The species richness and propagule number of arbuscular mycorrhizal fungi(AMF)are high in intensively-managed agricultural soils.Past research has shown that AMF improve crop phosphorus(P)uptake under low soil P condi...The species richness and propagule number of arbuscular mycorrhizal fungi(AMF)are high in intensively-managed agricultural soils.Past research has shown that AMF improve crop phosphorus(P)uptake under low soil P conditions,however it is unclear if AMF play a role in high Olsen-P soils.In this study,we investigated whether native fungal benefits exist under high P input field conditions in-situ and contribute to P utilization.We installed in-grow tubes which were sealed with different membrane pore sizes(30 or 0.45μm)to allow or prevent AMF hyphae access to the hyphal compartment and prevent cotton roots from penetrating the chamber.We used the depletion of soil available P(Olsen-P)in the hyphae accessed compartment to indicate P uptake by the native AMF community.Our results showed that the native AMF mediated P depletion and microbial biomass P(MBP)turnover and caused the largest Olsen-P depletion ratio and MBP turnover ratio in the high P treatments(Olsen-P:78.29 mg kg^(-1)).The cotton roots in each fertilization regime were colonized by a unique AMF community and Glomus and Paraglomus were the dominant genera,implying the longterm fertilization regimes domesticated the AMF community.We conclude that native AMF caused the P depletion and P turnover even under high soil Olsen-P conditions.展开更多
In order to understand the melting processes that occur within recycled oceanic crust and mantle in a heterogeneous plume (e.g., that beneath the Hawaiian Islands), a series of high-pressure-high-temperature layered e...In order to understand the melting processes that occur within recycled oceanic crust and mantle in a heterogeneous plume (e.g., that beneath the Hawaiian Islands), a series of high-pressure-high-temperature layered experiments were performed at 2.9 GPa, 5 GPa, and 8 GPa, from 1300°C to 1650°C, using a fertile peridotite KLB-1 and N-MORB. Our experiments at conditions below the dry peridotite solidus produced melt compositions that ranged from basaltic andesite to tholeiite. An Opx reaction band formed between eclogite and peridotite layers, likely via chemical reaction between a silica-rich eclogite-derived partial melt and olivine in the peridotite matrix. At temperatures at or above the dry peridotite solidus, substantial melting occurred in both basalt and peridotite layers, and fully molten basalt melt and melt pockets from the peridotite layer combined. In our layered experiments, major and minor element contents in reacted melts closely matched those of Hawaiian tholeiite and picrite, except for Fe. Partial melts of anhydrous run products had ~55 - 57 wt% SiO2 at low temperature (i.e., were andesitic) and had ~50 - 53 wt% SiO2 at high temperatures, slightly below the dry peridotite solidus (i.e., were tholeiitic, and similar to those that occur during the Hawaii shield-building stage). Based on the Fe- and LREE-enriched signature in Hawaiian tholeiites, we propose that recycled components in the Hawaiian plume are not modern N-MORB, but are Fe-rich tholeiite;a lithology that was common in the Archaean and early Proterozoic. We have demonstrated that the entire compositional spectrum of Hawaiian tholeiites (basalt to picrite) can be formed by basalt-peridotite reactive melting near the dry solidus of peridotite. Based on these results, we propose that the potential temperature of the sub-Hawaiian plume may be much lower than previously estimated.展开更多
The intergranular corrosion （IGC） behavior of high nitrogen austenitic stainless steel （HNSS） sensitization treated at 650-950℃ was investigated by the double loop electrochemical potentiodynamic reactivation （D...The intergranular corrosion （IGC） behavior of high nitrogen austenitic stainless steel （HNSS） sensitization treated at 650-950℃ was investigated by the double loop electrochemical potentiodynamic reactivation （DL-EPR） method. The effects of the electrolytes, scan rate, sensitizing temperature on the susceptibility to IGC of HNSS were examined. The results show that the addi-tion of NaCl is an effective way to improve the formation of the cracking of a passive film in chromium-depleted zones during the reactivation scan. Decreasing the scan rate exhibits an obvious effect on the breakdown of the passive film. A solution with 2 mol/L H2SO4＋1 mol/L NaCl＋0.01 mol/L KSCN is suitable to check the susceptibility to IGC of HNSS at a sensitizing temperature of 650-950℃ at a suitable scan rate of 1.667 mV/s. Chromium depletion of HNSS is attributed to the precipitation of Cr2N which results in the susceptibility to IGC. The synergistic effect of Mo and N is suggested to play an important role in stabilizing the passive film to prevent the attack of IGC.展开更多
Cenozoic high\|K igneous rocks are widely distributed in eastern Tibet. These rocks are exposed as flows, dykes and small intrusions along a narrow north\|south trending zone, which follows Tertiary fold belts and the...Cenozoic high\|K igneous rocks are widely distributed in eastern Tibet. These rocks are exposed as flows, dykes and small intrusions along a narrow north\|south trending zone, which follows Tertiary fold belts and the Batang—Lijiang and Ailao Shan—Red River strike\|slip systems. Although several models were proposed to interpret their petrogenesis (Deng, 1989; Arnaud et al., 1991; Turner et al., 1996; Yin et al., 1995; Miller et al., 1999), their origin still remains hotly debated. Moreover, the published results were only focused on the high\|K igneous rocks resulted from partial melting of an enriched lithospheric mantle. Here, we present the detailed documents to testify the existence of a new kind of high\|K igneous rocks in eastern Tibet.Our new 39 Ar/ 40 Ar age data (Wang et al., 1999) and published age data for high\|K rocks in eastern Tibet show two distinctive magmatic episodes: one between 42Ma and 24Ma, and the other since ca.16Ma. They correspond to two types of high\|K magmatism in eastern Tibet. We name the older and younger groups as types Ⅰ and Ⅱ, respectively.展开更多
Compositional peculiarities of the siliceous high-Mg series(SHMS)rocks formed at the Archean-Paleoproterozoic boundary as a function of plume activity are discussed using example of Early Paleoproterozoic mafic volcan...Compositional peculiarities of the siliceous high-Mg series(SHMS)rocks formed at the Archean-Paleoproterozoic boundary as a function of plume activity are discussed using example of Early Paleoproterozoic mafic volcanic rocks of the Vodlozero Domain,Fennoscandian Shield.These rocks are characterized by wide variations in Mg#(33-67)and Cr contents(25-1123 ppm),LREE enrichment,and weakly negative_(εNd)(from-0.7 to-2.9).The high Gd/Yb ratio in the primitive high-Mg rocks of the Vodlozero Domain suggests their generation from a garnet-bearing source.At the same time,their negative _(εNd)in combination with LREE enrichment points to the crustal contamination.A new model was proposed to explain the remarkable global-scale similarity of SHMS.Such rocks can be generated by the contamination of a high-degree(30%)partial melt derived from a depleted mantle.The lower crustal sanukitoid-type rocks can be considered as a universal crustal contaminant.Modeling showed that such mixing can provide the observed narrow_(εNd)variations in Early Paleoproterozoic volcanics.The Neoarchean sanukitoid suites,which are widespread on all cratons,presumably composed the lower crust at the beginning of the Paleoproterozoic.Therefore,this mechanism can be considered universal for the genesis of the SHMS rocks.The high-to low-Cr rock series can be produced by the fractionation of the mafic melt coupled with an insignificant crustal assimilation of felsic end members of the sanukitoid suite of the Vodlozero Domain en route to the surface,as suggested by the positive correlation of_(εNd)with Cr and Mg#,negative correlation with Th,and slight decrease of_(εNd)in the more evolved varieties.展开更多
基金financially supported by the Beijing Natural Science Foundation,China(6202015)the National Natural Science Foundation of China(U1703232)the Hatch Project(ALA014-1-16016)funded by the National Institute of Food and Agriculture,US Department of Agriculture。
文摘The species richness and propagule number of arbuscular mycorrhizal fungi(AMF)are high in intensively-managed agricultural soils.Past research has shown that AMF improve crop phosphorus(P)uptake under low soil P conditions,however it is unclear if AMF play a role in high Olsen-P soils.In this study,we investigated whether native fungal benefits exist under high P input field conditions in-situ and contribute to P utilization.We installed in-grow tubes which were sealed with different membrane pore sizes(30 or 0.45μm)to allow or prevent AMF hyphae access to the hyphal compartment and prevent cotton roots from penetrating the chamber.We used the depletion of soil available P(Olsen-P)in the hyphae accessed compartment to indicate P uptake by the native AMF community.Our results showed that the native AMF mediated P depletion and microbial biomass P(MBP)turnover and caused the largest Olsen-P depletion ratio and MBP turnover ratio in the high P treatments(Olsen-P:78.29 mg kg^(-1)).The cotton roots in each fertilization regime were colonized by a unique AMF community and Glomus and Paraglomus were the dominant genera,implying the longterm fertilization regimes domesticated the AMF community.We conclude that native AMF caused the P depletion and P turnover even under high soil Olsen-P conditions.
文摘In order to understand the melting processes that occur within recycled oceanic crust and mantle in a heterogeneous plume (e.g., that beneath the Hawaiian Islands), a series of high-pressure-high-temperature layered experiments were performed at 2.9 GPa, 5 GPa, and 8 GPa, from 1300°C to 1650°C, using a fertile peridotite KLB-1 and N-MORB. Our experiments at conditions below the dry peridotite solidus produced melt compositions that ranged from basaltic andesite to tholeiite. An Opx reaction band formed between eclogite and peridotite layers, likely via chemical reaction between a silica-rich eclogite-derived partial melt and olivine in the peridotite matrix. At temperatures at or above the dry peridotite solidus, substantial melting occurred in both basalt and peridotite layers, and fully molten basalt melt and melt pockets from the peridotite layer combined. In our layered experiments, major and minor element contents in reacted melts closely matched those of Hawaiian tholeiite and picrite, except for Fe. Partial melts of anhydrous run products had ~55 - 57 wt% SiO2 at low temperature (i.e., were andesitic) and had ~50 - 53 wt% SiO2 at high temperatures, slightly below the dry peridotite solidus (i.e., were tholeiitic, and similar to those that occur during the Hawaii shield-building stage). Based on the Fe- and LREE-enriched signature in Hawaiian tholeiites, we propose that recycled components in the Hawaiian plume are not modern N-MORB, but are Fe-rich tholeiite;a lithology that was common in the Archaean and early Proterozoic. We have demonstrated that the entire compositional spectrum of Hawaiian tholeiites (basalt to picrite) can be formed by basalt-peridotite reactive melting near the dry solidus of peridotite. Based on these results, we propose that the potential temperature of the sub-Hawaiian plume may be much lower than previously estimated.
基金supported by the National Natural Science Foundation of China (No.50534010) and Baosteel Group Corporation
文摘The intergranular corrosion （IGC） behavior of high nitrogen austenitic stainless steel （HNSS） sensitization treated at 650-950℃ was investigated by the double loop electrochemical potentiodynamic reactivation （DL-EPR） method. The effects of the electrolytes, scan rate, sensitizing temperature on the susceptibility to IGC of HNSS were examined. The results show that the addi-tion of NaCl is an effective way to improve the formation of the cracking of a passive film in chromium-depleted zones during the reactivation scan. Decreasing the scan rate exhibits an obvious effect on the breakdown of the passive film. A solution with 2 mol/L H2SO4＋1 mol/L NaCl＋0.01 mol/L KSCN is suitable to check the susceptibility to IGC of HNSS at a sensitizing temperature of 650-950℃ at a suitable scan rate of 1.667 mV/s. Chromium depletion of HNSS is attributed to the precipitation of Cr2N which results in the susceptibility to IGC. The synergistic effect of Mo and N is suggested to play an important role in stabilizing the passive film to prevent the attack of IGC.
文摘Cenozoic high\|K igneous rocks are widely distributed in eastern Tibet. These rocks are exposed as flows, dykes and small intrusions along a narrow north\|south trending zone, which follows Tertiary fold belts and the Batang—Lijiang and Ailao Shan—Red River strike\|slip systems. Although several models were proposed to interpret their petrogenesis (Deng, 1989; Arnaud et al., 1991; Turner et al., 1996; Yin et al., 1995; Miller et al., 1999), their origin still remains hotly debated. Moreover, the published results were only focused on the high\|K igneous rocks resulted from partial melting of an enriched lithospheric mantle. Here, we present the detailed documents to testify the existence of a new kind of high\|K igneous rocks in eastern Tibet.Our new 39 Ar/ 40 Ar age data (Wang et al., 1999) and published age data for high\|K rocks in eastern Tibet show two distinctive magmatic episodes: one between 42Ma and 24Ma, and the other since ca.16Ma. They correspond to two types of high\|K magmatism in eastern Tibet. We name the older and younger groups as types Ⅰ and Ⅱ, respectively.
基金supported by the Russian Foundation for Basic Research (Project Nos.16-05-00708 and 15-05-01214)
文摘Compositional peculiarities of the siliceous high-Mg series(SHMS)rocks formed at the Archean-Paleoproterozoic boundary as a function of plume activity are discussed using example of Early Paleoproterozoic mafic volcanic rocks of the Vodlozero Domain,Fennoscandian Shield.These rocks are characterized by wide variations in Mg#(33-67)and Cr contents(25-1123 ppm),LREE enrichment,and weakly negative_(εNd)(from-0.7 to-2.9).The high Gd/Yb ratio in the primitive high-Mg rocks of the Vodlozero Domain suggests their generation from a garnet-bearing source.At the same time,their negative _(εNd)in combination with LREE enrichment points to the crustal contamination.A new model was proposed to explain the remarkable global-scale similarity of SHMS.Such rocks can be generated by the contamination of a high-degree(30%)partial melt derived from a depleted mantle.The lower crustal sanukitoid-type rocks can be considered as a universal crustal contaminant.Modeling showed that such mixing can provide the observed narrow_(εNd)variations in Early Paleoproterozoic volcanics.The Neoarchean sanukitoid suites,which are widespread on all cratons,presumably composed the lower crust at the beginning of the Paleoproterozoic.Therefore,this mechanism can be considered universal for the genesis of the SHMS rocks.The high-to low-Cr rock series can be produced by the fractionation of the mafic melt coupled with an insignificant crustal assimilation of felsic end members of the sanukitoid suite of the Vodlozero Domain en route to the surface,as suggested by the positive correlation of_(εNd)with Cr and Mg#,negative correlation with Th,and slight decrease of_(εNd)in the more evolved varieties.
