Nitrogen(N)and phosphorus(P)are two essential nutrients that determine plant growth and many nutrient cycling processes.Increasing N and P deposition is an important driver of ecosystem changes.However,in contrast to ...Nitrogen(N)and phosphorus(P)are two essential nutrients that determine plant growth and many nutrient cycling processes.Increasing N and P deposition is an important driver of ecosystem changes.However,in contrast to numerous studies about the impacts of nutrient addition on forests and temperate grasslands,how plant foliar stoichiometry and nutrient resorption respond to N and P addition in alpine grasslands is poorly understood.Therefore,we conducted an N and P addition experiment(involving control,N addition,P addition,and N+P addition)in an alpine grassland on Kunlun Mountains(Xinjiang Uygur Autonomous Region,China)in 2016 and 2017 to investigate the changes in leaf nutrient concentrations(i.e.,leaf N,Leaf P,and leaf N:P ratio)and nutrient resorption efficiency of Seriphidium rhodanthum and Stipa capillata,which are dominant species in this grassland.Results showed that N addition has significant effects on soil inorganic N(NO_(3)^(-)-N and NH_(4)^(+)-N)and leaf N of both species in the study periods.Compared with green leaves,leaf nutrient concentrations and nutrient resorption efficiency in senesced leaves of S.rhodanthum was more sensitive to N addition,whereas N addition influenced leaf N and leaf N:P ratio in green and senesced leaves of S.capillata.N addition did not influence N resorption efficiency of the two species.P addition and N+P addition significantly improved leaf P and had a negative effect on P resorption efficiency of the two species in the study period.These influences on plants can be explained by increasing P availability.The present results illustrated that the two species are more sensitive to P addition than N addition,which implies that P is the major limiting factor in the studied alpine grassland ecosystem.In addition,an interactive effect of N+P addition was only discernable with respect to soil availability,but did not affect plants.Therefore,exploring how nutrient characteristics and resorption response to N and P addition in the alpine grassland is important to understand nutrient use strategy of plants in terrestrial ecosystems.展开更多
N, O-carboxymethyl chitosan （NOCC） composite nanofiltration （NF） membranes were prepared by coating and cross-linking. The fermentation effluent from a wine factory was treated with the resulting NOCC/polysulfone ...N, O-carboxymethyl chitosan （NOCC） composite nanofiltration （NF） membranes were prepared by coating and cross-linking. The fermentation effluent from a wine factory was treated with the resulting NOCC/polysulfone （PSF） composite NF membranes. The permeate flux and the removal efficiencies of the resulting NF membranes for the color, chemical oxygen demand （CODcr）, total organic carbon （TOC）, and conductivity of the fermentation effluent were investigated in relation to the driving pressure, the feed flow, and the operation time. The permeate flux and the removal efficiencies were found to increase with the increase of the driving pressure or the feed flow. At 0.40 MPa and ambient temperature the removal efficiencies were 95.5%, 70.7%, 72.6%, and 31.6% for color, CODcr, TOC, and conductivity, respectively. The membrane was found to be stable over a 10-h ooeration for the fermentation effluent treatment.展开更多
Attitudes regarding traditional energy sources have shifted toward renewable resources. Specifically, short-rotation woody crop supply systems have become more prevalent for biomass and biofuel production. However, a ...Attitudes regarding traditional energy sources have shifted toward renewable resources. Specifically, short-rotation woody crop supply systems have become more prevalent for biomass and biofuel production. However, a number of factors such as environmental and inherent resource availability can limit tree production. Given the intensified demand for wood biomass production, forest and plantation management practices are focusing on increasing productivity. Fertilizer application, while generally one of the least expensive silvicultural tools, can become costly if application rates exceed nutrient uptake or demand of the trees especially if it does not result in additional biomass production. We investigated the effect of water and varying levels of nitrogen application (56, 112, and 224 kg·N·haǃ·yrǃ) on nutrient content, resorption efficiency and proficiency, N:P and the relationship with ANPP, as well as leaf- and canopy-level nutrient use efficiency of nitrogen, phosphorus, and potassium for Populus deltoides, Quercus pagoda, and Platanus occidentalis. P. deltoides and P. occidentalis reached their maximum nitrogen budget with the application of water suggesting old agricultural fields may have sufficient nutrient levels to sustain short-rotation woody crops negating the application of additional nitrogen for these two species. Additionally, for P. deltoides and Q. pagoda application of nitrogen appeared to increase the uptake of phosphorus however, resorption efficiency for these two species were more similar to studies conducted on nutrient poor sites. Nutrient resorption proficiency for all three nutrients and all three species were at levels below the highest rates of nitrogen application. These findings suggest maximum biomass production may not necessarily be tied to maximum nutrient application.展开更多
钙钛矿太阳能电池(perovskite solar cells,PSCs)由于光电转换效率高、制备工艺简单、成本低等优势受到广泛关注,电池效率已从3.8%提升到25.7%。目前,对基于SnO_(2)电子传输层的n-i-p型平板结构电池的研究越来越多,但存在着工艺可重复...钙钛矿太阳能电池(perovskite solar cells,PSCs)由于光电转换效率高、制备工艺简单、成本低等优势受到广泛关注,电池效率已从3.8%提升到25.7%。目前,对基于SnO_(2)电子传输层的n-i-p型平板结构电池的研究越来越多,但存在着工艺可重复性差、效率低等问题。针对n-i-p型平板结构PSCs的制备进行了系统的研究,包括导电基底的选择、钙钛矿制备工艺参数的优化以及电池存储环境。结果证明,上述参数对于电池均具有重要影响,并结合扫描电子显微镜、X射线衍射、吸收光谱分析了原因。在最优工艺条件下(掺锡氧化铟基底,PbI_(2)退火温度70℃(1 min),胺盐溶液滴加后静置时间不超过5 s,存储湿度4.5%),器件平均效率达到21.85%,最高效率达到23.47%,迟滞可忽略,具有良好的可重复性。研究结果可为制备重复性好、光电转换效率高的PSCs提供科学支撑。展开更多
For wastewater treatment in rural areas, a novel three-stage step-feed wastewater treatment system, combined with a drop-aeration biofilm process, was tested in the laboratory to investigate its performance in removin...For wastewater treatment in rural areas, a novel three-stage step-feed wastewater treatment system, combined with a drop-aeration biofilm process, was tested in the laboratory to investigate its performance in removing suspended solids （SS）, chemical oxygen demand （COD）, NH4＋-N, total nitrogen （TN）, and total phosphorus （TP）. The removal rates of SS, COD and NH4＋-N were 90%, 80%, and 90% in efluent concentrations less than 10 mg/L, 50 mg/L and 8 mg/L, respectively. The TP removal rate was less satisfactory. The C/N ratio in the raw wastewater was often less than 3.5, and the removal efficiency of TN was therefore limited. A carbon-release batch experiment was carried out to measure the feasibility of enhancing denitrification at low influent C/N ratios. The result showed that the C/N could be over 9.0 in the supernatant. Polymerase chain reaction denaturing gradient gel electrophoresis technology was used to reveal the changes in the bacterial community during different stages of the integrated step-feed biofilm process. The results showed that banding patterns and the distribution of dominant bands for the same experimental period in different aerobic zones were similar. Phylogenetic analysis indicated that lanes 10, 11 and 12, which presented three aerobic zones at the same operation period, had the closest phylogenetic relationship among the lanes.展开更多
研究了进水N/P对MUCT(modified university of cape town)工艺脱氮除磷性能的影响。结果表明,在低N/P(N/P=3.5～5.5)条件下,当进水N/P升高时,混合液回流2比值加大,缺氧吸磷率增加,对TP的去除率在93%以上;在高N/P(N/P=7.7～10.7)条件下,...研究了进水N/P对MUCT(modified university of cape town)工艺脱氮除磷性能的影响。结果表明,在低N/P(N/P=3.5～5.5)条件下,当进水N/P升高时,混合液回流2比值加大,缺氧吸磷率增加,对TP的去除率在93%以上;在高N/P(N/P=7.7～10.7)条件下,当进水N/P升高时,第2缺氧区硝酸盐氮浓度增加,缺氧吸磷率增加;随着N/P的升高,氮的同化去除率下降,同化作用对总氮的去除贡献减小;随着N/P的升高,好氧吸磷速率下降,硝化速率增加,出水氨氮浓度较低,在3.3 mg/L以下。展开更多
基金This research was supported by the National Natural Science Foundation of China(41807335)the Shandong Provincial Natural Science Foundation,China(ZR2020MC040)+2 种基金the National Key Technology Research and Development Program of China(2019YFC0507602-2)the Youth Innovation Promotion Association of the Chinese Academy of Sciences(2020434)the National Postdoctoral Program for Innovative Talents(BX201700279).
文摘Nitrogen(N)and phosphorus(P)are two essential nutrients that determine plant growth and many nutrient cycling processes.Increasing N and P deposition is an important driver of ecosystem changes.However,in contrast to numerous studies about the impacts of nutrient addition on forests and temperate grasslands,how plant foliar stoichiometry and nutrient resorption respond to N and P addition in alpine grasslands is poorly understood.Therefore,we conducted an N and P addition experiment(involving control,N addition,P addition,and N+P addition)in an alpine grassland on Kunlun Mountains(Xinjiang Uygur Autonomous Region,China)in 2016 and 2017 to investigate the changes in leaf nutrient concentrations(i.e.,leaf N,Leaf P,and leaf N:P ratio)and nutrient resorption efficiency of Seriphidium rhodanthum and Stipa capillata,which are dominant species in this grassland.Results showed that N addition has significant effects on soil inorganic N(NO_(3)^(-)-N and NH_(4)^(+)-N)and leaf N of both species in the study periods.Compared with green leaves,leaf nutrient concentrations and nutrient resorption efficiency in senesced leaves of S.rhodanthum was more sensitive to N addition,whereas N addition influenced leaf N and leaf N:P ratio in green and senesced leaves of S.capillata.N addition did not influence N resorption efficiency of the two species.P addition and N+P addition significantly improved leaf P and had a negative effect on P resorption efficiency of the two species in the study period.These influences on plants can be explained by increasing P availability.The present results illustrated that the two species are more sensitive to P addition than N addition,which implies that P is the major limiting factor in the studied alpine grassland ecosystem.In addition,an interactive effect of N+P addition was only discernable with respect to soil availability,but did not affect plants.Therefore,exploring how nutrient characteristics and resorption response to N and P addition in the alpine grassland is important to understand nutrient use strategy of plants in terrestrial ecosystems.
基金the Special Funds for Major State Basic Research Program of China(2003CB615706)
文摘N, O-carboxymethyl chitosan （NOCC） composite nanofiltration （NF） membranes were prepared by coating and cross-linking. The fermentation effluent from a wine factory was treated with the resulting NOCC/polysulfone （PSF） composite NF membranes. The permeate flux and the removal efficiencies of the resulting NF membranes for the color, chemical oxygen demand （CODcr）, total organic carbon （TOC）, and conductivity of the fermentation effluent were investigated in relation to the driving pressure, the feed flow, and the operation time. The permeate flux and the removal efficiencies were found to increase with the increase of the driving pressure or the feed flow. At 0.40 MPa and ambient temperature the removal efficiencies were 95.5%, 70.7%, 72.6%, and 31.6% for color, CODcr, TOC, and conductivity, respectively. The membrane was found to be stable over a 10-h ooeration for the fermentation effluent treatment.
文摘Attitudes regarding traditional energy sources have shifted toward renewable resources. Specifically, short-rotation woody crop supply systems have become more prevalent for biomass and biofuel production. However, a number of factors such as environmental and inherent resource availability can limit tree production. Given the intensified demand for wood biomass production, forest and plantation management practices are focusing on increasing productivity. Fertilizer application, while generally one of the least expensive silvicultural tools, can become costly if application rates exceed nutrient uptake or demand of the trees especially if it does not result in additional biomass production. We investigated the effect of water and varying levels of nitrogen application (56, 112, and 224 kg·N·haǃ·yrǃ) on nutrient content, resorption efficiency and proficiency, N:P and the relationship with ANPP, as well as leaf- and canopy-level nutrient use efficiency of nitrogen, phosphorus, and potassium for Populus deltoides, Quercus pagoda, and Platanus occidentalis. P. deltoides and P. occidentalis reached their maximum nitrogen budget with the application of water suggesting old agricultural fields may have sufficient nutrient levels to sustain short-rotation woody crops negating the application of additional nitrogen for these two species. Additionally, for P. deltoides and Q. pagoda application of nitrogen appeared to increase the uptake of phosphorus however, resorption efficiency for these two species were more similar to studies conducted on nutrient poor sites. Nutrient resorption proficiency for all three nutrients and all three species were at levels below the highest rates of nitrogen application. These findings suggest maximum biomass production may not necessarily be tied to maximum nutrient application.
文摘钙钛矿太阳能电池(perovskite solar cells,PSCs)由于光电转换效率高、制备工艺简单、成本低等优势受到广泛关注,电池效率已从3.8%提升到25.7%。目前,对基于SnO_(2)电子传输层的n-i-p型平板结构电池的研究越来越多,但存在着工艺可重复性差、效率低等问题。针对n-i-p型平板结构PSCs的制备进行了系统的研究,包括导电基底的选择、钙钛矿制备工艺参数的优化以及电池存储环境。结果证明,上述参数对于电池均具有重要影响,并结合扫描电子显微镜、X射线衍射、吸收光谱分析了原因。在最优工艺条件下(掺锡氧化铟基底,PbI_(2)退火温度70℃(1 min),胺盐溶液滴加后静置时间不超过5 s,存储湿度4.5%),器件平均效率达到21.85%,最高效率达到23.47%,迟滞可忽略,具有良好的可重复性。研究结果可为制备重复性好、光电转换效率高的PSCs提供科学支撑。
基金supported by Chinese Academy of Sciences (No. kzcx1-yw-06-20)the special fund from the State Key Laboratory of Environmental Aquatic Chemistry(No. 09Y06ESPCR)
文摘For wastewater treatment in rural areas, a novel three-stage step-feed wastewater treatment system, combined with a drop-aeration biofilm process, was tested in the laboratory to investigate its performance in removing suspended solids （SS）, chemical oxygen demand （COD）, NH4＋-N, total nitrogen （TN）, and total phosphorus （TP）. The removal rates of SS, COD and NH4＋-N were 90%, 80%, and 90% in efluent concentrations less than 10 mg/L, 50 mg/L and 8 mg/L, respectively. The TP removal rate was less satisfactory. The C/N ratio in the raw wastewater was often less than 3.5, and the removal efficiency of TN was therefore limited. A carbon-release batch experiment was carried out to measure the feasibility of enhancing denitrification at low influent C/N ratios. The result showed that the C/N could be over 9.0 in the supernatant. Polymerase chain reaction denaturing gradient gel electrophoresis technology was used to reveal the changes in the bacterial community during different stages of the integrated step-feed biofilm process. The results showed that banding patterns and the distribution of dominant bands for the same experimental period in different aerobic zones were similar. Phylogenetic analysis indicated that lanes 10, 11 and 12, which presented three aerobic zones at the same operation period, had the closest phylogenetic relationship among the lanes.
文摘研究了进水N/P对MUCT(modified university of cape town)工艺脱氮除磷性能的影响。结果表明,在低N/P(N/P=3.5～5.5)条件下,当进水N/P升高时,混合液回流2比值加大,缺氧吸磷率增加,对TP的去除率在93%以上;在高N/P(N/P=7.7～10.7)条件下,当进水N/P升高时,第2缺氧区硝酸盐氮浓度增加,缺氧吸磷率增加;随着N/P的升高,氮的同化去除率下降,同化作用对总氮的去除贡献减小;随着N/P的升高,好氧吸磷速率下降,硝化速率增加,出水氨氮浓度较低,在3.3 mg/L以下。
