水作和旱作施用改良剂对蕹菜-土壤系统中铅镉生物有效性的影响差异

为探讨不同农艺调控措施组合对蔬菜-土壤系统重金属生物有效性的影响,以能同时适应水作和旱作两种栽培方式的蕹菜为研究对象,探讨了在人为添加铅镉复合污染情况下,不同栽培方式和施用改良剂(石灰或生物炭)的农艺调控措施组合对蕹菜中铅镉累积规律的影响差异,并从不同处理情况下的土壤理化性质和重金属有效态含量变化特征等方面分析其作用机理。结果发现,旱作和水作两种栽培方式下,蕹菜中重金属累积及土壤重金属有效性等方面出现了不同的变化规律:在水作条件下施用石灰比旱作能更有效地降低土壤铅镉有效态含量,而水作条件下施用石灰和生物炭均能在提高蕹菜产量的情况下降低蕹菜中铅镉含量,且施用6 g·kg~(-1)生物炭的效果最优。总的来说,与旱作模式相比,水作条件下施用改良剂往往对蕹菜-土壤系统中铅镉累积特性的影响效果更明显。

Comparing the effects of soil amendments on Pb and Cd bioavailability in water spinach under water submersion cultivation and dry farming conditions

To study the effects of different agronomic measures on heavy metal bioavailability in vegetable-soil systems, in this study, water spinach, which can adapt to both water submersion cultivation and dry farming conditions, was chosen as the research subject. The aim of the study was to compare the effects of applying soil amendments(lime or biochar) on Pb and Cd accumulation by water spinach using different cultivation methods in the soil artificially polluted with a combination of high concentrations of Pb and Cd. In addition, the changes in soil physical and chemical properties and available heavy metal contents under different agronomic measures were analyzed to reveal the influential mechanisms. It turned out that under the two cultivation methods, water spinach showed different accumulation effects of heavy metals and soil heavy metal availabilities. Applying lime under water submersion cultivation conditions could reduce the available contents of Pb and Cd in soil more effectively than that under dry farming conditions. Additionally, under water submersion cultivation conditions, applying both lime and biochar could reduce the Pb and Cd contents in vegetables as the yield increased, but the effect of applying 6 g biochar·kg^-1 soil was the best. In summary, compared with dry farming, applying soil amendments under water submersion cultivation conditions could affect Pb and Cd accumulation characteristics in the soil-plant system more.