Nitrogen Abundances Research Articles

The Isotopic Ecology of the Mammoth Steppe

The Mammoth Steppe was the dominant terrestrial biome of the Northern Hemisphere during the late Pleistocene. It encompassed a nonanalog community of animals living in a cold and treeless steppe-tundra landscape. The high diversity of species, including megafauna, could be supported by a productive environment. The carbon-13 and nitrogen-15 abundances in bone collagen confirmed that the coexistence of the large herbivores was facilitated by a pronounced dietary niche partitioning, with some species relatively flexible in the exploitation of browse and graze, while others were more specialized. The isotopic abundances of carbon and nitrogen in carnivores confirm a dietary partitioning, probably based on the size of prey, with an increasingly generalist behavior emerging after the Last Glacial Maximum with notable exceptions. Isotopic investigation reveals dynamic processes of ecological displacement and replacement, shedding new light on the potential niche spectrum of extant species that are now present as relic populations. ▪ The Mammoth Steppe is an extinct nonanalog ecosystem with high productivity and biodiversity despite the cold and dry conditions of the Last Glacial Period. ▪ Stable isotopes reveal that niche partitioning among herbivores and carnivores is a dominant trait of the Mammoth Steppe. ▪ Switches in preferred prey and ecological replacement are observed among carnivores over time, with the few highly specialized predators going extinct. ▪ Warmer and more humid conditions preceding the Holocene impacted large herbivores in most regions of the Mammoth Steppe, driving some of the largest ones to extinction.

Comparison of soil chemical and microbial properties in monoculture larch and mixed plantations in a temperate forest ecosystem in Northeast China

BackgroundThe introduction of broadleaved tree species in monoculture larch plantations to establish mixed plantations is a feasible way to improve soil properties. However, our understanding of how mixed plantations of larch and broadleaved tree species affect soil properties, particularly microbial community structures and functions, remains limited. We compared three paired monoculture larch (Larix gmelinii) and mixed [L. gmelinii–Fraxinus mandshurica (a dominant broadleaved species)] plantations to investigate the effect of a larch–broadleaved tree species combination on the carbon (C) and nitrogen (N) content, abundance and composition of microbial communities, and enzyme activities associated with litter and soil.ResultsThe bacterial abundance in the litter, soil N availability, pH and electronic conductivity were significantly higher in the mixed-species plantation in comparison with those of the monoculture plantation. However, in the litter of mixed-species plantation, the relative levels of Agaricomycetes fungi were lower than those of the monoculture plantation, indicating that soil fungal communities were affected more than bacterial communities. In contrast, soil in the mixed-species plantation showed increased exoglucanase and N-acetyl-β-glucosaminidase activities. However, the C and N levels, δ13C and δ15N values, and fungal abundance in litter and soil were not significantly different between the monoculture and mixed-species plantations.ConclusionsOur findings suggest that fungal community compositions and enzyme activities are sensitive to the introduction of broadleaved tree species into larch plantations. Thus, these parameters can be used as important indicators to evaluate the effects of tree species selection on soil restoration.

Candida tropicalis prompted effectively simultaneous removal of carbon, nitrogen and phosphorus in activated sludge reactor: Microbial community succession and functional characteristics

A new Candida tropicalis that simultaneously remove nitrogen and phosphorus, and degrade organic matters was isolated. Three continuous stirred tank reactors inoculated with C. tropicalis, activated sludge, and their co-existing system in aerobic condition were operated for 150 days. Results demonstrated that the inoculation of C. tropicalis in the co-existing system remarkably improved the carbon, nitrogen, and phosphorus removal efficiencies. The co-existing system had increased carbon, nitrogen, and phosphorus removal efficiencies (92%, 73%, and 63%, respectively); decreased biomass (reduced from 1200 mg/L to 500 mg/L); and C. tropicalis as the dominant strain. The relative abundance of traditional nitrogen- and phosphorus-removing microorganisms, such as Mycobacterium, Flavonifactor, and Devsia, increased in the co-existing system. Metagenomic analysis showed that the presence of the PCYT2, EPT1, and phnPP genes and more complexed metabolism pathways in the co-existing system might be responsible for the more activated metabolism process.

Gaia-ESO Survey: Detailed elemental abundances in red giants of the peculiar globular cluster NGC 1851

Context. NGC 1851 is one of several globular clusters for which multiple stellar populations of the subgiant branch have been clearly identified and a difference in metallicity detected. A crucial piece of information on the formation history of this cluster can be provided by the sum of A(C+N+O) abundances. However, these values have lacked a general consensus thus far. The separation of the subgiant branch can be based on age and/or A(C+N+O) abundance differences. Aims. Our main aim was to determine carbon, nitrogen, and oxygen abundances for evolved giants in the globular cluster NGC 1851 in order to check whether or not the double populations of stars are coeval. Methods. High-resolution spectra, observed with the FLAMES-UVES spectrograph on the ESO VLT telescope, were analysed using a differential model atmosphere method. Abundances of carbon were derived using spectral synthesis of the C2 band heads at 5135 and 5635.5 Å. The wavelength interval 6470−6490 Å, with CN features, was analysed to determine nitrogen abundances. Oxygen abundances were determined from the [O I] line at 6300 Å. Abundances of other chemical elements were determined from equivalent widths or spectral syntheses of unblended spectral lines. Results. We provide abundances of up to 29 chemical elements for a sample of 45 giants in NGC 1851. The investigated stars can be separated into two populations with a difference of 0.07 dex in the mean metallicity, 0.3 dex in the mean C/N, and 0.35 dex in the mean s-process dominated element-to-iron abundance ratios [s/Fe]. No significant difference was determined in the mean values of A(C+N+O) as well as in abundance to iron ratios of carbon, α- and iron-peak-elements, and of europium. Conclusions. As the averaged A(C+N+O) values between the two populations do not differ, additional evidence is given that NGC 1851 is composed of two clusters, the metal-rich cluster being by about 0.6 Gyr older than the metal-poor one. A global overview of NGC 1851 properties and the detailed abundances of chemical elements favour its formation in a dwarf spheroidal galaxy that was accreted by the Milky Way.

A nitrogen-rich atmosphere on ancient Mars consistent with isotopic evolution models

The ratio of nitrogen isotopes in the Martian atmosphere is a key constraint on the planet's atmospheric evolution. However, enrichment of the heavy isotope expected due to atmospheric loss from sputtering and photochemical processes is greater than measurements. A massive, multi-bar early CO2-dominated atmosphere and recent volcanic outgassing have been proposed to explain this discrepancy, and many previous models have assumed atmospheric nitrogen rapidly reached a steady state where loss to space balanced volcanic outgassing. Here we show using time-dependent models that the abundance and isotopic composition of nitrogen in the Martian atmosphere can be explained by a family of evolutionary scenarios in which the initial partial pressure of nitrogen is sufficiently high that a steady state is not reached and nitrogen levels gradually decline to present-day values over 4 billion years. Our solutions do not require a multi-bar early CO2 atmosphere and are consistent with volcanic outgassing indicated by both geologic mapping and the atmospheric 36Ar/38Ar ratio. Monte Carlo simulations that include these scenarios estimate that the partial pressure of N2 was 60 - 740 mbar (90% confidence, with a median value of 310 mbar) at 3.8 billion years ago when the valley networks formed. We suggest that such a high nitrogen partial pressure could have contributed substantially to warming on early Mars.

Isotopic and biogenic silica evidence for eutrophic conditions in South China during the Frasnian-Famennian biotic crisis

The Late Devonian Frasnian-Famennian (F F) transition at ca. 367 Ma was a key event in Phanerozoic Eon involving a massive biotic crisis, which coincided with a positive carbon isotope anomaly and large climate changes associated with eustatic fluctuations. The details underpinning the initiation of the mass extinction, however, remain problematic. To better understand this scientific issue, we conducted a time series of biogeochemical studies that included C N isotopes and biogenic silica (BSi) from the F F transition in the Yangdi section, South China. The carbon isotope data accurately constrain the Upper Kellwasser Horizon (UKH) and Lower Kellwasser Horizon (LKH) in this section. A short-term decrease in carbon isotope fractionation in the F F transition indicates a decreased p CO 2 level in the LKU and UKH, while the increased fractionation in the uppermost UKH was caused by the rapidly negative δ 13 C org excursion, likely as the result of enhanced inputs from chemoautotrophs. On the other hand, the nitrogen isotope data suggest that the surface water had limited availability of dissolved N before and after the F F boundary due to enhanced benthic denitrification; these conditions led to a supply of external nitrogen that was likely driven by persistent diazotrophy. Increased sedimentary δ 15 N (up to +7.3‰) during the UKH suggests a rapidly amplified nitrate pool associated with water column denitrification, implying intensification of marine productivity and expansion of dysoxic-anoxic conditions linked to intensified oceanic circulation. In addition, BSi in sediments has the potential to evaluate historic changes in primary productivity of oceans and the maxima of BSi mass values (up to 1.96%) are clearly documented in the upper part of the UKH. Insofar as the elevated abundance of biolimited nitrogen coincided with strongly increased marine phytoplankton productivity at the F F boundary, we speculate that the nutrient-driven eutrophic conditions in surface waters associated with attendant redox changes may have been the main killing mechanism in the mass extinction. • The cooling event in the UKH coincided with declined △ 13 C and elevated δ 15 N. • We attribute the low δ 15 N values to enhanced microbial nitrogen fixation. • Sedimentary δ 15 N increases are indicative of an amplified N pool. • Siliceous organism blooms are consistent with positive δ 13 C carb and δ 15 N shifts. • The F F crisis was likely the result of eutrophication in shallow water.

A hydroponic plants and biofilm combined treatment system efficiently purified wastewater from cold flowing water aquaculture

Recently, more and more cold flowing water aquaculture has been adopted, but its wastewater treatment is always ignored, which causes great pressure on the environment. In this study, a compound in-situ treatment system that applied hydroponic plants and biofilm was constructed to treat the wastewater produced by cold flowing water culture of sturgeon. The removal efficiency of the nutrients from culture and the microbial composition in water and biofilm were tested, the correlation between the water quality indexes and bacterium was analyzed, and the abundance of nitrogen and phosphorus cycling genes was quantified. The results show that the system respectively achieved 90%, 100%, 100%, 100% and 48% removal efficiency of NH4+-N, NO3−-N, TN, TP and COD which were produced by experimental sturgeon culture. Chinese cabbage (Brassica rapa var. chinensis) and water dropwort (Oenanthe javanica) showed obvious growth in the four plants, which contributed to the removal of nutrients from wastewater. Besides, in the biofilm, Proteobacteria, Bacteroidetes and Verrucomicrobia became the top three dominant flora at the phylum level, and Flavobacterium, Rhodoferax, Sphaerotilus and Chitinimonas became the top four dominant flora at the genus level, which promoted the removal of nitrogen in the wastewater. The FAPROTAX analysis result shows that the highest functions within the carbon and nitrogen metabolisms were significantly identified in the biofilm, such as chemoheterotrophy, aerobic chemoheterotrophy and nitrate reduction. Further, the abundance of denitrifying genes (narG and napA) was higher than the nitrifying related genes (nxrB and amoA), indicating the more active denitrifying process. In summary, the compound in-situ treatment system efficiently removed nutrients from cold flowing water aquaculture. And the combined purification of hydroponic plants and biofilm which is rich in denitrifying bacterium plays an essential role in this process.

Application of a Mechanistic Model for the Prediction of Microcystin Production by Microcystis in Lab Cultures and Tropical Lake.

Microcystin is an algal toxin that is commonly found in eutrophic freshwaters throughout the world. Many studies have been conducted to elucidate the factors affecting its production, but few studies have attempted mechanistic models of its production to aid water managers in predicting its occurrence. Here, a mechanistic model was developed based on microcystin production by Microcystis spp. under laboratory culture and ambient field conditions. The model was built on STELLA, a dynamic modelling software, and is based on constitutive cell quota that varies with nitrogen, phosphorus, and temperature. In addition to these factors, varying the decay rate of microcystin according to its proportion in the intracellular and extracellular phase was important for the model’s performance. With all these effects, the model predicted most of the observations with a model efficiency that was >0.72 and >0.45 for the lab and field conditions respectively. However, some large discrepancies were observed. These may have arisen from the non-constitutive microcystin production that appear to have a precondition of nitrogen abundance. Another reason for the large root mean square error is that cell quota is affected by factors differently between strains.

Environmental stress-discriminatory taxa are associated with high C and N cycling functional potentials in dryland grasslands

Increasing environmental stress strongly affects soil microbial communities, but the responses of the microbial assembly and the functional potential of the dominant microbial community in the presence of environmental stress in drylands are still poorly understood. Here, we undertook a broad appraisal of the abundance, diversity, similarity, community assembly, network properties and functions of soil microbiomes in 82 dryland grasslands along environmental gradients. We found that the bacterial and fungal diversity and community similarity showed different sensitivities to environmental stress (decreased mean annual precipitation (MAP) and soil nutrient levels and increased soil pH), and MAP was the most important factor influencing microbial community patterns. In addition, the dominant subcommunity of both bacteria and fungi was more sensitive to environmental stress than the nondominant subcommunity. Although increasing environmental stress decreased microbial phylogenetic clustering, it had no effects on the stochastic and deterministic assembly process balance. Moreover, we identified 101 bacterial and 34 fungal environmental stress-discriminatory taxa that were sensitive to environmental stress, and these bacterial markers showed a high correlation with the abundance of carbon (C) and nitrogen (N) cycling-related genes, whereas the taxa classified as connectors in the network were mainly correlated with C degradation genes. Our study shows that the different responses of bacteria and fungi to environmental stress bring challenges to predicting microbial function, but a relatively small number of taxa play an important role in driving C and N cycling-related functional genes, indicating that identifying an organism's phenotypic characteristics or traits of key taxa may improve our knowledge of the microbial response to ongoing global changes.

Gas phase Elemental abundances in Molecular cloudS (GEMS)

Gas phase Elemental abundances in Molecular CloudS (GEMS) is an IRAM 30m Large Program aimed at determining the elemental abundances of carbon (C), oxygen (O), nitrogen (N), and sulphur (S) in a selected set of prototypical star forming filaments. Elemental abundances have a key role in the star formation process by driving the gas cooling rate and the gas ionization degree. Defining elemental abundance as the amount of a given atom in volatiles, the elemental abundances of C, O, and N in the interstellar medium are currently known within a factor of a few. However, the elemental abundance of S remains uncertain by several orders of magnitude, and its determination is one of the most challenging goals of this program. This is a review of the observational, theoretical, and modeling effort that GEMS team is doing to improve our knowledge of the sulphur chemistry. Our results suggest that the sulphur elemental abundance depends on the local physical conditions and the star formation activity in the environment.

Composition of Diamond from the 95-2 Pipe, Lake Timiskaming Kimberlite Cluster, Superior Craton, Canada

ABSTRACT Forty-one samples of diamond from the Jurassic 95-2 kimberlite pipe in the Lake Timiskaming Kimberlite Cluster, Superior Craton, Canada, were imaged using cathodoluminescence and analyzed by secondary ion mass spectrometry and Fourier-transform infrared absorbance spectrometry to determine carbon stable isotope composition, total nitrogen abundance, and nitrogen aggregation state. The carbon isotope compositions results (δ13CVPDB) range from –9.11 to –3.57‰, with a mean value of –5.8‰. Intra-stone variation is small (maximum ∼2.2‰, and in most individual diamond samples <1‰). Nitrogen contents range from 0.5 to 2040 ppm (mean of 483 ppm). The greatest range of values in a single stone is 825 ppm. The samples are poorly aggregated in terms of nitrogen. The samples are mostly type IaA or IaAB, with a few bordering on type Ib. Diamond growth was episodic, with nitrogen behaving highly compatibly (i.e., D = [N]diamond/[N]fluid >> 1). Precipitation was likely from a carbonate-rich fluid in a peridotitic (lherzolitic) environment within the mantle of the central Superior Craton. This generation of diamond growth is very similar to those reported from the Jurassic age Victor and U2 pipes of the Attawapiskat Kimberlite Cluster, and distinct from a possibly much older (>1.1 Ga) generation of diamond reported in other older host rocks (T1, Wawa, Lynx, and Renard). This older generation of diamond at these other localities is also predominantly of the peridotitic (harzburgitic) paragenesis but contains far less nitrogen (although typically more aggregated as B centers) and has higher δ13CVPDB. The younger generation of diamond formed after mantle heating during formation of the Mid-Continental Rift (ca. 1.1 Ga) destroyed any proximal prior generation(s) of diamond. Igneous activity after 1.1 Ga subsequently refertilized the cratonic mantle to a lherzolitic paragenesis in which the younger generation precipitated.

Impact of sedimentation, climate and sea level on marine sedimentary pyrite sulfur isotopes: Insights from the Valle di Manche section (Lower-Middle Pleistocene, southern Italy)

Variations in the isotopic composition of sulfur in sedimentary pyrite (δ34Spyr) are often used to reconstruct global sulfur biogeochemical cycling and Earth's surface oxidation state over Earth history. Recent work, however, has shown that δ34Spyr is strongly impacted by local depositional conditions, which both confounds attempts to reconstruct global sulfur cycling and provides a new proxy for investigating local paleoenvironmental conditions. We present a chemostratigraphic record of δ34Spyr in a detailed paleoenvironmental and sequence stratigraphic framework spanning the Early-Mid Pleistocene transition from the Crotone Basin (Calabria, Southern Italy). Bulk δ34Spyr data parallel transgressive-regressive cycles and enable the differentiation of progradational and retrogradational stacking patterns, where δ34Spyr values decrease toward −50‰ in outer shelf deposits during late transgression and become more positive and variable in prograding sedimentary units accumulated in shallower environments. In parallel with the observed variations in δ34Spyr, complementary data on organic carbon abundance and isotopic composition and total nitrogen abundance document changes in terrestrial delivery of sediment to the basin, as a consequence of glacial-interglacial eustatic sea-level changes, regional climate and local tectonics. The chemostratigraphic record of δ34Spyr appears sensitive to variations in sedimentation rates and local erosional surfaces and therefore may represent a powerful tool to assess stratal stacking patterns for sequence stratigraphic interpretations of siliciclastic successions. These results highlight the role of local conditions in controlling sedimentary δ34Spyr records and illustrate how isotopic data can be used to reconstruct key parameters of the sedimentary environment that might not otherwise be accessible, especially in deep-time strata.

DETECTION OF NITROGENASE PRODUCING BACTERIA FROM THE SOIL OF LIWA BOTANICAL GARDEN

Liwa Botanical Gardens is an ex-situ conservation area for various types of plants. Each plant produces organic matter that will provide nutrients for the growth of nitrogen-fixing bacteria. This indicates the existence of an environment that supports the growth of nitrogen-fixing bacteria. Nitrogen is one of the nutrients needed by plants for their growth. However, the abundance of nitrogen in the atmosphere cannot be utilized directly by plants but needs to transform into ammonium and nitrate first. This transformation can be done by nitrogen-fixing bacteria through an enzymatic process. This research aims to obtain bacterial isolates that can fix nitrogen. Nitrogen-fixing bacteria were isolated using Nutrient Agar (NA) medium and furthered by nitrogenase activity detection test with semi-solid Nitrogen Free Bromothymol Blue (NFB). Nitrogen-fixing bacteria are characterized by color changes in the medium. The results obtained 22 isolates with 3 isolates detected capable of producing nitrogenase enzymes, namely TBP B3, TB1 B2, and TMA2 B2.

Impact of Plasma-Activated Water (PAW) on Seed Germination of Soybean

The present study reports the generation of plasma-activated water (PAW) using dielectric barrier discharge (DBD), its physicochemical properties, and its potential impact on the seed germination and seedling growth of soybean. The results revealed significant changes in physical parameters, such as pH, total dissolved solids, total suspended solids, turbidity, conductivity, dissolved oxygen, and chemical parameters, such as calcium, chromium, sodium, manganese, nitrate, nitrites, phosphorus, and sulfur and biological parameter such as E. coli in water after plasma treatment. The concentration of dissolved oxygen, conductivity, nitrate, nitrite, and sulfur was increased with an increase in water treatment time, and the amounts of the other analyzed parameters decreased with the increase in water treatment time. The effects of untreated water and plasma-activated water treated for 20 minutes on soybean germination and growth were studied. The germination rate was found to be higher with plasma-treated water. Shoot lengths, seedlings length, vigor index, and germination rates were increased as compared to those germinated by normal water irrigation. The seedlings irrigated with PAW responded to the abundance of nitrogen by producing intensely green leaves because of their increased chlorophyll a as compared to seedlings irrigated with normal water. However, the content of chlorophyll b and carotenoids was found to decrease in the case of seedlings irrigated with PAW. Based on this report, we conclude that PAW could be used to substantially enhance seed germination and seedling growth.

The solar carbon, nitrogen, and oxygen abundances from a 3D LTE analysis of molecular lines

Carbon, nitrogen, and oxygen are the fourth, sixth, and third most abundant elements in the Sun. Their abundances remain hotly debated due to the so-called solar modelling problem that has persisted for almost 20 years. We revisit this issue by presenting a homogeneous analysis of 408 molecular lines across 12 diagnostic groups, observed in the solar intensity spectrum. Using a realistic 3D radiative-hydrodynamic model solar photosphere and local thermodynamic equilibrium (LTE) line formation, we find log ϵC = 8.47 ± 0.02, log ϵN = 7.89 ± 0.04, and log ϵO = 8.70 ± 0.04. The stipulated uncertainties mainly reflect the sensitivity of the results to the model atmosphere; this sensitivity is correlated between the different diagnostic groups, which all agree with the mean result to within 0.03 dex. For carbon and oxygen, the molecular results are in excellent agreement with our 3D non-LTE analyses of atomic lines. For nitrogen, however, the molecular indicators give a 0.12 dex larger abundance than the atomic indicators, and our best estimate of the solar nitrogen abundance is given by the mean: 7.83 dex. The solar oxygen abundance advocated here is close to our earlier determination of 8.69 dex, and so the present results do not significantly alleviate the solar modelling problem.

Co-analysis of rhizosphere metabolomics and bacterial community structures to unfold soil ecosystem health in Camellia oleifera land under long-term cultivation

Long-term cultivation of woody species would change soil microbial community and metabolites composition, and then affect soil ecological function. Camellia oleifera is an important economically cultivar grown in subtropical regions of China but its effect on soil quality and health remains unclear. Soil bacterial communities and metabolome composition are investigated in this study via high-throughput sequencing and soil metabolomics to determine soil quality under different growth stages (sapling, maturity, and degeneration periods) of C. oleifera. Main results revealed that soil metabolite composition reaches equilibrium faster than microorganisms. Higher carbohydrate content (such as trehalose, mannopyranose, and sucrose) during degeneration stages of C. oleifera induces the decrease of Chloroflexi and Actinobacteria abundances and results in lower disease resistance potential than that of sapling and mature stages. Long-term cultivation of C. oleifera soil showed significantly higher abundance of carbon, nitrogen, and phosphorus metabolism, and presented significantly higher soil organic matter, available nitrogen, and available phosphorus contents. Results demonstrated that long-term C. oleifera cultivation can significantly improve soil fertility but potentially cause the decline of soil ecological health.

Insights into the synergy between functional microbes and dissolved oxygen partition in the single-stage partial nitritation-anammox granules system

The rapid start-up and stable operation of the single-stage partial nitritation-anammox (PNA) process remains a challenge in practical applications. An integrated investigation of nitrogen removal performance, sludge characteristics, activity and abundance, and microbial dynamics was implemented for 360 days via an airlift internal circulation reactor. During long-term operation, the reactor realized a stable dissolved oxygen (DO) partition and cultivated granular sludge. The nitrogen removal rate increased from 0.15 kg-N/m3/d to 1.24 kg-N/m3/d, and a high nitrogen removal efficiency of 82.6% was obtained. A stable DO partition further accelerated the bioreaction rates and enhanced the activity of functional microbes. The activities of ammonia oxidation and anammox reached 1.21 g-N/g-VSS/d and 1.43 g-N/g-VSS/d, respectively. Sludge granulation efficiently enriched the abundances of Candidatus Brocadia (7.4%) and Nitrosomonas (5.2%). These results demonstrated that efficient DO partition and stable culture of granular sludge could enhance the synergy of functional microbes for autotrophic nitrogen removal.

Biochar and nitrogen fertilizer increase Glomus synergism and abundance and promote Trifolium pratense growth while inhibiting pollutant accumulation

We examined the effects of nitrate nitrogen fertilizer (N), biochar (BC) and arbuscular mycorrhizal fungi (AMF) on Trifolium pratense mycorrhizal colonization, dry mass, nutrient and pollutant accumulation and soil AMF community, aiming to determine a potential approach that is beneficial to clover growth and AMF community under contaminated environment. Result showed that soil pH increased from 6.88 to 7.01 in the presence of N in combination BC treatments. Compared to control, N in combination BC treatments significantly decreased DTPA-Zn, Pb, Cd, As and Cu concentrations, and the average reduction for DTPA-Zn, Pb, Cd, As and Cu concentration by 53.2, 52.5, 48.8, 44.5 and 45.5%, respectively. Root colonization, shoot and root dry masses were increased when receiving both N and BC. On average, the shoot P, Zn, Pb, Cd and As levels were reduced by 39.7, 62.4, 86.7, 84.6 and 87.8% when receiving both N and BC and simultaneously the root Cd and Zn concentrations were reduced by 64.9 and 55.8%, respectively. DTPA-extractable Cd, Zn and Pb were positively correlated to shoot Zn, Pb and Cd concentrations as well as root Zn and Cd concentrations but negatively correlated with pH. Moreover, Glomus species were the soil major AMF present with all treatments. The combination N and BC treatments increased Glomus abundance but did not affect overall AMF diversity. Soil pH, DTPA-Cd, Zn, Pb and Cu had greater effect on AMF community structure as assessed by redundancy analysis (RDA). Glomus abundance was positively related to pH, root colonization, shoot and root dry mass and negatively related to DTPA-Cd, Zn, Pb and Cu. A network analysis indicated that BC and N addition promoted synergistic interactions among Glomus species. Our results demonstrated that the N in combination BC treatments can promote plant growth while decreasing pollutant accumulation in shoot and root, and the N and BC addition can increase Glomus abundance and their synergistic interactions under multi-contaminated soil.

The effect of Haemonchus contortus and Trichostrongylus colubriforms infection on the ruminal microbiome of lambs

We evaluated Haemonchus contortus (HC) and Trichostrongylus colubriformis (TC) infection on the ruminal microbial community of Santa Ines lambs to better understand the pathophysiology of parasite infections and the interactions among gastrointestinal nematodes and gut resident microbiota. In this study, 18 six months of age lambs were maintained for 34 days in individual pens divided into three treatments that included animals infected with HC and TC, and control (infection-free). Haematological, ruminal parameter and microbial nitrogen absorbed by pune derivatives, as well as enteric methane emission (CH4), were analysed, and the rumen microbial taxonomic and functional profile assessed by shotgun metagenomics. The analysis showed that total protein, albumin, urea, and butyrate level were lower in animals infected by both parasites, while HC infection also decreased the haemoglobin level. Both infected groups (TC and HC) increased the enteric methane emission (CH4). TC and HC infections increased the diversity and richness of functional microbial genes. Most alterations in the rumen microbiome composition of infected groups are associated with the suppression of microbes involved in microbial homeostasis maintenance and expansion of the archaeal community in the infected animals. Infection led to an increased abundance of nitrogen, amino acid, protein, and energy metabolism genes. Overall, TC and HC infection increased the enteric methane emission, negatively affected taxon's responsible for maintenance de rumen homeostasis and modulated some important genes related to protein and energy metabolism.

Estimation of ages and masses via carbon and nitrogen abundances for 556 007 giants from LAMOST

Estimating ages for a large number of giants is of great importance for studying Galactic evolution. In this work, we determine stellar ages and masses for 556 007 giants from LAMOST Data Release 5 (DR5) with empirical relations estimated from chemical [C/N] abundance ratios. Our sample reveals the two well-known sequences in the age–[α/M] relation. The high-α sequence is composed of stars older than 8 Gyr and low-α sequence is composed of stars with age ranging from 0 Gyr to 13.8 Gyr. Our sample also shows a flat age–[M/H] relation up until 12 Gyr. We compare these distributions with Galactic Chemical Evolution models for reference. When looking at the spatial distribution of stars in 2 Gyr age bins, we find that young stars are concentrated towards the Galactic plane and older stars extend to higher height above and below the disk. We find a smooth transition of median Galactic height for different age bins, which suggests a strong age-dependence on Galactic scale height.