## 4 Conclusions  
With an average concentration of Cd 0.12 mg/kg, Cd levels in Hainan's agricultural soils are 2.14 times higher than the natural background value of 0.056 mg/kg, and although they remain below the regulatory threshold of 0.30 mg/kg established by GB 15618-2018,  
Figure 10: Ranking of Cd risk factors based on the q-Statistic. localized areas exhibit severe contamination, with maximum concentrations of 3.11 mg/kg, 10.37 times than the threshold. The spatial analysis of Cd levels reveals a heterogeneous distribution across Hainan Island, with relatively lower concentrations in central counties like Baisha and Tunchang, whereas urbanized and agriculturally intensive regions, such as Haikou, Danzhou, and Sanya, exhibit elevated contamination. While most areas remain within unpolluted to moderately polluted categories, 2.17% of sampling points show heavy to extreme Cd accumulation, and 2.13% fall into high ecological risk zones (Level IV). These high-risk zones require immediate intervention to mitigate potential ecological and agricultural impacts. These regional differences stem from both natural geological factors and anthropogenic influences. In certain northern areas of Hainan, elevated natural background Cd levels contribute to higher soil concentrations. However, human activities remain the dominant driver of Cd accumulation. Rapid urbanization, industrialization, and tourism expansion in Haikou and Sanya have led to increased anthropogenic emissions, including waste disposal and construction, industrial, and mining activities. Additionally, long-term agricultural practices, particularly the application of phosphate fertilizers with varying Cd content, have exacerbated Cd accumulation in agricultural soils. Temporal data spanning from 2005 to 2023 indicate a discernible increase in Cd levels in agricultural soils, with mean concentrations rising from 0.09 mg/kg in earlier years to 0.16 mg/kg in more recent assessments, reflecting intensified anthropogenic influences. The exceedance rate also escalated from approximately 1% to over 20% in some years. This increase correlates with intensified anthropogenic activities, including the use of tailings and the widespread application of phosphate fertilizers, both of which are primary contributors to Cd accumulation in soils. Despite adhering to regulatory safety thresholds overall, hotspots of excessive Cd accumulation highlight the need for reinforced monitoring and targeted mitigation efforts to curb further contamination risks. The risk of Cd contamination in agricultural soils has shifted from predominantly geogenic influences to a complex mix of agricultural, industrial, and transportation-related sources. Pesticide application, phosphate fertilizer use, industrial emissions, and transportation activities are the main contributors to Cd accumulation. These findings emphasize the urgent need for targeted mitigation strategies, enhanced monitoring, and sustainable agricultural practices to ensure the long-term sustainability of agricultural production on Hainan Island. Future research should focus on quantifying and tracking Cd pollution sources, optimizing pesticide and fertilizer use to minimize heavy metal inputs, and implementing precision agriculture to further reduce contamination risks. These efforts are crucial for protecting soil health, maintaining sustainable agricultural practices, and reducing ecological risks linked to Cd pollution. The following supporting information can be downloaded at: [[https://www.mdpi.com/article/10.3390/app15073817/s1](https://www.mdpi.com/article/10.3390/app15073817/s1)]([https://www.mdpi.com/article/10.3390/app15073817/s1](https://www.mdpi.com/article/10.3390/app15073817/s1)), Figure S1: Co-occurrence Map (publications); Figure S2: Keyword- publications Timeline Map; Figure S3: Spatial distribution map of pollution risk factors; Table S1: The references for meta-analysis; Table S2: Data Sources for Pollution Source Factors. Data curation, S.Z., E.S. and A.L. ; writing--original draft preparation, E.S.