Rapid urbanization and industrial growth in China have increased brownfield site reclamation, the sustainable remediation for urban transformation and enhancing ecosystem services. However, traditional brownfield safety assessment strategies impose unnecessary costs since excessive remediation. Herein, a comprehensive system integrated by soil self-purification, potential ecological risks and human health risks is developed to investigate the safety of brownfield sites. Indices, including soil environmental loading capacity (SELC), and Nemerow integrated pollution index (NIPI), were introduced to assess heavy metals (HMs) pollution. Results show that 72.05% of the sites are identified as moderate pollution, where Cd, As, and Cr(VI) are at heavy pollution, incorporating soil self-purification. The average values of potential ecological risk (PERI) reached 6615.00, posing a significant damage to the local ecosystem, and Cd was identified as main ecological hazards in the study sites. Furthermore, the health risk assessment shows that children's health risks are higher than that of adults, with non-carcinogenic risk to children (2.60) and adults (0.41), and carcinogenic risk to children (2.30 x 10-3) and adults (1.12 x 10-4). Utilizing a multi-index decision-making approach, it is determined that 19.30% of the site exhibit high-risk values, between concentration screening (11.40%) and risk screening (83.30%) base on single-indices. The study sheds light on the comprehensive assessment of brownfield site safety.

To remedy ecological damage and soil contamination in mining brownfields, this research focuses on the Gumi Mountain mining area in Wuhan. It proposes restoration strategies based on Nature-based Solutions (NbSs). Besides terrain restoration and soil enhancement, it also involves the redesigning of water systems, hydrological management, and the stratified planting of native species to restore plant communities. As China's inaugural quartz optical fiber was born here, we need to consider its history when making reclamation strategy for the Optics Valley City. This research took the Pulsed High Magnetic Field Facility (PHMFF) as the prototype to build a model that integrates mountain, river, forest, farmland and flower ecosystems. Based on NbS, we divided the brownfield by functions and redesigned the tourist routes. This research offers new methodologies for similar efforts in mine rehabilitation.

This study carries out the first evaluation of the impacts of ravines and gullies in urban areas in Brazil considering environmental damage, such as costs related to land restoration and erosion control, infrastructure destruction, economic losses and income losses related to property and urban land taxes. In this study, the city of Bauru, Brazil, has been selected as study site, where three areas were chosen due to the large impact that ravines and gullies have caused over the past two decades. Our analysis indicates that the total damage exceeds US$ 173 million and is mainly related to land degradation. The cost of replacing the eroded soil in these three areas is estimated at approximately US$ 13.3 million. Furthermore, according to our analysis, urban areas affected by ravines and gullies represent problems similar to brownfields. The assessment of the impacts and challenges associated with urban ravines and gullies can help promote accountability by those responsible for their initiation and may contribute to decreasing the development of new eroded areas.