逐步判别分析法在海洋水质评价中的应用

摘要

To evaluate the marine water quality of West Guangdong Prcvince ,China ,an assumptive random sample comprising 400 stations (at each station there are 13 water quality indicators ) is established according to the Na-tional Water Quality Standards (GB 3097-1997) .The 13 indexes are filtered with a stepwise discriminant analysis method in terms of their water quality discriminant ability .Five indicators with distinguishing discriminant ability are picked out .T hey are a chemical oxygen demand ,oil ,cadmium content ,total phosphorus and total nitrogen .A discriminant function and a water quality classification plate are thereafter established with these five indicators . The method avoides introducing too many indicators to have adverse impact on the water quality evaluation model . T he above w ater quality classification plate is applied to evaluating the marine w ater quality of 40 stations in West Guangdong Province in 2010 .Compared with the result provided by Zhanjiang Oceanic and Fishery Environmental Monitoring Station ,it is found that the matching rate of 40 stations in this area is 95% .It indicates that the plate has a good application effect .It can be used as an effective way to evaluate the marine water quality by using multi-indicators .%针对粤西海域海洋水质评价这一问题，依照GB 3097-1997《国家海水水质标准》建立一个由400个站位组成、每个站位包含13个水质指标信息的假设随机样本，利用逐步判别分析法，在随机样本的13个水质指标中按其对水质分类判别能力的大小进行筛选，最终选出化学需氧量、石油类、镉、总磷、总氮这5个具有显著判别能力的指标，并利用这5个指标建立判别函数及水质分类图版，进而克服水质指标数据引入过多对水质评价模型的不利影响。利用上述水质分类图版对粤西海域2010年40个站位的水质状况进行了评价，对比海洋与渔业环境监测站的水质分类结果，其正确率为95％，说明该水质分类图版具有良好的实际应用效果，可作为解决利用多水质指标信息综合评价海洋水质这一问题的有效方法。