Analysis Of Heavy Metal Contents In Bryophytes, And The Impact Of Cr～(6+) To Partial Physiologic Index Of Mosses

Moss is a group of small high plant without real root and vascular system. It lies in the dark and wet environment and plays a very important to the nature. There are 23,000 moss species in the world and 2,100 are in China. Moss is one of the most sensitive indicators of atmospheric pollution. It has the characteristics of sensitivity,precision and directness etc, and unassailable high sorption and accumulating capacity to heavy metal dements in water or air. Therefore, the utilization of mosses as biomonitor of atmosphere had been widely applied in the world. However, this research is less in China and very important to strengthen the research.In the present study, the research analyzes the difference of the accumulating capacity to heavy metal in different mosses and the polluted degree of heavy metal in different sampling sites through the measuring of heavy metal in indigenous mosses in Chengdu City. Furthermore, the paper also studies on the impact of Cr⁶⁺ to partial physiologic index of Taxiphyllum taxirameum (Mitt.) Fleisch based on the above analysis. So it will provide scientific data for choosing appropriate moss as the indicator of environmental pollution and the biomonitoring of atmospheric heavy metal poolution.This paper is divided into three parts:The first part focuses on the determination of heavy metal contents in mosses. The result shows that in measuring of many elemental contents in moss, many measuring methods usually need to be provided because some elements have low contents, and others are high so as to single measuring method can not meet the measuring request simultaneity. The contents of eight elements (Cu,Mn,Fe,Zn,Cd,Cr,Ni,Pb) in Taxiphyllum taxirameum (Mitt) Fleisch. were measured by microwave digestion,ICP-AES and AAS. The accuracy and precision of the measured results were all good, and the contents of Pb measured by ICP-AES and AAS had no obvious difference (P＞0.05).The second part compares the difference of heavy metal contents among interspecies and intraspecies in mosses. The total contents of eight elements (Cu, Mn, Fe, Zn, Cd, Cr, Ni, Pb) determined by Inductively Coupled Plasma-Atomic Emission Spectrometery (ICP-AES) and Atomic Absorption Spectrophotometry (AAS) methods are compared among ten indigenous mosses, which are collected from four sampling sites in Chengdu City of China. Among these elements, the Fe concentration is the highest (5909.47μg/g), and Cd (1.56μg/g) the lowest. The comparison of most metal concentrations showes significant difference among interand intra-species, and T. taxirameum, E sinensis and B. argenteum accumulat greatly more than the others. ANOVA analysis indicats that the atmospheric pollution of heavy metal in Wangjiang park, Southwest Jiaotong University and the railway station area are more relatively serious than that of Ta Zishan park and Cultural park, and the concentrations of heavy metals in Chengdu City are higher than some foreign cities. By comparing the contamination factors of heavy metals in mosses, it is coincident with the previous conclusion that the difference of heavy metal depositions of mosses is not only related with environment, but also with their biological features.The third pat studies the impact of Cr⁶⁺ to partial physiologic index of T. taxirameum. The result indicates that the contents of chlorophyll and soluble protein in T. taxirameum decrease continuously under the heavy metal menace of five different strengths when the concentration of Cr⁶⁺ increases continously. At the same time, the activities of POD,ACT and SOD present the degressive trend with the Cr⁶⁺ strength insreasing. However, the activity of SOD has significant declining when the conten of Cr⁶⁺ is lower(5 mg/L); the activity of POD has also a obvious declining when the Cr⁶⁺ concentration is higher; the activity of CAT has no significant decreasing with the heavy metal concentration increasing. It also shows that T. taxirameum is very sensitive to heavy metal and a good indicator in monitoring environmental pollution.