沙蒿生物质炭在沙土中的降解特征

Degradation Characteristics of Artemisia ordosica Biochar in Sandy Soil

为明确不同炭化条件下沙蒿生物质炭的有机组分、炭化过程和降解特性。于不同炭化条件下无氧炭化制备沙蒿生物质炭并进行沙地封存。结果表明:H、O和N元素的质量分数及H/C、O/C和(N+O)/C均随炭化温度的升高和炭化时间的延长呈先降低后稳定的变化趋势,升温速率对其无显著影响。而C则呈相反趋势且均在炭化温度>600℃、炭化时间>60 min以后基本达定值,上述指标(H、O、N、H/C、O/C、(N+O)/C和C)的稳定值分别约为29.3 g/kg、79.8 g/kg、11.2 g/kg、0.40、0.07、0.08和879.7 g/kg。生物质炭的降解速率随着炭化温度的升高、炭化时间的延长和施用量的增大而降低,其半衰期为2~12年。综上,沙蒿的炭化既是有机组分富碳、去极性官能团的过程,同时也是芳香性增强、亲水性和极性减弱的过程,施用量和炭化温度是影响生物质炭降解的决定性因素。

Artemisia ordosica biochars were prepared under anaerobic carbonization condition at different temperatures and added into the sand in order to identify their organic components, carbonization process and degradation characteristics under different carbonization conditions. The results showed that the mass fraction of H, O and N elements, H/C, O/C and（N ＋ O）/Cdecreased first and then tended to stable with the increase of temperature and carbonization time, but they were not affected obviously by the heating rate, while C showed the opposite trend and it was near stabilized after carbonization temperature 600 ℃, the carbonized time 60 min. The stable values of the above indexes were about 29.3 g/kg, 79.8 g/kg, 11.2 g/kg, 0.40, 0.07, 0.08 and 879.7 g/kg, respectively. Degradation rate of biochar was reduced with the increased carbonization temperature, extended carbonization time and increased amount of biochar, its half-life was about 2—12 years. In conclusion, the biomass heating pyrolysis is a process in which carbon enriched and polar functional groups cut, meanwhile aromaticity increased but hydrophilic and polarity weakened, and application amount and carbonization temperature are the decisive factors in influencing degradation of biochar.