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稀土元素 (REEs) 由于其特殊的物理和化学性质,过去的几十年中在地球化学、农业、冶金、电子、激光、核工业和超导体领域中的广泛使用[1-4]. 近年来REEs在越来越多的环境基质中被检测到[5-6]. 据报道,土壤中的REEs含量为 30.8—327.5 ng·kg−1,地表水中的REEs含量为0.17—160.06 μg·L−1 [7-12]. 沉积物和生物体中的REEs分别为 0.0002—9850 mg·kg−1 和 1.95—7.05 mg·kg−1 dw(干重)[13]. 有研究表明,环境基质中的REEs可以通过食物链进入人体[14-15],产生潜在的健康风险. 中国拥有全球最丰富的 REEs 资源,占全球97%的 REEs 供应量[16-17],这可能会导致中国与其他国家相比具有更高的 REEs 污染水平和潜在风险. 因此,研究中国稀土元素膳食暴露特征具有重要意义和代表性.
REEs的广泛使用不仅会污染环境,而且会在生物体积累. 已有毒理学研究表明REEs主要的靶器官包括脑、肝、肾、甲状腺和甲状旁腺[8]. 据报道,脑中高浓度的 Gd会引起神经毒性[18],其他REEs还会降低大脑的智力水平,最终导致记忆力减退[19]. 此外,REEs 还可以在人体骨骼中积累并最终导致基因毒性[20]. REEs还可以穿过胎盘和血脑屏障,进而在胎儿体内蓄积,从而导致出生缺陷[21]. 已有研究表明在有神经管缺陷的新生儿中发现的 Ce 和 La 的累积水平更高[22]. 在中国矿区,居民血液中REEs含量和当地土壤中 REEs浓度显著相关[23],表明在受污染的土壤中生长的植物能够积累REEs,REEs进一步通过食物网进入人体.
目前,国内对稀土元素的研究大多集中在矿区土壤、饮用水和农作物中[24-26]. 据报道,中国最大的重稀土生产区江西赣州,其尾矿土壤的稀土元素水平高达 3179 mg·kg−1 [27],溪水高达 4.46 mg·L−1,农田土壤高达 928 mg·kg−1 [28]. 在中国最大的轻稀土产区包头市,其水体和底泥中的稀土总浓度分别为3.8 mg·L−1和30461 mg·kg−1,远高于华北地区河流的平均值[21]. 此外,矿区蔬菜中的REEs含量为 1.24–2.03 mg·kg−1 [29-31]. 但是与居民健康直接相关的市售食品中稀土元素含量的研究较少. 对中国个别城市食品中稀土元素的调查表明,非矿区蔬菜中的REEs含量为 0.37—1162 μg·kg−1 [32-33].
本研究采集大型农贸市场、超市中具有代表性和适时性的常见蔬菜食品,调查了中国沿海地区日常食用蔬菜中REEs的残留水平和分布特征. 研究成果将有助于了解中国沿海地区居民通过蔬菜摄入REEs的含量,评估人类和生态系统面临的健康风险. 将获得的数据与全国各地其他研究的结果进行比较,也将有助于研究所调查环境中REEs随时间和地点的变化趋势.
我国东部沿海地区蔬菜中稀土元素的累积分布特征及健康风险评价
Accumulation characteristics and health risk assessment of rare earth elements in vegetables from the eastern coastal region of China
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摘要: 为调查我国东部沿海地区蔬菜样品中稀土元素的累积水平和分布特征. 采集了市售叶类、根茎类、瓜果类、豆类及食用菌5类蔬菜样品,采用电感耦合等离子体质谱(ICP-MS)对15种稀土元素(La、Ce、Pr、Nd、Sm、Eu、Gd、Tb、Dy、Ho、Er、Tm、Yb、Lu和Y)进行了分析. 不同蔬菜样品中ΣREE浓度范围为 2.72—55.16 μg·kg−1 fw(鲜重),平均浓度为 16.63 μg·kg−1 fw. 其中,叶类蔬菜的ΣREE含量最高(平均值为38.43 μg·kg−1 fw),而根茎类蔬菜中ΣREE含量最低(8.82 μg·kg−1 fw). 居民通过消费蔬菜样品带来的稀土元素总摄入量为0.41 μg·(kg·d)−1,远低于稀土元素摄入的安全剂量(70 μg·(kg·d)−1),表明正常饮食情况下居民通过蔬菜摄入的稀土量是安全的,但居民的稀土暴露途径还包含其它各种食品摄入,呼吸以及饮水暴露,还受到多种环境因素的影响,我国沿海地区居民的稀土摄入是否安全还需要综合评价.Abstract: Five representative vegetable categories, namely, leafy, root, melons, legumes, and edible fungi vegetables were collected to investigate the residual levels and accumulation characteristics of rare earth elements (REEs) in vegetable samples from the east coast of China, 15 REEs in vegetables were characterized by inductively coupled plasma mass spectrometry (ICP-MS), including La、Ce、Pr、Nd、Sm、Eu、Gd、Tb、Dy、Ho、Er、Tm、Yb、Lu, and Y. The concentrations of REEs in vegetables ranged from 2.72 μg·kg−1 to 55.16 μg·kg−1 fresh weight (fw), with an average of 16.63 μg·kg−1 fw. Leafy vegetables exhibited the highest ΣREE concentration (average 38.43 μg·kg−1 fw), while root vegetables posed the lowest ΣREE concentration (average 8.82 μg·kg−1 fw). The estimated daily intake (EDI) was calculated to evaluate the potential dietary intake risks of REEs. The average EDI of REEs in vegetables was 0.41 μg·kg−1·d−1, which was far lower than the safe dose threshold (70 μg·kg−1·d−1), indicating an acceptable healthy risk of REEs by daily vegetables consumption in the east coast region of China. However, the REEs exposure of residents also include the intake of various other foods, as well as the inhalation and water-drinking exposure, affected by multiple other environment factors. Whether the intake of REEs by residents in coastal areas is safe needs a further comprehensively evaluation.
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Key words:
- rare earth elements /
- coastal areas /
- vegetables /
- accumulation characteristics /
- dietary exposure.
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表 1 不同类别蔬菜品种及样本量
Table 1. Sample species and sizes of different types of vegetables
样品类别
Sample蔬菜品种及采样量
Vegetables categories and sample volume采集地点
Sampling location叶类蔬菜
Leafy vegetables菠菜Spinacia oleracea L.(3)、上海青Brassica chinensis L.(8)、卷心菜Brassica oleracea L.(4)、生菜Lactuca sativa var. ramosa Hort.(3)、娃娃菜Brassica campestris L.(3)、白菜Brassica pekinensis (Lour. ) Rupr.(1)、红苋菜Amaranthus mangostanus L.(2)、油麦菜Lactuca sativa var. longifoliaf. Lam(2)、芥菜Brassica juncea(1)和菜心Brassica campestris L. ssp. chinensis var.utilis Tsen et Lee(1) 大连、营口、青岛、苏州、上海、舟山、福州、广州 根茎类蔬菜
Root stem vegetables胡萝卜Daucus carota var. sativa Hoffm.(3)、洋葱Allium cepa L.(5)、白萝卜Raphanus sativus(4)、蒜薹Allium sativum L.(2)、山药Dioscoreae Rhizoma(1)、大蒜Allium sativum L.(1)、大葱Allium. fistulosum L.var.gigantum Makino(1)、藕Nelumbo nucifera Gaertn(1)、芹菜Apium graveolens L.(1)和毛茭白Zizania latifolia (Griseb. ) Stapf(1) 大连、营口、天津、青岛、苏州、上海、舟山 瓜果类蔬菜
Melon vegetables西红柿Lycopersicon esculentum(6)、茄子Solanum melongena L.(7)、黄瓜Cucumis sativus L.(6)、丝瓜Luffa aegyptiaca Miller(2)、甜椒Capsicum frutescens L. (syn. C. annuum L. )var. grossum Bailey.(4)、冬瓜Benincasa hispida (Thunb. ) Cogn.(1)、尖椒Capsicum frutescens L.(1)、西葫芦Cucurbita pepo L.(2)、苦瓜Momordica charantia L.(1)、秋葵Abelmoschus esculentus (L. ) Moench(1)和西蓝花Brassica oleracea var. italica Plenck(1) 大连、天津、青岛、苏州、上海、舟山、福州、广州 豆类蔬菜
Legume vegetables芸豆Phaseolus vulgaris(5)、扁豆Lablab purpureus (Linn. ) Sweet(1)、荷兰豆Pisum sativum L.(2)、豇豆Vigna unguiculata (Linn.) Walp.(2)、甜豌豆Lathyrus odoratus(1)、油豆角Phaseolus vulgaris Linn.(1) 营口、秦皇岛、天津、青岛、上海、舟山、泉州 食用菌
Fungi vegetables香菇Lentinula edodes(5)、花菇Lentinus edodes (Berk.)Sing(1)、杏鲍菇Pleurotus eryngii Quel.(3)、鸡腿菇Copyinds comatus (MUII. Fr)Gray(1)、口蘑Tricholoma gambosum(1)、金针菇F. velutipes(1)和白玉菇Hypsizygus marmoreus (Peck) H.E.Bigelow(1) 营口、秦皇岛、青岛、苏州、上海、舟山、泉州 表 2 我国沿海地区蔬菜样品中轻稀土元素和重稀土元素含量
Table 2. Contents of LREEs and HREEs in vegetable samples from coastal areas of China
样品名称
SamplesΣREE/(μg·kg−1 fw) LREEs HREEs LREE/HREE 北方沿海 叶类蔬菜 55.16 45.84 9.32 4.92 根茎类蔬菜 6.50 5.87 0.63 9.35 瓜果类蔬菜 2.72 2.36 0.36 6.53 豆类蔬菜 4.41 3.79 0.63 6.03 食用菌 13.84 12.10 1.74 6.97 南方沿海 叶类蔬菜 21.69 18.15 3.54 5.12 根茎类蔬菜 11.14 10.60 0.54 19.71 瓜果类蔬菜 28.28 26.28 2.00 13.13 豆类蔬菜 16.67 14.25 2.42 5.89 食用菌 5.88 5.11 0.76 6.69 表 3 我国东部沿海地区蔬菜中稀土元素水平以及日摄入值估算(EDI)
Table 3. EDI contribution in vegetable samples from coastal areas of China
元素
Elements浓度范围/(μg·kg−1 fw)
Concentration range平均浓度/(μg·kg−1 fw)
Average concentrationEDI(以体重计)/(μg·(kg·d)−1) 北方沿海 南方沿海 Y
La
Ce
Pr
Nd
Sm
Eu
Gd
Tb
Dy
Ho
Er
Yb0.23—5.44
0.28—10.55
1.35—21.86
0.07—2.34
0.25—8.82
0.35—1.92
0.02—0.37
0.07—1.42
0.00—0.20
0.02—1.10
0.00—0.19
0.02—0.54
0.01—0.421.30±1.6
3.83±3.6
7.10±6.4
0.60±0.7
2.14±2.6
0.67±0.5
0.09±0.1
0.35±0.4
0.05±0.1
0.24±0.3
0.04±0.1
0.12±0.2
0.09±0.10.037
0.075
0.178
0.017
0.062
0.020
0.003
0.010
0.001
0.008
0.001
0.004
0.0030.027
0.109
0.167
0.012
0.043
0.013
0.002
0.007
0.001
0.004
0.001
0.002
0.002∑REE 2.72—55.16 16.63±15.8 0.42 0.39 -
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