磷酸改性生物炭和氯混施对土壤铅形态及小麦铅吸收的影响

通过盆栽试验研究磷酸改性生物炭和氯混施对石灰性污染土壤有效铅含量、铅化学形态及小麦各部位(籽粒、颖壳、茎叶、根)铅含量分布的影响。结果表明:施用改性生物炭(50、100 g·kg~(-1))虽然降低土壤pH,但也可以显著降低有效态铅的含量。就土壤中铅的化学形态而言,改性生物炭降低土壤中弱酸提取态铅和还原态铅含量,同时增加了氧化态、残渣态铅含量。此外,磷酸改性生物炭和氯混施后小麦各部位铅含量显著降低。研究证实,氯对改性生物炭修复铅污染土壤有促进作用,可以进一步降低土壤有效态铅含量,这一效果以添加CaCl_2更佳。高剂量改性生物炭配施低剂量CaCl_2后,小麦籽粒铅含量降至0.16 mg·kg~(-1),符合《粮食卫生标准》(GB 2715—2016)。

Effects of phosphoric-acid-modified biochar combined with chlorine on soil lead form and lead absorption in wheat

Pot experiments were conducted to investigate the effects of phosphoric-acid-modified biochar combined with chlorine on the content of available lead and its various chemical forms in contaminated calcareous soil. Moreover, the distribution of Pb content in different parts of wheat(grain, glume, stem leaf, and root) was studied. The results showed that the content of available Pb in the soil decreased, although modified-biochar treatment(both 50 g·kg^-1 and 100 g·kg^-1) significantly decreased soil pH. With respect to the chemical forms of Pb in the soil, biochar treatment reduced the contents of acid-extractable and reducible Pb in the soil and increased those of oxidized and residual Pb. Moreover, the modified biochar combined with chlorine significantly reduced the Pb content in different parts of the wheat. This study confirmed that addition of chlorine can enhance the remediation efficiency of modified biochar for Pb-contaminated soil, decreasing the content of soil-available Pb. The remediation efficiency was better with CaCl₂ addition. The Pb content of wheat grain decreased to 0.16 mg·kg^-1 with treatment using high concentration of modified biochar combined with low CaCl₂ concentration, which meets the "food hygiene standard" GB 2715-2016.