Atmospheric deposition of nitrogen(N)plays a significant role in shaping the structure and functioning of various terrestrial ecosystems worldwide.However,the magnitude of N deposition on grassland ecosystems in Centr...Atmospheric deposition of nitrogen(N)plays a significant role in shaping the structure and functioning of various terrestrial ecosystems worldwide.However,the magnitude of N deposition on grassland ecosystems in Central Asia still remains highly uncertain.In this study,a multi-data approach was adopted to analyze the distribution and amplitude of N deposition effects in Central Asia from 1979 to 2014 using a process-based denitrification decomposition(DNDC)model.Results showed that total vegetation carbon(C)in Central Asia was 0.35(±0.09)Pg C/a and the averaged water stress index(WSI)was 0.20(±0.02)for the whole area.Increasing N deposition led to an increase in the vegetation C of 65.56(±83.03)Tg C and slightly decreased water stress in Central Asia.Findings of this study will expand both our understanding and predictive capacity of C characteristics under future increases in N deposition,and also serve as a valuable reference for decision-making regarding water resources management and climate change mitigation in arid and semi-arid areas globally.展开更多
Stable isotope techniques have been proved useful as tools for studying the carbon (C) and nitrogen (N) biogeochemical cycles of ecosystem. This paper firstly introduced the basic principles and the distribution chara...Stable isotope techniques have been proved useful as tools for studying the carbon (C) and nitrogen (N) biogeochemical cycles of ecosystem. This paper firstly introduced the basic principles and the distribution characteristics of stable isotope, then reviewed the recent advances and applications of stable isotope in the C and N biogeochemical cycles of ecosystem. By applying the 13 C natural abundance technique, ecologists are able to understand the photosynthetic path and CO 2 fixation of plants, the CO 2 exchange and C balance status of ecosystem, the composition, distribution and turnover of soil organic C and the sources of organic matter in food webs, while by using the 13 C labeled technique, the effects of elevated CO 2 on the C processes of ecosystem and the sources and fate of organic matter in ecosystem can be revealed in detail. Differently, by applying the 15 N natural abundance technique, ecologists are able to analyze the biological N 2 -fixation, the N sources of ecosystem, the N transformation processes of ecosystem and the N trophic status in food webs, while by using the 15 N labeled technique, the sources, transformation and fate of N in ecosystem and the effects of N input on the ecosystem can be investigated in depth. The applications of both C and N isotope natural abundance and labeled techniques, combined with the elemental, other isotope ( 34 S) and molecular biomarker information, will be more propitious to the investigation of C and N cycle mechanisms. Finally, this paper concluded the problems existed in current researches, and put forward the perspective of stable isotope techniques in the studies on C and N biogeochemical cycles of ecosystem in the future.展开更多
This article reviews recent advances over the past and their relationship to climate change in China. The was 0.19-0.26 Pg C yr-1 for the 1980s and 1990s. 4 years in the study of the carbon-nitrogen cycling net carbon...This article reviews recent advances over the past and their relationship to climate change in China. The was 0.19-0.26 Pg C yr-1 for the 1980s and 1990s. 4 years in the study of the carbon-nitrogen cycling net carbon sink in the Chinese terrestrial ecosystem Both natural wetlands and the rice-paddy regions emitted 1.76 Tg and 6.62 Tg of CH4 per year for the periods 1995 2004 and 2005 2009, respectively. China emitted -1.1 Tg N20-N yr-1 to the atmosphere in 2004. Land soil contained -8.3 Pg N. The excess nitrogen stored in farmland of the Yangtze River basin reached 1.51 Tg N and 2.67 Tg N in 1980 and 1990, respectively. The outer Yangtze Estuary served as a moderate or significant sink of atmospheric CO2 except in autumn. Phytoplankton could take up carbon at a rate of 6.4 ×1011 kg yr-1 in the China Sea. The global ocean absorbed anthropogenic CO2 at the rates of 1.64 and 1.73 Pg C yr-1 for two sinmlations in the 1990s. Land net ecosystem production in China would increase until the mid-21st century then would decrease gradually under future climate change scenarios. This research should be strengthened in the future, including collection of more observation data, measurement of the soil organic carbon (SOC) loss and sequestration, evaluation of changes in SOC in deep soil layers, and the impacts of grassland management, carbon-nitrogen coupled effects, and development and improvement of various component models and of the coupled carbon cycle-climate model.展开更多
Southwest China is the primary area for damming rivers to produce hydroelectric energy and store water.River damming has changed hydrodynamic,chemical,and biological processes,which are related to sinks and sources of...Southwest China is the primary area for damming rivers to produce hydroelectric energy and store water.River damming has changed hydrodynamic,chemical,and biological processes,which are related to sinks and sources of greenhouse gases and carbon and nitrogen fluxes of different interfaces.Here,I provide an introduction to a river damming-related foundation,the National Key R&D Program of China(2016YTA0601000).Supported by the foundation,we carried out research on multiprocesses/multi-interfaces of carbon and nitrogen biogeochemical cycles in a dammed river system and have produced important results,as presented in this issue of the journal.展开更多
The carbon cycle of global inland waters is quantitatively comparable to other components in the global carbon budget. Among inland waters, a significant part is man-made lakes formed by damming rivers. Manmade lakes ...The carbon cycle of global inland waters is quantitatively comparable to other components in the global carbon budget. Among inland waters, a significant part is man-made lakes formed by damming rivers. Manmade lakes are undergoing a rapid increase in number and size. Human impacts and frequent algae blooms lead to it necessary to make a better constraint on their carbon cycles. Here, we make a primary estimation on the air–water CO_2 transfer flux through an algae bloom year for a subtropical man-made lake—Hongfeng Lake, Southwest China. To do this a new type of glass bottles was designed for content and isotopic analysis of DIC and other environmental parameters. At the early stage of algae bloom,CO_2 was transferred from the atmosphere to the lake with a net flux of 1.770 g·C·m^(-2). Later, the partial pressure(pCO_2) of the aqueous CO_2 increased rapidly and the lake outgassed to the atmosphere with a net flux of 95.727 g·C·m^(-2). In the remaining days, the lake again took up CO_2 from the atmosphere with a net flux of 14.804 g·C·m^(-2). As a whole, Lake Hongfeng released 4527 t C to the atmosphere, accounting for one-third of the atmosphere/soil CO_2 sequestered by chemical weathering in the whole drainage. With an empirical mode decomposition method, we found air temperature plays a major role in controlling water temperature, aqueous pCO_2 and hence CO_2 flux. This work indicates a necessity to make detailed and comprehensive carbon budgets in man-made lakes.展开更多
In agricultural systems, maintenance of soil organic matter has long been recognized as a strategy to reduce soil degradation. Manure amendments and green manures are management practices that can increase some nutrie...In agricultural systems, maintenance of soil organic matter has long been recognized as a strategy to reduce soil degradation. Manure amendments and green manures are management practices that can increase some nutrient contents and improve soil aggregation. We investigated the effects of 28 yr of winter planted green manure on soil aggregate-size distribution and aggregateassociated carbon(C) and nitrogen(N). The study was a randomized completed block design with three replicates. The treatments included rice-rice-fallow, rice-rice-rape, rice-rice-Chinese milk vetch and rice-rice-ryegrass. The experiment was established in 1982 on a silty light clayey paddy soil derived from Quaternary red clay(classified as Fe-Accumuli-Stagnic Anthrosols) with continuous early and late rice. In 2009, soil samples were collected(0-15 cm depth) from the field treatment plots and separated into water-stable aggregates of different sizes(i.e., 〉5, 2-5, 1-2, 0.5-1, 0.25-0.5 and 〈0.25 mm) by wet sieving. The long-term winter planted green manure significantly increased total C and N, and the formation of the 2-5-mm water-stable aggregate fraction. Compared with rice-rice-rape, rice-rice-Chinese milk vetch and rice-rice-ryegrass, the rice-rice-fallow significantly reduced 2-5-mm water-stable aggregates, with a significant redistribution of aggregates into micro-aggregates. Long-term winter planted green manure obviously improved C/N ratio and macro-aggregate-associated C and N. The highest contribution to soil fertility was from macro-aggregates of 2-5 mm in most cases.展开更多
Experimental studies were carried out on the purification of eutrophicTaihu Lake water by dynamic experiment using immobilized nitrogen cycle bacteria(INCB). The results showed that the eutrophic water of Taihu Lake c...Experimental studies were carried out on the purification of eutrophicTaihu Lake water by dynamic experiment using immobilized nitrogen cycle bacteria(INCB). The results showed that the eutrophic water of Taihu Lake can be purifiedeffectively as it passes through the experimental reactor into which some immobilizednitrogen cycle bacteria were put. The removal efficiencies for Total N (TN), NH4+-Nwith immobilized nitrogen cycle bacteria were 72.4% and 85.6%, respectively. It wasfound that the immobilized nitrogen cycle bacteria also have purificatory effect oneutrophic water of Taihu Lake at winter temperature (7°C), and that the removalmefficiencies for Total N (TN), NH4+-N were 55.6%, and 58.9%, respectively. Theremoval efficiencies for TN and NH4+-N depend on the time the water stays in theexperimental reactor.展开更多
This study uses the Life Cycle Analysis (LCA) to evaluate the magnitude of the environmental impact, in terms of global warming potential, and water footprint throughout the 20 years of useful life of a rural electric...This study uses the Life Cycle Analysis (LCA) to evaluate the magnitude of the environmental impact, in terms of global warming potential, and water footprint throughout the 20 years of useful life of a rural electrical energy concession comprised of 120Wp Households photovoltaic systems (HPS) in the isolated communities of San Martin, in the Peruvian Amazon region. On the other hand, due to the particular conditions of the system (installation, operation, maintenance, monthly tariff collection), it is necessary to know its real impact and sustainability;not only through the aforementioned environmental impact indicators, but also by energy intensity values required by the system throughout its life cycle. Therefore, this paper used the Cumulative energy demand (CED) method to determine the amount of energy taken from natural resources for each process involved in the LCA and calculated with this, i.e., the Energy Payback Time (EPBT) of the whole system. Likewise, the HPS has been environmentally compared to other case studies and the Peruvian Energy Mix, revealing a lower impact in the latter case and results within the range for stand-alone systems. Besides, the HPS shows a strong relation between energy production and O&M condition. Additionally, this study allows a further promotion of the use of this type of system in isolated areas, as well as the diversification of electricity generation in Peru.展开更多
The response patterns of microbial functional genes involved in biogeochemical cycles to cadaver decay is a central topic of recent environmental sciences.However,the response mechanisms and pathways of the functional...The response patterns of microbial functional genes involved in biogeochemical cycles to cadaver decay is a central topic of recent environmental sciences.However,the response mechanisms and pathways of the functional genes associated with the carbon(C)and nitrogen(N)cycling to cadaveric substances such as cadaverine and putrescine remain unclear.This study explored the variation of functional genes associated with C fixation,C degradation and N cycling and their influencing factors under cadaverine,putrescine and mixed treatments.Our results showed only putrescine significantly increased the alpha diversity of C fixation genes,while reducing the alpha diversity of N cycling genes in sediment.For the C cycling,the mixed treatment significantly decreased the total abundance of reductive acetyl-CoA pathway genes(i.e.,acsB and acsE)and lig gene linked to lignin degradation in water,while only significantly increasing the hydroxypropionate-hydroxybutylate cycle(i.e.,accA)gene abundance in sediment.For the N cycling,mixed treatment significantly decreased the abundance of the nitrification(i.e.,amoB),denitrification(i.e.,nirS3)genes in water and the assimilation pathway gene(i.e.,gdhA)in sediment.Environmental factors(i.e.,total carbon and total nitrogen)were all negatively associated with the genes of C and N cycling.Therefore,cadaverine and putrescine exposure may inhibit the pathway in C fixation and N cycling,while promoting C degradation.These findings can offer some new insight for the management of amine pollution caused by animal cadavers.展开更多
Soil organic matter content in water-stable aggregates(WSA) in the arid ecosystems(abandoned agricultural lands especially) of China is poorly understood. In this study, we examined the WSA sizes and stability, an...Soil organic matter content in water-stable aggregates(WSA) in the arid ecosystems(abandoned agricultural lands especially) of China is poorly understood. In this study, we examined the WSA sizes and stability, and soil organic carbon(OC) and nitrogen(N) contents in agricultural lands with abandonment ages of 0, 3, 12, 20, 30 and 40 years, respectively, in the Minqin Oasis of Northwest China. The total soil OC and N contents at depths of 0–20, 20–40 and 40–60 cm in abandoned agricultural lands were compared to those in cultivated land(the control). Agricultural land abandonment significantly(P0.25 mm) as the age of agricultural land abandonment increased. The effect of abandonment ages of agricultural lands on MWD was determined by the changes of OC and N accumulation in WSA sizes >2 mm. The total OC and N contents presented a stratification phenomenon across soil depths in this arid ecosystem. That is, both of them decreased significantly at depths of 0–20 and 40–60 cm while increased at the depth of 20–40 cm. The WSA sizes <0.053 mm had the highest soil OC and N contents(accounting for 51.41%–55.59% and 42.61%–48.94% of their total, respectively). Soil OC and N contents in microaggregates(sizes 0.053–0.25 mm) were the dominant factors that influenced the variations of total OC and N contents in abandoned agricultural lands. The results of this study suggested that agricultural land abandonment may result in the recovery of WSA stability and the shifting of soil organic matter from the silt+clay(<0.053 mm) and microaggregate fractions to the macroaggregate fractions. However, agricultural land abandonment did not increase total soil OC and N contents in the short-term.展开更多
Eutrophication and climate change, key environmental concerns, are both linked to the carbon and nitrogen cycles hence the improved understanding of these cycles is essential. Currently, there is no system that simult...Eutrophication and climate change, key environmental concerns, are both linked to the carbon and nitrogen cycles hence the improved understanding of these cycles is essential. Currently, there is no system that simultaneously measures the fluxes of the three key gas phase products of nitrogen and carbon cycling (CO2, CH4 and N2O) in submerged ecosystems with hourly time resolution. A "Lake-in-a-box" (mesocosm) was developed in the laboratory which allowed the monitoring of key components of the carbon and nitrogen cycles within the air, water and sediments. The approach is automated, simple and time efficient and novel in its ability to examine many different carbon and nitrogen compounds in all three physical component of the "lake". Dramatic fluctuations in gaseous flux and the concentrations of overlying water and sedimentary carbon and nitrogen compounds were noted over a three week period. These were split into five distinct phases which were linked to changes in sedimentary N and C cycling. The results highlighted the important of links between the two cycles and supported recent studies showing that estuarine sediments can act as both a source and a sink of nitrogen.展开更多
Generally,the catalytic overpotentials of hydrogen evolution reaction(HER)and oxygen evolution reaction(OER)are unavoidable because of the low charge transfer.In this work,two strategies of alloying of Co with Ni and ...Generally,the catalytic overpotentials of hydrogen evolution reaction(HER)and oxygen evolution reaction(OER)are unavoidable because of the low charge transfer.In this work,two strategies of alloying of Co with Ni and enclosing of electrocatalysts with carbonaceous materials were both used to accelerate the catalytic efficiency of cobalt selenide for water splitting.The nitrogen-doped carbon(NC)layer improves the reaction kinetics by efficient charge transfer.The alloying of metal into composited electrocatalysts can modify the electronic properties of host materials,thereby tuning the adsorption behavior of intermediate and improving the electrocatalytic activity.As expected,Nyquist plots reveal that the charge-transfer resistance(Rct)of nickel cobalt selenide encapsulated into nitrogen-doped carbon layer(CoNiSe/NC-3,Co:Ni=1:1)are just 5 and 9 for HER and OER,respectively,which are much lower than those of CoSe/NC-1(Co:Ni=1:0)(81 and 138)and CoNiSe/NC-3 without NC(CoNiSe-3)(54 and 25).With the high charge transfer and porous structure,CoNiSe/NC-3 shows good performance for both HER and OER.When current density reaches 10 m A cm-2,only 100 and 270 mV overpotentials are required for HER and OER,respectively.With the potential of 1.65 V,full water splitting also can be catalyzed by Co Ni Se/NC-3 with current density of 20 m A cm-2,suggesting that CoNiSe/NC-3 could be used as replacement for noble metal electrocatalysts.展开更多
<span style="font-family:Verdana;">Wind technology is considered to be among the most promising types of renewable energy sources, and due to high oil prices and growing concerns about climate change a...<span style="font-family:Verdana;">Wind technology is considered to be among the most promising types of renewable energy sources, and due to high oil prices and growing concerns about climate change and energy security, it has been the subject of extensive considerations in recent years, including questions related to the relative sus</span><span style="font-family:Verdana;">tainability of electricity production when the manufacturing, assembly,</span><span style="font-family:Verdana;"> transportation and dismantling processes of these facilities are taken into account. The present article evaluates the environmental impacts, carbon emissions and water consumption, derived from the production of electric energy of the Villonaco wind farm, located in Loja</span><span style="font-family:Verdana;">, </span><span style="font-family:""><span style="font-family:Verdana;">Ecuador, during its entire life cycle, using the Life Cycle Analysis for this purpose. Finally, it is concluded that wind energy has greater environmental advantages since it has lower values of carbon and water footprints than other energy sources. Additionally, with the </span><span style="font-family:Verdana;">techniques Cumulative Energy Demand and Energy Return on Investment, sustainability in the production of electricity from wind power in Ecuador is</span><span style="font-family:Verdana;"> demonstrated;and, that due to issues of vulnerability to climate change, the diversification of its energy mix is essential considering the inclusion of non-conventional renewable sources such as solar or wind, this being the only way to reduce both the carbon footprint and the water from the energy supply.</span></span>展开更多
In order to realize industrial production of hydrogen through water splitting,it is essential to develop a cost-efficient and scalable approach to synthesize nonprecious electrocatalysts with sufficiently high activit...In order to realize industrial production of hydrogen through water splitting,it is essential to develop a cost-efficient and scalable approach to synthesize nonprecious electrocatalysts with sufficiently high activity and stability to replace commercial noble-metal-based electrocatalysts.Herein we synthesize cobalt phosphide nanoparticles dispersed within nitrogen-doped carbon nanotube network(CP@NCNT) via scalable spray drying and thermal treatments.As a multifunctional electrocatalyst,the CP@NCNT hybrid delivers outstanding activity for HER(in both acidic and alkaline electrolytes),OER and overall water splitting.Remarkably,it shows an ultra-low overpotental of 94 mV to obtain 10 mA cm-2 in HER.It also demonstrates outstanding activity in overall water splitting,requiring only 1.619 V to deliver 10 mA cm-2with more than 72 h’ long-term stability.The combination of notable performance,multi-functionality and highly scalable spray-drying synthesis method enables this material as a novel and cost-efficient transition metal-based electrocatalysts for overall water splitting.展开更多
Saltmarshes are one of the most productive ecosystems,which contribute significantly to coastal nutrient and carbon budgets.However,limited information is available on soil nutrient and carbon losses via porewater exc...Saltmarshes are one of the most productive ecosystems,which contribute significantly to coastal nutrient and carbon budgets.However,limited information is available on soil nutrient and carbon losses via porewater exchange in saltmarshes.Here,porewater exchange and associated fluxes of nutrients and dissolved inorganic carbon(DIC)in the largest saltmarsh wetland(Chongming Dongtan)in the Changjiang River Estuary were quantified.Porewater exchange rate was estimated to be(37±35)cm/d during December 2017 using a radon(^(222)Rn)mass balance model.The porewater exchange delivered 67 mmol/(m^(2)·d),38 mmol/(m^(2)·d)and 2690 mmol/(m^(2)·d)of dissolved inorganic nitrogen(DIN),dissolved silicon(DSi)and DIC into the coastal waters,respectively.The dominant species of porewater DIN was NH_(4)^(+)(>99%of DIN).However,different with those in other ecosystems,the dissolved inorganic phosphorus(DIP)concentration in saltmarsh porewater was significantly lower than that in surface water,indicating that saltmarshes seem to be a DIP sink in Chongming Dongtan.The porewater-derived DIN,DSi and DIC accounted for 12%,5%and 18%of the riverine inputs,which are important components of coastal nutrient and carbon budgets.Furthermore,porewater-drived nutrients had obviously high N/P ratios(160–3995),indicating that the porewater exchange process may change the nutrient characteristics of the Changjiang River Estuary and further alter the coastal ecological environment.展开更多
Roots are responsible for the uptake of water and nutrients by plants and have the plasticity to dynamically respond to different environmental conditions. However, most land surface models currently prescribe rooting...Roots are responsible for the uptake of water and nutrients by plants and have the plasticity to dynamically respond to different environmental conditions. However, most land surface models currently prescribe rooting profiles as a function only of vegetation type, with no consideration of the surroundings. In this study, a dynamic rooting scheme, which describes root growth as a compromise between water and nitrogen availability, was incorporated into CLM4.5 with carbon-nitrogen (CN) interactions (CLM4.5-CN) to investigate the effects of a dynamic root distribution on eco-hydrological modeling. Two paired numerical simulations were conducted for the Tapajos National Forest km83 (BRSa3) site and the Amazon, one using CLM4.5-CN without the dynamic rooting scheme and the other including the proposed scheme. Simulations for the BRSa3 site showed that inclusion of the dynamic rooting scheme increased the amplitudes and peak values of diurnal gross primary production (GPP) and latent heat flux (LE) for the dry season, and improved the carbon (C) and water cycle modeling by reducing the RMSE of GPP by 0.4 g C m^-2 d^-1, net ecosystem exchange by 1.96 g C m^-2 d^-1, LE by 5.0 W m^-2, and soil moisture by 0.03 m^3 m^-3, at the seasonal scale, compared with eddy flux measurements, while having little impact during the wet season. For the Amazon, regional analysis also revealed that vegetation responses (including GPP and LE) to seasonal drought and the severe drought of 2005 were better captured with the dynamic rooting scheme incorporated.展开更多
Wetland is an important carbon pool,and the degradation of wetlands causes the loss of organic carbon and total nitrogen.This study aims to explore how wetland degradation succession affects soil organic carbon(SOC)an...Wetland is an important carbon pool,and the degradation of wetlands causes the loss of organic carbon and total nitrogen.This study aims to explore how wetland degradation succession affects soil organic carbon(SOC)and total nitrogen(TN)contents in alpine wetland.A field survey of 180 soilsampling profiles was conducted in an alpine wetland that has been classified into three degradation succession stages.The SOC and TN contents of soil layers from 0 to 200 cm depth were studied,including their distribution characteristics and the relationship between microtopography.The results showed that SOC and TN of different degradation succession gradients followed the ranked order of Non Degradation(ND)>Light Degradation(LD)>Heavy Degradation(HD).SWC was positively correlated with SOC and TN(p<0.05).As the degree of degradation succession worsened,SOC and TN became more sensitive to the SWC.Microtopography was closely related to the degree of wetland degradation succession,SWC,SOC and TN,especially in the topsoil(0-30 cm).This result showed that SWC was an important indicator of SOC/TN in alpine wetland.It is highly recommended to strengthen water injection into the wetland as a means of effective restoration to reverse alpine meadow back to marsh alpine wetland.展开更多
Greenhouse gas(GHG)emissions and reactive nitrogen(Nr)releases are central environmental problems,which are closely linked to climate change,environmental ecology and crop production.Sustainable development of agricul...Greenhouse gas(GHG)emissions and reactive nitrogen(Nr)releases are central environmental problems,which are closely linked to climate change,environmental ecology and crop production.Sustainable development of agriculture plays an important role in GHG emissions and Nr loss.The life cycle assessment(LCA)method was used to calculate the product and farm carbon footprints(CFs)and nitrogen footprints(NFs)in rice,wheat and maize production in China based on farm survey data.The results pinpointed that the CFs of rice,wheat and maize were 0.87,0.30 and 0.24 kg/kg.Meanwhile,the computed NFs were 17.11,14.26 and 6.83 g/kg,respectively.Synthetic nitrogen fertilizer applications and methane(CH4)emissions were dominant CF sources,while ammonia(NH3)volatilization was the main NF contributor.Moreover,significant decreases in CF and NF by 20%–54%and 33%–61%,respectively,were found in large-size farms(>20 hm^(2))when compared to small-size farms(<0.7 hm^(2)).Furthermore,the significantly positive relationships between CF and NF indicated the potential for simultaneous mitigation in the regions with high agricultural inputs,like amounts of fertilizer.Based on our results,some effective solutions would be favorable toward mitigating climate change and eutrophication of the major cereal crop production in China,especially optimizing fertilizer use and farm machinery operation efficiencies,as well as developing large-size farms with intensive farming.展开更多
The motivation to calculate this empirical model resulted from often observing—at the time disconcerting—excess dinitrogen gas (N2 concentration > background concentration) in bubble-gas emission samples, collect...The motivation to calculate this empirical model resulted from often observing—at the time disconcerting—excess dinitrogen gas (N2 concentration > background concentration) in bubble-gas emission samples, collected primarily for the purpose of carbon budget research, from Brazilian rivers and reservoirs sampled during roughly 100 field surveys lasting 4 days each on average and executed between years 2000 and 2012. We model the (serendipitously) measured dinitrogen gas above environmental concentration (N2aec) escaping in bubbles from Brazilian rivers as a function of dissolved nitrogen (N) in water. To this model, we mathematically add a pre-existing model of diffusively emitted denitrified dinitrogen (also as a function of dissolved N) from streams in the United States of America (USA). The resulting model predicts denitrified dinitrogen water-air emission from inland waters in the USA, China and Germany.展开更多
Terrestrial ecosystem water use efficiency(WUE)is an important indicator for coupling plant photosynthesis and transpiration,and is also a key factor linking the carbon and water cycles between the land and atmosphere...Terrestrial ecosystem water use efficiency(WUE)is an important indicator for coupling plant photosynthesis and transpiration,and is also a key factor linking the carbon and water cycles between the land and atmosphere.However,under the combination of climate change and human intervention,the change in WUE is still unclear,especially on the Tibetan Plateau(TP).Therefore,satellite remote sensing data and process-based terrestrial biosphere models(TBMs)are used in this study to investigate the spatiotemporal variations of WUE over the TP from 2001 to 2010.Then,the effects of land use and land cover change(LULCC)and CO_(2) fertilization on WUE from 1981-2010 are assessed using TBMs.Results show that climate change is the leading contributor to the change in WUE on the TP,and temperature is the most important factor.LULCC makes a negative contribution to WUE(-20.63%),which is greater than the positive contribution of CO_(2) fertilization(11.65%).In addition,CO_(2) fertilization can effectively improve ecosystem resilience on the TP.On the northwest plateau,the effects of LULCC and CO_(2) fertilization on WUE are more pronounced during the driest years than the annual average.These findings can help researchers understand the response of WUE to climate change and human activity and the coupling of the carbon and water cycles over the TP.展开更多
基金funded by the National Key Research and Development Program of China (2023YFC3206803)the National Natural Science Foundation of China (42271493)
文摘Atmospheric deposition of nitrogen(N)plays a significant role in shaping the structure and functioning of various terrestrial ecosystems worldwide.However,the magnitude of N deposition on grassland ecosystems in Central Asia still remains highly uncertain.In this study,a multi-data approach was adopted to analyze the distribution and amplitude of N deposition effects in Central Asia from 1979 to 2014 using a process-based denitrification decomposition(DNDC)model.Results showed that total vegetation carbon(C)in Central Asia was 0.35(±0.09)Pg C/a and the averaged water stress index(WSI)was 0.20(±0.02)for the whole area.Increasing N deposition led to an increase in the vegetation C of 65.56(±83.03)Tg C and slightly decreased water stress in Central Asia.Findings of this study will expand both our understanding and predictive capacity of C characteristics under future increases in N deposition,and also serve as a valuable reference for decision-making regarding water resources management and climate change mitigation in arid and semi-arid areas globally.
基金Under the auspices of Knowledge Innovation Programs of Chinese Academy of Sciences (No. KZCX2-YW-223)National Natural Science Foundation of China (No. 40803023)+1 种基金Key Program of Natural Science Foundation of Shandong Province(No. ZR2010DZ001)Talents Foundation of Chinese Academy of Sciences (No. AJ0809BX-036)
文摘Stable isotope techniques have been proved useful as tools for studying the carbon (C) and nitrogen (N) biogeochemical cycles of ecosystem. This paper firstly introduced the basic principles and the distribution characteristics of stable isotope, then reviewed the recent advances and applications of stable isotope in the C and N biogeochemical cycles of ecosystem. By applying the 13 C natural abundance technique, ecologists are able to understand the photosynthetic path and CO 2 fixation of plants, the CO 2 exchange and C balance status of ecosystem, the composition, distribution and turnover of soil organic C and the sources of organic matter in food webs, while by using the 13 C labeled technique, the effects of elevated CO 2 on the C processes of ecosystem and the sources and fate of organic matter in ecosystem can be revealed in detail. Differently, by applying the 15 N natural abundance technique, ecologists are able to analyze the biological N 2 -fixation, the N sources of ecosystem, the N transformation processes of ecosystem and the N trophic status in food webs, while by using the 15 N labeled technique, the sources, transformation and fate of N in ecosystem and the effects of N input on the ecosystem can be investigated in depth. The applications of both C and N isotope natural abundance and labeled techniques, combined with the elemental, other isotope ( 34 S) and molecular biomarker information, will be more propitious to the investigation of C and N cycle mechanisms. Finally, this paper concluded the problems existed in current researches, and put forward the perspective of stable isotope techniques in the studies on C and N biogeochemical cycles of ecosystem in the future.
基金supported by the National Key Basic Research Development Program of China (Grant Nos. 2010CB950604 and 2010CB951802)the National Natural Science Foundation of China (Grant No. 40730106, 41075091)
文摘This article reviews recent advances over the past and their relationship to climate change in China. The was 0.19-0.26 Pg C yr-1 for the 1980s and 1990s. 4 years in the study of the carbon-nitrogen cycling net carbon sink in the Chinese terrestrial ecosystem Both natural wetlands and the rice-paddy regions emitted 1.76 Tg and 6.62 Tg of CH4 per year for the periods 1995 2004 and 2005 2009, respectively. China emitted -1.1 Tg N20-N yr-1 to the atmosphere in 2004. Land soil contained -8.3 Pg N. The excess nitrogen stored in farmland of the Yangtze River basin reached 1.51 Tg N and 2.67 Tg N in 1980 and 1990, respectively. The outer Yangtze Estuary served as a moderate or significant sink of atmospheric CO2 except in autumn. Phytoplankton could take up carbon at a rate of 6.4 ×1011 kg yr-1 in the China Sea. The global ocean absorbed anthropogenic CO2 at the rates of 1.64 and 1.73 Pg C yr-1 for two sinmlations in the 1990s. Land net ecosystem production in China would increase until the mid-21st century then would decrease gradually under future climate change scenarios. This research should be strengthened in the future, including collection of more observation data, measurement of the soil organic carbon (SOC) loss and sequestration, evaluation of changes in SOC in deep soil layers, and the impacts of grassland management, carbon-nitrogen coupled effects, and development and improvement of various component models and of the coupled carbon cycle-climate model.
基金kindly supported by the National Key Research and Development Program of China through grant 2016YFA0601000
文摘Southwest China is the primary area for damming rivers to produce hydroelectric energy and store water.River damming has changed hydrodynamic,chemical,and biological processes,which are related to sinks and sources of greenhouse gases and carbon and nitrogen fluxes of different interfaces.Here,I provide an introduction to a river damming-related foundation,the National Key R&D Program of China(2016YTA0601000).Supported by the foundation,we carried out research on multiprocesses/multi-interfaces of carbon and nitrogen biogeochemical cycles in a dammed river system and have produced important results,as presented in this issue of the journal.
基金carried out with funding from the National Key Research and Development Project provided by the Ministry of Science and Technology of China through Grant 2016YFA0601000
文摘The carbon cycle of global inland waters is quantitatively comparable to other components in the global carbon budget. Among inland waters, a significant part is man-made lakes formed by damming rivers. Manmade lakes are undergoing a rapid increase in number and size. Human impacts and frequent algae blooms lead to it necessary to make a better constraint on their carbon cycles. Here, we make a primary estimation on the air–water CO_2 transfer flux through an algae bloom year for a subtropical man-made lake—Hongfeng Lake, Southwest China. To do this a new type of glass bottles was designed for content and isotopic analysis of DIC and other environmental parameters. At the early stage of algae bloom,CO_2 was transferred from the atmosphere to the lake with a net flux of 1.770 g·C·m^(-2). Later, the partial pressure(pCO_2) of the aqueous CO_2 increased rapidly and the lake outgassed to the atmosphere with a net flux of 95.727 g·C·m^(-2). In the remaining days, the lake again took up CO_2 from the atmosphere with a net flux of 14.804 g·C·m^(-2). As a whole, Lake Hongfeng released 4527 t C to the atmosphere, accounting for one-third of the atmosphere/soil CO_2 sequestered by chemical weathering in the whole drainage. With an empirical mode decomposition method, we found air temperature plays a major role in controlling water temperature, aqueous pCO_2 and hence CO_2 flux. This work indicates a necessity to make detailed and comprehensive carbon budgets in man-made lakes.
基金funded by the Special Fund for AgroScientific Research in the Public Interest of China (20110300508, 201203030)supported in partial by the Key Technologies R&D Program of China during the 12th Five-Year Plan period (2012BAD05B05-3, 2013BAD07B11)the International Plant Nutrition Institute, Canada (IPNI China Program: Hunan-17)
文摘In agricultural systems, maintenance of soil organic matter has long been recognized as a strategy to reduce soil degradation. Manure amendments and green manures are management practices that can increase some nutrient contents and improve soil aggregation. We investigated the effects of 28 yr of winter planted green manure on soil aggregate-size distribution and aggregateassociated carbon(C) and nitrogen(N). The study was a randomized completed block design with three replicates. The treatments included rice-rice-fallow, rice-rice-rape, rice-rice-Chinese milk vetch and rice-rice-ryegrass. The experiment was established in 1982 on a silty light clayey paddy soil derived from Quaternary red clay(classified as Fe-Accumuli-Stagnic Anthrosols) with continuous early and late rice. In 2009, soil samples were collected(0-15 cm depth) from the field treatment plots and separated into water-stable aggregates of different sizes(i.e., 〉5, 2-5, 1-2, 0.5-1, 0.25-0.5 and 〈0.25 mm) by wet sieving. The long-term winter planted green manure significantly increased total C and N, and the formation of the 2-5-mm water-stable aggregate fraction. Compared with rice-rice-rape, rice-rice-Chinese milk vetch and rice-rice-ryegrass, the rice-rice-fallow significantly reduced 2-5-mm water-stable aggregates, with a significant redistribution of aggregates into micro-aggregates. Long-term winter planted green manure obviously improved C/N ratio and macro-aggregate-associated C and N. The highest contribution to soil fertility was from macro-aggregates of 2-5 mm in most cases.
基金Supported by European Union[Contract No.CI1*-CT93-0094(DG 12 HSMU)],also by the social development project of Jiangsu Province,China(No.BS99021)
文摘Experimental studies were carried out on the purification of eutrophicTaihu Lake water by dynamic experiment using immobilized nitrogen cycle bacteria(INCB). The results showed that the eutrophic water of Taihu Lake can be purifiedeffectively as it passes through the experimental reactor into which some immobilizednitrogen cycle bacteria were put. The removal efficiencies for Total N (TN), NH4+-Nwith immobilized nitrogen cycle bacteria were 72.4% and 85.6%, respectively. It wasfound that the immobilized nitrogen cycle bacteria also have purificatory effect oneutrophic water of Taihu Lake at winter temperature (7°C), and that the removalmefficiencies for Total N (TN), NH4+-N were 55.6%, and 58.9%, respectively. Theremoval efficiencies for TN and NH4+-N depend on the time the water stays in theexperimental reactor.
文摘This study uses the Life Cycle Analysis (LCA) to evaluate the magnitude of the environmental impact, in terms of global warming potential, and water footprint throughout the 20 years of useful life of a rural electrical energy concession comprised of 120Wp Households photovoltaic systems (HPS) in the isolated communities of San Martin, in the Peruvian Amazon region. On the other hand, due to the particular conditions of the system (installation, operation, maintenance, monthly tariff collection), it is necessary to know its real impact and sustainability;not only through the aforementioned environmental impact indicators, but also by energy intensity values required by the system throughout its life cycle. Therefore, this paper used the Cumulative energy demand (CED) method to determine the amount of energy taken from natural resources for each process involved in the LCA and calculated with this, i.e., the Energy Payback Time (EPBT) of the whole system. Likewise, the HPS has been environmentally compared to other case studies and the Peruvian Energy Mix, revealing a lower impact in the latter case and results within the range for stand-alone systems. Besides, the HPS shows a strong relation between energy production and O&M condition. Additionally, this study allows a further promotion of the use of this type of system in isolated areas, as well as the diversification of electricity generation in Peru.
基金supported by the National Natural Science Foundation of China(No.42007026)the Medical Innovation and Development Project of Lanzhou University(No.lzuyxcx-2022-172)。
文摘The response patterns of microbial functional genes involved in biogeochemical cycles to cadaver decay is a central topic of recent environmental sciences.However,the response mechanisms and pathways of the functional genes associated with the carbon(C)and nitrogen(N)cycling to cadaveric substances such as cadaverine and putrescine remain unclear.This study explored the variation of functional genes associated with C fixation,C degradation and N cycling and their influencing factors under cadaverine,putrescine and mixed treatments.Our results showed only putrescine significantly increased the alpha diversity of C fixation genes,while reducing the alpha diversity of N cycling genes in sediment.For the C cycling,the mixed treatment significantly decreased the total abundance of reductive acetyl-CoA pathway genes(i.e.,acsB and acsE)and lig gene linked to lignin degradation in water,while only significantly increasing the hydroxypropionate-hydroxybutylate cycle(i.e.,accA)gene abundance in sediment.For the N cycling,mixed treatment significantly decreased the abundance of the nitrification(i.e.,amoB),denitrification(i.e.,nirS3)genes in water and the assimilation pathway gene(i.e.,gdhA)in sediment.Environmental factors(i.e.,total carbon and total nitrogen)were all negatively associated with the genes of C and N cycling.Therefore,cadaverine and putrescine exposure may inhibit the pathway in C fixation and N cycling,while promoting C degradation.These findings can offer some new insight for the management of amine pollution caused by animal cadavers.
基金funded by the Science & Technology Pillar Program of Gansu Province (1104FKCH162, 1204FKCH164, 1304FKCH102)the National Natural Science Foundation of China (31560170)
文摘Soil organic matter content in water-stable aggregates(WSA) in the arid ecosystems(abandoned agricultural lands especially) of China is poorly understood. In this study, we examined the WSA sizes and stability, and soil organic carbon(OC) and nitrogen(N) contents in agricultural lands with abandonment ages of 0, 3, 12, 20, 30 and 40 years, respectively, in the Minqin Oasis of Northwest China. The total soil OC and N contents at depths of 0–20, 20–40 and 40–60 cm in abandoned agricultural lands were compared to those in cultivated land(the control). Agricultural land abandonment significantly(P0.25 mm) as the age of agricultural land abandonment increased. The effect of abandonment ages of agricultural lands on MWD was determined by the changes of OC and N accumulation in WSA sizes &gt;2 mm. The total OC and N contents presented a stratification phenomenon across soil depths in this arid ecosystem. That is, both of them decreased significantly at depths of 0–20 and 40–60 cm while increased at the depth of 20–40 cm. The WSA sizes &lt;0.053 mm had the highest soil OC and N contents(accounting for 51.41%–55.59% and 42.61%–48.94% of their total, respectively). Soil OC and N contents in microaggregates(sizes 0.053–0.25 mm) were the dominant factors that influenced the variations of total OC and N contents in abandoned agricultural lands. The results of this study suggested that agricultural land abandonment may result in the recovery of WSA stability and the shifting of soil organic matter from the silt+clay(&lt;0.053 mm) and microaggregate fractions to the macroaggregate fractions. However, agricultural land abandonment did not increase total soil OC and N contents in the short-term.
文摘Eutrophication and climate change, key environmental concerns, are both linked to the carbon and nitrogen cycles hence the improved understanding of these cycles is essential. Currently, there is no system that simultaneously measures the fluxes of the three key gas phase products of nitrogen and carbon cycling (CO2, CH4 and N2O) in submerged ecosystems with hourly time resolution. A "Lake-in-a-box" (mesocosm) was developed in the laboratory which allowed the monitoring of key components of the carbon and nitrogen cycles within the air, water and sediments. The approach is automated, simple and time efficient and novel in its ability to examine many different carbon and nitrogen compounds in all three physical component of the "lake". Dramatic fluctuations in gaseous flux and the concentrations of overlying water and sedimentary carbon and nitrogen compounds were noted over a three week period. These were split into five distinct phases which were linked to changes in sedimentary N and C cycling. The results highlighted the important of links between the two cycles and supported recent studies showing that estuarine sediments can act as both a source and a sink of nitrogen.
基金financial support by the National Natural Science Foundation of China (21605015)the Development Project of Science and Technology of Jilin Province (20170101176JC)+3 种基金the Fundamental Research Funds for the Central Universities (2412017BJ003)the Recruitment Program of Global Youth Experts, the Jilin Provincial Department of Educationthe start-up funds from Northeast Normal Universitythe service support from Analysis and Testing Center of Northeast Normal University
文摘Generally,the catalytic overpotentials of hydrogen evolution reaction(HER)and oxygen evolution reaction(OER)are unavoidable because of the low charge transfer.In this work,two strategies of alloying of Co with Ni and enclosing of electrocatalysts with carbonaceous materials were both used to accelerate the catalytic efficiency of cobalt selenide for water splitting.The nitrogen-doped carbon(NC)layer improves the reaction kinetics by efficient charge transfer.The alloying of metal into composited electrocatalysts can modify the electronic properties of host materials,thereby tuning the adsorption behavior of intermediate and improving the electrocatalytic activity.As expected,Nyquist plots reveal that the charge-transfer resistance(Rct)of nickel cobalt selenide encapsulated into nitrogen-doped carbon layer(CoNiSe/NC-3,Co:Ni=1:1)are just 5 and 9 for HER and OER,respectively,which are much lower than those of CoSe/NC-1(Co:Ni=1:0)(81 and 138)and CoNiSe/NC-3 without NC(CoNiSe-3)(54 and 25).With the high charge transfer and porous structure,CoNiSe/NC-3 shows good performance for both HER and OER.When current density reaches 10 m A cm-2,only 100 and 270 mV overpotentials are required for HER and OER,respectively.With the potential of 1.65 V,full water splitting also can be catalyzed by Co Ni Se/NC-3 with current density of 20 m A cm-2,suggesting that CoNiSe/NC-3 could be used as replacement for noble metal electrocatalysts.
文摘<span style="font-family:Verdana;">Wind technology is considered to be among the most promising types of renewable energy sources, and due to high oil prices and growing concerns about climate change and energy security, it has been the subject of extensive considerations in recent years, including questions related to the relative sus</span><span style="font-family:Verdana;">tainability of electricity production when the manufacturing, assembly,</span><span style="font-family:Verdana;"> transportation and dismantling processes of these facilities are taken into account. The present article evaluates the environmental impacts, carbon emissions and water consumption, derived from the production of electric energy of the Villonaco wind farm, located in Loja</span><span style="font-family:Verdana;">, </span><span style="font-family:""><span style="font-family:Verdana;">Ecuador, during its entire life cycle, using the Life Cycle Analysis for this purpose. Finally, it is concluded that wind energy has greater environmental advantages since it has lower values of carbon and water footprints than other energy sources. Additionally, with the </span><span style="font-family:Verdana;">techniques Cumulative Energy Demand and Energy Return on Investment, sustainability in the production of electricity from wind power in Ecuador is</span><span style="font-family:Verdana;"> demonstrated;and, that due to issues of vulnerability to climate change, the diversification of its energy mix is essential considering the inclusion of non-conventional renewable sources such as solar or wind, this being the only way to reduce both the carbon footprint and the water from the energy supply.</span></span>
基金supported by the University of Electronic Science and Technology of China (Grant No. Y03019023601016208)the National Natural Science Foundation of China (Grant Nos. 21773024, 51372033)National High Technology Research and Development Program of China (Grant No. 2015AA034202)。
文摘In order to realize industrial production of hydrogen through water splitting,it is essential to develop a cost-efficient and scalable approach to synthesize nonprecious electrocatalysts with sufficiently high activity and stability to replace commercial noble-metal-based electrocatalysts.Herein we synthesize cobalt phosphide nanoparticles dispersed within nitrogen-doped carbon nanotube network(CP@NCNT) via scalable spray drying and thermal treatments.As a multifunctional electrocatalyst,the CP@NCNT hybrid delivers outstanding activity for HER(in both acidic and alkaline electrolytes),OER and overall water splitting.Remarkably,it shows an ultra-low overpotental of 94 mV to obtain 10 mA cm-2 in HER.It also demonstrates outstanding activity in overall water splitting,requiring only 1.619 V to deliver 10 mA cm-2with more than 72 h’ long-term stability.The combination of notable performance,multi-functionality and highly scalable spray-drying synthesis method enables this material as a novel and cost-efficient transition metal-based electrocatalysts for overall water splitting.
基金The Natural Science Foundation of Shanghai under contract No.19ZR1415300the Zhejiang Provincial Natural Science Foundation of China under contract No.LQ21D060005the China Postdoctoral Science Foundation under contract No.2020M681931。
文摘Saltmarshes are one of the most productive ecosystems,which contribute significantly to coastal nutrient and carbon budgets.However,limited information is available on soil nutrient and carbon losses via porewater exchange in saltmarshes.Here,porewater exchange and associated fluxes of nutrients and dissolved inorganic carbon(DIC)in the largest saltmarsh wetland(Chongming Dongtan)in the Changjiang River Estuary were quantified.Porewater exchange rate was estimated to be(37±35)cm/d during December 2017 using a radon(^(222)Rn)mass balance model.The porewater exchange delivered 67 mmol/(m^(2)·d),38 mmol/(m^(2)·d)and 2690 mmol/(m^(2)·d)of dissolved inorganic nitrogen(DIN),dissolved silicon(DSi)and DIC into the coastal waters,respectively.The dominant species of porewater DIN was NH_(4)^(+)(>99%of DIN).However,different with those in other ecosystems,the dissolved inorganic phosphorus(DIP)concentration in saltmarsh porewater was significantly lower than that in surface water,indicating that saltmarshes seem to be a DIP sink in Chongming Dongtan.The porewater-derived DIN,DSi and DIC accounted for 12%,5%and 18%of the riverine inputs,which are important components of coastal nutrient and carbon budgets.Furthermore,porewater-drived nutrients had obviously high N/P ratios(160–3995),indicating that the porewater exchange process may change the nutrient characteristics of the Changjiang River Estuary and further alter the coastal ecological environment.
基金supported by the National Natural Science Foundation of China (Grant Nos. 41305066 and 41575096)
文摘Roots are responsible for the uptake of water and nutrients by plants and have the plasticity to dynamically respond to different environmental conditions. However, most land surface models currently prescribe rooting profiles as a function only of vegetation type, with no consideration of the surroundings. In this study, a dynamic rooting scheme, which describes root growth as a compromise between water and nitrogen availability, was incorporated into CLM4.5 with carbon-nitrogen (CN) interactions (CLM4.5-CN) to investigate the effects of a dynamic root distribution on eco-hydrological modeling. Two paired numerical simulations were conducted for the Tapajos National Forest km83 (BRSa3) site and the Amazon, one using CLM4.5-CN without the dynamic rooting scheme and the other including the proposed scheme. Simulations for the BRSa3 site showed that inclusion of the dynamic rooting scheme increased the amplitudes and peak values of diurnal gross primary production (GPP) and latent heat flux (LE) for the dry season, and improved the carbon (C) and water cycle modeling by reducing the RMSE of GPP by 0.4 g C m^-2 d^-1, net ecosystem exchange by 1.96 g C m^-2 d^-1, LE by 5.0 W m^-2, and soil moisture by 0.03 m^3 m^-3, at the seasonal scale, compared with eddy flux measurements, while having little impact during the wet season. For the Amazon, regional analysis also revealed that vegetation responses (including GPP and LE) to seasonal drought and the severe drought of 2005 were better captured with the dynamic rooting scheme incorporated.
基金funded by the Qinghai Science and Technology Department(Grant No.2017-ZJ-799)the Second Tibetan Plateau Scientific Expedition and Research Program(STEP)(Grant No.2019QZKK1002)received form Program for the National Natural Sciences Foundation of China(Grant No.41665008,31872999,41565008,41861049)。
文摘Wetland is an important carbon pool,and the degradation of wetlands causes the loss of organic carbon and total nitrogen.This study aims to explore how wetland degradation succession affects soil organic carbon(SOC)and total nitrogen(TN)contents in alpine wetland.A field survey of 180 soilsampling profiles was conducted in an alpine wetland that has been classified into three degradation succession stages.The SOC and TN contents of soil layers from 0 to 200 cm depth were studied,including their distribution characteristics and the relationship between microtopography.The results showed that SOC and TN of different degradation succession gradients followed the ranked order of Non Degradation(ND)>Light Degradation(LD)>Heavy Degradation(HD).SWC was positively correlated with SOC and TN(p<0.05).As the degree of degradation succession worsened,SOC and TN became more sensitive to the SWC.Microtopography was closely related to the degree of wetland degradation succession,SWC,SOC and TN,especially in the topsoil(0-30 cm).This result showed that SWC was an important indicator of SOC/TN in alpine wetland.It is highly recommended to strengthen water injection into the wetland as a means of effective restoration to reverse alpine meadow back to marsh alpine wetland.
基金supported by the Natural Science Foundation of Zhejiang Province,China(Grant No.LQ21C130002)the Engineering Science and Technology Development Strategy Consulting and Research Project of China(Grant No.Js2019-zd01)the Central Public-Interest Scientific Institution Basal Research Fund of China(Grant No.CPSIBRF-CNRRI-202130)。
文摘Greenhouse gas(GHG)emissions and reactive nitrogen(Nr)releases are central environmental problems,which are closely linked to climate change,environmental ecology and crop production.Sustainable development of agriculture plays an important role in GHG emissions and Nr loss.The life cycle assessment(LCA)method was used to calculate the product and farm carbon footprints(CFs)and nitrogen footprints(NFs)in rice,wheat and maize production in China based on farm survey data.The results pinpointed that the CFs of rice,wheat and maize were 0.87,0.30 and 0.24 kg/kg.Meanwhile,the computed NFs were 17.11,14.26 and 6.83 g/kg,respectively.Synthetic nitrogen fertilizer applications and methane(CH4)emissions were dominant CF sources,while ammonia(NH3)volatilization was the main NF contributor.Moreover,significant decreases in CF and NF by 20%–54%and 33%–61%,respectively,were found in large-size farms(>20 hm^(2))when compared to small-size farms(<0.7 hm^(2)).Furthermore,the significantly positive relationships between CF and NF indicated the potential for simultaneous mitigation in the regions with high agricultural inputs,like amounts of fertilizer.Based on our results,some effective solutions would be favorable toward mitigating climate change and eutrophication of the major cereal crop production in China,especially optimizing fertilizer use and farm machinery operation efficiencies,as well as developing large-size farms with intensive farming.
文摘The motivation to calculate this empirical model resulted from often observing—at the time disconcerting—excess dinitrogen gas (N2 concentration > background concentration) in bubble-gas emission samples, collected primarily for the purpose of carbon budget research, from Brazilian rivers and reservoirs sampled during roughly 100 field surveys lasting 4 days each on average and executed between years 2000 and 2012. We model the (serendipitously) measured dinitrogen gas above environmental concentration (N2aec) escaping in bubbles from Brazilian rivers as a function of dissolved nitrogen (N) in water. To this model, we mathematically add a pre-existing model of diffusively emitted denitrified dinitrogen (also as a function of dissolved N) from streams in the United States of America (USA). The resulting model predicts denitrified dinitrogen water-air emission from inland waters in the USA, China and Germany.
基金supported by the Second Tibetan Plateau Scientific Expedition and Research Program (STEP) (Grant No. 2019QZKK0206)the Strategic Priority Research Program of Chinese Academy of Sciences (Grant No. XDA20100300)+2 种基金the Youth Innovation Promotion Association CAS (2021073)the National Key Scientific and Technological Infrastructure project “Earth System Science Numerical Simulator Facility ” (EarthLab), the Natural Science Foundation of Hunan Province (Grant No. 2020JJ4074)the Open Fund Project of Key Lab of Virtual Geographic Environment (Nanjing Normal University), Ministry of Education (2021VGE04)
文摘Terrestrial ecosystem water use efficiency(WUE)is an important indicator for coupling plant photosynthesis and transpiration,and is also a key factor linking the carbon and water cycles between the land and atmosphere.However,under the combination of climate change and human intervention,the change in WUE is still unclear,especially on the Tibetan Plateau(TP).Therefore,satellite remote sensing data and process-based terrestrial biosphere models(TBMs)are used in this study to investigate the spatiotemporal variations of WUE over the TP from 2001 to 2010.Then,the effects of land use and land cover change(LULCC)and CO_(2) fertilization on WUE from 1981-2010 are assessed using TBMs.Results show that climate change is the leading contributor to the change in WUE on the TP,and temperature is the most important factor.LULCC makes a negative contribution to WUE(-20.63%),which is greater than the positive contribution of CO_(2) fertilization(11.65%).In addition,CO_(2) fertilization can effectively improve ecosystem resilience on the TP.On the northwest plateau,the effects of LULCC and CO_(2) fertilization on WUE are more pronounced during the driest years than the annual average.These findings can help researchers understand the response of WUE to climate change and human activity and the coupling of the carbon and water cycles over the TP.