Objective It is known that upper layer pollutants from electrical waste dismantling sites have the potential to migrate to lower layer of soil. Understanding the community and functional characteristics of soil microbiomes at varying depths could assess the potential for biodegradation.

Method At an electrical waste dismantling site located in Taizhou, Zhejiang Province, six sampling points were established. Samples were collected from soil columns at upper layer (0 ~ 1 m) and lower layer (5 ~ 6 m). The microbial composition and functional characteristics of soil microorganisms at different depths were compared using 16S rRNA gene amplicon sequencing and metagenome sequencing methods.

Result Analysis of 16S rRNA gene amplicon sequencing results revealed differences in microbial compositions between upper layer and lower layer, with significantly lower microbial diversity in the lower layer. Sulfur oxidation-dependent chemoautotrophic microorganisms, as well as bacteria adapted to oligotrophic environments, were found to be abundant in the lower layer. Furthermore, the bacterial coexistence network structure was found to be much more complex in the upper layer. Metagenome sequencing results showed that the functional characteristics of soil microorganisms differed between upper layer and lower layer, with stronger sulfur oxidation and autotrophic metabolism potential in the lower layer. Both upper layer and lower layer also exhibited the potential to degrade a variety of organic pollutants, while the abundance of specific degradation genes differed.

Conclusion This study underscores the impact of depth on soil microbial community structures at electrical waste dismantling sites, with significant differences in energy metabolism and carbon assimilation characteristics. The findings suggest that organic pollutants in soil upper layer and lower layer may follow different microbial transformation patterns. Overall, this study provides valuable insights into pollution management and ecological restoration efforts at electrical waste dismantling sites.