Inorganic Speciation of Rare Earth Elements in Chaohu and Longganhu Lakes, East China

摘要

Inorganic speciation of dissolved rare earth elements (REEs) were calculated for Chaohu Lake and Longganhu Lake by using the program MINTEQ 2.30. The result shows that REE-Carbonate complexes, which account for more than 93 percent of total REE are the dominate and typically species in solution. Moreover, carbonator complexes (LnCO~(3+) ) were predicted to be the dominant species when pH between 7,2 and 8.0 and bicarbonate complexes (Ln (CO_3)~(2-) ) were predicted to be the dominant species when pH > 8.0. The free ion specie (i.e. , Ln~(3+) ) increases in these waters with pH decreasing and accounts for about 5.03 percent . The percentage of REE-phosphate complexes account for 1.61 percent of the dissolved REEs. REE-phosphate for light REEs complexes are supersaturated in Chaohu Lake and Longganhu Lake. Furthermore, LnP04 for heavy REEs are supersaturated in west of Chaohu Lake in high water period. PO_4~(3-) is responsible for limiting the dissolved REEs concentrations. REE-sulfate, REE-chloride, REE-fluoride and REE-hydroxide complexes, are negligible and generally account for less than percent of the total dissolved REEs.