不同价态金属阳离子对椴木屑腐解期间腐殖质组成的动态影响

Dynamic effects of metal cations with different valences on humus composition during decomposition of basswood chips

【目的】研究不同价态金属阳离子对天然富含木质素的椴木屑在腐解期间腐殖质组成的影响,明确各金属阳离子对椴木屑腐殖化进程的贡献,为以木质素为主要成分的农业固体废弃物的资源化利用提供参考。【方法】采用室内恒温培养法,以富含木质素的椴木屑为供试材料,在培养体系中分别添加0.5 mol/LK^(+)、Mn^(2+)和Fe^(3+),以不添加任何金属阳离子为对照(CK),于28℃恒温好氧培养90 d,分别在培养0,45和90 d时取样,分析椴木屑腐解期间总有机碳(TOC)、水溶性物质碳含量(C_(WSS))、可提取腐殖酸碳含量(CHE)、胡敏酸(HA)碱溶液色调系数(Δlg K)、胡富比(胡敏酸与富里酸碳含量之比,C_(HA)/C_(FA))和胡敏素碳含量(C_(Hu))的变化。【结果】(1)随着培养时间的延长,不同处理的TOC含量均表现为先升高后下降的变化规律;培养结束(90 d)时与CK相比,Mn^(2+)和Fe^(3+)处理的TOC含量均显著下降,其中Mn^(2+)处理的TOC含量下降幅度较大。(2)随着培养时间的延长,各处理C_(WSS)先降低后升高,最终表现为K^(+)和Fe^(3+)能够促进WSS的积累,而Mn^(2+)更易促进WSS的消耗。(3)与其他处理相比,添加Fe^(3+)不仅减缓了CHE的下降,而且在整个培养期间使CHE维持在最高水平。(4)与培养0 d相比,培养结束时,Fe^(3+)和K^(+)处理的HA碱溶液Δlg K均下降,而Mn^(2+)处理的HA碱溶液Δlg K则增加;Fe^(3+)和Mn^(2+)处理的C_(HA)/C_(FA)分别降低了13.1%和6.7%,K^(+)处理的C_(HA)/C_(FA)无显著变化;Fe^(3+)、Mn^(2+)、K^(+)和CK处理的C_(Hu)分别下降了37.9%,14.6%,11.2%和21.5%,其中Fe^(3+)更有利于促进Hu的矿化分解。【结论】相比于K^(+)和Mn^(2+),Fe^(3+)可有效促进椴木屑的分解并释放WSS,在促进Hu矿化的同时还能减缓HE的下降。

【Objective】The effect of metal cations with different valences on humus composition of na-tural lignin-rich basswood chips during decomposing was studied and the contribution of metal cation to humification process was clarified to provide reference for resource utilization of agricultural solid wastes with lignin as the main component.【Method】The indoor constant temperature culture method was adopted for lignin-rich basswood chips with 0.5 mol/L K^(+),Mn^(2+)and Fe^(3+),respectively.The case without metal cation was used as the control(CK).The test was at a constant temperature of 28℃for 90 d,and the samples were taken on days 0,45 and 90.The changes in total organic carbon(TOC),carbon content of water-soluble substances(C_(WSS)),humic-extracted acid(CHE),Δlg K value of humic acid(HA)alkaline solution,Hufu ratio(ratio of carbon content of humic acid to fulvic acid,C_(HA)/C_(FA))and humin(C_(Hu))during degradation were analyzed.【Result】(1)TOC contents of different treatments increased first and then decreased.At the end of culture(90 d),TOC contents of Mn^(2+)and Fe^(3+)treatments decreased significantly compared with CK,and TOC content of Mn^(2+)treatment decreased more.(2)With the extension of culture time,C_(WSS)of each treatment decreased at first and then increased.K^(+)and Fe^(3+)promoted WSS accumulation,while Mn^(2+)promoted WSS consumption.(3)Compared with other treatments,Fe^(3+)addition not only slowed the decline of CHE,but also maintained CHEat the highest level during the whole culture period.(4)Compared with 0 d,Δlg K value of HA alkaline solution treated with Fe^(3+)and K^(+)decreased at the end of culture,while that with Mn^(2+)increased.The C_(HA)/C_(FA)ratio of Fe^(3+)and Mn^(2+)treatments decreased by 13.1%and 6.7%,respectively,while that of K^(+)treatment had no significant change.C_(Hu)treated by Fe^(3+),Mn^(2+),K^(+)and CK decreased by 37.9%,14.6%,11.2%and 21.5%,respectively,and Fe^(3+)was more conducive to mineralization and decomposition of humin(Hu).【Conclusion】Compared with K^(+)and Mn^(2+),Fe^(3+)was better in effectively promoting decomposition of basswood chips and release of water-soluble substances(WSS),which slowed down the decline of humic-extracted acid(HE)and promoted the mineralization of Hu.