土壤水分和改良剂对镉有效性及温室气体排放的影响

    Effects of Soil Moisture and Amendments on Cadmium Availability and Greenhouse Gas Emissions

    • 摘要: 土壤镉(Cd)污染和温室气体排放是影响土壤质量、农业生产力、人体健康和全球气候变化的2个环境问题, 研究镉污染治理和温室气体减排的土壤改良策略意义重大。生物质炭(CS)因特殊的结构及优良的性能被广泛用作土壤改良剂, 沸石(Zeo)和羟基磷灰石(HAP)因优良的离子吸附能力被普遍应用于重金属污染修复。水分对土壤物理、化学和生物特性有显著影响, 可以改变土壤中镉的迁移和分配从而影响植物对镉的吸收和利用。不同土壤改良剂与水分之间的相互作用可能会共同影响土壤镉有效性和温室气体排放。该研究通过室内试验研究了油茶壳生物质炭、沸石和羟基磷灰石3种土壤改良剂在不同土壤水分条件下对土壤镉有效性及温室气体排放的影响。结果表明, 高外源镉(30 mg·kg-1 CdCl2)浓度下, 添加羟基磷灰石可显著降低土壤N2O排放速率(96.14%~99.18%), 沸石效果次之。添加羟基磷灰石显著降低土壤有效镉含量(43.54%~64.64%), 但显著提高了土壤CO2和CH4排放速率。施加羟基磷灰石可有效治理土壤镉污染, 降低N2O排放速率, 可在酸性镉污染土壤中重点应用。针对CO2和CH4镉污染土壤排放源, 在水分含量较高的土壤中施加沸石效果最佳。未来可以探究羟基磷灰石与其他土壤改良剂的协同效应, 以达到既可减排温室气体, 又可修复土壤镉污染的双重目标。

       

      Abstract: Cadmium (Cd) contamination in soil and greenhouse gas (GHG) emission represent two pressing environmental challenges that affect soil quality, agricultural productivity, human health and global climate dynamics. The development of soil amendment strategies that address both Cd pollution and the reduction of greenhouse gas emission is crucial for enhancing soil quality and promoting the mitigation and sequestration of soil-borne GHGs. Biochar (CS), with its unique structure and superior properties, is extensively employed as a soil amendment. Zeolite (Zeo) and hydroxyapatite (HAP), known for their exceptional ion adsorption capabilities, are also widely utilized in the remediation of heavy metal contamination. Water, a key component for plant growth and development, significantly influences soil physiochemical and biological characteristics, which can change the migration and distribution of Cd in the soil by affecting the soil environment, thus further affecting the absorption and utilization of Cd by plants. The interaction between different amendments and water may jointly impact the bioavailability of soil Cd and the reduction of GHGs, yet the specific effects remain to be elucidated. The effects of three soil amendments of Camellia oleifera shell biochar, zeolite and hydroxyapatite on soil Cd pollution and GHG emissions under different soil water contents were studied through laboratory incubator experiments. The results show that under high external Cd concentration (30 mg·kg-1 CdCl2), HAP significantly reduced the N2O emission rate of soil by 96.14%-99.18%, followed by Zeo. HAP significantly reduced the available Cd content in soil by 43.54%-64.64%, but significantly increased the emission rates of CO2 and CH4. HAP can significantly mitigate soil Cd pollution and reduce the emission rate of N2O, making it a priority for application in acidic Cd-contaminated soils. Zeo has the best remediation effect on soil polluted by Cd from CO2 and CH4 emission sources, especially in soil systems with high water content. Future research should explore the synergistic application of HAP with other soil amendments to achieve the dual objectives of comprehensive GHG emission reduction and soil Cd remediation.

       

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