Study Of The Coupling Relationship Between Micro-CT Character Of Carp Otolith And The Heavy Metals In Waters

Otolith becomes a good environmental information carrier because of the biological inertia, and can objectively record the historical changes in the water environment and the enrichment of low concentrations of pollutants. At present, the research which otolith is used for the water quality evaluation and dynamic monitoring of lakes is mainly based on the micro-chemical analysis of the water body and otolith at home and abroad. It is necessary to find out some simple and sensitive typomorphic characters which can confirm there are some coupling relationship between otolith and the water quality.This paper studies carp otolith from the Baiyangdian and the Miyun Reservoir whose water quality are different. X-ray tomography (CT) and Micro-CT technology are first applied to the study of the response relationship between carp otolith and the heavy metals in the water, while XRD, SEM, LA-ICP-MS techniques have been used to the study of otolith phase, structure, morphology and elemental enrichment. The author clearly observe daily growth rings and the growth ring boundary of sagittae under SEM; Micro-area XRD showed there is no overall difference in mineral species and crystal structure of otolith from the different waters, but there is a slightly different about lattice parameters, lattice parameters a of the lapillus is smaller than the standard lattice parameters in the Baiyangdian, while lattice parameters c of the sagittae is bigger than the standard lattice parameters; LA-ICP-MS analysis revealed that the contents of Cu and Pb of otoliths in Baiyangdian are higher than the contents of corresponding elements of otoliths in Miyun reservoir, the content of Mg of otoliths in Miyun reservoir is higher than the content of otoliths in the Baiyangdian; Micro-CT experimental data shows that the Micro-CT value of otolith from the Baiyangdian is higher than that r from the Miyun Reservoir.Comprehensive analysis shows that: the water quality will not affect polymorph of calcium carbonate in otolith basically, but a slight impact on lattice parameters, Mg and the heavy metals Cu and Pb led to aberration of lattice parameters of calcium carbonate. The contents of Cu and Pb is the main factor to the the difference of Micro-CT value of otolith from different waters. The contents of Cu and Pb which have a high atomic number are higher in otolith from the Baiyangdian waters, resulting of the high density voxels. Cu and Pb have the characters: high atomic number, high electronic binding energy ,high density and the atomic structure is tightness .The X-ray collides with Cu and Pb and can be absorbed largely when the X-ray irradiate the otolith, which led to large absorption coefficient and the high value of Micro-CT. To sum up, information on heavy metals with high atomic number in the carp otolith can be reflected by statistical comparison of Micro-CT data. Elements in otoliths have the similar distribution trend with elements of the waters and can be obviously enriched. Therefore, there is the coupling relationship between Micro-CT character of carp otolith and the heavy metals in waters, which can be used to direct the information of the heavy metals in waters as typomorphic character.