| 中国北方典型设施菜地土壤稀土元素分布特征及环境意义 |
| 摘要点击 2655 全文点击 1117 投稿时间：2021-08-04 修订日期：2021-09-08 |
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| 中文关键词 设施蔬菜种植 土壤 稀土元素(REEs) 环境意义 中国北方地区 |
| 英文关键词 protected vegetable planting soil rare earth elements(REEs) environmental significance Northern China |
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| 中文摘要 |
| 以我国北方地区天津武清、山西晋中、辽宁沈阳和内蒙古乌兰察布等地的典型设施菜地土壤为研究对象，分析设施蔬菜种植过程中土壤稀土元素的变化特征，尝试利用稀土元素特征值示踪、表征人类活动对土壤生态环境干扰的可行性.结果发现，辽宁沈阳设施菜地表层土壤中稀土元素总量（REE）范围为146.52~158.76mg·kg-1，均值为152.34 mg·kg-1；天津武清区设施菜地表层土壤中稀土元素总量范围为92.16~137.69 mg·kg-1，均值为115.03mg·kg-1；内蒙古乌兰察布表层土壤的总量范围为91.38~118.84 mg·kg-1，均值为108.03mg·kg-1；山西晋中榆次表层土壤的总量范围为97.62~111.27 mg·kg-1，均值为102.43mg·kg-1.以球粒陨石为参照对设施菜地土壤进行标准化所获得的4个地区土壤中稀土元素的配分模式基本一致，均表现为向右倾斜特征.土壤中轻稀土与重稀土含量的比值LREE/HREE均大于6，（La/Yb）N值大于7，表明轻稀土元素和重稀土元素之间存在明显的分异，轻稀土元素在土壤中明显富集.稀土（La/Sm）N值高于3，显示轻稀土元素之间具有明显的分馏.稀土（Gd/Yb）N值介于1~2之间，表明重稀土元素之间存在较弱的分馏现象.土壤稀土的δEu值在0.56~0.61之间，显示Eu具有明显的负异常；δCe值在0.89~1.11之间，表明Ce无异常或具有弱的正异常.四地设施菜地土壤中稀土元素的LREE/HREE、（La/Yb）N和δCe等值高于露天菜地土壤，表明设施蔬菜种植造成土壤中轻、重稀土元素的分异程度增加，Ce相对富集.随着耕作年限的加长，设施土壤的REE、LREE值有所下降，HREE值变化不明显，（La/Sm）N、δEu有所降低，（Gd/Yb）N和δCe有所增加.设施菜地土壤稀土元素的δCe、δEu、（La/Yb）N和（Gd/Yb）N等参数值与土壤容重、土壤含水率以及土壤有机质等之间有显著的相关关系，初步表明稀土元素可作为示踪元素去表征人类活动对土壤的干扰强度. |
| 英文摘要 |
| The concentrations of rare earth elements (REEs) in protected vegetable soils in Wuqing district of Tianjin City, Jinzhong district of Shanxi Province, Shenyang district of Liaoning Province, and Wulanchabu district of Inner Mongolia Autonomous Region in northern China were measured to analyze the change characteristics of soil REEs in the process of protected vegetable cultivation. Additionally, we sought to use the REEs parameters to trace the feasibility of characterizing the interference of human activities on the soil ecological environment. The results showed that the total content of REEs (REE) in the topsoil of protected vegetable fields ranged from 146.52 to 158.76 mg·kg-1, with an average of 152.34 mg·kg-1 in Shenyang; 92.16 to 137.69 mg·kg-1, with an average of 115.03 mg·kg-1in Wuqing; 91.38 to 118.84 mg·kg-1, with an average of 108.03 mg·kg-1 in Wulanchabu; and 97.62 to 111.27 mg·kg-1, with an average of 102.43 mg·kg-1in Jinzhong. The REEs distribution patterns in the soils of the four areas, standardized with chondrite, characterized by a right tilt, showed that light rare earth elements were obviously enriched in the soil, demonstrated by the ratios of LREE/HREE and (La/Yb) N, which were greater than 6 and 7, respectively. The values of (La/Sm)N in the soils were higher than 3, suggesting that there was an obvious fractionation between light rare earth elements, whereas the values of (Gd/Yb)N were between 1-2, and there was a weak fractionation between heavy rare earth elements. The values of δEu in the soils were between 0.56 and 0.61, showing that Eu had a negative abnormality. The values of δCe were between 0.89 and 1.11, showing that Ce had no abnormality or weak positive abnormality. The higher LREE/HREE and (La/Yb)N in protected vegetable soil than that in open-air vegetable soil indicated the increasing differentiation degree between light and heavy rare earth elements in protected vegetable soil. The lower (La/Sm)N in protected vegetable soils indicated the reduction in the differentiation among light rare earth elements in soil. Higher δCe values and lower δEu values suggested that Ce and Eu were relatively enriched and depleted, respectively, during vegetable planting. The REE, LREE, (La/Sm)N, and δEu in protective soil decreased with the number of cultivation years, whereas the (Gd/Yb)N and δCe increased, but the HREE values did not change significantly. There was a significant correlation between δCe, δEu, (La/Yb)N, (Gd/Yb)N, and soil bulk density, soil moisture content, and soil organic matter in Tianjin protected vegetable soils, showing preliminarily that rare earth elements can be used as tracer elements to characterize the interference intensity of human activities on soil. |
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