Magnetic properties of the urban soils in Shanghai and their environmental implications
Magnetic properties of the urban soils in Shanghai and their environmental implications
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DOI：
10.1016/j.catena.2006.11.010
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发表时间：
2007-08
期刊：
影响因子：
6.2
通讯作者：
Xuefeng Hu;Yu-Shou Su;Rong Ye;Xiao-Qing Li;Gan Zhang
中科院分区：
文献类型：
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作者：
Xuefeng Hu;Yu-Shou Su;Rong Ye;Xiao-Qing Li;Gan Zhang
为探讨磁测技术在上海土壤污染监测中的可行性，对上海市宝山区松南镇和罗泾镇表层土壤的磁性和重金属含量进行了研究。与背景值相比，城市表层土壤的磁化率（χ lf）在127.3~1959 × 10 − 8m3kg − 1之间，磁信号显著增强，而农业表层土壤的磁信号仅略有增强。城市和农业表土的成土性SP颗粒含量均较低（χ fd %<3.6%）。χ arm/SIRM、χ arm/χ lf和SIRM/χ lf的比值表明，城市表层土壤磁性矿物的粒度明显粗于背景土壤和农业表层土壤。此外，城市表层土壤表现出低磁化率和磁性软行为，如较高的SOFT %，较低的HARD %，较高的IRM300 mT/SIRM（接近1）和较低的IRM-200 mT/SIRM（接近-1）所示。这表明，城市表层土壤已接受了一些粗亚铁磁性颗粒。重金属在表层土壤磁性组分中高度富集。城市表层土壤磁性组分的地球化学性质与农业表层土壤磁性组分的地球化学性质存在显著差异，进一步表明城市表层土壤中积累的额外磁性矿物既不是来自成土母质的遗传，也不是来自成土过程，而是来自人类活动。土壤重金属含量与表层土壤的χ lf、χ arm、SIRM、SOFT和HH_2O之间存在显著相关性，表明磁测技术可用于上海地区土壤污染监测。区内土壤的χ lf在39 - 50 × 10 − 8m3kg − 1之间的土壤暂定为"轻度污染土壤"; χ lf> 50 × 10 − 8m3kg − 1的土壤暂定为"污染土壤"。
To study the feasibility of using magnetic techniques for monitoring soil pollution in Shanghai, magnetic properties and heavy metals in the topsoils in an urban site (Songnan Town) and a less-urbanized agricultural site (Luojing Town) in Baoshan District, Shanghai, were studied. Compared with the background, magnetic signals of the urban topsoils are extremely enhanced with magnetic susceptibility (χlf) from 127.3–1959×10−8m3kg−1; while those of the agricultural topsoils are only slightly increased. However, both the urban and agricultural topsoils contain few pedogenic SP grains, as indicated by their low χfd% (<3.6%). Ratios of χarm/SIRM, χarm/χlfand SIRM/χlfindicate that the grain size of magnetic minerals in the urban topsoils is significantly coarser than that in the background and the agricultural topsoils. Furthermore, the urban topsoils show low coercivity and magnetic soft behaviors, as indicated by higher SOFT%, lower HARD%, higher IRM300 mT/SIRM (close to 1) and lower IRM−200 mT/SIRM (close to −1). It suggests that the urban topsoils have received some coarse ferrimagnetic particles. Heavy metals are highly enriched in the magnetic fractions of the topsoils. Geochemical properties of the magnetic fraction of the urban topsoils are significantly different from those of the agricultural topsoils, further indicating that the extra magnetic minerals accumulated in the urban topsoils are neither inherited from soil parent materials nor from pedogenic processes, but originate from anthropogenic activities. The significant correlations between heavy metals and χlf, χarm, SIRM, SOFT and HIRM of the topsoils in the district indicate that the magnetic techniques can be used for monitoring soil pollution in Shanghai. The soils with χlffrom 39–50×10−8m3kg−1in the district are tentatively defined as “slightly polluted soils”; those with χlf>50×10−8m3kg−1are defined as “polluted soils”.