农田重金属污染长期演变LIVE模型构建  

Modeling the Long-term Evolving Features of Heavy Metal Concentration in Agricultural Soil

作　　者：王刘炜 侯德义[1] WANG Liu-wei;HOU De-yi(School of Environment,Tsinghua University,Beijing 100084,China)

机构地区：[1]清华大学环境学院,北京100084

出　　处：《土壤通报》2022年第6期1471-1480,共10页Chinese Journal of Soil Science

基　　金：国家自然科学基金项目(42077118);国家重点研发计划项目(2020YFC1808000)资助。

摘　　要：【目的】我国农田重金属污染较为突出,严重威胁农产品安全。防范农田土壤重金属的长期累积增加、实现农田土壤可持续的安全利用,是保障粮食安全生产的重要前提。然而现有政策管理框架与实践重点关注已污染农田土壤的风险管控与修复,侧重重金属污染农田的高效、短期安全利用,对重金属浓度在较长时间尺度内的动态变化重视不足。针对农田重金属长期的演变规律,亟需建立有效的预测方法,为相关政策的制定提供决策支撑。【方法】基于重金属元素的入流与出流特征分析与质量衡算,构建了农田土壤重金属演变规律预测的LIVE(Long-term Influx Versus Efflux)模型。通过选取典型参数,模拟浅层与深层农田土壤中镉(Cd)、砷(As)典型污染物的长期演变规律。【结果】农田重金属的变化规律可分为单向、波动、突变等多种形式。进一步结合长期观测数据,对不同演变规律的形成原因进行了探讨。【结论】在各入流项与出流项相对恒定的理想情形下重金属的积累存在单向性特征;水通量的波动性间接导致了污染物积累的波动性特征;通过人为控源,可以明显遏制乃至扭转重金属元素的积累,使污染物含量呈现突变性特征。该模型能够为重金属污染农田土壤长期、有效的安全利用提供相应依据。[Objective] Heavy metal contamination of agricultural soils threatens food security. It’s imperative to seek effective methods to assure the safe production of crops. Understanding the long-term accumulation/loss patterns of heavy metals is crucial for the sustainable use of agricultural soils. Although many successful attempts have been made regarding the safe utilization of contaminated agricultural soils using either risk control or remediation approaches, the dynamic evolving nature of soil heavy metals in the long run had been neglected. Therefore it’s crucial to develop an effective method to predict metal accumulation patterns. [Method] This study developed a Long-term Influx Versus Efflux(LIVE) model to assess the long-term evolving features of heavy metals in agricultural soils on the basis of mass balance calculations. Typical values of various inputs and outputs were selected, after which the accumulation behaviors of representative contaminants, namely, Cd and As were assessed. [Result] Representative evolving patterns of soil metal concentrations are put forward, namely, unidirectional, fluctuating, and suddenly changing. These patterns are further verified with previously reported field monitoring data. [Conclusion] Constant influx and efflux result in an unidirectional pattern, fluctuation in water flux leads to fluctuation in soil metal concentration, while source control of metal input can mitigate or even reverse the trend of metal accumulation immediately. The results will shed lights on the long-term safe utilization for contaminated agricultural soils.

关 键 词：重金属 老化 波动 污水灌溉 长期监测 

分 类 号：X53[环境科学与工程—环境工程]