Land application of biomass-derived biochar has been increasingly recommended as a beneficial soil amendment for nutrients (such as N, P) retention. However, the small-scale biochar particles, ...especially those in the nano-scale range, may carry nutrients downward the soil profile, reducing nutrition retention and posing a potential risk to the groundwater. In this study, column experiments were conducted to investigate the retention and transport of phosphorus (P) in two acidic and two alkaline soils as affected by wood chip-derived biochar nanoparticles (NPs). In acidic paddy and red soils, biochar NPs facilitated the retention of P, increasing by about 24% and 16%, respectively, compared to the biochar absence. It is because biochar NPs stabilize soil Fe/Al oxides and dissolved organic carbon (DOC), thereby reducing the release of Fe/Al oxides- and DOC-associated P. In contrast, in alkaline huangmian and chao soils, retention of P was reduced in the presence of biochar NPs, decreasing by about 23% and 18%, respectively. It was mainly due to the increased transport of Fe/Al oxides-associated P in effluents. Moreover, biochar NPs could also act as a P carrier, mediating the retention of P. The diffusive gradients in thin films provided in-suit measurement of labile P in soil profiles, showing much lower labile P from retained P in acidic soils than that from alkaline soils though the labile P with biochar NPs presence was increased in all soils. Our findings indicate that biochar NPs have contrasting effects on the retention of P in acidic and alkaline soils, implying the cautious land applications of biochar for nutrients retention in soils with different acidities.
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•Biochar NPs facilitated the retention of P in acidic soils.•Biochar NPs reduced the retention of P in alkaline soils.•Biochar NPs could act as a carrier for phosphorus migration in both acidic and alkaline soils.•Labile P with biochar NPs presence was increased in all soils.•Labile P from P-retained acidic soils was much lower than that from alkaline soils.
Biochar nanoparticles have contrasting effects on the retention of phosphorus in acidic and alkaline soils.
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•ACF can efficiently activate peroxymonosulfate to degrade organic pollutants.•Basic functional groups may mainly increase the adsorption capacity of ACF.•C1, N1, N2 have promoting ...effect on the ACF catalyzed PMS oxidation.•Modification by heat after nitric acid is also a way of ACF regeneration.
A commercial activated carbon fiber (ACF-0) was modified by three different methods: nitration treatment (ACF-N), heat treatment (ACF-H) and heat treatment after nitration (ACF-NH), and the effects of textural and chemical properties on the ability of the metal-free ACF-catalyzed peroxymonosulfate (PMS) oxidation of Reactive Black 5 (RB5), an azo dye being difficultly adsorbed onto ACF, in aqueous solution were investigated in this work. Surface density of functional groups, surface area changes, surface morphology and the chemical state inside ACF samples were characterized by Boehm titration, N2 adsorption, scanning electron microscopy in couple with energy dispersive spectroscopy (SEM-EDS) and X-ray photoelectron spectroscopy (XPS), respectively. XPS spectra deconvolution was applied to figure out the importance of surface nitrogen-containing function groups. We found that π-π, pyridine and amine have promoting effect on the catalytic oxidation while the −NO2 has inhibitory effect on the ACF/PMS systems for RB5 destroy. Sustainability and renewability of the typical ACF-NH for catalytic oxidation of RB5 were also discussed in detail. Information about our conclusions are useful to control and improve the performance of ACF-catalyzed PMS oxidation for organic pollutants in wastewater treatment.
Plastic pollution is a global concern given its prevalence in aquatic and terrestrial ecosystems. Studies have been conducted on the distribution and impact of plastic pollution in marine ecosystems, ...but little is known on terrestrial ecosystems. Plastic mulch has been widely used to increase crop yields worldwide, yet the impact of plastic residues in cropland soils to soil health and crop production in the long term remained unclear. In this paper, using a global meta‐analysis, we found that the use of plastic mulch can indeed increase crop yields on average by 25%–42% in the immediate season due to the increase of soil temperature (+8%) and moisture (+17%). However, the unabated accumulation of film residues in the field negatively impacts its physicochemical properties linked to healthy soil and threatens food production in the long term. It has multiple negative impacts on plant growth including crop yield (at the mean rate of −3% for every additional 100 kg/ha of film residue), plant height (−2%) and root weight (−5%), and soil properties including soil water evaporation capacity (−2%), soil water infiltration rate (−8%), soil organic matter (−0.8%) and soil available phosphorus (−5%) based on meta‐regression. Using a nationwide field survey of China, the largest user of plastic mulch worldwide, we found that plastic residue accumulation in cropland soils has reached 550,800 tonnes, with an estimated 6%–10% reduction in cotton yield in some polluted sites based on current level of plastic residue content. Immediate actions should be taken to ensure the recovery of plastic film mulch and limit further increase in film residue loading to maintain the sustainability of these croplands.
Plastic pollution is a global concern given its prevalence in aquatic and terrestrial ecosystems. In this paper, we found that the use of plastic mulch can indeed increase crop yields in the immediate season due to the increase of soil temperature and moisture. However, the unabated accumulation of film residues in the field negatively impacts its physicochemical properties linked to healthy soil and threatens food production in the long term. Immediate actions should be taken to ensure the recovery of plastic film mulch and limit further increase in film residue loading to maintain the sustainability of these croplands.
Abstract
Accurate and efficient real-time detection of orchard pests was essential and could improve the economic benefits of the fruit industry. The orchard pest dataset, PestImgData, was built ...through a series of methods such as web crawler, specimen image collection and data augmentation. PestImgData was composed of two parts, PestImgData-1 and PestImgData-2. It contained 24,796 color images and covered 7 types of orchard pests. Based on the PestImgData and YOLOv4 algorithm, this paper conducted a preliminary study on the real-time object detection of orchard pests from 4 perspectives: transfer learning, activation function, anchor box, and batch normalization. In addition, this paper also visualized the feature learning ability of the detection models. On the basis of the above research, three improvement measures were adopted: the post-processing NMS algorithm was upgraded to DIoU-NMS, the training method was upgraded to 2-time finetuning training and the training data was enhanced. The performance of the improved model, F-D-YOLOv4-PEST, had been effectively improved. The mean average precision of F-D-YOLOv4-PEST was 92.86%, and the detection time of a single picture was 12.22 ms, which could meet the real-time detection requirements. In addition, in the case of high overlap area or high density, F-D-YOLOv4-PEST still maintained good performance. In the testing process of the laboratory and the greenhouse, including the wired network and the wireless network, F-D-YOLOv4-PEST could locate and classify pests as expected. This research could provide technical reference for the intelligent identification of agricultural pests based on deep learning.
The Yellow River Basin, which accommodates the second longest river in China – Yellow River, covers a total area of 795,000 km2 and plays an important role in the national agricultural production, ...economy, and culture. However, the Basin also faces enormous challenges related to sustainable water management in agriculture as driven by both drought and flood. In this special issue, we collected 64 articles across the Basin to improve our understanding of agricultural water management needs and demonstrate efficacies of management practices to improve the water management. The articles present exciting research on regional soil water storage and dynamics, soil moisture conservation in rain-fed agriculture, crop water demand, irrigation effects, water-nutrient coupling, water management and soil salinity, soil and nutrient losses, groundwater science and management. Findings of studies revealed: (1) the importance of mulching, drip and negative pressure irrigation, water and nutrient coupling (i.e., fertigation) in achieving both crop production and environmental protection objectives; (2) emerging research for better understanding of regional water resources and allocation of the water resources among different agricultural land uses and cropping systems, new approaches for conserving water and soil and mitigating soil salinity, system-level integrated rainfall and irrigation management, and improved knowledge on groundwater quantity and quality management; and (3) need of future research to understand processes and efficiencies of management practices in variable landscapes and cropping systems and variable and changing climates, and system-level linkages and analyses of water balance – soil water availability and conservation – water and soil losses – agricultural and environmental sustainability.
•The annealing process is introduced into the development of a phosphate sensor.•The sensor has a large detection range and a low detection limit.•The sensor is convenient for mass-scale ...production.•It is easy to integrate the sensor into handheld equipment.
A novel method of detecting dihydrogenphosphate (H2PO4-) in aqueous solutions by electrodepositing a cobalt–iron alloy on a chip was proposed. The sensor showed a linear response to dihydrogenphosphate (H2PO4-) in the concentration range from 1×10-6M to 1×10-2M at pH 4.0 with a slope of -26.69mV/dec, giving a detection limit of 3.41×10-5M. The original chip was then annealed for 70 s at 400 °C to produce an improved version of the sensor with a linear range from 1×10-6M to 1×10-1M at pH 4.0 and a slope of -20.803mV/dec. The detection limit was 2.14×10-6M. The proposed sensor had a good, rapid response and was stable for at least 16 days. The sensor was also unaffected by the anions and cations commonly present in aquaculture water, such as NO3-, NH4+, and SO42-.
This work describes the unique capability of a novel chemical looping system that utilizes CO2 as a feedstock for methane reforming. This system uses an iron-titanium composite metal oxide and a ...co-current moving bed reactor system to yield a higher purity of syngas than the conventional CO2 dry reforming system.
An ultrasonic vortex C-Scan technique has been proposed to inspect stainless steel resistance spot welding (RSW) joints. Wavelet decomposition method is applied to analyze the original A-Scan data. ...By combination of semisoft threshold constructor and ultrasonic power ratio arithmetic (UPRA), the effect of corona bond is eliminated effectively, and its boundary is abstracted legibly. The nugget diameter measurement error is reduced from 2, approximately, to 0.19 mm. The fitted curve, nugget diameter and tensile strength, can be used to predict maximum tensile strength of joints online without destructive experiment. Shrinkage voids flaws located in the middle of the nugget have little influence on tensile strength.
Complexation of ca. 1000 ppm Pd(OAc)2 with the ligand HandaPhos (1–1.5:1) leads to a precatalyst that efficiently mediates Sonogashira couplings in aqueous nanomicelles under very mild conditions. ...Neither copper nor organic solvent is required in the reaction medium, and the product can be isolated directly from the reaction flask, leaving behind a reaction mixture that can be recycled without additional additives.
Intercropping is regarded as an important agricultural practice to improve crop production and environmental quality in the regions with intensive agricultural production, e.g., northern China. To ...optimize agronomic advantage of maize (Zea mays L.) and soybean (Glycine max L.) intercropping system compared to monoculture of maize, two sequential experiments were conducted. Experiment 1 was to screening the optimal cropping system in summer that had the highest yields and economic benefits, and Experiment 2 was to identify the optimum row ratio of the intercrops selected from Experiment 1. Results of Experiment 1 showed that maize intercropping with soybean (maize || soybean) was the optimal cropping system in summer. Compared to conventional monoculture of maize, maize || soybean had significant advantage in yield, economy, land utilization ratio and reducing soil nitrate nitrogen (N) accumulation, as well as better residual effect on the subsequent wheat (Triticum aestivum L.) crop. Experiment 2 showed that intercropping systems reduced use of N fertilizer per unit land area and increased relative biomass of intercropped maize, due to promoted photosynthetic efficiency of border rows and N utilization during symbiotic period. Intercropping advantage began to emerge at tasseling stage after N topdressing for maize. Among all treatments with different row ratios, alternating four maize rows with six soybean rows (4M:6S) had the largest land equivalent ratio (1.30), total N accumulation in crops (258 kg ha(-1)), and economic benefit (3,408 USD ha(-1)). Compared to maize monoculture, 4M:6S had significantly lower nitrate-N accumulation in soil both after harvest of maize and after harvest of the subsequent wheat, but it did not decrease yield of wheat. The most important advantage of 4M:6S was to increase biomass of intercropped maize and soybean, which further led to the increase of total N accumulation by crops as well as economic benefit. In conclusion, alternating four maize rows with six soybean rows was the optimum row ratio in maize || soybean system, though this needs to be further confirmed by pluri-annual trials.
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