A meta-analysis on crop growth and heavy metals accumulation with PGPB inoculation in contaminated soils

Plant growth-promoting bacteria (PGPB) offer a promising solution for mitigating heavy metals (HMs) stress in crops, yet the mechanisms underlying the way they operate in the soil-plant system are not fully understood. We therefore conducted a meta-analysis with 2037 observations to quantitatively evaluate the effects and determinants of PGPB inoculation on crop growth and HMs accumulation in contaminated soils. We found that inoculation increased shoot and root biomass of all five crops (rice, maize, wheat, soybean, and sorghum) and decreased metal accumulation in rice and wheat shoots together with wheat roots. Key factors driving inoculation efficiency included soil organic matter (SOM) and the addition of exogenous fertilizers (N, P, and K). The phylum Proteobacteria was identified as the keystone taxa in effectively alleviating HMs stress in crops. More antioxidant enzyme activity, photosynthetic pigment, and nutrient absorption were induced by it. Overall, using PGPB inoculation improved the growth performance of all five crops, significantly increasing crop biomass in shoots, roots, and grains by 33 %, 35 %, and 20 %, respectively, while concurrently significantly decreasing heavy metal accumulation by 16 %, 9 %, and 37 %, respectively. These results are vital to grasping the benefits of PGPB and its future application in enhancing crop resistance to HMs.

Sulfur enhances iron plaque formation and stress resistance to reduce the transfer of Cd and As in the soil-rice system

Sulfur plays an essential role in agricultural production, but few studies have been reported on how sulfur simultaneously impacts the transformation of cadmium (Cd) and arsenic (As) in the soil-rice system. This research selected two soils co-contaminated with both Cd and As, varying in acidity and alkalinity levels, to study the impacts of elemental sulfur (S) and calcium sulfate (CaSO4) on the migration and accumulation of Cd and As by rice. Results indicated that two types of sulfur had a substantial (P < 0.05) impact on decreasing the contents of Cd (28.3-50.4 %) and As (20.1-38.6 %) in brown rice in acidic and alkaline soils. They also increased rice biomass (29.3-112.8 %) and reduced Cd transport coefficient (27.2-45.6 %) significantly (P < 0.05). Notably, sulfur augmented the generation of iron plaque on rice root surfaces, which increased the fixation of Cd (17.6-61.0 %) and As (14.0-45.9 %). SEM-EDS results also indicated that the rice root surface exhibited significant enrichment of Fe, Cd, and As. The mechanism of simultaneous Cd and As immobilization by sulfur application was mainly ascribed to the contribution of iron plaque. Additionally, sulfur reduced the contents of Cd and As in soil porewater and promoted the transformation of As(III) to As(V) to reduce the toxicity of As. The K-edge XAFS of As in iron plaque also confirmed that sulfur application significantly promoted As(III) oxidation. Sulfur also promoted the activities of antioxidant enzymes and the contents of NPT, GSH, and PCs in rice plants. In general, this study establishes a foundation for sulfur to lower As and Cd bioavailability in paddy soils, enhance iron plaque and rice resistance, and reduce heavy metal accumulation.

Meta-analysis of impacts of microplastics on plant heavy metal(loid) accumulation

The co-occurrence of microplastics (MPs) and heavy metal(loid)s (HMs) has attracted growing scientific interest because of their wide distribution and environmental toxicity. Nevertheless, the interactions between MPs and HMs in soil-plant systems remain unclear. We conducted a meta-analysis with 3226 observations from 87 independent studies to quantify the impact of MPs addition on the plant biomass and HMS accumulation. Co-occurrence of MPs and HMs (except for As) induced synergistic toxicity to plant growth. MPs promoted their uptake in the shoot by 11.0% for Cd, 30.0% for Pb, and 47.1% for Cu, respectively. In contrast, MPs caused a significant decrease (22.6%, 17.9-26.9%) in the shoot As accumulation. The type and dose of MPs were correlated with the accumulation of HMs. MPs increased available concentrations of Cd, Pb, and Cu, but decreased available As concentration in soils. Meanwhile, MPs addition significantly lowered soil pH. These findings may provide explanations for MPs-mediated effects on influencing the accumulation of HMs in plants. Using a machine learning approach, we revealed that soil pH and total HMs concentration are the major contributors affecting their accumulation in shoot. Overall, our study indicated that MPs may increase the environmental risks of HMs in agroecosystems, especially metal cations.

Sources and human health risks associated with potentially toxic elements (PTEs) in urban dust: A global perspective

Long-term exposure to urban dust containing potentially toxic elements (PTEs) poses detrimental impacts on human health. However, studies estimating human health risks in urban dusts from a global perspective are scarce. We evaluated data for twelve PTEs in urban dusts across 59 countries from 463 published articles, including their concentrations, input sources, and probabilistic risks to human health. We found that 34.1 and 60.3% of those investigated urban dusts have been heavily contaminated with As and Cd, respectively. The input of PTEs was significantly correlated with economic structure due to emissions of industrial activities and traffic emissions being the major sources. Based on the Monte Carlo simulation, we found that the mean hazard index below the safe threshold (1.0) could still cause non-negligible risks to human health. Arsenic and Cr were the major PTEs threatening human health, and relatively high risk levels were observed in cities in China, Korea, Chile, Malaysia, and Australia. Importantly, our analysis suggested that PTEs threaten the health of approximately 92 million adults and 280 million children worldwide. Overall, our study provides important foundational understanding and guidance for policy decision-making to reduce the potential risks associated with PTE exposure and to promote sustainable development of urban economies.

Examining diverse remediation mechanisms of biochar in soil contaminated with polycyclic aromatic hydrocarbon (PAH) of various ring structures: A global meta-analysis

Biochar is a widely recognized solution for addressing polycyclic aromatic hydrocarbon (PAH) contamination. However, it is unclear how the different physicochemical properties of PAHs affect remediation mechanisms, thereby affecting the remediation efficiency of biochar. In this study, a meta-analysis of 56 studies with 2236 observations was conducted to quantify the contributions of the preparation parameters and physicochemical properties of biochar, soil properties, and application measures to remediation efficiency. The research results revealed that PAH contents in the contaminated soil were significantly reduced by an average of 24.99 % after the application of biochar. Random Forest analysis identified feedstock, biochar SSA, soil pH, and rate of biochar application to be the most critical factors among the four categories. The reduction of PAH contents in the contaminated soil first decreased from 37.61 % to 17.44 % and then increased to 40.29 % with an increase in the number of aromatic rings from 2 to 6. Our study results suggest that biochar prepared from bio-waste at low temperatures could be favorable for reducing the content of NAP in soil. Wood-derived biochar pyrolyzed at a relatively high temperature is recommended for remediation of soil contaminated with PAHs with 5 or 6 aromatic rings. Our study provides a new perspective and an optimized strategy for the remediation of PAH-contaminated soils with biochar.

Interaction of microplastics with heavy metals in soil: Mechanisms, influencing factors and biological effects

Microplastics (MPs) and heavy metals (HMs) in soil contamination are considered an emerging global problem that poses environmental and health risks. However, their interaction and potential biological effects remain unclear. Here, we reviewed the interaction of MPs with HMs in soil, including its mechanisms, influencing factors and biological effects. Specifically, the interactions between HMs and MPs mainly involve sorption and desorption. The type, aging, concentration, size of MPs, and the physicochemical properties of HMs and soil have significant impacts on the interaction. In particular, MP aging affects specific surface areas and functional groups. Due to the small size and resistance to decomposition characteristics of MPs, they are easily transported through the food chain and exhibit combined biological effects with HMs on soil organisms, thus accumulating in the human body. To comprehensively understand the effect of MPs and HMs in soil, we propose combining traditional experiments with emerging technologies and encouraging more coordinated efforts.

Silicon reduces toxicity and accumulation of arsenic and cadmium in cereal crops: A meta-analysis, mechanism, and perspective study

Arsenic (As) and cadmium (Cd) are two toxic metal(loid)s that pose significant risks to food security and human health. Silicon (Si) has attracted substantial attention because of its positive effects on alleviating the toxicity and accumulation of As and Cd in crops. However, our current knowledge of the comprehensive effects and detailed mechanisms of Si amendment is limited. In this study, a global meta-analysis of 248 original articles with over 7000 paired observations was conducted to evaluate Si-mediated effects on growth and As and Cd accumulation in rice (Oryza sativa L.), wheat (Triticum aestivum L.), and maize (Zea mays L.). Si application increases the biomass of these crops under As and/or Cd contamination. Si amendment also decreased shoot As and Cd accumulation by 24.1 % (20.6 to 27.5 %) and 31.9 % (29.0 to 31.9 %), respectively. Furthermore, the Si amendment reduced the human health risks posed by As (2.6 %) and Cd (12.9 %) in crop grains. Si-induced inhibition of Cd accumulation is associated with decreased Cd bioavailability and the downregulation of gene expression. The regulation of gene expression by Si addition was the driving factor limiting shoot As accumulation. Overall, our analysis demonstrated that Si amendment has great potential to reduce the toxicity and accumulation of As and/or Cd in crops, providing a scientific basis for promoting food safety globally.

Biological roles of soil microbial consortium on promoting safe crop production in heavy metal(loid) contaminated soil: A systematic review

Heavy metal(loid) (HM) pollution of agricultural soils is a growing global environmental concern that affects planetary health. Numerous studies have shown that soil microbial consortia can inhibit the accumulation of HMs in crops. However, our current understanding of the effects and mechanisms of inhibition is fragmented. In this review, we summarise extant studies and knowledge to provide a comprehensive view of HM toxicity on crop growth and development at the biological, cellular and the molecular levels. In a meta-analysis, we find that microbial consortia can improve crop resistance and reduce HM uptake, which in turn promotes healthy crop growth, demonstrating that microbial consortia are more effective than single microorganisms. We then review three main mechanisms by which microbial consortia reduce the toxicity of HMs to crops and inhibit HMs accumulation in crops: 1) reducing the bioavailability of HMs in soil (e.g. biosorption, bioaccumulation and biotransformation); 2) improving crop resistance to HMs (e.g. facilitating the absorption of nutrients); and 3) synergistic effects between microorganisms. Finally, we discuss the prospects of microbial consortium applications in simultaneous crop safety production and soil remediation, indicating that they play a key role in sustainable agricultural development, and conclude by identifying research challenges and future directions for the microbial consortium to promote safe crop production.

Enhancing soil ecological security through phytomanagement of tailings in erosion-prone areas

Revegetation is effective in improving soil quality in ecologically fragile areas. However, little is known about the impact of diverse phytomanagement strategies of tailings on soil quality and ecological security in erosion-prone areas. We investigated the water stability, soil aggregate nutrients, and the risk of heavy metal contamination of abandoned tailings under phytomanagement and in adjacent bare land on the Loess Plateau. The results showed that phytomanagement significantly enhanced soil aggregate stability, as demonstrated by higher contents of soil organic carbon (SOC), glomalin-related soil protein (GRSP), aromatic-C, and alkene-C in macro-aggregates. The pollution load index (PLI) and ecological risk index (RI) of soil heavy metals were lower in shrub/herbaceous mixed forests than in natural grasslands and planted forests. The risk of heavy metal contamination was higher in macro-aggregates (>0.25 mm) than in micro-aggregates (<0.25 mm) and was significantly and positively correlated with the SOC and GRSP contents of the aggregates. Our study demonstrates that soil aggregate quality is closely related to the fate of heavy metals. Diversified tailing revegetation measures can improve soil quality and ensure ecological security.

Vitis Myb14 confer cold and drought tolerance by activating lipid transfer protein genes expression and reactive oxygen species scavenge

The R2R3 Myb transcription factor exhibits a wide range of functions and participates in various biological processes in plant development, secondary metabolism, and abiotic stress tolerance, among others. Vitis Myb14 initially identified for its involvement in resveratrol synthesis in grapevines. In this study, we investigate its role in abiotic stress tolerance. Significant differences in expression were observed between two grape varieties, Vitis amurensis (Cold-hardy) and V. vinifera (Cold-sentitive), under abiotic and hormone treatments. Both VvMyb14 and VaMyb14 demonstrated responsiveness to cold, drought and high salt treatment, but VaMyb14 exhibited a quicker and more pronounced response. To investigate further, we overexpressed VaMyb14 in A. thalina and found that VaMyb14 OE plants showed significantly enhanced cold and drought tolerance compared to wild-type plants. Additionally, the transgenic lines exhibited increased antioxidant enzyme activity, particularly POD activity, and reduced MDA content. Microarray analysis of VaMyb14 OE plants revealed up-regulation of several ABA metabolism and signal transduction genes, including several LTPs, PP2Cs, RD29B, COR78 and other structural genes, indicating that VaMyb14 has the capacity to reprogram a significant signaling pathway. Furthermore, comparative mRNA sequencing profiling of 35S:VaMyb14 grapevine callus indicated its involvement its function involved in ROS scavenging and ABA signaling. These findings collectively demonstrate that Vitis Myb14 serves as a critical regulator in grapevine stress responses, contributing to improved defense against necrotrophic pathogens, enhanced phytoalexin resveratrol production, and increased drought or cold tolerance.

Deciphering microbiomes dozens of meters under our feet and their edaphoclimatic and spatial drivers

Microbes inhabiting deep soil layers are known to be different from their counterpart in topsoil yet remain under investigation in terms of their structure, function, and how their diversity is shaped. The microbiome of deep soils (>1 m) is expected to be relatively stable and highly independent from climatic conditions. Much less is known, however, on how these microbial communities vary along climate gradients. Here, we used amplicon sequencing to investigate bacteria, archaea, and fungi along fifteen 18-m depth profiles at 20-50-cm intervals across contrasting aridity conditions in semi-arid forest ecosystems of China's Loess Plateau. Our results showed that bacterial and fungal α diversity and bacterial and archaeal community similarity declined dramatically in topsoil and remained relatively stable in deep soil. Nevertheless, deep soil microbiome still showed the functional potential of N cycling, plant-derived organic matter degradation, resource exchange, and water coordination. The deep soil microbiome had closer taxa-taxa and bacteria-fungi associations and more influence of dispersal limitation than topsoil microbiome. Geographic distance was more influential in deep soil bacteria and archaea than in topsoil. We further showed that aridity was negatively correlated with deep-soil archaeal and fungal richness, archaeal community similarity, relative abundance of plant saprotroph, and bacteria-fungi associations, but increased the relative abundance of aerobic ammonia oxidation, manganese oxidation, and arbuscular mycorrhizal in the deep soils. Root depth, complexity, soil volumetric moisture, and clay play bridging roles in the indirect effects of aridity on microbes in deep soils. Our work indicates that, even microbial communities and nutrient cycling in deep soil are susceptible to changes in water availability, with consequences for understanding the sustainability of dryland ecosystems and the whole-soil in response to aridification. Moreover, we propose that neglecting soil depth may underestimate the role of soil moisture in dryland ecosystems under future climate scenarios.

New perspectives on microbiome and nutrient sequestration in soil aggregates during long-term grazing exclusion

Grazing exclusion alters grassland soil aggregation, microbiome composition, and biogeochemical processes. However, the long-term effects of grazing exclusion on the microbial communities and nutrient dynamics within soil aggregates remain unclear. We conducted a 36-year exclusion experiment to investigate how grazing exclusion affects the soil microbial community and the associated soil functions within soil aggregates in a semiarid grassland. Long-term (36 years) grazing exclusion induced a shift in microbial communities, especially in the <2 mm aggregates, from high to low diversity compared to the grazing control. The reduced microbial diversity was accompanied by instability of fungal communities, extended distribution of fungal pathogens to >2 mm aggregates, and reduced carbon (C) sequestration potential thus revealing a negative impact of long-term GE. In contrast, 11-26 years of grazing exclusion greatly increased C sequestration and promoted nutrient cycling in soil aggregates and associated microbial functional genes. Moreover, the environmental characteristics of microhabitats (e.g., soil pH) altered the soil microbiome and strongly contributed to C sequestration. Our findings reveal new evidence from soil microbiology for optimizing grazing exclusion duration to maintain multiple belowground ecosystem functions, providing promising suggestions for climate-smart and resource-efficient grasslands.

[Spatial autocorrelation and related factors of stroke mortality in Zhejiang Province based on spatial panel model in 2015-2020]

Objective: To explore the spatial autocorrelation and macro influencing factors of stroke mortality in Zhejiang Province in 2015-2020 and provide a scientific basis for stroke prevention and control strategy. Methods: The data on stroke death were obtained from Zhejiang Chronic Disease Surveillance System. The spatial distribution of stroke mortality was explored by mapping and spatial autocorrelation analysis. The spatial panel model analyzed the correlation between stroke mortality and socioeconomic and healthcare factors. Results: From 2015 to 2020, the average stroke mortality was 68.38/100 thousand. The standard mortality of stroke was high in the areas of east and low in the west, high in the south and low in the north. Moreover, positive spatial autocorrelation was observed (Moran's I=0.274-0.390, P<0.001). Standard mortality of stroke was negatively associated with per capita gross domestic product (GDP) (β=-0.370, P<0.001), per capita health expenditure (β=-0.116, P=0.021), number of beds per thousand population (β=-0.161, P=0.030). Standard mortality of ischemic stroke was negatively associated with per capita GDP (β=-0.310, P=0.002) and standard management rate of hypertension (β=-0.462, P=0.011). Standard mortality of hemorrhagic stroke was negatively associated with per capita GDP (β=-0.481, P<0.001), per capita health expenditure (β=-0.184, P=0.001), number of beds per thousand population (β=-0.288, P=0.001) and standard management rate of hypertension (β=-0.336, P=0.029). Conclusions: A positive spatial correlation existed between stroke mortality in Zhejiang Province in 2015-2020. We must focus more on preventing and controlling strokes in relatively backward economic areas. Moreover, to reduce the mortality of stroke, increasing the investment of government medical and health funds, optimizing the allocation of medical resources, and improving the standard management rate of hypertension are important measures.

[Analysis of disease composition and primary surgical procedures in pediatric secondary glaucoma inpatients: a single-center study]

Objective: To analyze the disease composition and primary surgical procedures in pediatric inpatients with secondary glaucoma. Methods: A retrospective case series study was conducted. Clinical data of children aged≤16 years with secondary glaucoma who were admitted to the Zhongshan Ophthalmic Center, Sun Yat-sen University, between January 1, 2017, and December 31, 2021, were included. The patients were classified according to the Childhood Glaucoma Research Network (CGRN) classification system, and their diagnoses, underlying factors, gender, age of onset, affected eye(s), age and type of initial surgery, and ophthalmic examination data were analyzed. Statistical analysis was performed using Kruskal-Wallis rank sum test and χ2 test. Results: A total of 540 patients (744 eyes) were included in this study, comprising 319 males (59.1%) and 221 females (40.9%). Unilateral disease was observed in 336 cases (62.2%), while bilateral involvement was present in 204 cases (37.8%). The age of onset was 4.0 (0.0, 9.0) years, and the median age of the first anti-glaucoma surgery was 5.0 (0.7, 10.0) years. Among them, there were 195 cases (36.1%) of secondary glaucoma associated with non-acquired ocular anomalies (SCG-O), with a median age of onset of 0.0 (0.0, 4.0) years, and 97 of these cases (49.7%) were male. secondary glaucoma associated with non-acquired systemic disease or syndrome (SCG-S) were observed in 68 cases (12.6%), with a median age of glaucoma onset of 0.1 (0.0, 4.0) years, and 47 of these cases (69.1%) were male. Secondary glaucoma associated with acquired conditions (SCG-A) accounted for 192 cases (35.6%), with a median age of onset of 9.0 (5.0, 13.0) years, and 125 of these cases (65.1%) were male. There were 85 cases (15.7%) of secondary glaucoma following cataract surgery (SCG-C), with a median age of onset of 3.0 (0.8, 7.0) years, and 50 of these cases (58.8%) were male. Male patients were predominant in SCG-S and SCG-A, with 47 cases (69.1%) and 125 cases (65.1%), respectively (χ2=9.94, 17.52; P=0.002,<0.001). Except for SCG-O, all other types of pediatric secondary glaucoma predominantly affected only one eye: SCG-S in 52 cases (76.5%), SCG-A in 128 cases (66.7%), and SCG-C in 54 cases (63.5%) (χ2=19.06, 21.33, 6.22; all P<0.05). The highest proportion of SCG-O was attributed to congenital ectropion uveae (46 cases, 23.6%). Sturge-Weber syndrome was the most common SCG-S (45 cases, 66.3%), while SCG-A mostly resulted from trauma (59 cases, 30.8%) and corticosteroid use (56 cases, 29.2%). Trabeculectomy (211 eyes, 30.8%) and glaucoma drainage device implantation (197 eyes, 28.7%) were the most frequently performed primary surgical procedures. Conclusions: SCG-O and SCG-A were found to be common types of pediatric secondary glaucoma. The age of onset and the choice of primary anti-glaucoma surgical procedures varied among different types of pediatric secondary glaucoma. However, overall, trabeculectomy and glaucoma drainage device implantation were the primary surgical procedures predominantly employed.

Microbial communities in terrestrial surface soils are not widely limited by carbon

Microbial communities in soils are generally considered to be limited by carbon (C), which could be a crucial control for basic soil functions and responses of microbial heterotrophic metabolism to climate change. However, global soil microbial C limitation (MCL) has rarely been estimated and is poorly understood. Here, we predicted MCL, defined as limited availability of substrate C relative to nitrogen and/or phosphorus to meet microbial metabolic requirements, based on the thresholds of extracellular enzyme activity across 847 sites (2476 observations) representing global natural ecosystems. Results showed that only about 22% of global sites in terrestrial surface soils show relative C limitation in microbial community. This finding challenges the conventional hypothesis of ubiquitous C limitation for soil microbial metabolism. The limited geographic extent of C limitation in our study was mainly attributed to plant litter, rather than soil organic matter that has been processed by microbes, serving as the dominant C source for microbial acquisition. We also identified a significant latitudinal pattern of predicted MCL with larger C limitation at mid- to high latitudes, whereas this limitation was generally absent in the tropics. Moreover, MCL significantly constrained the rates of soil heterotrophic respiration, suggesting a potentially larger relative increase in respiration at mid- to high latitudes than low latitudes, if climate change increases primary productivity that alleviates MCL at higher latitudes. Our study provides the first global estimates of MCL, advancing our understanding of terrestrial C cycling and microbial metabolic feedback under global climate change.

Nitrogen removal in improved subsurface wastewater infiltration system: Mechanism, microbial indicators and the limitation of phosphorus

To enhance the nitrogen removal capacity, scrap iron filings and Si-Al porous clay mineral material (PCMW) was used to improve a subsurface wastewater infiltration system (SWIS). The results showed TN and NH₄⁺-N removal efficiencies of improved SWIS were 20.72% and 5.49% higher than those of the control SWIS, respectively. Based on the response of the removal performance, microbial community and function analysis of 16s rRNA amplicon sequencing results, the amending soil matrix substantially enriched the nitrogen removal bacteria (Rhizobiales_Incertae_Sedis and Gemmatimonadaceae), and significantly improved the activities of key enzymes (Hao, NasAB, NarGHI, NirK, NorBC, NirA and NirBD), particularly at co-occurrence zone of nitrification and denitrification (70-130 cm depth). The amending soil matrix not only extended the growth space of microbes, but also provided additional electrons and carbon sources for denitrifying bacteria by regulating the structure and function of the microbial community. In addition, amending soil matrix could enhance phosphate metabolism genes and phosphate solubilizing microbes in the denitrification zone by increasing the phosphorus source, thus strengthening nitrogen metabolism. Nitrospiraceae, Rhizobiales_Incertae_Sedis and Gemmatimonadaceae related to nitrogen removal and Bacillaceae with phosphate-solubilizing ability could be used as microbial indicators of nitrogen removal in SWISs. The reciprocal action of environmental on microbial characteristics exhibited microbial functional were related to DO, Fe²⁺, TOC, TP, TN, NH₄⁺-N and NO₃^--N. Those could be used as physicochemical and biological indicators for application and monitoring of SWIS. In conclusion, this study provided a low-cost and efficient enhancement approach for the application of SWIS in decentralized domestic sewage treatment, and furnished theoretical support for subsequent applications.

Nanoplasma resonance condition in the middle-infrared spectral range

The resonance-absorption condition in the laser-nanoplasma interactions has been considered to follow the wavelength dependence of the critical plasma density. We experimentally demonstrate that this assumption fails in the middle-infrared spectral range, while it is valid for visible and near-infrared wavelengths. A thorough analysis supported by molecular dynamic (MD) simulations indicates that the observed transition in the resonance condition is caused by the reduction of the electron scattering rate and the associated increase of the cluster outer-ionization contribution. An expression for the nanoplasma resonance density is derived based on experimental results and MD simulations. The findings are important for a broad range of plasma experiments and applications, since the extension of the laser-plasma interaction studies to longer wavelengths has become increasingly topical.

Microplastics may increase the environmental risks of Cd via promoting Cd uptake by plants: A meta-analysis

Microplastics (MPs) and cadmium (Cd) are widely distributed in soil ecosystems, posing a potential threat to agricultural production and human health. However, the coupled effects of MPs and Cd in soil-plant systems remain largely unknown, especially on a large scale. In this study, a meta-analysis was conducted to evaluate the influence of MPs on plant growth and Cd accumulation under the Cd contamination conditions. Our results showed that MPs had significantly negative effects on shoot biomass (a decrease of 11.8 %) and root biomass (a decrease of 8.79 %). MPs also significantly increased Cd accumulation in the shoots and roots by 14.6 % and 13.5 %, respectively, revealing that MPs promote plant Cd uptake. Notably, polyethylene displayed a stronger promoting effect (an increase of 29.4 %) on Cd accumulation among these MP types. MPs induced a significantly increase (9.75 %) in concentration of soil available Cd and a slight decrease in soil pH, which may be the main driver promoting plant Cd uptake. MP addition posed physiological toxicity risks to plants by inhibiting photosynthesis and enhancing oxidative damage, directly demonstrating that MPs in combination with Cd can pose synergetic toxicity risks to plants. We further noted that MPs altered microbial diversity, likely influencing Cd bioavailability in soil-plant systems. Overall, our study has important implications for the combined impacts of Cd and MPs on plants and provides new insights into developing guidelines for the sustainable use of MPs in agriculture.

Crop residue return sustains global soil ecological stoichiometry balance

Although soil ecological stoichiometry is constrained in natural ecosystems, its responses to anthropogenic perturbations are largely unknown. Inputs of inorganic fertilizer and crop residue are key cropland anthropogenic managements, with potential to alter their soil ecological stoichiometry. We conducted a global synthesis of 682 data pairs to quantify the responses of soil carbon (C), nitrogen (N), and phosphorus (P) and grain yields to combined inputs of crop residue plus inorganic fertilizer compared with only inorganic fertilizer application. Crop residue inputs enhance soil C (10.5%-12%), N (7.63%-9.2%), and P (2.62%-5.13%) contents, with an increase in C:N (2.51%-3.42%) and C:P (7.27%-8.00%) ratios, and grain yields (6.12%-8.64%), indicating that crop residue alleviated soil C limitation caused by inorganic fertilizer inputs alone and was able to sustain balanced stoichiometry. Moreover, the increase in soil C and C:N(P) ratio reached saturation in ~13-16 years after crop residue return, while grain yield increase trend discontinued. Furthermore, we identified that the increased C, N, and P contents and C:N(P) ratios were regulated by the initial pH and C content, and the increase in grain yield was not only related to soil properties, but also negatively related to the amount of inorganic N fertilizer input to a greater extent. Given that crop residual improvement varies with soil properties and N input levels, we propose a predictive model to preliminary evaluate the potential for crop residual improvement. Particularly, we suggest that part of the global budget should be used to subsidize crop residue input management strategies, achieving to a win-win situation for agricultural production, ecological protection, and climate change mitigation.

Synergistic interplay between Azospirillum brasilense and exogenous signaling molecule H2S promotes Cd stress resistance and growth in pak choi (Brassica chinensis L.)

Inoculation with growth-promoting rhizobacteria inoculation and the addition of exogenous signaling molecules are two distinct strategies for improving heavy metal resistance and promoting growth in crops through several mechanisms. However, whether rhizobacteria and phyllosphere signaling molecules can act synergistically alleviate heavy metal stress and promote growth and the mechanisms underlying these effects remain unclear. Here, a novel strategy involving the co-application of growth-promoting rhizobacteria and an exogenous signaling molecule was developed to reduce cadmium (Cd) phytotoxicity and promote pak choi growth in Cd-contaminated soil. We found that the co-application of Azospirillum brasilense and hydrogen sulfide (H₂S) resulted in significant improvements in shoot biomass and antioxidant enzyme content and a decline in the levels of Cd translocation factors. In addition, this co-application significantly improved pak choi Cd resistance. Furthermore, we observed a significant negative correlation between abscisic acid concentration and Cd content of pak choi and a positive correlation between H₂S concentration and biomass. These findings revealed that the co-application of rhizobacteria and exogenous signaling molecules synergistically promoted the growth of vegetable crops subjected to heavy metal stress. Our results may serve as a guide for improving the food safety of crops grown in soil contaminated with heavy metals.

Generic CD-MUSIC-eSGC model parameters to predict the surface reactivity of iron (hydr)oxides

The surface reactivity of iron (hydr)oxides plays a crucial role in controlling their interfacial reactions, for which various surface complexation models have been developed. The diversity of mineralogical properties of iron (hydr)oxides has resulted in a redundancy of model parameters, which hampers the modeling of iron (hydr)oxides in soils and sediments, where goethite, hematite and ferrihydrite dominate the iron (hydr)oxide mass fraction. To capture their combined surface reactivity, optimized generic protonation parameters of the Charge Distribution-Multisite Complexation (CD-MUSIC) extended-Stern-Gouy-Chapman (eSGC) model were derived by reanalyzing literature datasets and tested with some newly synthesized iron (hydr)oxides. It was observed that the proton and monovalent ion affinity constants of the different iron (hydr)oxides were located in a narrow range. For the singly- and triply-coordinated hydroxyl sites the obtained generic log(affinity constants) were 8.3 and 11.7 for the protonation reaction and -0.5 for the reaction with the monovalent background ions. Their combination with fixed site densities of singly-/triply-coordinated hydroxyl sites of 3.45/2.70, 5.00/2.50, and 5.80/1.40 sites/nm² for goethite, hematite, and ferrihydrite, respectively, provided good results. The Stern layer capacitances of the inner and outer Stern layers were set equal and could be acquired by an empirical correlation with the sample specific surface area (SSA). The CD-MUSIC-eSGC model with the generic model parameters enables good quality predictions of the proton reactivity of iron (hydr)oxides in 1:1 electrolyte solutions regardless of the sample heterogeneity. The advantages of the generic CD-MUSIC-eSGC model are twofold: (1) protonation of iron (hydr)oxides can be described without making use of spectroscopic measurements and proton titrations, and (2) the model calculations are greatly simplified.

Comparative transcriptomic analysis reveals candidate genes for seasonal breeding in the male Lion-Head goose

1. Due to seasonal breeding, geese breeds from Southern China have low egg yield. The genetic makeup underlying performance of local breeds is largely unknown, and few studies have investigated this problem. This study integrated 21 newly generated and 50 publicly existing RNA-seq libraries, representing the hypothalamus, pituitary and testis, to identify candidate genes and importantly related pathways associated with seasonal breeding in male Lion-Head geese.2. In total, 19, 119 and 302 differentially expressed genes (DEGs) were detected in the hypothalamus, pituitary and testis, respectively, of male Lion-Head geese between non-breeding and breeding periods. These genes were significantly involved in the neuropeptide signalling pathway, gland development, neuroactive ligand-receptor interaction, JAK-STAT signalling pathway, cAMP signalling pathway, PI3K-Akt signalling pathway and Foxo signalling pathway.3. By integrating another 50 RNA-seq samples 4, 18 and 40 promising DEGs were confirmed in hypothalamus, pituitary and testis, respectively.4. HOX genes were identified as having important roles in the development of testis between non-breeding and breeding periods of male Lion-Head geese.

Microplastics addition reduced the toxicity and uptake of cadmium to Brassica chinensis L

The coexistence of microplastics (MPs) and toxic metal contaminants in soils is becoming increasingly common, thereby posing serious threat to soil-plant systems. Cadmium (Cd) is the most common metal contaminant in soil and can easily combine with MPs, thereby altering its bioavailability. However, few studies have focused on the co-pollution of MPs and Cd, particularly the complex phytotoxicity caused by their interaction and the effect of co-exposure on Cd uptake in plants. We conducted pot experiments to compare the effects of exposure to polystyrene (PS) and Cd, as well as the effects of co-exposure (PS + Cd), on the physiological characteristics of Brassica chinensis L. and explored the regulatory factors of MPs on Cd uptake in plant tissues. The results showed that plant biomass, photosynthetic parameters, and chlorophyll content significantly decreased (p < 0.05) with increasing PS doses under treatment with MPs alone. Although the negative effects of PS and Cd co-exposure on plants were higher than those of PS alone, however, the addition of MPs reduced the toxicity effects of Cd on plants and decreased the uptake and accumulation of Cd by plants compared with the Cd treatment alone. Furthermore, plants can resist the increased malondialdehyde content and oxidative stress induced by PS and Cd exposure by increasing the activities of superoxide dismutase and peroxidase. Under the PS + Cd treatment, linear models showed that soil organic carbon and sucrase activity were the key variables affecting Cd uptake by plant shoots and roots, respectively. The results of the partial least squares path modeling further showed that PS indirectly affected Cd uptake by B. chinensis by significantly affecting the physicochemical properties of soil, Cd concentration, and enzyme activity. Our results provide a new perspective and an important reference for further understanding the effects of MPs on the bioavailability and fate of heavy metals.

Microbial metabolic limitation and carbon use feedback in lead contaminated agricultural soils

Potentially toxic elements (PTEs) pollution causes a great threat to microbial metabolism, which plays a vital role in studying soil nutrient cycling and predicting carbon (C) storage in agroecosystems. However, the responses of microbial metabolism characteristic to heavy metal contamination and the mechanisms through which microbial metabolism mediate nutrient cycling and C dynamics in contaminated soil remain elusive. Here, we performed an incubation experiment over 80 days to investigate the variations in microbial metabolic limitation under various Pb levels (0, 100, 500, 800, 1500, 2000, and 3000 mg Pb kg^-1 dry soil) in cropland soil using extracellular enzymatic stoichiometry, and to reveal the impact of Pb stress on soil C storage by associating with microbial metabolic quotients (qCO₂) and C use efficiency (CUE). The results showed microbial relative C limitation and phosphorus (P) limitation were observed in Pb-contaminated soils. Pb addition enhanced the microbial relative C limitation by approximately 7.3%, while decreasing the P limitation by approximately 12.3%. Furthermore, Pb addition led to higher qCO₂ (from 8.75 to 108 μg C kg^-1 MBC^-1 d^-1) duo to the increase of microbial relative C limitation, suggesting that the more CO₂ was released of per unit of microbial biomass C. The increase of microbial relative C limitation reduced CUE (from 0.35 to 0.10) because of the change in microbial metabolism from growth to respiration maintenance under Pb stress. Consequently, the CUE and qCO₂ together determined the loss of soil C. Our study reveals that microbial relative C limitation is the dominant driver of soil C loss and provides important knowledge of microbial metabolic limitation regulating soil C turnover in PTEs-contaminated agricultural soils.

[Identification and functional analysis of combined oxidative phosphorylation deficiency 28 gene mutation]

Objective: To report a case of combined oxidative phosphorylation deficiency 28 (COXPD28) in China, identified the pathogenic mutation and explored the pathogenic mechanism preliminarily. Methods: The clinical characteristics of a patient with COXPD28 were retrospectively analyzed and the pathogenic mutations were identified by mitochondrial gene sequencing and whole exome sequencing. The wild-type and mutant plasmids of pathogenic genes were constructed, and effect of mutation on protein expression by quantitative real-time PCR (qPCR) and Western blot were evaluated. Statistical methods mainly used one-way ANOVA and LSD test. Results: A 21 year old female patient presented with lactic acid poisoning due to repeated chest distress and wheezing since childhood. The sequencing of the whole exon group gene found that solute carrier family 25 member 26 (SLC25A26) gene had a compound heterozygous mutation (c.34G>C, p.A12P; c.197C>A, p.A66E), which was the first report in China. In vitro function test showed that the expression levels of SLC25A26 mRNA and S-adenosylmethionine carrier (SAMC) protein in cells transfected with SLC25A26 mutant plasmid were significantly lower than those transfected with wild type plasmid. The p.A66E mutant plasmid reduced the expression level of SLC25A26 mRNA and SAMC protein to 6% and 26% of wild type plasmids respectively (both P<0.001), while p.A12P mutant plasmid decreased to 62% and 82% of wild type plasmids respectively (P<0.001, P=0.044). When the double mutant (p.A66E+p.A12P) plasmids were co-transfected, the expression levels of SLC25A26 mRNA and SAMC protein decreased to 47% and 57% of the wild type plasmids, respectively (P<0.001, P=0.001). Conclusion: The pathogenic mutation gene of this patient with COXPD28 is SLC25A26 gene mutation (p.A66E, p.A12P), which causes the decrease of SLC25A26 expression level, mitochondrial oxidative phosphorylation dysfunction, and induces COXPD28.

Implementing nitrous oxide cracking technology in the labour ward to reduce occupational exposure and environmental emissions: a quality improvement study. Anaesthesia 2022;77:1228-1236. [PMID: 36108342 DOI: 10.1111/anae.15838]

Nitrous oxide, a potent greenhouse gas, is a common labour analgesic. One method which may reduce its carbon footprint is to 'crack' the exhaled gas into nitrogen and oxygen using catalytic destruction. In this quality improvement project, based on environmental monitoring and staff feedback, we assessed the impact of nitrous oxide cracking technology in the maternity setting. Mean ambient nitrous oxide levels were recorded during the final 30 minutes of uncomplicated labour in 36 cases and plotted on a run chart. Interventions were implemented in four stages, comprising: stage 1, baseline (12 cases); stage 2, cracking with nitrous oxide delivered and scavenged via a mouthpiece (eight cases); stage 3, cracking with nitrous oxide via a facemask with an air-filled cushion (eight cases); stage 4, cracking with nitrous oxide via a low-profile facemask, and enhanced coaching on the use of the technology (eight cases). The median ambient nitrous oxide levels were 71% lower than baseline in stage 2 and 81% lower in stage 4. Staff feedback was generally positive, though some found the technology to be cumbersome; successful implementation relies on effective staff engagement. Our results indicate that cracking technology can reduce ambient nitrous oxide levels in the obstetric setting, with potential for reductions in environmental impacts and occupational exposure.

Pollution characteristics and health risk assessment of potentially toxic elements in soils around China's gold mines: a meta-analysis

Since toxic element pollution is widespread in soils near gold mines due to increasing mining activities, the adverse effects of potentially toxic elements (PTEs) in the soils on ecological systems and human health cannot be ignored. However, assessments of PTE pollution in soils and their ecological-health risks on a national scale are still limited. Here, the concentrations of eight PTEs in soils near gold mines throughout China were obtained from published articles. Based on these data, the pollution levels and ecological-health risks of the eight PTEs in soils were comprehensively estimated. The results showed that the average contents of As, Cr, Cd, Pb, Hg, Cu, Ni, and Zn were 81.62, 79.82, 1.04, 206.03, 2.05, 40.82, 71.82, and 130.42 mg kg^-1, respectively, which exceeded the corresponding background values for soils. Most of the examined soils were heavily polluted by Hg and Cd, and higher pollution levels were found in the Henan and Shaanxi Provinces than in other regions. The average potential ecological risk value of all PTEs was 2534.71, indicating the presence of very high risks. Contribution of Hg to the potential ecological risk was more than 80%. For adults, all hazard index (HI) values of noncarcinogenic risks were below the safe level of 1.00. For children, none of the HI values exceeded the safe level, with the exception of As (HI = 1.81); nevertheless, four PTEs (As, Cr, Cu, and Ni) presented unacceptable carcinogenic risks. This study provides scientific basis for controlling PTE contamination and reducing the health risks in soils near gold mines worldwide.

Arbuscular mycorrhizal fungi: Effects on secondary metabolite accumulation of traditional Chinese medicines

Traditional Chinese medicine (TCM) has played a pivotal role in maintaining the health of people, and the intrinsic quality of TCM is directly related to the clinical efficacy. The medicinal ingredients of TCM are derived from the secondary metabolites of plant metabolism and are also the result of the coordination of various physiological activities in plants. Arbuscular mycorrhizal fungi (AMF) are among the most ubiquitous plant mutualists that enhance the growth and yield of plants by facilitating the uptake of nutrients and water. Symbiosis of AMF with higher plants promotes growth and helps in the accumulation of secondary metabolites. However, there is still no systematic analysis and summation of their roles in the application of TCM, biosynthesis and accumulation of active substances of herbs, as well as the mechanisms. AMF directly or indirectly affect the accumulation of secondary metabolites of TCM, which is the focus of this review. First, in this review, the effects of AMF symbiosis on the content of different secondary metabolites in TCM, such as phenolic acids, flavonoids, alkaloids and terpenoids, are summarized. Moreover, the mechanism of AMF regulating the synthesis of secondary metabolites was also considered, in combination with the establishment of mycorrhizal symbionts, response mechanisms of plant hormones, nutritional elements and expression of key enzyme their activities. Finally, combined with the current application prospects for AMF in TCM, future in-depth research is planned, thus providing a reference for improving the quality of TCM. In this manuscript, we review the research status of AMF in promoting the accumulation of secondary metabolites in TCM to provide new ideas and methods for improving the quality of TCM.

[Occupational stress of air traffic controllers and its influencing factors]

Objective: To investigate the occupational stress status of air traffic controllers (ATC) and analyze its influencing factors. Methods: By using cluster sampling method, 457 ATCs in an air traffic management bureau were selected as the investigation objects. The job content questionnaire (JCQ) and the effort reward imbalance questionnaire (ERI) were used to measure work requirements independent imbalance type and ERI type occupational stress separately and analyze the influencing factors. Results: Of the 457 ATCs, 81.84% (374/457) ATGs had work requirements independent imbalance type of occupational stress and 84.46% (386/457) ATGs had ERI type occupational stress. Univariate analysis showed that the factors of marital status, degree of education, age, length of service, title, job post, family monthly income, views on regular training, occurrence of emergency or unsafe events in last month and monthly night shift frequency had various degrees of influence on the different factor scores of JCQ and ERI (P<0.01) . Logistic regression analysis showed that the level of JCQ type occupational stress of ATCs with junior titles and probationers was higher than those of intermediate/senior titles (P=0.000, 0.000) ; The ERI type occupational stress of probationers and junior titles ATCs was lower than those with intermediate/senior titles (P=0.000) . The ERI and JCQ type occupational stress level of tower post ATCs was higher than that of other two job post ATCs (P=0.001, 0.000, 0.000, 0.000) . The ATCs considering regular training had more disadvantages than advantages showed lower ERI type occupational stress level than those considering more advantages than disadvantages (P=0.000) . The ERI type occupational stress level of ATCs who experienced emergency or unsafe events in last month was higher than those who didn't (P=0.007) . Conclusion: A large proportion of ATCs had occupational stress. Management should adjust its policies and pay were attention to occupational stress of ATLs.

Sequestration of heavy metals in soil aggregates induced by glomalin-related soil protein: A five-year phytoremediation field study

Glomalin-related soil protein (GRSP) is an essential bioactive component that may respond to heavy metal stress; however, its exact influence on metal bioavailability and the associated mechanism remains poorly understood. This study investigated the speciation and distribution of heavy metals in soil aggregates associated with GRSP through macroscopic and microscopic approaches. A field study showed that the metal ions were distributed to the macro-aggregate fraction by partitioning the particle size classes during phytoremediation. Partial least squares path modeling (PLS-PM) demonstrated that the heavy metal bioavailability was negatively affected by aggregate stability (61.5%) and GRSP content (52.8%), suggesting that the soil aggregate properties regarding GRSP were vital drivers in mitigating environmental risk closely associated with toxic metal migration in soil-plant systems. The nonideal competitive adsorption (NICA)-Donnan model fitting suggested that GRSP were rich in acid site density, and the complexation with deprotonated groups dominated the speciation of heavy metals in soil. Further, the microfocus X-ray absorption/fluorescence spectroscopy analysis indicated that GRSP might promote the formation of stable metal species by binding with sulfur-containing sites. This study highlights the role of GRSP in heavy metal sequestration in contaminated soils, providing new guidance on the GRSP intervention for phytoremediation strategies.

A global meta-analysis of heavy metal(loid)s pollution in soils near copper mines: Evaluation of pollution level and probabilistic health risks

With the rapid development of the mining industry, the pollution of heavy metal(loid)s in soils near copper (Cu) mining sites is a significant concern worldwide. However, the pollution status and probabilistic health risks of heavy metal(loid)s of soils associated with Cu mines, have rarely been studied on a global scale. In this study, eight heavy metal(loid) concentrations in soil samples taken near 102 Cu mining sites worldwide were obtained through a literature review. Based on this database, the heavy metal(loid) pollution and ecological risk in soils near Cu mines were evaluated. Most of the study sites exceeded the moderately to heavily polluted levels of Cu and Cd; compared to other regions, higher pollution levels were observed at sites in Oman, China, Australia, and the United Kingdom. Soil pollution by Cd, Pb, and Zn at agricultural sites was higher than that in non-agricultural sites. In addition, these heavy metal(loid)s produced a high ecological risk to soils around Cu mining sites in which the contribution of Cd, Cu, and As reached up to 46.5%, 21.7%, and 18.4%, respectively. The mean hazard indices of the eight heavy metal(loid)s were 0.209 and 0.979 for adults and children, respectively. The Monte Carlo simulation further predicted that 1.40% and 29.9% of non-carcinogenic risk values for adults and children, respectively, exceeded the safe level of 1.0. Moreover, 84.5% and 91.0% of the total cancer risk values for adults and children, respectively, exceeded the threshold of 1E-04. Arsenic was the main contributor to non-carcinogenic risk, while Cu had the highest exceedance of carcinogenic risk. Our findings indicate that the control of Cu, Cd, and As should be prioritized because of their high incidence and significant risks in soils near Cu mines. These results provide valuable inputs for policymakers in designing effective strategies for reducing the exposure of heavy metal(loid)s in this area worldwide.

A review of microplastics in soil: Occurrence, analytical methods, combined contamination and risks

Microplastics (MPs) pollution is becoming a serious environmental issue of global concern. Currently, the effects of MPs on aquatic ecosystems have been studied in detail and in depth from species to communities. However, soils, the largest reservoir of MPs, have been less studied, and little is known about the occurrence, environmental fate and ecological impacts of MPs. Therefore, based on the existing knowledge, this paper firstly focused specifically on the main sources of soil MPs pollution and explored the main reasons for their strong heterogeneity in spatial distribution. Secondly, as a primary prerequisite for evaluating MPs contamination, we systematically summarized the analytical methods for soil MPs and critically compared the advantages and disadvantages of the different methods in the various operational steps. Furthermore, this review highlighted the combined contamination of MPs with complex chemical contaminants, the sorption mechanisms and the associated factors in the soil. Finally, the risks posed by MPs to soil, plants, the food chain and even humans were outlined, and future directions for soil MPs research were proposed, while the urgent need for a unified approach to MPs extraction and identification was emphasized. This study provides a theoretical reference for a comprehensive understanding of the separation of soil MPs and their ecological risk as carriers of pollution.

Dissolved Organic Matter Promotes the Aging Process of Polystyrene Microplastics under Dark and Ultraviolet Light Conditions: The Crucial Role of Reactive Oxygen Species

Microplastics (MPs) interact frequently with dissolved organic matter (DOM) commonly found in the environment, but information on the aging behavior of MPs under the participation of DOM is still lacking. Thus, the polystyrene microplastic (PSMP) aging process with DOM participation was systematically studied by electron paramagnetic resonance spectroscopy, high-performance liquid chromatography, Fourier transform infrared (FTIR) spectroscopy, and two-dimensional correlation spectroscopy analyses under dark and ultraviolet (UV) light conditions. DOM was found to promote electron transfer to generate reactive oxygen species (ROS) under dark conditions and the aging of PSMPs, while the process of DOM generating ROS under UV light was more susceptible to photoelectrons and accelerated the aging process of PSMPs. However, among the four DOM types, fulvic acid (FA) has a more significant promoting effect on the aging process of PSMPs than humic acid, which can be attributed to the stronger conversion ability of FA to semiquinone radicals. Density functional theory calculations are used to describe the difference in the aging process of different structures of plastics with the participation of DOM. This study provides a necessary theoretical basis for the study of the migration of MPs in groundwater and deep surface water.

Occurrence status of microplastics in main agricultural areas of Xinjiang Uygur Autonomous Region, China

A large number of plastic products are used in the process of agricultural production, and the recycling efficiency is low, which leads to the production of a large number of microplastics. Therefore, the microplastic contamination in agricultural areas requires being investigated urgently. In addition, the occurrence characteristics of microplastics are also different in agricultural areas with various land use modes. In this study, the main agricultural areas in Xinjiang are taken as the research object. The abundance of microplastics in the main agricultural areas in Xinjiang ranges from 288 to 1452 items/kg. The shape of microplastics is mainly bulks, and white microplastics account for the highest proportion, and the majority of their sizes are less than 0.5 mm. The risk assessment results show that the contamination risk index of microplastics in this area is 108.92 and the risk level is grade III. The research shows that there is little difference in the abundance of microplastics between paddy field and garden land, which may be because there are few sources of microplastics in the land of these two utilization modes, and the potential pollution sources are similar, such as the atmospheric deposition of microplastics, the falling of fibers on people's clothes during farming, and the agricultural use of sludge. This study can provide a reference for further study on the existing circumstances of microplastics in agricultural areas.

[Hypoxia promotes differentiation of human induced pluripotent stem cells into embryoid bodies in vitro]

OBJECTIVE

To investigate effects of physiological hypoxic conditions on suspension and adherence of embryoid bodies (EBs) during differentiation of human induced pluripotent stem cells (hiPSCs) and explore the underlying mechanisms.

METHODS

EBs in suspension culture were divided into normoxic (21% O₂) and hypoxic (5% O₂) groups, and those in adherent culture were divided into normoxic, hypoxic and hypoxia + HIF-1α inhibitor (echinomycin) groups. After characterization of the pluripotency with immunofluorescence assay, the hiPSCs were digested and suspended under normoxic and hypoxic conditions for 5 days, and the formation and morphological changes of the EBs were observed microscopically; the expressions of the markers genes of the 3 germ layers in the EBs were detected. The EBs were then inoculated into petri dishes for further culture in normoxic and hypoxic conditions for another 2 days, after which the adhesion and peripheral expansion rate of the adherent EBs were observed; the changes in the expressions of HIF-1α, β-catenin and VEGFA were detected in response to hypoxic culture and echinomycin treatment.

RESULTS

The EBs cultured in normoxic and hypoxic conditions were all capable of differentiation into the 3 germ layers. The EBs cultured in hypoxic conditions showed reduced apoptotic debris around them with earlier appearance of cystic EBs and more uniform sizes as compared with those in normoxic culture. Hypoxic culture induced more adherent EBs than normoxic culture (P < 0.05) with also a greater outgrowth rate of the adherent EBs (P < 0.05). The EBs in hypoxic culture showed significantly up-regulated mRNA expressions of β-catenin and VEGFA (P < 0.05) and protein expressions of HIF-1 α, β-catenin and VEGFA (P < 0.05), and their protein expresisons levels were significantly lowered after treatment with echinomycin (P < 0.05).

CONCLUSION

Hypoxia can promote the formation and maturation of suspended EBs and enhance their adherence and post-adherent proliferation without affecting their pluripotency for differentiation into all the 3 germ layers. Our results provide preliminary evidence that activation of HIF-1α/β-catenin/VEGFA signaling pathway can enhance the differentiation potential of hiPSCs.

Global disease burden of COPD from 1990 to 2019 and prediction of future disease burden trend in China

OBJECTIVES

This study aimed to assess and predict the disease burden attributable to chronic obstructive pulmonary disease (COPD) in a timely, comprehensive, and reliable manner, thereby mitigating the health hazards of COPD.

STUDY DESIGN AND METHODS

Data on the disease burden owing to COPD from 1990 to 2019 were extracted from the Global Burden of Disease (GBD) Study 2019. Linear regression analysis was used to calculate the estimated annual percentage change (EAPC) in the age-standardized rates. Non-parametric tests were used for subgroup analysis. The Bayesian age-period-cohot (BAPC) model integrated nested Laplace approximations to predict the disease burden over the next 25 years. Sensitivity analysis was performed using the Norpred APC model.

RESULTS

Globally, the COPD-related age-standardized incidence rate decreased from 216.48/100,000 in 1990 to 200.49/100,000 in 2019, with an EAPC of -0.33. But the number of new cases increased from 8,722,966 in 1990 to 16, 214, 828 in 2019. Trends in prevalence, deaths, and disability-adjusted life years (DALYs) were the same as incidence. There were significant differences in disease burden between the genders and all age groups (P < 0.05) in China. The projections suggested that the COPD-related number of new cases and deaths in China would increase by approximately 1.5 times over the next 25 years.

CONCLUSIONS

The number of incidence, prevalence, deaths, and DALYs had all increased in China in the past and would continue to grow over the next 25 years. Therefore, measures should be taken to target risk factors and high-risk groups.

AB0932 Patient and learner experience in a new set up of a rheum-derm combined care model for psoriatic arthritis

Background

Psoriasis (PsO) and musculoskeletal manifestations are common among patients with psoriatic arthritis (PsA). A shared-care model between rheumatologists and dermatologists has been advocated to promote early diagnosis and improve management care. Data from Asia is scanty. Patients’ and learners’ experience of shared-care models are seldom explored.

Objectives

We described the set-up of a new shared-cared PsA-PsO clinic incorporating service, education and research between rheumatologist and dermatologist for PsA. We describe the patients’ and learners’ experience of this shared-care model.

Methods

A combined care clinic was newly set up in 2019. Referrals were internal through either specialty. Each patient was first seen by a trainee, followed by both a dermatologist and rheumatologist simultaneously in the same consultation room. We collected patients’ and learners’ experience through self-administered survey.

Results

From May 2019 to January 2020, data from 44 visits (55% new referrals, 45% follow-up) from 28 patients were captured in the PsA-PsO clinic. 50% of cases were referred from either specialty. 34% were referred for diagnostic doubts, 66% were for therapeutic issues. 61% of patients continued follow-up in the PsA-PsO clinic, and 39% discharged back to respective care. From patients’ experience rated on scale from 0-10, median (interquartile range, IQR) rating of the care was 8 (7, 8). 69.2% and 96% of patients would recommend the care to others. Free text comments included enhanced convenience, time saving, and having both specialties input on management. From 20 learners (3 medial students, 12 residents, 4 senior residents and one scientist), 95% reported extremely or very beneficial to training, 77.8% reported improved confidence in care for PsA and/or PsO patients. The PsA-PsO clinic was temporally suspended during the Covid-19 viral pandemic since February 2020 due to lack of manpower and not fulfilling the spacing out requirement for infectious control. The service was resumed gradually from May 2021.

Conclusion

Despite challenges, we report the setup of a new care model between dermatologists and rheumatologists for care of patients with psoriatic disease. The care model was well received by patients. Learners from various levels reported benefit from the learning experience.

Disclosure of Interests

Cassandra Hong: None declared, Liwen Fang: None declared, Yi-Wei Yeo: None declared, Haur Yueh Lee: None declared, Andrea Low: None declared, Ying Ying Leung Speakers bureau: Received honorarium from Abbvie, DKSH, Janssen, Novartis and Pfizer.

Microbial metabolic limitation of rhizosphere under heavy metal stress: Evidence from soil ecoenzymatic stoichiometry

Slow nutrient turnover and destructed soil function were the main factors causing low efficiency in phytoremediation of heavy metal (HM)-contaminated soil. Soil ecoenzymatic stoichiometry can reflect the ability of soil microorganisms to acquire energy and nutrients, and drive nutrient cycling and carbon (C) decomposition in HM-contaminated soil. Therefore, for the first time, we used the enzymatic stoichiometry modeling to examine the microbial nutrient limitation in rhizospheric and bulk soil of different plants (Medicago sativa, Halogeton arachnoideus and Agropyron cristatum) near the Baiyin Copper Mine. Results showed that the main pollutants in this area were Cu, Zn, Cd, and Pb, while Cd and Zn have the greatest contribution according to the analysis of pollution load index (PLI). The activities of soil C-, nitrogen (N)-, and phosphorus (P)-acquiring enzymes in the rhizosphere of plants were significantly greater than that in bulk soil. Moreover, microbial C and P limitations were observed in all plant treatments, while the lower limitation was generally in the rhizosphere compared to bulk soil. The HM stress significantly increased microbial C limitation and decreased microbial P limitation, especially in the rhizospheric soil. The partial least squares path modeling (PLS-PM) further indicated that HM concentration has the greatest effects on microbial P limitation (-0.64). In addition, the highest enzyme activities and the lowest P limitation were observed in the rhizospheric and bulk soil of M. sativa, thereby implying that soil microbial communities under the remediation of M. sativa were steadier and more efficient in terms of their metabolism. These findings are important for the elucidation of the nutrient cycling and microbial metabolism of rhizosphere under phytoremediation, and provide guidance for the restoration of HM-contaminated soil.

Environmental and health risk assessment of potentially toxic trace elements in soils near uranium (U) mines: A global meta-analysis

Soil pollution by potentially toxic trace elements (PTEs) near uranium (U) mines arouses a growing interest worldwide. However, nearly all studies have focused on a single site or only a few sites, which may not fully represent the soil pollution status at the global scale. In this study, data of U, Cd, Cr, Pb, Cu, Zn, As, Mn, and Ni contents in U mine-associated soils were collected and screened from published articles (2006-2021). Assessments of pollution levels, distributions, ecological, and human health risks of the nine PTEs were analysed. The results revealed that the average contents of the U, Cd, Cr, Pb, Cu, Zn, As, Mn, and Ni were 39.88-, 55.33-, 0.88-, 3.81-, 3.12-, 3.07-, 9.26-, 1.83-, and 1.17-fold greater than those in the upper continental crust, respectively. The pollution assessment showed that most of the studied soils were heavily polluted by U and Cd. Among them, the U mine-associated soils in France, Portugal, and Bulgaria exhibited significantly higher pollution levels of U and Cd when compared to other regions. The average potential ecological risk value for all PTEs was 3358.83, which indicated the presence of remarkably high risks. Among the PTEs, Cd and U contributed more to the potential ecological risk than the other elements. The health risk assessment showed that oral ingestion was the main exposure route for soil PTEs; and the hazard index (HI) values for children were higher than those for adult males and females. For adult males and females, all hazard index values for the noncarcinogenic risks were below the safe level of 1.00. For children, none of the HI values exceeded the safe level, with the exception of U (HI = 3.56) and As (HI = 1.83), but Cu presented unacceptable carcinogenic risks. This study provides a comprehensive analysis that demonstrates the urgent necessity for treating PTE pollution in U mine-associated soils worldwide.

Phytoremediation of potentially toxic elements (PTEs) contaminated soils using alfalfa (Medicago sativa L.): A comprehensive review

Soil contamination with potentially toxic elements (PTEs) is an increasing environmental problem, posing serious threats to the living organisms. Phytoremediation is a sustainable and highly accepted technology for remediation of PTE-contaminated soils. Alfalfa has been widely adopted for the phytoremediation of PTE-contaminated soils due to its large biomass productivity, high PTE tolerance, and strong capacity to take up PTEs. However, there are still no literature reviews systematically summarized the potential of alfalfa in the phytoremediation. Therefore, we review the available literatures that present its PTE uptake, phytotoxicity, tolerance mechanisms, and aided techniques improving the phytoremediation efficiency. In this review, alfalfa shows high amounts of PTEs accumulation, especially in their root tissue. Meanwhile, the inner mechanisms of PTE tolerance and accumulation in alfalfa are discussed including: (i) the activation of antioxidant enzyme system, (ii) subcellular localization, (iii) production of glutathione, phytochelatins, and proline, and (iv) regulation of gene expression. Indeed, excessive PTE can overcome the defense system, which causes oxidative damage in alfalfa plants, thereby inhibiting growth and physiological processes and weakening the ability of PTE uptake. Till now, several approaches have been developed to improve the tolerance and/or accumulation of PTE in alfalfa plants as follows: (i) selection of PTE tolerant cultivars, (ii) applying plant growth regulators, (iii) addition of chelating agents, fertilizer, and biochar materials, and (iv) inoculation of soil microbes. Finally, we indicate that the selection of PTE-tolerant cultivars along with inoculation of soil microbes may be an efficient and eco-friendly strategy of the soil PTE phytoremediation.

A critical review of microplastics in the soil-plant system: Distribution, uptake, phytotoxicity and prevention

Microplastics (MPs) are creating an emerging threat on the soil ecosystems and are of great global concern. However, the distribution in soil-plant system, as well as the phytotoxicity and impact mechanisms of MPs remain largely unexplored so far. This study introduced the diverse sources of MPs and showed the significant spatial variation in the global geographic distribution of MPs contamination based on data collected from 116 studies (1003 sampling sites). We systematically discussed MPs phytotoxicity, such as plant uptake and migration to stems and leaves, delaying seed germination, impeding plant growth, inhibiting photosynthesis, interfering with nutrient metabolism, causing oxidative damage, and producing genotoxicity. We further highlighted the alterations of soil structure and function by MPs, as well as their self and load toxicity, as potential mechanisms that threaten plants. Finally, this paper provided several preventive strategies to mitigate soil MPs pollution and presented research gaps in the biogeochemical behavior of MPs in soil-plant systems. Meanwhile, we recommended that methods for the quantitative detection of MPs accumulated in plant tissues should be explored and established as soon as possible. This review will improve the understanding of the environmental behavior of MPs in soil-plant systems and provide a theoretical reference to better assess the ecological risk of MPs.

Rhizobium Inoculation Enhances the Resistance of Alfalfa and Microbial Characteristics in Copper-Contaminated Soil

Some studies have reported the importance of rhizobium in mitigating heavy metal toxicity, however, the regulatory mechanism of the alfalfa-rhizobium symbiosis to resist copper (Cu) stress in the plant-soil system through biochemical reactions is still unclear. This study assessed the effects of rhizobium (Sinorhizobium meliloti CCNWSX0020) inoculation on the growth of alfalfa and soil microbial characteristics under Cu-stress. Further, we determined the regulatory mechanism of rhizobium inoculation to alleviate Cu-stress in alfalfa through plant-soil system. The results showed that rhizobium inoculation markedly alleviated Cu-induced growth inhibition in alfalfa by increasing the chlorophyll content, height, and biomass, in addition to nitrogen and phosphorus contents. Furthermore, rhizobium application alleviated Cu-induced phytotoxicity by increasing the antioxidant enzyme activities and soluble protein content in tissues, and inhibiting the lipid peroxidation levels (i.e., malondialdehyde content). In addition, rhizobium inoculation improved soil nutrient cycling, which increased soil enzyme activities (i.e., β-glucosidase activity and alkaline phosphatase) and microbial biomass nitrogen. Both Pearson correlation coefficient analysis and partial least squares path modeling (PLS-PM) identified that the interactions between soil nutrient content, enzyme activity, microbial biomass, plant antioxidant enzymes, and oxidative damage could jointly regulate plant growth. This study provides comprehensive insights into the mechanism of action of the legume-rhizobium symbiotic system to mitigate Cu stress and provide an efficient strategy for phytoremediation of Cu-contaminated soils.

[Clinical features of young inpatients with angle-closure glaucoma]

Objective: To analyze the composition of diagnosis in young inpatients with angle-closure glaucoma and to compare the clinical characteristics between primary angle-closure glaucoma (PACG) and secondary angle-closure glaucoma (SACG). Methods: This was a retrospective case series study. Angle-closure glaucoma patients aged 40 years or younger and hospitalized in Zhongshan Ophthalmic Center from January 2012 to December 2019 were included. The clinical diagnosis, gender, onset age, and results of general ophthalmic examination, A-scan ultrasonography measurements, ultrasound biomicroscopy, optical coherence tomography and visual field were recorded. The proportions and composition of PACG and SACG, as well as the misdiagnosis ratio, were analyzed. The onset age, visual acuity, visual field, and ocular parameters were compared between patients with PACG and SACG. Non-normally distributed data were represented by M (Q₁, Q₃). The difference between groups were compared by Mann-Whitney U test, Chi square test, and independent sample t test. Results: A total of 243 patients (243 eyes) were included in this study. The mean onset age was (28±9) years, and the male-to-female ratio was 1∶1.79. There were 93 patients (38.3%) in PACG group and 150 (61.7%) in SACG group. The age of PACG [34(28, 38)] was older than that of SACG [28(19, 34)], and the proportion of males in the SACG group (44.0%, 66/150) was significantly higher than that in the PACG group (22.6%, 21/93) (Z=-5.34, χ²=11.46; both P<0.01). Nanophthalmos (22.7%, 34 cases), autosomal recessive bestrophinopathy (ARB) (19.3%, 29 cases), uveitis (18.7%, 28 cases) and retinitis pigmentosa (14.0%, 21 cases) were the most common causes of SACG. The best corrected visual acuity (logarithm of the minimum angle of resolution) was 0.10 (0.00, 0.48) and 0.40 (0.06, 1.00), mean deviation of visual field was -8.07 (-27.49, -2.09) and -15.04 (-28.75, -5.97) dB, and subfoveal choroidal thickness was (452.3±130.7) and (396.3±120.9) μm in the PACG and SACG groups, respectively. The differences were statistically significant (Z=-4.86, -2.14; t=2.37; all P<0.05). There was no statistical difference in intraocular pressure, cup-to-disc ratio, extent of peripheral anterior synechia, central anterior chamber depth, lens thickness, mean retinal nerve fiber layer thickness between these two groups (all P>0.05). The misdiagnosis ratio was 10.7% (26/243) in all patients, while the misdiagnosis ratio of the SACG group (16.7%, 25/150) was higher than that of the PACG group (1.1%, 1/93) (χ²=14.61, P<0.001). Conclusions: PACG, nanophthalmos and ARB are the most common etiologies in young inpatients with angle-closure glaucoma. Compared to PACG, patients with SACG are younger, with worse visual acuity and more severe visual field defects, and easier to be misdiagnosed.

Reduction of Cu and nitrate leaching risk associated with EDDS-enhanced phytoextraction process by exogenous inoculation of plant growth promoting rhizobacteria

Biodegradable chelant (S,S)-N,N'-ethylenediaminedisuccinic acid (EDDS) has the more advantages of enhanced metal mobility, rapid degradation, environmental friendliness, and ammonium release. However, the risk of metal and/or nitrate residues and leaching within EDDS biodegradation remains as the bottleneck for the widespread application of EDDS-induced phytoremediation. This study aims to explore if the inoculation of plant growth-promoting rhizobacteria (PGPRs) can eliminate the risk associated with the short-term application of EDDS by investigating Cu phytoextraction and soil nitrate content. Results showed that EDDS application significantly increased the copper (Cu) concentration in shoots, soil total Cu, NH₄⁺-N and NO₃^--N content, but decreased plant biomass. The inoculation of PGPRs in the soil showed a strong ability to increase plant biomass, Cu phytoextraction and soil NH₄⁺-N content, and decrease soil Cu and NO₃^--N content. Moreover, bacterial dominant taxa were found to be the largest contributors to soil NH₄⁺-N and NO₃^--N variation, and the abundance of denitrifying bacteria (Bacteroidetes and Stenotrophomonas) decreased in the treatment with PGPRs. The risk of residual Cu and nitrate leaching was reduced by the inoculation of PGPRs without significantly changing the stability of the bacterial community. These new findings indicate that the exogenous application of beneficial rhizobacteria can provide an effective strategy to reduce the risk in metal-contaminated soils of chelant-assisted phytoextraction.