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B. J. Fisher, B. J. Fisher, A. J. Poulton et al.

<p>As a net source of nutrients fuelling global primary production, changes in Southern Ocean productivity are expected to influence biological carbon storage across the global ocean. Following a high-emission, low-mitigation pathway (SSP5-8.5), we show that primary productivity in the Antarctic zone of the Southern Ocean is predicted to increase by up to 30 % over the 21st century. The ecophysiological response of marine phytoplankton experiencing climate change will be a key determinant in understanding the impact of Southern Ocean productivity shifts on the carbon cycle. Yet, phytoplankton ecophysiology is poorly represented in Coupled Model Intercomparison Project phase 6 (CMIP6) climate models, leading to substantial uncertainty in the representation of its role in carbon sequestration. Here we synthesise the existing spatial and temporal projections of Southern Ocean productivity from CMIP6 models, separated by phytoplankton functional type, and identify key processes where greater observational data coverage can help to improve future model performance. We find substantial variability between models in projections of light concentration (<span class="inline-formula"><i>&gt;</i>15 000</span> (<span class="inline-formula">µ</span>E m<span class="inline-formula">⁻²</span> s<span class="inline-formula">⁻¹</span>)<span class="inline-formula">²</span>) across much of the iron- and light-limited Antarctic zone. Projections of iron and light limitation of phytoplankton vary by up to 10 % across latitudinal zones, while the greatest increases in productivity occurs close to the coast. Temperature, pH and nutrients are less spatially variable – projections for 2090–2100 under SSP5-8.5 show zonally averaged changes of <span class="inline-formula">+</span>1.6 °C and <span class="inline-formula">−</span>0.45 pH units and Si* ([Si(OH)<span class="inline-formula">₄</span>]–[NO<span class="inline-formula"><math xmlns="http://www.w3.org/1998/Math/MathML" id="M9" display="inline" overflow="scroll" dspmath="mathml"><mrow><msubsup><mi/><mn mathvariant="normal">3</mn><mo>-</mo></msubsup></mrow></math><span><svg:svg xmlns:svg="http://www.w3.org/2000/svg" width="9pt" height="16pt" class="svg-formula" dspmath="mathimg" md5hash="1933cd4f78557ae19e1c84fa4d0b5473"><svg:image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="bg-22-975-2025-ie00001.svg" width="9pt" height="16pt" src="bg-22-975-2025-ie00001.png"/></svg:svg></span></span>]) decreases by 8.5 <span class="inline-formula">µ</span>mol L<span class="inline-formula">⁻¹</span>. Diatoms and picophytoplankton and/or miscellaneous phytoplankton are equally responsible for driving productivity increases across the subantarctic and transitional zones, but picophytoplankton and miscellaneous phytoplankton increase at a greater rate than diatoms in the Antarctic zone. Despite the variability in productivity with different phytoplankton types, we show that the most complex models disagree on the ecological mechanisms behind these productivity changes. We propose that a sampling approach targeting the regions with the greatest rates of climate-driven change in ocean biogeochemistry and community assemblages would help to resolve the empirical principles underlying the phytoplankton community structure in the Southern Ocean.</p>

Ledemar Carlos Vahl, Roberto Carlos Doring Wolter, Antônio Costa de Oliveira et al.

In flooded soils, the concentrations of exchangeable Mn²⁺ and, especially, Fe²⁺ can be high and must be considered when determining the cation exchange capacity (CEC) of the soil under flooded conditions. However, these reduced forms of Mn and Fe are oxidized and precipitated during the extraction process used in traditional CEC methods. This procedure underestimates the exchangeable portion of these cations and, consequently, the CEC value of the flooded soil. We introduce a pH-gradient-based model to predict ECEC and exchangeable Fe²⁺ in flooded soils, circumventing oxidation artifacts inherent in conventional methods. The objective of this study is to propose an alternative to estimate the exchangeable Fe²⁺ and the effective CEC (ECEC) of flooded soils. To achieve this goal, 21 surface samples (0–20 cm) of soil from rice fields were collected and distributed in the cultivation regions of southern Brazil. The soils were flooded for 50 days. The soil solution was collected on the first day and after 50 days of flooding and pH, Na, K, Ca, Mg, Fe and Mn were determined. In these samples, exchangeable cations (K, Na, Ca, Mg, Mn, Al and H + Al) were determined to calculate ECEC and CEC at pH 7 of unflooded soil and after 50 days of flooding. There was a wide range of variation in the exchangeable cation contents among the soil samples. The K contents ranged from 0.12 to 0.54 cmol_c kg⁻¹, the Na contents from 0.00 to 1.18 cmol_c kg⁻¹, the Ca contents from 0.48 to 37.31 cmol_c kg⁻¹, the Mg contents from 0.10 to 15.53 cmol_c kg⁻¹, the Mn contents from 0.01 to 0.36 cmol_c kg⁻¹, the Al contents from 0.10 to 1.74 cmol_c kg⁻¹ and the H + Al contents from 2.01 to 8.42 cmol_c kg⁻¹. The results were used to develop models to predict ECEC and exchangeable Fe content after 50 days of flooding. Estimating the ECEC after flooding using the pH gradient before and after flooding yielded values closer to CEC pH 7.0, correcting for the possible underestimation of the ECEC during flooding. The amount of exchangeable Fe estimated was higher than the exchangeable Fe determined, correcting the possible underestimation of these quantities determined during flooding. It is concluded that the estimations of ECEC after flooding through the equation <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><msub><mrow><mi>E</mi><mi>C</mi><mi>E</mi><mi>C</mi></mrow><mrow><mi>a</mi><mi>f</mi><mi>t</mi><mi>e</mi><mi>r</mi></mrow></msub><mo>=</mo><mi>E</mi><mi>C</mi><mi>E</mi><mi>C</mi><mo>+</mo><mfenced separators="|"><mrow><msub><mrow><mi>p</mi><mi>H</mi></mrow><mrow><mi>s</mi><mi>o</mi><mi>l</mi><mo>.</mo><mi>a</mi><mi>f</mi><mi>t</mi><mi>e</mi><mi>r</mi></mrow></msub><mo>−</mo><mtext> </mtext><msub><mrow><mi>p</mi><mi>H</mi></mrow><mrow><mi>s</mi><mi>o</mi><mi>l</mi><mo>.</mo><mi>b</mi><mi>e</mi><mi>f</mi><mi>o</mi><mi>r</mi><mi>e</mi></mrow></msub></mrow></mfenced><mtext> </mtext><mo>×</mo><mtext> </mtext><mstyle scriptlevel="0" displaystyle="true"><mfrac><mrow><mo>(</mo><msub><mrow><mi>C</mi><mi>E</mi><mi>C</mi></mrow><mrow><mi>p</mi><mi>H</mi><mn>7</mn></mrow></msub><mo>−</mo><mtext> </mtext><mi>E</mi><mi>C</mi><mi>E</mi><mi>C</mi><mo>)</mo></mrow><mrow><mo>(</mo><mn>7</mn><mo>−</mo><mtext> </mtext><msub><mrow><mi>p</mi><mi>H</mi></mrow><mrow><mi>s</mi><mi>o</mi><mi>l</mi><mo>.</mo><mi>b</mi><mi>e</mi><mi>f</mi><mi>o</mi><mi>r</mi><mi>e</mi></mrow></msub><mo>)</mo></mrow></mfrac></mstyle></mrow></semantics></math></inline-formula>, where <i>pH_sol.before</i> is pre-flooding soil pH, <i>pH_sol.after</i> is after flooding pH, <i>ECEC_after</i> is effective CEC after flooding and the exchangeable Fe²⁺ after flooding through the equation <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><msub><mrow><mi>F</mi><mi>e</mi></mrow><mrow><mi>e</mi><mi>x</mi><mi>c</mi><mo>.</mo><mi>a</mi><mi>f</mi><mi>t</mi><mi>e</mi><mi>r</mi><mo>.</mo><mi>e</mi><mi>s</mi><mi>t</mi><mi>i</mi><mi>m</mi><mi>a</mi><mi>t</mi><mi>e</mi><mi>d</mi></mrow></msub><mo>=</mo><msub><mrow><mi>E</mi><mi>C</mi><mi>E</mi><mi>C</mi></mrow><mrow><mi>a</mi><mi>f</mi><mi>t</mi><mi>e</mi><mi>r</mi></mrow></msub><mo>−</mo><mtext> </mtext><mfenced separators="|"><mrow><mi>C</mi><mi>a</mi><mo>+</mo><mi>M</mi><mi>g</mi><mo>+</mo><mi>K</mi><mo>+</mo><mi>N</mi><mi>a</mi><mo>+</mo><mi>M</mi><mi>n</mi></mrow></mfenced></mrow></semantics></math></inline-formula> where <i>Fe_{exc.after.estimated}</i> is estimated exchangeable Fe²⁺ after flooding corrected the problem of underestimating the values of these variables by analytical methods, demonstrating its viability for use in flood-prone soils.

Daniela Geraldine Camacho Alvarez, Johann Alexis Chávez García, Yoisdel Castillo Alvarez et al.

The agro-industry is among the largest methane emitters, posing a critical challenge for sustainability. In rural areas, producers lack effective technologies to manage daily organic waste. Anaerobic digestion (AD) offers a circular pathway by converting waste into biogas and biofertilizers; however, its adoption is limited by inappropriate designs and insufficient operational control. Theoretical-applied research addresses these barriers by improving the design and operation of small-scale biodigesters, elevating pH and Electrical Conductivity (EC) from passive indicators to first-order control variables. Based on the design of a compact biodigester previously validated in the Chillón Valley and replicated in Huaycán under a utility model patent process (INDECOPI, Exp. 001087-2025/DIN), a stoichiometric NaHCO<inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><msub><mo>⁢</mo><mn>3</mn></msub></semantics></math></inline-formula> strategy with joint pH–EC monitoring was formalized, defining operational windows (pH 6.92–6.97; EC 6200–6300 μS/cm and dose–response curves (0.3–0.4 kg/day for 3–4 day) to buffer VFA shocks and preserve methanogenic ionic strength. The system achieved stable productions of 370–462 L/day, surpassing the theoretical potential of 352.88 L/day calculated by Buswell’s equation. A multivariable predictive model (linear, quadratic, interaction terms pH × EC, temperature, and loading rate) was developed and validated with field data: R² = 0.78; MAPE = 2.7%; MAE = 11.2 L/day; RMSE = 13.8 L/day; <i>r</i> = 0.89; residuals normally distributed (Shapiro–Wilk <i>p</i> = 0.79). The proposed approach enables daily decision-making in low-instrumentation environments and provides a replicable and scalable pathway for the safe valorization of organic waste in rural areas. The design consolidates the shift from reactive to proactive and co-optimized pH–EC control, laying the foundation not only for standardized protocols and training in rural systems but also for improved environmental sustainability.

Lucas Veneziani de Toledo, Breno Justen de Castro Moreira, Leonardo Rodrigues Cadorim et al.

This study investigates the influence of inelastic electron–phonon collision time (<inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><msub><mi>τ</mi><mrow><mi>e</mi><mo>-</mo><mi>ph</mi></mrow></msub></semantics></math></inline-formula>) on the behavior of the resistive state of three-dimensional superconducting systems. Using the generalized time-dependent Ginzburg–Landau formalism, we model the interplay between vortex dynamics, energy dissipation, and thermal effects across varying values of the dimensionless parameter <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mi>γ</mi></semantics></math></inline-formula> proportional to <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><msub><mi>τ</mi><mrow><mi>e</mi><mo>-</mo><mi>ph</mi></mrow></msub></semantics></math></inline-formula> and different values of the Ginzburg–Landau parameter. The results show that larger values of <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mi>γ</mi></semantics></math></inline-formula> enhance the superconducting state by delaying the transition to the normal state, modulating critical currents, and altering differential resistance. An exponential relationship between the upper critical current and <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mi>γ</mi></semantics></math></inline-formula> is observed, indicating prolonged resistive states as the inelastic electron–phonon collision time becomes larger. Furthermore, the study investigates the maximum local peaks in the differential resistance curves, revealing their exponential decay with increasing <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mi>γ</mi></semantics></math></inline-formula>.

Mario Angel Rico-Mendez, Romeo Selvas, Oxana V. Kharissova et al.

This paper presents a pH sensor with a Mach–Zehnder Interferometer (MZI) that operates in solutions of 4.0, 7.0, and 10.0. The sensor device consists of two tapered sections with dimensions of 1 mm/1 mm/1 mm for down-taper, waist-length, and up-taper, respectively, with a separation of 10 mm. The diameter of the waist is 40 <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mi mathvariant="sans-serif">μ</mi></semantics></math></inline-formula>m. This work includes the experimental evaluation of an MZI fiber optic pH sensor at 1559 nm, where 1559 nm represents a specific wavelength chosen for its optimal sensitivity in evaluating the sensor pH detection performance. It is not the central wavelength of the optical fiber, but one of the minimal values selected to enhance the interaction between the evanescent field and the sample, ensuring the reliable detection of pH variations. These sensor dimensions and the functionalized solution of multi-walled carbon nanotubes (MWCNTs) increase the detection of pH in dyes used in the textile industry. Alizarin is a strong anionic red dye that is part of the anthraquinone dye group. The experimental results demonstrated effective detection of pH levels in water contamination involving dye. This development could resolve the problem with Alizarin. The simple fabrication, low cost, and stability of the optical response make this sensor relevant for pH measurements in water contamination.

Izabela Poplewska, Beata Strachota, Adam Strachota et al.

Protein adsorption behavior was examined on poly(<i>N</i>-isopropylacrylamide-co-sodium methacrylate)-based hydrogels at different temperatures: 5, 20, and 37 °C, and pH: 4.5, 7, and 9.2. The hydrogels, whose covalent skeleton contains pendant anionic units due to the presence of the sodium methacrylate co-monomer, exhibited both thermo- and pH-sensitivity with different extents, which depended on the content of ionizable moieties and the cross-linker density. The hydrogel composition, temperature, and pH influenced the zeta potential of the hydrogels and their swelling properties. The proteins selected for the study, i.e., bovine serum albumin (BSA), ovalbumin (OVA), lysozyme (LYZ), and a monoclonal antibody (mAb2), differed in their aminoacidic composition and conformation, thus in isoelectric point, molecular weight, electrostatic charge, and hydrophobicity. Therefore, the response of their adsorption behavior to changes in the solution properties and the hydrogel composition was different. LYZ exhibited the strongest adsorption of all proteins with a maximum at pH 7 (189.5 <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><mi mathvariant="normal">m</mi><mi mathvariant="normal">g</mi><mo> </mo><msubsup><mrow><mi mathvariant="normal">g</mi></mrow><mrow><mi>g</mi><mi>e</mi><mi>l</mi></mrow><mrow><mo>−</mo><mn>1</mn></mrow></msubsup></mrow></semantics></math></inline-formula>); adsorption of BSA and OVA reached maximum at pH 4.5 (24.4 and 23.5 <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><mi mathvariant="normal">m</mi><mi mathvariant="normal">g</mi><mo> </mo><msubsup><mrow><mi mathvariant="normal">g</mi></mrow><mrow><mi>g</mi><mi>e</mi><mi>l</mi></mrow><mrow><mo>−</mo><mn>1</mn></mrow></msubsup></mrow></semantics></math></inline-formula>), whereas mAb2 was strongly adsorbed at 9.2 (21.7 <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><mi mathvariant="normal">m</mi><mi mathvariant="normal">g</mi><mo> </mo><msubsup><mrow><mi mathvariant="normal">g</mi></mrow><mrow><mi>g</mi><mi>e</mi><mi>l</mi></mrow><mrow><mo>−</mo><mn>1</mn></mrow></msubsup></mrow></semantics></math></inline-formula>). This indicated the possibility of using the hydrogels for pH-mediated separation of proteins differing in charge under mild conditions in a water-rich environment of both the liquid solution and the adsorbed phase. The adsorption affinity of all proteins increased with temperature, which was attributed to the synergistic effects of attractive electrostatic and hydrophobic interactions. That effect was particularly marked for mAb2, for which the temperature change from 5 to 37 °C caused a twentyfold increase in adsorption. In all cases, the proteins could be released from the hydrogel surface by a reduction in temperature, an increase in pH, or a combination of both. This allows for the elimination of the use of salt solution as a desorbing agent, whose presence renders the recycling of buffering solutions difficult.

C. Wimart-Rousseau, T. Steinhoff, B. Klein et al.

<p>Since a pH sensor has become available that is principally suitable for use on demanding autonomous measurement platforms, the marine CO<span class="inline-formula">₂</span> system can be observed independently and continuously by Biogeochemical Argo floats. This opens the potential to detect variability and long-term changes in interior ocean inorganic carbon storage and quantify the ocean sink for atmospheric CO<span class="inline-formula">₂</span>. In combination with a second parameter of the marine CO<span class="inline-formula">₂</span> system, pH can be a useful tool to derive the surface ocean CO<span class="inline-formula">₂</span> partial pressure (<span class="inline-formula"><i>p</i></span>CO<span class="inline-formula">₂</span>). The large spatiotemporal variability in the marine CO<span class="inline-formula">₂</span> system requires sustained observations to decipher trends and study the impacts of short-term events (e.g., eddies, storms, phytoplankton blooms) but also puts a high emphasis on the quality control of float-based pH measurements. In consequence, a consistent and rigorous quality control procedure is being established to correct sensor offsets or drifts as the interpretation of changes depends on accurate data. By applying current standardized routines of the Argo data management to pH measurements from a pH <span class="inline-formula"><math xmlns="http://www.w3.org/1998/Math/MathML" id="M8" display="inline" overflow="scroll" dspmath="mathml"><mo>/</mo></math><span><svg:svg xmlns:svg="http://www.w3.org/2000/svg" width="8pt" height="14pt" class="svg-formula" dspmath="mathimg" md5hash="fb147fccdcf98a9911cf3d26a8f6dc33"><svg:image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="bg-21-1191-2024-ie00001.svg" width="8pt" height="14pt" src="bg-21-1191-2024-ie00001.png"/></svg:svg></span></span> O<span class="inline-formula">₂</span> float pilot array in the subpolar North Atlantic Ocean, we assess the uncertainties and lack of objective criteria associated with the standardized routines, notably the choice of the reference method for the pH correction (CANYON-B, LIR-pH, ESPER-NN, and ESPER-LIR) and the reference depth for this adjustment. For the studied float array, significant differences ranging between ca. 0.003 pH units and ca. 0.04 pH units are observed between the four reference methods which have been proposed to correct float pH data. Through comparison against discrete and underway pH data from other platforms, an assessment of the adjusted float pH data quality is presented. The results point out noticeable discrepancies near the surface of <span class="inline-formula">&gt;</span> 0.004 pH units. In the context of converting surface ocean pH measurements into <span class="inline-formula"><i>p</i></span>CO<span class="inline-formula">₂</span> data for the purpose of deriving air–sea CO<span class="inline-formula">₂</span> fluxes, we conclude that an accuracy requirement of 0.01 pH units (equivalent to a <span class="inline-formula"><i>p</i></span>CO<span class="inline-formula">₂</span> accuracy of 10 <span class="inline-formula">µ</span>atm as a minimum requirement for potential future inclusion in the Surface Ocean CO<span class="inline-formula">₂</span> Atlas, SOCAT, database) is not systematically achieved in the upper ocean.</p> <p>While the limited dataset and regional focus of our study do not allow for firm conclusions, the evidence presented still calls for the inclusion of an additional independent pH reference in the surface ocean in the quality control routines. We therefore propose a way forward to enhance the float pH quality control procedure. In our analysis, the current philosophy of pH data correction against climatological reference data at one single depth in the deep ocean appears insufficient to assure adequate data quality in the surface ocean. Ideally, an additional reference point should be taken at or near the surface where the resulting <span class="inline-formula"><i>p</i></span>CO<span class="inline-formula">₂</span> data are of the highest importance to monitor the air–sea exchange of CO<span class="inline-formula">₂</span> and would have the potential to very significantly augment the impact of the current observation network.</p>

Ayane Taki, Kouta Morioka, Keiko Noguchi et al.

Porous silica-based adsorbents for hexavalent chromium (Cr(VI)) ion removal were prepared by the combined use of functionalization with (3-glycidyloxypropyl)trimethoxysilane and the grafting of branched and linear polyethyleneimine (BPEI and LPEI). LPEI was prepared from polyethyloxazolin by hydrolysis with HCl. The preparation of LPEI was identified by NMR measurements and the grafting of BPEI and LPEI on the silica beads was confirmed by an XPS analysis. The Cr(VI) ion adsorption of the obtained BPEI-grafted silica beads (BPEI–silica beads) was investigated as a function of the pH value, the content of amino groups, the temperature, the Cr(VI) ion concentration, and the molecular mass of the grafted BPEI chains. The Cr(VI) ion adsorption at pH 3.0 increased with an increase in the content of amino groups, and the maximum adsorption capacity of 1.06 mmol/g was obtained when the content of amino groups was at 2.17 mmol/g. This value corresponds to 589 mg/g−1.8KPEI, and the adsorption ratio of about 0.5 is a noteworthy result. The data fit to the pseudo-second-order kinetic model, and the suitability of this fitting was supported by the results that the adsorption capacity and initial rate of adsorption increased with the temperature. In addition, the equilibrium data followed the Langmuir isotherm model. These results clearly demonstrate that the Cr(VI) adsorption occurred chemically, or through the electrostatic interaction of protonated amino groups on the grafted BPEI chains with hydrochromate (<inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><msubsup><mrow><mi mathvariant="normal">H</mi><mi mathvariant="normal">C</mi><mi mathvariant="normal">r</mi><mi mathvariant="normal">O</mi></mrow><mn>4</mn><mo>−</mo></msubsup></mrow></semantics></math></inline-formula>) ions. A higher adsorption capacity was obtained for the silica beads grafted with shorter BPEI chains, and the adsorption capacity of BPEI–silica beads is a little higher than that of linear PEI-grafted silica beads, suggesting that the Cr(VI) ion adsorption is affected by the chain isomerism of PEI (linear and branched) as well as the molecular mass of the grafted PEI chains, in addition to the content of amino groups. The experimental and analytical results derived from this study emphasize that the BPEI–silica beads can be used as an adsorbent for the removal of Cr(VI) ions from an aqueous medium.

V. Vlček, D. Juřička, M. Valtera et al.

<p>Around half of the Earth's soil organic carbon (SOC) is presently stored in the Northern Hemisphere permafrost region. In polar permafrost regions, low temperatures particularly inhibit both the production and biodegradation of organic matter. Under such conditions, abiotic factors such as mesoclimate, pedogenic substrate or altitude are thought to be more important for soil development than biological factors. In Antarctica, biological factors are generally underestimated in soil development due to the rare occurrence of higher plants and the short time since deglaciation. In this study, we aim to assess the relationship between SOC and other soil properties related to the pedogenic factors or properties. Nine plots were investigated along the altitudinal gradient from 10 to 320 m in the deglaciated area of James Ross Island (Ulu Peninsula) using a parallel tea-bag decomposition experiment. SOC contents showed a positive correlation with the content of easily extractable glomalin-related soil protein (EE-GRSP; Spearman <span class="inline-formula"><i>r</i>=0.733</span>, <span class="inline-formula"><i>P</i>=0.031</span>) and the soil buffering capacity (expressed as <span class="inline-formula">Δ</span>pH; Spearman <span class="inline-formula"><i>r</i>=0.817</span>, <span class="inline-formula"><i>P</i>=0.011</span>). The soil-available P was negatively correlated with altitude (Spearman <span class="inline-formula"><math xmlns="http://www.w3.org/1998/Math/MathML" id="M6" display="inline" overflow="scroll" dspmath="mathml"><mrow><mi>r</mi><mo>=</mo><mo>-</mo><mn mathvariant="normal">0.711</mn></mrow></math><span><svg:svg xmlns:svg="http://www.w3.org/2000/svg" width="55pt" height="10pt" class="svg-formula" dspmath="mathimg" md5hash="7148a909bb34bdb2df1009de6e6c5689"><svg:image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="soil-10-813-2024-ie00001.svg" width="55pt" height="10pt" src="soil-10-813-2024-ie00001.png"/></svg:svg></span></span>, <span class="inline-formula"><i>P</i>=0.032</span>), and the exchangeable Mg was negatively correlated with the rock fragment content (Spearman <span class="inline-formula"><math xmlns="http://www.w3.org/1998/Math/MathML" id="M8" display="inline" overflow="scroll" dspmath="mathml"><mrow><mi>r</mi><mo>=</mo><mo>-</mo><mn mathvariant="normal">0.683</mn></mrow></math><span><svg:svg xmlns:svg="http://www.w3.org/2000/svg" width="55pt" height="10pt" class="svg-formula" dspmath="mathimg" md5hash="367107d415f8d56a3622e3ec206d61c1"><svg:image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="soil-10-813-2024-ie00002.svg" width="55pt" height="10pt" src="soil-10-813-2024-ie00002.png"/></svg:svg></span></span>, <span class="inline-formula"><i>P</i>=0.050</span>). No correlation was found between the available mineral nutrients (P, K, Ca and Mg) and SOC or GRSP. This may be a consequence of the inhibition of biologically mediated nutrient cycling in the soil. Therefore, the main factor influencing nutrient availability in these soils does not seem to the biotic environment; rather, the main impact appears to stem from the abiotic environment influencing the mesoclimate (altitude) or the level of weathering (rock content). Incubation in tea bags for 45 d resulted in the consumption and translocation of more labile polyphenolic and water-extractable organic matter, along with changes in the C content (increase of up to <span class="inline-formula">+0.53</span> % or decrease of up to <span class="inline-formula">−1.31</span> % C) and a decrease in the <span class="inline-formula">C:N</span> ratio (from 12.5 to 7.1–10.2), probably due to microbial respiration and an increase in the abundance of nitrogen-binding microorganisms. Our findings suggest that one of the main variables influencing the SOC/GRSP content is not the altitude or coarse-fraction content (for which a correlation with SOC/GRSP was not<span id="page814"/> found); rather, we suspect effects from other factors that are difficult to quantify, such as the availability of liquid water.</p>

Yi Luo, Yongli Zhang, Yejun Wang et al.

The application of biochar is one of the promising management practices to alleviate soil acidification and improve soil fertility. However, it has been found to reduce the content of ammonium nitrogen (<inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><msubsup><mrow><mi>NH</mi></mrow><mrow><mn>4</mn></mrow><mrow><mrow><mo>+</mo></mrow></mrow></msubsup></mrow></semantics></math></inline-formula>−N) in the soil, which is the most important form of nitrogen (N) for tea tree growth. To investigate the response of soil <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><msubsup><mrow><mi>NH</mi></mrow><mrow><mn>4</mn></mrow><mrow><mrow><mo>+</mo></mrow></mrow></msubsup></mrow></semantics></math></inline-formula>−N content to the combined application of biochar and pruned tea plant litter, a pot trial was performed with three treatments: control (CK); biochar (BC); biochar + tea plant litter (BC + L). Soil chemistry properties and ammonification rates were determined, and the microbial community composition was analyzed by high-throughput sequencing. The results showed that the <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><msubsup><mrow><mi>NH</mi></mrow><mrow><mn>4</mn></mrow><mrow><mrow><mo>+</mo></mrow></mrow></msubsup></mrow></semantics></math></inline-formula>−N content in BC + L treatment was 1.7–9.5 fold higher than CK and BC treatments after 15 days of application, with no difference in the proportion of ammonia oxidation phyla such as Nitrospirae. The proportion of soil fungus Ascomycota was strongly correlated with the content of soil available nitrogen (<i>p</i> = 0.032), and the relationship was well described by a linear equation (<i>R</i>² = 0.876, <i>p</i> = 0.01). Further redundancy analysis revealed that soil pH, soil organic carbon (SOC), the ratio of SOC to total nitrogen and the ratio of SOC to alkaline hydrolyzable nitrogen appeared to be important factors influencing the separation of BC + L from CK and BC groups. In summary, the addition of biochar and pruned tea plant litter alters soil properties and may influence the composition of microorganisms with various trophic groups, thus affecting ecosystem function. Our results also highlight the importance of returning pruned materials with biochar application in tea plantation ecosystems.

Pedro Velho, Catarina S. Rebelo, Eugénia A. Macedo

Food supplements based on antioxidants and vitamins are often prescribed to correct inefficiencies in the human diet and delay diseases such as premature aging and alopecia (temporary or permanent hair loss), given the free radical scavenging activity of these biomolecules. By reducing the concentration of reactive oxygen species (ROS), which promote abnormal hair follicle cycling and morphology, follicle inflammation and oxidative stress are reduced, minimising the effects of these health issues. Gallic acid (GA), which is significantly present in gallnuts and in pomegranate root bark, and ferulic acid (FA), commonly found in brown rice and coffee seeds, are very important antioxidants for the preservation of hair colour, strength and growth. In this work, these two secondary phenolic metabolites were successfully extracted in the Aqueous Two-Phase Systems (ATPS) {ethyl lactate (1) + trisodium citrate (2) + water (3)} and {ethyl lactate (1) + tripotassium citrate (2) + water (3)} at 298.15 K and 0.1 MPa, moving towards the application of these ternary systems in extracting antioxidants from biowaste and their <i>a posteriori</i> processing as food supplements for hair fortification. The studied ATPS provided biocompatible and sustainable media for the extraction of gallic acid and ferulic acid, yielding low mass losses (<3%) and contributing to an eco-friendlier production of therapeutics. The most promising results were obtained for ferulic acid, which attained maximum partition coefficients (<i>K</i>) of 15 <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mo>±</mo></semantics></math></inline-formula> 5 and (3 <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mo>±</mo></semantics></math></inline-formula> 2) · 10¹ and maximum extraction efficiencies (<i>E</i>) of (92.7 <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mo>±</mo></semantics></math></inline-formula> 0.4)% and (96.7 <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mo>±</mo></semantics></math></inline-formula> 0.4)% for the longest tie-lines (TLL = 69.68 and 77.66 <i>m</i>%) in {ethyl lactate (1) + trisodium citrate (2) + water (3)} and {ethyl lactate (1) + tripotassium citrate (2) + water (3)}, respectively. Moreover, the effect of pH on the UV-Vis absorbance spectra was studied for all the biomolecules to minimise errors in solute quantification. Both GA and FA were found to be stable at the used extractive conditions.

Yu Abe, Michiyo Honda

<i>Enterococcus faecalis</i> (<i>E. faecalis</i>), a gram-positive facultative anaerobic bacterium, is likely to survive root canal treatment because of its extremely high alkaline tolerance, which may contribute to the refractory nature of apical periodontitis (AP). In this study, protamine was combined with calcium hydroxide to evaluate its efficacy in killing <i>E. faecalis</i>. First, the antibacterial activity of protamine against <i>E. faecalis</i> was investigated. Protamine reduced the <i>E. faecalis</i> growth rate at concentrations above the MIC (250 <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mi mathvariant="sans-serif">μ</mi></semantics></math></inline-formula>g/mL), but was not bactericidal at any of the concentrations tested. Next, we investigated the calcium hydroxide tolerance of <i>E. faecalis</i>, using a 10% 310 medium, adjusted for pH by adding a calcium hydroxide solution. The results showed that <i>E. faecalis</i> could survive and proliferate in alkaline environments up to pH 10. However, the complete killing of <i>E. faecalis</i> was observed when protamine (250 <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mi mathvariant="sans-serif">μ</mi></semantics></math></inline-formula>g/mL) was added. In addition, compared with treatment with protamine and calcium hydroxide alone, membrane damage and internalization of protamine into the cytoplasm of <i>E. faecalis</i> were enhanced. Therefore, the synergistic increase in antibacterial activity may be related to the action of both antimicrobial agents on the cell membrane. In conclusion, co-treatment with protamine and calcium hydroxide seems to be very effective in sterilizing <i>E. faecalis</i>, and has the potential to provide a novel control method against <i>E. faecalis</i> for root canal treatment.

Monika Krzywicka, Zbigniew Kobus

The goal of this study was to analyse the effect of sonoreactor dimensions on the effectiveness of the ultrasound-assisted extraction (UAE) of bioactive substances from rowan (<i>Sorbus aucuparia</i> L.). Sonication was carried out with a VC750 Sonics processor at the following amplitudes of ultrasound: 12, 24, and 36 µm. The frequency of the ultrasound was 20 kHz. Extraction was conducted in a 2 s on–4 s off pulse system. The total phenolic content and antioxidant activity were determined using a spectrophotometric method. The pH value of the extracts was measured using a combined pH metric electrode, type EPS-1 (Elmetron). Response surface methodology (RSM) was used to optimise the investigated variables. On the basis of the developed model, the following variable values were obtained: TPC—12.48 gallic acid equivalent (GAE)/g, 2,2<inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><msup><mrow></mrow><mo>′</mo></msup></semantics></math></inline-formula>-azino-bis-(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) values—126.54 <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mi mathvariant="sans-serif">μ</mi></semantics></math></inline-formula>mol Trolox (TE)/g, 2,2-diphenyl-1-picryl-hydrazyl-hydrate (DPPH) values—79.58 <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mi mathvariant="sans-serif">μ</mi></semantics></math></inline-formula>mol TE/g, ferric reducing antioxidant power assay (FRAP) values—120.65 <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mi mathvariant="sans-serif">μ</mi></semantics></math></inline-formula>mol TE/g for an extraction vessel with a diameter of 35 mm and TPC—11.68 mg GAE/g, ABTS values—120.49 <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mi mathvariant="sans-serif">μ</mi></semantics></math></inline-formula>mol TE/g, DPPH values—75.90 <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mi mathvariant="sans-serif">μ</mi></semantics></math></inline-formula>mol TE/g, FRAP values—155.54 <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mi mathvariant="sans-serif">μ</mi></semantics></math></inline-formula>mol TE/g for an extraction vessel with a diameter of 25 mm. Significant influences of time, ultrasound amplitude, and alcohol concentration on the course of the extraction process in the tested extraction vessels were found. The optimum extraction conditions for an extraction vessel with a diameter of 35 mm were obtained for an ethyl alcohol concentration of about 60%, and for an extraction vessel with a diameter of 25 mm the optimum conditions were for an alcohol concentration in the range of 30–50%. A very strong positive linear correlation was found between the concentration of ethyl alcohol and the pH value of the obtained extracts for both extraction reactors. The developed models of pulsed ultrasound-assisted extraction were characterised by a good predictive capacity (77.49–91.39%) and can be used for obtaining polyphenols from rowan.

Tuyen Vu

We consider the Dirac operator on right triangles, subject to infinite-mass boundary conditions. We conjecture that the lowest positive eigenvalue is minimised by the isosceles right triangle both under the area or perimeter constraints. We prove this conjecture under extra geometric hypotheses relying on a recent approach of Ph. Briet and D. Krej{č}i{ř}{í}k for Dirac rectangles [2].

W. Zhou, H. Jia, L. Liu et al.

<p><span class="inline-formula"><i>E</i></span> or pyriminobac-methyl (EPM), a pyrimidine benzoic acid esters herbicide, has a high potential as weedicide; nevertheless, its environmental behaviors are still not well understood. In this study, we systematically investigated, for the first time, the adsorption–desorption, degradation, and leaching behaviors of EPM in agricultural soils from five exemplar sites in China (Phaeozems – <span class="inline-formula"><i>S</i>₁</span>; Anthrosol – <span class="inline-formula"><i>S</i>₂</span>; Ferralsol – <span class="inline-formula"><i>S</i>₃</span>; Alisol – <span class="inline-formula"><i>S</i>₄</span>; Plinthosol – <span class="inline-formula"><i>S</i>₅</span>) through laboratory simulation experiments. Our results show that the EPM adsorption–desorption results were well fitted by the Freundlich model (<span class="inline-formula"><i>R</i>²<i>&gt;</i>0.9999</span>). In the analyzed soils, the Freundlich adsorption (i.e., <span class="inline-formula"><i>K</i>_f ads</span>) and desorption (i.e., <span class="inline-formula"><i>K</i>_f des</span>) coefficients of EPM varied between 0.85 and 32.22 mg<span class="inline-formula"><math xmlns="http://www.w3.org/1998/Math/MathML" id="M12" display="inline" overflow="scroll" dspmath="mathml"><msup><mi/><mrow><mn mathvariant="normal">1</mn><mo>-</mo><mn mathvariant="normal">1</mn><mo>/</mo><mi>n</mi></mrow></msup></math><span><svg:svg xmlns:svg="http://www.w3.org/2000/svg" width="26pt" height="11pt" class="svg-formula" dspmath="mathimg" md5hash="f00be694fc1cd446b33ab7313474272f"><svg:image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="soil-8-237-2022-ie00001.svg" width="26pt" height="11pt" src="soil-8-237-2022-ie00001.png"/></svg:svg></span></span> L<span class="inline-formula"><math xmlns="http://www.w3.org/1998/Math/MathML" id="M13" display="inline" overflow="scroll" dspmath="mathml"><msup><mi/><mrow><mn mathvariant="normal">1</mn><mo>/</mo><mi>n</mi></mrow></msup></math><span><svg:svg xmlns:svg="http://www.w3.org/2000/svg" width="16pt" height="11pt" class="svg-formula" dspmath="mathimg" md5hash="7e0bec708e28ccd566f3c6a6d53000dc"><svg:image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="soil-8-237-2022-ie00002.svg" width="16pt" height="11pt" src="soil-8-237-2022-ie00002.png"/></svg:svg></span></span> kg<span class="inline-formula">⁻¹</span> and 0.78–5.02 mg<span class="inline-formula"><math xmlns="http://www.w3.org/1998/Math/MathML" id="M15" display="inline" overflow="scroll" dspmath="mathml"><msup><mi/><mrow><mn mathvariant="normal">1</mn><mo>-</mo><mn mathvariant="normal">1</mn><mo>/</mo><mi>n</mi></mrow></msup></math><span><svg:svg xmlns:svg="http://www.w3.org/2000/svg" width="26pt" height="11pt" class="svg-formula" dspmath="mathimg" md5hash="2837478e44fa2f04afd915a5bf6658f1"><svg:image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="soil-8-237-2022-ie00003.svg" width="26pt" height="11pt" src="soil-8-237-2022-ie00003.png"/></svg:svg></span></span> L<span class="inline-formula"><math xmlns="http://www.w3.org/1998/Math/MathML" id="M16" display="inline" overflow="scroll" dspmath="mathml"><msup><mi/><mrow><mn mathvariant="normal">1</mn><mo>/</mo><mi>n</mi></mrow></msup></math><span><svg:svg xmlns:svg="http://www.w3.org/2000/svg" width="16pt" height="11pt" class="svg-formula" dspmath="mathimg" md5hash="37f1b14ee811e1159b86bd74c9da8085"><svg:image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="soil-8-237-2022-ie00004.svg" width="16pt" height="11pt" src="soil-8-237-2022-ie00004.png"/></svg:svg></span></span> kg<span class="inline-formula">⁻¹</span>, respectively. The mobility of EPM in soils <span class="inline-formula"><i>S</i>₁</span>–<span class="inline-formula"><i>S</i>₅</span> was categorized as immobile, slightly immobile, highly mobile, slightly mobile, and slightly mobile, respectively. Moreover, the degradation of EPM reflected first-order kinetics, where its half-life ranged between 37.46 and 66.00 d, depending on the environmental conditions, and abiotic degradation was predominant in the degradation of this compound. Overall, the high leaching ability and desorption capacity of EPM were accompanied by a low adsorption capacity, and there were no significant relationships between pH and the leaching rate of EPM in the five types of soils. In contrast, the organic matter content, cation exchange capacity, and soil clay content were the main components responsible for the observed leaching rates. We found that EPM degrades easily, has a high adsorption affinity, and a low mobility in <span class="inline-formula"><i>S</i>₁</span>, which results in a low contamination risk for groundwater systems. On the contrary, this compound degrades slowly in <span class="inline-formula"><i>S</i>₂</span>, <span class="inline-formula"><i>S</i>₃</span>, <span class="inline-formula"><i>S</i>₄</span>, and <span class="inline-formula"><i>S</i>₅</span>, due to a low adsorption affinity and moderate mobility, which results in a high contamination risk for groundwater systems. Therefore, our results may serve as a reference for evaluating the risks involved in the increasingly wide application of this compound.</p>

Luis G. Cortés, J. Barbancho, D. F. Larios et al.

This work presents a new standard in the model, identification, and control of monitoring purposes over anaerobic reactors. One requirement that guarantees a normal controller operation is for the faculty to measure the data needed periodically. Due to its inability to easily obtain the concentrations of acidogenic bacteria and methanogenic archaea periodically using reliable and commercial sensors, this paper presents an algorithm composed of an asymptotic observer (considering the reaction rates are unknown), aiming to estimate these concentrations. This method represents a significant advantage because it is possible to perform a resource-saving strategy using standard measurements, such as pH or alkalinity, to calculate them analytically in natural environments. Additionally, two yield parameters were included in the original anaerobic model two (AM2) to unlock implementations for a wide range of organic substrates. The static parameter identification was improved using a new method called step-ahead optimization. It demonstrates significant improvements fitting the mathematical model to data until a <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><mn>78.7</mn><mo>%</mo></mrow></semantics></math></inline-formula> increase in efficiency (compared with the traditional optimization method genetic algorithm). After the period of convergence, the state observer evidences a small error with a maximum <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><mn>2</mn><mo>%</mo></mrow></semantics></math></inline-formula> deviation. Finally, numerical simulations demonstrate the structure’s strengths, which constitutes a significant step in paving the way further to implement feasible, cost-effective controls and monitoring systems in the industry.

Trishen S. Gunaratnam, Dmitrii Krachun, Christoforos Panagiotis

We prove the existence of a tricritical point for the Blume-Capel model on $\mathbb{Z}^d$ for every $d\geq 2$. The proof in $d\geq 3$ relies on a novel combinatorial mapping to an Ising model on a larger graph, the techniques of Aizenman, Duminil-Copin, and Sidoravicious (Comm. Math. Phys, 2015), and the celebrated infrared bound. In $d=2$, the proof relies on a quantitative analysis of crossing probabilities of the dilute random cluster representation of the Blume-Capel. In particular, we develop a quadrichotomy result in the spirit of Duminil-Copin and Tassion (Moscow Math. J., 2020), which allows us to obtain a fine picture of the phase diagram in $d=2$, including asymptotic behaviour of correlations in all regions. Finally, we show that the techniques used to establish subcritical sharpness for the dilute random cluster model extend to any $d\geq 2$.

Jérémie Pierard de Maujouy

We clarify the structure obtained in Hélein and Vey's proposition for a variational principle for the Einstein-Cartan gravitation formulated on a frame bundle starting from a structure-less differentiable 10-manifold (arXiv:1508.07765v2 [math-ph]). The obtained structure is locally equivalent to a frame bundle. We show that under global hypotheses the formalism allows to produce variational principles which induce a frame bundle structure with a fibration over a base manifold and a variational principle on the base manifold. Our perspective on the model allows us to extend the Einstein-Cartan model to the Einstein-Cartan-Dirac theory which includes a Dirac spinor field coupled to the torsion field.

Andrea Appel, Sachin Gautam, Curtis Wendlandt

We prove a no-go theorem on the factorization of the lower triangular part in the Gaussian decomposition of the Yangian's universal $R$-matrix, yielding a negative answer to a conjecture of Khoroshkin and Tolstoy from [Lett. Math. Phys. vol. 36 1996].

Xingjia He, Sen Li, Fengzhi Wu

Intercropping plays an essential role in agricultural production, impacting the soil’s physical and chemical properties and microbial communities. However, the responses of ammonia-oxidizing microorganisms in the continuous-cropping soil to different intercropping systems in different growing seasons are still insufficiently studied. Here, we investigated the effects of seven intercropping systems (alfalfa (<i>Medicago sativa</i> L.)/cucumber, trifolium (<i>Trifolium repens</i> L.)/cucumber, wheat (<i>Triticum aestivum</i> L.)/cucumber, rye (<i>Secale cereale</i> L.)/cucumber, chrysanthemum (<i>Chrysanthemum coronrium</i> L.)/cucumber, rape (<i>Brassica campestris</i> L.)/cucumber, mustard (<i>Brassica juncea</i> L.)/cucumber) on soil physical and chemical properties, potential nitrification rate (PNR), soil ammonia-oxidizing archaea (AOA), and ammonia-oxidizing bacteria (AOB) communities in the greenhouse in spring and autumn. The results showed that, compared with cucumber monoculture, intercropping increased the soil <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><msub><mrow><mi>NH</mi></mrow><mrow><mn>4</mn><mo>+</mo></mrow></msub></semantics></math></inline-formula>-N and <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><msubsup><mrow><mi>NO</mi></mrow><mn>3</mn><mo>−</mo></msubsup></mrow></semantics></math></inline-formula>-N. The chrysanthemum–cucumber, rape–cucumber, and mustard–cucumber treatments increased soil PNR. Intercropping increased the AOA and AOB abundances in two seasons, especially in rape–cucumber, wheat–cucumber, chrysanthemum–cucumber, and trifolium–cucumber treatments. The ratio of AOA and AOB decreased with seasonal variation. The wheat–cucumber and rape–cucumber treatments increased soil AOA community diversity. Seasonal variation had a significant effect on the relative abundance of the AOB community. Nonmetric multidimensional scaling analysis showed that the AOA and AOB community structures were obviously different from spring to autumn. Redundancy analysis showed that the AOA community was significantly regulated by moisture, <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><msubsup><mrow><mi>NO</mi></mrow><mn>3</mn><mo>−</mo></msubsup></mrow></semantics></math></inline-formula>–N, and available potassium (AK), while the AOB community was significantly regulated by moisture, available phosphorus (AP), AK, <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><msubsup><mrow><mi>NO</mi></mrow><mn>3</mn><mo>−</mo></msubsup></mrow></semantics></math></inline-formula>-N, and pH. Network analysis showed that the co-occurrence relationship and complexity of AOA and AOB communities were different in two growing seasons. The AOB community may play a critical role in ammonia oxidation in autumn. Taken together, intercropping improved soil physicochemical state, increased soil PNR and significantly altered soil AOA and AOB communities. Seasonal variation significantly altered the AOA and AOB communities’ structure and interaction between them. The effect of seasonal variation on AOA and AOB communities was greater than intercropping.