4:30 PM - 4:45 PM
[AHW22-22] Natural attenuation of zinc by the sediment layer in Majuro Atoll
Keywords:Freshwater lens, Groundwater, Fixation, Zinc
These results suggested that Al in Majuro Atoll was of airborne origin. The enrichment factors (EFs) of the elements normalized to Al concentration of continental crust showed that REEs were also transported as dust. The EFs of Zn and Cu were greater than 21.1 and 5.45, respectively, suggesting that Zn and Cu were mainly of anthropogenic origin. The speciation analysis of Zn and Cu by K-edge X-ray absorption near-edge structure (XANES) showed the presence of Zn–Cu alloys originated from industrial products. It was also revealed that Zn was enriched in the surface due to anthropogenic emission after urbanization on Majuro Atoll and fixed by carbonate and phosphate at the upper layer, which inhibits migration of Zn into the deeper layer and its release to the groundwater and coastal water.
Hence, the fixation of heavy metals at the surface prevents their exposure to aquatic organisms and residents via fresh groundwater in the island.