School of Materials Science and Engineering, The University of New South Wales, Sydney, NSW 2052, Australia.
Chemosphere. 2012 Apr;87(2):151-7. doi: 10.1016/j.chemosphere.2011.12.007. Epub 2012 Jan 9.
Biochar, as a soil amendment, can increase concentrations of soil organic matter, especially water-extractable organic carbon (WEOC). This can affect the adsorption-desorption equilibrium between the dissolved solid phases in soil organic matter. Dissolved organic carbon (DOC) represents a small proportion of soil organic matter, but is of significant importance in the soil ecosystem due to its mobility and reactivity. Here, water extracts obtained from twelve non-herbaceous biochars (before, and after, chemical treatment with either H(3)PO(4) or KOH), were tested by Liquid Chromatography - Organic Carbon Detection (LC-OCD) to identify the effects of both pyrolysis conditions and chemical treatments on WEOC content. LC-OCD has the capacity to provide a fingerprint of WEOC, which allows analysis of the various fractions present. WEOC content was affected by both the pyrolysis temperature and the feedstock used. High mineral ash contents deriving from the feedstock can prompt thermochemical reactions of lignocelluloses to produce a relatively high WEOC content, which includes low molecular weight neutrals and humic acids as dominant components. A significant change in WEOC occurred during pyrolysis due to secondary reactions which resulted in a much lower WEOC in the high temperature biochars where fractions of low molecular weight acids and neutrals are dominant. Chemical treatments with H(3)PO(4) or KOH increased WEOC concentration, possibly by promoting hydrolysis reactions on biochar surfaces. These observations assist in assessing the contribution of biochar additions to the soil ecosystem and demonstrate the utility of LC-OCD in providing an understanding of how biochar additions to soil can alter DOC.
生物炭作为一种土壤改良剂，可以增加土壤有机质的浓度，特别是水可提取有机碳（WEOC）。这可能会影响土壤有机质中溶解固相之间的吸附-解吸平衡。溶解有机碳（DOC）虽然只占土壤有机质的一小部分，但由于其流动性和反应性，在土壤生态系统中具有重要意义。在这里，通过液相色谱-有机碳检测（LC-OCD）对 12 种非草本生物炭（在用 H（3）PO（4）或 KOH 进行化学处理之前和之后）获得的水提取物进行了测试，以研究热解条件和化学处理对 WEOC 含量的影响。LC-OCD 有能力提供 WEOC 的指纹图谱，从而可以分析存在的各种组分。WEOC 含量既受热解温度又受原料的影响。高矿物灰分来源于原料，可以促进木质纤维素的热化学反应，产生相对较高的 WEOC 含量，其中包括低分子量中性物和腐殖酸作为主要成分。由于次生反应，WEOC 在热解过程中发生了显著变化，导致高温生物炭中的 WEOC 含量大大降低，其中低分子量酸和中性物的分数占主导地位。用 H（3）PO（4）或 KOH 进行化学处理会增加 WEOC 浓度，这可能是通过促进生物炭表面的水解反应实现的。这些观察结果有助于评估生物炭添加对土壤生态系统的贡献，并展示了 LC-OCD 在提供理解生物炭添加如何改变土壤 DOC 方面的效用。
