Comprehensive chlorine heterogeneous chemistry is incorporated
into the Community Multiscale Air Quality (CMAQ) model to evaluate the impact
of chlorine-related heterogeneous reaction on diurnal and ...nocturnal nitrate
formation and quantify the nitrate formation from gas-to-particle
partitioning of HNO3 and from different heterogeneous pathways. The
results show that these heterogeneous reactions increase the atmospheric
Cl2 and ClNO2 level (∼ 100 %), which further
affects the nitrate formation. Sensitivity analyses of uptake coefficients
show that the empirical uptake coefficient for the O3 heterogeneous
reaction with chlorinated particles may lead to the large uncertainties in
the predicted Cl2 and nitrate concentrations. The N2O5
uptake coefficient with particulate Cl− concentration dependence
performs better in capturing the concentration of ClNO2 and nocturnal
nitrate concentration. The reaction of OH and NO2 in the daytime
increases the nitrate by ∼15 % when the heterogeneous chlorine
chemistry is incorporated, resulting in more nitrate formation from
HNO3 gas-to-particle partitioning. By contrast, the contribution of
the heterogeneous reaction of N2O5 to nitrate concentrations
decreases by about 27 % in the nighttime, when its reactions with
chlorinated particles are considered. However, the generated gas-phase
ClNO2 from the heterogeneous reaction of N2O5 and
chlorine-containing particles further reacts with the particle surface to
increase the nitrate by 6 %. In general, this study highlights the
potential of significant underestimation of daytime concentrations and overestimation of
nighttime nitrate concentrations for chemical transport models without proper
chlorine chemistry in the gas and particle phases.
Endophytes play a significant role in regulating plant root development and facilitating nutrient solubilization and transportation. This association could improve plant growth. The present study has ...uncovered a distinct phenotype, which we refer to as "white root", arising from the intricate interactions between endophytic fungi and bacteria with the roots in a sugarcane and bamboo fungus (
) intercropping system.
We investigated the mechanisms underlying the formation of this "white root" phenotype and its impact on sugarcane yield and metabolism by metabarcoding and metabolome analysis.
Initial analysis revealed that intercropping with
increased sugarcane yield by enhancing the number of viable tillers compared with bagasse and no input control. Metabarcoding based on second-generation and third-generation sequencing indicated that
and
dominates the fungal and bacterial composition in the "white root" phenotype of sugarcane root. The coexistence of
and
as endophytes induced plant growth-promoting metabolites in the sugarcane root system, such as lysoPC 18:1 and dihydrobenzofuran, probably contributing to increased sugarcane yield. Furthermore, the association also enhanced the metabolism of compounds, such as naringenin-7-O-glucoside (Prunin), naringenin-7-O-neohesperidoside (Naringin)*, hesperetin-7-O-neohesperidoside (Neohesperidin), epicatechin, and aromadendrin (Dihydrokaempferol), involved in flavonoid metabolism during the formation of the endophytic phenotype in the sugarcane root system. These observations suggest that the "white root" phenotype promotes sugarcane growth by activating flavonoid metabolism. This study reports an interesting phenomenon where
, coordinate with the specific bacteria invade, forms a "white root" phenotype with sugarcane root. The study also provides new insights into using
as a soil inoculant for promoting sugarcane growth and proposes a new approach for improve sugarcane cultivation.
•Responses of melon seedlings to suboptimal low temperature are diverse.•Suboptimal low temperature inhibits melon growth and delays flowering in morphology.•Suboptimal low temperature reduces melon ...chlorophyll, promotes soluble sugar and proline in physiology.•Free proline and soluble sugar might be the key compounds to melon cold acclimation.
Crop adaptation to environmental changes showed a short-term effect characterized by physiological and biochemical changes, and a long-term effect characterized by changes in dry matter accumulation. The effects of suboptimal low temperature (15 °C/10 °C, day/night, 5 days) on physiological characters, growth and development were investigated in 16 genotypes of melon seedlings. For short-term effect, suboptimal low temperature mainly induced free proline (up to 179.5%) and soluble sugar accumulated (up to 181.4%), impaired plasma membrane, and inhibited chlorophyll biosynthesis and PSII activity. For long-term effect, it mainly inhibited plant height and the first female flower opening (FFFO), but promoted stem diameter growth. Comprehensive analysis showed that nine indicators were suitable for assessing suboptimal low temperature effect on melon seedlings, including chlorophyll content (total, chl.a and chl.b), plant height, internode length, stem diameter, free proline, soluble sugar, and FFFO. Furthermore, sixteen genotypes were divided into four groups based on the nine parameters. Cluster I was characterized by high chlorophyll content and plant height (two genotypes); Cluster II was mainly characterized by intermediate value in 7 - 8 indexes (five genotypes); Cluster III was characterized by most indexes were about one third of the maximum value (seven genotypes); Cluster IV was characterized by lower value in all indexes (two genotypes). Our research can provide detailed data to clarify the response characteristics of different melon populations to suboptimal low temperature, and provide reference for cold acclimation of melon and other cucurbits in practice.
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Nitrate became the most significant component of secondary inorganic aerosols (SNA, the sum of sulfate, nitrate and ammonium ions) as the emissions of sulfur dioxide (SO2) have been greatly reduced ...in China in recent years. In the Yangtze River Delta (YRD), nitrate could contribute 56% of SNA and 34% of total PM2.5 during haze episodes. In this study, a modified Community Multiscale Air Quality (CMAQ) model was used to provide a comprehensive understanding of nitrate source and formation under severe pollution during winter 2015 and 2016. Three haze episodes (HEP1, HEP2 and HEP3) and one clean episode (CEP) were selected to investigate the emission sector and regional contributions to nitrate at six environmental monitoring sites in the YRD. Source apportionment results showed that industry (35%), transportation (32%) and power (28%) sectors were the important sources of nitrate during haze episodes. Regional transport (60–98%) was responsible for the high nitrate concentrations in the YRD. During haze episodes, the high ozone production (PO3) rate (up to 700 ppb/h) and hydroxyl radicals (OH) removal rate (up to 9 ppb/h) were observed in the daytime indicating the important atmospheric oxidation capacity in the YRD. Also, the nitrogen oxidation ratio (NOR) analysis elucidated that daytime photochemistry played an important role in nitrate formation and the heterogeneous chemistry enhanced the high nitrate at night. Results from emission scenario analysis demonstrated that averaged nitrate concentration in Shanghai decreased by 18% during haze episodes under emission reductions of 20% NOx, NH3 and VOC in the YRD, and Shandong, Shanxi, Henan and Hebei provinces. Emission reduction on the regional scale (one city and its surrounding areas) is an efficient strategy to reduce nitrate concentration in the YRD.
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•Regional transport is the main origin of nitrate during haze episodes in the YRD.•Photochemistry is important in nitrate formation during the daytime in the YRD.•Emission reduction on a regional scale (one city and its surrounding areas) is effective to control nitrate.
To understand the lake status and reasons of eutrophication at Lake Erhai in recent years, water quality, including water temperature (T), pH, dissolved oxygen (DO), total nitrogen (TN), total ...phosphorus (TP) and chlorophyll-a (Chl-a) from 2016 to 2020 was monitored and analyzed. The results showed no obvious thermocline in the vertical direction at Lake Erhai, while Chl-a demonstrated obvious spatiotemporal distribution characteristics in Lake Erhai. Chl-a concentrations increased to a maximum in summer in August with the low TN:TP value, leading to algal blooms, most notably in the southern lakes. Low pH and DO appeared due to the thermocline of Erhai Lake (August 2016). A large area of algae distribution due to the increase of total phosphorus appeared in the northern lake area of Lake Erhai in December 2016, with a tendency of mesotrophic to light eutrophic in summer by the nutritional evaluation of Lake Erhai, especially in the central lake area and the northern lake area. Pearson’s correlation coefficient and principal component analysis showed a significant positive correlation between Chl-a and T (r = 0.34, p ≤ 0.01) and TP (r = 0.31 p ≤ 0.01) in the mesotrophic Lake Erhai, indicating that TP content was one of the triggering factors for the algal blooming. Based on the spatiotemporal changes in water quality parameters and their relationship with eutrophication, scientific agencies should implement management strategies to protect Lake Erhai, supplemental to the costly engineering measurements.
Poly(vinyl pyrrolidone) (PVP)-based carbon/Fe3C composite nanofibers (C/Fe3C CNFs) have been successfully prepared by carbonization of as-electrospun PVP/ferric nitrate nanofibers. Unlike the ...pristine PVP nanofibers, the PVP/ferric nitrate nanofibers can retain fibers structure after carbonization, in which Fe3C nanoparticles are well-dispersed. More importantly, the as-prepared wax composites exhibit high electromagnetic wave absorption abilities, which can be attributed to the formation of the C/Fe3C CNFs “conductive network”, and leads to a more effective dielectric loss in terms of dissipating the induced current in the wax composites. Specifically, the CNFs/wax composites with a low filler ratio of 10wt% shows the minimum reflection loss of −62.6dB at 11.25GHz in a thin matching thickness of 3.6mm, and the effective bandwidth below −10dB can reach up to 6.5GHz. Thus, this work demonstrates a facile, cost-effective synthesized strategy to prepare carbon-based lightweight composite nanofibers with superior electromagnetic wave absorption properties.
Longitudinal cracks are the typical surface defects of continuous casting slabs, resulting in additional processing or even casting interruption. Monitoring longitudinal crack defects is of great ...significance in stabilizing and improving the slab quality. Herein, a monitoring model is developed to recognize the longitudinal crack defect of continuous casting slabs using principal component analysis (PCA) and support vector machine (SVM). First, the typical characteristics of the temperature patterns corresponding to the longitudinal crack defect are extracted, including the normal casting temperature with small and large fluctuations, as well as the longitudinal crack temperature. Then, PCA is used to reduce the dimension of these characteristics for removing the redundancy and reducing the computational burden. Subsequently, an SVM is applied to identify normal and longitudinal crack temperature patterns for training the monitoring model PCA–SVM. The monitoring performance is verified by the test data, in which the training accuracy and test accuracy are 100% and 96%, respectively. It is worth mentioning that the model can successfully predict all the real longitudinal crack defects, showing excellent detection performance. The established model is expected to provide a theoretical basis and a reliable way for online monitoring of slab surface cracks.
Herein, the typical characteristics that can fully characterize the 1D propagation feature of longitudinal crack temperature are captured. Principal component analysis and support vector machine are integrated to construct a model to predict longitudinal cracks. The detection idea is ingeniously conceived, and the prediction performance reflects the feasibility and application potential of machine learning in slab defect detection.
Toxic trace elements represent an ongoing environmental problem in aquatic ecosystems. However, a lack of quantitative analysis and accurate evaluation has led to unguided control and water ...management strategies. Lake Yangzong is the main freshwater resource for nearly one million people in Yunnan Province in southwestern China. It has been heavily contaminated in recent years by significant anthropogenic activities including an industrial phosphor-gypsum spill, sewage effluent, and chemical remediation processes. Herein, we combine eco-environmental indices with multiple statistical analyses to determine the ecological risk and degree of contamination of 11 toxic trace elements in the upper sediments of the lakebed. Local geochemical background concentrations were determined using robust regression models developed from sediment core data. Pollution indices (EF/PLI) indicate that severe As contamination was centralized in the southwestern part of the lake. Other toxic trace elements (e.g., Cd, Cu, Pb) are slightly to moderately enriched, and progressively decrease from the northwestern to the southeastern areas of the lake. A more accurate and sensitive index (PCR) was proposed herein, suggesting that contamination was dominated by As and Pb in different lake sections. The northern section of the lake and the southwestern bay exhibited higher contaminant levels than other regions of the lake. Bio-toxic indices (ERF/PERI) indicate that As and Cd pose a high ecological risk, whereas Cu and Pb pose a low risk to biota. Statistical analyses (PCA/PMF) demonstrate that metal contaminants originated from three types of anthropogenic sources: the smelting of metal ores, the leakage of tailings effluent, and coal consumption.
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•Arsenic is the dominant contaminant in surface sediment and poses a potentially high risk.•The southwest and northwest coasts are more contaminated by risk elements than other lake areas.•The main anthropogenic sources of toxic trace metals in LYZ are ore smelting, tailings leakage, and coal consumption.•Local background can improve sensitivity and reliability of assessment results.•Compared to other data processing tools, PCR is an efficient tool for spatial and attribution analyses.
Aims/hypothesis
The association between dietary Mn and type 2 diabetes is unclear. We aimed to elucidate whether dietary Mn is associated with type 2 diabetes, to investigate whether this association ...is independent of dietary total antioxidant capacity (TAC) and to explore the underlying mechanisms in their association.
Methods
Two prospective cohorts of 3350 and 7133 Chinese adults (20–74 years old) were enrolled including, respectively, 244 and 578 individuals newly diagnosed with type 2 diabetes, with mean values of 4.2 and 5.3 years of follow-up. Cox’s proportional-hazards regression and linear regression were performed to investigate the association between dietary Mn and type 2 diabetes (diagnosed by OGTT) or HbA
lc
and to analyse the joint association between dietary Mn and TAC. Restricted cubic spline (RCS) regression was applied to the non-linear association between dietary Mn and incidence of type 2 diabetes. Mediation analysis was applied to explore potential mediators in their association in a subgroup of 500 participants.
Results
Dietary Mn intakes were 4.58 ± 1.04 and 4.61 ± 1.08 (mean ± SD) mg/day in the two cohorts. Dietary Mn was inversely associated with type 2 diabetes incidence and HbA
lc
concentration in both cohorts (
p
trend
< 0.01 and <0.01 for type 2 diabetes, and
p
trend
< 0.01 and =0.02 for HbA
lc
, respectively, in each cohort) independent of TAC, adjusted for age, sex, BMI, tobacco use, alcohol consumption, physical activity, diabetes inheritance, total energy, carbohydrate, total fatty acids, fibre, calcium, Mg, hypertension, hyperlipidaemia, and impaired glucose tolerance or FBG (all at baseline). Their inverse association was stronger in the presence of diets with high, compared with low, TAC. In RCS, intakes of >6.01 and 6.10–6.97 mg/day were associated with a significantly lower type 2 diabetes incidence in the two respective cohorts. Mediation analysis showed that high plasma Mn and low oxidative stress (increased Mn superoxide dismutase and decreased 8-hydroxydeoxyguanosine) contributed to the association between dietary Mn and both type 2 diabetes and HbA
lc
.
Conclusions/interpretation
Dietary Mn was inversely associated with type 2 diabetes independently of TAC. In addition, this association was stronger in a high- rather than low-TAC diet. Plasma Mn and oxidative stress were mediators in the association between dietary Mn and type 2 diabetes. Future studies on absolute Mn intake should be conducted to study the potential non-linearity and optimal levels of dietary Mn and type 2 diabetes.
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