Soil Fertility And Microbial Community Structure In Soil Contaminated By Nano Silver

With the rapid development of nanotechnology,nanomaterials inevitably enter the soil environment and accumulate.Therefore,it is significance to research on nanomaterial to the soil environment security and agricultural products.So the effects of nano silver on soil fertilizer and microbial community structure were studied In this paper.The effects of different concentrations of nano silver on soil microbial community structure were analyzed by high throughput sequencing.And the analysis of the soil fertilizer was mainly through the investigation of the effects of nano silver on soil nitrogen and phosphorus content,soil enzyme activity,soil dissolved organic matter(DOM)under the condition of the drought and flooding.The main results were as follows:1.The effects of nano silver on the content of N in soil showed that the content of nitrate nitrogen and nitrite nitrogen in soil decreased with the increase of the concentration of nano silver under the condition of the drought.When the concentration of nano silver was 100 mg/kg,the content of nitrate in soil decreased significantly in the 30 d and 60 d treatment.Under the condition of the flooding,the content of nitrate nitrogen in soil decreased with the increase of the concentration of nano silver in the 30 d treatment.But the content of nitrate nitrogen increased with the increase of the concentration of nano silver in the 60 d treatment.And the content of nitrite nitrogen in soil decreased with the increase of the concentration of nano silver in the 30 d and 60 d treatment.But when the concentration of nano silver was 500 mg/kg,the content of soil nitrite increased.2.The effects of nano silver on the content of P in soil showed that the concentration of nano silver at 0 mg/kg-500 mg/kg promoted the transformation of phosphorus release and consumption under the condition of the drought.But with the increase of the concentration of nano silver,the transformation of phosphorus release and consumption was inhibited.The amount of available phosphorus showed an upward trend due to accumulation.And the transformation of phosphorus release and consumption was inhibited at the range of 100 mg/kg-500 mg/kg and 1000 mg/kg-5000 mg/kg of nano silver under the condition of the flooding.while in the range of 0 mg/kg-100 mg/kg and 500mg/kg-1000 mg/kg of nano silver,the transformation of phosphorus release and consumption was promoted.3.The effects of nano silver on soil DOM were analyzed only by made an simple UV spectrum.It showed that the absorbance of the long wave direction was larger under the high concentration of nano silver in soil.The results suggestted that the the content ofconjugated material was higher,and the greater the adsorption of nano silver.In this paper,the absorption coefficient of DOM under the condition of the flooding was significantly lower by comparing with the condition of the drought and flooding.4.The effects of nano silver on enzyme activity in soil showed that the activity of urease and dehydrogenase in soil were inhibited by nano silver under the condition of the drought.But had no significant inhibitory effect on alkaline phosphatase.Under the condition of the flooding,the activity of these three enzymes was inhibited by nano silver.5.The effects of nano silver on soil microbial community structure showed that the dominant bacteria of all soil samples under the condition of the drought were Acidobacteria,Proteobacteria,Bacteroidetes,Planctomycetes,Chloroflexi,Armatimonadetes and Chlorobi.The absolute dominant group in the soil samples of the control group was the Bacteroidetes.And the absolute dominant group in the soil samples of the treatment group was the Proteobacteria.This indicated that nano silver had a certain effect on the Proteobacteria,and had a certain inhibitory effect on the Bacteroidetes.From the proportion of the abundance of microbial species,different concentrations of nano silver had a significant inhibitory effect on Armatimonadetes,Chloroflexi and Chlorobi.And it had a significant effect on Acidobacteria and Actinobacteria.Under the condition of the flooding,the dominant bacteria were Proteobacteria,Chloroflexi,Bacteroidetes,Acidobacteria,Actinobacteria,Firmicutes and Planctomycetes.The absolute dominant group in the soil samples of the control group was the Proteobacteria.And the absolute dominant group in the soil samples of the treatment group was also the Proteobacteria.This indicated that nano silver had no effect on the Proteobacteria.From the proportion of the abundance of microbial species,the species composition of the soils treated with different concentrations of nano silver were similar.Nano silver had no significant effect on the microbial community structurein the experimental concentration range.