Agro-Environmental Protection Institute, Ministry of Agriculture and Rural Affairs, Tianjin 300191, China.
Beijing Municipal Key Laboratory of Agriculture Environment Monitoring, Beijing 100097, China.
Int J Environ Res Public Health. 2022 May 27;19(11):6561. doi: 10.3390/ijerph19116561.
The study of threshold levels of heavy metals in soil is essential for the assessment and management of soil environmental quality. This study reviewed the influencing factors, the derivation, and application aspects of heavy metals' threshold values comprehensively by a combination of bibliometric analysis and scientific knowledge mapping. A total of 1106 related studies were comprehensively extracted from the Web of Science database during the period from 2001 to 2020. The results showed that the publication output has been growing strongly. An analysis on the subject, journal, country, and institution was carried out to demonstrate the development and evolution of this research branch during the two decades. According to high-frequency keywords analysis, external factors (e.g., soil physicochemical properties) and internal factors (e.g., crop genotype) can affect heavy metal threshold values in the soil-crop system. The current methods mainly include the Point model (e.g., evaluation factor method), the Probability model (e.g., species sensitivity distribution method), and the Empirical model (e.g., ecological environment effect method). A threshold study can be applicable to the risk assessment for soil heavy metal contamination in order to determinate the soil pollution degree and its spatial and temporal distribution characteristics. Moreover, challenges and prospects of the study of heavy metal threshold values are proposed, indicating that research should focus on the relationships between human health risks and the established threshold values of heavy metals in the soil, long-term field trials and bioavailability of heavy metals for the derivation of the thresholds, and the establishment of more scientific and rational soil environmental benchmarks.
研究土壤重金属的阈值水平对于评估和管理土壤环境质量至关重要。本研究通过文献计量分析和科学知识图谱相结合的方法，全面综述了重金属阈值的影响因素、推导和应用方面。综合从 Web of Science 数据库中全面提取了 2001 年至 2020 年期间的 1106 篇相关研究。结果表明，该领域的研究成果呈强劲增长趋势。对主题、期刊、国家和机构进行了分析，以展示这一研究分支在过去二十年的发展和演变。根据高频关键词分析，土壤-作物系统中的重金属阈值受到外部因素（如土壤理化性质）和内部因素（如作物基因型）的影响。目前的方法主要包括点模型（如评价因子法）、概率模型（如物种敏感性分布法）和经验模型（如生态环境效应法）。阈值研究可应用于土壤重金属污染风险评估，以确定土壤污染程度及其时空分布特征。此外，还提出了重金属阈值研究的挑战和展望，表明研究应重点关注土壤中重金属的建立阈值与人类健康风险之间的关系、长期田间试验和重金属的生物有效性对于阈值的推导、以及更科学和合理的土壤环境基准的建立。
