污灌区农作物中重金属分布特征与成因分析——以太原市某灌区为例

Distribution Characteristics and Cause Analysis of Heavy Metals in Crops in Sewage Irrigation Area

以近50年污水灌溉历史的太原市某污灌区为研究区,随机采集13种农作物样品,其中,包括3种粮食样品(高粱、玉米和大豆)和10种蔬菜样品(芹菜、香菜、茼蒿、小茴香、葱、番茄、辣椒、黄瓜、茄子和扁豆)。对采集的农作物的根、茎、叶和果实样品中重金属Co、Ni、Cu、Zn、Cd和Pb的含量进行了分析,并对照当地土壤重金属污染情况进行了成因分析研究。结果显示,重金属在农作物中的平均残留量由大到小依次为Zn>Cu>Ni>Pb>Co>Cd,平均残留量依次为12.001、9.121、1.818、0.955、0.257、0.023 mg/kg;农作物最富集重金属的部位是根,其次是茎和叶,最后是果实;小茴香根部的Ni和叶部的Pb分别超过无公害蔬菜重金属物质限量标准的5.87和7.30倍,大豆中根中的Cu和高粱根中的Pb分别超过粮食类检测卫生标准限值标准9.25和15.40倍。同时,蔬菜的重金属污染与当地土壤重金属污染存在一定联系,该污灌区农作物中重金属的富集主要是由于常年的污水灌溉导致的重金属在土壤中的富集而产生的。

Based on the investigation of heavy metals （cobalt, nickel, copper, zinc, cadmium and lead） in some popular crops, the contents of the six heavy metals were detected in different parts of 13 kinds of crops base in one sewage irrigation area of Taiyuan ,which had 50 years history of irrigation,including three kinds of grain crops （ broomcorn, corn and soy bean） and ten kinds of vegetables （ celery, parsley, garden chrysanthemum, common fennel, onion, tomato, peppers, cucumber, eggplant and lentil）. In order to analyze heavy metals pollution in vegetables,the investigation on heavy metals in soils was also carried out in study field. The results showed that the order of contamination followed Zn 〉 Cu 〉 Ni 〉 Ph 〉 Co 〉 Cd, the average contents were 12. 001,9. 121, 1. 818, 0. 955, 0. 257 and 0. 023 mg/kg respectively. The order of contents of heavy metals in different parts of crops was root 〉 stem and leaf 〉 fruit. The contents of Ni and Pb in the root of garden chrysanthemum were 5.87 times and 7.3 times higher than the national standard respectively. The contents of the Cu in the root of soy bean and the Pb in the root of broomcorn were 9.25 times and 15.4 times higher than the national standard respectively. The contents of heavy metals in vegetables were affected greatly by soils. The enrichment of heavy metals in the crops was mainly because of years of wastewatcr irrigation in soil. It was necessary to focus on potential risk of heavy metals for food safety and human＇s health in agricultural soils and vegetables in this sewage irrigation area.