A Study On Enrichment Of Rare Earth Elements In Intertidal Zone And Their Ecological Effects From Northern Hainan Island

Intertidal zone is the belt between land and ocean，its environment and ecosystems wereaffected by the land and ocean.Based on wetland of Dong zhai port，Qing lan port and Xin ying port on northern Hainanisland. conducting geochemical analysis and research on rare earth elements (REE) of wetlandsediments，discusses the composition and differentiation features of of rare earth elements inthe sediment，analyzing rare earth elements composition of mangrove plants，and conductcomparative study with rare earth elements in sediments，to discuss the shifting law of rareearth elements in the sediments and plants.The main conclusions can be summed up as follows:1. The∑REE value of sediments is between71.79ug/g-489.36ug/g，with a average valueof276.76ug/g，higher than average value of soil in China，acidic soil in South China and rareearth elements in the earth’s crust. The average∑REE value of available state is17.10ug/g，higher than the average value12.0ug/g of available state in soil in China.The average ratio∑LREE/∑HREE in sediments is5.54，available contents of∑LREE/∑HREE is3.78.Itindicated that both sediments and rare earth elements of available state in the area，rare earthand heavy rare earth elements have obvious differentiation，rare earth elements are rich.2. On the vertical space，sediments of rare earth elements in different profile haveobvious differences. In Dong zhai port，∑REE value of surface sediment (258.57ug/g)<∑REE value of deeper sediments (293.39ug/g)，∑REE value (13.74ug/g) of available statein surface layer <∑REE value of effective state in deeper layer (23.76ug/g)；In Dong zhaiport，∑REE value of surface sediments（266.24ug/g）>∑REE value of deeper sediments（178.02ug/g），And∑REE value of surface effective state（11.00ug/g）<∑REE value ofdeeper effective state（12.81ug/g）；In Xin ying port∑REE value of surface sediments（297.17ug/g）<∑REE value of deeper sediments（341.02ug/g），∑REE value of surfaceeffective state（19.91ug/g）<∑REE value of deeper effective state（21.37ug/g），Average valueof rare earth elements and heavy rare earth elements have the same change rule in differentwetland distribution and rare earths.3. The partition curves of sediments in the research area and Hainan island basalt laterite materials’s REE overall similar，but the value of REE in the sediments in the research area issignificantly higher than the content of REE in Hainan island basalt laterite materials. Itindicated that sediment provenance mainly comes from the basalt laterite materials，the rareearth elements are rich at the same time.4. The change values of δEu is between0.51and0.90，with an average of0.68， are lessthan1.05，the expression is negative anomaly，has Eu loss phenomenon. The change value ofCe is between1.61and2.37，with an average of1.86，the overall are characterized by positiveanomaly，Ce is relatively rich.5. The average activation coefficient range of rare earth elements in sediments of Dongzhai port，Qing lan port and Xin ying port is0.05-0.13、0.04-0.10、0.05-0.14respectively.Dyactivation coefficient is the highest，to an average of0.12. Ce activation coefficient0.05is thelowest. The variation coefficient range of rare earth elements is0.31-0.40，the range of changeis stable.6. Aegiceras corniculatum and Ceriops tagal have the strongest transfer ability of rareearth elements，xylocarpus granatum and Scyphiphora hydrophyllacca have the weakesttransfer ability of rare earth elements. Seven plants in the research area have weak transferability of Ce、Pr、Nd、Sm、Gd、Dy、Yb、Y element. The ecological restoration work ofmangrove wetland should cultivate more plants of strong transfer ability for these elements inthe future.