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.