青岛石老人海滩表层沉积物原位磁化率时空变化及其对重金属污染的指示

    Spatiotemporal variation of in-situ magnetic susceptibility of surface sediments at Qingdao Shilaoren Beach and its indication to heavy metal pollution

    • 摘要: 海滩沉积物常常含有一定的磁性矿物。本研究于2022年7月和12月夏冬两个季度对青岛市石老人海滩的体积磁化率进行原位测量,分析石老人海滩表层沉积物的体积磁化率时空变化,建立磁化率与重金属含量的关系。结果表明,石老人海滩不同季节表层沉积物体积磁化率值和重金属含量总体上均呈现冬季高、夏季低的特点。主要是由于冬季风力较强,密度较轻的颗粒被吹走,留下密度大的磁性颗粒,增大了海滩沉积物的磁性,同时冬季排污的增多也导致了重金属含量和海滩整体磁化率值的升高。除此之外,海滩的体积磁化率东西两侧高,冬季海滩东侧排污口附近的体积磁化率最高可达9 000×10−5 SI,主要是受海滩东西两侧排污口及建筑活动的影响;而波浪作用形成了后滨高、前滨低的趋势。体积磁化率数据与重金属含量具有很好的相关性(R2=0.71~0.83),在空间分布上具有一致性,表明海滩表层沉积物体积磁化率不仅能反应海滩污染状况,而且对重金属污染和扩散路径有一定的指示意义。

       

      Abstract: Beach sediments often contain certain magnetic minerals. An in-situ measurement of volume magnetic susceptibility was conducted in 2022 summer (July) and winter (December) in Shilaoren Beach, Qingdao, Shandong, East China. The spatial and temporal changes in the volume magnetic susceptibility of the surface sediments were analyzed, and the relationship between magnetic susceptibility and heavy metal content was established. Results show that the magnetic susceptibility values and heavy metal content of the surface sediments were generally higher in winter and lower in summer due mainly to stronger wind in winter, blowing away the lighter particles, leaving heavier magnetic particles, which increased the magnetism of the beach sediments. Additionally, the increase in sewage discharge during winter contributed to the elevated heavy metal content and overall magnetic susceptibility. Moreover, we found that the magnetic susceptibility of the beach sediments was higher in the eastern and western ends. In winter, the volume magnetic susceptibility near the sewage outlet on the eastern end of the beach reached 9 000×10−5 SI units. This increase can be primarily attributed to the influence of sewage outlets and construction activities there. Wave action also created a pattern where the backshore exhibited higher magnetic susceptibility compared to the foreshore. Furthermore, the volume magnetic susceptibility data shows a strong correlation (R2=0.71−0.83) with heavy metal content, and both exhibited consistent spatial distribution patterns. Therefore, the volume magnetic susceptibility of beach surface sediments can not only reflect the pollution status of the beach but also provide significant insights into the pathways and diffusion of heavy metal pollution. Overall, the findings suggest that magnetic susceptibility measurement is a valuable tool for assessing and monitoring beach pollution, particularly in relation to heavy metal contamination.

       

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