两种生物炭对两种质地土壤中阿特拉津淋溶与迁移的影响

Effect of Two Biochars on Leaching and Migration of Atrazine in Two Soils

通过室内培养和模拟土柱淋溶实验,研究了在500℃热解温度下制备的甘蔗叶生物炭和蚕沙生物炭对阿特拉津在冲积土(砂土)和潮土(粘土)中淋溶与迁移的影响,两种生物炭的添加比例分别为0.2%和0.5%,污染土中AT的浓度为10 mg·kg-1。结果表明,添加生物炭显著增加了表层土壤的阳离子交换量和有机碳的含量,明显抑制了阿特拉津在土柱中的淋溶与迁移。在同一种土壤中,生物炭添加量相同时,甘蔗叶生物炭对土壤中阿特拉津的淋溶与迁移抑制效果较蚕沙炭明显,并且同一种生物炭添加量越高,抑制作用越明显。对比两种质地土壤中阿特拉津的淋出率发现,生物炭的加入对抑制粘土中阿特拉津的淋溶与迁移作用更明显。相关性分析结果表明,土柱表层土壤的阳离子交换量、有机碳含量与底层土壤阿特拉津含量、淋溶液阿特拉津累积量均呈显著负相关。可见,生物炭的添加可以明显固定土壤中的阿特拉津,减少其淋溶与迁移,有效修复阿特拉津污染的土壤,控制其对地下水的污染。

Herbicides in soils can easily enter the surface water and groundwater through run off and leaching, leading to water pollution. A simulation experiment was performed to study the effects of biochar amendments on the transport of atrazine in soils. Two biochars, sugar-cane top(BCst)and silkworm excrement(BCse), were produced under pyrolysis temperature at 500 ℃ and limited oxygen. The biochars were added at 0.2% and 0.5% rates to two soils, sandy soil and clay soil, pre-polluted with 10 mg·kg-1atrazine. Biochar addition changed the basic physiochemical properties of soils. Soil organic carbon(SOC)and cation exchange capacity(CEC)were significantly increased by biochars, compared with the control. Biochars inhibited the transport of atrazine in soil, with greater effects in BCst than in SCse. The stronger adsorption and less transport of atrazine were observed in the soils with higher biochar additions. The leaching rate of atrazine was greater in sandy soil than in clayey soil. Correlation analysis suggested that SOC and CEC in the top soil(0~5 cm)had significantly negative relationship with the content of atrazine in the subsoil(15~20 cm)and the leaching of atrazine into groundwater. These results suggest that biochars could be used as artificially adsorbent to efficiently control the migration and leaching of atrazine in soils.