湖北铜绿山古铜矿冶炼渣植被与优势植物的重金属含量研究

FLORA AND HEAVY METALS IN DOMINANT PLANTS GROWING ON AN ANCIENT COPPER SPOIL HEAP ON TONGLUSHAN IN HUBEI PROVINCE, CHINA

对已废弃 3 0 0 0余年的湖北铜绿山古冶炼渣堆进行了植被和土壤调查 .化学分析表明 ,冶炼渣的含Cu量极高 ,总量和有效态的Cu质量分数w(Cu)分别为 7789和 5 38mgkg-1.Cu的毒性是影响铜绿山植物自然定居的限制因子 .铜绿山现已形成了以草本植物为主体的良好植被 ,本次调查共记录有高等植物 2 8种 ,隶属 2 5属 15科 .优势种包括海洲香薷、蝇子草、鸭跖草、头花蓼、滨蒿、白茅和狗尾草等 7种植物 .植物分布与土壤中Cu含量有一定的相关性 ,鸭跖草分布区土壤中的Cu含量最高 ,白茅分布区土壤中的Cu含量最低 ,而其它 5种植物的分布区含Cu范围较广 ,平均在70 0 0mgkg-1左右 .除白茅、狗尾草和滨蒿外 ,其它 4种优势植物都有一定的Cu指示作用 ,尤其以这些植物的单优群落或者是它们的集合具有更高的指示价值 .本文首次报道鸭跖草是Cu的超富集植物 ,Cu2 +在地上部分 (DW )和根部(DW)的质量分数 (w)分别为 10 34和 12 2 4mgkg-1.而早期报道Cu超富集植物的海洲香薷则证明不是Cu超富集植物 .综合植物分布区土壤中的Cu含量和植物体的Cu含量 ,认为铜绿山海洲香薷、鸭跖草、蝇子草、头花蓼、滨蒿种群都是Cu耐性植物 ,可用于富Cu土壤如矿业废弃地的植被重建 ,而超富集植物鸭跖草可用于Cu污染土壤的植物修复 .表 4参 2

A field survey of soil and higher plants growing on an ancient copper spoil heap (3 000 years old) on Tonglushan in Hubei Province, China was conducted. Chemical analysis indicated the soils contained exceptionally high concentrations of Cu (total: w t=7789 mg kg -1; extractable: w ex=538 mg kg -1) and Fe, and relatively low concentrations of Pb, Zn, Ni, Cd and Cr. The phytotoxicity of Cu might be the limiting factor for plants natural colonization on the Cu spoil. 28 species belonging to 25 genera and 15 families were found growing on the spoil heap, including 7 dominant species: Elsholtzia haichowensis, Silene fortunei, Commelina communis, Polygonum capitatum, Imperata cylindraca var. major, Artemisia annua and Setaria viridis. In general, plant distribution had certain correlation will Cu content in soil. The soil grown with C. communis contained the highest levels of total and extractable Cu. That with E. haichowensis, S. fortunei and P. capitatum contained moderate or low concentrations of total and extractable Cu, while that with I. cylindraca and S. viridis contained the lowest amount of Cu. C. communis was newly identified as hyperaccumulator of Cu beacuse the w(Cu) in DW shoot and DW root of this species were 1 034 and 1 224 mg kg -1, respectively. It was also confirmed that E. haichowensis was not the Cu accumulator as earlier report. Results presented here indicated that E. haichowensis, S. fortunei, C. communis and P. capitatum were Cu indicators, and the monodominant association and assemblages of these species would be more confident in indicating Cu deposit. Tab 4, Ref 22