Institute of Coastal Environmental Pollution Control, Key Laboratory of Marine Environmental Science and Ecology, Ministry of Education, College of Environmental Science and Engineering, Ocean University of China, Qingdao 266100, China.
College of Environmental Science and Engineering, Qingdao University, Qingdao 266071, China.
Sci Total Environ. 2017 Dec 31;607-608:1428-1436. doi: 10.1016/j.scitotenv.2017.07.046. Epub 2017 Jul 21.
The aging of biochar by low molecular weight organic acids (LMWOAs), which are typical root-derived exudates, is not well understood. Three LMWOAs (ethanoic, malic, and citric acids) were employed to investigate their aging impacts on the biochars from furfural production residues at 300-600°C (BC300-600). The LMWOAs created abundant macropores in BC300, whereas they significantly increased the mesoporosity and surface area of BC600 by 13.5-27.0% and 44.6-61.5%, respectively. After LMWOA aging, the content of C and H of the biochars increased from 51.3-60.2% and 1.87-3.45% to 56.8-69.9% and 2.06-4.45%, respectively, but the O content decreased from 13.8-24.8% to 7.82-19.4% (except BC300). For carbon fraction in the biochars, the LMWOAs barely altered the bulk and surface functional properties during short-term aging. The LMWOAs facilitated the dissolution of minerals (e.g., KMg(PO), AlPO, and PbPO) and correspondingly promoted the release of not only plant nutrients (K, Ca, Mg, Fe, PO, and SO) but also toxic metals (Al and Pb). This research provided systematic insights on the responses of biochar properties to LMWOAs and presented direct evidence for acid activation of inorganic minerals in the biochars by LMWOAs, which could enhance the understanding of environmental behaviors of biochars in rhizosphere soils.
低分子量有机酸（LMWOAs）对生物炭的老化作用（LMWOAs 是典型的根系分泌物）尚未得到很好的理解。本研究采用三种 LMWOAs（乙酸、苹果酸和柠檬酸）来研究它们对糠醛生产残渣在 300-600°C（BC300-600）下生成的生物炭老化的影响。LMWOAs 在 BC300 中产生了丰富的大孔，而它们分别使 BC600 的中孔和比表面积显著增加了 13.5-27.0%和 44.6-61.5%。LMWOA 老化后，生物炭中 C 和 H 的含量分别从 51.3-60.2%和 1.87-3.45%增加到 56.8-69.9%和 2.06-4.45%，而 O 的含量则从 13.8-24.8%下降到 7.82-19.4%（BC300 除外）。对于生物炭中的碳组分，LMWOAs 在短期老化过程中几乎没有改变其整体和表面官能团特性。LMWOAs 促进了矿物质（如 KMg(PO)、AlPO 和 PbPO）的溶解，相应地促进了不仅植物营养元素（K、Ca、Mg、Fe、PO 和 SO）而且有毒金属（Al 和 Pb）的释放。这项研究提供了系统的认识生物炭性质对 LMWOAs 的响应，并为 LMWOAs 对生物炭中无机矿物质的酸活化提供了直接证据，这可以增强对生物炭在根际土壤中环境行为的理解。
