贺江重金属污染对硅藻群落组成的影响

Diatom Assemblages Distribution along the Middle and Lower Reaches of Hejiang River in Relation to Heavy Metal Pollution

利用多元统计分析方法对贺江中游重金属污染的9个样点进行分析,研究了水质因子和重金属因子对硅藻群落的影响。冗余分析(Redundancy analysis,RDA)排序前两轴共同解释了硅藻群落变异程度的52%,RDA排序轴1与水质因子和重金属铊显著正相关,排序轴2与重金属铅显著正相关,单个环境因子的解释变量中,铊、硝氮、铅和氯化物的贡献量分别达到了21.8%、17.1%、12.6%和11.4%。偏冗余分析(Partial RDA)显示,水质因子和重金属因子分别解释了贺江中下游硅藻群落变异的48.2%、24.2%。利用方差分解的方法计算出单个硅藻种类对环境因子的解释程度,分析表明,Achnanthes minutissima、A.exigua Grunow、Nitzschia fonticola、N.tubicola Grunow是重金属因子喜好种,Cyclotella distinguenda、C.meneghiniana、Gomphonema parvulum、Navicula viridula var.rostellata、Nitzschia inconspicua、N.intermedia、Synedra ulna是水质因子的喜好种,Cyclotella atomus、Gyrosigma acuminatum、Melosira varians、Nitzschia palea等受两种因子的共同影响,分析结果与冗余分析具有一致性。结果表明,贺江中下游硅藻组成受水质因子和重金属因子的共同影响,水质起决定作用,重金属铊和水质硝氮是影响其组成的主要因素。

The distribution pattern of diatom assemblages in relation to water quality and heavy metal factor was investigated by redundancy analysis（RDA） and partial RDA. Nine sites were sampled along the middle and lower reaches of Hejiang River. The first two axes of redundancy analysis effectively explained 52% of species-environment variation. The first RDA axis was positively related to water quality and heavy metal element of Ti,the second RDA axis was significantly positively related to heavy metal element of Pb. The interpretation variable of Ti, NO3-- N, Pb, Cl was 21. 8 %, 17. 1 %, 12. 6 % and 11.4% respectively. Partial RDA analysis indicated that water quality explained a high proportion 48.2% of the variance,while heavy metal pollution explained 24.2%. Using variance partition method to calculate the single diatom explanation for water quality and heavy metal factors,the analysis showed that Achnanthes minutissima, A. exigua Grunow, Nitzschia fonticola,N. tubicola Grunow were preferred to heavy metal pollution, Cyclotella distinguenda, C. meneghiniana, Gomphonema parvulum, Navicula viridula var.rostellata, Nitzschia inconspicua, N. intermedia, Synedra ulna were likely to water quality factor,while Cyclotella atomus, Gyrosigma acuminatum, Melosira varians, Nitzschia palea were explained by the two factors together,the results were agreed with the RDA analysis. The results indicated that the distribution of diatom assemblages along the middle and lower reaches of the River was influenced by the two factors,the water quality was more important than heavy metal.