Mineralization Rates Research Articles

The Effect of Manure‐Based Fertilisers on Nitrogen Mineralisation and Greenhouse Gases Emissions After Soil Application

ABSTRACTThe continuous increase of costs with mineral fertilisers made farmers search for alternatives, while livestock producers face strong challenges to, sustainably, manage large amount of manure. It is, therefore, important to provide strategies that could enhance the use of manures in agriculture, recycling nutrients and organic matter. This study aimed to evaluate the use of manure‐based fertilisers (MBFs), with tailored N:P2O5 ratios, to values commonly used by farmers: 1:1, 2:1 and 0.5:1. These MBFs were applied to a sandy soil and the resulting nitrogen mineralisation, nitrification rates and greenhouse gases emission were measured. Raw manures (cattle slurry [CaS], pig slurry [PiS] and poultry manure [PoM]) were used directly to obtain the 1:1 N:P2O5 ratio. For the 2:1 ratio, two MBFs were produced with each raw manure, plus the addition of urea or ammonium sulphate to provide additional N. To prepare the P richer fertiliser with a 0.5:1 ratio, the pig slurry solid fraction was used on its own, while the CaS and PoM were blended with superphosphate (SP) or with phosphoric acid, to provide additional P. In the 1:1 ratio, both slurries had higher mineralisation rates (~35% of the organic N applied) and lower environmental impact, compared with PoM. Blending PoM with urea, for the 2:1 ratio, improved the N mineralisation rate, while decreasing the N2O and CO2 emissions to almost half the value observed with the raw PoM, enhancing its fertiliser value. The addition of SP to PoM decreased the N2O emissions and presented a similar nitrification rate as the raw material. The results demonstrate that it is possible to produce MBFs with these specific N:P2O5 ratios, with potential agronomical and environmental benefits, compared with the raw material.

Biomineralization of Cd2+ and Pb2+ by sulfate-reducing bacteria Desulfovibrio desulfuricans and Desulfobulbus propionicus

Sulfate reducing bacteria (SRB) is considered to be the most promising alternative biological treatment for immobilization of heavy metals due to its high efficiency and low cost. However, the mechanism underlying the biomineralization process has remained unclear. In this study, the kinetics and effects of Cd2+ and Pb2+ mineralization by sulfate-reducing bacteria Desulfovibrio desulfuricans and Desulfobulbus propionicus were investigated based on the microbial treatment technology, and the scanning electron microscope and energy dispersive spectroscopy (SEM-EDS), transmission electron microscope (TEM), X-ray diffractometer (XRD), Raman spectra and X-ray photoelectron spectroscopy (XPS), were used to reveal the mechanism of SRB treatment. The results showed that D. propionicus had a more efficient heavy metal mineralization rate than the D. desulfuricans, up to 98.97% and 75.62% at initial Cd2+ concentrations of 30 and 60 mg/L particularly. respectively. Both D. desulfuricans and D. propionicus had achieved 80% immobilization efficiency of Pb2+ with an initial Pb2+ concentration less than 50 mg/L. D. desulfuricans and D. propionicus facilitate the precipitation of Cd2+ and Pb2+ in the solution primarily as CdS, while Pb were mineralized and removed through phosphate and oxide precipitates of Pb and PbS via their metabolic activities involving sulfate conversion. This research suggested that mineralization of heavy metals mediated by microbial sulfate reduction should have prospects for broad application in bioremediation of mine drainage.

A meta-analysis of warming and precipitation change effects on soil nitrogen cycles

Abstract Global warming and altered precipitation regimes may profoundly affect soil nitrogen (N) transformations. However, a comprehensive understanding of how soil N cycling responds to such climatic changes remains lacking, with few syntheses of field-based observations. Here, a meta-analysis was conducted using 755 paired data points from field observations worldwide to explore the effects of warming and altered precipitation on soil N transformation rates and to assess possible drivers of these effects. Warming positively affected the soil N mineralization and nitrification rates (+21.8% and +20.9%), but had no effect on the microbial immobilization rate. Similarly, increased precipitation accelerated soil N mineralization and nitrification (+10.2% and +9.4%), but did not alter microbial immobilization. In contrast, decreased precipitation did not affect any of the three N transformation rates. Moreover, warming effects on the N mineralization rate were mainly driven by the variations in soil moisture and soil total N content, while effects on the nitrification rate were regulated by changes in ammonia-oxidizing bacterial abundance. In addition, effects of increased precipitation on the N mineralization rate were largely dependent on changes in soil moisture and experimental manipulation characteristics, while effects on the nitrification rate were shaped by MAP, soil pH, ecosystem types, and treatment duration. Overall, increased temperature and precipitation accelerated soil N cycling and increased soil N availability, but decreased precipitation did not. These findings may improve predictions of biogeochemical cycling under future climate change scenarios.

Photocatalysis and phosphorus drive organic production in algal-bacterial co-cultures treating oil sands process affected water.

Photocatalysis and phosphorus drive organic production in algal-bacterial co-cultures treating oil sands process affected water.

Exploring carbon dynamics in a slow sand filter using stable isotopes.

Exploring carbon dynamics in a slow sand filter using stable isotopes.

Biodegradation and mineralization of bisphenol A by a novel soil-derived fungus Paraconiothyrium brasiliense mediated by extracellular laccase.

Biodegradation and mineralization of bisphenol A by a novel soil-derived fungus Paraconiothyrium brasiliense mediated by extracellular laccase.

Boosting biodegradation and mineralization efficiencies of chlorinated VOCs: The synergy of H2O2 and biotrickling filtration.

Boosting biodegradation and mineralization efficiencies of chlorinated VOCs: The synergy of H2O2 and biotrickling filtration.

How far do we still need to go with antibiotics in aquatic environments? Antibiotic occurrence, chemical-free or chemical-limited strategies, key challenges, and future perspectives.

How far do we still need to go with antibiotics in aquatic environments? Antibiotic occurrence, chemical-free or chemical-limited strategies, key challenges, and future perspectives.

Optimizing Hemp (Cannabis sativa L.) Residue Management: Influence on Soil Chemical Properties Across Different Application Technologies

The use of crop residues is increasing across farming systems as part of climate change mitigation efforts and agricultural management practices to improve soil health. Hemp residues offer valuable potential in these efforts due to their rich nutrient composition. However, the complex chemical composition of hemp residue could pose a significant challenge by slowing the decomposition rate if not adequately managed. The aim of this study is to evaluate the influence of different timings of hemp residue incorporation, soil tillage practices, and mode of application on the rate of mineralization and soil chemical parameters. A complete randomized design field trial was conducted on hemp (Cannabis sativa L.) residue incorporation across different seasonal periods and modes of application. The results showed that the fastest mineralization occurred when hemp residue was incorporated in autumn, while the slowest mineralization was observed when the residue was left on the surface of the soil as mulch. The application of hemp residues over three years led to a slight increase in soil pH from an initial value of 4.9; however, this change was not statistically significant. Similarly, nitrogen content did not change significantly between the different periods after applying hemp residues. In contrast, hemp residues contributed to an increase in soil carbon content. Overall, this study emphasizes the need to optimize hemp residue management to maximize its benefits for enhancing soil chemical properties and promoting sustainable agriculture.

Phosphorus Mineralization Dynamics in Acidic Eastern Himalayan Soils: Implications for Sustainable Tribal Agriculture

The sustainable livelihood of the indigenous populations residing in the Eastern Himalayas can be maintained through traditional management practices utilizing locally available organic resources. However, knowledge gaps exist regarding nutrient management, particularly phosphorus (P), in acidic hill soils. Additionally, data on the P mineralization (Pmin) rates of various organic sources used in the area are lacking. To address this gap, an incubation study with the aim to determine the kinetics and rate of P mineralization of different local organic sources of North East region of India was conducted with various treatments, including Farm Yard Manure (FYM) (T1), poultry manure (T2), pig manure (T3), and vermi-compost (T4), applied at a rate of 120 kg N/ha equivalent in a Completely Randomized Design replicated four times. Observations were made at 10-days interval over a period of 100 Days Of Incubation (DOI). Results indicated that the highest Pmin rate was observed in T2 (6.66%) > T3 (6.54%) > T4 (6.37%) > T1 (5.74%) compared to the control (T0). Pmin rates positively correlated with soil attributes such as pH (0.86*), EC ( 0.75*), CEC (0.95*) and negatively with SOC ( -0.99*). First-order kinetics revealed the highest Pmin with T2 (R2= 0.96) while second-order kinetics indicated highest for T3 (R2 =0.61). The pattern of Pmin rate showed a gradual increase starting from 20 DOI onwards. Notably, pig manure (T3) exhibited the highest mineralization rate during the initial period, specifically between 10-30 DOI. It is concluded that high Pmin rates were recorded between 50-90 DOI, with the peak occurring recorded at 70 DOI with T2.

Characteristics of leaf nutrient resorption efficiency in Tibetan alpine permafrost ecosystems

Nutrient resorption is an important strategy for nutrient conservation, especially in permafrost ecosystems where plant growth is limited by nutrients. Based on the measurements mainly derived from tropical, subtropical and temperate regions, current projections suggest that resorption efficiency is higher for leaf nitrogen (N) than for phosphorus (P) in cold regions. However, these projections have not been fully validated due to the lack of observations in permafrost ecosystems. Here, we carry out a large-scale sampling campaign along a permafrost transect on the Tibetan Plateau. Our results show that, in contrast with the prevailing view, resorption efficiency is higher for leaf P than N in permafrost ecosystems (75.1 ± 1.8% vs. 58.7 ± 1.5%; mean ± standard error). Our results also reveal that leaf P resorption efficiency is higher in permafrost ecosystems than in global herbaceous plants, while there is no difference for leaf N resorption efficiency. Interestingly, there is a trade-off between leaf N resorption efficiency and soil N mineralization rate, but no such pattern exists for P. These results illustrate the unique characteristics of plant nutrient resorption in permafrost ecosystems and advance our understanding of nutrient conservation strategies in little-studied permafrost regions.

Application of Multi-Source Data Mining Technology in the Optimization of Prospecting Target Areas for Copper Deposits in the Beishan Region of Gansu Province, China

The effectiveness of geological prospecting depends on the accuracy of the prediction of the prospecting target areas. In comparison with the conventional qualitative method (Mineral Exploration and Development), the use of big data concepts and methods for the in-depth analysis of the potential value of geological information has emerged as an effective way to improve the accuracy of prospecting target area predictions. The Beishan area in Gansu Province, China, is a prominent polymetallic metallogenic belt in northwest China. In recent years, geologists have encountered challenges in achieving effective breakthroughs in prospecting through conventional methods. In this study, we apply the big data concepts and methods to analyze the geochemical and aeromagnetic data of the Beishan area and utilize a series of self-developed software to rectify errors in the original data. A new geochemical remediation plan is proposed for the main elements of ore formation, and on this basis, a copper ore prospecting model based on multi-source data information mining is established. The prospecting model is used to predict the formation of copper ore in the Beishan area, and 100 level I and II preferred target areas with significant prospecting significance have been identified. Level I and II preferred target areas account for 2.7% of the study area. Verified by field sampling, the actual mineralization rate of the level I target area is 39.47%. This study proves the effectiveness of the proposed multi-source data mining method in improving the prediction accuracy of prospecting target areas.

Transformation of maize photosynthetic carbon in reconstructed soils

IntroductionThe gully erosion control and land construction project was a major land improvement project implemented by human beings to increase the cultivated land area and improve the quality of cultivated land, and the implementation of the project had a great intervention and influence on the carbon cycle.MethodsThe microcosm experiment was carried out to reveal carbon cycle process of maize photosynthetic carbon in reconstructed soils during gully reclamation using a14C continuous labeling technique. The experimental soil came from Nanniwan Town, Yan’an City.ResultsThe distribution ratios of photosynthetic carbon in plants, roots and reconstructed soils were 83.96%–85.19%, 9.47–10.55% and 5.49–5.62%, respectively. It was revealed that the renewal rates of the dissolved organic carbon (DOC), microbial biomass carbon (MBC) and soil organic carbon (SOC) in reconstructed soils were 6.72%–14.64%, 1.70%–7.67% and 0.73%–1.99%, respectively.DiscussionThe distribution and transformation of maize photosynthetic carbon had a greater impact on the changes in the DOC and MBC that SOC. It was found that the mineralization rate of maize photosynthetic carbon in reconstructed soils was higher than 0.6 μg/g·d after construction, but with the extension of cultivation time, it slowed down, the decreasing rate increased, and finally stabilized at about 0.15 μg/g·d.

The Development of a New Bi12ZnO20/AgI Heterosystem for the Degradation of Dye-Contaminated Water by Photocatalysis Under Solar Irradiation: Synthesis, Characterization and Kinetics

This study explores the efficiency of heterogeneous photocatalysis in wastewater treatment, which is recognized for inducing significant rates of degradation and mineralization of various contaminants, including dyes. The study focuses on the development of an innovative composite via a combination of the sillenite type semiconductor Bi12ZnO20 and the halide-type semiconductor AgI. Both semiconductors were synthesized via co-precipitation, and their phases were identified using X-ray diffraction and characterized by scanning electron microscopy, Raman spectroscopy, Brunauer–Emmett–Teller analysis for specific surface area, UV–Visible diffuse reflectance spectroscopy, and the point of zero charge. The evaluation of the photocatalytic activity of the Bi12ZnO20/AgI heterosystem was carried out by monitoring the degradation process of Basic Blue 41 (BB41) under solar irradiation conditions. The results of this study revealed that the Bi12ZnO20/AgI heterosystem achieved the efficient degradation of BB41, with a removal rate of 98% after 150 min of treatment. The mineralization study showed that the TOC value decreased from 19.89 mg L−1 to 6.87 mg L−1, indicating that a significant portion of BB41 was mineralized. Via kinetic research, it was established that the degradation process followed a pseudo-first-order mechanism. Furthermore, recycling tests showed that the synthesized heterostructures maintained good structural stability and acceptable reusability over several cycles. These findings highlight the potential of heterogeneous photocatalysis as a promising approach to addressing environmental challenges associated with azo dyes.

Diversifying endpoints in biodegradation testing of microplastics

To counteract microplastic (MP) pollution the European Commission adopted a restriction of intentionally adding synthetic polymer microparticles to products, such as detergents, rinse-off cosmetics, controlled-release fertilizers or pesticides. Exempted are particles consisting of polymers that, e.g., meet the (bio)degradability pass criteria of the available test methods. The main criterion for proving biodegradability is the particle’s mineralization rate, as set out, amongst others, in OECD testing guidelines 301B referenced by the REACH regulation of the European Union. Since present test methods are designed and validated to test low-molecular, soluble compounds adaptations regarding MP biodegradability testing are of high interest. In this study, the biodegradability of a polyurea (PUA) microcapsule suspension was tested using a standard degradation test method (OECD test guideline (TG) 301B). Since the polymeric component comprised less than 1% of the suspension, besides the aromatic solvent inside the microcapsule (8.6%) and water (90.9%), 14C-labeling of the polymer was essential for specific detection throughout the experiments. Particle size determination of the tested PUA microcapsules indicated a bias in the test results due to the presence of a soluble 14C-compound, a byproduct of synthesis, identified using ultra-high performance liquid chromatography–high resolution mass spectrometry (UHPLC–HRMS) coupled with radioactivity detection. This study highlights the need for proper characterization and purification of the tested particles prior to biodegradation testing and suggests how to diversify future regulatory testing for a comprehensive assessment of the biodegradation of MPs.Graphical abstract

Transforming the Poison Effects of Water Vapor into Benefits Over Adjustable Dual Acid Sites for Stable Plasma-Catalysis.

Developing a new strategy to address water vapor poisoning is crucial for catalysts in real-working conditions. Except for the traditional thinking of resistance enhancement, a reverse idea is proposed herein of utilizing the inevitable H2O, converting it to active ·OH to enhance the overall performance, with the help of O3 and high energy electrons (e*) in plasma. Dual active sites of Lewis acid (Y3+) and Mn on YxMnyOx+2y catalyst promote the co-adsorption of H2O and O3, and the dissociation of H2O to surface hydroxyl species (*OH). A new OH-accompanied pathway for O3 decomposition is formed and a new intermediate species (*OOH) with a lower energy barrier (0.77eV lower than traditional *O2 2-) is detected, in which e* in plasma can further accelerate its desorption. Thereafter, abundant active ·OH are generated and work for pollutants degradation, achieving 99.78% ethyl acetate (EA) degradation and 97.36% mineralization rate on the surface of YMO (1:2) under humid environment, with excellent long-term stability. The changed activation site of C─O bond in EA, different by-products, and reaction pathways are also analyzed. This active species regulation strategy transforms the traditional poison effects of water vapor into great benefits, paving the way for broader catalyst applications free of water vapor.

Bifunctional Catalyst ZVI@PDA Mediated the Reduction Coupling Oxidation Reaction of Triclosan to Achieve a High Mineralization Rate

Bifunctional Catalyst ZVI@PDA Mediated the Reduction Coupling Oxidation Reaction of Triclosan to Achieve a High Mineralization Rate

Responses of Soil Nitrogen Transformation and N2O Emission to Soil pH and Hydrothermal Changes

Soil nitrogen fate determines nitrogen availability for crops and their environmental impact, which is regulated by nitrogen transformation processes that are mediated through soil properties (e.g., pH) and environmental factors (e.g., hydrothermal conditions). Incubation experiments were conducted on soils with different pH levels (covering acidic to calcareous ranges) to study the effects of soil pH and hydrothermal conditions on nitrogen transformation and N2O emissions. The results showed that the net ammonification rate was negatively correlated with soil pH, whereas the net nitrification rate, net nitrogen mineralization rate, and N2O emission rate showed positive correlations. Structural equation modeling (SEM) indicated that soil pH and hydrothermal conditions exerted primary influences on soil net nitrogen transformation rates, consequently affecting N2O emissions. Soil pH and hydrothermal conditions had 83% and 93% effects, respectively, on net nitrogen transformation rates, while they had 77% effects on N2O emissions. Consequently, soil pH and hydrothermal conditions might be the key drivers influencing soil nitrogen transformation and N2O emissions. Specifically, in subtropical regions characterized by high temperatures and abundant summer rainfall, regulating soil moisture could mitigate NO3−-N accumulation and N2O emissions, providing a targeted strategy for sustainable nitrogen management.

Analyzing flotation bubble breakup behavior in stirring equipment based on SST k-ω model and VOF model

ABSTRACT Flotation is a pivotal technique for separating fine, low-grade minerals, where bubble dynamics and breakup mechanisms critically influence efficiency and selectivity. This study employs the SST k-ω turbulence model and VOF model to explore multiphase flow characteristics in a stirring tank at various impeller speeds, analyzing bubble ascent and breakup behavior. Results show intense bubble breakup regions coincide with vortex-rich areas, highlighting the crucial role of tail vortices. Further analysis reveals that turbulent breakup mechanisms are driven by rotational flows and shear flows caused by vortex interactions. Viscous shear stress from tail vortices is identified as the primary driver 006Ff bubble breakup. The mechanisms of bubble breakup vary with location relative to the impeller, providing a theoretical basis for optimizing flotation equipment. This study enhances the recovery rates of low-grade minerals and improves the selectivity and efficiency of the flotation process.

Selective inhibition experiments and molecular dynamics calculations for coal slurry

ABSTRACT The interactions among dextrin, sodium hexametaphosphate, sodium silicate, and three minerals (kaolinite, quartz, and coal sample) were examined through a combination of flotation experimentals and molecular dynamics simulations. The single inhibitor flotation experimental shows that the three inhibitors can inhibit the flotation of gangue minerals and improve the recovery rate of valuable minerals in the order of sodium silicate > dextrin > sodium hexametaphosphate. In composite inhibitor flotation experimentals, it was observed that when the dosage of dextrin-sodium silicate (1:1) reached 1000 g/t, the coal slurry could be processed to achieve an ash content of 10.69% along with a yield of 65.15% for coal. Molecular dynamics simulations indicated that dextrin primarily physisorbed onto all three minerals; notably, its interaction with kaolinite was most robust, followed by quartz and then coal sample. Sodium hexametaphosphate interacted with kaolinite to form O-Al and O-Si ionic bonds while establishing Na-O ionic bonds with quartz. During interactions between sodium silicate and kaolinite, oxygen from silicate engaged in ionic bonding with silicon and aluminum from kaolinite; additionally, it formed Na-O ionic bonds with quartz. These interactions occurred through electrostatic potential energy as well as non-bonding energy contributions; their strength ranked in order from strongest to weakest as follows: kaolinite, quartz, and coal sample. Upon comparing interaction energies across different scenarios, it was determined that sodium silicate emerged as the most effective selective inhibitor for chalcopyrite minerals followed closely by dextrin. Furthermore, simulations involving the composite inhibitor formulation of dextrin-sodium silicate (1:1) alongside each mineral revealed that their synergistic effect surpassed that of individual inhibitors alone, a finding consistent with results obtained from composite inhibitor flotation experimentals and further substantiated the accuracy of molecular dynamics simulation outcomes.