Industrial emissions are a central environmental concern, particularly with respect to the spatial distribution of major enterprises and the identification of key determinants. Traditional research has largely focused on characterizing the current status of these enterprises, but this approach exhibits several notable shortcomings. These include a lack of regional statistical analysis, an absence of a comprehensive industrial typology, inadequate cross-evaluation of enterprise scale and pollution emissions, and insufficient exploration of socioeconomic correlations. We introduce a multifaceted evaluation framework for Key Environmental Supervision Units (KESUs), focusing on key industrial classifications and their underlying development drivers. The analysis utilized a comprehensive dataset covering 153,107 individual KESUs across six categories from 2020 to 2024, incorporating distribution patterns across 31 provincial-level regions, 28 industrial classifications of national economic activities, and 18 socioeconomic impact factors. The results showed that KESUs in East China accounted for 41.7% of the total, with the highest concentrations in industrialized cities and economically developed zones. Manufacturing was identified as the dominant industrial classification, with chemical raw materials and products comprising the largest subcategory (13.0% of total KESUs in 2024). Atmosphere KESUs and water KESUs represented the largest proportions, accounting for 29.7% and 25.3% of single-type KESUs, respectively. This study provides a systematic analysis of KESUs, offering a detailed mapping of distribution patterns, emission characteristics, and control challenges for major pollution sources. The findings can provide critical insights to support decision-making aimed at improving regional pollution source management and advancing environmental protection practices.

Arsenic (As) contamination in paddy soils poses a persistent threat to food safety and human health through rice consumption. The environmental fate of As in flooded paddy soils is governed by complex physicochemical and microbially transformations, yet the role of biologically active interfaces remains poorly understood. Periphyton, a ubiquitous and metabolically active biofilm at the paddy soil–water interface, may play a critical role in regulating As speciation and behavior. Herein, we integrated biofilm development, microscopic and elemental characterization, bacterial community profiling, and As-transforming functional gene analysis to elucidate the role of periphyton in As transformation potential. Results showed that periphyton formed a heterogeneous three-dimensional matrix composed of microbial aggregates, extracellular matrix-like materials, and mineral particles. Periphyton-associated As was 2.37 mg kg⁻¹ in the irradiated-soil sample and 1.16 mg kg⁻¹ in the natural-soil sample, whereas dissolved As in the overlying water was 2.06 and 5.85 μg L⁻¹, respectively. The natural-soil composite showed higher bacterial richness and diversity indices than the irradiated-soil composite, with 2615 versus 1124 observed ASVs and Shannon indices of 8.63 versus 7.22. Proteobacteria and Cyanobacteria dominated both communities. The coexistence of aioA, arrA, arsC, and arsM indicated the potential for concurrent As(III) oxidation, As(V) reduction, detoxification, and methylation. In the natural-soil composite, aioA, arrA, and arsM reached 1.84 × 10⁶, 1.99 × 10⁶, and 2.63 × 10⁶ copies g⁻¹ sample, respectively. These values were 2.4-, 9.8-, and 7.2-fold higher than those in the irradiated-soil composite, whereas arsC remained relatively stable. These findings indicate that periphyton provides a structured microbial interface with the genetic potential for multiple As transformation pathways. We propose that paddy periphyton represents a structurally and microbiologically complex interface linking microbial assembly with As-transforming functional potential.