水葫芦(Eichhornia crassipes)基质中铜残留对蔬菜生长和食用安全的影响

摘要

To harvest and compost water hyacinth and then use it as a component of the medium in soilless culture is a no-vel train of thought to turn waste into resource. However, as the wastewater from aquacultural farms generally contains heavy metal pollutants, like Cu, and so does the plant growing in the wastewater, it is necessity to assess impacts of the culture media contain in composted water hyacinth on growth and food safety of the vegetable in soilless culture. Results show that in media with Cu varying in the range of 0-600 mg·kg-1 growth of radish and water spinach were not signifi-cantly affected, and Cu concentrations in the edible parts of the two vegetables were within the safety limits ( 10. 0 mg· kg-1 ) set in the National Standard for Food Safety of China, but a relatively higher Cu concentration, about 15 mg·kg-1 , in roots of the water spinach was detected. The concentration of Cu was significantly lower in the edible parts of radish ( 0. 2-1. 6 mg·kg-1 ) than in those of water spinach ( 0. 5-4 mg·kg-1 ) . The content of Cu in the plants was found to be significantly related to the content of exchangeable Cu in the growing media. So it is much safer to plant radish than water spinach in soilless culture using composted water hyacinth in the medium. It is, therefore, essential to consider not only content and availability of Cu in the soilless culture medium, but also species of the vegetable to plant and characteristics of their biological Cu absorption in assessing potential risk of heavy metal pollution of the culture medium to food safety.%将修复养殖水体中收获的水葫芦堆置发酵后作为基质材料是资源化利用的新思路,但由于养殖废水中普遍存在重金属如Cu的污染问题,因此资源化利用的关键是重金属对蔬菜生长的影响和食用安全问题.研究结果表明:基质中w(Cu)在0~600 mg·kg-1范围内对萝卜和空心菜的生长没有显著影响,而且其可食部分未超出GB 15199—1994《食品中铜限量卫生标准》中Cu含量的安全限量标准(10.0 mg·kg-1);但基质中w(Cu)>600 mg·kg-1时,空心菜根系中w(Cu)偏高(15 mg·kg-1左右).空心菜可食部分w(Cu)(0.5~4 mg·kg-1)显著高于块根类的萝卜(0.2~1.6 mg·kg-1);2种蔬菜体内Cu含量与基质中可交换态Cu具有显著相关性.相同条件下,种植块根类萝卜的安全性比须根类空心菜要高.在评估基质中重金属污染对农产品食用安全的风险时,不仅需要考虑基质中重金属含量及其有效性,还要考虑蔬菜种类及其生物学吸收特性.