Norwegian Geotechnical Institute (NGI), P.O. Box 3930, Ullevål Stadion, NO-0806 Oslo, Norway; Department of Chemistry, University of Oslo (UiO), P.O. Box 1033, Blindern, NO-0315 Oslo, Norway.
Norwegian Geotechnical Institute (NGI), P.O. Box 3930, Ullevål Stadion, NO-0806 Oslo, Norway.
Chemosphere. 2016 Jan;142:100-5. doi: 10.1016/j.chemosphere.2015.04.087. Epub 2015 May 13.
Amendments of biochar, a product of pyrolysis of biomass, have been shown to increase fertility of acidic soils by enhancing soil properties such as pH, cation-exchange-capacity and water-holding-capacity. These parameters are important in the context of natural organic matter contained in soils, of which dissolved organic matter (DOM) is the mobile and most bioavailable fraction. The effect of biochar on the content and composition of DOM in soils has received little research attention. This study focuses on the effects of amendments of two different biochars to an acidic acrisol and a pH-neutral brown soil. A batch experiment showed that mixing biochar with the acrisols at a 10 wt.% dose increased the pH from 4.9 to 8.7, and this resulted in a 15-fold increase in the dissolved organic carbon concentration (from 4.5 to 69 mg L(-1)). The pH-increase followed the same trend as the release of DOM in the experiment, causing higher DOM solubility and desorption of DOM from mineral sites. The binding to biochar of several well-characterised reference DOM materials was also investigated and results showed a higher sorption of aliphatic DOM to biochar than aromatic DOM, with DOM-water partitioning coefficients (Kd-values) ranging from 0.2 to 590 L kg(-1). A size exclusion occurring in biochar's micropores, could result in a higher sorption of smaller aliphatic DOM molecules than larger aromatic ones. These findings indicate that biochar could increase the leaching of DOM from soil, as well as change the DOM composition towards molecules with a larger size and higher aromaticity.
生物炭是生物质热解的产物，其改良剂已被证明可以通过提高土壤的 pH 值、阳离子交换容量和持水能力等特性来提高酸性土壤的肥力。这些参数在土壤中所含天然有机质的背景下很重要，其中溶解有机质 (DOM) 是可移动和最具生物可利用性的部分。生物炭对土壤中 DOM 的含量和组成的影响尚未得到太多研究关注。本研究重点研究了两种不同生物炭改良剂对酸性旱地土壤和 pH 中性棕色土壤的影响。批处理实验表明，将生物炭以 10wt.%的剂量与旱地土壤混合可将 pH 值从 4.9 提高到 8.7，这导致溶解有机碳浓度增加了 15 倍（从 4.5 增加到 69mgL(-1)）。pH 值的增加与实验中 DOM 的释放趋势相同，导致 DOM 的溶解度更高，从矿物位点解吸 DOM。还研究了几种特征明确的参考 DOM 材料与生物炭的结合情况，结果表明，与芳香族 DOM 相比，生物炭对脂肪族 DOM 的吸附性更高，DOM-水分配系数（Kd 值）范围为 0.2-590Lkg(-1)。生物炭微孔中发生的尺寸排阻作用可能导致较小的脂肪族 DOM 分子比较大的芳香族 DOM 分子具有更高的吸附性。这些发现表明，生物炭可能会增加 DOM 从土壤中的淋溶，以及改变 DOM 的组成，使分子的尺寸更大、芳香性更高。
