The strong adaptability of Broussonetia papyrifera （L.） Vent. to low phosphorus （P） conditions can be attributed to the large amount of root-exuded organic acids and the high efficiency of P extraction. However, m...The strong adaptability of Broussonetia papyrifera （L.） Vent. to low phosphorus （P） conditions can be attributed to the large amount of root-exuded organic acids and the high efficiency of P extraction. However, microelement contents are influenced by low-P stress, and their effects on the photosynthetic capability of B. pa- pyrifera remain unknown. In this study, we investigated the effects of low-P treatment on net photosynthetic rate （PN）; chlorophyll a fluorescence （ChlF） characteristics; and Fe, Mn, Cu, and Zn contents of B. papyrifera and Morus alba L. seedlings. Results show that B. papyrifera exhibited better photosynthetic capability under moderate P defi- ciency （0.125, 0.063, and 0.031 mmol/L P treatments）, whereas the photosynthetic capability of M. alba decreased under moderate and severe P deficiency （0.016 and 0 mmol/L P treatments）. Under moderate P deficiency, the decrease in Cu and Zn contents in B. papyrifera was lower than that in M. alba. Under severe P deficiency, a consid- erable decrease of photosynthetic capability in B. pa- pyrifera and M. alba was associated with low Cu and Zn contents. The PN of the two Moraceae species exhibited a better correlation with Cu and Zn contents than with Fe or Mn content. P deficiency could not only decrease cyclic photophorylation and photosynthetic efficiency, but could also affect the stability of thylakoid membrane structureand electron transport efficiency by influencing the con- tents of Cu or Zn, thereby affecting photosynthesis.展开更多
A chert-phosphorite unit from the Sugetbrak section in the Tarim Basin was analyzed for rare earth elements(Ce,Eu),redox sensitive proxies,and carbon isotopic compositions(??13C carb and??13C org)in the lower Yurtus F...A chert-phosphorite unit from the Sugetbrak section in the Tarim Basin was analyzed for rare earth elements(Ce,Eu),redox sensitive proxies,and carbon isotopic compositions(??13C carb and??13C org)in the lower Yurtus Formation of the Early Cambrian period.Redox sensitive element ratios(Th/U,V/Cr,Ni/Co,and V/Sc)were employed to determine the palaeoenvironmental conditions during this period.The ratios indicated that the depositional environment of the chert-phosphorite-black shale unit ranged from suboxic to anoxic.Negative Ce and positive Eu anomalies in the chert-phosphorite assemblages of the studied Yurtus Formation indicated the existence of a redox-stratified ocean,similar to that of South China.Overturn or upward expansion of the deep water-mass probably reached the shallow marine zone after the formation of the Yurtus phosphorites.The characteristics of the negative Ce anomaly may be due to phosphoritic inheritance from the Ce-depleted signature of the overlying water column.Subsequent hydrothermal inputs and reduced detrital supplies of the deep water caused by the upwelling affected certain redox sensitive elements in the sedimentary basin.??13C carb and??13C org negative excursions in the Yurtus chert-phosphorite unit may be related to a transgression phase when episodic basinal upwelling moved12C-and P-rich waters from the pelagic basin floor to the continental shelf.Although carbon isotopic compositions in the Yurtus chert-phosphorite assemblages may have suffered from diagenetic alteration,they can be used to probe diagenetic conditions.Multi-proxy geochemical studies indicated that the??13C carb values of the Yurtus chert-phosphorite assemblages might be considered reflections of a predominantly suboxic environment that was subsequently affected by hydrothermal inputs due to the upwelling.展开更多
Tuite has been suggested as a potential reservoir for trace elements in the deep mantle,but no evidence confirms this supposition.By using a natural apatite as starting material,the trace-element-bearing tuite large c...Tuite has been suggested as a potential reservoir for trace elements in the deep mantle,but no evidence confirms this supposition.By using a natural apatite as starting material,the trace-element-bearing tuite large crystals were obtained under highpressure and high-temperature conditions(15 GPa and 1800 K).X-ray diffraction pattern and Micro-Raman spectrum of the run product confirm that tuite was synthesized.The concentrations of trace elements in tuite crystals were analyzed by laser ablation-inductively coupled plasma-mass spectrometry(LA-ICP-MS).The rare earth element patterns of tuite show enrichment of light rare earth elements relative to heavy rare earth elements.Tuite shows high concentrations of Th and Sr,and negative anomalies of Rb,Nb,and Hf.The results show that tuite can accommodate a large amount of trace elements.Tuite might be an important host to accommodate trace elements if there is much apatite subducted into the deep mantle.展开更多
基金supported by the project of the National Natural Science Foundation of China (No. 31301243)a project funded by the Priority Academic Program Development of Jiangsu higher education institutions (PAPD)+1 种基金the research foundation for introduce talents of Jiangsu university (13JDG030)the brainstorm project on social development of Guizhou Province (SY[2010]3043)
文摘The strong adaptability of Broussonetia papyrifera （L.） Vent. to low phosphorus （P） conditions can be attributed to the large amount of root-exuded organic acids and the high efficiency of P extraction. However, microelement contents are influenced by low-P stress, and their effects on the photosynthetic capability of B. pa- pyrifera remain unknown. In this study, we investigated the effects of low-P treatment on net photosynthetic rate （PN）; chlorophyll a fluorescence （ChlF） characteristics; and Fe, Mn, Cu, and Zn contents of B. papyrifera and Morus alba L. seedlings. Results show that B. papyrifera exhibited better photosynthetic capability under moderate P defi- ciency （0.125, 0.063, and 0.031 mmol/L P treatments）, whereas the photosynthetic capability of M. alba decreased under moderate and severe P deficiency （0.016 and 0 mmol/L P treatments）. Under moderate P deficiency, the decrease in Cu and Zn contents in B. papyrifera was lower than that in M. alba. Under severe P deficiency, a consid- erable decrease of photosynthetic capability in B. pa- pyrifera and M. alba was associated with low Cu and Zn contents. The PN of the two Moraceae species exhibited a better correlation with Cu and Zn contents than with Fe or Mn content. P deficiency could not only decrease cyclic photophorylation and photosynthetic efficiency, but could also affect the stability of thylakoid membrane structureand electron transport efficiency by influencing the con- tents of Cu or Zn, thereby affecting photosynthesis.
基金supported by National Natural Science Foundation of China(Grant No.41203023)National Basic Research Program of China(Grant No.2007CB411301)
文摘A chert-phosphorite unit from the Sugetbrak section in the Tarim Basin was analyzed for rare earth elements(Ce,Eu),redox sensitive proxies,and carbon isotopic compositions(??13C carb and??13C org)in the lower Yurtus Formation of the Early Cambrian period.Redox sensitive element ratios(Th/U,V/Cr,Ni/Co,and V/Sc)were employed to determine the palaeoenvironmental conditions during this period.The ratios indicated that the depositional environment of the chert-phosphorite-black shale unit ranged from suboxic to anoxic.Negative Ce and positive Eu anomalies in the chert-phosphorite assemblages of the studied Yurtus Formation indicated the existence of a redox-stratified ocean,similar to that of South China.Overturn or upward expansion of the deep water-mass probably reached the shallow marine zone after the formation of the Yurtus phosphorites.The characteristics of the negative Ce anomaly may be due to phosphoritic inheritance from the Ce-depleted signature of the overlying water column.Subsequent hydrothermal inputs and reduced detrital supplies of the deep water caused by the upwelling affected certain redox sensitive elements in the sedimentary basin.??13C carb and??13C org negative excursions in the Yurtus chert-phosphorite unit may be related to a transgression phase when episodic basinal upwelling moved12C-and P-rich waters from the pelagic basin floor to the continental shelf.Although carbon isotopic compositions in the Yurtus chert-phosphorite assemblages may have suffered from diagenetic alteration,they can be used to probe diagenetic conditions.Multi-proxy geochemical studies indicated that the??13C carb values of the Yurtus chert-phosphorite assemblages might be considered reflections of a predominantly suboxic environment that was subsequently affected by hydrothermal inputs due to the upwelling.
基金financially supported by National Natural Science Foundation of China(Grant No.40973045)
文摘Tuite has been suggested as a potential reservoir for trace elements in the deep mantle,but no evidence confirms this supposition.By using a natural apatite as starting material,the trace-element-bearing tuite large crystals were obtained under highpressure and high-temperature conditions(15 GPa and 1800 K).X-ray diffraction pattern and Micro-Raman spectrum of the run product confirm that tuite was synthesized.The concentrations of trace elements in tuite crystals were analyzed by laser ablation-inductively coupled plasma-mass spectrometry(LA-ICP-MS).The rare earth element patterns of tuite show enrichment of light rare earth elements relative to heavy rare earth elements.Tuite shows high concentrations of Th and Sr,and negative anomalies of Rb,Nb,and Hf.The results show that tuite can accommodate a large amount of trace elements.Tuite might be an important host to accommodate trace elements if there is much apatite subducted into the deep mantle.
