In order to investigate the variation in soil physical and chemical properties and nutrients in the mountainous areas in southern Ningxia, and to provide a theoretical basis for fertilization management in local farml...In order to investigate the variation in soil physical and chemical properties and nutrients in the mountainous areas in southern Ningxia, and to provide a theoretical basis for fertilization management in local farmland, the soil p H, total salt content,crop root length, root weight, soil organic matter, available nitrogen, total nitrogen, total phosphorous and total potassium in different fertilization treatments were measured from 2010 to 2016. Multiple comparisons of the data were performed using Duncan's new multiple range test. The results indicated that in the 0-20 cm soil layer, soil p H value and total salt content changed in different patterns, and varied greatly from 2010 to 2016(P<0.05). The changes of both root length and root weight of millet over time fitted S-shaped curves. The root length and root weight in the four fertilization treatments(Treatment 2 to Treatment5) increased faster than those in the control(Treatment 1). The soil organic matter content in all the five treatments gradually increased from 2010 to 2016. The content of alkaline hydrolyzable nitrogen in soil rapidly increased in the first two to three years of the experiment, followed by a slow increase or decrease in 2013, and then raised rapidly again from 2014 to 2016.The soil total nitrogen content varied significantly from 2010 to 2016. The total phosphorus content in soil changed in a different pattern from that of total nitrogen content. The seven-year field trails revealed that soil p H, total salt content, root length, root weight and soil nutrient all changed with the increase of fertilizer level, and that long-term fertilization is of significance for maintaining soil fertility, improving soil quality and reducing soil salinization.展开更多
Pinellia ternata has a long history of medicinal use in China, Japan, and Korea. Herein, we present a sensitive, selective, and robust HPLC method for the simultaneous determination of 6 organic acids （oxalic acid, m...Pinellia ternata has a long history of medicinal use in China, Japan, and Korea. Herein, we present a sensitive, selective, and robust HPLC method for the simultaneous determination of 6 organic acids （oxalic acid, malic acid, citric acid, formic acid, acetic acid, and succinic acid）, 3 nucleosides （uridine, guanosine hydrate, and adenosine）, and ephedrine in P. ternata. The Rhizoma pinelliae samples were collected from different parts of Southwest China, and the 10 constituents were detected at a wavelength of 210 nm. Chromatographic separation was achieved on a Boston Green ODS reversed-phase column along with a gradient mobile phase of methanol and phosphate buffer （pH 2.3, 10 mmol/L, v/v） at a flow rate of 1.0 mL/min. The range of recovery was between 90.8% and 101.9%, and the calibration curves showed high linearity. The relative standard deviations of the new method were less than 3.0% for intra- and inter-day analyses. All samples were stable for at least 48 h. The abundance of the 10 compounds were dependent on their specific locations. The new HPLC method is a powerful technique for the quality control ofP. Ternata.展开更多
Based on literature data and shipboard observations,this study investigated the main environmental characteristics of the seafloor topography,current field,front,and upwelling that are closely related to hypoxia occur...Based on literature data and shipboard observations,this study investigated the main environmental characteristics of the seafloor topography,current field,front,and upwelling that are closely related to hypoxia occurrence off the Changjiang estuary.The physical processes of the plume front and upwelling off the Changjiang estuary in summer were coupled.The vertical distribution pattern of the plume front was closely related to the upwelling.By reviewing and analyzing the historical summer hypoxia events off the Changjiang estuary,we statistically demonstrated the spatial structure of the horizontal distribution of the hypoxic zone and investigated the location of occurrence zone of the hypoxia.We found that the dissolved oxygen(DO)concentration on the inner continental shelf off the estuary showed a"V"shape in relation to station depth.Therefore,we noted that the hypoxic water on the inner continental shelf mostly occurred on the slopes with steep seafloor topography.Base on the current understanding of the hypoxic mechanisms off the Changjiang estuary,we analyzed the biogeochemical mechanisms that could cause the steep terrain off the Changjiang estuary to become the main areas prone to summer hypoxia and explained the internal relations between the location of the hypoxic zone on the slopes and the plume front and upwelling.The plume front and upwelling off the Changjiang estuary and their coupling were important driving forces of summer hypoxia.The continuous supply of nutrients affected by the interaction of the plume front extension of the Changjiang Diluted Water(CDW)and upwelling and the favorable light conditions were important mechanisms causing the phytoplankton blooms and benthic hypoxia off the Changjiang estuary in summer.By analyzing oxygen utilization,organic carbon mineralization,and nutrient regeneration in the hypoxic zone,we observed that the significant oxygen utilization process off the Changjiang estuary in summer also mainly occurred near the steep slopes with front and upwelling features and confirmed the apparent nutrient loss in the benthic hypoxic zone.Meanwhile,our analysis revealed that the sediment resuspension in the benthic boundary layer in the mud areas off the Changjiang estuary could also affect the oxygen utilization and mineralization of organic carbon and nutrient recycling and regeneration.This study also demonstrated that the steep terrain off the Changjiang estuary was the main location for summer acidification,and the coupling between the plume front and upwelling on the steep slopes was an important physical driving force inducing summer benthic acidification.Finally,we discussed issues to address in future studies of the hypoxic zone and water acidification off the Changjiang estuary.展开更多
In this paper, we report organic carbon isotopic characterizations from two loess sequences （JY and GL）, spanning the last 20 ka, from the northwest Chinese Loess Plateau （CLP）. The results indicate that the veget...In this paper, we report organic carbon isotopic characterizations from two loess sequences （JY and GL）, spanning the last 20 ka, from the northwest Chinese Loess Plateau （CLP）. The results indicate that the vegetation type is nearly pure C3 plants in the studied region during the Holocene. In contrast to other reported loess sequences in the central-southeast CLP, the relative abundance of the C4 plants decreases from southeast to northwest, with the vegetation types changing from pure C3 to a C4/C3 mixture should near 36°N in the Holocene. From the perspective of the modem temperature and precipitation distribution, the summer temperature has no obvious change at the same latitude, but there are differences in the summer precipi- tation, which exhibit an obvious increase from west to east. Further analysis indicated that the C4 plant abundance decreases with the decreasing summer season precipitation from the southeast to the northwest CLP during the Holocene. We suggest that with the absence of favorable precipitation condition, increasing temperature and decreasing atmospheric CO2 concentration are insufficient to drive an expansion of the C4 plants on the CLP in the Holocene. According to a Holocene precipitation recon- struction, a ＂threshold value＂ of summer precipitation existed, which mainly controlled the expansion of C4 plants. Compared with the modern δ13Csom and climate data on the CLP, both the Holocene and the present ＂threshold value＂ are near the 360-mm summer precipitation line, although the present precipitation line turned slightly southwestward. Our results provide new insights for further research on the C4/C3 variations with precipi- tation and the relationship to global C4/C3 change.展开更多
基金Supported by National Grain and Sorghum Industry Technical System(CARS-06-13.5-A18)Program for the Integrated Development of the Primary,Secondary and Tertiary Sectors in Rural Area of Ningxia(YES-06-08)
文摘In order to investigate the variation in soil physical and chemical properties and nutrients in the mountainous areas in southern Ningxia, and to provide a theoretical basis for fertilization management in local farmland, the soil p H, total salt content,crop root length, root weight, soil organic matter, available nitrogen, total nitrogen, total phosphorous and total potassium in different fertilization treatments were measured from 2010 to 2016. Multiple comparisons of the data were performed using Duncan's new multiple range test. The results indicated that in the 0-20 cm soil layer, soil p H value and total salt content changed in different patterns, and varied greatly from 2010 to 2016(P<0.05). The changes of both root length and root weight of millet over time fitted S-shaped curves. The root length and root weight in the four fertilization treatments(Treatment 2 to Treatment5) increased faster than those in the control(Treatment 1). The soil organic matter content in all the five treatments gradually increased from 2010 to 2016. The content of alkaline hydrolyzable nitrogen in soil rapidly increased in the first two to three years of the experiment, followed by a slow increase or decrease in 2013, and then raised rapidly again from 2014 to 2016.The soil total nitrogen content varied significantly from 2010 to 2016. The total phosphorus content in soil changed in a different pattern from that of total nitrogen content. The seven-year field trails revealed that soil p H, total salt content, root length, root weight and soil nutrient all changed with the increase of fertilizer level, and that long-term fertilization is of significance for maintaining soil fertility, improving soil quality and reducing soil salinization.
基金National Science & Technology Project of China(Grant No.2011BAI13B03)
文摘Pinellia ternata has a long history of medicinal use in China, Japan, and Korea. Herein, we present a sensitive, selective, and robust HPLC method for the simultaneous determination of 6 organic acids （oxalic acid, malic acid, citric acid, formic acid, acetic acid, and succinic acid）, 3 nucleosides （uridine, guanosine hydrate, and adenosine）, and ephedrine in P. ternata. The Rhizoma pinelliae samples were collected from different parts of Southwest China, and the 10 constituents were detected at a wavelength of 210 nm. Chromatographic separation was achieved on a Boston Green ODS reversed-phase column along with a gradient mobile phase of methanol and phosphate buffer （pH 2.3, 10 mmol/L, v/v） at a flow rate of 1.0 mL/min. The range of recovery was between 90.8% and 101.9%, and the calibration curves showed high linearity. The relative standard deviations of the new method were less than 3.0% for intra- and inter-day analyses. All samples were stable for at least 48 h. The abundance of the 10 compounds were dependent on their specific locations. The new HPLC method is a powerful technique for the quality control ofP. Ternata.
基金supported by the National Natural Science Foundation of China(Grant Nos.41206068&41620104001)the National Natural Science Foundation-Shandong Province Joint Fund for Marine Science Research Center(Grant No.U1406403)+4 种基金the Basic Scientific Fund for National Public Research Institutes of China(Grant No.2016S/Q08)the Open Fund of the Key Laboratory of Marine Ecology and Environmental Sciences,Institute of Oceanology,Chinese Academy of Sciences and the Laboratory of Marine Ecology and Environmental ScienceQingdao National Laboratory for Marine Science and Technology(Grant No.KLMEES201603)the National Basic Research Program of China(Grant No.2010CB428703)the National Project of Comprehensive Investigation and Research of the Coastal Seas of China(Grant No.908-ZC-I-03)
文摘Based on literature data and shipboard observations,this study investigated the main environmental characteristics of the seafloor topography,current field,front,and upwelling that are closely related to hypoxia occurrence off the Changjiang estuary.The physical processes of the plume front and upwelling off the Changjiang estuary in summer were coupled.The vertical distribution pattern of the plume front was closely related to the upwelling.By reviewing and analyzing the historical summer hypoxia events off the Changjiang estuary,we statistically demonstrated the spatial structure of the horizontal distribution of the hypoxic zone and investigated the location of occurrence zone of the hypoxia.We found that the dissolved oxygen(DO)concentration on the inner continental shelf off the estuary showed a"V"shape in relation to station depth.Therefore,we noted that the hypoxic water on the inner continental shelf mostly occurred on the slopes with steep seafloor topography.Base on the current understanding of the hypoxic mechanisms off the Changjiang estuary,we analyzed the biogeochemical mechanisms that could cause the steep terrain off the Changjiang estuary to become the main areas prone to summer hypoxia and explained the internal relations between the location of the hypoxic zone on the slopes and the plume front and upwelling.The plume front and upwelling off the Changjiang estuary and their coupling were important driving forces of summer hypoxia.The continuous supply of nutrients affected by the interaction of the plume front extension of the Changjiang Diluted Water(CDW)and upwelling and the favorable light conditions were important mechanisms causing the phytoplankton blooms and benthic hypoxia off the Changjiang estuary in summer.By analyzing oxygen utilization,organic carbon mineralization,and nutrient regeneration in the hypoxic zone,we observed that the significant oxygen utilization process off the Changjiang estuary in summer also mainly occurred near the steep slopes with front and upwelling features and confirmed the apparent nutrient loss in the benthic hypoxic zone.Meanwhile,our analysis revealed that the sediment resuspension in the benthic boundary layer in the mud areas off the Changjiang estuary could also affect the oxygen utilization and mineralization of organic carbon and nutrient recycling and regeneration.This study also demonstrated that the steep terrain off the Changjiang estuary was the main location for summer acidification,and the coupling between the plume front and upwelling on the steep slopes was an important physical driving force inducing summer benthic acidification.Finally,we discussed issues to address in future studies of the hypoxic zone and water acidification off the Changjiang estuary.
基金supported by the Strategic Leading Science and Technology Special Project(XDA05120402)the Open Fund for the State Key Laboratory of Loess and Quaternary Geology(SKLLQG1119)
文摘In this paper, we report organic carbon isotopic characterizations from two loess sequences （JY and GL）, spanning the last 20 ka, from the northwest Chinese Loess Plateau （CLP）. The results indicate that the vegetation type is nearly pure C3 plants in the studied region during the Holocene. In contrast to other reported loess sequences in the central-southeast CLP, the relative abundance of the C4 plants decreases from southeast to northwest, with the vegetation types changing from pure C3 to a C4/C3 mixture should near 36°N in the Holocene. From the perspective of the modem temperature and precipitation distribution, the summer temperature has no obvious change at the same latitude, but there are differences in the summer precipi- tation, which exhibit an obvious increase from west to east. Further analysis indicated that the C4 plant abundance decreases with the decreasing summer season precipitation from the southeast to the northwest CLP during the Holocene. We suggest that with the absence of favorable precipitation condition, increasing temperature and decreasing atmospheric CO2 concentration are insufficient to drive an expansion of the C4 plants on the CLP in the Holocene. According to a Holocene precipitation recon- struction, a ＂threshold value＂ of summer precipitation existed, which mainly controlled the expansion of C4 plants. Compared with the modern δ13Csom and climate data on the CLP, both the Holocene and the present ＂threshold value＂ are near the 360-mm summer precipitation line, although the present precipitation line turned slightly southwestward. Our results provide new insights for further research on the C4/C3 variations with precipi- tation and the relationship to global C4/C3 change.
