High Organic Matter Content Research Articles

Effect of Biochar on Composting of Cow Manure and Kitchen Waste

Composting is a common method for managing organic waste and creating nutrient-rich soil amendments. Recently, biochar, a carbon-rich material from biomass pyrolysis, has been noted for potentially improving composting. This study examines the impact of adding biochar to compost made from cow manure and kitchen waste through a controlled lab experiment. The treatments were labeled as CMX (cow manure), KWX (kitchen waste), and CMKWX (both) with X being the percentage of CM, KW, and CMKW minus that of biochar in the mixture. Key parameters such as temperature (T), pH, and electric conductivity (EC) were tracked during the composting processes, and the final composts were analyzed for total nitrogen (N), available nitrogen (AN), total phosphorus (TP), available phosphorus (AP), total potassium (TK), organic carbon (OC), calcium (Ca2+), magnesium (Mg2+), and organic matter (OM). The results showed that adding less than 10% biochar influenced composting positively. Specifically, 5% biochar amendment led to higher thermophilic temperatures (45–57 °C) and stable pH levels (6.3–8.7) compared to controls. However, biochar did not significantly enhance EC, which peaked at 1.78 dS/m in both the control and 5% biochar treatments. Nutrient analysis revealed that biochar increased Ca2+ (13.62 meq/g) and Mg2+ (5.73 meq/g) retention in CM composts (CM85 and CM100). The highest OM content was 16.84% in CM90, while the lowest was 3.81% in CM95. Higher OM negatively affected TN, with CM treatments having more OM and KW treatments having more TN. TP and TK were higher in control treatments without biochar. This study highlights the benefits of integrating biochar with organic waste for enhancing compost nutrient profiles and soil fertility. It was observed that the more diverse the compost feedstock, i.e., CMKW, the higher the nutrient content for treatments containing less than 10% biochar.

The role of environment descriptors and seagrass biometrics in shaping macrobenthic assemblages’ structure in intertidal Zostera noltei meadows

The present study describes macroinvertebrate assemblages in three Zostera noltei meadows, following a salinity gradient along the Aveiro lagoon (Portugal). The main environmental descriptors and Z. noltei biometrics were studied to provide a model of the multivariate macroinvertebrate assemblage structure. The macroinvertebrate assemblage structure in the meadow close to the lagoon opening was significantly different. This could be explained by its higher organic matter content and salinity values. Our model highlighted that 72% of the variation on macroinvertebrate assemblage structure was explained by the studied variables, being organic matter, salinity and sediment median grain size the most relevant factors. Moreover, the number of Z. noltei shoots, and cover of the invasive species Agarophyton aff. vermiculophyllum were also significant. The strong relationship between macroinvertebrates, environmental descriptors and Z. noltei biometrics validates the usefulness of macroinvertebrates as indicators of the seagrass condition in intertidal environments. This study provides baseline data that will be crucial to detect anthropogenic disturbances and preserve Z. noltei meadows, including their associated biodiversity. These data will also allow focusing on certain environmental factors and Z. noltei biometrics that have proved shaping the macroinvertebrate assemblages’ structure.

Paleoenvironmental Transition during the Rhuddanian–Aeronian and Its Implications for Lithofacies Evolution and Shale Gas Exploration: Insights from the Changning Area, Southern Sichuan Basin, South-West China

During the Rhuddanian–Aeronian interglacial period, global geological events such as glacial melting, synsedimentary volcanic activity, biological resurgence, and large-scale marine transgressions caused frequent fluctuations in paleoproductivity, climate changes, and sea level variations. These paleoenvironmental transitions directly influenced the development characteristics of shale lithofacies. This study investigates the Longmaxi Formation shale in the Changning area in the Southern Sichuan basin, focusing on 28 core samples from Well N1. Using scanning electron microscopy, QEMSCAN, TOC, XRD, and major and trace element analyses, we reconstructed the paleoenvironmental transitions of this period and explored their control over shale lithofacies types and mineral compositions. Four shale lithofacies were identified: carbonate rich lithofacies (CRF), biogenic quartz-rich lithofacies (BQRF), detrital clay-rich lithofacies (CRDF), and detrital quartz-rich lithofacies (DQRF). During the Rhuddanian period, rising global temperatures caused glacial melting and rapid marine transgressions. The low oxygen levels in bottom waters, combined with upwelling and abundant volcanic material, led to high paleoproductivity. This period primarily developed BQRF and CRF. Rich nutrients and abundant siliceous organisms, along with anoxic to anaerobic conditions, provided the material basis and preservation conditions for high biogenic quartz and organic matter content. High paleoproductivity and anoxic conditions also facilitated the precipitation of synsedimentary calcite and supplied Mg2+ and SO42− for the formation of iron-poor dolomite via sulfate reduction. From the Late Rhuddanian to the Mid-Aeronian, the Guangxi orogeny caused sea levels to fall, increasing water oxidation and reducing upwelling and volcanic activity, which lowered paleoproductivity. Rapid sedimentation rates, stepwise global temperature increases, and the intermittent intensification of weathering affected terrigenous clastic input, resulting in the alternating deposition of CRF, CRDF, and DQRF. Two favorable shale gas reservoirs were identified from the Rhuddanian–Aeronian period: Type I (BQRF) in the L1–L3 Layers, characterized by high TOC and brittleness, and Type II (DQRF) in the L4 Layer, with significant detrital quartz content. The Type I-favorable reservoir supports ongoing gas production, and the Type II-favorable reservoir offers potential as a future exploration target.

The effects and mechanism of organic matter degradation in river sediment driven by humic-reducing bacteria

The reduction of organic pollutants in sediments is essential for controlling the rebound of black-odor waterbodies. Humic-reducing bacteria are promising in the anaerobic remediation of river sediments. However, the material conditions and environmental factors influencing organic matter (OM) degraded by humic-reducing bacteria in river sediment remain unclear. In this study, humic-reducing bacteria agents (HRBs) were used to remediate sediments with different contamination levels. The result indicated that HRBs remove light fraction organic matter (LFOM) in sediment with a high active organic matter (ATOM) content and can remove heavy fraction organic matter (HFOM) in sediment with a high degree of humification. Correlation analysis showed that OM removal was significantly correlated with fluorescein diacetate (FDA) hydrolase activity (R = 0.89, P ≤ 0.01) and acidified volatile sulfides (AVS) content (R = 0.81, P ≤ 0.05), respectively. Combined analyses of changes in iron morphology and FDA hydrolase activity revealed that HRBs mediated the reduction process of iron minerals, leading to an increase in Fe(II) content in sediment. HFOM complexed with iron minerals was released and could be further decomposed and utilized by FDA hydrolases. In addition, the process of OM degraded by HRBs can induce the accumulation of Fe(II) and AVS. The work helps to understand the mechanism of OM degraded by HRBs in sediment and the applicable conditions for the effective removal of OM by HRBs to control the rebound of black-odor waterbodies caused by endogenous pollution.

The Valorization of Fruit and Vegetable Wastes Using an Anaerobic Fixed Biofilm Reactor: A Case of Discarded Tomatoes from a Traditional Market

Tomato waste, characterized by high organic matter and moisture content, offers a promising substrate for anaerobic digestion, though rapid acidification can inhibit methanogenic activity. This study investigated the performance of a 10.25 L anaerobic fixed biofilm reactor for biogas production using liquid tomato waste, processed through grinding and filtration, at high organic loading rates, without external pH control or co-digestion. Four scouring pads were vertically installed as a fixed bed within a fiberglass structure. Reactor performance and buffering capacity were assessed over three stages with progressively increasing organic loading rates (3.2, 4.35, and 6.26 gCOD/L·d). Methane yields of 0.419 LCH4/gCOD and 0.563 LCH4/g VS were achieved during the kinetic study following stabilization. Biogas production rates reached 1586 mL/h, 1804 mL/h, and 4117 mL/h across the three stages, with methane contents of 69%, 65%, and 72.3%, respectively. Partial alkalinity fluctuated, starting above 1500 mg CaCO3/L in Stage 1, dropping below 500 mg CaCO3/L in Stage 2, and surpassing 3000 mg CaCO3/L in Stage 3. Despite periods of forced acidification, the system demonstrated significant resilience and high buffering capacity, maintaining stability through hydraulic retention time adjustments without the need for external pH regulation. The key stability indicators identified include partial alkalinity, effluent chemical oxygen demand, pH, and one-day cumulative biogas. This study highlights the effectiveness of anaerobic fixed biofilm reactors in treating tomato waste and similar fruit and vegetable residues for sustainable biogas production.

Treatment of bio-treated coking wastewater in a 3DEF system with Fe-loaded needle coke particle electrodes

As one of the most representative hard-to-biodegrade industrial wastewater, coking wastewater is poor in biodegradability and has a high concentration of organic matter. Consequently, even after treatment using biochemical technology, the discharge standards cannot be reached. We used the self-developed Fe-loaded needle coke electrodes (Fe-NCPEs) as particle electrodes and established a three-dimensional electro-Fenton (3DEF) system for the treatment of bio-treated coking wastewater (BTCW) in this study. The 3DEF system's conditions for treating BTCW were optimized using Response Surface Method (RSM). When the initial pH was 4.69, the applied voltage was 11.1 V, the Fe-NCPE dosage was 11.63 g L−1, and the COD was reduced from 387 to 57.3 mg L−1 and the colour removal rate reached 99 % after 3 h of reaction, meeting local coking wastewater discharge standards. The power consumption is only 15 kWh per ton of BTCW, indicating that this system can treat the BTCW with high efficiency and low energy consumption. UV-Vis, FTIR, and GC-MS analysis illustrated that cyclic aromatic compounds, esters, and ethers can be efficiently degraded to alkanes and olefins by the 3DEF system. The ·OH quenching experiments showed that in the 3DEF system, the ·OH is the main reactive group, which can oxidize the large hard-to-degrade organic compounds in BTCW to small organic compounds, and even to CO2 and H2O. Dynamic experiments showed that the 3DEF system can successfully remove pollutants from BTCW under continuous flow conditions with an HRT of 3 h, allowing it to meet emission standards.

Rhizobacterial diversity of Portuguese olive cultivars in the Douro valley and their potential as plant growth promoters.

This study investigated the bacterial communities in the rhizosphere of two traditional Portuguese olive cultivars, Cobrançosa and Negrinha de Freixo, in relation to soil properties. Additionally, we aimed to isolate and identify bacteria with potential for biocontrol and other plant growth-promoting traits from these rhizosphere communities. Bacterial communities in the olive rhizosphere were investigated using a metabarcoding approach and the soil physicochemical properties of the olive groves were also analyzed. Higher bacterial richness was associated with Negrinha de Freixo growing in soil with high organic matter content and water-holding capacity. In contrast, the soils of the Cobrançosa grove presented higher pH and electric conductivity. Negrinha de Freixo rhizosphere was enriched with ASVs (Amplicon Sequence Variants) belonging to Bacillus, Gaiella, Acidothermus, Bradyrhizobium, and uncultured Xanthobacteraceae. On the other hand, the Cobrançosa rhizosphere was characterized by higher relative abundance of Streptomyces and Sphingomonas. Bacterial isolation from the rhizosphere and screening for plant growth-promoting activities were also performed. Six bacteria strains, predominantly Bacillus isolated from Negrinha de Freixo, demonstrated antagonistic activities against the olive fungal pathogen Colletotrichum gloeosporoides and other plant growth promotion (PGP) traits. Our findings demonstrate that the structure of rhizosphere bacterial communities associated with olive trees is shaped by both plant cultivar and soil-related factors. The higher number of bacterial species in the rhizosphere of Negrinha de Freixo was related to a higher organic matter content and a greater abundance of isolates with plant growth promotion traits, particularly Bacillus strains.

Analysis of dissolved organic matter characteristics in pharmaceutical wastewater via spectroscopy combined with Fourier-transform ion cyclotron resonance mass spectrometry

Studying the changes in organic matter and characteristic pollutants during the treatment of penicillin-containing pharmaceutical wastewater, which can be reflected by changes in dissolved organic matter (DOM), is crucial for improving the effectiveness of wastewater treatment units and systems. Herein, water quality indicators, spectroscopic methods, and Fourier-transform ion cyclotron resonance mass spectrometry were utilized to characterize the general molecular compositions and specific molecular changes in DOM during the treatment of typical penicillin-containing pharmaceutical wastewater, including in each of the influent, physicochemical treatment, biological treatment, oxidation treatment, and effluent stages. The influent exhibited a high organic matter content (concentration of dissolved organic carbon >10,000 mg·L−1), its DOM mainly contained protein- and lignin-like substances composed of CHON and CHONS molecules, and the relative intensity (RI) of penicillin was extremely high (RI = 0.220). Compared with the influent, the abundance of CHON and CHONS molecules detected after physicochemical treatment decreased by 70.3 % and 62.5 %, respectively, and the RI of penicillin decreased by 85.5 %. Biological treatment caused substantial changes in DOM components through oxidation, dealkylation, and denitrification reactions, accounting for 36.8 %, 28.9 %, and 14.8 % of the total identified reactions, respectively. Additionally, lignin-like substances were generated in large quantities, the overall humification level significantly increased, and the RI value increased for the penicillin intermediate, 6-aminopenicillanic acid (6-APA). Oxidation treatment effectively removed phosphorus-containing substances and some lignin-like substances produced by biological treatment; however, it was not effective in removing characteristic pollutants such as 6-APA. Such characteristic substances continued to be present in the effluent, and the DOM mainly contained protein- and humus-like substances, accounting for 30.8 % and 47.3 %, respectively. The study findings reveal the changes in organic matter and characteristic pollutants during the treatment of penicillin-containing wastewater from the perspective of the general molecular composition and specific molecular changes in DOM, providing support for further exploration of wastewater treatment mechanisms and improvements in treatment unit efficiency.

Quantification of the Few Parameters and Metallic Elements in the Quaternary Sediments of “Baie Du Repos” and their Interrelation

Mauritania is a fishing country. However, the Mauritanian coast is increasingly exposed to environmental issues mainly due to anthropogenic activities such as the mining, gas, oil, and fishing industries, as well as new agricultural practices that unreasonably use inputs. Environmental monitoring of the Mauritanian coast faces several challenges; thus, improving the fisheries sector begins with enhancing the state of marine ecosystems and implementing environmental monitoring adapted to climatic conditions and local needs. This study aims to evaluate the quality of the sediments of the “Baie du Repos” in the town of Nouadhibou, Mauritania, through the study of organic matter and the quantification of trace metallic elements in the Quaternary sediments of the Bay. Six samples deemed representative of this Bay were taken and transported to the laboratory. The physicochemical analysis of these samples shows that the superficial horizons of 30 cm depth have overall organic matter contents higher than the average threshold value proposed by the literature for 4 out of 6 of the points studied. The contents recorded for the different metallic trace elements indicate that point 1 is the most exposed to contamination, with the highest concentrations of cadmium, lead, copper, iron, and zinc. The ACP (Principal Component Analysis) showed that the metallic trace elements Pb, Cu, Fe, Cd, and Zn are closely related and evolve positively in the same direction. Additionally, it was found that the points studied are divided into three groups: Group 1 contains only point 1, which is the most exposed to contamination by these toxic elements (Pb, Cu, Zn, Fe, and Cd). Group 2 contains points 3, 5, and 6, which are moderately contaminated by metallic elements with a significant dominance of organic matter (OM). Finally, Group 3 is the least contaminated, with a very high content of organic matter (OM).

Insight into the impact of environmental factors on heavy metal adsorption by sodium alginate hydrogel: Inspiration on applicable scenarios

Sodium alginate (SA) emerges as a promising adsorbent for the remediation of heavy metal-polluted wastewater. However, the systematic investigations on how and the extent to which the various compositions in real water matrices impact its performance were essential but rare when considering its use. Here, we explored the effect of common environmental factors on Cu(II) adsorption by an as-synthesized SA-based hydrogel (SAH). The result showed that high concentration of organics (above 10 mg L−1) had a negative influence on heavy metal removal (decreased by 9.45 % at least), while inorganic ion, turbidity and antibiotics at relatively low concentrations exhibited a negligible even promoting effect (increased by 9.8 % with the presence of 5 mg L−1 Nor). Based on above results and corresponding mechanism analyses, the possible applicable and unsuitable scenarios of SAH can be predicted. SAH could be a great candidate for treating heavy metal-polluted water such as river and lake water, while it is not a good option for electroplating or livestock wastewater which contains high concentration of organic matters. Besides, the operating conditions including pH (5.0 for Cu(II), 6.0 for Ni(II)), contact time (24 h), temperature (298 K) et al. were also determined. Overall, this work provides theoretical guidance and operational strategies for promoting the practical application of SA adsorbent in water treatment.

Assessing hydrogen production potential from carbonate and shale source rocks: A geochemical investigation

The global push towards achieving net-zero carbon dioxide emissions by 2050 shows the urgency of transitioning to a hydrogen-based economy, with clean hydrogen fuel emerging as a fundamental component of future energy consumption. This study explores hydrogen production from geological sources, specifically organic-rich Shale and Carbonate mudrocks, as a significant and sustainable method for natural hydrogen production. Recognizing the critical challenge posed by the interaction of hydrogen with rock-forming minerals and organic matter during production, this research emphasizes the need for a comprehensive understanding of the geochemical composition of these rock materials. To assess the feasibility and implications of utilizing organic-rich source rocks for hydrogen production, we conducted thorough analyses of source rock samples from different formations. The representatives’ samples were subjected to comprehensive analyses including Rock-Eval pyrolysis, X-ray diffraction (XRD), X-ray fluorescence (XRF), scanning electron microscope (SEM) examinations, and gas chromatography (GC) analysis of the produced gas. Our results revealed that the high total organic carbon (TOC) samples (average 14.7 %) with Type I and II kerogens yielded substantial hydrogen-rich gases, approximately 44.71 % and 36.02 % for SH-O1 and JOS samples, respectively. JOS produced slightly higher hydrocarbon gases (∼50 %) compared to SH-O1 (∼45 %), along with more H2S (5.78 %), due to higher total sulfur content. In contrast, the SH-C1 sample, characterized by very low TOC (0.27 %), predominantly quartz and muscovite minerals (>78 %), and Type IV kerogen, produced higher CO2 (22.09 %) and minimal hydrogen (1.27 %), highlighting the influence of mineralogical and geochemical composition. This study suggests that hydrocarbon source rocks with high organic matter content hold significant potential for maximizing energy gas recovery (>85 %, including hydrogen and hydrocarbons) through the pyrolysis of their kerogen content. These findings demonstrate the viability of hydrogen gas production from unconventional sources such as organic-rich shales, potentially impacting strategies for sustainable energy production and contributing significantly to global decarbonization efforts.

Assessment of the Biochemical Methane Potential of Wastewater and Sludge Cake from a Poultry Slaughterhouse

Objectives : This study evaluates the potential for resource recovery through anaerobic digestion of organic waste generated in a poultry slaughterhouse, specifically focusing on poultry slaughterhouse wastewater and sludge cake obtained from in-house wastewater treatment.Methods : Basic characteristics (total solids, alkalinity, etc.), total nitrogen/ammonia nitrogen, and elemental analysis (macro and trace elements) were performed to determine the properties of the samples and calculate theoretical methane potential. Experimental methane potential was determined through BMP tests, with parameters such as lag period (λ) and maximum methane production rate (CH 4 mL/g VS/d) obtained using the modified Gompertz equation.Results and Discussion : The wastewater exhibited low organic matter concentration (1.79 g VS/kg; 3.74 g COD/L), while the sludge cake showed high total solids content (TS 170.8 g/kg) and organic matter concentration (131.5 g VS/kg; 220 g COD/L). Elemental analysis revealed that the C/N ratio was 9.17 for the sludge cake and 8.24 for the wastewater, indicating high nitrogen content. Methane production modeling using the modified Gompertz equation revealed a lag period of 7.5 days and T80 (time to produce 80% of total methane) of 21 days for wastewater, and a lag period of 2.4 days and T80 of 14 days for sludge cake.Conclusion : Wastewater and sludge cake from poultry slaughterhouses show significant potential as substrates for anaerobic digestion. However, the wastewater has low organic matter content, and the sludge cake, while high in organic matter, has low moisture and high ammonia levels. Therefore, it may be appropriate to co-digest these two substrates, or to co-digest the sludge cake with other substrates that have low nitrogen content and high water content. These findings provide fundamental data for the anaerobic digestion of slaughterhouse waste and highlight the need for further research on co-digestion and continuous processes.

Assessment of the benefits and risks of sewage sludge application as soil amendment for agriculture in Eswatini

Sewage sludge is an important soil conditioner, and source of nutrients with a potential for use in agriculture. However, such benefit needs to be weighed against the risks due to the presence of heavy metals, and other substances that may endanger human health, plants, soil and the ecosystem. This research had the objective of evaluating the agricultural potential of sewage sludge together with the risks that may be present in use. Samples of sewage sludge from seven wastewater treatment plants in Eswatini were analyzed for selected physical and chemical parameters, and heavy metal concentrations using commonly established laboratory procedures. The analysis results indicated that, sludge samples exhibited high organic matter content, cation exchange capacity, macro nutrients such as nitrogen and phosphorus and micro nutrients (trace metal elements) needed for plant growth. Anaerobically digested sludge samples showed higher carbon to nitrogen ratio because of biomass loss in the form of methane and carbon dioxide. The heavy metal concentrations are all within safe limits except the sludge from Matsapha area that had levels of chromium, and nickel above regulatory limits. With respect to their heavy metal contents, most of the sludge samples would qualify as Class A sludge ready to be used as organic fertilizer for agriculture without regular monitoring of heavy metals in the soil to which they are applied. The study results indicated the importance of sewage sludge for their agricultural potential through supplementation of both micro and macro nutrients needed for plant growth, for improving the soil properties such as water holding capacity and permeability, through the increase of organic matter content, and retention of nutrients due to the high cation exchange capacity. All these benefits are realized with sewage sludge being a lower cost alternative to commercial fertilizers. Moreover, the low concentration of heavy metals present in the sludge presents lower risk that may arise in the course of utilizing the sludge as agricultural supplement. Key words: Agriculture, fertilizer, heavy metals, nutrient, sewage, sludge, nitrogen, phosphorous

The Role of a New Stabilizer in Enhancing the Mechanical Performance of Construction Residue Soils.

Urban construction generates significant amounts of construction residue soil. This paper introduces a novel soil stabilizer based on industrial waste to improve its utilization. This stabilizer is primarily composed of blast furnace slag (BFS), steel slag (SS), phosphogypsum (PG), and other additives, which enhance soil strength through physical and chemical processes. This study investigated the mechanical properties of construction residue soil cured with this stabilizer, focusing on the effects of organic matter content (Oo), stabilizer dosage (Oc), and curing age (T) on unconfined compressive strength (UCS). Additionally, water stability and wet-dry cycle tests of the stabilized soil were conducted to assess long-term performance. According to the findings, the UCS increased with the higher stabilizer dosage and longer curing periods but reduced with the higher organic matter content. A stabilizer content of 15-20% is recommended for optimal stabilization efficacy and cost-efficiency in engineering applications. The samples lost their strength when immersed in water. However, adding more stabilizers to the soil can effectively enhance its water stability. Under wet-dry cycle conditions, the UCS initially increased and then decreased, remaining lower than that of samples cured under standard conditions. The findings can provide valuable data for the practical application in construction residual soil stabilization.

Evaluation of soil quality of cultivated lands with classification and regression-based machine learning algorithms optimization under humid environmental condition

In soil science, machine learning algorithms are preferred for pedotransfer functions due to their rapid data acquisition and high prediction accuracy. The current study aims to evaluate the prediction of soil quality in agricultural lands dominated by the humid Black Sea climate using various algorithms. Both classification and regression-based algorithms (Random Forest-RF, Light Gradient Boosting-LGB, Extreme Gradient Boosting-XGBoost, k-nearest neighbors-kNN, Logistic Regression, multilayer perceptron-MLP, Linear Regression-LR and Bayesian Ridge- BR) were used in the method. The comparison of soil maps is also included. Furthermore, the present study evaluates the Grid Search optimization method with K-Fold Cross Validation (K = 5) for both classification and regression-based algorithms. The prediction of soil quality was performed using class-based and regression-based algorithms. As a result of the study, the RF and XGBoost algorithms achieved an approximate accuracy rate of 92 % in the class-based prediction. In regression-based predictions, the most successful algorithms were BR and LR, with an R2 Score of 0.84. The Grid Search optimization method was used to improve the R2 Score, resulting in an increase to 0.90 and 0.88 for BR and LR, respectively. The optimized hyperparameters showed improved performance in predicting the soil quality index. The present study found that Gaussian and Spherical models had the lowest prediction errors in spatial distribution maps. Tree-based algorithms were found to be suitable for class-based prediction of soil quality, while the linear regression method was appropriate for regression predictions. This study is characterized by a rainy climate resulting in acidic soils with high organic matter content. Planning of new studies in different climates and soil properties is recommended.

The Impact of Organic and Chemical Organic Fertilizers on the Efficiency of Cadmium Mobility Reduction by Potassium Hydroxide Modified Biochar

The aim of this study was to investigate the impact of organic and chemical organic fertilizers on the translocation of cadmium in crude oil-contaminated soil treated with potassium hydroxide-modified biochar (KOH-biochar). The soil sample was collected from Chonburi Province. The soil was characterized as moderately acidic sandy loam with relatively low organic matter, medium salinity, medium cation exchange capacity, and high nutrient levels. The concentration of cadmium in the soil fell within the acceptable range for agricultural use. The KOH-biochar exhibited strong alkalinity, a high carbon/nitrogen (C/N) ratio, and an oxygen/carbon (O/C) ratio. Crude oil was slightly acidic, with high organic matter content and low sulfur and cadmium concentrations. The synthetic soil created in this study composed of 5% crude oil, and 100 mg/kg of cadmium. KOH-biochar, organic and chemical organic fertilizers were applied to this synthetic soil. Subsequently, the soil was subjected to extraction with 0.005 M diethylenetriamine pentaacetate (DTPA), and a sequential extraction method was employed to determine six different forms of cadmium in the soil samples. Cadmium concentrations in the extracts were measured using a graphite furnace atomic absorption spectrophotometer. The findings revealed that fertilizers effectively slowed down the movement of cadmium. Fertilizer application led to the transformation of cadmium from unstable forms to more stable forms within the soil. Fertilizer with the highest organic matter content and pH showed the least cadmium mobility. Increased nitrogen and phosphorus content in the fertilizer resulted in slightly higher cadmium mobility within the soil. Conversely, higher potassium content in the fertilizer led to slightly reduced cadmium mobility in the soil.

Understanding soil factors in corrosion and conservation of buried bronze statuettes: insights for preservation strategies

The findings reveal that soil constituents significantly affect the corrosion process. Moisture content and pH promote the formation of corrosion products, while high chloride concentrations accelerate corrosion. Conversely, high organic matter content inhibits corrosion by limiting oxygen diffusion to the metal surface. The effectiveness of conservation treatments, particularly wax or oil-based coatings, varied with soil conditions, showing reduced efficacy in soils with high chloride concentrations. This study underscores the importance of understanding soil constituents for developing effective corrosion and conservation strategies for buried bronze statuettes. The results offer valuable insights for customizing preservation approaches based on soil types. X-ray diffraction (XRD) analysis revealed that mineralogical compositions in soil significantly influence corrosion processes, providing critical insights for effective preservation strategies. pH measurements indicated varying soil acidity and alkalinity levels, crucial in determining corrosion rates and mechanisms, offering essential data for targeted preservation strategies. Additionally, the identification of brochantite and antlerite through Micro-Raman spectroscopy suggests a link to sulfur pollutants from the decomposition of organic matter by sulfate-reducing bacteria, highlighting the potential environmental impact of microbial activity in the soil ecosystem.

Comprehensive insights into phosphorus solubility and organic matter’s impact on black phosphate leaching

The current study introduces groundbreaking insights into how organic matter (OM) of the black phosphate (RB-Ph) uniquely influences phosphorus (P) solubility during acetic acid (AA) leaching, expanding our understanding in this crucial area. To highlight such role, the OM of the RB-Ph was treated separately by different procedures including calcination at 550 ℃/4 h (CB-Ph), 30% hydrogen peroxide (HB-Ph) and intensive grinding to nano-sizes (NB-Ph). The mineralogical, chemical and morphological characteristics of phosphatic and non-phosphatic components of these phosphatic materials were carefully examined pre- and post-treatment via different techniques. The P dissolution of the precursor RB-Ph and its modified derivatives all over the applied experimental parameters traced the following trend: NB-Ph > RB-Ph > CB-Ph > HB-Ph. Intensive grinding to nanoscale resulted in amorphous components with conspicuous OM content (TOC, 0.410%), significantly enhanced P dissolution rate of NB-Ph (730–980 ppm), despite the noticeable reduction in its P2O5 content to 22.34 wt.%. The precursor RB-Ph, thanks to its high OM content (TOC, 0.543%), also displayed a sufficient P dissolution rate (470–750 ppm) compared to the two other modified derivatives, CB-Ph (410–700 ppm) and HB-Ph (130–610 ppm). Such deep and conspicuous impact of OM on P solubility can be tied to their decomposition, releasing not only organic acids but also the adsorbed P by the OM’s surficial binding sites to the solution. Finally, the optimum conditions of P leaching were attained at 2:1 acid/solid (w/w) ratio and 2 h of retention time of all investigated samples.

Rapid characterization of soil horizons for different soil series utilizing Vis-NIR spectral information

The visible-near infrared (Vis-NIR) reflectance technique is a powerful tool, particularly for obtaining faster information about soil texture, organic matter, and calcium carbonate content. However, there is limited research on the characterization of soil horizons using Vis-NIR data in profiles of different soil series. This study investigated the relationship between soil properties and spectral reflectance (Vis-NIR) in eight soil profiles with varying genetic properties from Harran Plain, Türkiye, focusing on variations within profiles (A, B, and C horizons) and across different soil series. A total of 36 soil samples were collected from the A, B, and C horizons, and spectral reflectance was measured along with calcium carbonate, organic matter, and particle size distribution. High variability was observed in calcium carbonate (11.58–52.50%) and organic matter content (0.60–3.71%), reflecting complex soil composition influenced by parent material and land management. Distinct reflectance patterns were observed within profiles, reflecting variations in soil composition. Ap horizons with higher organic matter content often exhibited lower reflectance (visible region). Clay content influenced NIR reflectance, with higher absorption in clay-rich profiles. The Kaynakli series (Fine-loamy, mixed, mesic Typic Calcixerepts) showed differentiation in reflectance between A and B horizons after 700 nm due to horizon formation and clay/carbonate accumulation. Increasing calcium carbonate content in Ck horizons led to higher reflectance compared to other layers. Confirmed that Vis-NIR reflectance could explain a significant portion of the variance in soil properties (A: 87.7%, B: 88.3%, and C: 90.6%). PCA results supported the notion that spectral signatures captured by Vis-NIR reflectance measurements are indicative of inherent differences between A, B, and C horizons. This study contributes to the growing body of knowledge on the application of Vis-NIR spectroscopy for soil assessment and monitoring. However, future research should focus on understanding spectral reflectance variations under diverse soil and environmental conditions.

Role of Source, Mineralogy, and Organic Complexation on Lability and Fe Isotopic Composition of Terrestrial Fe sources to the Gulf of Alaska.

Iron (Fe) is a key trace nutrient supporting marine primary production, and its deposition in the surface ocean can impact multiple biogeochemical cycles. Understanding Fe cycling in the subarctic is key for tracking the fate of particulate-bound sources of oceans in a changing climate. Recently, Fe isotope ratios have been proposed as a potential tool to trace sources of Fe to the marine environment. Here, we investigate the Fe isotopic composition of terrestrial sources of Fe including glacial sediment, loess, volcanic ash, and wildfire aerosols, all from Alaska. Results show that the δ56Fe values of glaciofluvial silt, glacial dissolved load, volcanic ash, and wildfire aerosols fall in a restricted range of δ56Fe values from -0.02 to +0.12‰, in contrast to the broader range of Fe isotopic compositions observed in loess, -0.50 to +0.13‰. The Fe isotopic composition of the dissolved load of glacial meltwater was consistently lighter compared to its particulate counterpart. The 'aging' (exposure to environmental conditions) of volcanic ash did not significantly fractionate the Fe isotopic composition. The Fe isotopic composition of wildfire aerosols collected during an active fire season in Alaska in the summer of 2019 was not significantly fractionated from those of the average upper continental crust composition. We find that the δ56Fe values of loess (<5 μm fraction) were more negative (-0.32 to +0.05‰) with respect to all samples measured here, had the highest proportion of easily reducible Fe (5.9-59.6%), and were correlated with the degree of chemical weathering and organic matter content. Transmission electron spectroscopy measurements indicate an accumulation of amorphous Fe phases in the loess. Our results indicate that Fe isotopes can be related to Fe lability when in the presence of organic matter and that higher organic matter content is associated with a distinctly more negative Fe isotope signature likely due to Fe-organic complexation.