南坑河污染初步调查及河岸植物的富集能力

Heavy-Metal Contamination at the Nankeng River and Phytoaccumulation of Riparian Plants

南坑河是新丰江的一条支流,直接汇入广东省最大的饮用水源地新丰江水库。野外调查中发现私自采矿和在河流沿岸洗矿等行为不断发生,大量洗矿废水未经处理直接注入南坑河,可能会造成污染。因此,采样初步分析了南坑河河水、河流底泥沉积物及附近优势植物的9种重金属元素含量。结果发现：与地表水II类标准相比,南坑河枯水期水体污染严重,其中连续2 a的铅、砷和汞超标,超标倍数分别为1.7~1.8、1.3~1.9和1.6~2.9倍,而底泥中铜、镉、铅、锌和砷均超标,超标倍数分别为4.8、9.0、3.9、4.3和10.9倍,镉和砷超标较为严重。另外,收集并鉴定了河岸或河漫滩中天然生长的15种植物,发现以蕨类植物和多年生禾草为主要类型。通过分析植物体内9种重金属元素含量,发现对砷吸附能力最强的当属蜈蚣草,其叶片中砷的含量（609.20 mg/kg）和茎干中砷的含量（814.77 mg/kg）均大于根部的砷含量（577.30 mg/kg）;蜈蚣草对铁、锰、铜和铅的吸附能力也远远大于其他河岸植物,可以作为良好地修复以砷为主的复合重金属污染土壤的富集植物。

The Nankeng River,a branch of the Xinfengjiang River,directly flows into Xinfengjiang reservoir,which is the largest drinking water source in Guangdong Province.During the field survey,waste water without treatment was inflooded the Nankeng River due to lawless mining.So 9 common pollutants,Fe,Mn,Cu,Zn,Pb,Cd,Cr,as and Hg,were determined in the water and sediments of the Nankeng River.The results showed that water was contaminated seriously in low water period.In 2011 and 2012,the contents of Pb,As and Hg in water were 1.7-1.8,1.3-1.9 and 1.6-2.9 times over the second grade of drinking water quality standard,respectively,while those of Cu,Cd,Pb,Zn and As in sediments were 4.8,9.0,3.9,4.3 and 10.9 times,respectively,over the soil quality standard.Otherwise,the riparian plants from Nankeng River were collected and identified,and 15 plant species,dominated by fern and perennial grass,were found.The 9 common pollutants in plants were also examined,and the results indicated that Pteris vittata was not only an arsenic-accumulating plant,but also a compound-accumulator,which can be used in the soil remediation of multiple contamination.