| 海陆交互带土壤及河流沉积物中镉含量及形态分布特征 |
| 摘要点击 1903 全文点击 798 投稿时间：2020-03-03 修订日期：2020-04-09 |
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| 中文关键词 土壤镉含量 空间分布 影响因素 Cd形态 南沙 |
| 英文关键词 soil cadmium content spatial distribution influencing factors Cd fractions Nansha |
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| 中文摘要 |
| 镉污染对人类健康构成威胁，研究土壤中镉的空间分布可以用来评估对人类和环境构成的风险.通过分析海陆交互带不同埋深土壤中的重金属镉（Cd）含量及形态，揭示了土壤重金属镉的富集特征及变化规律.结果表明：1广州南沙区地表水中Cd质量浓度均低于0.0001 mg ·L-1，河流沉积物的理化性质以上横沥水道为界呈现空间差异，重金属Cd主要沉积在上横沥以北，总Cd均值为2.71mg ·kg-1，上横沥水道及以南河流沉积物总Cd为0.062~0.39mg ·kg-1，对海洋环境危害小；②土壤剖面Cd含量随土壤埋深增加逐渐减小，埋深0~20、20~50、50~90、90~140和140~200cm等5层剖面Cd含量中值依次为0.51、0.50、0.45、0.42和0.33mg ·kg-1，且离散程度随埋深增加逐渐减小，pH小于5的土壤中Cd在垂向上的迁移量及迁移深度显著增加；③土壤中残渣态Cd约占40%，随埋深变化趋势基本持平，弱酸提取态Cd占比中值与pH的变化一致，均随剖面埋深的增加而增大；可还原态Cd占比中值与铁、锰含量的变化一致，随剖面埋深的增加而减小.这些结果对城市周边农田土壤Cd污染的区域防治、污染土壤治理修复具有重要的指导意义. |
| 英文摘要 |
| Cadmium pollution poses a threat to human health. The examination of spatial distribution of Cd in soils can be used to assess the risks posed to humans and the environment. The enrichment characteristics and variation rules of heavy metal cadmium in the soil were revealed by analyzing the concentration and fractions of Cd in the soil at different depths in the sea-land interaction zone. The results showed that: ① the concentration of Cd in the surface water of Nansha was lower than 0.0001 mg ·L-1, and the physical and chemical properties of river sediments showed spatial differences with the boundary of "Shang Heng-li River". Cd was mainly deposited in the north of the "Shang Heng-li River", with the mean total Cd of 2.71 mg ·kg-1. The total Cd in the sediment of the "Shang Heng-li River" and the rivers south of it were 0.062-0.39 mg ·kg-1, which caused minimal harm to the marine environment. ② The content of Cd in the soil profile gradually decreased with an increase in soil burial depth. The median content of Cd in the five layers, including 0-20 cm, 20-50 cm, 50-90 cm, 90-140 cm, and 140-200 cm, were 0.51, 0.50, 0.45, 0.42, and 0.33 mg ·kg-1, respectively, and the dispersion degree gradually decreased with an increase in buried depth; the vertical migration amount and migration depth of Cd increased significantly in soils with pH less than 5. ③ The residual Cd in the soil accounted for approximately 40%, and the trend was typically flat with a change in buried depth. The median proportion of acid soluble Cd was consistent with the change in pH and increased with an increase in the buried depth of the profile, while the median proportion of reducible Cd was consistent with the change in iron and manganese content, and decreased with an increase in buried depth of section. These results have important guiding significance for the regional prevention and control of Cd pollution in farmland surrounding cities and the treatment and remediation of polluted soil. |
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