互花米草生物炭的添加对土壤吸附三氯生的影响及其机制研究

Effects of addition of Spartina alterniflora-derived biochars on the sorption of triclosan by soil and their mechanisms

互花米草作为入侵物种,在我国沿海分布广泛,对沿海生态造成负面影响.本研究以互花米草资源化利用为出发点,在300℃和600℃下将其热解分别制得BC300和BC600两种生物炭,采用批量平衡法研究了生物炭添加对土壤吸附三氯生(TCS)的影响及其机制.结果表明,BC300内含有未炭化有机质,对TCS的吸附以分配作用为主,有利于对高浓度TCS的吸附;BC600有较大的比表面积,对TCS的吸附以表面吸附为主,有利于对低浓度TCS的吸附.生物炭添加能够促进土壤对TCS的吸附,且吸附量随生物炭添加比例的增加而增加;添加BC300的土壤对TCS的吸附量要显著高于添加BC600的土壤,这主要与生物炭的结构特征及其对土壤p H值的影响有关.因此,添加300℃下制备的互花米草生物炭可以有效地降低土壤中TCS的环境风险,同时也能为护花米草的资源化利用提供一条可行途径.

As an invasive species widely distributed in coastal areas of China,Spartina alterniflora inevitably induces negative impacts on the coastal ecosystem. Based on the resource utilization of Spartina alterniflora,two types of biochars（ BC300 and BC600） were produced from it under pyrolysis at the temperatures of 300 ℃ and 600 ℃,respectively,in this study. The effects of biochars addition on the sorption of triclosan（ TCS） by soil and their mechanisms were investigated using batch experiments. The results showed that the non-carbonated organic matter in BC300 was in favor of the sorption of TCS at high concentrations mainly via partition mechanisms,while the high specific surface area of BC600 was in favor of the sorption of TCS at low concentration mainly via the surface adsorption. Biochar addition enhanced the sorption of TCS by soil,and the sorption capacity of soil for TCS increased with the increasing proportion of biochar in soil. The sorption quantity of TCS on the soil with BC300 addition was greater than the soil with BC600 addition,which was due to the different structural characteristics of the two biochars and their effects on soil p H. Therefore,addition of the biochar produced from Spartina alterniflora at 300 ℃ can effectively reduce the environmental risks of TCS in soil,which also provide an effective method forresource utilization of Spartina alterniflora.