PFU微型生物群落监测中异养性指数的应用研究及其分形分析

The fractal analysis and application studies of hererotrophic index in PFU methods

对常德和汉江的异养性指数(HI)进行了分形分析,表明异养性指数在二维空间分布具有自相似性.异养性指数数据点与化学综合污染指数(P)数据点在双对数坐标中分段拟合时,当常德和汉江的LogP分别小于0 602和0 493时,常德和汉江的分形维数分别为0 39332和0 74110;当常德和汉江的LogP大于0 602和0 493时,常德和汉江的分形维数分别为0 30678和0 27239.拐点的出现表明异养性指数的变化在两个尺度域内遵从着不同的规律.拐点尺度以前,分维数较高,表明群落组成复杂,群落所受污染压迫较小.拐点以后,分维数较低,表明群落组成逐渐简单,群落所受的污染压迫较大.因此对异养性指数的分形研究,可以较好的反映微型生物群落在受到不同的污染压迫时,群落组成从复杂到简单演替过程中的动力学过程.另外,在水质微型生物群落监测方法(PFU)的4个生物参数中,除异养性指数外,其它3个参数都要求有原生动物分类基础,在显微镜下用活体鉴定种类,要求仔细观察,不能遗漏种类,对分析人员的技能要求高.但异养性指数(HI)靠仪器测定,易于掌握.

In this paper, heterotrophic index (HI) of Hanjiang River and water system of Changde City was analysed using fractal theory. Result showed that the dimension distribution of HI was selfsimilar. The data point of Log A (A= Heterotrophic index) and Log P ( P=Chemical Combined Pollution Index) were simulated gradually and the result of fractal analysis was as follows: when the Log P of Changde City and Hanjiang River was smaller than 0602 and 0493 , the corresponding fractal dimension was 0393 in Changde City and 0741 in Hanjiang River; when the Log P of Changde City and Hanjiang River was bigger than 0602 and 0493 , the corresponding fractal dimension was 0307 in Changde City and 0272 in Hanjiang River The occurrence of inflexion indicated that variation of HI in these two scale spectrum followed different disciplines: the fractal dimension is relatively higher before the inflexion, indicating more complicated community compositions and relatively lower pollution stress; the fractal dimension is relatively lower after the inflexion, indicating less complicated community compositions and relatively higher pollution stress. It is well known that the community compositions often evolve from complex to simplexes under pollution stress. And since the occurrence of the inflexion can reflect this kinetic process of community compositions, the fractal analysis of HI is valuble. In addition, to evaluate water quality using PFU methods, four parameters are generally used, but the computation of three parameters of them requires profound knowledge on protozoa classification, leading to practical difficulties. The only exception is HI, which can be measured using standard chemical methods. So compared to the other three parameters, computation of HI is both convenient and easy to grasp.