensively used to evaluate water mass mixing and lithogenic inputs in oceans. The South China Sea (SCS) is the largest marginal sea and a key region for reconstructing past hydrological changes in the West Pacific; however, its REE and εNd distribution are still not well established. This study investigated dissolved REE concentration and εNd distribution at four water stations in the northern and central SCS to better constrain the εNd distribution and REE cycle in the SCS. The results show relatively high concentrations of REE in surface seawater due to the terrigenous inputs. Seasonal variability in the middle REE enrichment is observed, suggesting a controlling role of the lateral mixing of water masses in the REE fractionation. The decreased REE concentrations in bottom water are mainly attributed to the re-suspended particle scavenging. Surface seawater εNd varies from -2.8±0.3 to -6.7±0.3, implying a significant modification due to riverine inputs. The intermediate water is characterized by a slightly negative εNd compared to the North Pacific Intermediate Water (NPIW) suggesting a vertical mixing between the intermediate and deep water within the SCS. εNd of deep water shows a narrow range from -3.4±0.3 to -4.2±0.3 (mean value of ~-3.8), supporting the presence of Pacific Deep Water (PDW) in the deep SCS basins nowadays. εNd of deep water in the SCS behaves conservatively along its pathway from the West Pacific to the SCS even though particle scavenging occurs in bottom water.