纳米银与石墨烯对土壤微生物及土壤酶的影响

采用室内暗培养试验分别探究了纳米银与石墨烯对土壤微生物及土壤酶的不同影响.将不同剂量的纳米银(0、10、100、150 mg·kg~(-1))与高纯石墨烯(0、10、100、1000 mg·kg~(-1))分别与等量棕壤充分混匀,然后进行暗培养.在第3、7、15、30和60 d时取样,测定土壤脲酶、土壤碱性磷酸酶、土壤脱氢酶和土壤过氧化氢酶的活性及土壤细菌、真菌和放线菌的数量,并在培养期间测定土壤呼吸速率及CO2累积量.结果表明,所有纳米银处理均抑制土壤的呼吸作用,并且剂量越高,抑制作用越明显;而石墨烯处理未对土壤呼吸产生显著影响.10 mg·kg~(-1)纳米银处理下,土壤真菌数量在整个培养期内均显著低于对照,土壤细菌在第60 d时也被显著抑制,但土壤放线菌数量无变化;与对照相比,100和150 mg·kg~(-1)的纳米银处理显著降低了土壤细菌、真菌、放线菌的数量.10和100 mg·kg~(-1)的石墨烯处理下,土壤细菌、真菌、放线菌数量则均无显著变化.1000 mg·kg~(-1)的石墨烯显著增加了土壤中细菌与真菌的数量,却对土壤放线菌数量无影响.纳米银处理显著抑制土壤脲酶、脱氢酶活性,却对土壤过氧化氢酶与磷酸酶活性基本无影响.10和100 mg·kg~(-1)石墨烯处理对土壤脲酶有一定的促进作用,1000 mg·kg~(-1)石墨烯处理对土壤过氧化氢酶和脱氢酶有一定的促进作用,而不同剂量的石墨烯在培养后期均对碱性磷酸酶产生抑制作用.总体来说,纳米银在一定程度上对土壤酶及土壤微生物结构产生了负面影响,而石墨烯对土壤酶及土壤微生物结构的影响不明显.

Effect of silver nanoparticles and graphene on soil microorganisms and enzyme activities

The influence of silver nanoparticles (AgNPs) and graphene on soil microbes has drawn more and more attention now. In this work, an incubation experiment was conducted to investigate the effect of AgNPs (0, 10, 100, 150 mg·kg^-1 soil) and graphene (0, 10, 100, 1000 mg·kg^-1 soil) on soil microorganisms and enzyme activities. Soil respiration and accumulation amount of CO₂ were measured throughout the incubation period. Meanwhile, the microbial numbers (bacteria, fungi and actinomycetes) and the enzyme activities (urease, alkaline phosphatase, catalase and dehydrogenase) in soil were evaluated at 3^rd, 7^th, 15^th, 30^th and 60^th day. The results showed that the soil respiration was significantly inhibited only by AgNPs, and the different degree of inhibition depends on the concentration of AgNPs. In comparison to control treatment, the amounts of soil fungi and bacteria were inhibited by 10 mg·kg^-1AgNPs in different degree. When the AgNPs concentration was over 100 mg·kg^-1 in soil, all the soil microbial numbers were significantly decreased. However, the graphene had no significant impact on the number of soil microorganisms at low concentration (<100 mg·kg^-1 soil), but could stimulate the soil bacteria and fungi at high concentration (1000 mg·kg^-1 soil). Further investigation showed that the AgNPs pronouncedly inhibited the soil urease and dehydrogenase activities, but had no effect on soil catalase and alkaline phosphatase activities. However, the graphene had different effects on these soil enzymes compared to that of AgNPs. It promoted the soil urease, catalase and dehydrogenase activities. Instead, the soil alkaline phosphatase activity was inhibited by graphene at the later incubation stage. Findings from this work indicated that the AgNPs had a negative influence on the soil enzymes and microbial structure to some extent, but the graphene had little effect on them.