钝化剂对轻中度镉污染农田的安全利用效果

为研究酸性镉（Cd）污染土壤安全利用问题，以陕西商洛轻中度Cd污染农田为研究对象，分别施加生石灰、生物炭和钙镁磷肥，通过小麦-玉米轮作试验，探究不同用量钝化剂对Cd污染土壤的安全利用效果，筛选出最佳的钝化剂配比.结果表明：①通过钝化剂的施加，能不同程度地改善土壤质量.②施用钝化剂后，小麦和玉米的籽粒产量均有不同程度地提高.③3种钝化剂可有效地提升土壤pH值和降低土壤有效态Cd含量，生石灰2 340 kg·hm^-2（C3）处理效果最佳，分别增加小麦和玉米土壤pH 1.453和1.717单位，减少有效态Cd含量34.38%和30.20%.④施加生物炭1 800 kg·hm^-2（B2）处理对降低小麦根系、秸秆和籽粒Cd含量效果最好，较CK分别显著降低了53.60%、38.86%和52.96%，其小麦籽粒ω（Cd）降低至0.09 mg·kg^-1，低于《食品安全国家标准 食品中污染物限量》（GB 2762-2017）中规定的小麦Cd限量值（0.1 mg·kg^-1）；施加生物炭1 260 kg·hm^-2（B1）处理对降低玉米根系、秸秆和籽粒Cd含量综合效果最佳，较CK分别显著降低43.74%、53.20%和94.57%，其玉米籽粒ω（Cd）降低至0.001 9 mg·kg^-1，远低于《食品安全国家标准 食品中污染物限量》（GB 2762-2017）中规定的玉米Cd限量值（0.1 mg·kg^-1）.因此，在田间试验条件下，综合考虑各项指标的影响，生物炭在轻中度Cd污染的小麦-玉米轮作区农田土壤效果最好.

Safe Utilization Effect of Passivator on Mild to Moderate Cadmium Contaminated Farmland

In order to study the safe utilization of acid cadmium （Cd） contaminated soil， light and moderate Cd-contaminated farmland in Shangluo， Shaanxi Province was taken as the research object， and lime， biochar， and calcium magnesium phosphate fertilizer were applied. Through the wheat-maize rotation experiment， the safe utilization effect of different amounts of passivator on Cd-contaminated soil was explored， and the best ratio of passivator was selected. The results showed that： ① the soil quality could be improved to varying degrees by applying the passivator. ② After the application of amendments， the grain yield of wheat and maize increased to different degrees. ③ The lime 2 340 kg·hm^-2 （C3） treatment had the best effect， which increased the soil pH of wheat and corn by 1.453 and 1.717 units， respectively， and reduced the available Cd content by 34.38% and 30.20%， respectively. ④ The application of biochar 1 800 kg·hm^-2 （B2） treatment had the best effect on reducing the Cd contents in wheat roots， straws， and grains， which were significantly reduced by 53.60%， 38.86%， and 52.96%， respectively， compared with that in CK. The Cd content in wheat grains was reduced to 0.09 mg·kg^-1， which was lower than the limit value of wheat Cd （0.1 mg·kg^-1） specified in the “National food safety standard food pollutant limit” （GB 2762-2017）. The application of the biochar 1 260 kg·hm^-2 （B1） treatment had the best comprehensive effect on reducing the Cd contents of maize roots， straws， and grains， which were significantly reduced by 43.74%， 53.20%， and 94.57%， respectively， compared with that in CK. The Cd content of maize grains was reduced to 0.001 9 mg·kg^-1， which was far lower than the limit value of maize Cd （0.1 mg·kg^-1） specified in the "National food safety standard food pollutant limit" （GB 2762-2017）. Therefore， under the conditions of the field experiment， considering the influence of various indexes， biochar had the best effect on farmland soil in the wheat-maize rotation area with mild to moderate Cd pollution.