Total Nitrogen Content Research Articles

A Field Study to Assess the Impacts of Biochar Amendment on Runoff Quality from Newly Established Green Roofs

Green roofs (GRs) are a widely recognized green infrastructure (GI) strategy that helps reduce runoff volume and runoff pollution caused by the significant increase in impervious urban areas. However, the leaching of several nutrients from GR substrates is a growing concern. Biochar, a carbon-rich material, possesses advantageous properties that can help address such environmental challenges associated with GRs. Therefore, this paper aimed to undertake a field study to investigate the impacts of various biochar application methods, particle sizes, and amendment rates on the quality of runoff from GRs. Observational data of runoff quality were collected over a two-month period from five newly established 1 m × 1 m biochar-amended GR test beds and a control test bed without biochar, with all test beds subjected to artificially simulated rainfall. The results indicated that the addition of biochar did not result in a significant improvement in runoff pH, whereas the electrical conductivity (EC) was higher in runoff from GRs with biochar-amended substrates. When comparing the total nitrogen (TN) concentration in runoff from the non-biochar GR (ranging from 3.7 to 31 mg/L), all biochar test beds exhibited higher TN release (4.8 to 58 mg/L), except for the bed where medium biochar particles were applied at the bottom of the substrate (ranging from 2.2 to 21 mg/L). Additionally, all biochar-amended GRs exhibited higher TP concentrations in runoff (0.81 to 2.41 mg/L) when compared to the control GR (0.35 to 0.67 mg/L). Among the different biochar setups, GR with fine biochar particles applied to the surface of the substrate had the poorest performance in improving runoff water quality. Despite these mixed results, biochar holds significant potential to improve runoff quality by significantly increasing water retention, thereby reducing pollutant loads.

Riverine concentrations and export of dissolved silicon, and potential controls on nutrient stoichiometry, across the land–ocean continuum in Great Britain

Silicon (Si) is an essential nutrient element in freshwater and marine ecosystems, and its abundance relative to macro-nutrients (N, P) can impact phytoplankton communities in eutrophic rivers and estuaries. This study is the first national assessment examining (i) the primary sources (geological, biological, landcover) and controls (geomorphological, precipitation) on the transport of terrestrial dissolved silicon across Great Britain to the ocean, and (ii) the current extent and nature of its interactions with macro-nutrients in these catchments in relation to its potential impacts on phytoplankton community structure. It uses results from a year-long survey of 41 rivers along with historical data. Highest concentrations of dissolved Si (4–5.5 mg L-1) were found in rivers of the chalk- and sedimentary sandstone-based catchments of southern Great Britain and the hard sandstone catchments of Scotland. Catchment yield rates for dissolved Si varied between 0.2 and 2.6 t km−2 yr−1, with highest yields found in catchments with higher precipitation and runoff. Analysis of river N:P and dissolved Si:N ratios suggested that the sampled rivers were typically N enriched, and P limited with respect to dissolved Si. Molar dissolved Si:N ratios < 1, an indicator of river eutrophication, were associated with total nitrogen concentrations exceeding 1.8 mg L-1 or greater. The Indicator of Coastal Eutrophication index was used to assess the potential role of dissolved Si in the eutrophication of coastal waters. Negative values indicating limited eutrophication potential to non-siliceous algae were generally found, although some rivers had annual Indicator of Coastal Eutrophication index values exceeding 0, with values as high as 35 kg C km−2 day−1. In many eutrophic rivers, high dissolved Si concentrations derived from catchment lithology, kept the Indicator of Coastal Eutrophication index values below zero. Results have demonstrated that high N and P export have likely shifted most Great Britain rivers and coastal waters beyond the stoichiometric range where diatoms dominate production and into one where non-siliceous algae maybe increasingly present. Thus, future assessments of macro-nutrient management schemes, such as those involving wetlands should include dissolved Si routinely due to its stoichiometric importance.

Soil Erosion Thickness and Seasonal Variations Together Drive Soil Nitrogen Dynamics at the Early Stage of Vegetation Restoration in the Dry-Hot Valley.

By changing the physicochemical and biological properties of soil, erosion profoundly affects soil nitrogen levels, but knowledge about the erosion impact on soil nitrogen (N) dynamics is still rather incomplete. We compared soil N contents at the early stage of vegetation self-restoration in response to soil erosion thickness (0, 10, 20, 30 and 40 cm), by conducting a simulated erosion experiment on sloping arable land in the dry-hot valley of Yunnan Province, southwestern China. The results showed total nitrogen (TN), ammonium nitrogen (NH4+-N) and nitrate nitrogen (NO3--N) contents reduced with increasing soil erosion thickness and decreased significantly at the soil erosion thickness of 10, 40 and 10 cm in the rainy season and 30, 10 and 10 cm in the dry season compared with 0 cm. Structural equation modeling (SEM) indicated that soil erosion thickness and seasonal variation were the important drivers of mineral nitrogen (NH4+-N and NO3--N) content. Soil erosion thickness indirectly affected mineral nitrogen through negative on TN, carbon content and Diazotrophs (nifH genes). Dry-wet season change had an effect on mineral nitrogen mediated by arbuscular mycorrhizal fungi (AMF) and nifH genes. We also found AMF had a promotion to nifH genes in eroded soil, which can be expected to benefit nitrogen fixing. Our findings highlight the importance of considering soil erosion thickness and sampling time for nitrogen dynamics, in particular, the investigation of nitrogen limitation, in the early stage of vegetation self-restoration.

Novel Halogenated Curcumin-Mediated Photodynamic Inactivation for the Preservation of Small Yellow Croaker (Larimichthys polyactis).

A novel class of halogenated curcumin, X-Cur (X = F, Cl, or Br), was synthesized, and its photosensitivity was evaluated. The results showed that Br-Cur with the highest singlet oxygen (1O2) generation capacity exhibited a better photodynamic inactivation (PDI) effect on the small yellow croaker (Larimichthys polyactis) than curcumin. This was attributed to the heavy atom effect of Br, which resulted in Br-Cur having the smallest singlet-triplet energy difference ΔEst(S1-T3) (0.140 eV) and the largest spin-orbit coupling value (0.642262 cm-1). When L. polyactis was treated with 0.025 wt % Br-Cur and exposed to blue LED irradiation (450 nm, 20 mW/cm2) for 20 min, the increase in the total volatile basic nitrogen content (28.23 ± 2.38 mg/100 g on day 6), pH, and total viable count (6.13 ± 0.06 log CFU/g on day 6) could be effectively controlled. Accordingly, Br-Cur is a promising photosensitizer for PDI preservation.

Role of the intestines on the muscle quality of Pacific white shrimp (Litopenaeus vannamei) during chilled storage: Physicochemical and label-free–based peptidomics analyses

The effect of shrimp deveining on the quality of Pacific white shrimp muscle was investigated by analyzing the protein degradation during chilled storage via physicochemical and label-free peptidomics analyses. In this study, shrimp with intact intestines were in the control group (CS), while deveined shrimp (DS) were in the treatment group. The total viability count (TVC), total volatile base nitrogen (TVB-N) content, and trichloroacetic acid (TCA)-soluble peptide content in all of the shrimp groups gradually increased with prolonged chilled storage. However, in the later stages of chilled storage, the DS samples exhibited significantly lower TVB-N, total bacterial, and TCA-soluble peptide contents than the CS samples, indicating that deveining treatment effectively prolonged shrimp quality. The peptidomics analysis revealed varying degrees of protein hydrolysis in the DS and CS samples during chilled storage. A total of 396 differentially abundant peptides (DAPs) were identified in the DS compared with the CS, comprising 98 upregulated and 298 downregulated segments. This suggests that the removal of the intestine effectively inhibits protein hydrolysis. Gene ontology (GO) analysis suggested that the DAPs were mainly involved in catalytic activity, binding, and metabolic processes. The cluster of orthologous groups of protein (COG) analysis showed that the cytoskeleton dynamics of the muscle proteins underwent considerable alterations influenced by the shrimp's intestines during chilled storage.

Comprehensive Study of Total Nitrogen Content and Microfluidic Profiles in Additive-Enriched Plant-Based Drinks.

The growing consumption of plant-based milk substitutes raises important questions about their composition. The various additives used by manufacturers, including those employed as flavor enhancers, protein additives, and stabilizers, may contain both protein and non-protein nitrogen components. In our study, we examined not only popular milk alternatives but also other milk substitutes made from specific plants. We present a reproducible and rapid method for the simultaneous qualitative and quantitative determination of the total nitrogen content in milk alternatives, focusing on applicability. Using the microchip gel electrophoretic method, we determined that the total nitrogen content differed from the protein content indicated on the packaging. Our results, along with statistical evaluations, supported the hypothesis that different brands of products, derived from the same plant source, resulted in different microfluidic profiles, likely due to the presence of additives. As expected, the microfluidic profiles of additive-free products differed from those of fortified products made from the same plant-based milk replacer. Total nitrogen content provides crucial information for individuals with kidney disease, as is essential to reduce the burden on the kidneys to slow deterioration, alleviate symptoms and avoid complications.

Seed endophytes and rhizosphere microbiome of Imperata cylindrica, a pioneer plant of abandoned mine lands.

Some plant-associated microorganisms could improve host plants biotic and abiotic stress tolerance. Imperata cylindrica is a dominant pioneer plant in some abandoned mine lands with higher concentrations of heavy metal (HM). To discover the specific microbiome of I. cylindrica in this extreme environment and evaluate its role, the microbiome of I. cylindrica's seeds and rhizosphere soils from HM heavily contaminated (H) and lightly contaminated (L) sites were studied. It was found that HM-contamination significantly reduced the richness of endophytic bacteria in seeds, but increased the abundance of resistant species, such as Massilia sp. and Duganella sp. Spearman's rank correlation coefficient analysis showed that both Massilia sp. and Duganella sp. showed a significant positive correlation with Zn concentration, indicating that it may have a strong tolerance to Zn. A comparison of the microbiome of rhizosphere soils (RS) and adjacent bare soils (BS) of site H showed that I. cylindrica colonization significantly increased the diversity of fungi in rhizosphere soil and the abundance of Ascomycota associated with soil nutrient cycling. Spearman's rank correlation coefficient analysis showed that Ascomycota was positively correlated with the total nitrogen. Combined with the fact that the total nitrogen content of RS was significantly higher than that of BS, we suppose that Ascomycota may enhance the nitrogen fixation of I. cylindrica, thereby promoting its growth in such an extreme environment. In conclusion, the concentration of HM and nutrient contents in the soil significantly affected the microbial community of rhizosphere soils and seeds of I. cylindrica, in turn, the different microbiomes further affected soil HM concentration and nutrient contents. The survival of I. cylindrica in HM severely contaminated environment may mainly be through recruiting more microorganisms that can enhance its nutrition supply.

Nutritional quality of tomato in response to different fertilization doses and conduction systems

The tomato, a rich source of essential nutrients such as vitamins A and C, potassium, and antioxidants, plays a crucial role in human nutrition, promoting health and preventing diseases. In Brazil, its production is vital, involving significant resources and labor. The correct nutritional management of the crop can improve the nutritional attributes of tomato fruits, therefore the correct use of fertilizers is of great importance due to the high need for phosphorus, nitrogen and potassium, throughout the crop cycle. Nutritional management is of great importance in tomato fields due to its high fertilizer requirements throughout the entire crop cycle. This study aimed to assess the effect of different fertilizer doses and management systems on the physicochemical characteristics of tomatoes. The experiment followed a factorial design with five fertilizer doses (A0: 0%; A1: 50%; A2: 100%; A3: 150%; A4: 200% of the recommended dose) and four conduction systems, with three replications. Productivity, lycopene content, total soluble solids (TSS), nitrogen, phosphorus, potassium, calcium and magnesium fruit contents were evaluated. The results showed that higher fertilizer doses increased lycopene levels, reaching 80 μg g-1 with 200% fertilization, while 0% provided 30 μg g-1. Total soluble solids above 4°Bx were observed at doses above 150%, regardless of planting density. Nitrogen content reached 26 mg·100 g-1f.m., favored by lower densities. Calcium was influenced by fertilizer doses, with higher concentrations at 150%. In conclusion, the application of 150% fertilizer dose improved the nutritional quality of tomatoes, and the 200% dose provided suitable levels of TSS and lycopene for processing.

Dynamics of the Humus State of Southern Chernozem with Prolonged Use of Mineral Fertilizers in the Conditions of the Steppe Volga Region

The results of monitoring the dynamics of humus and total nitrogen of the southern chernozem in a long-term stationary experiment with the use of mineral fertilizers are presented. In the first 3 rotations of the grain-to-crop rotation, intensive mineralization of humus was noted in all variants of the experiment. In the conditions of grainsteam crop rotation, this process slowed down, and in the variant with the use of minimum doses of nitrogenphosphorus fertilizers in the 6th rotation, the accumulation of humic substances was revealed. The maximum decrease in humus content at the end of 8 rotations of crop rotation (more than 48 years) was observed in variants with the introduction of medium and high doses of nitrogenphosphorus fertilizers. The use of a minimum dose of fertilizers best compensated for the loss of humus of the southern chernozem during prolonged agricultural use. In comparison with the initial data, negative changes in the qualitative composition of humus were noted in the experiment, expressed in a decrease in the proportion of humic acids. At the end of the 8th rotation, the total nitrogen content in the soil decreased in all variants of the experiment.

Efficient removal of lead from polluted paddy soil by one-pot synthesized Nano-Fe3O4 incorporated stable lignin hydrogel

Lead (Pb) contamination in agricultural soils poses a significant threat to both ecosystems and human health. While nano-Fe3O4 exhibits promising potential for Pb remediation, its practical application in the soil is hindered by its’ biotoxicity, easy aggregation, and the risk of secondary pollution. Thus, this study presents a novel approach wherein Fe3O4 was incorporated into hydrogel via a one-pot synthetic strategy (Fe3O4@LH). This incorporation enhanced the mechanical properties and environmental stability of the hydrogel composites. Based on the mechanical properties, environmental stability, and single-point adsorption results for Pb, we selected Fe3O4@LH-4 for further research. The removal mechanism and the feasibility of employing Fe3O4@LH-4 for Pb removal from paddy soil were investigated through batch adsorption experiments and soil culture studies. Results showed that the adsorption process was primarily governed by swelling adsorption, electrostatic adsorption, ion exchange, precipitation, nanometer effect, and complexation mechanisms. The application of Fe3O4@LH-4 significantly led to the reduction of 16.7 %–25.4 % in soil Pb content, with removal rates escalating alongside increased dosage and application periods of Fe3O4@LH-4. Fitting results of the prediction model indicated that the Pb content in mildly Pb-contaminated soil (186.55 mg/kg) would decrease to be below the risk control standard for soil contamination of agricultural land in China (140 mg/kg) after 112 days of continuous application. Concurrently, cadmium and arsenic contents in the soil decreased by 5.2 %–10.8 % and 7.1 %–16.7 %, respectively. Moreover, the application of Fe3O4@LH-4 positively influenced soil nutrient levels, with total nitrogen and soil organic matter content significant increments of 13.6 %–41.0 % and 4.6 %–16.1 %, respectively. Furthermore, Fe3O4@LH-4 recovery exceeded 88.3 % after a 90-day application period. These findings underscore the potential of Fe3O4 incorporated hydrogel as a promising agent for the sustained removal of heavy metal Pb from paddy soil.

Mapping Soil-crop Nutrient Dynamics in Continuous Cotton Cultivation Areas of Sangareddy District, Telangana

A soil-crop nutrient survey was conducted in Sangareddy district, Telangana during Rabi, 2023 to study the fertility status of cotton growing soils at 0-15 cm and 15-30 cm depth. Georeferenced soil and leaf samples were collected from 112 sites covering 23 mandals during flowering stage. Soil physical and physico-chemical properties and cotton leaf nutrient content were analysed. In the study area, bulk density, sand, silt and clay content ranged from 1.36-1.66 Mg m-3, 41.84-78.02 %, 6.74-29.60 % and 10.76-42.76 %, respectively. The soils were strongly acidic to slightly alkaline in reaction (4.25-7.98; 4.44-7.97), non-saline (0.026-0.254 dS m-1; 0.020-0.241 dS m-1) and low to high in organic carbon (2.03 to 11.52 g kg-1; 1.13 to 8.24 g kg-1) at 0-15 cm and 15-30 cm depths, respectively. Soil Nutrient Status: Available nitrogen, phosphorus, potassium and exchangeable magnesium contents ranged from 101 to 448 kg ha-1, 7 to 41 kg ha-1, and 154 to 763 kg ha-1 at 0-15 cm depth, respectively while 91 to 319 kg ha-1, 4 to 39 kg ha-1, and 142 to 730 kg ha-1 at 15-30 cm depth, respectively. Crop Nutrient Status: Total nitrogen, phosphorus, potassium and magnesium contents in the collected cotton leaves ranged from 0.53 to 3.64 %, 0.12 to 0.68 %, 0.80 to 1.84 % and 0.27 to 0.92 %, respectively. Soil Fertility Mapping: Soil fertility maps were prepared considering the low/deficient, medium and high/sufficient range of soil macronutrients (N, P, K and Mg) at the depth of 0-15 cm under QGIS 3.36.1. Soil fertility maps showed that soils of the study area were mostly low in available nitrogen, medium in available phosphorus, high in available potassium and sufficient in exchangeable magnesium. Regular soil testing is crucial to monitor the variations in nutrient levels and formulation of appropriate management strategies to address it.

Mixed planting of subtropical Chinese fir in South China improves microbial carbon source metabolism and functional diversity through the accumulation of nutrients from soil aggregates.

Soil microbial functional traits are key indicators of soil microbial ecological traits; however, how mixing patterns of Chinese fir and broadleaved trees drive soil microbial functional trait variation at the aggregate scale and how soil microbial functional traits are linked to soil fertility factors have largely not been determined. In this study, soil from the 0-20 cm depths in three Chinese fir plantations was collected, and the soil samples were separated into >2 mm (large macro-aggregate), 0.25-2 mm (macro-aggregate) and <0.25 mm (micro-aggregate) by complying with an optimal moisture sieving procedure. The metabolic activities, functional diversity and different carbon sources utilization characteristics of the soil microorganisms were determined by the Biolog Eco microplate method. In all Chinese fir plantations, micro-aggregates (<0.25 mm) consistently exhibited the highest levels of microbial metabolic activity, a more uniform carbon source utilisation capacity, and the highest microbial diversity. Micro-aggregates also showed elevated levels of soil organic carbon (OC), total nitrogen (TN), total phosphorus (TP), and higher ratios of C/N and C/P compared to large macro-aggregates and macro-aggregates, indicating that micro-aggregates contain more resources available to soil microorganisms. Soil OC, TN, and TP content were enhanced by integration with Michelia macclurei, suggesting that this combination promotes relatively favourable soil conditions for microbial growth and multiplication. This, in turn, promotes microbial metabolic activity. Furthermore, redundancy and correlation analyses showed that soil OC, TN, and TP were identified as principal determinants of soil microbial functional properties in Chinese fir plantations. In summary, mixed cultivation and aggregate size influenced microbial functional properties via soil nutrient alterations. Consequently, adopting a mixed cultivation approach of Chinese fir and broadleaved trees is advocated in the subtropical regions of Guangxi. Employing a diversity of tree species, including M. macclurei, is recommended for optimal soil quality preservation.

Environmental and energy efficiency of a selected municipal wastewater treatment plant – a case study

Based on the analysis of environmental and energy efficiency in the years 2019–2021 in the selected sewage treatment plant (WWT) located in the southern Poland with mechanical-biological wastewater treatment, it was found that the highest level of pollution reduction of 98% enabled the highest BOD5 concentration to be reduced more than 800 times. The operation of the sewage treatment plant was characterized by variable efficiency of the treatment process, which was demonstrated by significant differences in chemical indicators (BOD5, COD, P, TSS and N). Low average concentration of total nitrogen below 4 mg l−1 occurred with a reduction of pollutants at a level not exceeding 90%. Noticeable energy consumption of 1.58 kWh m−3 related to the increase in the amount of treated sewage, confirmed by a moderate correlation, indicated the need to optimize the treatment process.

A fascinating exploration into nitrite accumulation into low concentration reactors using cutting-edge machine learning techniques

In the last couple decades, more use of nitrogenous chemical fertilizers and improper disposable of wastewater has harmed water and it cause water pollution. Low concentrated Nitrite (NO2) is the one of hazardous pollution and it is difficult to remove through biological processes, while it occurs in low concentration. Many technologies have been developed to accumulate NO2 in the mainstream. However, most of them use chemical inhibitors for nitrite oxidizing bacteria (NOB). In past studies high concentrated reactor performance have been modeled using mathematical models. In this study, machine learning application (MLA) was applied to model the performance of reactors. The reactor was low concentrated, continuous stirred tank reactor (CSTR) with in-fluent total ammonia nitrogen (TAN) concentration was (∼30PPM-TAN and ∼50PPM-TAN) and lower output TAN concentration was (∼1PPM-TAN). However, 216 days of water treatment data from CSTR were used, and the CSTR’s efficiency (%) of nitrite accumulation was estimated using in-fluent and effluent quantities. Then efficiency is predicted with 70 % of the data that is used to train the algorithms. Confusion matrix was used to access the performance of algorithms and actual and predicted classes (efficiencies) were compared. The DTC and XGB over-performed other algorithms.

Growth and Yield Dynamics in Three Japanese Soybean Cultivars with Plant Growth-Promoting Pseudomonas spp. and Bradyrhizobium ottawaense Co-Inoculation.

Co-inoculation of soybeans with Bradyrhizobium and plant growth-promoting bacteria has displayed promise for enhancing plant growth, but concrete evidence of its impact on soybean yields is limited. Therefore, this study assessed the comparative efficacy of two 1-aminocyclopropane-1-carboxylate deaminase-producing Pseudomonas species (OFT2 and OFT5) co-inoculated with Bradyrhizobium ottawaense (SG09) on the growth, physiology, nodulation efficiency, and grain yield of three major Japanese soybean cultivars: Enrei, Fukuyutaka, and Satonohohoemi. The experiments were conducted in a warehouse under natural light conditions. The treatments included the inoculation of SG09, SG09 + OFT2, and SG09 + OFT5. Compared with Bradyrhizobium inoculation alone, co-inoculation led to significant improvements in nodulation efficiency, growth, and physiological performance in the Enrei and Fukuyutaka cultivars, but not in the Satonohohoemi cultivar. Furthermore, co-inoculation significantly boosted the total nitrogen content and ion uptake in the shoots, ultimately leading to a remarkable improvement in the grain yield in the Enrei and Fukuyutaka cultivars. These findings contribute to clarifying the interplay among Bradyrhizobium, Pseudomonas, and the plant host cultivar. Notably, Bradyrhizobium-Pseudomonas co-inoculation represents a potentially effective biofertilization strategy for soybean production, highlighting promising avenues for sustainable agricultural practices.

Hydrothermal carbonisation of manure-derived digestates: Chemical properties and heavy metals distribution in end-products

Hydrothermal carbonisation (HTC) presents a promising method for converting high-moisture biomass into hydrochars, which can serve as valuable sources of carbon and nutrients for soil applications. However, there is a lack of comprehensive understanding regarding the characterisation and potential environmental risks of hydrochars with respect to different feedstock types and operating conditions especially when compared to those obtained from dry pyrolysis. This research aims to investigate the chemical properties and re-partitioning of Ni, Cd, Cr and Pb in the HTC-treated mono-and co-digestates derived from the anaerobic digestion of pig manure and ensiled maize. Hydrochars were produced from homogeneous digestate slurries, where manure was derived from a unique source separation facility, and maize was collected from a contaminated land, both containing potentially higher concentrations of heavy metals (HMs) compared to typical feedstock. The hypothesis states that HTC would further reduce the potential availability of these metals, enhancing the quality of the end-products as bio-based fertilisers or soil improvers. The derived hydrochars were analysed for their composition and HMs extractability. Higher yields were observed for both digestates at lower temperatures and shorter residence times, whereas the total nitrogen and carbon content showed an opposite trend. The composition of the digestates and the HTC operating parameters influenced the enrichment of nutrients and release of the HMs from the hydrochars, enabling their classification as potential solid organic fertilisers according to the Fertilising Products Regulation (EU) 2019/1009. Notably, the HTC treatment at 200–220 °C for 4 h resulted in the highest immobilization of Ni, Cd, Cr, and Pb in both digestates. This treatment strategy effectively reduced the ecological risk index of these products, thereby mitigating potential environmental impacts associated with the HMs contamination.

Variability of soil enzyme activities and nutrients with forest gap renewal interacting with soil depths in degraded karst forests

Forest gaps serve as crucial starting points for forest self-renewal. Within these gaps, soil enzymes play an essential role in driving nutrient transformation and species renewal. However, how forest gap renewal regulates soil fertility through soil enzyme across various soil depths remains unclear. This investigation delved into the dynamics of soil enzymes and nutrients within karst forest gaps at four developmental age stages: Infancy (<10 years), Youth (10–20 years), Middlescence (20–30 years), and Elder (>30 years) across different soil depths (0–10 cm, 10–20 cm, and 20–30 cm). The study determined the contents of CNP and the activities of soil enzymes such as polyphenol oxidase, catalase, protease, and alkaline phosphatase. Two-way ANOVA was employed to assess the variations in gap ages and soil depths, along with their interaction. Redundancy analysis (RDA) was used to reveal the correlations between soil enzyme activities and CNP fertility indicators. The results indicated that gap age significantly influenced the activities of alkaline phosphatase, polyphenol oxidase, and protease, as well as the contents of total and available nitrogen, phosphorus, and organic carbon, alongside the ratios of N/P, C/N, and C/P. Catalase activity, however, did not vary significantly with gap age, although soil depth influenced these parameters, excluding total phosphorus and the C/N ratio. Notably, in the 0–10 cm soil layer, alkaline phosphatase activity, total nitrogen, available nitrogen, and organic carbon contents significantly increased with gap age increase, followed by a significant decrease after the middlescence stage. In the 10–20 cm and 20–30 cm soil layers, Alkaline phosphatase and polyphenol oxidase activities, along with N/P and C/N ratios initially decreased and then increased with gap age increase. During the Infancy, Youth, and Middlescence stages, Polyphenol oxidase and protease activities, CNP contents, as well as N/P and C/P ratios generally decreased with soil depth increase or after an increase in the 10–20 cm soil layer. RDA highlighted the variational positive and negative correlations between soil enzyme activities and CNP fertility indicators across soil depths during forest gap renewal, with explanatory rates ranging from 88.05 % to 94.67 % across soil layers. Overall, this study suggests that forest gap renewal significantly influences soil enzymes, CNP content and stoichiometry, modifying soil CNP content through stoichiometric regulation across different soil depths, and ultimately sustaining soil fertility via soil enzymes.

Elemental composition of &lt;i&gt;Vaccinium vitis-idaea&lt;/i&gt; и &lt;i&gt;V. myrtillus&lt;/i&gt; (Ercaceae) leaves in green moss pine forests under aerotechnogenic pollution in the Komi Republic

The paper aims at the impact of aerotechnogenic emissions from the largest in the European North pulp and paper production enterprise, namely JSC «Syktyvkar Timber Processing Complex», on the elemental composition (N, S, C, P, K, Ca, Mg, Na, Al, Fe, Mn) of lingonberry and blueberry leaves as the dominant dwarf shrubs in green moss pine forests. The leaves of blueberry and lingonberry growing in pine stands both in the background and contaminated areas were identified to have similar average values of the mass fraction of ash elements in 2009. The content of ash elements in the leaves of dwarf shrubs from the background pine forests was higher than that in leaves collected from the impact zone in 2018. The average values of the mass fraction of ash elements in blueberry leaves were found to access those in lingonberry leaves by 1,5 time both in the background and contaminated areas. There was no regular change in the content of elements in leaves of dwarf shrubs with distance from the source of emission. The differences in the sulfur content in leaves of dwarf shrubs for 2009 and 2018 were within the error limits. No significant differences were found in the values of the mass fraction of nitrogen in blueberry and lingonberry leaves for pine stands located at different distances from the emission source. The nitrogen content in lingonberry leaves was significantly lower than that in blueberry leaves for both observation periods. There was no significant difference in the total nitrogen content in blueberry and lingonberry leaves between 2009 and 2018.

Performances of full-scale biological nitrogen pre-treatment process for drinking water source: Seasonal variations and microbial community

This study investigated the performance of the full-scale unit over a two-year period to enhance nitrification efficiency and provide operational strategies. Results indicated that raw water quality from Donggan River was notably influenced by seasonal variations, particularly during dry and wet seasons, impacting the nitrification efficiency of the biological pretreatment process. Factors such as influent concentrations of ammonia and total Kjeldahl nitrogen were found to have significant effects on nitrification, with temperature and conductivity also showing correlations. The specific rate of ammonia removal was calculated to be approximately 0.1 kg-N/m3/d under the existing operational setup. Moreover, elevating dissolved oxygen levels above 4 mg/L was proposed to potentially boost ammonia oxidation based on findings from experiments conducted in lab-scale bioreactors. In times of increased influent ammonia levels, the elimination of about 1–3 mg-N/L of total nitrogen signified the activation of denitrification processes. This observation was corroborated by results from next-generation sequencing techniques, verifying the existence of denitrifying microorganisms. The real-time PCR analysis results indicated that the abundance of comammox amoA gene was comparable with the abundance of the AOB amoA gene, indicating the presence of comammox Nitrospira and their potential role on nitrification in the system.

Effects of Land Use Change on Soil Aggregate Stability and Erodibility in the Karst Region of Southwest China

Differences in land use type and chronological age affect soil properties and plant community characteristics, which may influence soil structural stability and erodibility. However, knowledge on the effects of soil physicochemical properties on soil aggregate stability and erodibility at different land use years is limited. This study selected five land use types: corn field (Year 38th-y), corn intercropped with cabbage field (Year 38th-y + b), fruit and meridian forest (Year 6th-jgl), naturally restored vegetation (Year 6th-zr), and artificial forest (Year 7th-rgl) in the karst landscape of the Chishui River Basin in Yunnan Province. We aimed to identify the influencing factors of soil stability and erodibility under different land use time series. The results indicated that the mean weight diameter (MWD), the geometric mean diameter (GMD), and soil structural stability index (SSI values) were highest in Y6th-zr and lowest in Y7th-rgl. Conversely, the erodibility K value was lowest in Y6th-zr, suggesting that the soil structure in Y6th-zr exhibited greater stability, whereas soil stability in Y7th-rgl was lower. Redundancy and throughput analyses revealed that organic carbon and water-stable aggregates &gt; 2.0 mm content had higher vector values. Soil bulk density, total nitrogen, organic carbon, and soil texture content were the main factors contributing to soil stability variation (0.338–0.646). Additionally, total nitrogen, organic carbon, total phosphorus, and soil texture content drove the variation in K values (0.15–1.311). Natural vegetation restoration measures can enhance soil structure to a certain extent. These findings highlight changes in soil aggregate stability and erodibility over different land use durations. The research results have important theoretical and practical significance for understanding the differences in soil erosion and soil restoration under different land use patterns in the karst landscapes of southwest China.