Decomposition Of Organic Matter Research Articles

Soil net carbon balance depends on soil C: N: P stoichiometry

Exogenous carbon (C) input may induce priming effects, leading to the loss of soil organic C (SOC) by accelerating the decomposition of native soil organic matter (SOM), while also replenishing SOC through various mechanisms. However, the net C balance resulting from priming and replenishment of SOC under long-term nitrogen (N) fertilization and its stoichiometric regulation mechanisms remain largely undetermined. Soils subjected to 11 years of different N applications were used to investigate the net C balance following the addition of exogenous 13C-labeled glucose. The retention of glucose-derived C exceeded the loss of C caused by the priming effect, resulting in a positive net C balance, albeit attenuated by historical N application (ranging from 25.9 to 36.9 μg C mg−1 SOC). The application of increasing historical N levels resulted in a decrease in soil C:N imbalance and an increase in soil N:phosphorus (P) imbalance, as well as an increase in TERC:N and TERC:P. This suggested that the C and/or P limitations of soil microbial communities were intensified with increased N availability. Soil nutrient stoichiometric imbalance and available resource stoichiometry directly influenced the threshold element ratio, which in turn impacted glucose mineralization, subsequently affecting the net C balance. Collectively, our results provided solid evidence that labile C input could lead to a positive net C balance, which diminished with increased historical N application and was primarily regulated by soil C:N:P stoichiometry. This study highlights the significant implications for the soil C turnover and sequestration under long-term N application management in agroecosystems.

Interaction between POM and pore structure during straw decomposition in two soils with contrasting texture

Particulate organic matter (POM) decomposition is influenced by soil pore structure, and the volume loss associated with POM decomposition might also promote the generation of new pores. However, the interaction between POM decomposition and soil pore structure remains unclear. Therefore, the objective of this study was to explore this interaction during straw decomposition. A 57-day soil incubation experiment was conducted using 13C-labelled maize straw in both Shajiang black soil and Fluvo-aquic soil, with two bulk densities (1.2 g/cm3, T1.2 and 1.5 g/cm3, T1.5). The loss of POM volume and the changes in soil pore structure, both before and after the incubation experiment, were quantified using X-ray micro-computed tomography (μCT). The results showed that there was a significantly greater volume loss of POM in Shajiang black soil (POM volume loss: 58.2–75.0 %) compared to Fluvo-aquic soil (34.0 %). Within the Shajiang black soil, decomposition of POM and the release of respired 13CO2 were notably higher in the soil from the T1.2 treatment compared to the T1.5 treatment (P<0.05), while no significant difference was observed in Fluvo-aquic soil. Image-based porosity and mean pore distance emerged as primary determinants of POM variations in Shajiang black soil. Furthermore, our results underscore the positive role of pores ranging from 50 to 300 μm in diameter (Ø) in facilitating rapid POM decomposition, as evidenced by a higher 13CO2 release. In Shajiang black soil, POM decomposition increased the porosity of 100–200 μm, 200–300 μm, and >300 μm Ø pores by 26.2 %, 51.8 % and 82.9 %, respectively, in the T1.2 treatment (P<0.05), and 50–100 μm Ø pores by 24.7 % in the T1.5 treatment (P<0.05). Our findings emphasize the significance of 100–300 μm Ø pores in gas transport and fresh POM decomposition, highlighting the pivotal role of POM decomposition in shaping soil pore structure.

Additives Improving the Efficiency of Biogas Production as an Alternative Energy Source—A Review

Additives for anaerobic digestion (AD) can play a significant role in optimizing the process by increasing biogas production, stabilizing the system, and improving digestate quality. The role of additives largely boils down to, among others, enhancing direct interspecies electron transfer (DIET) between microbial communities, resulting in improved syntrophic interactions, adsorption of toxic substances that may inhibit microbial activity, improving microbial activity, and increasing process stability and accelerating the decomposition of complex organic materials, thereby increasing the rate of hydrolysis. Through the aforementioned action, additives can significantly affect AD performance. The function of these materials varies, from enhancing microbial activity to maintaining optimal conditions and protecting the system from inhibitors. The choice of additives should be carefully tailored to the specific needs and conditions of the digester to maximize benefits and ensure sustainability. In light of these considerations, this paper characterizes the most commonly used additives and their combinations based on a comprehensive review of recent scientific publications, including a report on the results of conducted studies. The publication features chapters that describe carbon-based conductive materials, metal oxide nanomaterials, trace metal, and biological additives, including enzymes and microorganisms. It concludes with the chapters summarising reports on various additives and discussing their functional properties, as well as advantages and disadvantages. The presented review is a substantive and concise analysis of the latest knowledge on additives for the AD process. The application of additives in AD is characterized by great potential; hence, the subject matter is very current and future-oriented.

Characteristics of Dissolved Organic Matter as Affected by Decomposition of Different Organic Materials in Alpine Wetland

Dissolved organic matter (DOM) plays a significant role in the nutrient supply, energy flow, and pollutant transportation in the wetland ecosystem. However, little is known about the effect of the decomposition of different organic materials in alpine wetland water on the DOM characteristics. By conducting a 90-day decomposition experiment with the addition of different organic materials (peat soil, yak manure, and plant litter) alone or their combinations into alpine wetland water, we characterized the water DOM using three-dimension excitation-emission matrix spectroscopy. The results showed that the decomposition of organic materials significantly affected the chemical properties, sources, humification degree, and composition of the water DOM. The decomposition increased dissolved organic carbon and dissolved total nitrogen in the water. For most of the water samples, a fluorescence index ranging from 1.4 to 1.7 and a biological index of less than 0.8 may indicate that both autochthonous and allochthonous sources contributed to the water DOM, which may primarily rely on allochthonous sources. UVA (37.55–46.81% of total fluorescent components) and UVC fulvic-like substances (29.91–35.53% of total fluorescent components) dominated the water DOM compositions. Among the treatments, additions of peat soil and yak manure led to the highest and the lowest humification degree of the water DOM, respectively. For the treatment of the combination decomposition of all three organic materials, the yak manure may stimulate microbial activity and facilitate the decomposition of plant litter and peat soil and, therefore, boost the humic-like substances in the water DOM. These findings may help the development of wetland biomass management with the objective of maintaining alpine wetland ecosystem services.

Temperature and water content estimation in soils of the semi‐arid region of Brazil using finite difference and CFD

AbstractDetermining the temperature and water content of soil, at a given instant or along time, is fundamental to understand several soil‐related phenomena and processes. Evaporation, aeration, chemical‐reaction rates and types, biological processes such as germination and growth of seeds, root development, nutrient and water uptake by roots, and decomposition of organic matter by microbes, are all strongly influenced by soil temperature. On the other hand, infiltration of water through the soil surface allows soil to temporarily store water, making it available for uptake by plants and organisms living in soil. Furthermore, soil water content is closely related to physical and chemical properties of soil, such as oxygen content and demand, which impacts root breathing, microbial activity and soil chemical balance. The accurate evaluation of these two parameters and their interconnection is even relevant in semi‐arid regions, where climate conditions are particularly difficult, such as the north‐eastern zone of Brazil. Thus, the use of computational models and coupled approaches are imperative for rigorous descriptions. This work presents a contribution to estimate soil temperature and water content, by solving the heat transfer equation and the Richards equation, respectively, through finite differences. As input, the model uses the experimental material composition of the soil, the time‐dependent temperature profile at the surface and information about the regional rain regime. Three different numerical approaches were implemented: explicit, simple implicit and the Crank–Nicolson method. The calculations for temperature and water content of the soil obtained with these computational models were compared with the results from Computational Fluid Dynamics (CFD). The relative differences between the numerical methods were less than 0.006% by solving the heat transfer equation and less than 2.75% using the Richards equation. The maximum relative differences within the model, including both a constant and a variable water‐content profile, were 3.28%. The results from the computational model using the CFX tool have maximum relative differences of 0.6%, which contributes to verifying the accuracy of the implemented methods.

Phosphorus limitation promotes soil carbon storage in a boreal forest exposed to long‐term nitrogen fertilization

AbstractForests play a crucial role in global carbon cycling by absorbing and storing significant amounts of atmospheric carbon dioxide. Although boreal forests contribute to approximately 45% of the total forest carbon sink, tree growth and soil carbon sequestration are constrained by nutrient availability. Here, we examine if long‐term nutrient input enhances tree productivity and whether this leads to carbon storage or whether stimulated microbial decomposition of organic matter limits soil carbon accumulation. Over six decades, nitrogen, phosphorus, and calcium were supplied to a Pinus sylvestris‐dominated boreal forest. We found that nitrogen fertilization alone or together with calcium and/or phosphorus increased tree biomass production by 50% and soil carbon sequestration by 65% compared to unfertilized plots. However, the nonlinear relationship observed between tree productivity and soil carbon stock across treatments suggests microbial regulation. When phosphorus was co‐applied with nitrogen, it acidified the soil, increased fungal biomass, altered microbial community composition, and enhanced biopolymer degradation capabilities. While no evidence of competition between ectomycorrhizal and saprotrophic fungi has been observed, key functional groups with the potential to reduce carbon stocks were identified. In contrast, when nitrogen was added without phosphorus, it increased soil carbon sequestration because microbial activity was likely limited by phosphorus availability. In conclusion, the addition of nitrogen to boreal forests may contribute to global warming mitigation, but this effect is context dependent.

PLTBg investment analysis from agricultural organic waste to produce electrical energy: preliminary potential analysis study and investment in the Caringin Main Market, Bandung

Abstract Biogas is a product of the decomposition of organic matter by microbial decomposers under anaerobic conditions. Biogas consists of various gases, especially methane, carbon dioxide, hydrogen, H2S and other gases as impurities. Biogas can be converted into fuel or electrical energy. One of the potential biogas raw materials is agricultural organic waste. This article and study are based on a survey of the potential for agricultural organic waste produced by the Caringin Main Market. Bandung and the amount of organic waste production reached 84 tons/day, resulting from the trading process in the market. The waste produced by the market is suitable to be used as biogas with an organic content of more than 97.7%; the remaining 2.3% is inorganic waste. Based on the economic and financial analysis, the NPV value was 356,487,559,415.34 and the IRR was 23%, which means it was higher than the interest rate set by the bank, while the PBP value was 5.8 years, much lower set by investors for 10 years and Profitable Index of 4,2 so that this project is declared economically and financially feasible.

Lignite reduces odour from broiler farms without reducing production performance

An unavoidable consequence of chicken meat production is the generation of substantial quantities of spent litter. This poses several environmental and social challenges, as broiler farms become hotspots for odour emissions. The main source of odour from broiler litter is the microbial decomposition of organic material. Thus, lignite's previously shown capacity to reduce microbial activity in broiler litter was expected to reduce odour emissions from broiler housing. The effect of lignite on odour emission rate (OER) (ou/s) was investigated using dynamic olfactometry over two consecutive summer broiler grow-out cycles in Victoria, Australia, with lignite applied at 3.5 kg/m2. The air quality dispersion model, AERMOD, was used to investigate how lignite's effect on OER influenced the predicted odour dispersion distances and concentrations in the context of various Australian regulatory requirements. Additionally, the effect of lignite on bird production performance was also determined. This study showed that lignite reduced the OER from commercial broiler housing by an average of 56% over both grow-outs. This effect was observed for the duration of the trial. The observed reduction in OER reduced the required separation distances by 44–53% according to the state odour criteria for Victoria, New South Wales, Queensland and South Australia. There were no observed differences in feed conversion ratio, bird live weight or mortality throughout either grow-out. This study demonstrated the capacity of lignite to reduce odour emissions from commercial broiler housing without reducing bird production performance.

Positive soil priming effects are the rule at a global scale.

Priming effects of soil organic matter decomposition are critical to determine carbon budget and turnover in soil. Yet, the overall direction and intensity of soil priming remains under debate. A second-order meta-analysis was performed with 9296-paired observations from 363 primary studies to determine the intensity and general direction of priming effects depending on the compound type, nutrient availability, and ecosystem type. We found that fresh carbon inputs induced positive priming effects (+37%) in 97% of paired observations. Labile compounds induced larger priming effects (+73%) than complex organic compounds (+33%). Nutrients (e.g., N, P) added with organic compounds reduced the intensity of priming effects compared to compounds without N and P, reflecting "nutrient mining from soil organic matter" as one of the main mechanisms of priming effects. Notably, tundra, lakebeds, wetlands, and volcanic soils showed much larger priming effects (+125%) compared to soils under forests, croplands, and grasslands (+24…+32%). Our findings highlight that positive priming effects are predominant in most soils at a global scale. Optimizing strategies to incorporate fresh organic matter and nutrients is urgently needed to offset the priming-induced accelerated organic carbon turnover and possible losses.

MEDICAL POTENTIAL OF ARBOREAL FUNGI

Fungi are an extremely important element of ecosystems, playing a key role in the decomposition of organic matter and forming symbioses with plants and animals. The diversity of fungi is enormous, with an estimated 2.2 to 3.8 million species on Earth. Some of these, known as medicinal mushrooms, have been used in medicine for centuries for their therapeutic properties, as described by Hippocrates in ancient times. Modern science is increasingly recognizing the potential of mushrooms not only in medicine but also in the food and biopharmaceutical industries. Current research focuses on the use of mushrooms as a source of valuable bioactive compounds with potential anticancer, immunomodulatory, and antibiotic properties.

Evaluation of the quality of products from multiple industrial-scale composting treatment facilities for kitchen waste and exploration of influencing factors

The aerobic composting process is extensively utilized to manage kitchen waste. Nonetheless, the variability in the quality of compost derived from engineering practices which significantly hinders its broader industrial application. This work investigated the final products of kitchen waste compost at multiple industrial-scale treatment facilities utilizing three distinct aerobic composting processes in a bid to explore key factors affecting compost quality. The quality evaluation was based on technical parameters like seed germination index (GI), and limiting factors such as heavy metal content. The results showed that most of the compost products failed to meet the established standards, with GI being the primary limiting indicator. Furthermore, maturity assessments suggested that compost with low GI exhibited reduced humification could not be recommended for agricultural use. The investigation delved into the primary determinants of GI, focusing on risk factors such as the oil and salt of kitchen waste, and the microbial community of the humification driving forces. The results indicated that products with low GI had higher oil and salt content and a relatively simple microbial community. A thorough analysis suggested that excessive levels oil and salt were potential influencing factors on GI, as they stimulated the activity of acid-producing bacteria like Lactobacillus, suppressed the activity of humification-promoting bacteria such as Actinomarinales, and influenced the decomposition and humification processes of organic matter and total nitrogen, thereby affecting product quality. The findings provide valuable insights for improving kitchen waste compost products for agricultural applications.

Study on the relationship between shale organic matter development and paleowater depth—A new understanding of the condensed section

Recent studies dispute the long-standing belief that highly organic-rich shales are predominantly linked to condensed section (CS) at the maximum flooding surface (MFS), proposing instead that they more commonly develop in shallow waters along basin margins. This hypothesis, however, has not been thoroughly investigated. Our study, focusing on the pivotal regions of the Longmaxi Formation and the Chang 7 Member for marine and continental shale exploration in China, integrates sequence stratigraphy with analyses of total organic carbon (TOC) and elemental geochemistry to pinpoint the environments conducive to the formation of organic-rich shales. The most organic-rich intervals, specifically the bottom of the Longmaxi Formation and the mid-to-lower Chang 73 sub-member, are located within the transgressive systems tract (TST), showing higher TOC levels in the middle to lower TST, compared to the CS of the MFS. The formation of high organic matter shale is related to warm, humid, and dysoxic shallow waters with minimal terrigenous influx and high primary productivity. We found a pronounced inverse relationship between organic matter concentration and water depth, with deeper waters promoting the decomposition and recycling of organic matter during sedimentation, thereby diminishing the TOC content. Moreover, volcanic activity also affected the organic enrichment in the Chang 7 Member. With high primary productivity, organic matter tends to accumulate in dysoxic slope zones. Consequently, high-organic content shale intervals are generally situated in shallow, dysoxic water environments, suggesting that the CS of the MFS may actually represent organic-poor intervals with limited source rock potential. The results of this study are of great significance for shale oil and gas exploration in China, and provide a new direction for the discovery of shale oil and gas sweet spots.

Control of landscape position on organic matter decomposition via soil moisture during a wet summer

Sustainable cropland management requires preservation of soil organic matter (SOM). In spite of in depth understanding gained from ample field and laboratory studies, we have a poor understanding of landscape scale spatial variation of fresh organic matter (OM) decomposition and its conversion into soil organic carbon (SOC). Particularly, local topographic position may be expected to co-control these processes via soil hydrology. In this study, we sought to identify if such control is significant by setting up a field experiment with two contrasting positions across 10 gently sloping cropland fields covering three different soil texture groups, i.e. loamy sand, (sandy) loam and silt loam. We wanted to link OM decomposition to within-field differences in soil moisture, whilst keeping variation in other soil and management factors minimal. Specifically, mesocosms with 13C enriched ryegrass (the OM source) were incorporated in the fields for ten weeks and afterwards, soil was separated into > 500 µm, 53 – 500 µm and < 53 µm sized fractions. Overall, we found that lower located positions were wetter than higher positions with average differences of 11 %, 20 % and 16 % in water-filled pore space for the loamy sand, (sandy) loam and silt loam soil, respectively. Mineralization of added OM was surprisingly independent of landscape position, even though moisture conditions appeared wetter than optimal at the low but not at the high landscape positions. Remaining ryegrass residues > 500 µm did follow local topography-driven gradients in soil moisture with higher amounts in low landscape positions. In other words, drier conditions at high landscape positions improved coarse OM decomposition, with consequently more ryegrass-carbon (C) ending up in finer soil fractions (< 500 µm). Additionally, soil texture affected decomposition of the smallest fraction (< 53 µm) with a stabilizing effect for finer-textured (silt loam) soils. We conclude that, despite significant contrasts in moisture conditions between landscape positions, within-field spatial variability of OM mineralization was overall limited during the observed wet summer period. Nevertheless, landscape position affected the quality of remnant unmineralized C, with relatively more conversion of freshly added OM into OM associated with silt and clay at the drier higher positions, potentially improving the long-term stability of SOM. Likewise observations under different weather conditions are needed to evaluate the necessity of precise modelling of local soil hydrology for predicting SOC stock evolution on the landscape scale.

Metagenomic Analysis of Bottom Sediments of the Karst Meromictic Lake Black Kichier Revealed Abundant Unculturable Thermoplasmatota

Investigations into the microbial community of bottom sediments in the karst lake Black Kichier were conducted. These sediments exhibited elevated levels of sulfide, dissolved methane, and organic matter. Direct radiotracer experiments revealed substantial rates of microbial processes involved in the decomposition of organic matter. Uncultivated archaea belonging to the phylum Thermoplasmatota were identified within the microbial community. Metagenomic analysis unveiled representatives from five orders: Methanomassiliicoccales, Thermoprofundales (formerly known as Marine Benthic Group D and DHVEG-1), DTX01, SG8-5, and Candidatus Gimiplasmatales (formerly UBA10834). These archaea were previously believed to occur exclusively in deep marine sediments characterized by extreme organic matter scarcity. This discovery reshapes our understanding of the role played by Thermoplasmatota archaea, spanning five orders, in the degradation segment of the carbon cycle.

Understanding the differential impact of PFOS and F-53B pollution on reed-mediated soil organic matter decomposition: Insights from rhizosphere priming effect

Plants affect soil microorganisms through the release of root exudates under pollution stress. This process may affect rhizosphere priming effect (RPE) and alter the rate of soil organic matter decomposition. However, the influence of plants on the decomposition of organic matter in soil subjected to pollution stress remains unclear. We studied the effects of exposure to perfluorooctanesulfonic (PFOS) and its alternative, chlorinated polyfluoroalkyl ether sulfonic (F-53B), at concentrations of 0.1 mg/kg and 50 mg/kg on the RPE of reed. We conducted our experiments in an artificial climate chamber and used the natural 13C tracer method to determine RPE. In the PFOS-exposed groups, the RPE was negative, with values of −11.45 mg C kg−1 soil d−1 in the low PFOS group and −8.04 mg C kg−1 soil d−1 in the high PFOS group. In contrast, in the F-53B-exposed groups, the RPE was positive, with values of 8.26 mg C kg−1 soil d−1 in the low F-53B group and 12.18 mg C kg−1 soil d−1 in the high F-53B group. Exposure of reeds to PFOS/F-53B stress resulted in differential effects on extracellular enzyme activities. The observed positive and negative RPE phenomena could be attributed to variations in extracellular enzyme activities. In conclusion, RPE responded differently under PFOS/F-53B exposure.

Design and development of a new stand-alone profiler for marine monitoring purposes

Marine pollution is a complex issue that has prompted extensive research. The Mar Menor lagoon, a singular Mediterranean ecological feature, is under pressure from various economic activities, leading to episodes of hypoxia and fish mass mortality. The lagoon is covered by an extensive meadow of submerged vegetation that release oxygen during daylight hours but consumes it during the night. Under exceptional conditions, the water column becomes stratified, with higher oxygen consumption in the deeper layers due to organic matter decomposition. Therefore, continuous high-frequency monitoring of critical parameters affecting the metabolic behaviour of the lagoon is essential. This marine environment has traditionally been monitored with traditional techniques from vessels on a weekly basis, incurring in high costs and yielding limited results. This article introduces the s-Nautilus, a submersible profiler that enables near real-time data transmission in shallow marine environments. It showcases an operational autonomy of two months and significantly reduces installation costs by eliminating the need for on-site infrastructure and personnel. Weighing 21 kg, makes it easy to transport, and it can be equipped with different commercial sensors to monitor various parameters as required. Currently, several s-Nautilus profilers are deployed in the Mar Menor lagoon, collecting data during critical hours, and providing valuable information to the managers of this emblematic environment.

PERTUMBUHAN DAN HASIL TANAMAN PADI GOGO (Oryza sativa L.) PADA TANAH PODSOLIK (ULTISOL) YANG DIAPLIKASIKAN ZEOLIT FLY ASH

The low productivity of upland rice on Podzolic (Ultisol) soil is caused by various constraints including low pH, the content of macronutrient N, P, K, Ca and Mg, BS and CEC were low, solubility and high Al saturation, high P fixation, delicate to erosion and water availability were low. Applied of zeolite synthesized from coal fly ash with high CEC is expected to overcome these constraints. The high negative charge on zeolite contributes to increasing soil absorption of nutrients provided or dissolved from soil minerals and decomposition of organic matter. The study was conducted experimentally using a completely randomized design, zeolite fly ash as the treatment consisting of 6 levels (0, 100, 150, 200, 250 and 300 kg ha-1) each repeated 3 times. The results showed that the application of zeolite fly ash dose 100-300 kg.ha-1 tends increased the plant height, filled grain number per panicle, the percentage of filled grain and 1000 grain weight compared without zeolite application and the highest increased showed in the number of maximum tillers and productive tillers and weight of milled dry grain per clump was obtained at a dose of 200 kg.ha-1 compared without zeolite is 45, 107 and 106% respectively.

Characterization of carbon dioxide emissions from late stage windrow composting

As organic waste is converted to usable amendments via composting, there are large CO2 emissions associated with the decomposition of organic matter via microorganisms. While the active composting phase produces the largest emissions over a short duration, compost can often be stored during and after the maturation phase for much longer periods of time, increasing cumulative emissions. As such, the objectives of this study were to examine the spatial and temporal variability associated with in situ emissions sampling while identifying the environmental and chemical controls on emissions in windrow composting facilities during and after the maturation phase. A total of 665 flux measurements were taken from four windrows representing different ages and compositions between June and November 2020. Factorial analysis of covariance (ANOVA) was used to determine the variability between sampling locations, while multiple linear regression was used to identify those parameters which had the most influence on CO2 flux. Emissions showed significant variability over time that were attributed to ambient temperatures. During the summer, each windrow reached peak emissions between 5.0 and 32.3 g CO2 m-2 hr-1. As temperatures cooled, the windrows saw a 62%–86% decline in emissions, generally falling below 2 g CO2 m-2 hr-1. Significant differences occurred between the top-most sampling location and all others on the windrow, emitting between 33%–100% more CO2. The environmental controls of surface temperature, moisture content, and internal temperature showed the highest influence on emissions (R2 = 0.62). Chemical properties including organic nitrogen, carbon, pH, magnesium, and nitrate also showed significant influence (R2 = 0.43). This research has shown that environmental factors including temperature and moisture show the strongest influence over emission rates in mature compost. A significant negative effect of organic nitrogen on CO2 flux was found, indicating that increased presence of organic nitrogen would aid in the retention of carbon after the maturation phase, acting to lower total emissions.

Evaluation of the Şerefiye (Zara-Sivas) Dam According to Water Quality Indexes

With the aim of determining the water quality of Şerefiye Dam, Sivas province, the present study was carried out on the samples collected monthly from 3 stations between January 2014 and December 2014. In the analyses, which examined 25 variables, water quality was determined using the World Health Organization drinking water standards, water quality index (WQI), sodium absorption ratio (SAR), sodium percentage, permeability index (PI), magnesium index, irrigation index, and the Surface Water Quality Regulation (SWQR) of the Turkish Ministry of Forestry and Water Affairs. The mean value of water quality index in the dam was found to be 46.82 and the mean value of IWOI irrigation was found to be 3.90. The results obtained here showed that Şerefiye Dam was in the "very good" class in terms of water quality index and irrigation water quality. In addition, there was no oxygen deficiency due to excessive oxygen consumption during organic matter decomposition. The water quality parameters were much lower than the thresholds set in the SWQR, but according to the results of factor analysis (FA), the main variables responsible for the processes in the ecosystem were TSS, COD, SO3, SO4, EC, BOD, NO3, NH4, DO and Fe

Microbiome signature of different stages of hypoxia event in Wonmun Bay

We investigated how microbial communities associated with different hypoxic stages respond to environmental changes across three water depths in Wonmun Bay, South Korea. Analysis of temperature, salinity, dissolved oxygen (DO), and nutrient concentrations revealed prominent seasonal shifts and strong stratification during summer hypoxia. Metabarcoding of prokaryotic 16 S rRNA genes and phototrophic eukaryotic chloroplasts along with quantitative PCR (qPCR) revealed variations in the abundance and composition of these communities. Chloroplast 16 S sequences in May were dominated by land plants (93% of Embryophyta), contrasting with the diverse phytoplankton taxa detected in other months. The water communities in May also had higher total microbial abundance than other months but significantly lower alpha diversity. These results suggest a major influence of freshwater discharge on water communities, pre-conditioning for hypoxia events by promoting organic matter decomposition coupled with DO consumption in bottom water. Subsequently, distinct microbial communities were observed across depths during hypoxia in June and July, while less variability was detected among different depths in September and later months when hypoxia events disappeared. Principal Coordinate analysis (PCoA) demonstrated the distinct patterns of microbial communities in May, June, and July from other months. Both sulfur-oxidizing and sulfate-reducing bacteria (SRB) were prevalent in June while the increase of ammonia-oxidizing archaea (AOA) and ammonia-oxidizing bacteria (AOB) was observed in mid and bottom water in July. This data suggests the intricate interaction between sulfur and nitrogen-cycling microbes during the hypoxia events in Wonmun Bay. In conclusion, this study provides valuable insights into the microbial community responses to the varying environmental conditions at different stages of hypoxia events in eutrophic coastal ecosystems.