Hydroxyethyl Cellulose-Based Hydrogels as Controlled Release Carriers for Amorphous Solid Dispersion of Bioactive Components of Radix Paeonia Alba.

Radix Paeoniae Alba (RPA) has been used extensively in Chinese traditional medicine to treat gastrointestinal disorders, immune-modulating diseases, cancers, and numerous other conditions. A few of its active components include paeoniflorin, albiflorin, lactiflorin, and catechin. However, their therapeutic effectiveness is compromised by poor pharmacokinetic profiles, low oral bioavailability, short half-lives, and poor aqueous solubility. In this study, hydroxyethyl cellulose-grafted-2-acrylamido-2-methylpropane sulfonic acid (HEC-g-AMPS) hydrogels were successfully prepared for the controlled release of Radix Paeonia Alba-solid dispersion (RPA-SD). A total of 43 compounds were identified in RPA-SD using UHPLC-Q-TOF-MS analysis. The hydrogel network formation was confirmed by FTIR, TGA, DSC, XRD, and SEM. Hydrogels' swelling and drug release were slightly higher at pH 1.2 (43.31% swelling, 81.70% drug release) than at pH 7.4 (27.73% swelling, 72.46% drug release) after 48 h. The gel fraction, drug release time and mechanical strength of the hydrogels increased with increased polymer and monomer concentration. Furthermore, the hydrogels were porous (84.15% porosity) and biodegradable (8.9% weight loss per week). Moreover, the synthesized hydrogels exhibited excellent antimicrobial and antioxidative properties.

Response of Aboveground Net Primary Production, Species and Phylogenetic Diversity to Warming and Increased Precipitation in an Alpine Meadow.

The uncertain responses of aboveground net primary productivity (ANPP) and plant diversity to climate warming and increased precipitation will limit our ability to predict changes in vegetation productivity and plant diversity under future climate change and further constrain our ability to protect biodiversity and ecosystems. A long-term experiment was conducted to explore the responses of ANPP, plant species, phylogenetic α-diversity, and community composition to warming and increased precipitation in an alpine meadow of the Northern Tibet from 2014 to 2019. Coverage, height, and species name were obtained by conventional community investigation methods, and ANPP was obtained using observed height and coverage. Open-top chambers with two different heights were used to simulate low- and high-level climate warming. The low- and high-level increased precipitation treatments were achieved by using two kinds of surface area funnel devices. The high-level warming reduced sedge ANPP (ANPPsedge) by 62.81%, species richness (SR) by 21.05%, Shannon by 13.06%, and phylogenetic diversity (PD) by 14.48%, but increased forb ANPP (ANPPforb) by 56.65% and mean nearest taxon distance (MNTD) by 33.88%. Species richness, Shannon, and PD of the high-level warming were 19.64%, 9.67%, and 14.66% lower than those of the low-level warming, respectively. The high-level warming-induced dissimilarity magnitudes of species and phylogenetic composition were greater than those caused by low-level warming. The low- rather than high-level increased precipitation altered species and phylogenetic composition. There were significant inter-annual variations of ANPP, plant species, phylogenetic α-diversity and community composition. Therefore, climate warming and increased precipitation had non-linear effects on ANPP and plant diversity, which were due to non-linear changes in temperature, water availability, and/or soil nutrition caused by warming and increased precipitation. The inter-annual variations of ANPP and plant diversity were stronger than the effects of warming and especially increased precipitation on ANPP and plant diversity. In terms of plant diversity conservation and related policy formulation, we should pay more attention to regions with greater warming, at least for the northern Tibet grasslands. Besides paying attention to the responses of ANPP and plant diversity to climate change, the large inter-annual changes of ANPP and plant diversity should be given great attention because the large inter-annual variation indicates the low temporal stability of ANPP and plant diversity and thus produces great uncertainty for the development of animal husbandry.

Effects of Short-Term Nitrogen Addition on Soil Fungal Community Increase with Nitrogen Addition Rate in an Alpine Steppe at the Source of Brahmaputra.

The soil fungal community plays a crucial role in terrestrial decomposition and biogeochemical cycles. However, the responses of the soil fungal community to short-term nitrogen addition and its related dominant drivers still remain unclear. To address this gap, we conducted an experiment to explore how different levels of nitrogen addition (five levels: 0, 2.5, 5, 10, and 20 g N m-2 y-1) affected the soil fungal community in an alpine steppe at the source of Brahmaputra. Results showed that the reduced magnitudes of soil fungal species and phylogenetic α-diversity increased with the increasing nitrogen addition rate. Nitrogen addition significantly changed the community composition of species, and the dissimilarity of the soil fungal community increased with the increasing nitrogen addition rate, with a greater dissimilarity observed in the superficial soil (0-10 cm) compared to the subsurface soil (10-20 cm). Increases in the soil nitrogen availability were found to be the predominant factor in controlling the changes in the soil fungal community with the nitrogen addition gradient. Therefore, short-term nitrogen addition can still cause obvious changes in the soil fungal community in the alpine grassland at the source of Brahmaputra. We should not underestimate the potential influence of future nitrogen deposition on the soil fungal community in the high-altitude grassland of the Qinghai-Tibet Plateau. Adverse effects on the soil fungal community should be carefully considered when nitrogen fertilizer is used for ecosystem restoration of the alpine grassland of the Qinghai-Tibet Plateau.

Dietary sources apportionment and health risk assessment for trace elements among residents of the Tethys-Himalayan tectonic domain in Tibet, China.

Dietary intake of toxic elements (TEs) and essential trace elements (ETEs) can significantly impact human health. This study collected 302 samples, including 78 food, 104 drinking water, 73 cultivated topsoil, and 47 sedimentary rock from a typical area of Tethys-Himalaya tectonic domain. These samples were used to calculate the average daily dose of oral intake (ADDoral) and assess the health risks of five TEs and five ETEs. The results indicate that grain and meat are the primary dietary sources of TEs and ETEs for local residents. The intake of manganese (Mn) and copper (Cu) is mainly from local highland barley (66.90% and 60.32%, respectively), iron (Fe) is primarily from local grains (75.51%), and zinc (Zn) is mainly from local yak meat (60.03%). The ADDoral of arsenic (As), Mn, Fe and Zn were found to be higher than the maximum oral reference dose in all townships of study area, indicating non-carcinogenic health risks for local residents. Additionally, lead (Pb) and nickel (Ni) in 36.36% townships, and Cu in 81.82% townships were above the maximum oral reference dose, while As posed a carcinogenic risk throughout the study area. The concentrations of As, mercury (Hg), Pb, Mn, Cu Fe and selenium (Se) in grains were significantly correlated with those in soils. Moreover, the average concentrations of As in Proterozoic, Triassic, Jurassic and Cretaceous was 43.09, 12.41, 15.86 and 6.22 times higher than those in the South Tibet shell, respectively. The high concentrations of TEs and ETEs in the stratum can lead to their enrichment in soils, which, in turn, can result in excessive intake by local residents through the food chain and biogeochemical cycles . To avoid the occurrence of some diseases caused by dietary intake, it is necessary to consume a variety of exotic foods, such as high-selenium foods, foreign rice and flour in order to improve the dietary structure.

Exopolysaccharides of Serratia fonticola CPSE11 can alleviate the toxic effect of Cd2+ on Codonopsis pilosula.

In order to study the detoxification effect of microbial exopolysaccharides (EPS) on the heavy metal cadmium (Cd2+), this study took an EPS-producing Serratia fonticola CPSE11 (NZ_CP050171.1) isolated from Codonopsis pilosula root as the research object. The whole genome and EPS synthesis gene clusters of this strain were predicted and analyzed, the adsorption kinetics of EPS on Cd2+ were studied by using pseudo-first-order and second-order kinetic equations, the isothermal adsorption curves were simulated and analyzed by using the Langmuir isothermal adsorption equation, and the effects of Cd2+ and EPS on the growth of C. pilosula were explored by seed germination experiment and hydroponic experiment. The analysis revealed that this strain contained three gene clusters related to EPS synthesis, and the metabolic pathway for EPS synthesis was obtained on the basis of the whole genome analysis and microbial physiological metabolism. The molecular weight and monosaccharide composition of EPS were determined by HPLC analysis, which showed that EPS consisted of mannose, glucosamine, rhamnose, galactosamine, glucose, and galactose with a molar ratio of 1:1.74:4.57:3.96:14.04:10.28, with the molecular weight of 366,316.09 kDa. The adsorption process of EPS on Cd2+ was in accordance with the second-order kinetic model, and the results of seed germination experiments showed that EPS could promote seed germination and improve seed activity. In the hydroponic experiment, high concentration of Cd2+ (15 mg/L) caused toxic symptoms in C. pilosula, while the addition of EPS reduced the toxic effect of Cd2+ on C. pilosula, and the plant growth was significantly improved.

Ellagic Acid Inclusion Complex-Loaded Hydrogels as an Efficient Controlled Release System: Design, Fabrication and In Vitro Evaluation.

Oxidants play a crucial role in the development of oxidative stress, which is linked to disease progression. Ellagic acid is an effective antioxidant with applications in the treatment and prevention of several diseases, since it neutralizes free radicals and reduces oxidative stress. However, it has limited application due to its poor solubility and oral bioavailability. Since ellagic acid is hydrophobic, it is difficult to load it directly into hydrogels for controlled release applications. Therefore, the purpose of this study was to first prepare inclusion complexes of ellagic acid (EA) with hydroxypropyl-ß-cyclodextrin and then load them into carbopol-934-grafted-2-acrylamido-2-methyl-1-propane sulfonic acid (CP-g-AMPS) hydrogels for orally controlled drug delivery. Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), scanning electron microscopy (SEM), thermogravimetric analysis (TGA), and differential scanning calorimetry (DSC) were used to validate ellagic acid inclusion complexes and hydrogels. There was slightly higher swelling and drug release at pH 1.2 (42.20% and 92.13%) than at pH 7.4 (31.61% and 77.28%), respectively. Hydrogels had high porosity (88.90%) and biodegradation (9.2% per week in phosphate-buffered saline). Hydrogels were tested for their antioxidant properties in vitro against 2,2-diphenyl-1-picrylhydrazyl (DPPH) and 2,2'-azino-bis (3-ethylbenzothiazoline-6-sulfonic acid) (ABTS). Additionally, the antibacterial activity of hydrogels was demonstrated against Gram-positive bacterial strains (Staphylococcus aureus and Escherichia coli) and Gram-negative bacterial strains (Pseudomonas aeruginosa).

Synthesis and Evaluation of Rutin-Hydroxypropyl ß-Cyclodextrin Inclusion Complexes Embedded in Xanthan Gum-Based (HPMC-g-AMPS) Hydrogels for Oral Controlled Drug Delivery.

Oxidants play a significant role in causing oxidative stress in the body, which contributes to the development of diseases. Rutin-a powerful antioxidant-may be useful in the prevention and treatment of various diseases by scavenging oxidants and reducing oxidative stress. However, low solubility and oral bioavailability have restricted its use. Due to the hydrophobic nature of rutin, it cannot be easily loaded inside hydrogels. Therefore, first rutin inclusion complexes (RIC) with hydroxypropyl-ß-cyclodextrin (HP-ßCD) were prepared to improve its solubility, followed by incorporation into xanthan gum-based (hydroxypropyl methylcellulose-grafted-2-acrylamido -2-methyl-1-propane sulfonic acid) hydrogels for controlled drug release in order to improve the bioavailability. Rutin inclusion complexes and hydrogels were validated by FTIR, XRD, SEM, TGA, and DSC. The highest swelling ratio and drug release occurred at pH 1.2 (28% swelling ratio and 70% drug release) versus pH 7.4 (22% swelling ratio, 65% drug release) after 48 h. Hydrogels showed high porosity (94%) and biodegradation (9% in 1 week in phosphate buffer saline). Moreover, in vitro antioxidative and antibacterial studies (Staphylococcus aureus, Pseudomonas aeruginosa, and Escherichia coli) confirmed the antioxidative and antibacterial potential of the developed hydrogels.

Study of Hydroxypropyl ß-Cyclodextrin and Puerarin Inclusion Complexes Encapsulated in Sodium Alginate-Grafted 2-Acrylamido-2-Methyl-1-Propane Sulfonic Acid Hydrogels for Oral Controlled Drug Delivery.

Puerarin has been reported to have anti-inflammatory, antioxidant, immunity enhancement, neuroprotective, cardioprotective, antitumor, and antimicrobial effects. However, due to its poor pharmacokinetic profile (low oral bioavailability, rapid systemic clearance, and short half-life) and physicochemical properties (e.g., low aqueous solubility and poor stability) its therapeutic efficacy is limited. The hydrophobic nature of puerarin makes it difficult to load into hydrogels. Hence, hydroxypropyl-ß-cyclodextrin (HP-ßCD)-puerarin inclusion complexes (PIC) were first prepared to enhance solubility and stability; then, they were incorporated into sodium alginate-grafted 2-acrylamido-2-methyl-1-propane sulfonic acid (SA-g-AMPS) hydrogels for controlled drug release in order to increase bioavailability. The puerarin inclusion complexes and hydrogels were evaluated via FTIR, TGA, SEM, XRD, and DSC. Swelling ratio and drug release were both highest at pH 1.2 (36.38% swelling ratio and 86.17% drug release) versus pH 7.4 (27.50% swelling ratio and 73.25% drug release) after 48 h. The hydrogels exhibited high porosity (85%) and biodegradability (10% in 1 week in phosphate buffer saline). In addition, the in vitro antioxidative activity (DPPH (71%), ABTS (75%), and antibacterial activity (Staphylococcus aureus, Escherichia coli, and Pseudomonas aeruginosa) indicated the puerarin inclusion complex-loaded hydrogels had antioxidative and antibacterial capabilities. This study provides a basis for the successful encapsulation of hydrophobic drugs inside hydrogels for controlled drug release and other purposes.

Assessing trade-offs among productive, economic, and environmental indicators of forage systems in southern Tibetan crop-livestock integration.

Fostering crop-livestock integration via crop-forage rotation provides opportunities to cope with land degradation, feed deficit, and agropastoral sustainability. Farmers' preferences for forage options are influenced by economic benefit, environmental preference, and productive performance. However, there is little information available on evaluating multiple trade-offs of forage systems for the design of crop-forage rotations. Here, we performed a comprehensive evaluation to compare the economic, environmental, and productive indicators of five typical forage systems in terms of habitat conditions, soil ecosystem services, economic profit, and forage yield and nutritive value on the southern Tibetan Plateau. Alfalfa pasture and silage corn were mostly cultivated in lower altitudes, with more abundant precipitation, and higher growing degree days. Soil carbon and nitrogen accumulation were significantly higher in perennial alfalfa than in the other forage systems. The relative feed value of alfalfa pasture was also evidently greater than the other forage systems, whereas the yield of silage corn was among the highest. Alfalfa pasture presented superior economic benefits compared to the others. But the alfalfa pasture over six years showed a significant decrease in soil carbon and nitrogen storage, net present value, and yield. Forage systems generally have more soil carbon accumulation, but only forage legumes are more likely to positively affect soil nitrogen retention compared to cereal croplands. The trade-offs among economic, environmental, and productive indicators demonstrated that annual forage systems (silage corn, forage oat, and ryegrass) met productive target rather than environmental and economic objectives, while perennial alfalfa showed synergies among the three goals. These findings indicate that integrating crop-forage rotation, particularly introducing legume forages into farming systems is an adaptive option for crop-livestock integration on the southern Tibetan Plateau. Given the large topographic variation, suitable crop-forage systems should be designed for the heterogeneous Yarlung Zangbo River valleys. Among them, alfalfa-silage corn intercropping is recommended as a promising system to meet both productivity and profitability.

Non-growing/growing season non-uniform-warming increases precipitation use efficiency but reduces its temporal stability in an alpine meadow.

There are still uncertainties on the impacts of season-non-uniform-warming on plant precipitation use efficiency (PUE) and its temporal stability (PUEstability) in alpine areas. Here, we examined the changes of PUE and PUEstability under two scenes of non-growing/growing season non-uniform-warming (i.e., GLNG: growing-season-warming lower than non-growing-season-warming; GHNG: growing-season-warming higher than non-growing-season-warming) based on a five-year non-uniform-warming of non-growing/growing season experiment. The GLNG treatment increased PUE by 38.70% and reduced PUEstability by 50.47%, but the GHNG treatment did not change PUE and PUEstability. This finding was mainly due to the fact that the GLNG treatment had stronger influences on aboveground biomass (AGB), non-growing-season soil moisture (SMNG), temporal stability of AGB (AGBstability), temporal stability of non-growing-season air temperature (T a_NG_stability), temporal stability of growing-season vapor pressure deficit (VPDG_stability) and temporal stability of start of growing-season (SGSstability). Therefore, the warming scene with a higher non-growing-season-warming can have greater influences on PUE and PUEstability than the warming scene with a higher growing-season-warming, and there were possibly trade-offs between plant PUE and PUEstability under season-non-uniform-warming scenes in the alpine meadow.

Chitosan/xanthan gum-based (Hydroxypropyl methylcellulose-co-2-Acrylamido-2-methylpropane sulfonic acid) interpenetrating hydrogels for controlled release of amorphous solid dispersion of bioactive constituents of Pueraria lobatae.

Pueraria lobatae (Willd) Ohwi is a traditional Chinese medicine used to treat alcohol intoxication, diabetes, cerebrovascular and cardiovascular diseases. Some of its active components include the flavonoids puerarin, daidzin, daidzein, and genistin. The therapeutic efficacy of these agents is hampered by their poor pharmacokinetic profiles (rapid systemic clearance, low oral bioavailability, short half-life) and physicochemical properties (such as poor aqueous solubility and stability). In the current study, chitosan/xanthan gum-based (hydroxypropyl methylcellulose-co-2-acrylamido-2-methylpropane sulfonic acid) hydrogels for the controlled release of Pueraria lobata-solid dispersion (SD) were successfully prepared and characterized. A total of 61 compounds were identified in the Pueraria lobatae-SD using UHPLC-Q-TOF-MS analysis. Hydrogel structure was confirmed by FTIR, XRD, TGA, DSC, and SEM showed a porous structure. Correlations between hydrogels structural properties was also investigated. The hydrogels showed higher swelling after 48 h at pH 1.2 (21.15 %) than pH 7.4 (15.91 %). In vitro drug release study demonstrated that drug release was maximum at pH 1.2 (63 %) compared to pH 7.4 (49 %) after 48 h. The gel fraction of the synthesized hydrogel was increased with the increase in the polymer and crosslinker concentrations. Furthermore, in vitro studies demonstrated that the developed hydrogels possess good antioxidant and antimicrobial properties.

Synthesis of Gallic Acid-Loaded Chitosan-Grafted-2-Acrylamido-2-Methylpropane Sulfonic Acid Hydrogels for Oral Controlled Drug Delivery: In Vitro Biodegradation, Antioxidant, and Antibacterial Effects.

In this study, chitosan (CS) and 2-acrylamido-2-methylpropane sulfonic acid (AMPS)-based hydrogels were formulated by the free radical polymerization technique for the controlled release of gallic acid. Fourier transform infrared spectroscopy (FTIR) confirmed the successful preparation and loading of gallic acid within the hydrogel network. Differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA) confirmed the increased thermal stability of the hydrogels following the crosslinking and polymerization of chitosan and AMPS. In X-ray diffraction analysis (XRD), the crystallinity of the raw materials decreased, indicating strong crosslinking of the reagents and the formation of a new polymeric network of hydrogels. Scanning electron microscopy (SEM) revealed that the hydrogel had a rough, dense, and porous surface, which is consistent with the highly polymerized composition of the hydrogel. After 48 h, the hydrogels exhibited higher swelling at pH 1.2 (swelling ratio of 19.93%) than at pH 7.4 (swelling ratio of 15.65%). The drug release was analyzed using ultraviolet-visible (UV-Vis) spectrophotometer and demonstrated that after 48 h, gallic acid release was maximum at pH 1.2 (85.27%) compared to pH 7.4 (75.19%). The percent porosity (78.36%) and drug loading increased with the increasing concentration of chitosan and AMPS, while a decrease was observed with the increasing concentration of ethylene glycol dimethyl methacrylate (EGDMA). Crosslinking of the hydrogels increased with concentrations of chitosan and EGDMA but decreased with AMPS. In vitro studies demonstrated that the developed hydrogels were biodegradable (8.6% degradation/week) and had antimicrobial (zone of inhibition of 21 and 16 mm against Gram-positive bacteria Escherichia coli and Staphylococcus aureus as well as 13 mm against Gram-negative bacteria Pseudomonas aeruginosa, respectively) and antioxidant (73% DPPH and 70% ABTS) properties. Therefore, the prepared hydrogels could be used as an effective controlled drug delivery system.

Gallic Acid-Loaded Sodium Alginate-Based (Polyvinyl Alcohol-Co-Acrylic Acid) Hydrogel Membranes for Cutaneous Wound Healing: Synthesis and Characterization.

Traditional wound dressings often cannot treat wounds caused by bacterial infections or other wound types that are insensitive to these wound treatments. Therefore, a biodegradable, bioactive hydrogel wound dressing could be an effective alternative option. The purpose of this study was to develop a hydrogel membrane comprised of sodium alginate, polyvinyl alcohol, acrylic acid, and gallic acid for treating skin wounds. The newly developed membranes were analyzed using Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), differential scanning calorimetry (DSC) and scanning electron microscopy (SEM), X-ray diffraction analysis (XRD), sol-gel fraction, porosity, mechanical strength, swelling, drug release and data modelling, polymeric network parameters, biodegradation, and antioxidation (DPPH and ABTS) and antimicrobial activity against Gram-positive and negative bacteria. The results revealed that hydrogel membranes were crosslinked successfully and had excellent thermal stability, high drug loading, greater mechanical strength, and exhibited excellent biodegradation. Additionally, the swelling ability and the porosity of the surface facilitated a controlled release of the encapsulated drug (gallic acid), with 70.34% release observed at pH 1.2, 70.10% at pH 5.5 (normal skin pH), and 86.24% at pH 7.4 (wounds pH) in 48 h. The gallic acid-loaded hydrogel membranes showed a greater area of inhibition against Pseudomonas aeruginosa, Staphylococcus aureus, and Escherichia coli bacteria as well as demonstrated excellent antioxidant properties. Based on Franz cell analyses, the permeation flux of the drug from optimized formulations through mice skin was 92 (pH 5.5) and 110 (pH 7.4) µg/cm2·h-1. Moreover, hydrogel membranes retained significant amounts of drug in the skin for 24 h, such as 2371 (pH 5.5) and 3300 µg/cm2 (pH 7.4). Acute dermal irritation tests in rats showed that hydrogel membranes were nonirritating. Hydrogel membranes containing gallic acid could be an effective option for improving wound healing and could result in faster wound healing.

Isolation of Phenolic Compounds from Raspberry Based on Molecular Imprinting Techniques and Investigation of Their Anti-Alzheimer's Disease Properties.

Alzheimer's disease is the most common neurodegenerative disease, characterized by memory loss and cognitive dysfunction. Raspberry fruits contain polyphenols which have antioxidant and anti-inflammatory properties. In this study, we used molecular imprinting technology to efficiently isolate phenolic components from the raspberry ethyl acetate extracts. Six phenolic components (ellagic acid, tiliroside, kaempferol-3-o-rutoside, gallic acid, ferulic acid and vanillic acid) were identified by UPLC-Q-TOF-MS analysis. Molecular docking was used to predict the anti-inflammatory effects and anti-Alzheimer's potential of these isolated compounds, which showed a good binding ability to diseases and related proteins. However, the binding energy and docking fraction of ellagic acid, tiliroside, and kaempferol-3-o-rutoside were better than those of gallic acid, ferulic acid and vanillic acid. Additionally, by studying the effects of these six phenolic components on the LPS-induced secretion of inflammatory mediators in murine microglial (BV2) cells, it was further demonstrated that they were all capable of inhibiting the secretion of NO, IL-6, TNF-α, and IL-1ß to a certain extent. However, ellagic acid, tiliroside, and kaempferol-3-o-rutoside have better inhibitory effects compared to others. The results obtained suggest that the phenolic components extracted from ethyl acetate extracts of raspberry by molecularly imprinted polymers have the potential to inhibit the progression of Alzheimer's disease.

Hydrochemical characteristics of surface waters and their relationships to the Kashin-Beck Disease in Longzi County, Tibet.

Although previous studies have been reported between the Kashin-Beck Disease (KBD) epidemic and the hydrochemical characteristics of surface waters, the etiology of the disease remains unclear. In the present study, we comprehensively investigated the relationship between the KBD and the hydrochemical characteristics of surface waters in Longzi County. Results show that, the pH (mean = 7.27 ± 0.30), total hardness (TH, mean = 57.08 ± 45.74 mg L-1), total dissolved solids (TDS, mean = 67.56 ± 44.00 mg L-1) and oxidation-reduction potential (ORP, mean = 84.11 ± 23.55 mV) of surface waters in KBD endemic areas are lower than those in the non-KBD endemic areas (means of pH = 7.49 ± 0.30; TH = 262.06 ± 123.29 mg L-1; TDS = 253.25 ± 100.39 mg L-1; ORP = 215.90 ± 55.99 mV). These results suggest that long-term consumption of low TDS, essential trace elements (e.g., nickel, cobalt, iron, selenium, zinc, molybdenum, and iodine) deficient, and potential toxic elements (e.g., arsenic) enriched waters by humans likely causes the KBD. Environmental factors such as the geology and geomorphology may produce biogeochemical imbalance, geomorphic, vegetation types and local climatic conditions may have significant impact on food fungi toxin poisoning and water organic compound poisoning, and these also impact the KBD occurrence.

Geochemical characteristics and source apportionment of toxic elements in the Tethys-Himalaya tectonic domain, Tibet, China.

Toxic elements (TEs) in soil threaten the eco-environmental system and human health. The identification and prediction of sources and high-risk areas of TEs in soil are fundamental for regional pollution prevention and control. In this study, geostatistical methods and GIS-based approaches were used to quantitatively analyze the spatial distribution, geochemical characteristics, key driving factors, and their interactive effects of TEs in soil from a typical area of the Tethys-Himalaya tectonic domain in Tibet based on an integrated approach combining positive matrix factorization and GeoDetector models. The mean contents of chromium, arsenic (As), cadmium, mercury and lead in the soil exceeded the Tibetan background values, with 66.20% of As being higher than the screening values. The spatial distribution of TEs content in the soil was primarily affected by geogenic source factors (primarily geology types, soil parent materials, soil types, and soil pH), and environmental source factors (primarily precipitation and vegetation types) and anthropogenic source factors (primarily income of residents and land-use types) also had the same contribution approximately. Compared with that for individual driving factors, the interaction between most pairs of driving factors enhanced their explanatory power. The high-risk areas for soil As pollution were primarily distributed in the valley areas of the upper reaches of the Longzi River Basin. Therefore, to guarantee the health of residents and the security and sustainability of agricultural production in the study area, regular monitoring and soil remediation should be used to reduce the migration and transformation of As in the local biogeochemical cycle. This study provides new ideas for the regional prediction of high-risk areas for soil pollution, which has guiding importance and reference value for the control and management of large-scale soil pollution.

Effect of citric acid residue and short-chain fatty acids on fermentation quality and aerobic stability of lucerne ensiled with lactic acid bacteria inoculants.

The experiment aimed to compare the effects of citric acid residue (CAR) to that of three commonly used short-chain fatty acids on the fermentation quality, aerobic stability and structural carbohydrate degradation of lucerne ensiled with lactic acid bacteria (LAB) inoculants. Fresh lucerne was ensiled with distilled water (control), LAB inoculant (L), CAR + LAB inoculant (CL), formic acid + LAB inoculant (FL), acetic acid + LAB inoculant (AL) and propanoic acid + LAB inoculant (PL) for 50 days. Chemical composition and microbial populations were determined after ensiling. The residual silages ensiled for 50 days were evaluated for aerobic stability. Compared with control, CL, FL, AL and PL treatments significantly (p < 0.05) decreased pH, ammonia nitrogen (NH3 -N) and butyric acid contents and increased lactic acid, acetic acid and propionic acid contents. Among them, CL silages had the lowest pH, dry matter and water-soluble carbohydrate (WSC) content, whereas the population of LAB and the lactic acid contents were highest. Besides, CL outperformed in enhancing fibre degradation, CL silages significantly decreased (p < 0.05) neutral detergent fibre, acid detergent fibre, hemicellulose and cellulose contents compared with control and had the highest Flieg's point. All treated-silages improved the aerobic stability compared with control, of which L improved 32 h, whereas CL, FL, AL and PL improved 46, 20, 46, >64 h, respectively. Applying a combination of CAR and LAB inoculant improved the fermentation quality and structural carbohydrate degradation of lucerne silage and had a similar effect on aerobic stability compared with other three short-chain fatty acids. The CAR had a comparable effect on enhancing the fermentation quality compared with three short-chain fatty acids. Thus, the combination of CAR and LAB inoculant might be used as an ideal additive for lucerne silage making with low WSC and high moisture content.

Comparative analysis of carbon and nitrogen metabolism, antioxidant indexes, polysaccharides and lobetyolin changes of different tissues from Codonopsis pilosula co-inoculated with Trichoderma.

Codonopsis pilosula is a traditional Chinese herbal medicinal plant and contains various bioactive components, such as C. pilosula polysaccharides (CPPs) and lobetyolin (Lob). Hydrogen peroxide (H2O2) and nitric oxide (NO) are gaseous molecule and have been well known for their ability to relieve some adverse influences on plant from abiotic stress. Endophytic fungus is non-pathogenic plant-associated fungus that could play a significant role in improving plant tolerance by signal molecule. In this work, we determined how inoculation of Trichoderma strain RHTA01 with C. pilosula changed the plant's growth, metabolite accumulation, and related enzyme activity. Results demonstrated that application of Trichoderma strain RHTA01 significantly improved the growth of C. pilosula. Moreover, it noticeably decreased antioxidant enzyme superoxide dismutase (SOD) and catalase (CAT) activity in C. pilosula leaves, reduced the content of H2O2 and malondialdehyde (MDA), and weakened the peroxidation of cell membrane lipids, which reduced the damage of abiotic stress to C. pilosula. Research has shown that it had obvious effects on levels of nitrogen and carbon metabolic enzymes. For example, sucrose synthase (SS) and acid invertase (AI) levels in C. pilosula roots were nearly 1.43 and 1.7 times higher, respectively, than those in the control (CK) group. In addition, it was notable that the production of CPPs and Lob, the most significant secondary metabolites in C. pilosula, were influenced by Trichoderma strain RHTA01. The obtained results indicate that inoculating C. pilosula with Trichoderma stimulates the carbon and nitrogen metabolism of the plant, and helps to increase the content of CPPs and Lob in the root of the plant.

Warming homogenizes apparent temperature sensitivity of ecosystem respiration.

Warming-induced carbon loss through terrestrial ecosystem respiration (Re) is likely getting stronger in high latitudes and cold regions because of the more rapid warming and higher temperature sensitivity of Re (Q 10). However, it is not known whether the spatial relationship between Q 10 and temperature also holds temporally under a future warmer climate. Here, we analyzed apparent Q 10 values derived from multiyear observations at 74 FLUXNET sites spanning diverse climates and biomes. We found warming-induced decline in Q 10 is stronger at colder regions than other locations, which is consistent with a meta-analysis of 54 field warming experiments across the globe. We predict future warming will shrink the global variability of Q 10 values to an average of 1.44 across the globe under a high emission trajectory (RCP 8.5) by the end of the century. Therefore, warming-induced carbon loss may be less than previously assumed because of Q 10 homogenization in a warming world.

The Change in Environmental Variables Linked to Climate Change Has a Stronger Effect on Aboveground Net Primary Productivity Than Does Phenological Change in Alpine Grasslands.

More and more studies have focused on responses of ecosystem carbon cycling to climate change and phenological change, and aboveground net primary productivity (ANPP) is a primary component of global carbon cycling. However, it remains unclear whether the climate change or the phenological change has stronger effects on ANPP. In this study, we compared the effects of phenological change and climate change on ANPP during 2000-2013 across 36 alpine grassland sites on the Tibetan Plateau. Our results indicated that ANPP showed a positive relationship with plant phenology such as prolonged length of growing season and advanced start of growing season, and environmental variables such as growing season precipitation (GSP), actual vapor pressure (Ea), relative humidity (RH), and the ratio of GSP to ≥5°C accumulated temperature (GSP/AccT), respectively. The linear change trend of ANPP increased with that of GSP, Ea, RH, and GSP/AccT rather than phenology variables. Interestingly, GSP had the closer correlation with ANPP and meanwhile the linear slope of GSP had the closer correlation with that of ANPP among all the concerned variables. Therefore, climate change, mainly attributed to precipitation change, had a stronger effect on ANPP than did phenological change in alpine grasslands on the Tibetan Plateau.