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| Response of methane emission and the related microbial abundance to sulfamethazine and copper in paddy soils |
| Received:February 23, 2021 |
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| KeyWord:copper (Cu);sulfamethazine (SMZ);pig manure;paddy field;CH4 emissions;functional gene |
| Author Name | Affiliation | E-mail | | CHENG Suyu | College of Resource and Environmental Sciences, Nanjing Agricultural University, Nanjing 210095, China | | | ZHU Changjun | College of Resource and Environmental Sciences, Nanjing Agricultural University, Nanjing 210095, China | | | LI Xinyu | College of Resource and Environmental Sciences, Nanjing Agricultural University, Nanjing 210095, China | | | DONG Ning | College of Resource and Environmental Sciences, Nanjing Agricultural University, Nanjing 210095, China | | | ZHOU Jinrong | College of Resource and Environmental Sciences, Nanjing Agricultural University, Nanjing 210095, China | | | JIANG Jingyan | College of Resource and Environmental Sciences, Nanjing Agricultural University, Nanjing 210095, China | lilacjjy@njau.edu.cn |
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| Abstract: |
| The production of greenhouse gases, such as methane is of increasing concern with respect to climate change. Methanogenesis has been tied to certain functional genes in the microorganisms that produce methane through anaerobic processes(methanogens). This study investigated the impacts of the singly or combined pollution of sulfamethazine(SMZ) and copper(Cu) upon the relative abundance of functional genes of methanogens in livestock manure and their resultant methane production. A long-term incubation experiment was simulated using manure as a source of fertilizer on flooded soils. Selected concentrations of SMZ(0, 0.1, 1 mg·kg-1, and 5 mg·kg-1) and Cu (0, 100, 500 mg·kg-1, and 1 500 mg·kg-1) were added to the soil-manure mixture in paired combinations. The study incorporated sixteen treatments, including a control(Cu0+SMZ0), and fifteen different paired concentrations levels of Cu and SMZ treatments(Cu0+SMZ0.1, Cu0+SMZ1, Cu0+SMZ5, Cu100+SMZ0, Cu100+SMZ0.1, Cu100+SMZ1, Cu100+SMZ5, Cu500+SMZ0, Cu500+SMZ0.1, Cu500+SMZ1, Cu500+SMZ5, Cu1500+SMZ0, Cu1500+SMZ0.1, Cu1500+SMZ1 and Cu1500+SMZ5). CH4 emission rates and related microorganism functional gene abundance were tested at regular intervals of incubation and analyzed for exploring the dose and tolerance effects of single and combined treatments of SMZ and Cu on CH4 emissions and the related microorganism gene abundance. Study results showed that during the early stages of incubation(0~12 d), different concentration treatments of SMZ and Cu had no significant effect on CH4 emission (P>0.05). In the middle and late stages of incubation(13~71 d), the addition of a low concentration of only SMZ(Cu0+SMZ0.1) in the soil promoted CH4 emissions, while a high concentration of SMZ(≥ 1 mg·kg-1) had an inhibitory effect. Both single treatments of high-moderate concentrations of Cu and combined treatments of Cu and SMZ significantly reduced the CH4 emission rate(P<0.05). In comparison with the control, the Cu0 + SMZ0.1 treatment increased cumulative CH4 emissions by 19.7%. All other treatments significantly reduced CH4 emissions(P<0.05), specifically the combined treatments of Cu and SMZ, which decreased CH4 emissions by approximately 77%. Single treatment by SMZ had dose- and time-dependent effects on the abundance of the 16S rRNA-CH4, mcrA, and pmoA genes. However, single treatments of Cu had no dose-or time-dependent effects. Moreover, results of the interaction between SMZ and Cu were complex, and primarily dependent upon the initial dose and application duration of SMZ. In the middle and late stage, application of middle or high concentrations of Cu, either singly or combined with SMZ at concentrations ≥ 1 mg·kg-1, significantly reduced the relative abundance of the above-mentioned genes(P<0.05). Abundance of the pmoA gene was more sensitive to the single and combined treatments by Cu and SMZ than the 16S rRNA-CH4 and mcrA genes. The joint application of sulfamethazine and copper can reduce CH4 emissions and the relative abundance of the microorganism genes in paddy soil. This is beneficial to greenhouse gas emission mitigation. However, the environmental risk of high concentrations of residual antibiotics and heavy metals in livestock and poultry manure should not be ignored. |
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