不同水域鲤鱼耳石CaCO3晶体结构特征与环境响应初探

鱼耳石主要成分是CaCO3,主要以文石(或霰石)形式存在,在过去四、五十年来在晶体结构研究方面取得了较多的成果.然而,不同水域鲤鱼耳石CaCO3晶体结构信息特征与环境响应研究却未见报道.本文对密云水库和白洋淀水域鲤鱼耳石X-粉晶衍射结果进行了研究,并分析了两地晶胞参数a0、b0、c0和单位晶胞体积的差异.结果显示,两地耳石样品均由霰石组成,分属三种不同结构:两种六方晶系P63/mmc(no.194)结构和一种斜方晶系Pbnm(Pnma no.62)结构.属于六方晶系的耳石样品中,密云水库鲤鱼耳石样品晶胞参

A Tentative Discussion on the CaCO3 Crystal Structures of Otoliths and the Environment Response in Different Water Areas

Otolith of fish is made of CaCO_3,and its crystal form is aragonite or vaterite.In the past forty or fifty years,quite a few achievements have been made in the study of the CaCO3 crystal structures in the otoliths,but no advances in the researches on therelationships between the features of the crystal structures of the fish otoliths and their living environments have been reported in literature.In this paper,the characteristics of crystal structures of CaCO3 in otoliths of carps from two areas with extremely different water environments,i.e.,the seriously polluted Baiyangdian shallow lake and the Miyun reservoir,were studied by means of X-ray diffraction analysis,and the basic cells and dimensions were analyzed.The experimental results indicate that all samples from the two sites are composed of vaterites,which can be divided into three different crystal structures,namely,two types of hexagonal cells with space group P63/mmc and one type of orthorhombic cell with space group Pbnm.For the vaterites with the hexagonal cell,the dimensions of samples from the Miyun reservoir are much nearer to the standards than those from the Baiyangdian shallow lake,and a0 of the former is relatively bigger than the latter,but things are opposite for c0.Moreover,the cell volume of vaterite from the Miyun reservoir is bigger than that from the Baiyangdian shallow lake,and the former is nearer to the standards than the latter.There exist no distinct results for the vaterites with the orthorhombic cell.The results of microchemical characteristic composition analysis show that the differences in the dimensions of basic cells of vaterites from the two localities are consistent with those in the microchemical characteristic compositions of vaterites from these localities.Therefore,the information of the crystal structure of vaterite in otolith of carp seems sensitive to water quality and water environment,and this can be regarded as an important indicator to the pollution degree of the water.