[Objective]The construction of weirs changes the hydraulic characteristics of rivers and affects the structure of phytoplankton communities and the health of aquatic ecosystems in the river.This study aims to explore ...[Objective]The construction of weirs changes the hydraulic characteristics of rivers and affects the structure of phytoplankton communities and the health of aquatic ecosystems in the river.This study aims to explore the nonlinear response relationship between phytoplankton community structure and its driving factors in spring and autumn in Furong Creek under the construction of cascade weirs.[Methods]The structure of phytoplankton communities and related environmental factors were investigated in Furong Creek from 2023 to 2024.This study focused on the analysis of the changes of nutrient concentrations and biomass of phytoplankton in autumn and spring within the same dry season in Furong Creek.Redundancy analysis was used to identify the key factors influencing the structure of phytoplankton communities.The MIKE 11 model was employed to simulate the hydrodynamic changes in the river.Combined with total nitrogen and permanganate index,a GAM model of phytoplankton diversity index and hydrodynamic factors was developed,and the change of phytoplankton diversity after the optimized layout of the cascade weirs was fitted.[Results]The result showed that the annual average value of Shannon-Wiener diversity index of phytoplankton in Furong Creek was 2.79,which was in a state of mild pollution.A total of 239 species from 95 genera in 8 phyla were identified.Among the phytoplankton,Chlorophyta was the dominant group throughout the year in Furong Creek,followed by Bacillariophyta and Cyanophyta.The cell abundance of phytoplankton ranged from 3.11 to 20.64 mg/L and from 0.23 to 6.31 mg/L in spring and autumn,which indicated a clear seasonal succession of phytoplankton community structure.Compared with autumn,the relative abundance of Cyanophyta significantly decreased in spring across the whole river section,while Chrysophyta and Dinophyta showed significant increase at some monitoring sites,leading to water bloom phenomenon and a noticeable decline in the diversity of phytoplankton.The dominant species in the water bodies throughout the year were Cyclotella catenata,Chlorella vulgaris,Scenedesmus bijuga,Scenedesmus quadricauda,Chroomonas acuta,Cryptomonas ovata,and Cryptomonas erosa.Redundancy analysis(RDA)showed that hydrodynamic factors(v,h)and water environmental factors(TN,COD_(Mn))were the main influencing factors of phytoplankton community structure.[Conclusion]The result show that the nutrient concentration,phytoplankton biomass,and density in Furong Creek in spring are significantly higher than in autumn.The GAM model,constructed by combining hydrodynamic and environmental factors,can effectively reflect the nonlinear relationship between phytoplankton diversity index and its driving factors.In spring,with an increase in nutrient concentration,the habitat conditions of low flow speed and high water depths formed by overflow weirs will lead to a decrease in the Shannon-Wiener index of phytoplankton and an intensified risk of eutrophication.However,a reasonable layout scheme of cascade weirs will improve the diversity of phytoplankton and reduce the risk of eutrophication in the river.The findings of this study can help deepen the understanding of the ecological and environmental effects of cascade weir construction in the river.展开更多
Continuous cropping can lead to soil environment deterioration,cause plant health problems,and reduce crop productivity.However,the response mechanisms of soil microbial co-occurrence patterns to the duration of conti...Continuous cropping can lead to soil environment deterioration,cause plant health problems,and reduce crop productivity.However,the response mechanisms of soil microbial co-occurrence patterns to the duration of continuous melon cropping remain poorly understood.Here,we employed the metagenomic techniques to comparatively investigate the bulk and rhizosphere soil microbial communities of major melon-producing regions(where the duration of continuous melon cropping ranges from 1 to 30 a)in the eastern and southern parts of Xinjiang Uygur Autonomous Region,China.The results showed that soil pH clearly decreased with increasing melon cropping duration,while soil electrical conductivity(EC)and the other soil nutrient indices increased with increasing melon cropping duration(with the exception of AN and TK in the southern melon-producing region).The most dominant bacterial phyla were Proteobacteria and Actinobacteria,and the most abundant fungal phyla were Ascomycota and Mucoromycota.Redundancy analysis(RDA)indicated that soil pH and EC had no significant effects on the bacterial communities.However,after many years of continuous melon cropping in the southern melon-producing region,fungal communities were significantly negatively correlated with soil pH and significantly positively correlated with soil EC(P<0.050).Co-occurrence network analysis showed that continuous melon cropping increased the complexity but decreased the connectivity of the cross-domain microbial networks.Moreover,the enrichment patterns of microorganisms in the main microbial network modules varied significantly with the duration of continuous melon cropping.Based on the analysis of keystone taxa,we found that continuous melon cropping increased some plant pathogens(e.g.,Fusarium and Stagonospora)but decreased beneficial bacteria(e.g.,Mesorhizobium and Pseudoxanthomonas).In conclusion,this study has greatly enhanced the understanding of the effects of continuous melon cropping on alterations in the microbial community structure and ecological networks in Xinjiang.展开更多
Grassland shrub encroachment is a phenomenon that is prevalent in arid and semi-arid regions worldwide,impacting grassland ecosystems in several ways.In the context of escalating climate change and human activities,ex...Grassland shrub encroachment is a phenomenon that is prevalent in arid and semi-arid regions worldwide,impacting grassland ecosystems in several ways.In the context of escalating climate change and human activities,examining the nutrient and stoichiometric characteristics of Spiraea shrubs in grassland ecosystems,along with their relationships with environmental factors,can yield valuable insights into the nutrient utilization and survival strategies of these shrubs.This,in turn,offers a scientific foundation for developing future conservation measures.This study was conducted in July 2023 in the Altay Mountains,Northwest China,where Spiraea shrubs thrive across five grassland types:temperate steppe desert,temperate desert steppe,temperate steppe,temperate meadow steppe,and mountain meadow.Leaf and soil samples were collected from each grassland type to analyze the concentrations of carbon(C),nitrogen(N),and phosphorus(P),as well as the stoichiometric characteristics of both the leaves and soil.Subsequently,correlation analysis and redundancy analysis(RDA)were conducted to investigate the variations in leaf C,N,and P concentrations and leaf stoichiometry of Spiraea shrubs as well as their influencing factors.The results indicated the presence of significant or highly significant differences(P<0.050)in the leaf C,N,and P concentrations and leaf stoichiometry(C:N,C:P,and N:P ratios)of Spiraea shrubs across the five grassland types.The N:P ratios of Spiraea shrub leaves in the five grassland types ranged from 7.37 to 11.77,suggesting that N availability generally limits the growth of Spiraea shrubs.Results of RDA revealed that the most significant contributors to the C,N,and P concentrations and stoichiometric characteristics of Spiraea shrub leaves were in the following order:soil total N>mean annual precipitation>elevation>soil pH>soil organic C>mean annual temperature.These factors had contribution rates of 35.32%,13.19%,10.20%,8.82%,8.34%,and 6.48%,respectively.It was determined that soil nutrients have a greater impact on the growth and nutrient accumulation of Spiraea shrubs compared to climatic factors.This study makes an important contribution to the theoretical basis and data support,enabling a deeper understanding of the response mechanisms of shrub species in the grassland ecosystems of the Altay Mountains to climate change.展开更多
In this paper, one of the most classical statistical methods, Canonical Correlation Analysis (CCA) is applied to identify quantitatively the driving forces of landuse structure in Yulin Prefecture. The main analysis i...In this paper, one of the most classical statistical methods, Canonical Correlation Analysis (CCA) is applied to identify quantitatively the driving forces of landuse structure in Yulin Prefecture. The main analysis is carried out through the software SPSS with the data on the level of towns and townships in 1992. The results indicate that landuse structure is determined by comprehensive action of different factors. Landuse structure with rural characteristics is mainly determined by geographical factors such as the elevation, temperature and precipitation, while the landuse structure with urban characteristics is mainly determined by demographic and socioeconomic conditions. At the same time, tests were carried out through the canonical correlation coefficient and redundancy analysis.展开更多
As an important means to solve water shortage,reclaimed water has been widely used for landscape water supply.However,with the emergence of large-scale epidemic diseases such as SARS,avian influenza and COVID-19 in re...As an important means to solve water shortage,reclaimed water has been widely used for landscape water supply.However,with the emergence of large-scale epidemic diseases such as SARS,avian influenza and COVID-19 in recent years,people are increasingly concerned about the public health safety of reclaimed water discharged into landscape water,especially the pathogenic microorganisms in it.In this study,the water quality and microorganisms of the Old Summer Palace,a landscape water body with reclaimed water as the only replenishment water source,were tracked through long-term dynamic monitoring.And the health risks of indicator microorganisms were analyzed using Quantitative Microbial Risk Assessment(QMRA).It was found that the concentration of indicator microorganisms Enterococcus(ENT),Escherichia coli(EC)and Fecal coliform(FC)generally showed an upward trend along the direction of water flow and increased by more than 0.6 log at the end of the flow.The concentrations of indicator microorganisms were higher in summer and autumn than those in spring.And there was a positive correlation between the concentration of indicator microorganisms and COD.Further research suggested that increased concentration of indicator microorganisms also led to increased health risks,which were more than 30%higher in other areas of the park than the water inlet area and required special attention.In addition,(water)surface operation exposure pathway had much higher health risks than other pathways and people in related occupations were advised to take precautions to reduce the risks.展开更多
Effects of suction dredging on water quality and zooplankton community structure in a shallow of eutrophic lake, were evaluated. The results showed that a decreasing trend for levels of phosphorus, organic matter, tot...Effects of suction dredging on water quality and zooplankton community structure in a shallow of eutrophic lake, were evaluated. The results showed that a decreasing trend for levels of phosphorus, organic matter, total suspended solids, Chlorophyll a and Secchi transparency in the water column was found, while levels of water depth, electrical conductivity, total dissolved solids and NO3^--N concentration increased markedly post-dredging. The effects of dredging on dissolved oxygen, pH value and temperature were almost negligible. The zooplankton community structure responded rapidly to the environmental changes caused mainly by dredging. As a result, the abundance of rotifers decreased, while the density of zooplanktonic crustaceans increased markedly. The representative taxa were Brachionus angularis, B. budapestinensis, B. diversicornis, Synchaeta spp. and Neodiaptomus schmackeri. A distinct relationship between zooplankton taxa composition and their environment, unraveled by a redundancy analysis, indicating that the measured environment contributed to the variations in the zooplankton community structure to some extent. The first four synthetic environmental variables explained 51.7% of the taxonomic structure. Therefore, with the reduction of internal nutrient load and a shift in dominance by less eutrophic species, it inferred that dredging might be one of effective measures for environmental improvements of such lakes.展开更多
To explore the spatial heterogeneity of plankton communities in a deep artificial lake （Songhua Lake, China）, samples were collected at seven sites. Samples were investigated by denaturing gradient gel electrophores...To explore the spatial heterogeneity of plankton communities in a deep artificial lake （Songhua Lake, China）, samples were collected at seven sites. Samples were investigated by denaturing gradient gel electrophoresis （DGGE） analysis of the PCR-amplified 16S and 18S rRNA genes and specific bands were sequenced. Cluster analysis of the DGGE profiles revealed that all of the samples grouped into two distinct clusters, in accordance with sampling site; while in each cluster, the divergence of sub-clusters correlated with sampling depth. Sequence analysis of selected dominant DGGE bands revealed that most sequenced phylotypes （84%） exhibited 〉97% similarity to the closest sequences in GenBank, and were affiliated with ten common freshwater plankton phyla （Proteobacteria, Actinobacteria, Bacteroidetes, Cyanobacteria, Bacillariophyta, Pyrrophyta, Cryptophyta, Ciliophora, Stramenopiles, and Rotifera）. Several of these groups are also found worldwide, indicating the cosmopolitan distribution of the phylotypes. The relationships between DGGE patterns and environmental factors were analyzed by redundancy analysis （RDA）. The results suggested that, total nitrogen, nitrate, nitrite, temperature were strongly correlated with the variation ammonia, and CODMn concentrations, and water in plankton composition.展开更多
The Yellow River Basin(YRB)occupies an important position in China’s socioeconomic development and ecological conservation efforts.Understanding the spatiotemporal characteristics of the relationships among multiple ...The Yellow River Basin(YRB)occupies an important position in China’s socioeconomic development and ecological conservation efforts.Understanding the spatiotemporal characteristics of the relationships among multiple ecosystem services(ESs)and their drivers is crucial for regional sustainable development and human-earth system coordination.This study simulated food production(FP),water yield(WY),net primary production(NPP),soil conservation(SC),and habitat quality(HQ)in the YRB from 2000 to 2020,and evaluated the spatial evolution and the relationship of ESs at the raster scale.Redundancy analysis was used to identify the impact of natural,socioeconomic,and landscape patterns on the relationship between ESs.The results demonstrated that the average HQ per unit area decreased by 18.10%,while SC,NPP,WY,and FP increased by 42.68%,47.63%,30.82%,and 67.10%,respectively,from 2000 to 2020.The relationship between ESs in the YRB was dominated by weak trade-offs and weak synergies at a temporal scale,with the trade-offs strengthened in the Upper Yellow River Basin(UYRB)and the Middle Yellow River Basin(MYRB),and synergies strengthened in the Lower Yellow River Basin(LYRB).At the spatial scale,the relationships between HQ and WY,HQ and SC,HQ and NPP,FP and SC,and FP and HQ were all dominated by trade-offs,while other ES pairs were mostly based on synergistic relationships.In the YRB,the relationships among ESs were mainly influenced by human disturbance,precipitation,and land-use and exploitation intensity.Specifically,the trade-offs among ESs in the UYRB were primarily affected by precipitation,and those in the MYRB and LYRB by human disturbance.The heterogeneity of the landscape could also effectively promote synergies among ESs.This study could provide insights into trade-offs and synergies among ESs and their driving forces and lay a foundation for ecological restoration and sustainable development of ESs in the YRB.展开更多
A plethora of information is available on the effects of salinity on plant growth and soil physico-chemical properties,but the effects on soil organisms are often neglected.Thus,a systematic investigation of how soil ...A plethora of information is available on the effects of salinity on plant growth and soil physico-chemical properties,but the effects on soil organisms are often neglected.Thus,a systematic investigation of how soil biodiversity,including bacteria,nematodes,mites,and earthworms,changes along saline gradients was conducted along the Bohai Sea coast at Laizhou City,Shandong Province,China,with 30 soil samples randomly selected and classified by salinity into two categories:saline and non-saline.Testing revealed a significantly higher abundance of the surveyed organisms in non-saline soils.The redundancy analysis showed that a negative correlation was observed between electrical conductivity and soil organism abundance in saline soil,but not in non-saline soil.Soil organic matter,available nitrogen,and total nitrogen all positively affected organism abundance in both saline and non-saline soils.The richness and Shannon diversity of nematodes were significantly higher in non-saline soils,but were not significantly different between soil types for other organisms.None of the environmental factors surveyed was obviously related to soil organism diversity.Consequently,our results suggested that soil electrical conductivity only negatively affected soil organisms in saline soil,while soil fertility positively affected soil organisms in both saline and non-saline soils.展开更多
Effects of the heavy metal copper(Cu), the metalloid arsenic(As), and the antibiotic oxytetracycline(OTC) on bacterial community structure and diversity during cow and pig manure composting were investigated. Eight tr...Effects of the heavy metal copper(Cu), the metalloid arsenic(As), and the antibiotic oxytetracycline(OTC) on bacterial community structure and diversity during cow and pig manure composting were investigated. Eight treatments were applied, four to each manure type, namely cow manure with:(1) no additives(control),(2) addition of heavy metal and metalloid,(3) addition of OTC and(4) addition of OTC with heavy metal and metalloid;and pig manure with:(5) no additives(control),(6) addition of heavy metal and metalloid,(7) addition of OTC and(8) addition of OTC with heavy metal and metalloid. After 35 days of composting, according to the alpha diversity indices, the combination treatment(OTC with heavy metal and metalloid) in pig manure was less harmful to microbial diversity than the control or heavy metal and metalloid treatments. In cow manure, the treatment with heavy metal and metalloid was the most harmful to the microbial community, followed by the combination and OTC treatments. The OTC and combination treatments had negative effects on the relative abundance of microbes in cow manure composts. The dominant phyla in both manure composts included Actinobacteria, Bacteroidetes, Firmicutes, and Proteobacteria. The microbial diversity relative abundance transformation was dependent on the composting time. Redundancy analysis(RDA) revealed that environmental parameters had the most influence on the bacterial communities. In conclusion, the composting process is the most sustainable technology for reducing heavy metal and metalloid impacts and antibiotic contamination in cow and pig manure. The physicochemical property variations in the manures had a significant effect on the microbial community during the composting process. This study provides an improved understanding of bacterial community composition and its changes during the composting process.展开更多
Reservoirs are an important water source in many densely populated areas in southwest China.Phytoplankton play an essential role in maintaining the structure and function of reservoir ecosystems.Understanding the succ...Reservoirs are an important water source in many densely populated areas in southwest China.Phytoplankton play an essential role in maintaining the structure and function of reservoir ecosystems.Understanding the succession in phytoplankton communities and the factors driving it are essential for eff ective water quality management in drinking water reservoirs.In this study,water samples were collected monthly at the surface layers from March 2016 to December 2019 in Hongfeng Reservoir,southwest China.The relationship between functional group succession was analyzed based on nonmetric multidimensional scaling analysis(NMDS),redundancy analysis(RDA),succession rate,and other analysis methods.The results showed distinct shifts in the community structure of phytoplankton functional groups within study period.The Cyclotella sp.was dominant in 2016 and 2017,and Pseudanabaena limnetica was the dominant group in 2018 and 2019.It appears that the phytoplankton composition and biomass are closely related to the water temperature and nutrient status in this reservoir.The results clearly showed that the permanganate index(COD_(Mn))was the key factor of dramatic phytoplankton functional group succession,and the change in succession rates was closely caused by total nitrogen concentration(TN).Therefore,the succession pattern and key factors of Hongfeng Reservoir revealed in this study were important guidance for the management of drinking water reservoirs in southwest China.A reasonable limit on exogenous nutrient input should be a priority,especially in high water temperature period.展开更多
A lab-scale continuously-stirred tank reactor （CSTR）, used for anaerobic co-digestion of fruit and vegetable waste （FVW） and food waste （FW） at different mixture ratios, was operated for 178 days at the organic ...A lab-scale continuously-stirred tank reactor （CSTR）, used for anaerobic co-digestion of fruit and vegetable waste （FVW） and food waste （FW） at different mixture ratios, was operated for 178 days at the organic loading rate of 3 kg VS （volatile solids）/（m3.day）. The dynamics of the Archaeal community and the correlations between environmental variables and methanogenic community structure were analyzed by polymerase chain reactions - denaturing gradient gel electrophoresis （PCR-DGGE） and redundancy analysis （RDA）, respectively. PCR-DGGE results demonstrated that the mixture ratio of FVW to FW altered the community composition of Archaea. As the FVW]FW ratio increased, Methanoculleus, Methanosaeta and Methanosarcina became the predominant methanogens in the community. Redundancy analysis results indicated that the shift of the methanogenic community was significantly correlated with the composition of acidogenic products and methane production yield. Different mixture ratios of substrates led to different compositions of intermediate metabolites, which may affect the methanogenic community. These results suggested that the analysis of microbial communities could be used to diagnose anaerobic processes.展开更多
We evaluated the seasonal variation in plankton community composition in an artificial lake. We conducted microscopic analysis and denaturing gradient gel electrophoresis (DGGE) of PCR-amplified partial 16S rRNAand 18...We evaluated the seasonal variation in plankton community composition in an artificial lake. We conducted microscopic analysis and denaturing gradient gel electrophoresis (DGGE) of PCR-amplified partial 16S rRNAand 18S rRNAgenes to characterize the plankton community. The clustering of unweighted pair group method with arithmetic mean (UPGMA) was then used to investigate the similarity of these plankton communities. DGGE fingerprinting revealed that samples collected at the different sites within a season shared high similarity and were generally grouped together. In contrast, we did not observe any seasonal variation based on microscopic analysis. Redundancy analysis (RDA) of the plankton operational taxonomic units (OTUs) in relation to environmental factors revealed that transparency was negatively correlated with the first axis (R=-0.931), and temperature and total phosphorus (TP) were positively correlated with the first axis (R=0.736 and R=0.660, respectively). In conclusion, plankton communities in the artificial lake exhibited significant seasonal variation. Transparency, phosphorus and temperature appear to be the major factors driving the differences in plankton composition.展开更多
The reconstruction of paleovegetation and paleoclimate requires an understanding of the relationships between surface pollen assemblages and modern vegetation and climate.Here,we analyzed the characteristics of surfac...The reconstruction of paleovegetation and paleoclimate requires an understanding of the relationships between surface pollen assemblages and modern vegetation and climate.Here,we analyzed the characteristics of surface pollen assemblages across different vegetation zones in the Tianshan Mountains.Using surface pollen analysis and vegetation sample surveys at 75 sites on the northern slopes of the Tianshan Mountains,we determined the correlation between the percentage of dominant pollen types and the corresponding vegetation cover.Redundancy analysis was used to investigate the relationships between surface pollen assemblages and environmental factors.Our results show that the Tianshan Mountains contain several distinct ecological regions,which can be divided into five main vegetation zones from low to high altitudes:mountain desert zone(Hutubi County(HTB):500-1300 m;Qitai County(QT):1000-1600 m),mountain steppe zone(HTB:1400-1600 m;QT:1650-1800 m),mountain forest zone(HTB:1650-2525 m;QT:1850-2450 m),subalpine meadow zone(HTB:2550-2600 m;QT:2500-2600 m),and alpine mat vegetation zone(HTB:2625-2700 m;QT:2625-2750 m).The surface pollen assemblages of different vegetation zones can accurately reflect the characteristics of the mountainous vegetation patterns on the northern slopes of the Tianshan Mountains when excluding the widespread occurrence of Chenopodiaceae,Artemisia,and Picea pollen.Both average annual precipitation(P_(ann))and annual average temperature(T_(ann))affect the distribution of surface pollen assemblages.Moreover,P_(ann) is the primary environmental factor affecting surface pollen assemblages in this region.A significant correlation exists between the pollen percentage and vegetation cover of Picea,Chenopodiaceae,Artemisia,and Asteraceae.Moreover,Picea,Chenopodiaceae,and Artemisia pollen are over-represented compared with their corresponding vegetation cover.The Asteraceae pollen percentage roughly reflects the distribution of a species within the local vegetation.These results have important implications for enhancing our understanding of the relationship between surface pollen assemblages and modern vegetation and climate.展开更多
Accurate evaluation of soil productivity has been a long-standing challenge. Although numerous models for productivity assessment exist, most are cumbersome to use and require substantial parameter inputs. We develope...Accurate evaluation of soil productivity has been a long-standing challenge. Although numerous models for productivity assessment exist, most are cumbersome to use and require substantial parameter inputs. We developed a new empirical soil productivity model based on field investigations of soil erosion, soil physieoehemieal properties, and crop yields in the dry-hot valleys （DHVs） in China. We found that soil pH, and organic matter and available potassium contents significantly affected crop yields under eroded conditions of the DHVs. Moreover, available potassium content was the key factor affecting soil productivity. We then modified an existing soil productivity model by adding the following parameters： contents of effective water, potassium, organic matter, and clay, soil pH, and root weighting factor. The modified soil productivity model explained 63.5% of the crop yield. We concluded that the new model was simple, realistic, and exhibited strong predictability. In addition to providing an accurate assessment of soil productivity,our model could potentially be applied as a soil module in comprehensive crop models.展开更多
Acid mine drainage(AMD)has become a widespread environmental issue and its toxicity can cause permanent damage to the ecosystem.However,there are few studies focusing on the formation of AMD under moderately thermophi...Acid mine drainage(AMD)has become a widespread environmental issue and its toxicity can cause permanent damage to the ecosystem.However,there are few studies focusing on the formation of AMD under moderately thermophilic conditions,hence we employed X-ray diffraction(XRD),scanning electron microscopy(SEM),X-ray photoelectron spectroscopy(XPS)and 16S rRNA sequencing to study the dissolution of pyrite and bornite by a moderate thermophilic consortium,and explored the role of free and attached microorganisms in the formation of AMD.The consortium mainly comprised Acidithiobacillus caldus,Leptospirillum ferriphilum and Sulfobacillus thermosulfidooxidans.The results indicated that total iron in pyrite solution system reached 33.45 g/L on the 12th day,and the copper dissolution rate of bornite dissolution reached 91.8%on the 24th day.SEM results indicated that the surfaces of pyrite and bornite were significantly corroded by microorganisms.XRD and XPS results showed that ore residues contained jarosite,and the dissolving residue of bornite contained elemental sulfur.The dominant bacterial genus in pyrite dissolution was A.caldus,and L.ferriphilum in bornite dissolution.To sum up,microbes significantly accelerated the mineral dissolution process and promoted the formation of AMD.展开更多
Multivariate statistical analyses were used to assess the contents and distributions of trace elements in agricultural soils in Xinzhou of Shanxi Province, China, and to identify their sources. Samples with high level...Multivariate statistical analyses were used to assess the contents and distributions of trace elements in agricultural soils in Xinzhou of Shanxi Province, China, and to identify their sources. Samples with high levels of trace elements were concentrated in eastern Xinzhou, with contents declining from the east to west. Principal component and redundancy analyses revealed strong correlations among Co, Cu, Mn, Ni, Se, V, and Zn contents, suggesting that these elements were derived from similar parent materials. There were also strong correlations between the contents of these elements and soil properties. Contents of Cd and Pb were significantly higher in the agricultural soil samples than in the background soil samples(P < 0.05), and were higher in areas with higher levels of gross domestic product but decreased with distance to the nearest road. Therefore, human activities appear to have a strong influence on the Cd and Pb distribution patterns. A novel artificial neural network(ANN) model, using environmental input data, was used to predict the soil Cd and Pb contents of specified test dates. The performances of the ANN model and a traditional multilinear model were compared. The ANN model could successfully predict Cd and Pb content distributions, projecting that soil Cd and Pb contents will increase by 128% and 25%, respectively, by 2020. The results thus indicated that the economic condition of an area has a greater effect on trace element contents and distributions in the soil than the scale of the economy itself.展开更多
This study aimed to determine the characteristics of soil microbial community composition and its relationship with soil chemical properties during natural recovery in the Loess Plateau.The soil microbial community co...This study aimed to determine the characteristics of soil microbial community composition and its relationship with soil chemical properties during natural recovery in the Loess Plateau.The soil microbial community composition was analyzed by comparing the soil microbial phospholipid fatty acids（PLFAs） of eight croplands abandoned for 1,3,5,10,13,15,20,and 30 yr in the Dunshan watershed,northern Loess Plateau,China.The results showed that soil organic carbon,total nitrogen,soil microbial biomass carbon,and soil microbial biomass nitrogen significantly increased with the abandonment duration,whereas the metabolic quotient significantly decreased.The Shannon richness and Shannon evenness of PLFAs significantly increased after 10 yr of abandonment.Gram-negative,Gram-positive,bacterial,fungal,and total PLFAs linearly increased with increased abandonment duration.Redundancy analysis showed that the abandonment duration was the most important environmental factor in determining the PLFA microbial community composition.The soil microbial PLFAs changed from anteiso-to iso-,unsaturated to saturated,and short-to long-chain during natural recovery.Therefore,in the Loess Plateau,cropland abandonment for natural recovery resulted in the increase of the soil microbial PLFA biomass and microbial PLFA species and changed the microbial from chemolithotrophic to a more heterotrophic community.展开更多
Arsenic （As） pollutants generated by human activities in karst areas flow into subterranean streams and contaminate groundwater easily because of the unique hydrogeological characteristics of karst areas. To elucida...Arsenic （As） pollutants generated by human activities in karst areas flow into subterranean streams and contaminate groundwater easily because of the unique hydrogeological characteristics of karst areas. To elucidate the reaction mechanisms of arsenic in karst subterranean streams, physical-chemical analysis was conducted by an inductively coupled plasma mass spectrometer and an X-ray fluorescence spectrometer. The results show that inorganic species account for most of the total arsenic, whereas organic arsenic is not detected or occurs in infinitesimal amounts. As（III） accounts for 51.0% ± 9.9% of the total inorganic arsenic. Arsenic attenuation occurs and the attenuation rates of total As, As（III） and As（V） in the Lihu subterranean stream are 51%, 36% and 59%, respectively. To fully explain the main geochemical factors influencing arsenic attenuation, SPSS 13.0 and CANOCO 4.5 bundled with CanoDraw for Windows were used for simple statistical analysis and redundancy analysis （RDA）. Eight main factors, i.e., sediment iron （SFe）, sediment aluminum （SAI）, sediment calcium （SCa）, sediment organic matter （SOM）, sediment manganese （SMn）, water calcium （WCa^2＋）, water magnesium （WMg^2＋）, and water bicarbonate ion （WILCOX） were extracted from thirteen indicators. Their impacts on arsenic content rank as： SFe〉SCa〉WCa^2＋〉SAl〉wHCO3^-〉SMn〉SOM〉WMg^2＋. Of these factors, SFe, SAl, SCa, SOM, SMn, WMg^2＋ and WCa＆2＋ promote arsenic attenuation, whereas WHCO3^- inhibits it. Further investigation revealed that the redox potential （Eh） and pH are adverse to arsenic removal. The dramatic distinction between karst and non-karst terrain is that calcium and bicarbonate are the primary factors influencing arsenic migration in karst areas due to the high calcium concentration and alkalinity of karst water.展开更多
文摘[Objective]The construction of weirs changes the hydraulic characteristics of rivers and affects the structure of phytoplankton communities and the health of aquatic ecosystems in the river.This study aims to explore the nonlinear response relationship between phytoplankton community structure and its driving factors in spring and autumn in Furong Creek under the construction of cascade weirs.[Methods]The structure of phytoplankton communities and related environmental factors were investigated in Furong Creek from 2023 to 2024.This study focused on the analysis of the changes of nutrient concentrations and biomass of phytoplankton in autumn and spring within the same dry season in Furong Creek.Redundancy analysis was used to identify the key factors influencing the structure of phytoplankton communities.The MIKE 11 model was employed to simulate the hydrodynamic changes in the river.Combined with total nitrogen and permanganate index,a GAM model of phytoplankton diversity index and hydrodynamic factors was developed,and the change of phytoplankton diversity after the optimized layout of the cascade weirs was fitted.[Results]The result showed that the annual average value of Shannon-Wiener diversity index of phytoplankton in Furong Creek was 2.79,which was in a state of mild pollution.A total of 239 species from 95 genera in 8 phyla were identified.Among the phytoplankton,Chlorophyta was the dominant group throughout the year in Furong Creek,followed by Bacillariophyta and Cyanophyta.The cell abundance of phytoplankton ranged from 3.11 to 20.64 mg/L and from 0.23 to 6.31 mg/L in spring and autumn,which indicated a clear seasonal succession of phytoplankton community structure.Compared with autumn,the relative abundance of Cyanophyta significantly decreased in spring across the whole river section,while Chrysophyta and Dinophyta showed significant increase at some monitoring sites,leading to water bloom phenomenon and a noticeable decline in the diversity of phytoplankton.The dominant species in the water bodies throughout the year were Cyclotella catenata,Chlorella vulgaris,Scenedesmus bijuga,Scenedesmus quadricauda,Chroomonas acuta,Cryptomonas ovata,and Cryptomonas erosa.Redundancy analysis(RDA)showed that hydrodynamic factors(v,h)and water environmental factors(TN,COD_(Mn))were the main influencing factors of phytoplankton community structure.[Conclusion]The result show that the nutrient concentration,phytoplankton biomass,and density in Furong Creek in spring are significantly higher than in autumn.The GAM model,constructed by combining hydrodynamic and environmental factors,can effectively reflect the nonlinear relationship between phytoplankton diversity index and its driving factors.In spring,with an increase in nutrient concentration,the habitat conditions of low flow speed and high water depths formed by overflow weirs will lead to a decrease in the Shannon-Wiener index of phytoplankton and an intensified risk of eutrophication.However,a reasonable layout scheme of cascade weirs will improve the diversity of phytoplankton and reduce the risk of eutrophication in the river.The findings of this study can help deepen the understanding of the ecological and environmental effects of cascade weir construction in the river.
基金funded by the Major Science and Technology Projects of Xinjiang Uygur Autonomous Region(2022A02007-4)the Xinjiang Uygur Autonomous Region Natural Science Foundation Youth Project(2024D01B31)the Graduate Student Research Innovation Project of Xinjiang Agricultural University(XJAUGRI2024033).
文摘Continuous cropping can lead to soil environment deterioration,cause plant health problems,and reduce crop productivity.However,the response mechanisms of soil microbial co-occurrence patterns to the duration of continuous melon cropping remain poorly understood.Here,we employed the metagenomic techniques to comparatively investigate the bulk and rhizosphere soil microbial communities of major melon-producing regions(where the duration of continuous melon cropping ranges from 1 to 30 a)in the eastern and southern parts of Xinjiang Uygur Autonomous Region,China.The results showed that soil pH clearly decreased with increasing melon cropping duration,while soil electrical conductivity(EC)and the other soil nutrient indices increased with increasing melon cropping duration(with the exception of AN and TK in the southern melon-producing region).The most dominant bacterial phyla were Proteobacteria and Actinobacteria,and the most abundant fungal phyla were Ascomycota and Mucoromycota.Redundancy analysis(RDA)indicated that soil pH and EC had no significant effects on the bacterial communities.However,after many years of continuous melon cropping in the southern melon-producing region,fungal communities were significantly negatively correlated with soil pH and significantly positively correlated with soil EC(P<0.050).Co-occurrence network analysis showed that continuous melon cropping increased the complexity but decreased the connectivity of the cross-domain microbial networks.Moreover,the enrichment patterns of microorganisms in the main microbial network modules varied significantly with the duration of continuous melon cropping.Based on the analysis of keystone taxa,we found that continuous melon cropping increased some plant pathogens(e.g.,Fusarium and Stagonospora)but decreased beneficial bacteria(e.g.,Mesorhizobium and Pseudoxanthomonas).In conclusion,this study has greatly enhanced the understanding of the effects of continuous melon cropping on alterations in the microbial community structure and ecological networks in Xinjiang.
基金supported by the National Natural Science Foundation of China(W2412123)the Youth Top Talents Project of"Tianshan Talent"Training Plan of Xinjiang Uygur Autonomous Region,China(2022TSYCCX0011)+1 种基金the Tianshan Talents Project of Xinjiang Uygur Autonomous Region,China(2022TSYCLJ0056)the Self-deployment Program of Xinjiang Institute of Ecology and Geography,Chinese Academy of Sciences(E350030401).
文摘Grassland shrub encroachment is a phenomenon that is prevalent in arid and semi-arid regions worldwide,impacting grassland ecosystems in several ways.In the context of escalating climate change and human activities,examining the nutrient and stoichiometric characteristics of Spiraea shrubs in grassland ecosystems,along with their relationships with environmental factors,can yield valuable insights into the nutrient utilization and survival strategies of these shrubs.This,in turn,offers a scientific foundation for developing future conservation measures.This study was conducted in July 2023 in the Altay Mountains,Northwest China,where Spiraea shrubs thrive across five grassland types:temperate steppe desert,temperate desert steppe,temperate steppe,temperate meadow steppe,and mountain meadow.Leaf and soil samples were collected from each grassland type to analyze the concentrations of carbon(C),nitrogen(N),and phosphorus(P),as well as the stoichiometric characteristics of both the leaves and soil.Subsequently,correlation analysis and redundancy analysis(RDA)were conducted to investigate the variations in leaf C,N,and P concentrations and leaf stoichiometry of Spiraea shrubs as well as their influencing factors.The results indicated the presence of significant or highly significant differences(P<0.050)in the leaf C,N,and P concentrations and leaf stoichiometry(C:N,C:P,and N:P ratios)of Spiraea shrubs across the five grassland types.The N:P ratios of Spiraea shrub leaves in the five grassland types ranged from 7.37 to 11.77,suggesting that N availability generally limits the growth of Spiraea shrubs.Results of RDA revealed that the most significant contributors to the C,N,and P concentrations and stoichiometric characteristics of Spiraea shrub leaves were in the following order:soil total N>mean annual precipitation>elevation>soil pH>soil organic C>mean annual temperature.These factors had contribution rates of 35.32%,13.19%,10.20%,8.82%,8.34%,and 6.48%,respectively.It was determined that soil nutrients have a greater impact on the growth and nutrient accumulation of Spiraea shrubs compared to climatic factors.This study makes an important contribution to the theoretical basis and data support,enabling a deeper understanding of the response mechanisms of shrub species in the grassland ecosystems of the Altay Mountains to climate change.
文摘In this paper, one of the most classical statistical methods, Canonical Correlation Analysis (CCA) is applied to identify quantitatively the driving forces of landuse structure in Yulin Prefecture. The main analysis is carried out through the software SPSS with the data on the level of towns and townships in 1992. The results indicate that landuse structure is determined by comprehensive action of different factors. Landuse structure with rural characteristics is mainly determined by geographical factors such as the elevation, temperature and precipitation, while the landuse structure with urban characteristics is mainly determined by demographic and socioeconomic conditions. At the same time, tests were carried out through the canonical correlation coefficient and redundancy analysis.
基金supported by the National Natural Science Foundation of China(Nos.52070192 and 51778618).
文摘As an important means to solve water shortage,reclaimed water has been widely used for landscape water supply.However,with the emergence of large-scale epidemic diseases such as SARS,avian influenza and COVID-19 in recent years,people are increasingly concerned about the public health safety of reclaimed water discharged into landscape water,especially the pathogenic microorganisms in it.In this study,the water quality and microorganisms of the Old Summer Palace,a landscape water body with reclaimed water as the only replenishment water source,were tracked through long-term dynamic monitoring.And the health risks of indicator microorganisms were analyzed using Quantitative Microbial Risk Assessment(QMRA).It was found that the concentration of indicator microorganisms Enterococcus(ENT),Escherichia coli(EC)and Fecal coliform(FC)generally showed an upward trend along the direction of water flow and increased by more than 0.6 log at the end of the flow.The concentrations of indicator microorganisms were higher in summer and autumn than those in spring.And there was a positive correlation between the concentration of indicator microorganisms and COD.Further research suggested that increased concentration of indicator microorganisms also led to increased health risks,which were more than 30%higher in other areas of the park than the water inlet area and required special attention.In addition,(water)surface operation exposure pathway had much higher health risks than other pathways and people in related occupations were advised to take precautions to reduce the risks.
基金supported by the High-Tech Research Program (863) of China (No.2009ZX07106-002-004)the National Natural Science Foundation of China (No.30870221,20877093,50808172, 50909091)
文摘Effects of suction dredging on water quality and zooplankton community structure in a shallow of eutrophic lake, were evaluated. The results showed that a decreasing trend for levels of phosphorus, organic matter, total suspended solids, Chlorophyll a and Secchi transparency in the water column was found, while levels of water depth, electrical conductivity, total dissolved solids and NO3^--N concentration increased markedly post-dredging. The effects of dredging on dissolved oxygen, pH value and temperature were almost negligible. The zooplankton community structure responded rapidly to the environmental changes caused mainly by dredging. As a result, the abundance of rotifers decreased, while the density of zooplanktonic crustaceans increased markedly. The representative taxa were Brachionus angularis, B. budapestinensis, B. diversicornis, Synchaeta spp. and Neodiaptomus schmackeri. A distinct relationship between zooplankton taxa composition and their environment, unraveled by a redundancy analysis, indicating that the measured environment contributed to the variations in the zooplankton community structure to some extent. The first four synthetic environmental variables explained 51.7% of the taxonomic structure. Therefore, with the reduction of internal nutrient load and a shift in dominance by less eutrophic species, it inferred that dredging might be one of effective measures for environmental improvements of such lakes.
基金Supported by the National Natural Science Foundation of China(No.51178090)the National Key Technology R&D Program of China(No.2012BAJ21B02-02)the National Water Pollution Control and Management Technology Major Projects(No.2009ZX07106-001)
文摘To explore the spatial heterogeneity of plankton communities in a deep artificial lake （Songhua Lake, China）, samples were collected at seven sites. Samples were investigated by denaturing gradient gel electrophoresis （DGGE） analysis of the PCR-amplified 16S and 18S rRNA genes and specific bands were sequenced. Cluster analysis of the DGGE profiles revealed that all of the samples grouped into two distinct clusters, in accordance with sampling site; while in each cluster, the divergence of sub-clusters correlated with sampling depth. Sequence analysis of selected dominant DGGE bands revealed that most sequenced phylotypes （84%） exhibited 〉97% similarity to the closest sequences in GenBank, and were affiliated with ten common freshwater plankton phyla （Proteobacteria, Actinobacteria, Bacteroidetes, Cyanobacteria, Bacillariophyta, Pyrrophyta, Cryptophyta, Ciliophora, Stramenopiles, and Rotifera）. Several of these groups are also found worldwide, indicating the cosmopolitan distribution of the phylotypes. The relationships between DGGE patterns and environmental factors were analyzed by redundancy analysis （RDA）. The results suggested that, total nitrogen, nitrate, nitrite, temperature were strongly correlated with the variation ammonia, and CODMn concentrations, and water in plankton composition.
基金National Natural Science Foundation of China,No.41931293National Natural Science Foundation of China,No.42171208The Strategic Priority Research Program of the Chinese Academy of Sciences,No.XDA23070302。
文摘The Yellow River Basin(YRB)occupies an important position in China’s socioeconomic development and ecological conservation efforts.Understanding the spatiotemporal characteristics of the relationships among multiple ecosystem services(ESs)and their drivers is crucial for regional sustainable development and human-earth system coordination.This study simulated food production(FP),water yield(WY),net primary production(NPP),soil conservation(SC),and habitat quality(HQ)in the YRB from 2000 to 2020,and evaluated the spatial evolution and the relationship of ESs at the raster scale.Redundancy analysis was used to identify the impact of natural,socioeconomic,and landscape patterns on the relationship between ESs.The results demonstrated that the average HQ per unit area decreased by 18.10%,while SC,NPP,WY,and FP increased by 42.68%,47.63%,30.82%,and 67.10%,respectively,from 2000 to 2020.The relationship between ESs in the YRB was dominated by weak trade-offs and weak synergies at a temporal scale,with the trade-offs strengthened in the Upper Yellow River Basin(UYRB)and the Middle Yellow River Basin(MYRB),and synergies strengthened in the Lower Yellow River Basin(LYRB).At the spatial scale,the relationships between HQ and WY,HQ and SC,HQ and NPP,FP and SC,and FP and HQ were all dominated by trade-offs,while other ES pairs were mostly based on synergistic relationships.In the YRB,the relationships among ESs were mainly influenced by human disturbance,precipitation,and land-use and exploitation intensity.Specifically,the trade-offs among ESs in the UYRB were primarily affected by precipitation,and those in the MYRB and LYRB by human disturbance.The heterogeneity of the landscape could also effectively promote synergies among ESs.This study could provide insights into trade-offs and synergies among ESs and their driving forces and lay a foundation for ecological restoration and sustainable development of ESs in the YRB.
基金supported by the National Science & Technology Pillar Program during the Twelfth Five-Year Plan Period of China(No.2012BAD14B01)the Ph.D.Programs Foundation of Ministry of Education of China(No.20110008130003)
文摘A plethora of information is available on the effects of salinity on plant growth and soil physico-chemical properties,but the effects on soil organisms are often neglected.Thus,a systematic investigation of how soil biodiversity,including bacteria,nematodes,mites,and earthworms,changes along saline gradients was conducted along the Bohai Sea coast at Laizhou City,Shandong Province,China,with 30 soil samples randomly selected and classified by salinity into two categories:saline and non-saline.Testing revealed a significantly higher abundance of the surveyed organisms in non-saline soils.The redundancy analysis showed that a negative correlation was observed between electrical conductivity and soil organism abundance in saline soil,but not in non-saline soil.Soil organic matter,available nitrogen,and total nitrogen all positively affected organism abundance in both saline and non-saline soils.The richness and Shannon diversity of nematodes were significantly higher in non-saline soils,but were not significantly different between soil types for other organisms.None of the environmental factors surveyed was obviously related to soil organism diversity.Consequently,our results suggested that soil electrical conductivity only negatively affected soil organisms in saline soil,while soil fertility positively affected soil organisms in both saline and non-saline soils.
基金the National Key Technology R&D Program of China(2018YFD0500206)the National Natural Science Foundation of China(31572209,31772395 and 31972943)the Foundation for Safety of Agricultural Products by Ministry of Agriculture and Rural Affairs,China(GJFP2019033)。
文摘Effects of the heavy metal copper(Cu), the metalloid arsenic(As), and the antibiotic oxytetracycline(OTC) on bacterial community structure and diversity during cow and pig manure composting were investigated. Eight treatments were applied, four to each manure type, namely cow manure with:(1) no additives(control),(2) addition of heavy metal and metalloid,(3) addition of OTC and(4) addition of OTC with heavy metal and metalloid;and pig manure with:(5) no additives(control),(6) addition of heavy metal and metalloid,(7) addition of OTC and(8) addition of OTC with heavy metal and metalloid. After 35 days of composting, according to the alpha diversity indices, the combination treatment(OTC with heavy metal and metalloid) in pig manure was less harmful to microbial diversity than the control or heavy metal and metalloid treatments. In cow manure, the treatment with heavy metal and metalloid was the most harmful to the microbial community, followed by the combination and OTC treatments. The OTC and combination treatments had negative effects on the relative abundance of microbes in cow manure composts. The dominant phyla in both manure composts included Actinobacteria, Bacteroidetes, Firmicutes, and Proteobacteria. The microbial diversity relative abundance transformation was dependent on the composting time. Redundancy analysis(RDA) revealed that environmental parameters had the most influence on the bacterial communities. In conclusion, the composting process is the most sustainable technology for reducing heavy metal and metalloid impacts and antibiotic contamination in cow and pig manure. The physicochemical property variations in the manures had a significant effect on the microbial community during the composting process. This study provides an improved understanding of bacterial community composition and its changes during the composting process.
基金Supported by the National Natural Science Foundation of China(No.U1612442)the Science and Technology Foundation of Guizhou Province(Nos.[2020]6009,[2020]4Y009)Anton Brancelj was supported by Slovenian Research Agency(ARRS)(No.P1-0255)。
文摘Reservoirs are an important water source in many densely populated areas in southwest China.Phytoplankton play an essential role in maintaining the structure and function of reservoir ecosystems.Understanding the succession in phytoplankton communities and the factors driving it are essential for eff ective water quality management in drinking water reservoirs.In this study,water samples were collected monthly at the surface layers from March 2016 to December 2019 in Hongfeng Reservoir,southwest China.The relationship between functional group succession was analyzed based on nonmetric multidimensional scaling analysis(NMDS),redundancy analysis(RDA),succession rate,and other analysis methods.The results showed distinct shifts in the community structure of phytoplankton functional groups within study period.The Cyclotella sp.was dominant in 2016 and 2017,and Pseudanabaena limnetica was the dominant group in 2018 and 2019.It appears that the phytoplankton composition and biomass are closely related to the water temperature and nutrient status in this reservoir.The results clearly showed that the permanganate index(COD_(Mn))was the key factor of dramatic phytoplankton functional group succession,and the change in succession rates was closely caused by total nitrogen concentration(TN).Therefore,the succession pattern and key factors of Hongfeng Reservoir revealed in this study were important guidance for the management of drinking water reservoirs in southwest China.A reasonable limit on exogenous nutrient input should be a priority,especially in high water temperature period.
基金supported by the Ministry of Science and Technology of China(No.2008BADC4B16,2008BADC4B18,2008AA062401)
文摘A lab-scale continuously-stirred tank reactor （CSTR）, used for anaerobic co-digestion of fruit and vegetable waste （FVW） and food waste （FW） at different mixture ratios, was operated for 178 days at the organic loading rate of 3 kg VS （volatile solids）/（m3.day）. The dynamics of the Archaeal community and the correlations between environmental variables and methanogenic community structure were analyzed by polymerase chain reactions - denaturing gradient gel electrophoresis （PCR-DGGE） and redundancy analysis （RDA）, respectively. PCR-DGGE results demonstrated that the mixture ratio of FVW to FW altered the community composition of Archaea. As the FVW]FW ratio increased, Methanoculleus, Methanosaeta and Methanosarcina became the predominant methanogens in the community. Redundancy analysis results indicated that the shift of the methanogenic community was significantly correlated with the composition of acidogenic products and methane production yield. Different mixture ratios of substrates led to different compositions of intermediate metabolites, which may affect the methanogenic community. These results suggested that the analysis of microbial communities could be used to diagnose anaerobic processes.
基金Supported by the National Basic Research Program of China (973 Program) (No. 2007CB109205)the National Natural Science Foundation of China (No. 30970553)
文摘We evaluated the seasonal variation in plankton community composition in an artificial lake. We conducted microscopic analysis and denaturing gradient gel electrophoresis (DGGE) of PCR-amplified partial 16S rRNAand 18S rRNAgenes to characterize the plankton community. The clustering of unweighted pair group method with arithmetic mean (UPGMA) was then used to investigate the similarity of these plankton communities. DGGE fingerprinting revealed that samples collected at the different sites within a season shared high similarity and were generally grouped together. In contrast, we did not observe any seasonal variation based on microscopic analysis. Redundancy analysis (RDA) of the plankton operational taxonomic units (OTUs) in relation to environmental factors revealed that transparency was negatively correlated with the first axis (R=-0.931), and temperature and total phosphorus (TP) were positively correlated with the first axis (R=0.736 and R=0.660, respectively). In conclusion, plankton communities in the artificial lake exhibited significant seasonal variation. Transparency, phosphorus and temperature appear to be the major factors driving the differences in plankton composition.
基金supported by the National Natural Science Foundation of China(42071102).
文摘The reconstruction of paleovegetation and paleoclimate requires an understanding of the relationships between surface pollen assemblages and modern vegetation and climate.Here,we analyzed the characteristics of surface pollen assemblages across different vegetation zones in the Tianshan Mountains.Using surface pollen analysis and vegetation sample surveys at 75 sites on the northern slopes of the Tianshan Mountains,we determined the correlation between the percentage of dominant pollen types and the corresponding vegetation cover.Redundancy analysis was used to investigate the relationships between surface pollen assemblages and environmental factors.Our results show that the Tianshan Mountains contain several distinct ecological regions,which can be divided into five main vegetation zones from low to high altitudes:mountain desert zone(Hutubi County(HTB):500-1300 m;Qitai County(QT):1000-1600 m),mountain steppe zone(HTB:1400-1600 m;QT:1650-1800 m),mountain forest zone(HTB:1650-2525 m;QT:1850-2450 m),subalpine meadow zone(HTB:2550-2600 m;QT:2500-2600 m),and alpine mat vegetation zone(HTB:2625-2700 m;QT:2625-2750 m).The surface pollen assemblages of different vegetation zones can accurately reflect the characteristics of the mountainous vegetation patterns on the northern slopes of the Tianshan Mountains when excluding the widespread occurrence of Chenopodiaceae,Artemisia,and Picea pollen.Both average annual precipitation(P_(ann))and annual average temperature(T_(ann))affect the distribution of surface pollen assemblages.Moreover,P_(ann) is the primary environmental factor affecting surface pollen assemblages in this region.A significant correlation exists between the pollen percentage and vegetation cover of Picea,Chenopodiaceae,Artemisia,and Asteraceae.Moreover,Picea,Chenopodiaceae,and Artemisia pollen are over-represented compared with their corresponding vegetation cover.The Asteraceae pollen percentage roughly reflects the distribution of a species within the local vegetation.These results have important implications for enhancing our understanding of the relationship between surface pollen assemblages and modern vegetation and climate.
基金supported by the National Natural Science Foundation Project of China(Grant Nos.41561063,41401614 and 41401560)Non-profit Industry Research Project of Chinese Ministry of Water Resources(Grant No.201501045)Department of Water Resources of Yunnan Province:Water Science and Technology Project
文摘Accurate evaluation of soil productivity has been a long-standing challenge. Although numerous models for productivity assessment exist, most are cumbersome to use and require substantial parameter inputs. We developed a new empirical soil productivity model based on field investigations of soil erosion, soil physieoehemieal properties, and crop yields in the dry-hot valleys （DHVs） in China. We found that soil pH, and organic matter and available potassium contents significantly affected crop yields under eroded conditions of the DHVs. Moreover, available potassium content was the key factor affecting soil productivity. We then modified an existing soil productivity model by adding the following parameters： contents of effective water, potassium, organic matter, and clay, soil pH, and root weighting factor. The modified soil productivity model explained 63.5% of the crop yield. We concluded that the new model was simple, realistic, and exhibited strong predictability. In addition to providing an accurate assessment of soil productivity,our model could potentially be applied as a soil module in comprehensive crop models.
基金Projects(51934009,52074353)supported by the National Natural Science Foundation of ChinaProject(2019YFC1803600)supported by the National Key Research and Development Program of ChinaProject(2021JJ30855)supported by the Natural Science Foundation of Hunan Province,China。
文摘Acid mine drainage(AMD)has become a widespread environmental issue and its toxicity can cause permanent damage to the ecosystem.However,there are few studies focusing on the formation of AMD under moderately thermophilic conditions,hence we employed X-ray diffraction(XRD),scanning electron microscopy(SEM),X-ray photoelectron spectroscopy(XPS)and 16S rRNA sequencing to study the dissolution of pyrite and bornite by a moderate thermophilic consortium,and explored the role of free and attached microorganisms in the formation of AMD.The consortium mainly comprised Acidithiobacillus caldus,Leptospirillum ferriphilum and Sulfobacillus thermosulfidooxidans.The results indicated that total iron in pyrite solution system reached 33.45 g/L on the 12th day,and the copper dissolution rate of bornite dissolution reached 91.8%on the 24th day.SEM results indicated that the surfaces of pyrite and bornite were significantly corroded by microorganisms.XRD and XPS results showed that ore residues contained jarosite,and the dissolving residue of bornite contained elemental sulfur.The dominant bacterial genus in pyrite dissolution was A.caldus,and L.ferriphilum in bornite dissolution.To sum up,microbes significantly accelerated the mineral dissolution process and promoted the formation of AMD.
基金supported by the National High Technology Research and Development Program of China (863 Program) (Nos. 2012AA100601 and 2012AA101401)the National Natural Science Foundation of China (Nos. 41271338 and 41301342)
文摘Multivariate statistical analyses were used to assess the contents and distributions of trace elements in agricultural soils in Xinzhou of Shanxi Province, China, and to identify their sources. Samples with high levels of trace elements were concentrated in eastern Xinzhou, with contents declining from the east to west. Principal component and redundancy analyses revealed strong correlations among Co, Cu, Mn, Ni, Se, V, and Zn contents, suggesting that these elements were derived from similar parent materials. There were also strong correlations between the contents of these elements and soil properties. Contents of Cd and Pb were significantly higher in the agricultural soil samples than in the background soil samples(P < 0.05), and were higher in areas with higher levels of gross domestic product but decreased with distance to the nearest road. Therefore, human activities appear to have a strong influence on the Cd and Pb distribution patterns. A novel artificial neural network(ANN) model, using environmental input data, was used to predict the soil Cd and Pb contents of specified test dates. The performances of the ANN model and a traditional multilinear model were compared. The ANN model could successfully predict Cd and Pb content distributions, projecting that soil Cd and Pb contents will increase by 128% and 25%, respectively, by 2020. The results thus indicated that the economic condition of an area has a greater effect on trace element contents and distributions in the soil than the scale of the economy itself.
基金funded by the Strategic Technology Project of Chinese Academy of Sciences (XDA05060300)the Science and Technology Research and Development Program of Shaanxi Province, China (2011KJXX63)
文摘This study aimed to determine the characteristics of soil microbial community composition and its relationship with soil chemical properties during natural recovery in the Loess Plateau.The soil microbial community composition was analyzed by comparing the soil microbial phospholipid fatty acids（PLFAs） of eight croplands abandoned for 1,3,5,10,13,15,20,and 30 yr in the Dunshan watershed,northern Loess Plateau,China.The results showed that soil organic carbon,total nitrogen,soil microbial biomass carbon,and soil microbial biomass nitrogen significantly increased with the abandonment duration,whereas the metabolic quotient significantly decreased.The Shannon richness and Shannon evenness of PLFAs significantly increased after 10 yr of abandonment.Gram-negative,Gram-positive,bacterial,fungal,and total PLFAs linearly increased with increased abandonment duration.Redundancy analysis showed that the abandonment duration was the most important environmental factor in determining the PLFA microbial community composition.The soil microbial PLFAs changed from anteiso-to iso-,unsaturated to saturated,and short-to long-chain during natural recovery.Therefore,in the Loess Plateau,cropland abandonment for natural recovery resulted in the increase of the soil microbial PLFA biomass and microbial PLFA species and changed the microbial from chemolithotrophic to a more heterotrophic community.
基金supported by the Basic Scientific Research Fund of Karst Geological Institute (No. 2012012)the Natural Science Fund Project of Guangxi (Nos. 2013GXNSFBA019218, 2013GXNSFBAO19217)the Project of the China Geological Survey (Nos. 12120113052500, 12120113005200)
文摘Arsenic （As） pollutants generated by human activities in karst areas flow into subterranean streams and contaminate groundwater easily because of the unique hydrogeological characteristics of karst areas. To elucidate the reaction mechanisms of arsenic in karst subterranean streams, physical-chemical analysis was conducted by an inductively coupled plasma mass spectrometer and an X-ray fluorescence spectrometer. The results show that inorganic species account for most of the total arsenic, whereas organic arsenic is not detected or occurs in infinitesimal amounts. As（III） accounts for 51.0% ± 9.9% of the total inorganic arsenic. Arsenic attenuation occurs and the attenuation rates of total As, As（III） and As（V） in the Lihu subterranean stream are 51%, 36% and 59%, respectively. To fully explain the main geochemical factors influencing arsenic attenuation, SPSS 13.0 and CANOCO 4.5 bundled with CanoDraw for Windows were used for simple statistical analysis and redundancy analysis （RDA）. Eight main factors, i.e., sediment iron （SFe）, sediment aluminum （SAI）, sediment calcium （SCa）, sediment organic matter （SOM）, sediment manganese （SMn）, water calcium （WCa^2＋）, water magnesium （WMg^2＋）, and water bicarbonate ion （WILCOX） were extracted from thirteen indicators. Their impacts on arsenic content rank as： SFe〉SCa〉WCa^2＋〉SAl〉wHCO3^-〉SMn〉SOM〉WMg^2＋. Of these factors, SFe, SAl, SCa, SOM, SMn, WMg^2＋ and WCa＆2＋ promote arsenic attenuation, whereas WHCO3^- inhibits it. Further investigation revealed that the redox potential （Eh） and pH are adverse to arsenic removal. The dramatic distinction between karst and non-karst terrain is that calcium and bicarbonate are the primary factors influencing arsenic migration in karst areas due to the high calcium concentration and alkalinity of karst water.
