Policy Adjustments: Their Dual Impacts and Sustainability Assessment on Heavy Metal Concentration in Topsoil of Nantong City, China

Soil heavy metal pollution has emerged as a substantial threat to environmental quality and human health. The pollution levels of heavy metals in soil are significantly influenced by human activities, rendering it one of the most crucial topics for the sustainable development of soils. This study analyzed the data of surface soil heavy metal concentration in Nantong from 2008 to 2018 to explore the impact of policy adjustments on concentration levels. The results revealed that over the past decade, the overall content of Pb in the topsoil of Nantong decreased by 32.41%, presumably attributed to the widespread use of unleaded petrol. This suggests that policy adjustments can effectively regulate heavy metal pollution levels. However, the average concentration of Cr increased by 68.03%, and the high-concentration center shifted from the southwestern to the northeastern part of Nantong. The large-scale relocation of factories from riverside to coastal areas in Nantong likely contributed to this phenomenon. Evidently, the changes in heavy metal concentration in surface soils clearly exhibited policy-driven characteristics. Therefore, it is recommended that when formulating or adjusting relevant policies, it is imperative to comprehensively consider their potential impacts on soil heavy metal contamination. This is crucial for ensuring the overall effectiveness of the policies in terms of the sustainability of the soil environment. This article provides valuable insights for understanding heavy metal accumulation in Nantong and offers guidance for promoting future industrial upgrading and strategic planning, which is of great significance in guiding the improvement in soil quality and ensuring its sustainable use.