栓皮栎林对城郊重金属元素的吸收和积累

A Preliminary Study on the Absorption and Accumulation in Oak ( Quercus variabilis) Stand in Suburb of Nanjing

研究了南京城郊下蜀林场次生栎林对重金属元素铅、镉、铬、镍的吸收和积累。结果表明 :栓皮栎林中金属元素在不同部位的含量变动范围分别是 0 .85～ 5.60 ,0 .0 1 1～ 0 .1 67,0 .35～ 2 .2 5,0 .90～ 3.90 μg/g ;林分重金属元素现存量分别 79.75,1 .92 ,2 1 .2 0 ,46.80mg/m2 ,根部存储最多 ,枝和叶占比例较小 ;栓皮栎林地表层土壤重金属元素含量较低 ,处于该类元素背景值的较低水平 ,属于洁净状况 ;栓皮栎对镉有富集作用。 48年生栓皮栎仍处于生长旺盛时期 ,重金属元素年吸收量分别是 1 3.79,0 .36,4.32 ,7.83mg/m2 ,其中归还量分别占 30 .56% ,2 1 .94% ,1 3.52 % ,2 9.3% ;在一个生长季内 ,栓皮栎林净积累的重金属铅、镉、铬、镍分别达到9.58,0 .2 82 ,3.74,5.54mg/m2 ;铅、镉、铬、镍元素的周转期分别是 1 9,2 9,36,2 0a。

Big trees had large interfaces with environment, so this dominant position was useful in accumulating heavy metals in highly residensed Nanjing areas. Based on the data of biomass, physical and chemical characters of soil in oak ( Quercus variabilis ) stand, the studies were carried out on the absorption and accumulation of heavy metals at Xiashu long term ecological monitoring station. The results showed that: in different organs of the oak, the contents of heavy metals were quite different, the ranges of them were Pb 0.85～5.60, Cd 0.011～0.167, Cr 0.35～2.25, Ni 0.90～3.90 (μg/g).The heavy metals storage in the oak was 79.75 for Pb, 1.92 for Cd, 21.2 for Cr and 46.80 for Ni (mg/m 2), respectively.The urban forest soil in Nanjing areas was under a very clean condition, owing to forests function of protecting and accumulating airboral depositions. The biological cycles of the elements were described as : annual uptake, Pb 13.79, Cd 0.36, Cr 4.32, Ni 7.83 (mg/m 2) ; annual retention, Pb 9.575, Cd 0.282, Cr 4.32, Ni 5.535 (mg/m 2); annual return Pb 4.21, Cd 0.079, Cr 0.58, Ni 2.29 (mg/m 2) ; turnover period Pb 19, Cd 29, Cr 36,Ni 20 (year).