七项河流附着硅藻指数在东江的适用性评估

综合运用因子分析、聚类分析、箱型图分析等统计方法评估了河流附着硅藻生物指数(Biological Diatom Index,IBD)、硅藻营养化指数(Trophic Diatom Index,TDI)、斯雷德切克指数(Sládecˇek’s Index,SLA)、特定污染敏感指数(Specific Polluosensitivity Index,IPS)、硅藻属指数(Generic Diatom Index,IDG)、戴斯指数(Descy Index,DESCY)和欧盟硅藻指数(European Economic Community Index,CEE)在东江流域河流水质评价中的适用性。结果显示:SLA与IPS,CEE显著相关(P<0.05),CEE与TDI不相关,其余指标间均极显著相关(P<0.01)。SLA与13项水质理化指标均无相关性,TDI与含氯度(Cl)显著负相关,CEE与溶解氧(DO)、电导率(Cond.)、总氮(TN)显著正相关(P<0.05),其余指标与氨氮(NH4-N)、pH不存在线性相关,与五日生化需氧量(BOD5)、高锰酸盐指数(CODKMnO4)、亚硝氮(NO2-N)、硝氮(NO3-N),总磷(TP)具极显著相关性(P<0.01)。13项水质理化指标中主成分负荷贡献大于50%的八项理化参数DO、BOD5、CODKMnO4、TN、NO3-N、NO2-N、TP和SiO2将试验区水质分为四组。IPS、IBD、IDG和CEE与水质物化分类一致性较好。IPS、IBD、IDG和CEE的逐步判别分析(引入P=0.20,剔除P=0.25)显示IPS和CEE都只选出了NO2-N,分类判别的正确率分别为55.6%和48.1%;IBD引入了NO2-N,CODKMnO4和DO 3个解释变量,判别正确率74.1%;IDG引入BOD5和NO3-N两个变量,分组正确率63.0%。硅藻群落聚类显示,IBD和IDG在水质物化分类的箱型图中呈现出明显合理的趋势。以上研究表明IBD和IDG硅藻指数最适合用于东江河流水质生物监测与评价。

Exploration of benthic diatom indices to evaluate water quality in rivers in the Dongjiang basin

Benthic diatoms are considered one of the most suitable organisms in bioassessment of water quality because of their high sensitivity to water temperature, nutrients, organic pollution and heavy metals. Since the 1970s, a number of indicator indices have been developed and used for the assessment of river quality including the IBD (Biological Diatom Index), TDI (Trophic Diatom Index), SLA (Sládeček's Index), IPS (Specific Pollution Sensitivity Index), IDG (Generic Diatom Index), DESCY (Descy Index) and CEE (European Economic Community Index). However, it is still not clear whether the ecologic signature of diatoms differs between these indicator indices. Moreover, in China, river water quality monitoring is usually limited to physi-chemical variables, which provide a snapshot picture of chemical characteristics at the time of sampling. Assessment of diatoms has the advantage that their observed status is a reflection of water quality conditions over a period of time prior to sampling.The Dongjiang River basin, as one of the main river systems in the Pearl River Basin, provides significant ecosystem services, such as drinking water, electricity supply, transport, irrigation water supply, fishery.In this study, seven diatom indices (IBD, TDI, SLA, IPS, IDG, DESCY and CEE) were tested to evaluate the water quality of rivers in the Dongjiang basin by means of correlation coefficient analysis, factor analysis, cluster analysis, box plot analysis and discriminant analysis. Pearson correlation coefficient analysis showed that IPS, IBD and IDG were closely related, and IPS, IBD, IDG and CEE had significant correlation with BOD₅, COD_KMnO4, NO₂-N, NO₃-N. IPS, IBD, IDG and CEE gave better performance in comparison of the seven diatom indices characterized for different water quality groups sorted by 8 key physicochemical variables (DO, BOD₅, COD_KMnO4, TN, NO₃-N, NO₂-N, TP and SiO₂) indentified by factor analysis. Results from stepwise discriminant analysis (P to entered= 0.20, P to removed= 0.25) were represented as follows: for IPS and CEE, NO₂-N was the only selected variable, and the correction percent was low by 55.6% and 48.1%. The discriminant analysis selected NO₂-N, COD_KMnO4 and DO for IBD, and the correction percent was up to 74.1%, IDG was discriminated by two variables (BOD₅ and NO₃-N), and the correction percent was 63.0%. IBD and IDG showed clear and reasonable trend in the box plots with water quality groups clustered from the diatom communities. This study suggested that the diatom indices can be applied for monitoring rivers in the Dongjiang basin, especially IBD and IDG.