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| Effect of sulfadiazine on soil respiration and enzyme activity under copper stress |
| Received:January 11, 2019 |
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| KeyWord:sulfadiazine;Cu;soil enzyme activity;soil respiration |
| Author Name | Affiliation | E-mail | | LI Ming-zhu | School of Agricultural Engineering and Food Science, Shandong University of Technology, Zibo 255091, China | | | LIAO Qiang | School of Agricultural Engineering and Food Science, Shandong University of Technology, Zibo 255091, China | | | DONG Yuan-peng | School of Agricultural Engineering and Food Science, Shandong University of Technology, Zibo 255091, China | | | LIU Xi-juan | School of Agricultural Engineering and Food Science, Shandong University of Technology, Zibo 255091, China | | | MENG Zi-lin | School of Resources and Environment Engineering, Shandong University of Technology, Zibo 255091, China | | | LI Meng-hong | School of Resources and Environment Engineering, Shandong University of Technology, Zibo 255091, China | | | LIU Ai-ju | School of Resources and Environment Engineering, Shandong University of Technology, Zibo 255091, China | aijvliu@sdut.edu.cn |
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| Abstract: |
| In this study, sulfadiazine (SDZ)and copper (Cu)were chosen as typical pollutants to investigate their combined effects on soil microbial respiration and soil enzyme activities. The following six soil contamination treatments were established:SDZ5 (5 mg·kg-1), SDZ10 (10 mg·kg-1), SDZ5+Cu200 (5 mg·kg-1 SDZ and 200 mg·kg-1 Cu), SDZ5+Cu500 (5 mg·kg-1 SDZ and 500 mg·kg-1 Cu), SDZ10+Cu200 (10 mg·kg-1 SDZ and 200 mg·kg-1 Cu), and SDZ10+Cu500 (10 mg·kg-1 SDZ and 500 mg·kg-1 Cu). SDZ significantly promoted soil respiration at 7 days of incubation, and copper co-addition significantly strengthened this effect, which, however, gradually weakened and returned to the control level at the 28th day of incubation. Moreover, throughout the incubation period, soil dehydrogenase activity was strongly (P<0.05)inhibited by all of the contamination treatments, including SDZ single amendments and co-addition of Cu. Soil phosphatase activity showed a certain degree of tolerance and hysteresis to SDZ pollution, as there was no significant effect of 5 mg·kg-1 SDZ on soil phosphatase activity, and 10 mg·kg-1 SDZ induced significant inhibition only after 14~28 days of incubation; however, the combined pollution of SDZ and Cu resulted in significant (P<0.05)inhibition on soil phosphatase throughout the experiments. In contrast to dehydrogenase and phosphatase, urease activity was not significantly influenced by the treatments SDZ5 and SDZ5+Cu200, and only inhibited by treatment with SDZ10 on the 7th day of incubation and by treatment with SDZ along with 500 mg·kg-1 Cu at the 7th, 14th, and 28th day of incubation. Addition of 5 mg·kg-1 SDZ significantly stimulated β-G-glucosidase activity, which was greatly inhibited by treatment with SDZ and 500 mg·kg-1 Cu. Therefore, it could be concluded that the response of soil respiration to SDZ and its co-pollution with Cu was closely related to the concentration of the pollutants and exposure time. Further, soil enzymes showed different responses to SDZ and its co-pollution with Cu, which were greatly affected by the amounts of the pollutants. In contrast, dehydrogenase was more sensitive to SDZ single and Cu + SDZ combined pollution, which could be used as an indicator to evaluate these types of contaminants. However, soil phosphatase and β-Gglucosidase were only sensitive to the combined pollution with SDZ and heavy metals. |
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