绿篱阻隔公路粉尘铅和镉污染茶园的研究

Studies on Obstructing Effect of Hedge on Pollution of Lead and Cadmium Stive above Driveway on Tea Plantation

选择距离浙江省松阳县新兴镇茶鲜叶市场3km的一段乡镇级别公路,路两边都是茶园。在路的一侧连续密植3段200m长、高度分别为1.5m、2.0m和3.0m小松树为绿篱,紧接着的200m路段不植树作为CK。在设置绿篱前和1.5年之后,检测嫩梢、成叶和表土层的铅、镉含量。结果表明:设置绿篱前,1芽1叶嫩梢、成叶和表土层的铅含量在路边为0.66~0.75mg/kg、3.11~3.40mg/kg和25.86~27.11mg/kg,在50m处为0.55~0.71mg/kg、2.11~2.42mg/kg和24.96~26.28mg/kg,在100m处为0.51~0.66mg/kg、1.72~1.78mg/kg和23.12~26.24mg/kg。种植绿篱1.5年之后:(1)1芽1叶嫩梢和成叶铅含量:在种植3.0m高绿篱的路边下降18.6%和27.4%,在种植2.0m高绿篱的路边下降8.5%和7.5%,在种植1.5m高绿篱的路边下降6.2%和4.2%;(2)绿篱区距离路边50m、100m和200m处,1芽1叶嫩梢和成叶铅含量也相应地有微量递减,相应地,CK区50m、100m和200m处嫩梢和成叶的铅含量略微增加;(3)1.5m、2.0m和3.0m高绿篱的路边表土层铅含量下降1.7%、2.9%和3.2%,CK区则升0.37%。公路粉尘的镉对于茶叶的污染不甚明显。分析认为:车流量很大的乡镇公路粉尘中铅元素对路边茶园有一定污染,尤其是距路边0~50m范围,路边设置3m高绿篱则对于铅和镉有明显的阻隔作用。

A segment of driveway at township specifications,being 3 km distant from the fresh tea foliage marketplace of Xinxin Town of Songyang County in Zhejiang Province,was chosen,whose both roadsides connected tea plantation. On the one roadside,three consecutive 200 m length of sections were grown with little pine trees,in turn at the height of 1. 5 m,2. 0 m and 3. 0 m. And the pine trees acted as hedge. The adjoining 200 m section was not grown with pine trees,as CK. Before and 1. 5 years after setting up the hedge,plucked the shoots,the adult leaves and topsoil and detected their contents of both lead and cadmium. The results showed that before establishing hedge the contents of lead in tender shoots with 1 bud and 1 leaf,adult leaves as well as topsoil were 0. 66 ~ 0. 75 mg/kg,3. 11 ~ 3. 40 mg/kg and 25. 86 ~ 27. 11 mg/kg on the roadside,0. 55 ~ 0. 71 mg/kg,2. 11 ~ 2. 42 mg/kg and 24. 96 ~ 26. 28 mg/kg and 23. 12 ~ 26. 24 mg/kg at 50 m from the roadside,0. 51 ~ 0. 66 mg/kg,1. 72 ~ 1. 78 mg/kg and 23. 12 ~ 26. 24 mg/kg at 100 m from the roadside,respectively. 1. 5 years after establishing the hedge:(1) on roadside the contents of lead in tender shoot with 1 bud and 1 leaf and adult leaves of tea plants under 3 m high hedge reduced by 18. 6% and 27. 4%,under 2 m high hedge by 8. 5% and 7. 5%,under 1. 5 m high hedge by 6. 2% and 4. 2%;(2) the contents of lead in tender shoot with 1 bud and 1 leaf and adult leaves a little decreased progressively from 50 m to 200 m from the roadside; accordingly,those in CK area a bit increased progressively from 50 m to 200 m from the roadside;(3)The content of lead in topsoil on roadside with 1. 5 m,2. 0 m and 3. m high hedge reduced by 1. 7%,2. 9% and 3. 2% respectively; however,that in CK area went up by 0. 37%. The pollution of cadmium in stive above the driveway on tea foliage was not very obvious. It was considered that lead in stive above the driveway with large vehicle flowrate in countryside polluted the wayside tea plantation to some extent,especially 0 ~ 50 m extent to roadside; the hedge on the roadside evidently obstructed both lead and cadmium in stive above the driveway.