Organic Matter Content Research Articles

Impact of Integrated Nutrient Management on Soil Micronutrients and Organic Matter Dynamics in Maize-mustard Crop Rotation in Himalayan Foothills

Aims: The purpose of this research is to investigate the effects of inorganic fertilizers and organic manures on availability of micronutrients and organic matter in soils of rainfed agriculture in foothills of Himalayas. Place and Duration of Study: Present study was conducted at Advance Centre for Rainfed Agriculture (ACRA), Rakh Dhiansar, Jammu from 2020 to 2022. Methodology: In a long-term field experiment, we investigated the effects of 10 treatments on soil micronutrients, organic matter and their correlation under rain fed agriculture. Randomized block design was used with three replications. Following are the treatments: T1 - Control, T2 - 100% RDF of N,P,K through chemicals, T3 - 50% RDF of N,P,K through chemicals, T4- 50% RD of N through crop residue, T5 - 50% RD of N through FYM, T6 -50% RDF of N,P,K through chemicals + 50% RDF of N through crop residues, T7- 50% RDF of N,P,K through chemicals + 50% RD of N through FYM, T8 - FYM @ 10 ton/ha, T9 - 100% RDF of N,P,K through chemicals + Zinc Sulphate @ 20kg/ha and T10 - Farmer practice (FYM @ 4 ton/ha + 40kg urea /ha). The micronutrients (Fe, Zn, Cu and Mn) showed maximum increase with the application of organic manures along with inorganic fertilizers over control in both surface and sub surface layers of the soil. However, in the sub-surface soil, there was less availability of these nutrients than the surface layer of the soil. The available Zn content was found maximum in the treatment T9 getting 100% NPK + ZnSO4 @ 20kg/ha over control. The treatment T8 with the application of FYM @ 10 ton/ha recorded highest content of soil organic matter in surface soil. Positive and significant correlations were observed between soil organic matter and the micronutrient content of the soil. The INM practices proved very beneficial for increasing the sustainability of soil.

Utilization of cement deep mixing pile for soft soil foundation: a malaysian case study

Cement deep mixing piles, as representatives of deep mixing technology, are mature and widely applied. However, effective application cases of cement deep mixing piles are relatively scarce in countries like Malaysia in Southeast Asia. In this paper, the application of cement deep mixing pile reinforcement in Malaysia is presented. Solidifying material was selected for deep mixing piles based on the soil conditions using unconfined compressive strength (UCS) tests. The relationship between the strength of deep mixing piles on-site and soil properties (type, organic matter content, and ion content) was analyzed. And a quality evaluation of the deep mixing piles in the project is conducted based on Kolmogorov-Smirnov (K-S) tests and relevant standards. Results show that fly ash cement is suitable as a solidifying agent for acidic soil layers containing organic matter in the local area. The strength of piles is significantly related to the soil condition. The UCS of cement mixing piles in silty clay and peat soils is smaller than clay. The overall correlation between organic matter content in the soil and UCS is negative, particularly when the organic matter content ranges from 10% to 14%, resulting in a significant drop in UCS. The bilateral significance probability is greater than 0.05 in K-S test, indicating that the UCS results in the projectconform to a normal distribution. Additionally, the evaluation of the overall quality of the mixing piles aligns with the requirements in the Japanese standard “Manual of Deep Mixing Construction Technology for Harbors and Airports” and the Chinese standard “Technical Code for Building Foundation Detection”.

Spatial distribution studies on sedimentary organic matter along the shoreline of Arabian Sea: insights from Kollam, Southwest Coast, India.

The present study was aimed at investigating the source, quality, and quantity of organic matter and labile fraction of biochemical constituents in the surficial sediments of Arabian Sea Shoreline at Kollam, India, which gives an input into the processes associated with the subsurface geochemistry pattern. About 15 surface sediment samples were collected from the five beaches for this study during January 2021. The samples were analyzed for CHN, total organic carbon (TOC), and labile fraction such as carbohydrates (CHO), proteins (PRO), and lipids (LIP). The TOC/TN ratio revealed that the source organic matter (OM) in the samples was primarily of marine origin and autochthonous, except TM3 at Thirumullavaram. Thirumullavaram is a sheltered beach, and it has low hydrodynamic process. The high organic matter content in TM3 (13.9) may be the originated from the terrestrial input. The hierarchical cluster analysis revealed that TM3 indicate that unique character to other stations. Principal component analysis revealed that three components accounted for 78% of the total variance. PC1 variance was associated with carbon-based organic compounds. PC2 was predominantly influenced by CHO and LOM, suggesting that PC2 may encompass variability associated with these nutritional profiles. PC3 was influenced by LIP and LIP/CHO, showing it may be a lipid-related component. The PRO to CHO ratio is < 1, exhibiting old aged organic matter deposited in sediments and the meso-oligotrophic status. The LIP to CHO ratio, recorded as < 1, exhibits the poor quality of energetic (food) OM in sediments. The sediment samples exhibit the following trend CHO > PRO > LIP.

Performance of co-composting Pholiota nameko spent mushroom substrate and pig manure at different proportions: Chemical properties and humification process.

Co-composting is the controlled aerobic degradation of organics, using more than one feedstock. By combining the spent mushroom substrate of Pholiota nameko (SMS) and pig manure (PM), the benefits of each could be used to optimize the composting process and the final product. This study introduced a comprehensive evaluation strategy aimed at identifying the optimal co-composting ratio for these two substrates. A 120-day composting trial was conducted, blending SMS and PM in various ratios to evaluate the benefits of co-composting SMS-PM. The results indicated that dissolved organic matter (DOM) in SMS-derived compost primarily originated from plants, whereas PM-derived compost predominantly consisted of microbial metabolic products, and co-composting combined both sources. An increase in aromaticity and humification degree of DOM occurred during the composting process itself rather than being derived from autochthonous origin. Carbohydrates like phenols and alcohols broke down during composting, and microbes utilized polysaccharides as an energy source for humus formation. As co-composting progressed, the treatments with varying mass ratios of SMS to PM, including 8:2, 7:3, 6:4, 5:5, 4:6, and 3:7 were observed to result in a decline in aliphatic hydroxylated chains alongside an enhancement in aromaticity within the compost. Additionally, there was a conversion from organic carbon (C) to carboxyl C within humic acid (HA) due to oxidation and dehydrogenation processes that facilitated the formation of stable nitrogen-containing compounds characterized by condensed aromatic structures. Following thorough evaluation, it was determined that optimal composting efficacy occurred at a mass ratio of SMS to PM equal to 6:4. Post-compost analysis revealed increases in nutrient content; specifically, germination index (GI) value reached 132.7%, while organic matter content attained 45.3%. Conversely, electrical conductivity (EC), C contents of water-soluble substances and humin (Cwss and CHu) decreased by approximately 11.8%, 73.4%, and 29.8% respectively; meanwhile, C contents of humic-extracted acid and HA (CHE and CHA), along with degree of polymerization (DP), increased by 17.3%, 20.3% and 9.9% respectively. The proposed co-compost formula not only facilitated simultaneous recycling of both SMS and PM waste but also transformed them into high-quality organic fertilizers suitable for soil enrichment-effectively addressing challenges faced by both edible fungi cultivation and livestock industries while augmenting organic fertilizer sources for Black land protection.

Carbon fate and potential carbon metabolism effects during in-situ cyanobacterial inhibition by artemisinin sustained-release algaecides.

Carbon pools and microbial carbon metabolism can be significantly altered due to the diverse organic matter properties and low pH characteristics of artemisinin sustained-release algaecides (ASAs). These effects have still not been systematically studied, leading to uncertainty in the application of ASAs for cyanobacterial management in natural waters. This study assessed the effects of ASAs on carbon fate, carbon metabolism and potential ecological impacts during in-situ cyanobacterial inhibition. In the initial phase of ASAs-induced cyanobacterial inhibition (2-10 days), the carbon pool underwent significant changes due to the increased proportion of C4 plant-derived organic matter (97%), humification level (FI =0.9-1.5), and inorganic carbon concentration (TIC = 80-110mg/L). The cyanobacterial apoptosis triggered by ASAs produced particulate organic carbon, which provided a bioavailable carbon source for bacterial metabolism. ASAs enhanced the connection between bacteria and the carbon pool, as well as their carbon metabolism capabilities, by increasing the relative abundance of Proteobacteria (33.1%-37.3%), bacterial diversity, the proportion of Alphaproteobacteria and Betaproteobacteria (19.3%-29.5%) involved in carbon metabolism, and the complexity of the environment-bacteria co-occurrence network. These effects contributed to maintaining long-term ecosystem stability and resistance to cyanobacterial proliferation. Our findings elucidate the influence of bacterial carbon metabolism by ASAs as one of an important mechanism for achieving cyanobacterial inhibition in natural water, and emphasize the important role of bacteria in maintaining ecological stability during in situ cyanobacterial management.

Simulated nitrogen deposition and precipitation events alter microbial carbon cycling during early stages of litter decomposition

Abstract Plant litter decomposition is a major nutrient input to terrestrial ecosystems that is primarily driven by microorganisms. Litter quality is considered a key drive of decomposition; however, human-induced global disturbance like nitrogen deposition and increasing extreme precipitation events will shift nutrient availability during litter decomposition. Little is known about how shifting nutrient availability will impact dissolved organic matter concentrations and microbially driven carbon cycling that are critical to soil organic matter formation. This study investigated the effect of simulated nitrogen deposition and repeated precipitation events on microbially-driven carbon flow during short-term litter decomposition using a ‘common garden’ experiment with microcosms containing sand and blue grama grass litter inoculated with different microbial communities. Overall, nitrogen deposition decoupled respiration and dissolved organic carbon (DOC) by increasing respiration and not affecting DOC concentrations. Moreover, nitrogen deposition had no effect on microbial carbon use efficiency (CUE). Repeated simulated precipitation events significantly increased DOC concentrations, decreased microbial CUE, increased the microbial metabolic quotient (qCO2), and altered microbial composition and diversity. These findings highlight the complex interactions and responses of surface litter decomposers to shifting nutrient availability and contradicts previous findings that nitrogen deposition will increase soil carbon sequestration from a larger supply of DOC and reduced respiration.

Study of the rheological properties and nautical depth assessment of fine sediments in Iranian ports

Sediments containing more than 10% clay particles by mass can exhibit cohesive properties. Cohesive sediments are commonly found in coastal areas worldwide, including the southern shore of the Caspian Sea and the northern/northwestern beaches of the Persian Gulf. These cohesive sediments can form a layer of soft to extremely soft mud, known as fluid mud, covering the seabed. The study examined the properties of natural mud samples collected from different depths and locations within three Iranian ports: Anzali Port (Caspian Sea), and Khorramshahr and Bushehr Ports (Persian Gulf). The laboratory analyses included determining the sediment grain-size distribution, density, carbonate content, organic matter content, and rheological properties at different water content ratios. Disregarding the impact of variations in organic matter and carbonate contents in the samples, water content ratio was the main factor affecting the rheological properties of sediments.

Carbon mineralization potential and nutrient dynamics in soils under vegetation types and soil depths at Luot mountain

Soil mineralization is a crucial soil process that improves soil physical properties, enhances carbon sequestration, and provides essential minerals and available nutrients for plant growth. This study was conducted at five vegetation types and soil depths at Luot mountain area, located in VNUF campus, Hanoi city. Samples were incubated in the dark at 25°C and measured at intervals of 1, 2, 5, 10, 15, 25, 35, and 40 days in the laboratory to determine C-CO2 respiration from soils. The study showed that CO2 emissions were highest in topsoils and decreased with deeper soil depths. Mineralized C-CO2 decreased from Shrubs &gt; Acacia + Native species (NS) &gt; Pinus + NS &gt; Native species &gt; Control. CO2 emissions peaked early in the incubation period and then stabilized in the 40-day incubation period. Larger aggregates (≥ 5mm) decreased significantly under most vegetation types, except for Shrubs, where the reduction was minimal. Aggregate size ≥3mm increased post-incubation, notably under Pinus + NS and Native species, with smaller aggregates also increasing slightly. Organic matter content was highest in the topsoil but decreased post-incubation due to microbial C mineralization. There was an increase in soil organic matter at 10-20 cm and 20-40 cm layers after incubation, especially under Shrubs. Available nitrogen slightly increased in soils post-incubation for most vegetation types. Phosphorus content increased post-incubation, peaking under Shrubs, while potassium levels were generally poor but increased during incubation. The study found that C-CO2 mineralization was strongly associated with soil porosity and pH, suggesting that higher porosity and optimal pH enhance mineralization, with organic matter content being crucial for available nutrient cycles in soils.

Garlic stalk waste and arbuscular mycorrhizae mitigate challenges in continuously monocropping eggplant obstacles by modulating physiochemical properties and fungal community structure.

Continuous vegetable production under plastic tunnels faces challenges like soil degradation, increased soil-borne pathogens, and diminished eggplant yield. These factors collectively threaten the long-term sustainability of food security by diminishing the productivity and resilience of agricultural soils. This research examined the use of raw garlic stalk (RGS) waste and arbuscular mycorrhizal fungi (AMF) as a sustainable solution for these issues in eggplant monoculture. We hypothesized that the combined application of RGS waste and AMF would improve soil physicochemical properties compared to untreated soil in eggplant monoculture. The combined use of RGS and AMF was expected to suppress soil-borne pathogens, increase the abundance of soil beneficial microorganisms and alter fungal community structure. The combined application of RGS and AMF will significantly enhance eggplant yield compared to untreated plots. This study aimed to determine whether AMF and RGS, individually or in combination, can ameliorate the adverse effects of monoculture on eggplant soil. We also investigated whether these treatments could enhance eggplant yield. The experiment was arranged in a completely randomized design with four treatments: AMF, RGS, and a combined treatment of AMF + RGS (ARGS), along with a control. Each treatment was replicated three times, Eggplant seedlings inoculated with AMF and treated with RGS amendments, both individually and combined. The effects on root traits, soil physicochemical properties, soil enzyme activity, and fungal community structure were investigated. RGS amendments and AMF inoculation improved root length, volume, and mycorrhizal colonization. The combined treatment showed the most significant improvement. RGS and AMF application increased soil nutrient availability (N, P, K) and organic matter content. Enzyme activities also increased with RGS and AMF treatments, with the combined application showing the highest activity. Soil electrical conductivity (EC) increased, while soil pH decreased with RGS and AMF amendments. Sequencing revealed a shift in the fungal community structure. Ascomycota abundance decreased, while Basidiomycota abundance increased with RGS and AMF application. The combined treatment reduced the abundance of pathogenic genera (Fusarium) and enriched beneficial taxa (Chaetomium, Coprinellus, Aspergillus). Pearson correlations supported the hypothesis that soil physicochemical properties influence fungal community composition. This study demonstrates the potential of co-applying RGS and AMF in continuous cropping systems. It enhances soil physicochemical properties, reduces soil-borne pathogens, and promotes beneficial microbial communities and eggplant yield. This combined approach offers a sustainable strategy to address the challenges associated with eggplant monoculture under plastic tunnels.

A Systematic Review and Meta-Analysis of the Sustainable Impact of Sewage Sludge Application on Soil Organic Matter and Nutrient Content

The increasing scarcity of natural resources makes the linear production model unsustainable, highlighting the need for more sustainable practices under the umbrella of circular economic principles. Sewage sludge emerges as a promising solution to provide soil organic matter (SOM) and nutrients. This meta-analysis evaluated the impacts of three levels of sludge application (low, medium, and high) on organic matter (OM), nitrogen (N), phosphorus (P), copper (Cu), and zinc (Zn) contents, considering different areas and experimental conditions worldwide. The analysis included 37 studies and 355 comparisons, after screening 7625 records, following the 2020 PRISMA protocol. The effects of sludge concentrations, continents, and types of experiment (field or greenhouse) were evaluated. Sewage sludge application significantly increased OM, N, Cu, and Zn levels, mainly at medium and high rates. The largest effects were observed in greenhouses, suggesting variation by location and environment. Moderators explained a part of the variation in the results, but the residual heterogeneity test revealed that there is still unexplained variability.

Impact of water physicochemical properties on the survival of Oncomelania hupensis snails, the intermediate host of Schistosoma japonicum.

Schistosoma japonicum, the causative agent of schistosomiasis, heavily relies on its single intermediate host, the Oncomelania hupensis snail, for its life cycle. Controlling these snails effectively plays a pivotal role in curbing the transmission and prevalence of this disease. While prior research has extensively investigated the impact of environmental factors such as temperature and vegetation on snail survival, growth, and reproduction, the contribution of water physicochemical properties has been notably underexplored. This study presents laboratory experiments designed to comprehensively explore the influence of water physicochemical properties on snail survival, offering valuable insights into environmental factors for more precise predictions of snail distribution. We meticulously conducted laboratory snail survival experiments using water from different sources (river water/tap water), and employed a statistical approach amalgamating principal component analysis with Cox regression to preliminarily investigate the effects of different water physicochemical properties on the survival of snails. Our analysis indicates that after a 6-month laboratory snail survival experiment, the survival rate in the tap water group was significantly higher than that in the river water group for infected snails (χ2 = 7.74, p = 0.005), while the difference in survival rates for non-infected snails was not statistically significant (χ2 = 0.61, p = 0.434). The Principal Component-Cox regression analysis revealed that in the infected snail group, total phosphorus, pH value, five-day biochemical oxygen demand, conductivity, and nitrite were protective factors for snail survival, while phosphate and total nitrogen were risk factors. In the non-infected snail group, total phosphorus, pH value, five-day biochemical oxygen demand, conductivity, and nitrite were protective factors for snail survival, and total nitrogen, ammonia nitrogen, phosphate, and nitrate were risk factors. This study underscores the substantial impact of water quality's physicochemical properties on snail survival. The effects of water quality on snails are complex, and maintaining an appropriate level of organic matter content and controlling the pH value at a weak alkalescency level prove beneficial for snail survival. These findings hold significant promise for advancing our understanding of snail-borne diseases and optimizing control strategies.

Influence of straw degradation on dredged sludge consolidation under vacuum preloading

Vacuum preloading with straw drainage has been used as an eco-friendly soil-reinforcement method to promote the consolidation of dredged sludge. In previous studies, the degradation of straw, an essential factor influencing dredged-sludge consolidation, has often been disregarded. In this study, laboratory tests were conducted to investigate the effects of straw degradation on the consolidation efficiency of dredged sludge. The vacuum level within the straw drainage decreased with increasing degradation time, causing a reduction in water discharge and settlement. Consequently, the moisture content increased and the shear strength of the soil decreased. After 60 days of degradation, the water discharge and settlement decreased by 46% and 25%, respectively. The impact of degradation time was most significant during the first 15 days, which was when most straw degradation occurred. The average moisture difference from 0-15 days was 5.0%, whereas from 45-60 days it was 0.8%, which was negligible. The increase in the organic matter content enhanced the Atterberg limits and hydrophilic properties of the soil. The findings of this study promote the engineering application of vacuum preloading with straw drainage and confirm it as an effective and eco-friendly method for consolidating dredged sludge.

Research on building a biochar production model from agricultural by-products in Gia Lai province

ABSTRACT The impact of climate change on ecosystems and agricultural systems, particularly in key agricultural areas like the Central Highlands of Vietnam, has caused severe soil degradation, water depletion, and desertification, directly affecting productivity and livelihoods. Sustainable agricultural solutions, especially biochar, have gained attention due to their ability to improve soil fertility, retain moisture, and reduce greenhouse gas emissions. This research focuses on developing a biochar production model from agricultural by-products in Gia Lai to meet both domestic and export needs. Biochar was produced through the pyrolysis of coffee by-products, including stems, branches, and fruit husks. The study employs 10 brick kilns (90 m³ capacity) for stems and branches, and 15 steel kilns (300 kg/batch capacity) for fruit husks and leaves. The biochar produced meets export quality standards, with a fixed carbon content ≥70.0%, ash content ≤3.0%, and calorific value ≥7,000 Kcal/kg. Additionally, biochar is combined with the biological agent Trichoderma to produce 1,000 tons of organic microbial fertilizer, surpassing national standards for organic matter content (≥15%) and Trichoderma density (≥1.0x10⁶ CFU/g). Biochar production from agricultural waste not only reduces waste but also contributes to sustainable agriculture in the Central Highlands. The research results show great potential for expanding biochar production models, improving soil health, reducing farming costs, and increasing farmers' income.

Variability of trace elements in bodies of scrapers (Ephemeroptera) and predators (Plecoptera) from mountain rivers of Dzungarian Alatau (Kazakhstan) and Western Carpathians (Slovakia).

Bioaccumulation of trace elements in aquatic environments can be influenced by local environmental conditions such as temperature fluctuations, pH levels, sediment composition, dissolved organic matter content, and the presence of other chemical substances. We analyzed the differences in trace elements accumulation (S, Cl, K, Ca, Ti, Cr, Mn, Fe, Cu, Zn, Rb, Sr, Mo, Ba, and Pb) between two trophic guilds-scrapers (Ephemeroptera) and predators (Plecoptera)-of freshwater benthic macroinvertebrates collected from mountain streams in Kazakhstan and Slovakia. Trace elements in dried insect bodies were analyzed using an X-ray spectrometer, and physicochemical parameters of stream water were investigated at each sampling site. Our results showed significant differences in Fe, Ti, and Sr levels in predators from Kazakhstan and Cu levels in predators from Slovakia. Despite some trace elements showing higher concentrations in one group over another, the overall differences between regions were more pronounced. Principal component analysis (PCA) revealed that the primary factors influencing trace elements variability were associated with environmental conditions such as temperature, oxygen levels, and total dissolved solids (TDS). PCA components indicated a higher load of trace elements in the warmer, less oxygenated streams, particularly in Kazakhstan. These findings suggest that both biotic (feeding strategies) and abiotic (geographical and environmental conditions) factors significantly influence trace elements dynamics in freshwater ecosystems.

High-resolution cyclic framework for the Songliao Basin in northeastern China, and its implications for sedimentation and organic matter enrichment

The study of fine-grained sedimentation has consistently concentrated on investigating the mechanisms and principles governing the enrichment of organic matter. However, the lack of unified stratigraphic framework has always existed as fine-grained sedimentation covers two distinct grain-size grades, namely, mud and silt, which has impeded the progress of subsequent production research. This study exemplified this issue by analyzing the first member of the Qingshankou Formation in the southern Songliao Basin. We established reconstructed gamma and density curves that mitigated filter noise interference, integrated high-resolution sequence results with astronomical cycle divisions, and created a high-frequency isochronous stratigraphic framework for clastic fine-grained sedimentation by leveraging the weak sensitivity of sandstone density curves and the robust stability in eccentricity cycle extraction. This approach addresses the inconsistencies in stratigraphic division methodologies and mismatched outcomes stemming from the use varying techniques to delineate mud and silt components within clastic fine-grained sedimentary sequences. Furthermore, it elucidates how tectonic-scale variations in sediment supply coupled with potential accommodation changes dictate macroscopic stacking patterns within strata, whereas climate fluctuations on orbital time scales govern sand-mud progradation degrees within these layers, culminating in periodic rhythmic characteristics characterized by vertical sand-mud interbedding. A model for stratigraphic development pertaining to lake delta systems constrained by a “synchronous heterotopy” paradigm is proposed for the southern Songliao Basin. The organic matter enrichment pattern aligns with its filling dynamics, indicating an “overfilling” type developmental pattern at lower strata levels where organic material predominantly originates from terrestrial plant debris external to the basin; this material accumulates primarily within silty zones along layers—with areas exhibiting heightened enrichment values slightly lagging behind short-eccentric maxima positions. In contrast, under an upper “balanced filling” type developmental framework, sources of organic matter are derived both internally and externally relative to the basin—exhibiting substantial heterogeneity—and regions marked by elevated organic matter concentrations are directly associated with locations identified as short-eccentric maxima.

Organic matter processing by heterotrophic bacterioplankton in a large tropical river: Relating elemental composition and potential carbon mineralization.

River hydrology shapes the sources, concentration, and stoichiometry of organic matter within drainage basins. However, our understanding of how the microbes process dissolved organic matter (DOM) and recycle nutrients in tropical rivers needs to be improved. This study explores the relationships between elemental DOM composition (carbon/nitrogen/phosphorus: C/N/P), C and N uptake, and C mineralization by autochthonous bacterioplankton in the Usumacinta River, one of the most important fluvial systems in Mexico. Our study investigated changes in the composition and concentration of DOM and evaluated carbon dioxide (CO2)production rates (C-CO2) through laboratory experiments. We compared three sites representing the middle and lower river basins, including their transitional zones, during the rainy and dry seasons. After incubation (120 h at 25°C), the DOM decreased between 25% and 89% of C content. Notably, the initial high proportion of C in DOM in samples from the middle-forested zone and the transition led to elevated C-CO2 rates (>10 mg l-1 day-1), in contrast to the lower initial C proportion and subsequent C-CO2 rates (<7 mg l-1 day-1) in the lower river basin. We also found that dissolved organic carbon uptake and NO3- and NH4+ production were higher during the dry season than in the rainy season. The low water flow in the river during the dry season accentuated the differences in elemental composition and microbial processing of DOM among the sites, while the high water flow of the rainy season homogenized these factors. Our findings indicate that microbial metabolism operates with reduced efficiency in C-rich environments like forests, particularly when faced with high C/N and C/P ratios in DOM. This study highlights the influence of the tropical hydrological regime (rainy and dry seasons) and the longitudinal changes in the river basin (middle and lower) topography and land cover on microbial metabolism by constraining DOM characteristics, emphasizing the crucial role of elemental ratios in river DOM processing.

RESEARCH OF THE EFFICIENCY OF ORGANIC MATTER REMOVALFROM WATER USING SYNTHETIC ZEOLITE

The paper investigated the effectiveness of using synthetic zeolite as an adsorbent for the removal of organic matter from water. Characterization of zeolite was performed using advanced testing methods: XRD, FTIR, BET and SEM/EDS. Raw water was analyzed for physicochemical characteristics before treatment (turbidity, color, pH,conductivity, content of organic matter, ammonia, nitrate and nitrite nitrogen, iron, manganese and chloride) and after treatment with an adsorbent (content of organic matter). Research on the efficiency of adsorption was carried out under the conditions of water temperature 25°C, individual doses of zeolite of 1, 2 and 4 g/L, mixing 200 rpm and adsorption time 60 minutes. The obtained results showed that by applying synthetic zeolite in a dose of 1 g/L, it is possible to achieve the removal of organic matter of 71.2%, while increasement of that dose up to four times has an insignificant effect on the adsorption efficiency. KEYWORDS:synthetic zeolite; organic matter removal

Valuable Ca/P Sources Obtained from Tuna Species’ By-Products Derived from Industrial Processing: Physicochemical and Features of Skeleton Fractions

The global tuna canning industry generates substantial volumes of by-products, comprising 50% to 70% of the total processed material. Traditionally, these by-products have been utilized in low-value products such as fish oils and fishmeal. However, there is significant potential to extract high-value compounds from these by-products, such as calcium phosphates (CaP), which can have pharmaceutical, agricultural and biotechnological applications. This work explores the potential of tuna canning by-products, particularly mineral-rich fractions (central skeleton, head and fish bones) as sources of calcium phosphates (CaP), offering a sustainable alternative to conventional synthetic derivatives within a circular bioeconomy framework. By-products from two of the most exploited species (yellowfin and skipjack) were subjected to enzymatic hydrolysis and chemical extraction, followed by controlled calcination to obtain CaP. The content of organic matter, nitrogen, total proteins, lipids and amino acids in the cleaned bones, as well as the main chemical bonds, structure and elemental composition (FT-Raman, XRD, XRF) were evaluated. Results indicated that the highest recovery yield of wet bones was achieved using the chemical method, particularly from the dorsal and caudal fins of yellowfin tuna. The proximal composition, with ash content ranging from 52% to 66% and protein content varying between 30% and 53%, highlights the potential of tuna skeleton substrates for plant growth formulations. Furthermore, variations in crystalline structures of the substrates revealed significant differences depending on the by-product source and species. XRD and Raman results confirmed a monophase calcium phosphate composition in most samples from both species, primarily based on hydroxyapatite (central skeleton, caudal and dorsal fin) or whitlockite/β-tricalcium phosphate (viscera), whereas the heads exhibited a biphasic composition. Comparing the species, yellowfin tuna (YF) exhibited a hydroxyapatite structure in the branchial arch and scales, while skipjack (SKJ) had a biphasic composition in these same regions.

Physical Properties of Soils in Selected Subdivisions in Tacloban City and Palo, Leyte

The study was conducted to analyzed and to determine the physical properties of soil such as texture, bulk density, water holding capacity, soil moisture content, pH, and organic matter content in selected subdivisions in Tacloban City and Palo, Leyte. Analysis of pH, texture, water holding capacity, and organic matter was at the Soil Research Testing and Plant Analysis Laboratory (SRTPAL) Department of Agronomy and Soil Science (DASS) VSU Baybay, Leyte. While the bulk density, soil moisture content was computed using the standard formula. To analyzed the result Analysis of Variance (ANOVA) using the SPSS Program to determine whether soils from subdivisions categorized as waterlogged and mountainous, developed and developing subdivisions derived from their filling and parent materials were significant different. The results showed that soils from various categories from subdivisions had no significant effect on bulk density, water holding capacity, &amp; soil moisture content. However, some properties such as soil pH were significant in the waterlogged and mountainous area. It is recommended that a further study be conducted to include all appropriate soil parameters and procedures such as liming for acid soils, cause of erosion, flooding, water drainage capacity, depth to water table and other significant soil quality parameters. Also recommend for in-depth study by the developers and engineers to ensure that the soil quality be suitable for housing and for the safety of the homeowners.

Treatment of sugarcane vinasse in AnMBR and UASB: process performance and microbial community comparison

Vinasse is a by-product of sugarcane processing which is often used in fertigation; however, the direct use of vinasse harms the environment and reduces soil productivity due to its physicochemical properties. Anaerobic digestion (AD) offers an alternative to mitigate part of the negative effects. Anaerobic high-rate reactors, which mainly rely on sludge granulation, are mostly used in AD of vinasse wastewater. However, the composition of vinasse such as high concentration of solids and organic matter, high salinity, low pH, and high concentrations of sulfate, affect granule formation, leading to sludge washout. Anaerobic membrane bioreactors (AnMBR) present an alternative for vinasse treatment, eliminating the need for sludge granulation and producing a nutrient-rich effluent with minimal residual organics and no suspended solids. Research on sugarcane vinasse treatment using AnMBRs is limited. Most studies have employed submerged internal membrane modules, highlighting the need for further research with different reactor configurations to enhance process performance. In this study, an AnMBR equipped with an external inside-out crossflow ultrafiltration membrane was compared to an upflow anaerobic sludge blanket (UASB) reactor for the treatment of sugarcane vinasse. At a volumetric organic loading rate of up to 6 g COD. L-1.d-1, the UASB reactor reached 75% ± 7% of COD removal efficiency whereas the AnMBR generated a solids-free effluent and reached 88% ± 2% of COD removal efficiency. Microorganisms such as Clostridia, Bacteroidia, Mesotaga, Syner-01, Dehalococcoidia, Bacteroidia-DMER64, and Methanolinea were found as the most abundant. The results highlight the AnMBR potential as an effective alternative for treating sugarcane vinasse while overcoming the challenges posed by unsatisfactory sludge granulation.