乐安河—鄱阳湖湿地植物群落特征及其优势植物对重金属Cu、Pb、Cd的富集

Plant community characteristics and the enrichment of heavy metals copper, lead and cadmium in the dominant plant species grown in the wetland of Lean River and Poyang Lake

关键词:  鄱阳湖  乐安河  湿地植物群落  优势种群  重金属  富集特性

Key words:  Poyang Lake  Lean River  wetland plant community  heavy metals  enrichment characteristics

摘要:

选择乐安河—鄱阳湖湿地典型植物群落,采用重要值方法评价各样点植物群落特征并筛选出典型优势植物,通过室内理化测试分析不同生境中优势植物植株及其根区土壤中重金属Cu、Pb、Cd的含量; 采用生物富集系数(BCF)方法评价不同优势植物对重金属Cu、Pb、Cd的富集特性。结果表明:研究区湿地植物以草本为主,在各样点共发现124种物种,包括蕨类植物2科2属2种,种子植物40科97属122种,并从中筛选出羊蹄、红蓼、鼠曲草、紫云英、苎麻等5种富集能力较强的优势植物; 植物根区土壤中的Cu、Cd含量均超过土壤环境质量三级标准,而且Cu、Cd的最高含量分别为824.03、5.03 mg·kg^-1; 不同优势植物对Cu、Pb、Cd等3种重金属元素中的1种或2种表现出较强的富集能力,其中优势物种红蓼对Cu具有较强的富集能力,含Cu量最高为148.80 mg·kg^-1,另一种优势物种鼠曲草对三种元素的生物富集系数均较高,且对Cd的最高富集含量为15.17 mg·kg^-1,对Cd的生物富集系数最高值为19.14,高于其他植物10倍以上,鼠曲草对重金属Cd 具有富集植物的基本特征,且对Cu和Cd具有共富集特征并具有较高的耐性,紫云英、羊蹄等对Cd的富集能力也较强。上述5种优势植物种群对鄱阳湖湿地Cu、Pb、Cd等重金属污染物的生态修复具有一定参考价值,可作为鄱阳湖湿地重金属污染修复植物的选择对象。

Abstract:

An investigation was conducted on the typical plant community and collected the soil and plant samples in different sampling sites in the wetland of Poyang Lake and Lean River. Plant community characteristics and the dominant plant community in different regions of Lean River were evaluated by using important value method. The contents of the heavy metals copper,lead and cadmium in the dominant plants in different habitats and the root zone soils were determined in the laboratory by using physical and chemical analysis methods, and the enrichment characteristics of heavy metals included copper,lead and cadmium in the dominant plants were evaluated by using bio-concentration factor(BCF)method. The results indicated that the main wetland plants were dominated by herbaceous plants in the sampling sites and 124 species in total were found in the different sampling sites, including 2 families, 2 genera and 2 species of ferns, and 40 families, 97 genera and 122 species of seed plants. In the survey sampling sites, Rumex japonicus, Polygonum orientale, Gnaphalium affine, Astragalus sinicus and Boehmeria nivea were the typical dominant plants which had strong enrichment ability of heavy metals. The heavy metals determined results indicated that the contents of copper and cadmium in some dominant plants' root zone soils exceeded the third class of the soil environmental quality standards. The highest content of copper in plant root zone soils was 824.03 mg·kg^-1 and the highest content of cadmium in plant root zone soils was 5.03 mg·kg^-1. And the five dominant species showed hyperaccumulation ability to one or two kinds of the heavy metal pollutants including copper, lead and cadmium. For example, Polygonum orientale had strong accumulation ability on copper and the highest content in P. orientale reached to 148.80 mg·kg^-1; another kind of dominant plant is Gnaphalium affine,the bio-concentration factor values of the three heavy metal elements were much more than those of other plants; the maximum cadmium content in G. affine was 15.17 mg·kg^-1 and the maximal value of bio-concentration factor value was 19.14,which was more than 10 times higher than those of other plants,which showed that G. affine possessed basic characteristics of accumulation on cadmium,and which also showed that G. affine had the characteristics of co-accumulation on copper and cadmium with higher tolerance, Astragalus sinicus and Rumex japonicus also possessed copper and cadmium co-accumulation characteristics. The five dominant plant species had certain reference values on the ecological restoration of heavy metals copper, lead and cadmium pollution on the wetland of Poyang Lake and Lean River.