芦蒿中重金属铅、镉污染现状及溯源分析

Pollution status and traceability analysis of heavy metals lead and cadmium in artemisia selengensis

目的:掌握芦蒿中重金属铅、镉的污染现状,探讨其可能的污染来源,为芦蒿的种植管理及食品安全国家标准的制修订提供科学依据。方法:2017—2020年间连续4年在南京市12个区的种植环节、农贸市场、超市(或便利店)等场所采集芦蒿样本,在八卦洲不同方位芦蒿种植基地采集芦蒿样本及对应的土壤和灌溉用水样本,利用国家标准中规定的方法开展铅、镉含量检测。结果:检测铅、镉的芦蒿样本分别为501份和492份。铅、镉检出率分别为54.3%、98.8%,含量均值分别为0.16、0.082 mg·kg^(-1);不同采样场所芦蒿样本铅含量差异具有统计学意义(P<0.001),超市(或便利店)和农贸市场高于种植环节,镉含量差异无统计学意义;不同产地芦蒿样本中铅、镉含量差异均无统计学意义。芦蒿中铅、镉的超标率分别为10.8%和23.2%;不同采样场所芦蒿样本中铅超标率差异具有统计学意义(P=0.045),超市(或便利店)和农贸市场高于种植环节,镉超标率差异无统计学意义;不同产地(本地和外地)铅和镉超标率差异均无统计学意义。在八卦洲不同方位芦蒿种植基地共采集芦蒿及对应的土壤样本各50份,灌溉用水样本13份。所有土壤样本铅含量均小于农用地土壤污染风险筛选值,60%样本镉含量超过农用地土壤污染风险筛选值。土壤与芦蒿样本中铅、镉含量相关性均无统计学意义,土壤中铅含量与镉含量相关性具有统计学意义(r=0.792,P<0.001)。13份水样铅、镉检测值均小于检出限。结论:芦蒿中铅、镉污染较严重,尤其是镉污染;主要污染来源可能为芦蒿本身对土壤中铅、镉的富集,但销售环节芦蒿中铅还可能存在其他污染来源;有必要对芦蒿中铅、镉的污染限量值进行重新修订,尤其是镉限量值。

Objective:To master the pollution status of lead and cadmium in artemisia selengensis,explore its possible pollution sources,and to provide scientific basis for the planting management of artemisia selengensis and the formulation and revision of national food safety standard.Methods:From 2017 to 2020,artemisia selengensis samples were collected in growing part,farmers'markets,supermarkets(or convenience stores)and other places in 12 districts of Nanjing for four consecutive years.Artemisia selengensis samples and corresponding soil and irrigation water samples were collected in different directions of artemisia selengensis planting bases in Baguazhou.The contents of lead and cadmium were detected by the methods specified in the national standards.Results:501 and 492 samples of artemisia selengensis were detected for lead and cadmium,respectively.The detection rates of lead and cadmium were 54.3%and 98.8%respectively,and the average contents were 0.16 and 0.082 mg·kg^(-1) respectively.The difference of lead content in artemisia selengensis samples from different sampling sites was statistically significant(P<0.001).The lead content in supermarkets(or convenience stores)and farmers'markets was higher than that in planting links,and the difference of cadmium contents was not statistically significant.There was no significant difference in the contents of lead and cadmium in artemisia selengensis samples from different habitats.The over standard rates of lead and cadmium in artemisia selengensis were 10.8%and 23.2%respectively,the difference of lead exceeding standard rate in artemisia selengensis samples from different sampling sites was statistically significant(P=0.045).The lead exceeding standard rate in supermarkets(or convenience stores)and farmers'markets was higher than that in planting links,and the difference of cadmium exceeding standard rate was not statistically significant.There was no significant difference in the over standard rates of lead and cadmium in different producing areas(local and nonlocal).A total of 50 artemisia selengensis and corresponding soil samples and 13 irrigation water samples were collected in different directions of artemisia selengensis planting base in Baguazhou.The lead contents of all soil samples were less than the screening value of soil pollution risk of agricultural land,and the cadmium contents of 60%samples exceeded the screening value of soil pollution risk of agricultural land.There was no significant correlation of lead and cadmium between soil and artemisia selengensis samples,but there was significant correlation between lead and cadmium in soil(r=0.792,P<0.001).The detection values of lead and cadmium in 13 water samples were less than the detection limit.Conclusion:The pollution of lead and cadmium in artemisia selengensis is serious,especially cadmium pollution.The main pollution source may be the enrichment of lead and cadmium in soil by artemisia selengensis itself,but there may be other pollution sources of lead in artemisia selengensis during sales.It is necessary to revise the pollution limits of lead and cadmium in artemisia selengensis,especially the cadmium limits.