不同培养介质中纳米氧化铜对小麦毒性的影响（Influence of Culture Media on the Phytotoxicity of CuO Nanoparticles to Wheat（Triticum aestivum L.））

通过比较纳米氧化铜(CuONPs)和微米氧化铜(CuOMPs)在两种土壤中Cu2+的溶出及其对脲酶活性影响,结合产生脲酶活性抑制效应的Cu2+浓度阈值,研究了CuONPs和CuOMPs对土壤脲酶活性的毒性效应机制.结果表明:CuONPs和CuOMPs的Cu2+溶出量随其浓度增加而增加,溶出比率随浓度增加而减少,两者在红壤中Cu2+的溶出均比在乌栅土中高;在1～1000mg·kg-1范围内,CuONPs对土壤脲酶活性产生了显著(p≤0.05)或极显著(p≤0.01)的抑制效应;同浓度下,CuONPs在土壤中的Cu2+溶出及其对脲酶活性的抑制效应均大于CuOMPs;在相对低浓度(1～10mg·kg-1,红壤;1～100mg·kg-1,乌栅土)下,CuO的纳米态对土壤脲酶活性具有抑制毒性,在相对高浓度(≥50mg·kg-1,红壤;≥500mg·kg-1,乌栅土)下,CuO的纳米态和溶出Cu2+共同作用引起了脲酶活性抑制;与CuONPs不同,CuOMPs只有通过溶出Cu2+抑制土壤脲酶活性,其颗粒态对脲酶活性无显著影响;值得注意的是,在低浓度(1mg·kg-1)下CuONPs对土壤脲酶活性具有微米态和离子态所没有的抑制毒性,说明其对土壤酶影响应存在特殊机理,值得进一步深入研究.

Comparative Ecotoxicity of Nanometer-, Micrometer-Sized CuO and Ionic Copper to Soil Urease

To explore the ecotoxicology of nanometer-and micrometer-sized CuO to soil urease activity,the release of Cu2+ from CuO and their effects on inhibiting urease activity have been investigated.The results show that the release of Cu2+ from CuO nanoparticles(CuO NPs) and CuO micrometer-sized particles(CuO MPs)increased with increasing particle concentrations,while the releasing ratio to CuO was decreased.Both of Cu2+ release and its ratio to CuO was higher in Red soil(RS,Udic Ferrosols) than that in Wushan soil(WS,Anthrosol).In the concentration range of 1~1000mg CuO NPs·L-1(calculated by Cu concentration),soil urease activity was significantly(p≤0.05 and p≤0.01) inhibited by CuO NPs.In addition,both of Cu2+ release and inhibition of urease activity induced by CuO NPs were greater than those by CuO MPs with the same concentration.When the concentration of CuO NPs was relatively low(1~10mg·kg-1 in RS and 1~100mg·kg-1 in WS),the nanoparticulate determined the ecotoxicity on urease activity.Whereas,the combined effects of released Cu2+ and nanoparticulate were dominated the inhibition of urease activity when the concentration of CuO NPs was relatively high(≥50mg·kg-1 in RS,≥500mg·kg-1 in WS).It was different from CuO NPs that the inhibition of urease activity caused by CuO MPs only through the release of Cu2+.It should be noted that 1mg·kg-1 CuO NPs significantly(p≤0.05)inhibited urease activity,while the effects of CuO MPs and Cu2+ showed nothing there.It indicates that there would be unique mechanism for the effects of nanoparticulate CuO on soil enzyme,and further work is required to be done to clarify details.