在微生物的代谢活动下,土壤中有机态碳氮化合物矿化分解释放矿质养分和二氧化碳,深刻影响着自然生态系统土壤碳、氮等元素的循环转化、土壤的养分供应和有机质的更新,并对地上植被的演替和分布有极为重要的意义。青藏高原灌丛面积分布广...在微生物的代谢活动下,土壤中有机态碳氮化合物矿化分解释放矿质养分和二氧化碳,深刻影响着自然生态系统土壤碳、氮等元素的循环转化、土壤的养分供应和有机质的更新,并对地上植被的演替和分布有极为重要的意义。青藏高原灌丛面积分布广泛,地形和气候条件复杂,但目前对灌丛分布地区土壤碳氮含量、矿化作用强度及其影响因素等的认识较少。研究结合土壤理化分析和高通量定量PCR(quantitative microbial element cycling, QMEC)技术研究了青藏高原喜马拉雅山-冈底斯山地区不同类型灌丛土壤碳氮含量、碳氮矿化速率和相关功能基因的分布特征及其与植被、气候和土壤因子间的耦联关系。结果表明,不同类型灌丛土壤的有机碳、全氮含量、CO_(2)释放速率、净氮矿化速率、碳氮矿化基因的丰度有显著差异。其中,位于青藏高原东南部的雪层杜鹃和香柏灌丛分布区土壤有机碳和全氮含量、CO_(2)释放速率、净氮矿化速率显著高于位于中西部的变色锦鸡儿、金露梅和砂生槐灌丛地区,并与年平均降雨量显著正相关。然而,碳、氮矿化基因丰度分布趋势与之相反,在雪层杜鹃和香柏灌丛分布区丰度显著低于中西部的三类灌丛,且与年平均降雨量呈显著负相关,但与土壤pH呈显著正相关。同时pH与年平均降水量、湿润指数和土壤含水率均为显著负相关。这些结果表明降水可通过增加盐基离子淋溶,使土壤盐基饱和度下降、氢饱和度增加,引起土壤酸化,进而影响碳氮循环过程,导致不同类型灌丛土壤碳氮元素的赋存及其周转速率差异。同时,碳、氮矿化相关功能基因丰度各类群间呈现显著的正相关关系,表明土壤碳氮循环过程间紧密的耦联关系。这些结果为准确评估青藏高原土壤碳、氮库及其动态平衡提供了重要信息和参考依据。展开更多
An ultrasensitive electrochemical biosensor was fabricated for electroanalytical determination of ascorbic acid(AA),dopamine(DA)and uric acid(UA)individually and simultaneously based on polypyrrole hollow nanotubes lo...An ultrasensitive electrochemical biosensor was fabricated for electroanalytical determination of ascorbic acid(AA),dopamine(DA)and uric acid(UA)individually and simultaneously based on polypyrrole hollow nanotubes loaded with Au and Fe_(3)O_(4) nanoparticles(NPs)uniformly(PPy@Au-Fe_(3)O_(4)).The PPy@Au-Fe_(3)O_(4) nanotubes were synthesized in one-pot using MoO_(3) nanorods as templates and the polymerization of Py,the formation of Au and Fe_(3)O_(4) NPs and the removel of MoO_(3) templates took place stimultaneously.Electrochemical studies reveal that PPy@Au-Fe_(3)O_(4) modified glassy carbon electrode(GCE)possesses excellent electrocatalytic activities toward the oxidation of AA,DA and UA.Their oxidation peak currents increase linearly in the concentration ranges of 1–2000µmol/L for AA,0.01–25 and 25–300µmol/L for DA and 0.1–300µmol/L for UA.Their detection limit values(S/N=3)were calculated as 0.45,0.0049,and 0.051µmol/L for AA,DA and UA in the individual detection.By changing the concentrations simultaneously,the calibration curves showed linearity to 1000,200,and 200µmol/L with detection limit of 0.39,0.0060,and 0.060µmol/L for AA,DA,and UA,respectively.Finally,the obtained biosensor was successfully applied to the detection of AA,DA,and UA with satisfactory results on actual samples.展开更多
文摘在微生物的代谢活动下,土壤中有机态碳氮化合物矿化分解释放矿质养分和二氧化碳,深刻影响着自然生态系统土壤碳、氮等元素的循环转化、土壤的养分供应和有机质的更新,并对地上植被的演替和分布有极为重要的意义。青藏高原灌丛面积分布广泛,地形和气候条件复杂,但目前对灌丛分布地区土壤碳氮含量、矿化作用强度及其影响因素等的认识较少。研究结合土壤理化分析和高通量定量PCR(quantitative microbial element cycling, QMEC)技术研究了青藏高原喜马拉雅山-冈底斯山地区不同类型灌丛土壤碳氮含量、碳氮矿化速率和相关功能基因的分布特征及其与植被、气候和土壤因子间的耦联关系。结果表明,不同类型灌丛土壤的有机碳、全氮含量、CO_(2)释放速率、净氮矿化速率、碳氮矿化基因的丰度有显著差异。其中,位于青藏高原东南部的雪层杜鹃和香柏灌丛分布区土壤有机碳和全氮含量、CO_(2)释放速率、净氮矿化速率显著高于位于中西部的变色锦鸡儿、金露梅和砂生槐灌丛地区,并与年平均降雨量显著正相关。然而,碳、氮矿化基因丰度分布趋势与之相反,在雪层杜鹃和香柏灌丛分布区丰度显著低于中西部的三类灌丛,且与年平均降雨量呈显著负相关,但与土壤pH呈显著正相关。同时pH与年平均降水量、湿润指数和土壤含水率均为显著负相关。这些结果表明降水可通过增加盐基离子淋溶,使土壤盐基饱和度下降、氢饱和度增加,引起土壤酸化,进而影响碳氮循环过程,导致不同类型灌丛土壤碳氮元素的赋存及其周转速率差异。同时,碳、氮矿化相关功能基因丰度各类群间呈现显著的正相关关系,表明土壤碳氮循环过程间紧密的耦联关系。这些结果为准确评估青藏高原土壤碳、氮库及其动态平衡提供了重要信息和参考依据。
基金supported by the National Natural Science Foundation of China(Nos.22004028,21722501,21803018)the Henan Special Support for High-Level Talents Central Plains Science and Technology Innovation Leading Talents of China(No.204200510006)+1 种基金the Key Project of Science and Technology of Henan Province,China(Nos.202102310139,2121102311071)the Natural Science Foundation of Henan Province,China(No.222300420207).
文摘An ultrasensitive electrochemical biosensor was fabricated for electroanalytical determination of ascorbic acid(AA),dopamine(DA)and uric acid(UA)individually and simultaneously based on polypyrrole hollow nanotubes loaded with Au and Fe_(3)O_(4) nanoparticles(NPs)uniformly(PPy@Au-Fe_(3)O_(4)).The PPy@Au-Fe_(3)O_(4) nanotubes were synthesized in one-pot using MoO_(3) nanorods as templates and the polymerization of Py,the formation of Au and Fe_(3)O_(4) NPs and the removel of MoO_(3) templates took place stimultaneously.Electrochemical studies reveal that PPy@Au-Fe_(3)O_(4) modified glassy carbon electrode(GCE)possesses excellent electrocatalytic activities toward the oxidation of AA,DA and UA.Their oxidation peak currents increase linearly in the concentration ranges of 1–2000µmol/L for AA,0.01–25 and 25–300µmol/L for DA and 0.1–300µmol/L for UA.Their detection limit values(S/N=3)were calculated as 0.45,0.0049,and 0.051µmol/L for AA,DA and UA in the individual detection.By changing the concentrations simultaneously,the calibration curves showed linearity to 1000,200,and 200µmol/L with detection limit of 0.39,0.0060,and 0.060µmol/L for AA,DA,and UA,respectively.Finally,the obtained biosensor was successfully applied to the detection of AA,DA,and UA with satisfactory results on actual samples.
