Space metallurgy is an interdisciplinary field that combines planetary space science and metallurgical engineering.It involves systematic and theoretical engineering technology for utilizing planetary resources in sit...Space metallurgy is an interdisciplinary field that combines planetary space science and metallurgical engineering.It involves systematic and theoretical engineering technology for utilizing planetary resources in situ.However,space metallurgy on the Moon is challenging because the lunar surface has experienced space weathering due to the lack of atmosphere and magnetic field,making the mi-crostructure of lunar soil differ from that of minerals on the Earth.In this study,scanning electron microscopy and transmission electron microscopy analyses were performed on Chang’e-5 powder lunar soil samples.The microstructural characteristics of the lunar soil may drastically change its metallurgical performance.The main special structure of lunar soil minerals include the nanophase iron formed by the impact of micrometeorites,the amorphous layer caused by solar wind injection,and radiation tracks modified by high-energy particle rays inside mineral crystals.The nanophase iron presents a wide distribution,which may have a great impact on the electromagnetic prop-erties of lunar soil.Hydrogen ions injected by solar wind may promote the hydrogen reduction process.The widely distributed amorph-ous layer and impact glass can promote the melting and diffusion process of lunar soil.Therefore,although high-energy events on the lun-ar surface transform the lunar soil,they also increase the chemical activity of the lunar soil.This is a property that earth samples and tradi-tional simulated lunar soil lack.The application of space metallurgy requires comprehensive consideration of the unique physical and chemical properties of lunar soil.展开更多
Reclamation of salt-affected land plays an important role in mitigating the pressure of agricultural land due to competition with industry and construction in China. Drip irrigation was found to be an effective method...Reclamation of salt-affected land plays an important role in mitigating the pressure of agricultural land due to competition with industry and construction in China. Drip irrigation was found to be an effective method to reclaim salt-affected land. In order to improve the effect of reclamation and sustainability of salt-affected land production, a field experiment (with reclaimed 1-3 yr fields) was carried out to investigate changes in soil physical, chemical, and biological properties during the process of reclamation with cropping maize and drip irrigation. Results showed that soil bulk density in 0-20 cm soil layer decreased from 1.71 g·cm-3 in unreclaimed land to 1.44 g ·cm^-3 in reclaimed 3 yr fields, and saturated soil water content of 0-10 cm layer increased correspondingly from 20.3 to 30.2%. Both soil salinity and pH value in 0-40 cm soil layer dropped markedly after reclaiming 3 yr. Soil organic matter content reduced, while total nitrogen, total phosphorus, and total potassium all tended to increase after cropping and drip irrigation. The quantities of bacteria, actinomycete, and fungi in 0-40 cm soil layer all greatly increased with increase of reclaimed years, and they tended to distribute homogeneously in 0-40 cm soil profile. The urease activity and alkaline phosphatase activity in 0-40 cm soil layers were also enhanced, but the sucrase activity was not greatly changed. These results indicated that after crop cultivation and drip irrigation, soil physical environment and nutrients status were both improved. This was benefit for microorganism's activity and plant's growth.展开更多
Spatial distributions of 0-20 cm soil carbon sources/sinks caused by land use changes from the year 1980 to 2000 in an area of 2.97 ~ 106 km2 in eastern China were investigated using a land use dataset from a recent s...Spatial distributions of 0-20 cm soil carbon sources/sinks caused by land use changes from the year 1980 to 2000 in an area of 2.97 ~ 106 km2 in eastern China were investigated using a land use dataset from a recent soil geochemical survey. A map of soil carbon sourcesJsinks has been prepared based on a spatial analysis scheme with GIg. Spatial statistics showed that land use changes had caused 30.7 + 13.64 Tg of surface soil organic carbon loss, which accounts for 0.33% of the total carbon storage of 9.22 Pg. The net effect of the carbon source was estimated to be ~ 71.49 Tg soil carbon decrease and ~ 40.80 Tg increase. Land use changes in Northeast China (NE) have the largest impact on soil organic carbon storage compared with other regions. Paddy fields, which were mainly transformed into dry farmland in NE, and constructed land in other regions, were the largest carbon sources among the land use types. Swamp land in NE was also another large soil carbon source when it was transformed into dry farmland or paddy fields. Dry farmland in the NE region formed the largest soil organic carbon sink, as some were trans- formed into paddy fields, forested land, and other land use types with high SOCD.展开更多
Soil carbon(C) and nitrogen(N) play a crucial role in determining the soil and environmental quality. In this study, we investigated the effects of 26 years(from 1984 to 2010) of farmland management on soil orga...Soil carbon(C) and nitrogen(N) play a crucial role in determining the soil and environmental quality. In this study, we investigated the effects of 26 years(from 1984 to 2010) of farmland management on soil organic carbon(SOC) and soil N in abandoned, wheat(Triticum aestivum L.) non-fertilized, wheat fertilized(mineral fertilizer and organic manure) and alfalfa(Medicago Sativa L.) non-fertilized treatments in a semi-arid region of the Loess Plateau, China. Our results showed that SOC and soil total N contents in the 0–20 cm soil layer increased by 4.29(24.4%) and 1.39 Mg/hm2(100%), respectively, after the conversion of farmland to alfalfa land. Compared to the wheat non-fertilized treatment, SOC and soil total N contents in the 0–20 cm soil layer increased by 4.64(26.4%) and 1.18 Mg/hm2(85.5%), respectively, in the wheat fertilized treatment. In addition, we found that the extents of changes in SOC, soil total N and mineral N depended on soil depth were greater in the upper soil layer(0–30 cm) than in the deeper soil layer(30–100 cm) in the alfalfa land or fertilizer-applied wheat land. Fertilizer applied to winter wheat could increase the accumulation rates of SOC and soil total N. SOC concentration had a significant positive correlation with soil total N concentration. Therefore, this study suggested that farmland management, e.g. the conversion of farmland to alfalfa forage land and fertilizer application, could promote the sequestrations of C and N in soils in semi-arid regions.展开更多
Salt stress has been increasingly constraining crop productivity in arid lands of the world. In our recent study, salt stress was aleviated and crop productivity was improved remarkably by straw layer burial plus plas...Salt stress has been increasingly constraining crop productivity in arid lands of the world. In our recent study, salt stress was aleviated and crop productivity was improved remarkably by straw layer burial plus plastic iflm mulching in a saline soil. However, its impact on the microlfora diversity is not wel documented. Field micro-plot experiments were conducted from 2010 to 2011 using four tilage methods: (i) deep tilage with plastic iflm mulching (CK), (i) straw layer burial at 40 cm (S), (ii) straw layer burial plus surface soil mulching with straw material (S+S), and (iv) plastic iflm mulching plus buried straw layer (P+S). Culturable microbes and predominant bacterial communities were studied; based on 16S rDNA, bacterial com-munity structure and abundance were characterized using denaturing gradient gel electrophoresis (DGGE) and polymerase chain reaction (PCR). Results showed that P+S was the most favorable for culturable bacteria, actinomyces and fungi and induced the most diverse genera of bacteria compared to other tilage methods. Soil temperature had signiifcant positive correlations with the number of bacteria, actinomyces and fungi (P〈0.01). However, soil water was poorly correlated with any of the microbes. Salt content had a signiifcant negative correlation with the number of microbers, especialy for bacteria and fungi (P〈0.01). DGGE analysis showed that the P+S exhibited the highest diversity of bacteria with 20 visible bands folowed by S+S, S and CK. Moreover, P+S had the highest similarity (68%) of bacterial communities with CK. The major bacterial genera in al soil samples wereFirmicutes,Proteobacteria andActinobacteria. Given the considerable increase in microbial growth, the combined use of straw layer burial and plastic iflm mulching could be a practical option for aleviating salt stress effects on soil microbial community and thereby improving crop production in arid saline soils.展开更多
The effects of film mulching of millet on soil water content were studied in semi-arid areas in the Loess Plateau of South Ningxia, China. Different mulching methods including water micro-collecting farming (WF), wa...The effects of film mulching of millet on soil water content were studied in semi-arid areas in the Loess Plateau of South Ningxia, China. Different mulching methods including water micro-collecting farming (WF), water micro-collecting farming in winter fallow (WW), hole seeding on film (HF), hole seeding on film in winter fallow (HW) were compared to determine the effects of mulching methods on soil water collecting and conservation during millet growth periods of 2003-2004, as well as the variation tendency of water content after rainfall, output of millet and water use efficiency (WUE). The experimental results in the two successive years indicated that water micro-collecting farming had a better function of collecting water after rainfall, and side infiltrated water was stored under the ridges and the top layer 0-40 cm soil water changes were great. WF had obvious role in water collection and preservation of soil moisture. It effectively improved the water supply capacity by about 19.05% in the end of growth seasons. The storage of HW and WW increased by 24.9 and 7.1 mm compared with CK, and output of yield were obviously increased. Film mulching increased the yield of millet and enhanced water use efficiency (WUE). During different growth periods, WF exhibited better water storage function with lower water consumption, and demonstrated optimal social and ecological benefits.展开更多
Drying of soil was linearly related to time, soil volume decreased and ratio of air within the soils increased. Respiration was related with decreasing humidity, storage of CO2 in soil water results in RQ < 0.5 in ...Drying of soil was linearly related to time, soil volume decreased and ratio of air within the soils increased. Respiration was related with decreasing humidity, storage of CO2 in soil water results in RQ < 0.5 in the larger soil items at least for a while. Rate of drying decreased in the second part of the process. RQ increased as the CO2 stored was aerated when its solvent-water evaporated and access of air into the soil increased;eventually RQ = 1.0 in the last days of the experiment. Respiration of the experimental soil stopped when GWC reached 0.15. ΣRQ for the whole process is about 0.7, a bit higher in experiments with less soil suggesting less anoxia.展开更多
The Qinghai-Tibet Plateau(QTP)has experienced rapid environmental changes,including climate warming and wetting,since the 1980s.These environmental changes significantly impact the shallow soil hydrothermal conditions...The Qinghai-Tibet Plateau(QTP)has experienced rapid environmental changes,including climate warming and wetting,since the 1980s.These environmental changes significantly impact the shallow soil hydrothermal conditions,which have key roles in land-atmosphere feedback and ecosystem functions.However,the spatial variations and responses of soil hydrothermal conditions to environmental changes over the QTP with permafrost(PF)and seasonal frost(SF)remain unclear.In this study,we investigated the spatial variations in soil temperature(ST)and soil moisture(SM)changes over the QTP from 2000 to 2020 using 99 in-situ sites with observations at 4 depths(i.e.10,40,100 and 200 cm).The main environmental controlling factors were further identified using a calibrated statistical model.Results showed that significant(p<0.05)soil warming occurred at multiple soil layers during 2000-2020 with a wide variation(i.e.0.033-0.039℃ per year on average),whereas the warming rates at PF sites were two times greater than those at SF sites.In addition,the soil wetting rate was high over the SF region,whereas the soil wetting rate was low over the PF region.Aside from air temperature,changes in thawing degree days and solar radiation(Srad)contributed most to soil warming in the PF region,whereas changes in rainfall,Srad and evaporation(EVA)have been identified as the key factors in the SF region.As for soil wetting,changes in snowfall,freezing degree days and vegetation have noticeable nonlinear effects over the PF region,whereas changes in EVA,Srad and rainfall highlighted distinct linear and nonlinear effects in the SF region.These findings enhance our understanding of the hydrothermal impacts of future environmental changes over the QTP.展开更多
The transport mechanisms of water,heat,and salt in unsaturated frozen soil,as well as its response to future climate change are in urgent need of study.In this study,western Jilin Province in north-eastern China was s...The transport mechanisms of water,heat,and salt in unsaturated frozen soil,as well as its response to future climate change are in urgent need of study.In this study,western Jilin Province in north-eastern China was studied to produce a model of coupled water-heat-salt in unsaturated frozen soil using CoupModel.The water,heat,and salt dynamics of unsaturated frozen soil under three representative concentration pathway(RCP)scenarios were simulated to analyze the effects of future climate change on unsaturated frozen soil.The results show that water,heat,and salt migration are tightly coupled,and the soil salt concentration in the surface layer(10 cm)exhibits explosive growth after freezing and thawing.The future(2020–2099)meteorological factors in the study area were predicted using the Statistical Downscaling Model(SDSM).For RCP2.6,RCP4.5,and RCP8.5 scenarios,future temperatures during the freeze–thaw period increased by 2.68°C,3.18°C,and 4.28°C,respectively;precipitation increased by 30.28 mm,28.41 mm,and 32.17 mm,respectively;and evaporation increased by 93.57 mm,106.95 mm,and 130.57 mm,respectively.Climate change will shorten the freeze–thaw period,advance the soil melting time from April to March,and enhance water and salt transport.Compared to the baseline period(1961–2005),future soil salt concentrations at 10 cm increased by 1547.54 mg/L,1762.86 mg/L,and 1713.66 mg/L under RCP2.6,RCP4.5,and RCP8.5,respectively.The explosive salt accumulation is more obvious.Effective measures should be taken to prevent the salinization of unsaturated frozen soils and address climate change.展开更多
Soil carbon sequestration and potential has been a focal issue in global carbon research. Under the background of global change, the estimation of the size as well as its change of soil organic carbon(SOC) storage i...Soil carbon sequestration and potential has been a focal issue in global carbon research. Under the background of global change, the estimation of the size as well as its change of soil organic carbon(SOC) storage is of great importance. Based on soil data from the second national soil survey and field survey during 2011–2012, by using the regression method between sampling soil data and remote sensing data, this paper aimed to investigate spatial distribution and changes of topsoil(0–20 cm) organic carbon storage in grasslands of Inner Mongolia between the 1980 s and 2010 s. The results showed that:(1) the SOC storage in grasslands of Inner Mongolia between the 1980 s and 2010 s was estimated to be 2.05 and 2.17 Pg C, with an average density of 3.48 and 3.69 kg C·m–2, respectively. The SOC storage was mainly distributed in the typical steppe and meadow steppe, which accounted for over 98% of the total SOC storage. The spatial distribution showed a decreased trend from the meadow steppe, typical steppe to the desert steppe, corresponding to the temperature and precipitation gradient.(2) SOC changes during 1982–2012 were estimated to be 0.12 Pg C, at 7.00 g C·m–2·yr–1, which didn't show a significant change, indicating that SOC storage in grasslands of Inner Mongolia remained relatively stable over this period. However, topsoil organic carbon showed different trends of carbon source/sink during the past three decades. Meadow steppe and typical steppe had sequestered 0.15 and 0.03 Pg C, respectively, served as a carbon sink; while desert steppe lost 0.06 Pg C, served as a carbon source. It appears that SOC storage in grassland ecosystem may respond differently to climate change, related to vegetation type, regional climate type and grazing intensity. These results might give advice to decision makers on adopting suitable countermeasures for sustainable grassland utilization and protection.展开更多
Lunar soil preserves numerous fragments of meteorites impacting on the Moon,providing a unique opportunity to investigate the distribution of the types of projectiles over billions of years.Here we report the first di...Lunar soil preserves numerous fragments of meteorites impacting on the Moon,providing a unique opportunity to investigate the distribution of the types of projectiles over billions of years.Here we report the first discovery of an iron meteorite fragment from the Chang’e-5 lunar soil,which consists mainly of martensite(quenched from taenite),kamacite,and schreibersite,with a trace of pentlandite.The meteorite fragment is Ni-and P-rich,S-poor,and based on its mineral chemistry and bulk composition,can be classified into the IID-group,a rare and carbonaceous group of iron meteorite originating in the outer Solar System.This meteorite fragment experienced only limited partial melting followed by fast cooling,suggestive of efficient preservation of intact remnants of iron meteorites impacting on the porous lunar regolith.Alternatively,it is a relic of a low-velocity impact of submillimeter-sized metal grains originated from an IID-like iron meteorite.Our observations demonstrate that it is feasible to achieve the type distribution of meteorites impacting on the Moon via systematically analyzing a large number of metal grains separated from lunar soils,thus shedding light on the dynamic evolution of the Solar System.展开更多
Aims The tree legume Acacia dealbata Link is an aggressive Australian invader that severely affects abiotic and biotic compartments of eco-systems worldwide.This invasive species outcompetes native plant communities t...Aims The tree legume Acacia dealbata Link is an aggressive Australian invader that severely affects abiotic and biotic compartments of eco-systems worldwide.This invasive species outcompetes native plant communities through direct competition,changes in microhabitat and soil properties under the canopy and the release of allelopathic compounds.However,these effects are usually studied separately and under controlled conditions.The objective of this study was to evaluate the combined effect of these modifications exerted by A.dealbata on the establishment of native and invasive species in the field.Methods A full factorial experiment was performed in order to test the com-bined effect of microhabitat,soil type and allelopathy on the establish-ment of the invasive A.dealbata and three native species in the field(North-West Spain).We sowed seeds of native or invasive species in pots with different soil type(soil collected under A.dealbata or Pinus pinaster),allelopathy status(soil treated or untreated with activated car-bon)and microhabitat(under the canopy of A.dealbata or P.pinaster).The number and total biomass of established plants were evaluated after 8 months.Soil abiotic properties were determined in all soils.Important Findings The establishment of native and invasive species was signifi-cantly affected by the microhabitat,with a higher number of seedlings under the native forest(P.pinaster).The establishment of A.dealbata seedlings was also significantly promoted by its own soil.A negligible effect of allelopathy was detected on the establishment and growth of both invasive and native species.We conclude that(i)the main factor affecting seedling establish-ment was microhabitat rather than changes in soil properties or allelopathy,(ii)soil modifications by A.dealbata promote the establishment of its own seedlings,contributing to the progress of invasion and(iii)allelochemicals released by A.dealbata do not seem to play a key role for the establishment of native and invasive plants under field conditions in the European non-native range.展开更多
The aim of this experiment was to determine the impacts of climate change on soil profile concentrations and diffusion effluxes of methane in a rice-wheat annual rotation ecosystem in Southeastern China. We initiated ...The aim of this experiment was to determine the impacts of climate change on soil profile concentrations and diffusion effluxes of methane in a rice-wheat annual rotation ecosystem in Southeastern China. We initiated a field experiment with four treatments:ambient conditions(CKs), CO2 concentration elevated to - 500 μmol/mol(FACE),temperature elevated by ca. 2°C(T) and combined elevation of CO2 concentration and temperature(FACE + T). A multilevel sampling probe was designed to collect the soil gas at four different depths, namely, 7 cm, 15 cm, 30 cm and 50 cm. Methane concentrations were higher during the rice season and decreased with depth, while lower during the wheat season and increased with depth. Compared to CK, mean methane concentration was increased by 42%, 57% and 71% under the FACE, FACE + T and T treatments, respectively, at the 7 cm depth during the rice season(p 〈 0.05). Mean methane diffusion effluxes to the 7 cm depth were positive in the rice season and negative in the wheat season, resulting in the paddy field being a source and weak sink, respectively. Moreover, mean methane diffusion effluxes in the rice season were 0.94, 1.19 and 1.42 mg C/(m^2·hr) in the FACE,FACE + T and T treatments, respectively, being clearly higher than that in the CK. The results indicated that elevated atmospheric CO2 concentration and temperature could significantly increase soil profile methane concentrations and their effluxes from a rice-wheat field annual rotation ecosystem(p 〈 0.05).展开更多
Acidobacteria is one of the most dominant and abundant phyla in soil,and was believed to have a wide range of metabolic and genetic functions. Relatively little is known about its community structure and elevational d...Acidobacteria is one of the most dominant and abundant phyla in soil,and was believed to have a wide range of metabolic and genetic functions. Relatively little is known about its community structure and elevational diversity patterns. We selected four elevation gradients from 1000 to 2800 m with typical vegetation types of the northern slope of Shennongjia Mountain in central China. The vegetation types were evergreen broadleaved forest,deciduous broadleaved forest,coniferous forest and sub-alpine shrubs. We analyzed the soil acidobacterial community composition,elevational patterns and the relationship between Acidobacteria subdivisions and soil enzyme activities by using the 16 S rRNA meta-sequencing technique and multivariate statistical analysis. The result found that 19 known subdivisions as well as an unclassified phylotype were presented in these forest sites,and Subdivision 6 has the highest number of detectable operational taxonomic units(OTUs). A significant single peak distribution pattern(P 〈 0.05) between the OTU number and the elevation was observed. The Jaccard and Bray–Curtis index analysis showed that the soil Acidobacteria compositional similarity significantly decreased(P 〈 0.01) with the increase in elevation distance. Mantel test analysis showed the most of the soil Acidobacteria subdivisions had the significant relationship(P 〈 0.01) with different soil enzymes. Therefore,soil Acidobacteria may be involved in different ecosystem functions in global elemental cycles. Partial Mantel tests and CCA analysis showed that soil pH,soil temperature and plant diversity may be the key factors in shaping the soil Acidobacterial community structure.展开更多
基金The authors thank CNSA for providing access to the lunar sample CE5C0200YJFM00302.The authors also would like to thank funding support from the Strategic Priority Research Program of the Chinese Academy of Sciences(No.XDB 41000000)the National Natural Science Foundation of China(Nos.42273042 and 41931077)+4 种基金the Youth Innovation Promotion Association Chinese Academy of Sciences(No.2020395)Key Research Program of Frontier Sciences,Chinese Academy of Sciences(Nos.ZDBS-SSW-JSC007-10 and QYZDY-SSW-DQC028)the Young and Middleaged Academic Technology Leader Reserve Talent Project of Yunnan Province(No.2018HB009)the Science Fund for Outstanding Youth of Yunnan Province(No.202101 AV070007)the"From 0 to 1"Original Exploration Cultivation Project,Institute of Geochemistry,Chinese Academy of Sciences(No.DHSZZ2023-3).
文摘Space metallurgy is an interdisciplinary field that combines planetary space science and metallurgical engineering.It involves systematic and theoretical engineering technology for utilizing planetary resources in situ.However,space metallurgy on the Moon is challenging because the lunar surface has experienced space weathering due to the lack of atmosphere and magnetic field,making the mi-crostructure of lunar soil differ from that of minerals on the Earth.In this study,scanning electron microscopy and transmission electron microscopy analyses were performed on Chang’e-5 powder lunar soil samples.The microstructural characteristics of the lunar soil may drastically change its metallurgical performance.The main special structure of lunar soil minerals include the nanophase iron formed by the impact of micrometeorites,the amorphous layer caused by solar wind injection,and radiation tracks modified by high-energy particle rays inside mineral crystals.The nanophase iron presents a wide distribution,which may have a great impact on the electromagnetic prop-erties of lunar soil.Hydrogen ions injected by solar wind may promote the hydrogen reduction process.The widely distributed amorph-ous layer and impact glass can promote the melting and diffusion process of lunar soil.Therefore,although high-energy events on the lun-ar surface transform the lunar soil,they also increase the chemical activity of the lunar soil.This is a property that earth samples and tradi-tional simulated lunar soil lack.The application of space metallurgy requires comprehensive consideration of the unique physical and chemical properties of lunar soil.
基金supported by the Chinese Academy of Sciences Action Plan for the Development of Western China (KZCX2-XB2-13)the Chinese Academy of Sciences Knowledge Innovation Project(KSCX2-YW-N-080)the Project for 100 Outstanding Young Scientists supported by Chinese Academy of Sciences
文摘Reclamation of salt-affected land plays an important role in mitigating the pressure of agricultural land due to competition with industry and construction in China. Drip irrigation was found to be an effective method to reclaim salt-affected land. In order to improve the effect of reclamation and sustainability of salt-affected land production, a field experiment (with reclaimed 1-3 yr fields) was carried out to investigate changes in soil physical, chemical, and biological properties during the process of reclamation with cropping maize and drip irrigation. Results showed that soil bulk density in 0-20 cm soil layer decreased from 1.71 g·cm-3 in unreclaimed land to 1.44 g ·cm^-3 in reclaimed 3 yr fields, and saturated soil water content of 0-10 cm layer increased correspondingly from 20.3 to 30.2%. Both soil salinity and pH value in 0-40 cm soil layer dropped markedly after reclaiming 3 yr. Soil organic matter content reduced, while total nitrogen, total phosphorus, and total potassium all tended to increase after cropping and drip irrigation. The quantities of bacteria, actinomycete, and fungi in 0-40 cm soil layer all greatly increased with increase of reclaimed years, and they tended to distribute homogeneously in 0-40 cm soil profile. The urease activity and alkaline phosphatase activity in 0-40 cm soil layers were also enhanced, but the sucrase activity was not greatly changed. These results indicated that after crop cultivation and drip irrigation, soil physical environment and nutrients status were both improved. This was benefit for microorganism's activity and plant's growth.
基金financially supported by the Geological Survey Project of CGS(12120113000400 and DD20160323)the Fundamental Research Funds for the Central Universities (2652015055)
文摘Spatial distributions of 0-20 cm soil carbon sources/sinks caused by land use changes from the year 1980 to 2000 in an area of 2.97 ~ 106 km2 in eastern China were investigated using a land use dataset from a recent soil geochemical survey. A map of soil carbon sourcesJsinks has been prepared based on a spatial analysis scheme with GIg. Spatial statistics showed that land use changes had caused 30.7 + 13.64 Tg of surface soil organic carbon loss, which accounts for 0.33% of the total carbon storage of 9.22 Pg. The net effect of the carbon source was estimated to be ~ 71.49 Tg soil carbon decrease and ~ 40.80 Tg increase. Land use changes in Northeast China (NE) have the largest impact on soil organic carbon storage compared with other regions. Paddy fields, which were mainly transformed into dry farmland in NE, and constructed land in other regions, were the largest carbon sources among the land use types. Swamp land in NE was also another large soil carbon source when it was transformed into dry farmland or paddy fields. Dry farmland in the NE region formed the largest soil organic carbon sink, as some were trans- formed into paddy fields, forested land, and other land use types with high SOCD.
基金funded by the Fok Ying-Tong Education Foundation for Young Teachers in the Higher Education Institutions of China (131025)the Natural Science Foundation of Shaanxi Province (2014KJXX-52)
文摘Soil carbon(C) and nitrogen(N) play a crucial role in determining the soil and environmental quality. In this study, we investigated the effects of 26 years(from 1984 to 2010) of farmland management on soil organic carbon(SOC) and soil N in abandoned, wheat(Triticum aestivum L.) non-fertilized, wheat fertilized(mineral fertilizer and organic manure) and alfalfa(Medicago Sativa L.) non-fertilized treatments in a semi-arid region of the Loess Plateau, China. Our results showed that SOC and soil total N contents in the 0–20 cm soil layer increased by 4.29(24.4%) and 1.39 Mg/hm2(100%), respectively, after the conversion of farmland to alfalfa land. Compared to the wheat non-fertilized treatment, SOC and soil total N contents in the 0–20 cm soil layer increased by 4.64(26.4%) and 1.18 Mg/hm2(85.5%), respectively, in the wheat fertilized treatment. In addition, we found that the extents of changes in SOC, soil total N and mineral N depended on soil depth were greater in the upper soil layer(0–30 cm) than in the deeper soil layer(30–100 cm) in the alfalfa land or fertilizer-applied wheat land. Fertilizer applied to winter wheat could increase the accumulation rates of SOC and soil total N. SOC concentration had a significant positive correlation with soil total N concentration. Therefore, this study suggested that farmland management, e.g. the conversion of farmland to alfalfa forage land and fertilizer application, could promote the sequestrations of C and N in soils in semi-arid regions.
基金funded by the National Natural Science Foundation of China(31471455,31000692 and 31070002)the Fundamental Research Funds for National Public Research Institutions,China(ZYQHS2015-25)the Beijing Natural Science Foundation,China(5152017)
文摘Salt stress has been increasingly constraining crop productivity in arid lands of the world. In our recent study, salt stress was aleviated and crop productivity was improved remarkably by straw layer burial plus plastic iflm mulching in a saline soil. However, its impact on the microlfora diversity is not wel documented. Field micro-plot experiments were conducted from 2010 to 2011 using four tilage methods: (i) deep tilage with plastic iflm mulching (CK), (i) straw layer burial at 40 cm (S), (ii) straw layer burial plus surface soil mulching with straw material (S+S), and (iv) plastic iflm mulching plus buried straw layer (P+S). Culturable microbes and predominant bacterial communities were studied; based on 16S rDNA, bacterial com-munity structure and abundance were characterized using denaturing gradient gel electrophoresis (DGGE) and polymerase chain reaction (PCR). Results showed that P+S was the most favorable for culturable bacteria, actinomyces and fungi and induced the most diverse genera of bacteria compared to other tilage methods. Soil temperature had signiifcant positive correlations with the number of bacteria, actinomyces and fungi (P〈0.01). However, soil water was poorly correlated with any of the microbes. Salt content had a signiifcant negative correlation with the number of microbers, especialy for bacteria and fungi (P〈0.01). DGGE analysis showed that the P+S exhibited the highest diversity of bacteria with 20 visible bands folowed by S+S, S and CK. Moreover, P+S had the highest similarity (68%) of bacterial communities with CK. The major bacterial genera in al soil samples wereFirmicutes,Proteobacteria andActinobacteria. Given the considerable increase in microbial growth, the combined use of straw layer burial and plastic iflm mulching could be a practical option for aleviating salt stress effects on soil microbial community and thereby improving crop production in arid saline soils.
基金This study was supported by a key grant from China National 863 High Technology Program(2002AA2Z4021—2)the National Natural Science Foundation of China(30070439,303002 1 3) the Young Key Scholar Program of Northwest A & F University
文摘The effects of film mulching of millet on soil water content were studied in semi-arid areas in the Loess Plateau of South Ningxia, China. Different mulching methods including water micro-collecting farming (WF), water micro-collecting farming in winter fallow (WW), hole seeding on film (HF), hole seeding on film in winter fallow (HW) were compared to determine the effects of mulching methods on soil water collecting and conservation during millet growth periods of 2003-2004, as well as the variation tendency of water content after rainfall, output of millet and water use efficiency (WUE). The experimental results in the two successive years indicated that water micro-collecting farming had a better function of collecting water after rainfall, and side infiltrated water was stored under the ridges and the top layer 0-40 cm soil water changes were great. WF had obvious role in water collection and preservation of soil moisture. It effectively improved the water supply capacity by about 19.05% in the end of growth seasons. The storage of HW and WW increased by 24.9 and 7.1 mm compared with CK, and output of yield were obviously increased. Film mulching increased the yield of millet and enhanced water use efficiency (WUE). During different growth periods, WF exhibited better water storage function with lower water consumption, and demonstrated optimal social and ecological benefits.
文摘Drying of soil was linearly related to time, soil volume decreased and ratio of air within the soils increased. Respiration was related with decreasing humidity, storage of CO2 in soil water results in RQ < 0.5 in the larger soil items at least for a while. Rate of drying decreased in the second part of the process. RQ increased as the CO2 stored was aerated when its solvent-water evaporated and access of air into the soil increased;eventually RQ = 1.0 in the last days of the experiment. Respiration of the experimental soil stopped when GWC reached 0.15. ΣRQ for the whole process is about 0.7, a bit higher in experiments with less soil suggesting less anoxia.
基金This study is funded by the National Natural Science Foundation of China(U2268216,42372334)the Science and Technology Research and Development Program of the Qinghai-Tibet Group Corporation(QZ2022-G05)the Youth Innovation Promotion Association of the Chinese Academy of Sciences(2020421).We gratefully acknowledge the anonymous reviewers and editors for their constructive comments that substantially improved the manuscript.
文摘The Qinghai-Tibet Plateau(QTP)has experienced rapid environmental changes,including climate warming and wetting,since the 1980s.These environmental changes significantly impact the shallow soil hydrothermal conditions,which have key roles in land-atmosphere feedback and ecosystem functions.However,the spatial variations and responses of soil hydrothermal conditions to environmental changes over the QTP with permafrost(PF)and seasonal frost(SF)remain unclear.In this study,we investigated the spatial variations in soil temperature(ST)and soil moisture(SM)changes over the QTP from 2000 to 2020 using 99 in-situ sites with observations at 4 depths(i.e.10,40,100 and 200 cm).The main environmental controlling factors were further identified using a calibrated statistical model.Results showed that significant(p<0.05)soil warming occurred at multiple soil layers during 2000-2020 with a wide variation(i.e.0.033-0.039℃ per year on average),whereas the warming rates at PF sites were two times greater than those at SF sites.In addition,the soil wetting rate was high over the SF region,whereas the soil wetting rate was low over the PF region.Aside from air temperature,changes in thawing degree days and solar radiation(Srad)contributed most to soil warming in the PF region,whereas changes in rainfall,Srad and evaporation(EVA)have been identified as the key factors in the SF region.As for soil wetting,changes in snowfall,freezing degree days and vegetation have noticeable nonlinear effects over the PF region,whereas changes in EVA,Srad and rainfall highlighted distinct linear and nonlinear effects in the SF region.These findings enhance our understanding of the hydrothermal impacts of future environmental changes over the QTP.
基金This research was funded by the National Key R&D Program of China(Grant No.2018YFC1800400)。
文摘The transport mechanisms of water,heat,and salt in unsaturated frozen soil,as well as its response to future climate change are in urgent need of study.In this study,western Jilin Province in north-eastern China was studied to produce a model of coupled water-heat-salt in unsaturated frozen soil using CoupModel.The water,heat,and salt dynamics of unsaturated frozen soil under three representative concentration pathway(RCP)scenarios were simulated to analyze the effects of future climate change on unsaturated frozen soil.The results show that water,heat,and salt migration are tightly coupled,and the soil salt concentration in the surface layer(10 cm)exhibits explosive growth after freezing and thawing.The future(2020–2099)meteorological factors in the study area were predicted using the Statistical Downscaling Model(SDSM).For RCP2.6,RCP4.5,and RCP8.5 scenarios,future temperatures during the freeze–thaw period increased by 2.68°C,3.18°C,and 4.28°C,respectively;precipitation increased by 30.28 mm,28.41 mm,and 32.17 mm,respectively;and evaporation increased by 93.57 mm,106.95 mm,and 130.57 mm,respectively.Climate change will shorten the freeze–thaw period,advance the soil melting time from April to March,and enhance water and salt transport.Compared to the baseline period(1961–2005),future soil salt concentrations at 10 cm increased by 1547.54 mg/L,1762.86 mg/L,and 1713.66 mg/L under RCP2.6,RCP4.5,and RCP8.5,respectively.The explosive salt accumulation is more obvious.Effective measures should be taken to prevent the salinization of unsaturated frozen soils and address climate change.
基金The National Basic Research Program of China(973 Program),No.2011CB403206No.2012CB416906National Key Technology R&D Program,No.2013BAC03B04
文摘Soil carbon sequestration and potential has been a focal issue in global carbon research. Under the background of global change, the estimation of the size as well as its change of soil organic carbon(SOC) storage is of great importance. Based on soil data from the second national soil survey and field survey during 2011–2012, by using the regression method between sampling soil data and remote sensing data, this paper aimed to investigate spatial distribution and changes of topsoil(0–20 cm) organic carbon storage in grasslands of Inner Mongolia between the 1980 s and 2010 s. The results showed that:(1) the SOC storage in grasslands of Inner Mongolia between the 1980 s and 2010 s was estimated to be 2.05 and 2.17 Pg C, with an average density of 3.48 and 3.69 kg C·m–2, respectively. The SOC storage was mainly distributed in the typical steppe and meadow steppe, which accounted for over 98% of the total SOC storage. The spatial distribution showed a decreased trend from the meadow steppe, typical steppe to the desert steppe, corresponding to the temperature and precipitation gradient.(2) SOC changes during 1982–2012 were estimated to be 0.12 Pg C, at 7.00 g C·m–2·yr–1, which didn't show a significant change, indicating that SOC storage in grasslands of Inner Mongolia remained relatively stable over this period. However, topsoil organic carbon showed different trends of carbon source/sink during the past three decades. Meadow steppe and typical steppe had sequestered 0.15 and 0.03 Pg C, respectively, served as a carbon sink; while desert steppe lost 0.06 Pg C, served as a carbon source. It appears that SOC storage in grassland ecosystem may respond differently to climate change, related to vegetation type, regional climate type and grazing intensity. These results might give advice to decision makers on adopting suitable countermeasures for sustainable grassland utilization and protection.
基金supported by the National Natural Science Foundation of China(42230206,42241152,and 42103035)the Key Research Program of Frontier Sciences,Chinese Academy of Sciences(QYZDJ-SSW-DQC001).
文摘Lunar soil preserves numerous fragments of meteorites impacting on the Moon,providing a unique opportunity to investigate the distribution of the types of projectiles over billions of years.Here we report the first discovery of an iron meteorite fragment from the Chang’e-5 lunar soil,which consists mainly of martensite(quenched from taenite),kamacite,and schreibersite,with a trace of pentlandite.The meteorite fragment is Ni-and P-rich,S-poor,and based on its mineral chemistry and bulk composition,can be classified into the IID-group,a rare and carbonaceous group of iron meteorite originating in the outer Solar System.This meteorite fragment experienced only limited partial melting followed by fast cooling,suggestive of efficient preservation of intact remnants of iron meteorites impacting on the porous lunar regolith.Alternatively,it is a relic of a low-velocity impact of submillimeter-sized metal grains originated from an IID-like iron meteorite.Our observations demonstrate that it is feasible to achieve the type distribution of meteorites impacting on the Moon via systematically analyzing a large number of metal grains separated from lunar soils,thus shedding light on the dynamic evolution of the Solar System.
基金P.L.is supported by a post-doctoral grant(SFRH/BPD/88504/2012)from the Fundação para a Ciência e a Tecnologia(Portugal)(FCT)and the European Social FundS.R.-E has an Investigador IF Development Grant(IF/00462/2013)from the FCT and the European Social Fund.
文摘Aims The tree legume Acacia dealbata Link is an aggressive Australian invader that severely affects abiotic and biotic compartments of eco-systems worldwide.This invasive species outcompetes native plant communities through direct competition,changes in microhabitat and soil properties under the canopy and the release of allelopathic compounds.However,these effects are usually studied separately and under controlled conditions.The objective of this study was to evaluate the combined effect of these modifications exerted by A.dealbata on the establishment of native and invasive species in the field.Methods A full factorial experiment was performed in order to test the com-bined effect of microhabitat,soil type and allelopathy on the establish-ment of the invasive A.dealbata and three native species in the field(North-West Spain).We sowed seeds of native or invasive species in pots with different soil type(soil collected under A.dealbata or Pinus pinaster),allelopathy status(soil treated or untreated with activated car-bon)and microhabitat(under the canopy of A.dealbata or P.pinaster).The number and total biomass of established plants were evaluated after 8 months.Soil abiotic properties were determined in all soils.Important Findings The establishment of native and invasive species was signifi-cantly affected by the microhabitat,with a higher number of seedlings under the native forest(P.pinaster).The establishment of A.dealbata seedlings was also significantly promoted by its own soil.A negligible effect of allelopathy was detected on the establishment and growth of both invasive and native species.We conclude that(i)the main factor affecting seedling establish-ment was microhabitat rather than changes in soil properties or allelopathy,(ii)soil modifications by A.dealbata promote the establishment of its own seedlings,contributing to the progress of invasion and(iii)allelochemicals released by A.dealbata do not seem to play a key role for the establishment of native and invasive plants under field conditions in the European non-native range.
基金supported by and the Fundamental Research Funds for the National Science Foundation of China (No. 41171238)the Ministry of Science and Technology (No. 2013BAD11B01)+1 种基金the Central Universities (No. KYTZ201404)the Nonprofit Research Foundation for Agriculture (No. 200903003)
文摘The aim of this experiment was to determine the impacts of climate change on soil profile concentrations and diffusion effluxes of methane in a rice-wheat annual rotation ecosystem in Southeastern China. We initiated a field experiment with four treatments:ambient conditions(CKs), CO2 concentration elevated to - 500 μmol/mol(FACE),temperature elevated by ca. 2°C(T) and combined elevation of CO2 concentration and temperature(FACE + T). A multilevel sampling probe was designed to collect the soil gas at four different depths, namely, 7 cm, 15 cm, 30 cm and 50 cm. Methane concentrations were higher during the rice season and decreased with depth, while lower during the wheat season and increased with depth. Compared to CK, mean methane concentration was increased by 42%, 57% and 71% under the FACE, FACE + T and T treatments, respectively, at the 7 cm depth during the rice season(p 〈 0.05). Mean methane diffusion effluxes to the 7 cm depth were positive in the rice season and negative in the wheat season, resulting in the paddy field being a source and weak sink, respectively. Moreover, mean methane diffusion effluxes in the rice season were 0.94, 1.19 and 1.42 mg C/(m^2·hr) in the FACE,FACE + T and T treatments, respectively, being clearly higher than that in the CK. The results indicated that elevated atmospheric CO2 concentration and temperature could significantly increase soil profile methane concentrations and their effluxes from a rice-wheat field annual rotation ecosystem(p 〈 0.05).
基金supported by the Public Welfare Project of the National Scientific Research Institution (No.CAFRIFEEP201101),Chinathe National Biological Specimens and Resources Sharing Platform in Nature Reserve (No.2005DKA21404)
文摘Acidobacteria is one of the most dominant and abundant phyla in soil,and was believed to have a wide range of metabolic and genetic functions. Relatively little is known about its community structure and elevational diversity patterns. We selected four elevation gradients from 1000 to 2800 m with typical vegetation types of the northern slope of Shennongjia Mountain in central China. The vegetation types were evergreen broadleaved forest,deciduous broadleaved forest,coniferous forest and sub-alpine shrubs. We analyzed the soil acidobacterial community composition,elevational patterns and the relationship between Acidobacteria subdivisions and soil enzyme activities by using the 16 S rRNA meta-sequencing technique and multivariate statistical analysis. The result found that 19 known subdivisions as well as an unclassified phylotype were presented in these forest sites,and Subdivision 6 has the highest number of detectable operational taxonomic units(OTUs). A significant single peak distribution pattern(P 〈 0.05) between the OTU number and the elevation was observed. The Jaccard and Bray–Curtis index analysis showed that the soil Acidobacteria compositional similarity significantly decreased(P 〈 0.01) with the increase in elevation distance. Mantel test analysis showed the most of the soil Acidobacteria subdivisions had the significant relationship(P 〈 0.01) with different soil enzymes. Therefore,soil Acidobacteria may be involved in different ecosystem functions in global elemental cycles. Partial Mantel tests and CCA analysis showed that soil pH,soil temperature and plant diversity may be the key factors in shaping the soil Acidobacterial community structure.
基金We thank the China National Space Administration for providing access to the lunar sample CE5C0200YJFM00302This work was supported by the Strategic Priority Research Program of Chinese Academy of Sciences(XDB 41000000)+4 种基金the National Natural Science Foundation of China(42273042 and 41931077)the Technical Advanced Research Project of Civil Space(D020201)the Youth Innovation Promotion Association,Chinese Academy of Sciences(2020395)the Key Research Program of Frontier Sciences,Chinese Academy of Sciences(ZDBS-SSWJSC007-10 and QYZDY-SSW-DQC028)China Postdoctoral Science Foundation(2022M720216).