有机肥施用年限对菜地重金属累积迁移的影响

The Effect of Long-Term Application of Organic Fertilizer on the Accumulation and Migration of Heavy Metals in Vegetable Soil

集约化蔬菜生产系统中重金属的污染严重影响作物品质并威胁人体健康.为揭示菜地长期有机肥管理对土壤重金属累积迁移的影响,对进一步降低重金属风险提供指导,本研究以重庆市石柱县某典型辣椒大白菜轮作系统为研究对象,按照种植年限分为0年(林地)、1~3年、4~9年、10~15年,选取4个村庄的24块典型地块,测定了不同深度土壤中铁(Fe)、锰(Mn)、铜(Cu)、锌(Zn)、镍(Ni)、铅(Pb)、镉(Cd)、钴(Co)、铬(Cr)共9种重金属有效态质量分数和土壤pH值等,分析了土壤重金属有效态质量分数随种植时间与土壤深度的累积迁移规律,及其与有机肥年平均投入量和土壤pH值之间的相关性.研究表明,菜地土壤中有效重金属质量分数从大到小依次为Fe,Mn,Pb,Zn,Cu,Ni,Co,Cd,Cr.菜地有效态重金属质量分数随种植时间的增加而显著增加,与林地相比,菜地Fe,Mn,Pb,Zn,Cu,Ni,Co,Cd,Cr质量分数分别增加了353%,67%,130%,67%,218%,68%,110%,105%,88%.就不同土层而言,0~20 cm土层中重金属有效态质量分数显著高于下层(20~40 cm和40~60 cm)土壤重金属有效态质量分数,且Fe和Co元素呈现显著向下迁移的趋势.土壤有效态重金属的累积与有机肥年平均投入量呈正相关关系,与土壤pH值呈负相关关系.菜地土壤有效态重金属呈现逐年累积的趋势,且种植时间越长有效态重金属质量分数越高,0~20 cm是有效态重金属累积的主要土层,蔬菜生产中应降低有机肥投入所造成的重金属污染以及改良土壤酸化情况.

Heavy metal pollution in the intensive vegetable production seriously affects the crop quality and threatens the human health.To reveal the effect of organic fertilizer application on heavy metals accumulation and migration,and provide guidance for further reducing the risk of heavy metals,the research was conducted with 24 typical pepper-Chinese cabbage rotation crop system from 4 villages randomly selected in Shizhu County in Chongqing according to four terms of cropping years:0 years(forest land),1-3 years,4-9 years and 10-15 years.The soil pH value and the contents of iron(Fe),manganese(Mn),copper(Cu),zinc(Zn),nickel(Ni),lead(Pb),cadmium(Cd),cobalt(Co)and chromium(Cr)in different soil layers were determined.The results showed that the order of available heavy metal content in vegetable soil from high to lowwas Fe,Mn,Pb,Zn,Cu,Ni,Co,Cd,Cr.The content of available heavy metals in vegetable field increased significantly with the increase of planting time.Compared with forest land,the content of Fe,Mn,Pb,Zn,Cu,Ni,Co,Cd and Cr in vegetable fields increased by 353%,67%,30%,67%,218%,68%,110%,105%and 88%,respectively.In terms of different soil layers,the content of available heavy metals in the 0-20 cm soil layer was significantly higher than that in the lower layer(20-40 cm and 40-60 cm).The accumulation of available heavy metals in soil was positively correlated with the average annual manure input,and negatively correlated with soil pH.In the study area,the available heavy metals in vegetable soil showed severe accumulation tendency.The 0-20 cm was the main soil layer accumulation of available heavy metals.In vegetable production,the heavy metals pollution caused by application of manure should be reduced and soil acidification should be controlled.