Institute of Geographic Sciences and Natural Resources Research, Chinese Academy of Sciences, Beijing, 100101, China.
Northeast Institute of Geography and Agroecology, Chinese Academy of Sciences, Changchun, 130102, China.
J Environ Manage. 2022 Mar 1;305:114387. doi: 10.1016/j.jenvman.2021.114387. Epub 2021 Dec 27.
Composting is suitable for recycling livestock manure into valuable organic fertilizer, which can improve soil quality while mitigating potential risk of heavy metal pollution. Humic substances (HS) in compost have been demonstrated to play a key role in regulating the redistribution of heavy metal fractions. However, limited direct information have been reported on how different components of HS complexes with heavy metals to affect their bioavailability during composting. In this study, sequential extraction procedures (HO, KCl, NaPO, NaOH and HNO) were used to assess the characteristics that HS bound with Cu and Zn during composting of swine manure and straw added either 5% boron waste (BW) or 5% phosphate rock (PR). Organically complexed fraction extracted by NaPO contained only 33-41% of the Cu but most of the Zn (81-87%). During composting, initially mobile fractions of Cu and Zn (extracted by HO or KCl) changed into more stable fractions (extracted by NaOH and HNO), and both organic matter and fulvic acids (FA) were identified as critical factors to explain this redistribution based on redundancy analysis. Over 80% of Cu and Zn were complexed with FA of HS. However, exogenous additives (phosphate rock and boron waste) enhanced Cu conversion by promoting humification (Humic acid/Fulvic acids, HA/FA) whereas they had limited influence on Zn, due to the relatively weak binding relationship between Zn and HA.
堆肥适合将牲畜粪便回收为有价值的有机肥料，既能提高土壤质量，又能降低重金属污染的潜在风险。堆肥中的腐殖质（HS）已被证明在调节重金属形态的再分配方面起着关键作用。然而，关于 HS 复合物如何与重金属结合影响其在堆肥过程中的生物有效性的直接信息有限。在这项研究中，采用连续提取程序（HO、KCl、NaPO、NaOH 和 HNO）来评估在添加 5%硼废物（BW）或 5%磷矿（PR）的猪粪和秸秆堆肥过程中 HS 与 Cu 和 Zn 结合的特征。通过 NaPO 提取的有机络合部分仅含有 33-41%的 Cu，但含有大部分 Zn（81-87%）。在堆肥过程中，Cu 和 Zn 的初始可移动部分（通过 HO 或 KCl 提取）转变为更稳定的部分（通过 NaOH 和 HNO 提取），基于冗余分析，确定有机质和富里酸（FA）是解释这种重分配的关键因素。超过 80%的 Cu 和 Zn 与 HS 的 FA 结合。然而，外源性添加剂（磷矿和硼废物）通过促进腐殖化（腐殖酸/富里酸，HA/FA）促进了 Cu 的转化，而对 Zn 的影响有限，因为 Zn 与 HA 的结合关系较弱。
