Search

Fine particulate matter (PM2.5) is a risk factor of cardiovascular disease. Associations between PM2.5 compositions and cardiovascular disease are a point of special interest but inconsistent. This study aimed to explore the cardiovascular effects of heavy metal(loid) compositions in PM2.5. Data for mortality, air pollutants and meteorological factors in Anyang, China from 2017 to 2021 were collected. Heavy metal(loid) in PM2.5 were monitored and examined monthly. A Case-crossover design was applied to the estimated data set. The interquartile range increase in cadmium (Cd), antimony (Sb) and arsenic (As) at lag 1 was associated with increment of 8.1% (95% CI: 3.3, 13.2), 4.8% (95% CI: 0.2, 9.5) and 3.5% (95% CI: 1.1, 6.0) cardiovascular mortality. Selenium in lag 2 was inversely associated with cerebrovascular mortality (RR = 0.920 95% CI: 0.862, 0.983). Current-day exposure of aluminum was positively associated with mortality from ischemic heart disease (RR = 1.083 95% CI: 1.001, 1.172). Stratified analysis indicated sex, age and season modified the cardiovascular effects of As (P < 0.05). Our study reveals that heavy metal(loid) play key roles in adverse effects of PM2.5. Cd, Sb and As were significant risk factors of cardiovascular mortality. These findings have potential implications for accurate air pollutants control and management to improve public health benefits. [ABSTRACT FROM AUTHOR]

To adapt to the complex belowground environment, plants make trade-offs between root resource acquisition and defence ability. This includes forming partnerships with different types of root associating microorganisms, such as arbuscular mycorrhizal and ectomycorrhizal fungi. These trade-offs, by mediating root chemistry, exert legacy effects on nutrient release during decomposition, which may, in turn, affect the ability of new roots to re-acquire resources, thereby generating a feedback loop. However, the linkages at the basis of this potential feedback loop remain largely unquantified. Here, we propose a trait-based root 'acquisition-defence-decomposition' conceptual framework and test the strength of relevant linkages across 90 angiosperm tree species. We show that, at the plant species level, the root-fungal symbiosis gradient within the root economics space, root chemical defence (condensed tannins), and root decomposition rate are closely linked, providing support to this framework. Beyond the dichotomy between arbuscular mycorrhizal-dominated versus ectomycorrhizal-dominated systems, we suggest a continuous shift in feedback loops, from 'high arbuscular mycorrhizal symbiosis-low defence-fast decomposition-inorganic nutrition' by evolutionarily ancient taxa to 'high ectomycorrhizal symbiosis-high defence-slow decomposition-organic nutrition' by more modern taxa. This 'acquisition-defence-decomposition' framework provides a foundation for testable hypotheses on multidimensional linkages between species' belowground strategies and ecosystem nutrient cycling in an evolutionary context. This work on 90 angiosperm tree species presents a trait-based root 'acquisition-defence-decomposition' framework. In support, the study shows how tree root economics strategy and mycorrhizal strategy strongly correlate with root litter chemical defences that define root decomposability, with multiple potential consequences feeding back on tree nutrition. [ABSTRACT FROM AUTHOR]

Excessive fluoride can adversely affect bone mineral density (BMD). Oxidative stress and mitochondrial dysfunction are crucial mechanisms of health damage induced by fluoride. Here, a cross-sectional survey involving 907 Chinese farmers (aged 18–60) was carried out in Tongxu County in 2017, aiming to investigate the significance of mitochondrial DNA copy number (mtDNAcn) and oxidative stress in fluoride-related BMD change. Concentrations of urinary fluoride (UF), serum oxidative stress biomarkers, including total antioxidant capacity (T-AOC), total superoxide dismutase (T-SOD), glutathione peroxidase (GSH-Px), and malondialdehyde (MDA), as well as relative mtDNAcn in peripheral blood were determined. The multivariable linear model and mediation analysis were performed to assess associations between UF, oxidative stress, and relative mtDNAcn with BMD. Results showed that GSH-Px levels increased by 6.98 U/mL [95% confidence interval (CI) 3.41–10.56)] with each 1.0 mg/L increment of UF. After stratification, the T-AOC, relative mtDNAcn, and BMD decreased by 0.04 mmol/L (–0.08 ~ –0.01), 0.29-unit (–0.55 ~ –0.04), and 0.18-unit (–0.33 ~ –0.03) with every 1.0 mg/L elevation of UF in the excessive fluoride group (EFG, adults with UF > 1.6 mg/L), respectively. Furthermore, T-AOC and relative mtDNAcn were favorably related to the BMD in the EFG (β = 0.82, 95%CI 0.16–1.48 for T-AOC; β = 0.11, 95%CI 0.02–0.19 for relative mtDNAcn). Mediation analysis showed that relative mtDNAcn and T-AOC mediated 15.4% and 17.1% of the connection between excessive fluoride and reduced BMD, respectively. Findings suggested that excessive fluoride was related to lower BMD in adults, and the decrement of T-AOC and relative mtDNAcn partially mediate this relationship. [ABSTRACT FROM AUTHOR]

Due to a wide variety and similar physicochemical properties of monohydroxy saturated fatty acids (OH-FAs) isomers as biomarkers, previously reported OH-FAs in environmental samples were mainly restricted to the α-, β-, (ω-1)- and ω-OH-FA isomers. Here, N,N-dimethylethylenediamine (DMED) labeling coupled with ultra-high-performance liquid chromatography-mass spectrometry (UHPLC-MS) analysis with multiple reaction monitoring mode (MRM) was developed to screen, identify and quantify position-specific isomers of OH-FAs (C8-C18). An identification strategy of positional isomers of OH-FAs, including α-, β-, 4 to (ω-2)-, (ω-1)- and ω-OH-FAs, was established by integrating the characteristics of peak intensity ratios of product ions based on the library of OH-FAs. Meanwhile, d4-DMED-labeled OH-FA standards as internal standards were adopted for the relative quantification of positional isomers. The extraction processes were optimized for different interface-environmental samples. Our method offers a promising tool to investigate position-specific isomers of OH-FAs in the land-atmosphere interface. [ABSTRACT FROM AUTHOR]

Electrochemical conversion of abundant carbon- and nitrogen-containing small molecules into high-valued organonitrogen compounds is alluring to reducing current dependence on fossil energy. Here we report a single-cell electrochemical oxidation approach to transform methanol and ammonia into formamide under ambient conditions over Pt electrocatalyst that provides 74.26% selectivity from methanol to formamide and a Faradaic efficiency of 40.39% at 100 mA cm−2 current density, gaining an economic advantage over conventional manufacturing based on techno-economic analysis. A 46-h continuous test performed in the flow cell shows no performance decay. The combined results of in situ experiments and theoretical simulations unveil the C–N bond formation mechanism via nucleophilic attack of NH3 on an aldehyde-like intermediate derived from methanol electrooxidation. This work offers a way to synthesize formamide via C–N coupling and can be extended to substantially synthesize other value-added organonitrogen chemicals (e.g., acetamide, propenamide, formyl methylamine). Developing a sustainable manufacturing method using biomass-derived feedstock at ambient conditions is highly desirable. Here the authors report electrooxidation route for synthesis of formamide from methanol and ammonia in water [ABSTRACT FROM AUTHOR]

Key message: Chinese fir has strong transpiration and assimilation activity. Daily stem radial increments were closely related to moisture conditions. Tree growth responds to a climate in similar ways but with different magnitudes. High temporal resolution dendrometric measurements offer a great opportunity to acquire valuable information about stem size dynamics at half-hour intervals and improve our understanding of climate influence on tree growth and physiological processes. In the present study, we continuously monitored intra-annual stem radial size changes with the help of automated dendrometers in pure Masson pine and Chinese fir forests widely distributed in subtropical China across two consecutive years of 2017 and 2018. The main goal of this study was to analyze intra-annual stem growth dynamics as well as their climatic forcing. Our results indicate a similar growth onset between Masson pine and Chinese fir but prolonged growth duration for Chinese fir in 2018. Large stem-size fluctuations with particularly strong stem shrinkage especially in summer were obtained for Chinese fir. The analysis of climatic forcing on daily stem radial increments indicated similar correlation trends with different magnitudes for the two species, with changes in the daily stem growth positively correlated with relative humidity (RH), precipitation, and soil water content (SWC), and negatively correlated with photosynthetically active radiation (PAR), vapor pressure deficit (VPD) and temperature factors. In general, daily stem radial growth is closely associated with moisture conditions. Lagging the climatic factors showed decreasing impacts on daily stem growth. We conclude that tree growth is primarily responsive to moisture-related climatic factors, and Chinese fir shows more robust transpiration and assimilation activity. [ABSTRACT FROM AUTHOR]

Metal(loid)s pollution of groundwater in northern China is of great concern due to the increasing shortage of fresh water resources. In the present study, total 159 of groundwater samples were collected from the Miyun-Huairou-Shunyi (MHS) districts in Beijing city and the Hutuo River Plain (HRP) in Shijiazhuang city. Nineteen trace elements dissolved in groundwater were measured. Results showed that Al (12.3 %), Mn (5.3%), Zn (1.8%), As (1.8%), and Pb (1.8%) in the MHS samples, and Mn (2.2%) in the HRP samples exceeded their standard threshold of WHO and China. Exceedance of trace elements was attributed to both geochemical background and local human activities. Human health risk assessment showed that local consumers were exposed at a low level of health risk, except in specific area with a high level of arsenic. Elements of arsenic and chromium were important risk contributors in the two regions. The risk of oral exposure was greater than that of skin uptake. Children were more susceptible to non-carcinogenic risk and less to carcinogenic risk than adults. A Nemerow index and CRITIC-weighted WQI were applied to classify groundwater quality. The results from the two methods were comparable to a large extend. More population living in plain rather than mountain resulted in a gradual deterioration trend of groundwater quality from mountain to plain. The samples with poor water quality were almost collected in the area with heavy industrial and agricultural activities. The CRITIC-weighted WQI was recommended for groundwater quality assessment. A simple classification criterion was reformulated based on the MHS hazard index analysis. The groundwaters in the two research fields were not seriously polluted, but potential risks should not be ignored. [ABSTRACT FROM AUTHOR]

Aims: Multi-elemental stoichiometry can represent the biogeochemical niches of species, which can further guide community assemblage. Mycorrhizae play a key role in plant elemental acquisition. Whether and how mycorrhizal type influences the plant multi-elemental stoichiometries and elemental coordination in above- and belowground organs, however, remain unclear. Methods: We determined the concentrations of C, N, P, K, Ca, Mg, Fe, Mn, Cu, Zn, Na, Pb and Sr and some elemental ratios in the leaves and roots of arbuscular mycorrhizal (AM) trees (Phoebe bournei, Schima superba, Michelia maudiae and Cunninghamia lanceolata) and ectomycorrhizal (ECM) trees (Cyclobalanopsis glauca, Pinus massoniana and P. elliottii) in subtropical China. The effects of root traits and soil abiotic factors on elemental concentrations and ratios were reported. Results: The elemental concentrations and ratios differed substantially between the AM and ECM trees, indicating the their biogeochemical niches' differentiation. The C, P, Mg and Mn concentrations and the K:Mg andCa:Mg ratios for AM and the N, Mn and Na concentrations and the Fe:Mn ratio for the ECM species were strongly correlated between leaves and roots, but the correlations were positive or negative depending on elemental composition and mycorrhizal type. The root branching ratio, branching intensity and length played important roles in the plant elemental stoichiometries. Conclusions: The biogeochemical niche's differentiation between the AM and ECM species emphasizes the important role of mycorrhizal type in the assemblage of co-occurring species. This study offers a new opinion for species choosing in mixed forests from the view of the biogeochemical niche's separation. [ABSTRACT FROM AUTHOR]

Nitrogen (N) and phosphorus (P) fertilization are effective methods for increasing forest productivity and have been widely used in the management of forest plantations. However, how changes in the N:P ratio affect the sequestration of carbon in forests is unclear. We measured the net primary production (NPP) based on plot inventory, soil respiration (RS), autotrophic respiration (RA), and heterotrophic respiration (RH) using static chamber with GC method after trenching to compare the effects of low N fertilization (50 kg N ha−1 year−1), high N fertilization (100 kg N ha−1 year−1), P fertilization (50 kg P ha−1 year−1), low N plus P fertilization, high N plus P fertilization, and an unfertilized control on net ecosystem productivity (NEP). The NEP was significantly higher with 39–60% more under N and P fertilization than that of control. However, the mechanisms contributing to the difference varied among different treatments. Specifically, the RH was unchanged with P fertilization but significantly lower with N fertilization, while NPP was significantly higher with P or N fertilization. The NEP was higher with N plus P fertilization than with either N or P fertilization, although the interactive effect was not significant. Our findings suggested that P fertilization may be an effective method of improving timber yield and that adding both N and P fertilizers at a higher ratio may favor ecosystem carbon sequestration in P-limited stands. [ABSTRACT FROM AUTHOR]

Background and aims: Studies on the aboveground growth and traits of plants suggest that plants exhibit faster growth with greater plasticity in leaf traits to adapt to changing environments. However, our knowledge of belowground growth and trait responses and associated root foraging strategies, under competition remains limited.Methods: Using an understory species-addition experiment, we investigated the responses of function-based root (absorptive fine roots [AFRs] vs. transport fine roots [TFRs]) growth, mycorrhizal association, and order-based root traits (morphological, architectural, and chemical traits) of Pinus massoniana (native species) and Pinus elliottii (exotic species), which are the dominant coniferous tree species in subtropical China.Results: Higher understory-species diversity increased the biomass of AFRs, but not TFRs and total fine roots (AFRs plus TFRs) of both species. Higher diversity increased the biomass ratio of the AFRs and TFRs of P. elliottii, indicating a tradeoff in plant carbon investment between the two functional root modules for P. elliottii. Higher diversity increased the total root length of P. massoniana, but did not affect that of P. elliottii. Increased species diversity decreased the ectomycorrhizal colonization rate of P. massoniana, but increased that of P. elliottii. Increased species diversity altered the branching-related traits (increased branching ratio and intensity), but did not affect the morphological (diameter, specific root length, and root tissue density) or chemical traits across the root orders of either species.Conclusions: Our findings indicate that P. elliottii employed dual root foraging strategies (growth and mycorrhizal strategies) and had a cost-benefit tradeoff between AFR and TFR construction. In comparison, P. massoniana only accelerated root growth under competition. These results facilitate a better understanding of the root foraging strategies of plants and the rapid adaptation of exotic species in novel environments. [ABSTRACT FROM AUTHOR]

Background and aims: Spatially segregating root systems is a fundamental mechanism by which plants can avoid competition for resources. Understory roots contribute substantially to total forest fine-root biomass, but the strategy of function-based fine root placement between trees and understory species at the plant community level is unknown. The aim of this study was to determine the differences between trees and understory plants in the deployment of fine roots.Methods: We collected fine roots of trees and understory species in two subtropical coniferous forests, sorted the fine roots into absorptive and transport roots, determined the vertical placement of these two types of fine roots, and examined the abiotic and biotic factors that may regulate the horizontal allocation of fine roots.Results: We found that the contribution of absorptive shrub roots to absorptive roots of the woody plants was higher than the contribution of total shrub fine roots to the total fine roots of the woody plants in the topsoil. Understory plants allocated a greater proportion of their absorptive roots to transport roots (RatioA/T) and more total fine-root biomass than trees in the topsoil. Trees had a lower RatioA/T in the topsoil; but increased their contribution of fine-root biomass to the total fine-root biomass and RatioA/T with depth. The proliferation of shrub fine roots in the topsoil was affected more by soil structure (rock-fragment content and bulk density) than by nearby stems, and the growth of tree fine roots was inhibited by nearby dense and/or large stems.Conclusions: Our results provide evidence of an elaborate differentiation of root deployment between trees and understory plants. The roots of understory plants dominated the topsoil by possessing a higher branching capacity of absorptive roots than trees, filling the readily occupied macropores and being less affected by nearby stems. Trees enhance their resource foraging towards deeper soil by increasing their advantage of occupying soil volume and branching capacity of absorptive roots with depth. We also suggested that the roots of understory plants may affect ecosystemic carbon and nutrients cycling more than expected because of the disproportionately higher investment of absorptive roots in the topsoil. [ABSTRACT FROM AUTHOR]

Nitrogen (N) and phosphorus (P) additions can affect soil microbial carbon (C) accumulation. However, the mechanisms that drive the changes in residual microbial C that occur after N and P additions have not been well-defined for Chinese fir plantations in subtropical China. We set up six different treatments, viz. a control (CK), two N treatments (N1: 50 kg ha−1 a−1; N2: 100 kg ha−1 a−1), one P treatment (P: 50 kg ha−1 a−1), and two combined N and P treatments (N1P: 50 kg ha−1 a−1 of N + 50 kg ha−1 a−1 of P; N2P: 100 kg ha−1 a−1 of N + 50 kg ha−1 a−1 of P). We then investigated the influences of N and P additions on residual microbial C. The results showed that soil pH and microbial biomass decreased after N additions, while microbial biomass increased after P additions. Soil organic carbon (SOC) and residual microbial C contents increased in the N and P treatments but not in the control. Residual microbial C accumulation varied according to treatment and declined in the order: N2P > N1P > N2 > N1 > P > CK. Residual microbial C contents were positively correlated with available N, P, and SOC contents, but were negatively correlated with soil pH. The ratio of residual fungal C to residual bacterial C increased under P additions, but declined under combined N + P additions. The ratio of residual microbial C to SOC increased from 11 to 14% under the N1P and N2P treatments, respectively. Our results suggest that the concentrations of residual microbial C and the stability of SOC would increase under combined applications of N and P fertilizers in subtropical Chinese fir plantation soils. [ABSTRACT FROM AUTHOR]

Young leaves are conventionally used in the analysis to study the nutrient status of evergreen plants and their responses to environmental changes, but the role of old leaves remains poorly understood. We selected two stand types in 31-year-old Chinese fir ( Cunninghamia lanceolata) plantations with similar soil conditions but different stand densities, to test the hypothesis that nitrogen (N) concentration of old leaves and twigs is more sensitive to stand density than that of young ones. Leaves and twigs were sampled and sorted into young (one-year-old) and old (two- and three-year-old) groups. Significant differences in N concentration and carbon: nitrogen ratio between the low-density stand and high-density stand were only found in the old leaves and twigs but not in the young ones. Although the N resorption efficiency did not vary significantly with stand density, the annual N resorption rates were increased in old leaves and relatively young twigs at high stand density. These results show the potential use of old tissues in the nutrient analysis in Chinese fir plantations. Testing the generality of these results could improve the use of foliar analysis as an indicator of nutrient status and environmental changes in evergreen tree species. [ABSTRACT FROM AUTHOR]

In the optimization design of a pre-bend wind turbine blade, there is a coupling relationship between blade aerodynamic shape and structural layup. The evaluation index of a wind turbine blade not only shows on conventional ones, such as Annual energy production (AEP), cost, and quality, but also includes the size of the loads on the hub or tower. Hence, the design of pre-bend wind turbine blades is a true multi-objective engineering task. To make the integrative optimization design of the pre-bend blade, new methods for the blade's pre-bend profile design and structural analysis for the blade sections were presented, under dangerous working conditions, and considering the fundamental control characteristics of the wind turbine, an integrated aerodynamic-structural design technique for pre-bend blades was developed based on the Multi-objective particle swarm optimization algorithm (MOPSO). By using the optimization method, a three-dimensional Pareto-optimal set, which can satisfy different matching requirements from overall design of a wind turbine, was obtained. The most suitable solution was chosen from the Pareto-optimal set and compared with the original 1.5 MW blade. The results show that the optimized blade have better performance in every aspect, which verifies the feasibility of this new method for the design of pre-bend wind turbine blades. [ABSTRACT FROM AUTHOR]

Background and aims: Knowledge of the fine root dynamics of different life forms in forest ecosystems is critical to understanding how the overall belowground carbon cycling is affected by climate change. However, our current knowledge regarding how endogenous or exogenous factors regulate the root dynamics of understory vegetation is limited. The aims of this study were to test the effects of soil moisture gradient and shading on the fine root production, phenology, and turnover rate of six shrub species from a subtropical forest. Methods: We selected a suite of study sites representing different habitats with gradients of soil moisture and solar radiation (shading or no shading). We assessed the fine root production phenology, the total fine root production, and the turnover among six understory shrub species in a subtropical climate, and examined the responses of the fine root dynamics to gradients in the soil moisture and solar radiation. The shrubs included three evergreen species, Loropetalum chinense, Vaccinium bracteatum, and Adinandra millettii, and three deciduous species, Serissa serissoides, Rubus corchorifolius, and Lespedeza davidii. Results We observed that variations in the annual fine root production and turnover among species were significant in the deciduous group but not in the evergreen group. Notably, V. bracteatum and S. serissoides presented the greatest responses in terms of root phenology to gradients in the soil moisture and shading: high-moisture habitat led to a decrease and shade led to an increase in fine root production during spring. Species with smaller fine roots of the 1+2-order diameter presented more sensitive responses in terms of fine root phenology to a soil moisture gradient. Species with a lower fine root carbon- to nitrogen ratio exhibited more sensitive responses in terms of fine root annual production to shading. Soil moisture and shading did not change the annual fine root production as much as the turnover rate. Conclusions: The fine root dynamics of some understory shrubs varied significantly with soil moisture and solar radiation status and may be different from tree species. Our results emphasize the need to study the understory fine root dynamics in the achievement of a complete understanding of the overall belowground carbon cycling in a forest ecosystem, particularly ecosystems in which the understory fine root highly contributes to the belowground biomass. [ABSTRACT FROM AUTHOR]

The response and detoxification mechanisms of three freshwater phytoplankton species (the cyanobacterium Aphanizomenon flos-aquae, the green alga Pediastrum simplex, and the diatom Synedra acus) to cadmium (Cd) were investigated. The cell growth of each species was measured over 10 days, and chlorophyll a fluorescence, Cd bioaccumulation (including surface-adsorbed and intracellular Cd), and phytochelatin (PC) synthesis were determined after 96-h exposures. The growth of the three phytoplankton species was significantly inhibited when Cd concentrations were ≥5 mg L. Compared with P. simplex, greater growth inhibition in S. acus and A. flos-aquae occurred. The changes in chlorophyll fluorescence parameters including the maximal quantum yield of PSII (Fv/Fm) and relative variable fluorescence of the J point (Vj) demonstrated that the increase in Cd concentration damaged PSII in all three species. After 96-h exposures, the accumulation of surface-adsorbed Cd and intracellular Cd increased significantly in all three species, with the increase of Cd concentrations in the media; total cadmium accumulation was 245, 658, and 1670 times greater than that of the control in A. flos-aquae, P. simplex, and S. acus, respectively, after exposure to 10 mg L. Total thiols exhibited a similar trend to that of Cd accumulation. PC was found in A. flos-aquae and P. simplex in all Cd treatments. Glutathione (GSH) and PC were also produced in response to exposure to high concentrations of Cd. PC was only discovered at exposure concentrations of 10 mg L Cd and only in S. acus. The intracellular Cd/PCs ratio increased in all three phytoplankton with an increase in Cd concentrations, and a linear relationship between the ratio and the growth inhibition rates was observed with P. simplex and S. acus. Our results have demonstrated that metal detoxification mechanisms were dependent on the species. This study suggested that the variance of metal detoxification strategies, such as cadmium accumulation and PCs, might be an explanation why algal species have different sensitivity to Cd at various levels. [ABSTRACT FROM AUTHOR]

Focuses on studies conducted regarding the spread of gangrene. Factors which attribute to the cause of gangrene; How gangrene can be treated.