Magnetic proxy methods are effective tools for detecting anthropogenic heavy metal pollution of the environment. In this study we investigated the viability of using this method in an area of a complex setting where natural geogenic input, interfering land-use, and multiple different industries affect the magnetic signal. For this purpose, we took surface (N = 70) and core (N = 18) samples from an ~80 km² area in the south-eastern Nile delta that was partly flooded before construction of a major dam, with overlapping agricultural, residential (urbanization and land reclamation), and multiple industrial activities. Using ICP-MS we characterized the spatial pollution pattern and found enrichments in seven potentially toxic heavy metals; Cu, Zn, Pb, As, Sb, Cd, and Hg, located near industrial hotspots, with highly varying pollution levels, high concentrations in the upper soil and clear depletion with depth. Magnetic susceptibility (ϰ) was measured in-situ at 170 sites, and on all samples. Thermomagnetic runs reveal that magnetite and Ti-rich titanomagnetite control the magnetic signal. Despite industrial activities are predominantly located in more sandy areas, and ϰ is found to be strongly related to spatial lithological variation, the magnetic results reasonably outline the industrial areas and show elevated ϰ levels around drains where pollutants are discharged and redistributed by irrigation. In most of these locations, ϰ decreases with depth in parallel with the pollution level, and there is a moderate correlation of ϰ with the pollution load index for the topsoil values of the core samples normalized to their bottom values. Despite the area's complexity, the spatial ϰ pattern matches reasonably well with the chemistry data of cores located in the vicinity of the main industrial spots. Therefore, also for this complex setting, time-efficient ϰ mapping provides a helpful tool as a qualitative approach for detecting key features of the spatial distribution of pollutants, which will be useful for supporting a better-targeted chemical sampling.

磁替代方法是检测人为环境中重金属污染的有效工具。在这项研究中，我们调查了在自然地理输入，干扰土地利用以及多种不同行业影响磁信号的复杂环境中使用这种方法的可行性。为此，我们从〜80 km ²采集了表面（N = 70）和岩心（N = 18）样本尼罗河东南部地区，在建造大坝之前被部分洪水淹没，农业，住宅（城市化和土地开垦）和多种工业活动重叠。使用ICP-MS，我们表征了空间污染模式并发现了七种潜在有毒重金属的富集；Cu，Zn，Pb，As，Sb，Cd和Hg位于工业热点附近，污染水平变化很大，上部土壤中的浓度很高，并且深度上明显耗竭。在170个位置和所有样品上原位测量磁化率（ϰ）。热磁运行表明，磁铁矿和富钛的钛磁铁矿控制着磁信号。尽管工业活动主要位于更多的沙质地区，并且发现ϰ与空间岩性变化密切相关，磁化结果合理地勾勒出了工业区的轮廓，并显示了排水沟附近ϰ水平的升高，在这些排水沟中，污染物通过灌溉被排放和重新分配。在大多数这些位置，ϰ随深度的增加与污染水平平行而减小，并且ϰ与归一化为其底部值的岩心样品的表层土壤值的污染负荷指数之间存在适度的相关性。尽管该地区非常复杂，但其空间ϰ模式与位于主要工业区附近的岩心的化学数据相当吻合。因此，对于这种复杂的设置，高效的ϰ映射提供了一种有用的工具，可以作为一种定性的方法来检测污染物空间分布的关键特征，这将有助于支持针对性更强的化学采样。