| Abstrakt: |
Purpose: As a common conservation tillage technology, crop straw returning could not only increase soil nutrients and improve soil structure, but also has been utilized for remedying PAHs-contaminated upland soil. However, the influence and the related mechanisms of wheat straw on the removal of PAHs in paddy soil are still unclear. Materials and methods: An incubation experiment used wheat straw (20 g kg−1, S), middle (200 mg kg−1) and/or high (800 mg kg−1) level of urea-N (N1 and N2), and 3, 4-dimethylpyrazole phosphate (80 mg kg−1, DMPP) was conducted to investigate the effects of wheat straw on phenanthrene (PHE) degradation in paddy soil. Dissolved organic carbon (DOC), NO3−, NH4+, denitrification activity (DEA), hydroxylamine reductase (Hyr), bacterial community, and function genes were determined to investigate the mechanisms of PHE degradation. Results: PHE concentration in paddy soil was significantly (p < 0.05) decreased by 4-40%, but DOC concentration was significantly (p < 0.05) increased under S, SN1, SN2, SD, SN1D, and SN2D after 63 days of incubation. DOC was positively (p < 0.01) associated with PHE concentration in drowned water, indicating that DOC increased PHE bioavailability in paddy soil. S, SN1, and SN2 increased NO3− concentration, and the activity of DEA and Hyr, which was positively (p < 0.01) associated with the removal rate of PHE. Wheat straw significantly changed the bacterial community and increased the abundance of PHE degrader (Ruminiclostridium, Christensenellaceae_R-7_group, Christensenellaceae_unclassified, and Bacteroidetes_vadinHA17_unclassified) and PHE biodegradation function genes (norB, nosZ, nrfA, and bamA). DMPP increased the abundance of PHE degraders and PHE degradation genes. Conclusions: Wheat straw application enhanced PHE biodegradation in paddy soil via promoting NO3− reduction as well as increasing PHE bioavailability and the abundance of PHE degraders and PHE degradation genes. The present results provided a new strategy for PAHs removal in paddy soil, guaranteeing agricultural production safety. [ABSTRACT FROM AUTHOR] |
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