【作者】 方华为；

【导师】 唐世荣； 涂书新；

【作者基本信息】 华中农业大学 ， 土壤学， 2011， 硕士

【摘要】 环境问题已经成为当今世界最受公众关注的问题之一,而土壤重金属污染是全球面临的重大环境问题之一。土壤重金属因其特有的生物毒性和易积累性,对生态系统和人类健康构成了严重的威胁,其中镉更易被作物吸收并通过食物链富集,进而威胁食品安全并影响人类健康。目前应对土壤重金属污染的策略主要包括物理、化学和生物的方法,其中植物修复的方法具有更多的优点,但这种方法对功能植物筛选的依赖性很强。植物吸收和累积重金属存在显著的植物种间和种内差异,从而为功能物种的筛选提供了可能。本研究采用盆栽实验的方法,利用方差分析和聚类分析比较了71种叶菜类蔬菜对土壤镉的吸收积累差异性,利用靶标危害系数法评价了镉通过食物链积累对人类健康产生的生态风险,以及利用镉污染土壤上蔬菜根系形态特征进行产地环境安全性评价,得出主要结论如下：1.镉污染土壤(1.6mg kg-1)上空心菜(Ipomoea aquatica Forsk.)、油麦菜(Lactuca sativa L.)和生菜(Lactuca sativa L.var.capitata L.)在营养生长期其地上部隔含量变化规律是升高(8叶期)——平衡(12叶期)——升高(16叶期)——平衡(20叶期),最高浓度出现在营养生长期后期(本试验中为16叶期)。2.同一科属不同品种以及同一品种不同基因型蔬菜地上部生物量对镉的反应均不同,按差异情况可以将其分成高敏感、敏感、高耐受、耐受和其他等5类。3.同一科属不同品种以及同一品种不同基因型蔬菜对Cd的吸收能力也有较大差异,71种叶菜类蔬菜按地上部(烘干样)Cd含量根据聚类结果可分为低、中、高、较高、最高等五个级别,在土壤Cd为2.12mg kg-1时各级别蔬菜地上部Cd含量范围：低0.45-1.16mg kg-1、中1.27-2.29mg kg-1、高2.36-2.66mg kg-1、较高1.49-4.11mg kg-1和最高4.69-5.04mg kg-1。71种蔬菜地上部对Cd的生物富集系数可分为低、中、高三大类,结果还表明不同浓度Cd对同一种蔬菜的转运系数能产生显著影响,在土壤Cd为0.31、1.20和2.12mg kg-1时蔬菜转运系数的变化有依次递减、依次递增、先增后减、先减后增和无影响等5种类型,具体情况又因不同蔬菜品种而异。4.本实验中叶菜类蔬菜对低Cd污染土壤的植物修复潜力不大,71种叶菜类蔬菜茎叶中最高Cd含量仅为5.04 mg kg-1,最高Cd累积量仅为7.81μg pot-1,土壤中Cd的最高净化率为0.74%(土壤Cd为2.12mg kg-1时)。5.在土壤Cd含量为2.12mg kg-1时,叶菜类蔬菜地上部镉平均含量依次为油麦菜>生菜>菜薹(Brassica campestris L. ssp.chinensis var.utilis Tsen et Lee)>莴苣(Lactvca saiva L.lettuce)>空心菜>芹菜(Apium graveolens L.celery)>小白菜(Brassica campestris L. var. communis Tsen et Lee)>大白菜(Brassica campestris L. ssp. Pekinensis (Lour.) Olsson)>芥菜(Brassica juncea)>香菜(Herba Coriandri Sativi)>苦苣(Cichorium endiviaL.common)>香葱(Allium porrum L.leek)>甘蓝(Brassicaoleracea var.capitata f.rubra)>木耳菜(Gynura cusimbua (D. Don) S. Moore)>茼蒿(Chrysanthemum soronarium L.garland chrysanthemum)>苋菜(Amaranthus mangostanus L.edible amaranth)>韭菜(A. tuberosum Rott, ex Spr. Chinese chive)。蔬菜对土壤Cd吸收能力按科属分类结果表明,莴苣属蔬菜对Cd的吸收能力最强,甘薯属、云姜属、芹属、菊苣属为中等吸收能力,而茼蒿属、葱属、落葵薯、苋属对Cd吸收能力最低。6.不同蔬菜对人体产生的健康风险因品种而异,试验中叶菜类蔬菜对城区居民的风险性高于郊区居民。土壤Cd含量≤2.12mg kg-1时,油麦菜、生菜、莴苣、芹菜、香菜和空心菜表现出高的风险性,甘蓝、茼蒿、韭菜、木耳菜和苋菜表现最为安全。7.镉对不同蔬菜总根长、根总表面积、根总体积、根平均直径和根尖数等形态指标能产生显著影响,有刺激作用也有抑制作用,影响程度因品种和土壤Cd含量不同而异,利用产地环境安全性辅助决策系统对产地环境安全性进行评估具有一定的可行性,但仍需在原始数据积累和限制条件等方面进一步完善。上述研究结果对中轻度污染土壤初级农产品安全生产、产地环境重金属污染评价、植物修复等都具有一定的指导意义。更多还原

【Abstract】 Environmental issue has become one of the greatest concerns in this world today. Moreover, heavy metal contamination in soil is one of the most serious global environment problems. As their unique biological toxicity and easy accumulation, heavy metals pose a serious threat to ecosystem and human health, cadmium is more easily to be absorbed by crops and enriched by food chain, and then threaten food security and affect human health. There are two strategies to solve heavy metal pollution problems. One is remediation and the other is selection and breeding of heavy metal pollution-safe cultivars. As plants uptake and accumulate heavy metals present significant differences among and within species, it provides the possibility of species selection. In this study a pot experiment was used to study the influence of three degrees of Cd to 71 usual vegetables’growth, and differences of absorption and accumulation of cadmium and vegetable root morphology characters. Statistical analysis was carried out by Anova and Cluster analysis. Meanwhile, Target Hazard Quotient (THQ) was used to evaluate the health risks of Cd in these vegetables, and Environmental Security Decision Assistant System was build to evaluate field Environmental security. The pot experiment results show that:1. Cd concentration in the shoots of Ipomoea aquatica(Ipomoea aquatica Forsk.)、Leaf-used lettuce(Lactuca sativa L.) and Romaine (Lactuca sativa L.var.capitata L.) changes during their vegetative growth generally followed the order:increased (8 leaves stage)——stabilized (12 leaves stage)——increased (16 leaves stage)——stabilized (20 leaves stage),the highest concentration appears in the late vegetative stage (16 leaves stage in this study), no obvious injured symptom was observed.2. Effects of Cd on the vegetable biomass showed significant differences within and among species,differences in the situation can be classified into highly sensitive, sensitive, high tolerant, tolerant, and the other.3. It could be concluded that different vegetables had different accumulation abilities for Cd. According to the concentration of Cd in the shoots, these 71 leafy vegetables can be classified into low, medium, high, higher and highest clusters.Under 2.12 mg kg-1Cd exposure,concentrations of Cd in Low-level was in a range of 0.45-1.16 mg kg-1, medium-leve 11.27～2.29 mg kg-1, high-level 2.36-2.66 mg kg-1, higher-level 1.49～4.11 mg kg-1 and highest-level 4.69-5.04 mg kg-1. The bioconcentration factors of these 71 vegetables can be divided into low, medium and high categories.we also find that Cd can significantly affect the transfer coefficient of the same vegetable. When exposure to 0.31,1.20 and 2.12 mg kg-1 of Cd, the transfer coefficient of various vegetables has decreased in turn, ascended in turn, first increased and then decreased, first decreased and then increased, and no effect totally 5 types, Circumstances vary for different varieties of vegetables.4. In this study, it was concluded that leafy vegetables have little potential on the phytoremediation of cadmium contaminated soil,the highest concentration of Cd in shoots of vegetables is 5.04 mg kg-1, the highest intake of Cd by vegetable cultivars was 7.81μgpot-1, the highest purification ratio of cadmium in soil was 0.74% (soil Cd:2.12 mg kg-1).5. Under 2.12 mg kg-1 Cd exposure, Cd concentration in shoots of these vegetables were weakening followed the order:Leaf-used lettuce>Romaine> Flowering chinese cabbage(Brassica campestris L. ssp.chinensis var.utilis Tsen et Lee)> Lettuce (Lactvca saiva L. lettuce)> Ipomoea aquatica> Celery(Apium graveolens L. celery)> Cole (Brassica campestris L. var. communis Tsen et Lee)> Chinese cabbage(Brassica campestris L. ssp. Pekinensis(Lour.) Olsson)> Shepherd’s purse(Brassica juncea)> Coriander(Herba Coriandri Sativi)>Common sowthistle(Cichorium endiviaL. common) >Chive(Allium porrum L.leek)>Kale(Brassica oleracea var.capitata f.rubra)> Malabar spinach(Gynura cusimbua(D. Don) S. Moore)> Chrysanthemum (Chrysanthemum soronarium L.garland chrysanthemum)> Amaranth(Amaranthus mangostanus L. edible amaranth)>Leek(A.tuberosum Rott, ex Spr. Chinese chive)。6. Different vegetables have different risks due to different cultivars, urban residents have higher risks than rural residents by eating the same vegetables. Under 2.12 mg kg-1 Cd exposure, leaf-used lettuce, romaine, lettuce, celery, coriander and ipomoea aquatica showed high risks to human health, however, kale, chrysanthemum, leek, malabar spinach and amaranth were safer than others.7. Root volume, length, surface area, tip numbers were significantly effected by the presence of Cd. they were inhibited or stimulated, determined by cultivars and soil Cd concentration. It was feasible to assess field environmental by Environmental Security Decision Assistant System, But it’s further application need more raw data accumulation and improvement of restricted conditions.The results of this study can provide detailed information to the primary production of agricultural soils, assessment of environmental heavy metal pollution and phytoremediation.更多还原