• 关键词：二氧化钛  沼泽  氮矿化  酶活性

• 基金项目：国家自然科学基金项目（41563008）；云南省高原湿地科学创新团队（2012HC007）

• 范峰华
• 1. 西南林业大学湿地学院, 昆明 650224;2. 国家高原湿地研究中心, 昆明 650224

• 郑荣波
• 西南林业大学化学工程学院, 昆明 650224

• 郭雪莲
• 1. 西南林业大学湿地学院, 昆明 650224;2. 国家高原湿地研究中心, 昆明 650224

• 方昕
• 1. 西南林业大学湿地学院, 昆明 650224;2. 国家高原湿地研究中心, 昆明 650224

• 付倩
• 1. 西南林业大学湿地学院, 昆明 650224;2. 国家高原湿地研究中心, 昆明 650224

• 刘爽
• 1. 西南林业大学湿地学院, 昆明 650224;2. 国家高原湿地研究中心, 昆明 650224

• 摘要：二氧化钛纳米颗粒（TiO₂NPs）的广泛应用使其环境释放量不断增加，从而影响到土壤氮的转化过程.然而，目前关于TiO₂NPs对湖滨沼泽土壤氮矿化的影响机制尚不明确.因此，本研究以典型沼泽土壤为研究对象，通过室内培养实验研究不同剂量TiO₂NPs处理（0 mg·kg^-1（CK）、10 mg·kg^-1（A10）、100 mg·kg^-1（A100）、250 mg·kg^-1（A250）、1000 mg·kg^-1（A1000））对土壤理化性质、酶活性和氮矿化过程的影响，探讨TiO₂NPs输入对土壤氮矿化过程影响的内在机制.结果表明：①不同剂量TiO₂NPs处理显著降低了土壤pH和总有机碳（TOC）含量（p<0.05），A100、A250和A1000处理显著降低了硝态氮（NO₃^--N）含量（p<0.05）.②A250和A1000处理显著抑制了过氧化氢酶活性（p<0.05）；培养7 d，不同剂量TiO₂NPs处理均显著促进了脲酶活性（p<0.05），抑制了脱氢酶活性（p<0.05）；随着培养时间延长，TiO₂NPs处理对脲酶和脱氢酶活性的抑制作用逐渐减弱，表明TiO₂NPs的负面作用会随时间减弱.③不同剂量TiO₂NPs处理对氨化速率没有显著影响（p>0.05），A250、A1000处理对硝化和矿化速率有显著抑制作用（p<0.01）.④土壤氮矿化速率与土壤pH、总磷（TP）、NO₃^--N含量呈显著正相关，与脲酶、过氧化氢酶活性呈显著负相关.TiO₂NPs主要通过改变沼泽土壤NO₃^--N含量影响氮矿化过程.本研究可为湖滨湿地保护和TiO₂NPs环境风险评估提供理论依据.

• Abstract：The wide spread use of TiO₂ nanoparticles (TiO₂NPs) is increasing their environmental release, which could change the process of soil nitrogen transformation. However, the mechanism of the effect of TiO₂NPs input on the mineralization of soil nitrogen in lakeshore marshes is still unclear. In order to explore the effects and the mechanism of TiO₂NPs input on soil nitrogen mineralization, the soil was collected from a lakeshore marsh field and an indoor cultivated experiment with different addition of TiO₂NPs was conducted. The amount of TiO₂NPs was added with 0 mg·kg^-1(CK), 10 mg·kg^-1(A10), 100 mg·kg^-1(A100), 250 mg·kg^-1(A250) and 1000 mg·kg^-1 (A1000), respectively. The soil physiochemical properties, enzyme activities and nitrogen mineralization rate of marsh soil were tested for each treatment. The results showed that ① all TiO₂NPs addition significantly reduced soil pH and total organic carbon (TOC) (p<0.05). The treatments of A100, A250 and A1000 significantly reduced the content of soil nitrate (NO₃^--N) (p<0.05). ② The treatments of A250 and A1000 significantly reduced the activity of catalase (p<0.05). All TiO₂NPs addition significantly promoted the activity of urease, but reduced the activity of dehydrogenase after seven days cultivation. With the prolonged period of cultivation, the inhibition of TiO₂NPs on the activity of urease and dehydrogenase decreased gradually, which means that the negative effect of TiO₂NPs on enzyme activity would fade with time. ③ Treatments with TiO₂NPs addition did not significantly affect soil ammonization rate (p>0.05), while the treatments of A250 and A1000 significantly reduced soil nitrification rate and mineralization rate (p<0.01). ④ Soil nitrogen mineralization rate positively correlated with soil pH, total phosphorus (TP) and NO₃^--N contents, but negatively correlated with the activity of catalase and urease. TiO₂NPs addition changed the mineralization process of soil nitrogen by regulating the content of NO₃^--N in lakeshore marshes. This study provides a theoretical basis for the protection of lakeshore marshes and the assessment of TiO₂NPs environmental risks.

• Key words：TiO₂ nanoparticles  marsh soil  nitrogen mineralization  enzyme activity

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