上海市郊大气干、湿沉降对叶菜的污染效应及其健康风险评价

发布时间：2018-05-25 03:26

本文选题：上海市郊 + 大气沉降　；参考：《华东师范大学》2017年硕士论文

【摘要】：蔬菜中含有多种人体所必需的维生素、糖类、膳食纤维和矿物质等营养成分,在人们膳食中占有重要比例。近年来,食品中重金属超标事件频频发生,因重金属含量超标而引发的食品安全问题受到了广泛的社会关注。为此,2017年2月,国务院印发的《"十三五"国家食品安全规划》,强调加强耕地重金属污染治理并明确要求严格实施从农田到餐桌的全链条监管。重金属作为一种无机污染物质,具有高富集、低迁移的特点,严重威胁自然生态环境安全和人类健康。在蔬菜的生长环境中,土壤、水和大气中的重金属污染,会妨碍蔬菜的正常生长发育,且环境中的重金属会在蔬菜体内积累,由食物链进入人体,威胁人体健康。上海市郊地区蔬菜生产基地和零散农田为上海居民供应了大量蔬菜,由于大气沉降、污水灌溉、土壤质量不达标等原因,这些蔬菜面临着严重的重金属污染风险,存在潜在安全隐患。本研究选取上海市郊为研究区域,以Cu、Zn、Pb、Cd、Hg和As六种重金属元素作为主要研究指标,通过大气颗粒物采样和蔬菜的无土栽培模拟实验相结合,系统分析大气沉降对蔬菜重金属的影响。并通过室内干、湿沉降模拟实验,系统地研究蔬菜叶片施用重金属对蔬菜根部及可食部分的贡献率,揭示重金属被蔬菜叶片吸收后,在蔬菜内部的迁移转化过程。分析研究区域大气颗粒物的含量水平,大气颗粒物PM2.5的重金属污染水平;评价施加于叶片不同浓度重金属后蔬菜根部与可食部分的污染水平,以期探索研究区大气沉降与蔬菜重金属污染对人体健康的综合影响。利用无土栽培技术模拟重金属减少根系吸收的影响,完善在自然状态下,蔬菜叶面对大气沉降重金属吸收的机理研究。主要得出以下结论:(1)闵行区PM2.5中重金属元素Cd、Cu、Pb、Zn、Hg和As的平均质量浓度分别为0.49、5.78、17.89、188、0.0104和2.62 ng m~(-3)。不同重金属元素从大到小排序依次为ZnPbCuAsCdHg。健康风险模型计算出闵行区大气PM2.5中重金属经呼吸途径进入人体的年均超额危险度由高到低依次为AsCdPbZnCuHg。对不同人群的危险度对成年男性最高,依次为成年女性和儿童的1.15和1.5倍。(2)大气暴露及室内模拟种植蔬菜实验表明,室内四种蔬菜可食部分中所有元素含量均在标准限值内,大气暴露四种蔬菜Zn、Cd、Cu和As的含量也均小于国家标准规定的蔬菜重金属污染限值。室内模拟蔬菜生长环境较好,重金属含量低,而室外大气暴露条件下蔬菜重金属含量部分超标,其中Pb和Hg超标率为100%。室外大气暴露环境下水培种植的蔬菜可食部分的重金属含量普遍高于室内模拟,表明大气沉降中的重金属对蔬菜具有显著的影响。水培蔬菜的根部六种重金属含量均比较低,属于安全范围。蔬菜可食部分的Cu、Zn、Pb和As与根部对应的重金属呈现出明显的相关性。(3)在干、湿沉降条件下,四种蔬菜叶片对根部重金属富集系数从大到小排序相同,依次为空心菜、油麦菜、青菜和白菜。干沉降对大部分蔬菜的可食部分和根部中的Cu、Cd和As污染效应更大;而Zn、Pb和Hg则相反。总体上,干、湿沉降对于六种重金属的干、湿沉降条件下蔬菜重金属浓度与空白组浓度的比值从到大小排列为AsHgPbCuCdZn。干、湿沉降对蔬菜体内六种元素的贡献系数从大到小排序依次为:HgAsCdPbCuZn。(4)蔬菜重金属污染评价结果表明,室外四种蔬菜中各重金属的单项污染指数按照从大到小的顺序排列依次为HgPbZnCdCuAs。室外四种蔬菜综合污染水平从高到低排序为:油麦菜、青菜、空心菜和白菜。大气沉降对于蔬菜体内重金属有显著的污染效应。干、湿沉降实验中四种蔬菜中重金属的单项污染指数按照从大到小的顺序排列依次为HgPbCdZnAsCu。四种蔬菜总体上综合污染指数从高到低排序为:油麦菜、青菜、空心菜和白菜。(5)蔬菜摄入健康风险评价结果表明,室外四种蔬菜的综合健康风险指数值TTHQ值从大到小依次为:青菜、空心菜、油麦菜和白菜。干、湿沉降后四种蔬菜中不同重金属单因子健康风险指数值THQ排序为:AsHgCdPbZnCu。从不同的受众群体来看,食用蔬菜对成人和儿童均产生一定威胁,儿童摄入蔬菜重金属健康风险普遍大于成人。总的来看,干、湿沉降后四种蔬菜的TTHQ值从大到小依次为:油麦菜、青菜、空心菜和白菜。(6)研究区大气颗粒物PM2.5中重金属单纯通过呼吸进入人体,对人体产生的健康危险较小,而通过蔬菜累积大气干、湿沉降中的重金属后,由于Hg和As产生的健康威胁较大,导致蔬菜的摄入健康风险评价较高,均对人体健康产生一定威胁。
[Abstract]:Vegetables contain a variety of essential vitamins, carbohydrates, dietary fiber and minerals, which occupy an important proportion in people's diet. In recent years, heavy metals in food have occurred frequently. The food safety problems caused by heavy metal content have attracted wide social attention. In February 2017, the State Council The national food safety plan of "13th Five-Year" was issued, emphasizing the strengthening of heavy metal pollution control and the strict implementation of the whole chain supervision from farmland to table. Heavy metals, as a kind of inorganic pollutants, have the characteristics of high rich collection and low migration, which seriously threaten the safety of natural ecological environment and human health. The growth ring of vegetables is a serious threat to the growth of vegetables. Heavy metal pollution in soil, water and atmosphere will prevent the normal growth and development of vegetables, and heavy metals in the environment will accumulate in the vegetable body. The food chain enters the human body and threatens the health of the human body. The vegetable production base in the suburb of Shanghai and the scattered farmland supply a large number of vegetables for the people of Shanghai, because of atmospheric sedimentation and sewage irrigation, These vegetables are faced with serious heavy metal pollution risk and potential safety hazard. This study selected six heavy metal elements as Cu, Zn, Pb, Cd, Hg and As as the main research indicators, combining the atmospheric particulates sampling and vegetable soil free cultivation simulation experiments in Shanghai. The effects of atmospheric sedimentation on heavy metals in vegetables were analyzed. The contribution rate of heavy metals to vegetable roots and edible parts was systematically studied through indoor dry and wet sedimentation simulation experiments. The migration and transformation of heavy metals in vegetables were revealed after the heavy metal was absorbed by vegetable leaves. The level of atmospheric particles in the region was analyzed. The level of heavy metal pollution in the atmospheric particulate matter PM2.5, the pollution level of vegetable roots and edible parts added to different concentrations of heavy metals in the leaves, in order to explore the comprehensive effects of atmospheric sedimentation and heavy metal pollution on human health in the study area. In natural condition, the mechanism of vegetable leaf surface absorption of heavy metals in atmospheric sedimentation is studied. The following conclusions are drawn as follows: (1) the average mass concentration of heavy metals in Cd, Cu, Pb, Zn, Hg and As in Minhang District PM2.5 is 0.49,5.78,17.89188,0.0104 and 2.62 ng m~ (-3) respectively. The order of different heavy metals from large to small is the ZnPbCuAsCdHg. healthy wind in turn. The risk model calculated the annual excess risk of heavy metals entering the human body in Minhang District atmospheric PM2.5 from high to low in turn from high to low to AsCdPbZnCuHg. to the adult male, 1.15 and 1.5 times as much as adult female and children. (2) atmospheric exposure and indoor simulated vegetable experiments showed that four indoor species were in room. The contents of all the elements in the edible part of the vegetables were within the standard limit. The contents of four kinds of vegetables Zn, Cd, Cu and As were less than the national standard of heavy metal pollution. The indoor simulated vegetable growth environment was better, the content of heavy metals was low, while the heavy metal content of vegetables was exceeded under the outdoor atmosphere exposure, among which Pb and the contents of heavy metals were above the standard. The content of heavy metals in the edible part of vegetables cultivated in the outdoor atmosphere exposed to Hg was generally higher than that in the indoor simulation. It showed that heavy metals in the atmospheric sedimentation had significant influence on vegetables. The contents of six kinds of heavy metals in the root of hydroponic vegetables were all low, which belonged to the safe range. The Cu, Zn, Pb and As of the edible parts of vegetables were in the area. The heavy metals in the roots showed a significant correlation. (3) under dry and wet conditions, the concentration coefficient of heavy metals in the roots of four vegetable leaves was the same from large to small, and the effect of dry settlement on the Cu, Cd and As in most of the edible parts and roots of most vegetables was greater; and Zn, Pb and Hg. On the contrary, on the whole, the ratio of heavy metal concentration to the concentration of the blank group was AsHgPbCuCdZn. dry under wet sedimentation and the ratio of the concentration of heavy metals to the blank group was AsHgPbCuCdZn.. The order of the contribution coefficient of wet sedimentation to six elements in vegetables from large to small was in turn: HgAsCdPbCuZn. (4) evaluation of heavy metal pollution in vegetables The single pollution index of heavy metals in four kinds of outdoor vegetables was arranged in sequence from large to small. The overall pollution level of four kinds of vegetables was ordered from high to low in order of HgPbZnCdCuAs. outdoor vegetables, vegetables, cabbage, cabbage and cabbage. There were significant pollution effects on heavy metals in vegetables. In dry and wet sedimentation experiments, four kinds of vegetables were found. The single pollution index of heavy metals in the vegetables was arranged in sequence from large to small. The overall pollution index of four kinds of vegetables was ordered in order of HgPbCdZnAsCu. from high to low. (5) the health risk assessment of vegetable intake showed that the value of comprehensive health risk index value of four vegetables in outdoor was from large to TTHQ value. The following are: green vegetables, cabbage, oil and wheat and cabbage. Dry and wet settlement of four kinds of vegetables in four kinds of heavy metals single factor health risk index number of order: AsHgCdPbZnCu. from the different audience group, edible vegetables have a certain threat to both adults and children, and the health risk of heavy metal intake of vegetables is generally greater than that of adults. After wet settlement, the TTHQ value of four kinds of vegetables from large to small is in turn: oil and wheat, green vegetables, cabbage and cabbage. (6) the heavy metals in the atmospheric particulate matter of the study area are simply breathing into the human body by breathing, and the health risks of the human body are small, and the heavy metals in the atmosphere through the vegetables and the heavy metals in wet sedimentation are produced by Hg and As. The risk of vegetable intake is high, which is a threat to human health.
【学位授予单位】：华东师范大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：X51;X820.4

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