Boostani Hamid Reza, Hardie Ailsa G, Najafi-Ghiri Mahdi, Zare Morteza
Department of Soil Science, College of Agriculture and Natural Resources of Darab, Shiraz University, Darab, Iran.
Department of Soil Science, Faculty of AgriSciences, Stellenbosch University, Private Bag X1, Matieland, 7602, South Africa.
Environ Geochem Health. 2023 Jan;45(1):199-213. doi: 10.1007/s10653-022-01289-7. Epub 2022 May 28.
Biochars vary widely in properties and have been shown to have variable effects on potentially toxic element(s) stabilization in soil. This is the first study to examine the interaction effects of biochar and soil moisture regime on Ni stabilization in a Ni-contaminated calcareous soil. Three different organic waste (cow manure, municipal compost and licorice root pulp) biochars produced at two temperatures (300 and 600 °C) were applied (3% wt.) to a Ni-contaminated calcareous soil and incubated at field capacity and saturated conditions for 70 d. Sequential chemical fractionation and Ni release kinetics were then performed. All applied biochars, especially the high-temperature biochars, were significantly able to enhance Ni stabilization in the studied soil. In particular, the biochars significantly decreased Ni content in the water-soluble and exchangeable fractions (10-42% decrease), while increasing the immobile residual fraction (13-38% increase). The biochars also significantly decreased the rate and cumulative amount of EDTA-extractable Ni from the calcareous soil. Among the studied biochars, the cow manure and municipal compost biochars produced at 600 °C were the most effective at reducing Ni mobility factor (27-28% decrease) and initial release rate (42-49% decrease), likely due to their high ash content and pH, which promotes Ni sorption in soil. Soil moisture regime was not found to significantly affect the Ni mobility factor or rates of Ni release from the calcareous soil but did, however, affect certain soil Ni chemical fractions. Soil water saturation significantly decreased Ni in the Mn (4%) and non-crystalline Fe oxides (17%) fractions, while increased the crystalline Fe oxide fraction (3%), attributed to reductive dissolution of Mn and Fe oxide crystallinity enhancement. Saturation also significantly enhanced Ni in the residual fraction (4%), attributed to the associated pH increase and potential sulfide formation. The results of this study demonstrate that high temperature, ash-rich, and alkaline biochars are most effective at Ni immobilization, and that soil water saturation can further enhance Ni in the residual fraction.
生物炭的性质差异很大，并且已证明其对土壤中潜在有毒元素的稳定化具有不同的影响。这是第一项研究生物炭与土壤水分状况对镍污染石灰性土壤中镍稳定化的交互作用的研究。将在两种温度（300和600°C）下制备的三种不同有机废物（牛粪、城市堆肥和甘草根浆）生物炭（按重量计3%）施用于镍污染的石灰性土壤，并在田间持水量和饱和条件下培养70天。然后进行连续化学分级和镍释放动力学研究。所有施用的生物炭，尤其是高温生物炭，均能显著增强所研究土壤中镍的稳定性。特别是，生物炭显著降低了水溶性和可交换态部分的镍含量（降低10 - 42%），同时增加了难移动的残留态部分（增加13 - 38%）。生物炭还显著降低了石灰性土壤中EDTA可提取镍的速率和累积量。在所研究的生物炭中，600°C下制备的牛粪和城市堆肥生物炭在降低镍迁移因子（降低27 - 28%）和初始释放速率（降低42 - 49%）方面最有效，这可能归因于它们的高灰分含量和pH值，有利于土壤中镍吸附。未发现土壤水分状况对石灰性土壤中镍迁移因子或镍释放速率有显著影响，但确实影响了某些土壤镍化学组分。土壤水饱和显著降低了锰（4%）和非晶态铁氧化物（17%）部分中的镍含量，同时增加了晶态铁氧化物部分（3%），这归因于锰的还原溶解和铁氧化物结晶度增强。饱和还显著增加了残留态部分中的镍含量（4%），这归因于相关的pH值升高和潜在的硫化物形成。本研究结果表明，高温、富灰分和碱性生物炭对镍固定最有效，并且土壤水饱和可进一步增加残留态部分中的镍含量。
