Effects of maize straw and root stubble return on degradation and fractions of PAHs in contaminated soils.

Autor: Wu, Xiangyao, Cai, Jun, Zhang, He, Wu, Yunmei, Wang, Jinfeng, Sun, Benhua, Wu, Fuyong
Předmět:
Zdroj: Journal of Soils & Sediments: Protection, Risk Assessment, & Remediation; Jan2024, Vol. 24 Issue 1, p163-176, 14p
Abstrakt: Purpose: Polycyclic aromatic hydrocarbons (PAHs) are universal in agricultural soils, and threaten food security and sustainable agricultural development. Straw return is widely used as soil amendment for promoting sustainable farmland use and remedying pollution of PAHs. However, the effects and related mechanisms of different residual parts of crops on the remediation of PAHs-contaminated soils are still unclear. Materials and methods: In this study, CO2 emissions, concentrations of dissolved organic carbon (DOC) and soil microbial biomass carbon (MBC), concentrations and fractions of PAHs were measured to investigate whether the response of PAHs degradation to maize straw and root stubble addition at four levels (0%, 1%, 2.5%, and 5%, w/w) was different in PAHs-contaminated soils. Partial least squares path modeling (PLS-PM) was utilized to investigate the transformation of four fractions of PAHs (water-soluble, organic acid-soluble, organically bound, and residual PAHs). Results: The present research demonstrated that 5% straw addition (49.05%) significantly (p < 0.05) enhanced PAHs degradation rate compared to 5% root addition (45.60%). The reason for this is that the former significantly (p < 0.05) increased concentrations of DOC (from 6.62 to 11.34%) and MBC (from 7.66 to 23.63%) in soils more than the latter. Based on random forest analysis (a model strength of 99.19%, p < 0.001), DOC, MBC and PAHs fractions were the major contributors to the degradation of PAHs, with their contributions ranging from 14.43 to 30.28%. Furthermore, PLS-PM analysis (a goodness-of-fit of 0.872) revealed that the transformation from lower bioavailable fractions (organically bound and residual PAHs) to more bioavailable fractions (water-soluble and organic acid-soluble PAHs) was the primary factor influencing PAHs degradation. Conclusions: Our findings demonstrated that the efficiency of PAHs degradation under higher ratio of straw addition was significantly higher than that of root stubble in PAHs-contaminated soils, which was due to the transformation of PAHs fractions caused by increasing of DOC and MBC. [ABSTRACT FROM AUTHOR]
Databáze: Complementary Index
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