【目的】 廉价、高效、样品无损伤的磁化率技术在城市土壤重金属污染监测与评价研究中有诸多成功应用案例。青藏高原东缘地区具有独特的高原生态系统和脆弱的环境条件,为保障该区居民的健康,研究青藏高原东缘地区城市土壤中重金属的分布、来源及其潜在的健康风险现状。【方法】以青藏高原东缘典型城市海东市表层土壤为研究对象,通过典型城市表土采样试验与文献解析相结合的研究方法,系统评价研究区表土磁性物质的空间分布与污染特征;分析海东市城区不同功能区表土磁化率分布特征及在0~6 cm深度上表土剖面的变化规律,并综合分析青藏高原东缘及周边地区土壤磁化率分布特征。【结果】①海东市表土的质量磁化率具有强变异水平(变异系数0.65),质量磁化率在垂直剖面上呈随深度增加而减小的趋势;表土中超顺磁颗粒含量较少,主要由成土作用形成。②基于磁化率浓集因子和污染负荷指数的污染评价结果表明,海东市表土处于轻度污染或无污染状态,重金属Cr、Cu、Mn、Fe、Ni主要来自成土过程,Cd、Pb、Zn主要来源于人为活动。③低频质量磁化率(χ_lf)的半定量化模型结果为χ_lf<59.7×10^-8 m³/kg时土壤为清洁状态;χ_lf为[59.7×10^-8, 498.0×10^-8) m³/kg时土壤受轻度污染;χ_lf为[498.0×10^-8, 998.0×10^-8) m³/kg时土壤受中度污染;χ_lf≥998.0×10^-8 m³/kg时土壤受重度污染。④青藏高原东部地区表土的磁化率远小于其周边重工业城市。【结论】海东市表土磁化率与重金属元素之间的相关系数存在差异,但均有显著的相关性、磁化率可以作为快速监测和评价青藏高原东缘地区土壤重金属污染的有效指标。

【Objective】 Magnetic susceptibility technology, known for its affordability, efficiency, and non-destructive nature, is widely used for monitoring and evaluating heavy metal pollution in urban soil. The eastern margin of the Qinghai-Xizang Plateau, with its unique plateau ecosystem and fragile environmental conditions, presents significant challenges. Understanding the distribution, sources and potential health risks of heavy metals in this region’s urban soil is crucial for protecting local residents’ health. 【Method】This study focused on Haidong, a representative city on the eastern margin of the Qinghai-Xizang Plateau. It systematically evaluated the spatial distribution and pollution characteristics of the surface soil through a combination of soil sampling and literature analysis. The analysis included the distribution of surface magnetic susceptibility in different functional areas of Haidong and the variation of magnetic susceptibility in soil profiles at a depth of 0-6 cm. Additionally, the study examined the distribution characteristics of soil magnetic susceptibility in the eastern margin of the Qinghai-Xizang Plateau and surrounding areas. 【Result】(1) The mass magnetic susceptibility of surface soil in Haidong showed significant variation (CV=0.65), decreasing with depth. The topsoil contains few superparamagnetic particles, mainly due to soil formation. (2) Pollution evaluation using magnetic susceptibility concentration factors and pollution load indices indicated that Haidong’s topsoil was either slightly polluted or non-polluted. Heavy metals such as Cr, Cu, Mn, Fe, and Ni originated primarily from soil formation, while Cd, Pb, and Zn were mainly from human activities. (3) The low frequency mass magnetic susceptility χ_lf semi-quantization model results were as follows: χ_lf < 59.7 × 10^-8 m³/kg indicates clean soil; [59.7 × 10^-8, 498.0 × 10^-8) m³/kg indicated slight pollution; [498.0 × 10^-8, 998.0 × 10^-8) m³/kg indicated moderate pollution; χ_lf ≥ 998.0 × 10^-8 m³/kg indicated severe pollution. (4) The magnetic susceptibility of the eastern Qinghai-Xizang Plateau was significantly lower than that of surrounding heavy industry cities. 【Conclusion】While the coefficients between surface magnetic susceptibility and heavy metal elements in Haidong varies, a significant correlation exists. Magnetic susceptibility serves as an effective index for rapid monitoring and evaluation of soil heavy metal pollution on the eastern margin of the Qinghai-Xizang Plateau.