• 关键词：小麦  镉污染  碱性土壤  锌镉比  阈值

• 基金项目：国家自然科学基金（No.41907353）；中国科学院生态环境研究中心城市与区域生态国家重点实验室项目（No.SKLURE2020-2-5）

• 王天齐
• 1. 中国科学院生态环境研究中心, 城市与区域国家重点实验室, 北京 100085;2. 中国科学院大学, 北京 100049

• 李艳玲
• 1. 中国科学院生态环境研究中心, 城市与区域国家重点实验室, 北京 100085;2. 中国科学院大学, 北京 100049

• 杨阳
• 1. 中国科学院生态环境研究中心, 城市与区域国家重点实验室, 北京 100085

• 戴雅婷
• 1. 中国科学院生态环境研究中心, 城市与区域国家重点实验室, 北京 100085

• 王美娥
• 1. 中国科学院生态环境研究中心, 城市与区域国家重点实验室, 北京 100085

• 陈卫平
• 1. 中国科学院生态环境研究中心, 城市与区域国家重点实验室, 北京 100085;2. 中国科学院大学, 北京 100049

• 摘要：我国北方地区小麦镉(Cd)污染形势严峻.土壤锌(Zn)与Cd存在显著的交互作用,但两者关系尚不明确.本研究通过区域调查及大田实验,探究了北方碱性小麦土壤锌镉比(Zn/Cd)与小麦籽粒Cd含量的相关关系.结果表明,土壤Zn/Cd与小麦籽粒Cd含量显著负相关.施加硫酸锌(增Zn)及深翻耕措施(降Zn)均能显著提高土壤Zn/Cd,并降低小麦籽粒Cd含量.其中,增施100 mg·kg^-1的Zn²⁺,可将土壤Zn/Cd增加61.2%,并使小麦籽粒Cd含量降低9.28%;将土壤0~30 cm及30~60 cm土层互换的深翻耕措施,可将土壤Zn/Cd增加45.8%,并使小麦籽粒Cd含量降低13.5%.综合区域调查及大田实验数据,发现当土壤Zn/Cd小于50时,小麦籽粒Cd含量全部超标且有98.4%的样品超标1倍以上;而当土壤Zn/Cd大于100时,小麦籽粒Cd含量超标风险显著降低至11.9%.该阈值的确定对于小麦Cd污染防治具有指导意义.

• Abstract：Cadmium (Cd) accumulation in wheat grain poses significant public health risk. Interactions between soil Cd and Zn occur in terms of wheat uptake, while their relationship is not clear. In this study, the Cd and Zn concentrations of wheat grain as well as soils from production fields in north China were investigated. A significant and negative correlation between soil Zn to Cd ratio (Zn/Cd) and wheat grain Cd was observed. Application of zinc sulfate (increase of soil Zn) and intensive tillage (decrease of soil Zn) significantly increased soil Zn/Cd and reduced Cd in wheat grains. Application of 100 mg·kg^-1 Zn²⁺ caused an increase of soil Zn/Cd by 61.2% and a decrease of grain Cd concentration by 9.28%. The intensive tillage, switching soil layers of 0~30 cm and 30~60 cm, caused an increase of soil Zn/Cd by 45.8% and a decrease of grain Cd concentration by 13.5%. The soil Zn/Cd threshold value of 50 and 100 was proposed. When soil Zn/Cd was less than the threshold value of 50, there is a 98.4% probability that the grain Cd concentration would exceed the corresponding limit. This risk was significantly decreased to 11.9% when the soil Zn/Cd raised to 100 and above. Proposed threshold values of Zn/Cd in wheat soils help safeguard the production of safe-to-consume grain in the study region.

• Key words：wheat  cadmium pollution  alkaline soil  zinc-to-cadmium ratio  threshold value

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