Land use modified impacts of global change factors on soil microbial structure and function: A global hierarchical meta-analysis.

Nitrogen cycling in terrestrial ecosystems is critical for biodiversity, vegetation productivity and biogeochemical cycling. However, little is known about the response of functional nitrogen cycle genes to global change factors in soils under different land uses. Here, we conducted a multiple hierarchical mixed effects meta-analyses of global change factors (GCFs) including warming (W+), mean altered precipitation (MAP+/-), elevated carbon dioxide concentrations (eCO2), and nitrogen addition (N+), using 2706 observations extracted from 200 peer-reviewed publications. The results showed that GCFs had significant and different effects on soil microbial communities under different types of land use. Under different land use types, such as Wetland, Tundra, Grassland, Forest, Desert and Agriculture, the richness and diversity of soil microbial communities will change accordingly due to differences in vegetation cover, soil management practices and environmental conditions. Notably, soil bacterial diversity is positively correlated with richness, but soil fungal diversity is negatively correlated with richness, when differences are driven by GCFs. For functional genes involved in nitrification, eCO2 in agricultural soils and the interaction of N+ with other GCFs in grassland soils stimulate an increase in the abundance of the AOA-amoA gene. In agricultural soil, MAP+ increases the abundance of nifH. W+ in agricultural soils and N+ in grassland soils decreased the abundance of nifH. The abundance of the genes nirS and nirK, involved in denitrification, was mainly negatively affected by W+ and positively affected by eCO2 in agricultural soil, but negatively affected by N+ in grassland soil. This meta-analysis was important for subsequent research related to global climate change. Considering data limitations, it is recommended to conduct multiple long-term integrated observational experiments to establish a scientific basis for addressing global changes in this context.

Relationship between arginine methylation and vascular calcification.

In patients on maintenance hemodialysis (MHD), vascular calcification (VC) is an independent predictor of cardiovascular disease (CVD), which is the primary cause of death in chronic kidney disease (CKD). The main component of VC in CKD is the vascular smooth muscle cells (VSMCs). VC is an ordered, dynamic activity. Under the stresses of oxidative stress and calcium-­phosphorus imbalance, VSMCs undergo osteogenic phenotypic transdifferentiation, which promotes the formation of VC. In addition to traditional epigenetics like RNA and DNA control, post-translational modifications have been discovered to be involved in the regulation of VC in recent years. It has been reported that the process of osteoblast differentiation is impacted by catalytic histone or non-histone arginine methylation. Its function in the osteogenic process is comparable to that of VC. Thus, we propose that arginine methylation regulates VC via many signaling pathways, including as NF-B, WNT, AKT/PI3K, TGF-/BMP/SMAD, and IL-6/STAT3. It might also regulate the VC-related calcification regulatory factors, oxidative stress, and endoplasmic reticulum stress. Consequently, we propose that arginine methylation regulates the calcification of the arteries and outline the regulatory mechanisms involved.

Influence of the Injection Bias on the Capacitive Sensing of the Test Mass Motion of Satellite Gravity Gradiometers.

The performance of the capacitive gap-sensing system plays a critical role in a satellite-based gravity gradiometer that is developed using an electrostatic accelerometer. The capacitive sensing gain mainly depends on the stabilized injection bias amplitude, the gain of the transformer bridge, and the trans-impedance amplifier. Previous studies have indicated that amplitude noise is the main factor influencing the noise of capacitive displacement detection. Analyzing the capacitive gap-sensing system indicates that the amplitude, frequency, phase, and broadband noises of the stabilized injection bias have varying levels of influence on the performance of the detection system. This paper establishes a model to clarify the mentioned effects. The validation of the sub-tests demonstrates that the analysis and evaluation results of various noise coefficients are highly consistent with the model's predicted outcomes.

HDAC2 counteracts vascular calcification by activating autophagy in chronic kidney disease.

Vascular calcification is a major risk factor for cardiovascular disease mortality, with a significant prevalence in chronic kidney disease (CKD). Pharmacological inhibition of histone acetyltransferase has been proven to protect against from vascular calcification. However, the role of Histone Deacetylase 2 (HDAC2) and molecular mechanisms in vascular calcification of CKD remains unknown. An in vivo model of CKD was established using mouse fed with a high adenine and phosphate diet, and an in vitro model was produced using human aortic vascular smooth muscle cells (VSMCs) stimulated with ß-glycerophosphate (ß-GP). HDAC2 expression was found to be reduced in medial artery of CKD mice and ß-GP-induced VSMCs. Overexpression of HDAC2 attenuated OPN and OCN upregulation, α-SMA and SM22α downregulation, and calcium deposition in aortas of CKD. The in vitro results also demonstrated that ß-GP-induced osteogenic differentiation was inhibited by HDAC2. Furthermore, we found that HDAC2 overexpression caused an increase in LC3II/I, a decrease in p62, and an induction of autophagic flux. Inhibition of autophagy using its specific inhibitor 3-MA blocked HDAC2's protective effect on osteogenic differentiation in ß-GP-treated VSMCs. Taken together, these results suggest that HDAC2 may protect against vascular calcification by the activation of autophagy, laying out a novel insight for the molecular mechanism in vascular calcification of CKD.

UV-Induced Synthesis of Hybrid HMDSO/SiO2 Thin Films with Compositional Gradients for High-Performance Atomic Oxygen Resistance.

A flexible, dense, defect-free, highly adhesive, and highly dissociation energy-rich protective coating is essential to enhance the atomic oxygen (AO) resistance of polymeric materials in a low Earth orbit (LEO). In this work, a dense, defect-free hybrid HMDSO/SiO2 thin film coating with compositional gradients on the surface of polyimide was synthesized using vacuum-ultraviolet (VUV) irradiation. The effects of VUV irradiation on the morphology, optical transmittance, and chemical components of plasma-polymerized HMDSO (pp-HMDSO) thin-film coatings deposited on the polyimide surface were investigated in depth. There were no defects such as cracks and holes in the surface morphology of pp-HMDSO films after VUV irradiation, but the surface roughness increased slightly, and the corresponding optical transmittance decreased slightly. The chemical components of pp-HMDSO films were changed in the depth direction starting from the top of the surface, forming hybrid HMDSO/SiO2 thin films with compositional gradients. The component gradient HMDSO/SiO2 composite coating further enhanced the atomic oxygen resistance of the polyimide due to the surface layer of the UV-modified coating enriched with high dissociation energy SiOx material. Therefore, this work provides a facile UV-induced synthesis method to prepare dense, defect-free, and highly dissociation energy-rich protective gradient coatings, which are promising not only for excellent AO protection in LEO but also for potential application in water-oxygen barrier films.

Hydrothermal carbonization of biogas slurry and cattle manure into soil conditioner mitigates ammonia volatilization from paddy soil.

Hydrothermal carbonization of biogas slurry and animal manure into hydrochar could enhance waste recycling waste and minimize ammonia (NH3) volatilization from paddy fields. In this study, cattle manure-derived hydrochar prepared in the presence of Milli-Q water (CMWH) and biogas slurry (CMBSH), and biogas slurry-based hydrochar embedded with zeolite (ZHC) were applied to rice-paddy soil. The results demonstrated that CMBSH and ZHC treatments could significantly mitigate the cumulative NH3 volatilization and yield-scale NH3 volatilization by 27.9-45.2% and 28.5-45.4%, respectively, compared to the control group (without hydrochar addition), and significantly correlated with pH and ammonium-nitrogen (NH4+-N) concentration in floodwater. Nitrogen (N) loss via NH3 volatilization in the control group accounted for 24.9% of the applied N fertilizer, whereas CMBSH- and ZHC-amended treatments accounted for 13.6-17.9% of N in applied fertilizer. The reduced N loss improved soil N retention and availability for rice; consequently, grain N content significantly increased by 6.5-14.9% and N-use efficiency increased by 6.4-16.0% (P < 0.05), respectively. Based on linear fitting results, NH3 volatilization mitigation resulted from lower pH and NH4+-N concentration in floodwater that resulted from the acidic property and specific surface area of hydrochar treatments. Moreover, NH3-oxidizing archaea abundance in hydrochar-treated soil decreased by 40.9-46.9% in response to CMBSH and ZHC treatments, potentially suppressing NH4+-N transformation into nitrate and improving soil NH4+-N retention capacity. To date, this study applied biogas slurry-based hydrochar into paddy soil for the first time and demonstrated that ZHC significantly mitigated NH3 and increased N content. Overall, this study proposes an environmental-friendly strategy to recycle the wastes, biogas slurry, to the paddy fields to mitigate NH3 volatilization and increase grain yield of rice.

Removing DOM from chloride modified hydrochar could improve Cu2+ adsorption capacity from aqueous solution.

The behavior and composition of hydrochar-based dissolved organic matter (DOM) would affect the efficiency of copper (Cu) removal from wastewater through adsorption. In this study, the reed was hydrolyzed in the presence of feedwater with and without ZnCl2, FeCl3, and SnCl4 to produce pristine hydrochars (PHCs), which were named H2O-HC, ZnCl2-HC, FeCl3-HC, and SnCl4-HC. After removal of DOM, washed hydrochars (WHCs) were obtained, labelled as W-H2O-HC, W-ZnCl2-HC, W-FeCl3-HC, and W-SnCl4-HC. The release dynamics of DOM from PHCs were analyzed, and the adsorption behaviors of Cu2+ on both PHCs and WHCs were investigated. The results showed that chloride-modifications were beneficial for the porosity, specific surface area (SSA), and functional groups of WHCs. Meanwhile, the quantity of hydrochar-based DOM was significantly affected by chloride-modifications. In particular, the relative contents of Ar-P and Fa-L in the DOM released from hydrochars varied with time and modification. Furthermore, the Qe of Cu2+ adsorption on WHCs followed the order of W-SnCl4-HC > W-FeCl3-HC > W-ZnCl2-HC > W-H2O-HC at 15 °C. Compared to PHCs, the adsorption capacity of Cu2+ on WHCs was improved by 7.15-119.77% at the temperature of 35 °C. Simultaneously, the adsorption capacity of Cu2+ in WHCs showed a significant correlation with the SSA via physical adsorption (P < 0.05). Moreover, XPS analysis revealed that Cu2+ adsorption also occurred via complexation and chelation through newly formed Cu-O group between W-SnCl4-HC and Cu2+. Notably, the increase of Cu2+ adsorption in WHCs was significantly correlated with the release of Fa-L and Ar-P from PHCs (P < 0.05). This study found that the content and composition of hydrochar-based DOM could be a major driving factor for Cu2+ adsorption.

Impacts of atmospheric copper and cadmium deposition on the metal accumulation of camphor leaves and rings around a large smelter.

The atmospheric deposition of copper (Cu) and cadmium (Cd) was monitored in eight sites around a Cu smelter with similar distance to verify whether tree leaf and ring can be used as bio-indicators to track spatial pollution record. Results showed that total atmospheric deposition of Cu (103-1215 mg/m2/year) and Cd (3.57-11.2 mg/m2/year) were 4.73-66.6 and 3.15-12.2 times higher than those in background site (164 mg/m2/year and 0.93 mg/m2/year). The frequencies of wind directions significantly influenced the atmospheric deposition of Cu and Cd, and the highest atmospheric deposition of Cu and Cd were at the prevalent northeastern wind (JN), and low frequency south (WJ) and north (SW) winds for the lowest deposition fluxes. Since the bioavailability of Cd was higher than that of Cu, the atmospheric deposition of Cd was more easily adsorbed by tree leaf and ring, resulting in only significant relation between atmospheric Cd deposition and Cinnamomum camphora leaves and tree ring Cd. Although tree rings cannot correctly record the atmospheric Cu and Cd deposition, higher concentrations in the indigenous tree rings than the transplanted tree rings suggested that tree rings can reflect to some extent the variations of atmospheric deposition. Generally, spatial pollution of atmospheric deposition of heavy metals cannot reflect the distribution of soil total and available metals around the smelter, and only camphor leaf and tree ring can bio-indicate Cd deposition. A major implication of these findings is that leaf and tree ring can serve for biomonitoring purposes to assess the spatial distribution of atmospheric deposition metal with high bioavailability around a pollution source with similar distance.

Substituting urea with biogas slurry and hydrothermal carbonization aqueous product could decrease NH3 volatilization and increase soil DOM in wheat growth cycle.

Biogas slurry (BS) and hydrothermal carbonization aqueous products (HAP), which are rich in nitrogen (N) and dissolved organic matter (DOM), can be used as organic fertilizer to substitute inorganic N fertilizer. To evaluate the effects of co-application of BS and HAP on the ammonia (NH3) volatilization and soil DOM content in wheat growth season, we compared six treatments that substituting 50%, 75%, and 100% of urea-N with BS plus HAP at low (L) or high (H) ratio, named BCL50, BCL75, BCL100, BCH50, BCH75, BCH100, respectively. Meanwhile, urea alone treatment was set as the control (CKU). The results showed that both BCL and BCH treatments significantly mitigate the NH3 volatilizations by 9.1%-45.6% in comparison with CKU (P < 0.05), whose effects were correlated with soil NH4+-N content. In addition, the decrease in soil urease activity contributed to the lower NH3 volatilization following application of BS plus HAP. Notably, BS plus HAP applications increased the microbial byproduct- and humic acid-like substances in soil by 9.9%-74.5% and 100.7%-451.9%, respectively. Consequently, BS and HAP amended treatments significantly increased soil humification index and DOM content by 13.7%-41.2% and 38.4%-158.7%, respectively (P < 0.05). This study suggested that BS and HAP could be co-applied into agricultural soil as a potential alternative of inorganic fertilizer N, which can decrease NH3 loss but increase soil fertility.

[Twenty years in the 21st century: identification technologies for and multimodal research on chemical changes in exploration of processing mechanism of Chinese medicine].

Chinese medicine undergoes complex chemical changes during processing and identifying these changes is the key to the processing mechanism. In the past 20 years of the 21 st century, research on the chemical changes in Chinese medicine after processing has focused the changes in the biopharmaceutical process in addition to the variation during processing. With the surging of information technologies, various identification technologies(instrumental analysis techniques, molecular biological techniques, data mining techniques, and biotransformation techniques) have developed rapidly and been widely applied to the research on processing mechanism. Thus, based on the chemical changes in the processing and biopharmaceutical process, the author suggested a research tactic of multimodal identification as the core by reorganizing key technologies for chemical identification from studies of the processing mechanism of Chinese me-dicine, aiming at establishing an interdisciplinary multi-dimensional research model for the processing mechanism of Chinese medicine.

[Twenty years in the 21st century: research approaches and techniques in modern system biology for mechanisms of Chinese medicinal processing].

Clarifying the mechanisms of Chinese medicinal processing is pivotal to the modernization of Chinese medicine. Research on Chinese medicinal processing gives priority to the mechanisms of the processing in enhancing efficacy, reducing toxicity, and repurposing medicinals. During the past 20 years, scholars have carried out in-depth studies on the mechanisms of Chinese medicinal processing via modern system biology. They mainly focused on the changes of medicinal properties and efficacy caused by processing using techniques of modern pharmacology and molecular biology, spectrum-efficacy correlation, and biophoton emission. However, these techniques fail to reflect the holistic view of traditional Chinese medicine. With the introduction of system biology, multi-omics techno-logies(genomics, transcriptomics, proteomics, and metabolomics) have surged, which have been applied to the research on the mec-hanisms of Chinese medicinal processing. These multi-omics technologies have advantages in the research on holism. This study aims to summarize the research techniques and approaches in system biology for mechanisms of Chinese medicinal processing in the past 20 years and analyze the limitations and advantages of them. It is concluded that the multi-omics techniques of system biology can reconstruct the mechanisms of Chinese medicinal processing. This study provides a new direction for further research on the mechanisms of Chinese medicinal processing.

Influence of polyethylene terephthalate microplastic and biochar co-existence on paddy soil bacterial community structure and greenhouse gas emission.

Microplastic (MP) contamination is ubiquitous in agricultural soils. As a cost-effective soil amendment, biochar (BC) often coincides with MP exposure. However, little research has been conducted regarding the independent and combined effects of MPs and BC on the soil microbiome and N2O/CH4 emissions. Therefore, in this study, polyethylene terephthalate (PET) and wheat straw-derived BC were used, respectively, as representative MP and BC during an entire rice growth period. The high-throughput sequencing results showed that PET alone lowered bacterial diversity by 26.7%, while PET and BC co-existence did not induce apparent change. The relative abundances of some microbes (e.g., Cyanobacteria, Verrucomicrobia, and Bacteroidetes) that are associated with C and N cycling were changed at the phylum and class levels by all the treatments. In comparison with the control, the treatment of BC, PET, and their co-existence reduced the cumulative CH4 emissions by 50%, 53%, and 61%, respectively. The higher mitigation by BC + PET may be the result of higher soil Eh and a consequently lower methanogenesis functional gene mcrA abundance in the treated soils. In addition, BC and PET alone, as well as their combined treatment, increased the abundance of nitrification genes, enhancing the soil nitrification process. However, the relative contribution of the nitrification process to N2O emission was possibly lower than that of denitrification, in which the N2O reductase gene nosZ was found to be the primary gene regulating N2O emissions. BC alone increased nosZ abundance by 42.3%, thereby showing the potential in suppressing N2O emission. In contrast, when BC was co-added with PET, the nosZ abundance lowered possibly because of increased soil aeration, and thus its cumulative N2O emission was 38% higher than the BC treatment. Overall, these results demonstrated that BC and PET function differently in soil ecosystems when they coexisted.

Presence of microplastics alone and co-existence with hydrochar unexpectedly mitigate ammonia volatilization from rice paddy soil and affect structure of soil microbiome.

Microplastics (MPs), as an emerging pollutant, may cause deleterious changes to the nitrogen cycle in terrestrial ecosystems. However, single impact of MPs and synergistic effects of MPs with hydrochar on ammonia (NH3) volatilization and soil microbiome in paddy fields has been largely unexplored. In this study, polyethylene (PE), polyacrylonitrile (PAN) and straw-derived hydrochar (HBC) were selected for observations in an entire rice cycle growth period. Results showed that under the condition of 0.5% (w/w) MPs concentration, presence of MPs alone and co-existence of MPs and HBC (MPs + HBC) unexpectedly mitigated cumulative NH3 volatilization from paddy soil compared with the control with no MPs or HBC addition. MPs + HBC increased NH3 volatilization by 37.8-46.2% compared with MPs alone, indicating that co-existence of MPs and HBC weaken the mitigation effect of MPs on NH3 volatilization. Additionally, results of nitrogen cycle related microorganisms closely related to NH3 volatilization demonstrated that MPs + HBC altered the bacterial community structure and species diversity. These findings provide an important opportunity to advance our understanding of the impacts of MPs in agricultural environment and soils, and provide a sound theoretical basis for rationalizing the application of HBC in soil with MPs.

Design and Performance Verification of a Space Radiation Detection Sensor Based on Graphene.

In order to verify the performance of a graphene-based space radiation detection sensor, the radiation detection principle based on two-dimensional graphene material was analyzed according to the band structure and electric field effect of graphene. The method of space radiation detection based on graphene was studied and then a new type of space radiation sensor samples with small volume, high resolution, and radiation-resistance was formed. Using protons and electrons, the electrical performance of GFET radiation sensor was verified. The designed graphene space radiation detection sensor is expected to be applied in the radiation environment monitoring of the space station and the moon, and can also achieve technological breakthroughs in pulsar navigation and other fields.

[Gaseous Nitrogen Emission from Soil After Application of NH4+-N Loaded Biochar].

To safely and effectively transfer NH4+-N from eutrophic water to soil, biochar was applied to adsorb NH4+-N from wastewater, and this NH4+-N loaded biochar (N-BC) was subsequently used as a soil amendment. Understanding the influence of N-BC on N2O-N emission and NH3-N volatilization is important for both decreasing the application of chemical fertilizers and reducing gaseous nitrogen loss from soil. In this study, experiments were conducted in soil columns with four treatments, namely CK (no fertilizer), NPK (chemical fertilizer), N-BC+PK (NH4+-N loaded biochar+chemical fertilizer), and BC+NPK (biochar+chemical fertilizer). Compared to both the NPK and BC+NPK treatments, N-BC+PK significantly reduced the cumulative N2O-N emissions and NH3-N volatilization, as well as the total gaseous nitrogen loss from the soil (P<0.05). Relative to NPK and BC+NPK, cumulative N2O-N emissions decreased by 33.62% and 24.64%, cumulative NH3-N volatilization decreased 70.64% and 79.29%, and the cumulative total gaseous nitrogen loss decreased by 64.97% and 73.75%. In particular, BC+NPK significantly enhanced the cumulative NH3-N volatilization. Furthermore, the N2O-N emission flux and NH3-N volatilization rate were significantly positively correlated with the NH4+-N concentration, NO3--N concentration, and pH of soil (P<0.01). Overall, using NH4+-N loaded biochar can significantly decrease N2O-N emissions and NH3-N volatilization, relative to the traditional application combining biochar and chemical fertilizer. This research provides solid theoretical support and data for the application of NH4+-N loaded biochar in soil, to reduce gaseous nitrogen loss.

Chemical aging of hydrochar improves the Cd2+ adsorption capacity from aqueous solution.

Hydrochar (HC) serves as a promising adsorbent to remove the cadmium from aqueous solution due to porous structure. The chemical aging method is an efficient and easy-operated approach to improve the adsorption capacity of HC. In this study, four chemical aging hydrochars (CAHCs) were obtained by using nitric acid (HNO3) with mass fractions of 5% (N5-HC), 10% (N10-HC), and 15% (N15-HC) to age the pristine HC (N0-HC) and remove the Cd2+ from the aqueous solution. The results displayed that the N15-HC adsorption capacity was 19.99 mg g-1 (initial Cd2+ concentration was 50 mg L-1), which increased by 7.4 folds compared to N0-HC. After chemical aging, the specific surface area and oxygen-containing functional groups of CAHCs were increased, which contributed to combination with Cd2+ by physical adsorption and surface complexation. Moreover, ion exchange also occurred during the adsorption process of Cd2+. These findings have important implications for wastewater treatment to transform the forestry waste into a valuable adsorbent for Cd2+ removal from water.

Biowaste hydrothermal carbonization aqueous product application in rice paddy: Focus on rice growth and ammonia volatilization.

Hydrothermal carbonization (HTC) is known as a green biomass conversion technology. However, it often suffers from the issue of disposing hydrothermal carbonization aqueous products (HCAP). Based on the characterization and composition of acidic HCAP, a rice paddy soil column experiment was conducted to observe the effects of HCAP on ammonia (NH3) volatilization form paddy soil and rice yield. The experiment was designed with five treatments. HCAPs were produced at 220 °C and (SHC220-L) and 260 °C (SHC260-L) derived from poplar sawdust, HCAP produced at 220 °C (WHC220-L) and 260 °C (WHC260-L) derived from wheat straw, and a control group without HCAP application (termed CKU hereafter). The results showed that HCAP treatments increased the rice yield by 4.30%-26.0% compared to CKU. HACPs prepared at lower temperatures (SHC220-L and WHC220-L) mitigated the cumulative NH3 volatilization by 11.2% and 7.6%, respectively, and mitigated yield-scale NH3 volatilization (cumulative NH3 volatilization/total yield) by 14.2% âˆ¼ 22.4%. HCAP significantly improved the N use efficiency of rice. We found that the NH3 volatilization was related to NH4+-N concentration and pH of surface water, soil TOC and NH4+-N oxidation functional genes. This study implied that HCAP could be potentially used as a liquid fertilizer, which will be a potential substitute for chemical N fertilizers. There is still a long way before HCAP can be applied in full-scale for N fertilizer reduction and waste recycle.

A Cylindrical Triode Ultrahigh Vacuum Ionization Gauge with a Carbon Nanotube Cathode.

In this study, a cylindrical triode ultrahigh vacuum ionization gauge with a screen-printed carbon nanotube (CNT) electron source was developed, and its metrological performance in different gases was systematically investigated using an ultrahigh vacuum system. The resulting ionization gauge with a CNT cathode responded linearly to nitrogen, argon, and air pressures in the range from ~4.0 ± 1.0 × 10-7 to 6 × 10-4 Pa, which is the first reported CNT emitter-based ionization gauge whose lower limit of pressure measurement is lower than its hot cathode counterpart. In addition, the sensitivities of this novel gauge were ~0.05 Pa-1 for nitrogen, ~0.06 Pa-1 for argon, and ~0.04 Pa-1 for air, respectively. The trend of sensitivity with anode voltage, obtained by the experimental method, was roughly consistent with that gained through theoretical simulation. The advantages of the present sensor (including low power consumption for electron emissions, invisible to infrared light radiation and thermal radiation, high stability, etc.) mean that it has potential applications in space exploration.

Nitric acid-modified hydrochar enhance Cd2+ sorption capacity and reduce the Cd2+ accumulation in rice.

Remediating the agricultural soil polluted by cadmium (Cd) is a serious issue in China. Hydrochar showed its potential to purify Cd-contaminated water and improve Cd-contaminated soil due to its vast amounts of macro- and microporous structures. In this study, three concentration gradients of nitric acid (HNO3, mass fraction: 5%, 10%, 15%) were implemented to age pristine wheat straw hydrochar (N0-HC) aiming to improve surface physiochemical properties. Four HNO3-aging hydrochars named N0-HC, N5-HC, N10-HC, N15-HC were used to both remove Cd2+ from aqueous solution and improve soil properties. Results showed that HNO3-aging significantly improved the Cd2+ adsorption capacity by 1.9-9.9 folds compared to crude hydrochar due to the increased specific surface area (by 1.5-6.5 folds) and oxygen-containing functional group abundance (by 4.5-22.1%). Besides, initial solution pH of 8 or environmental temperature of 318.15 K performed the best Cd2+ adsorption capacity. Furthermore, the process of Cd2+ adsorption was fitted best to pseudo-second-order (R2 = 0.95) and Langmuir models (R2 = 0.98), respectively. Nanjing 46 (Oryza sativa L) and HNO3-aging hydrochars were furtherly applied into Cd-contaminated paddy soil to investigate the mitigation of Cd translation from soil to rice. N15-HC-1% (w/w) performed the best effect on reducing cadmium accumulation in various parts of rice plants. Overall, this research provided an approach to improve hydrochar capacity to remove Cd2+ from aqueous solution and mitigate Cd translation from soil to rice.

Co-application of biogas slurry and hydrothermal carbonization aqueous phase substitutes urea as the nitrogen fertilizer and mitigates ammonia volatilization from paddy soil.

Biogas slurry (BS) and bio-waste hydrothermal carbonization aqueous phase (HP) are nutrient-rich wastewater. To prevent environment contamination, transforming BS and HP into synthetic fertilizers in the agricultural field can potentially realize resource utilization. We hypothesized that acidic HP could neutralize alkaline BS, adjusting floodwater pH from 6.88 to 8.00 and mitigating ammonia (NH3) volatilization from the paddy soil. In this soil column study, the mixture of BS and HP was applied to paddy soil to substitute 50%, 75%, and 100% to urea. With a low (L) or high (H) ratio of HP, treatments were labeled as BCL50, BCL75, BCL100, BCH50, BCH75, and BCH100. Results showed that microbial byproduct- and fulvic acid-like substance were the main components in BS and HP using 3D-EEM analysis, respectively. Co-application of BS and HP mitigated the NH3 volatilization by 4.2%-65.5% compared with CKU. BCL100 and BCH100 treatments significantly (P < 0.05) mitigated NH3 volatilization by 65.5% and 56.8%, which also significantly (P < 0.05) mitigated the yield-scale NH3 volatilization by 49.6% and 42.3%, compared with CKU. The low NH4+-N concentration and pH value in floodwater were the main reason explained the NH3 mitigation. Therefore, this study demonstrated that BS and HP co-application can substitute the urea as a valuable N fertilizer in a rational rate and meanwhile mitigate the NH3 volatilization. This study will provide new ideas for the utilization of BS and HP resources in the context of ammonia mitigation.