High Ammonia Levels Research Articles

High Blood Ammonia Level Is a Predictor of Medium and Large Size Esophageal Varices In Cirrhotic Patients

Background: The development of esophageal varices (EV) and rupture of them are the most serious complications of portal hypertension. Upper gastrointestinal endoscopy is the gold standard for diagnosis of EV but it is a costly and troublesome invasive procedure. To find a non-invasive method for detection of size of EV and to predict the bleeding risk is appealing and would decrease the indications cost and discomfort of upper GI endoscopy. The aim of the study is to evaluate high blood ammonia level is a predictor of medium and large size of esophageal varices in Cirrhotic patients. Methods: This was an observational Cross-sectional study conducted on 40 cirrhotic patients in Department of Gastroenterology, BSMMU using a pre-designed data collection sheet. Information about clinical profile, laboratory parameters- blood ammonia, serum bilirubin, serum albumin, prothrombin time, and ultrasonography of abdomen, endoscopy upper GIT was collected and recorded. The collected data was analyzed by computer with the help of SPSS version 22. Statistical analysis was done by using appropriate statistical tool like Chi-square test, Student’s t- test. P value < 0.05 was considered as significant. Diagnostic efficacy of blood ammonia was calculated by using a value. Results: A total of 40 patients with cirrhosis. Mean age of cirrhotic patients were 47.47±12.98 years. Mean blood ammonia of small size EV of cirrhotic patients was 73.70±32.11 (μmol/L) and medium and large size EV was 118.3±38.37 (μmol/L) (P< .001). At the level of 78.5 (μmol/L), sensitivity and specificity of blood ammonia was 95% and 65% respectively in detection of size of EV. Conclusion: Blood ammonia estimation could be a good tool for identifying individuals with medium and large size esophageal who will need to undergo endoscopy more frequently. Bangladesh J Medicine 2024; 35: 167-172

Larval habitat diversity, physicochemical characterization and their effect on the density of larval malaria vectors in the city of Accra, Ghana.

Malaria is more prevalent in rural areas due to fewer mosquito breeding habitats in urban settings. However, urban factors such as irrigated farming, open sewers, and discarded containers create mosquito breeding sites. This study investigates the diversity and distribution of larval habitats and the impact of physicochemical characteristics on the presence and density of Anopheles gambiae s.l. larvae in Accra, Ghana. Larval surveys and collections were conducted at fifteen locations in Accra, divided into five categories: Irrigated Urban Farming (IUF), Lower Socioeconomic Status (LS), Middle Socioeconomic Status (MS), High Socioeconomic Status (HS), and Peri-urban (PU) areas. Physicochemical parameters were measured, and species identification was performed using morphological and molecular methods. A total of 727 breeding habitats were identified, with 65.34% (475/727) positive for Anopheles larvae. Drainage ditches were the most common habitat type (48.21%, 229/475). The highest abundance of An. gambiae s.l. was found in IUF sites (6,244/22,919), especially during the rainy season (77.01%, 17,650/22,919; R2 = 3.46, P = 0.000). Polluted habitats, including household effluents, had higher ammonium levels (3.4 mg/L NH -N) compared to unpolluted ones (1.3 mg/L NH -N). Other distinguishing parameters included dissolved oxygen (34% vs 52.9%), conductivity (5106 μS/cm vs 2049 μS/cm), and total dissolved solids (3181 mg/L vs 1255 mg/L). The predominant malaria vector was An. coluzzii(54.4%, 368/677). Additionally, the invasive An. stephensi, previously unreported in Ghana, was detected. Malaria vectors breed in diverse and often polluted urban habitats, with high larval densities in urban agricultural areas. The detection of the invasive An. Stephensi highlights the need for continuous monitoring and vector control strategies in urban settings.

A nomogram prediction model for individualized prediction of the risk of covert (minimal) hepatic encephalopathy occurrence in patients with liver cirrhosis

Objective: To construct an individualized nomogram prediction model for predicting the risk of the occurrence of covert hepatic encephalopathy (CHE) in patients with liver cirrhosis. Methods: 325 cases of liver cirrhosis admitted from January 2020 to December 2022 were selected as the study subjects. Patients were divided into training (n=213) and validation (n=112) sets using a cluster randomization method. The risk factors for CHE occurrence in patients with cirrhosis in the training set were analyzed by univariate and multivariate logistic regression. A prediction model related to the nomogram was established. Results: Independent risk factors for the occurrence of CHE in patients with cirrhosis were a history of hepatic encephalopathy, co-infection, gastrointestinal bleeding, severe ascites, prothrombin time ≥16 seconds, high total bilirubin, and high blood ammonia levels (P<0.05). Nomogram model validation results: The model had a net benefit for the training and validation sets, with C-indices of 0.830 (95%CI: 0.802-0.858) and 0.807 (95%CI: 0.877-0.837), respectively, within the range of 0-96%. The calibration curves of both sets were evenly close to the ideal curves. The AUCs for the ROC curves in both sets were 0.827 (95%CI: 0.796-0.858) and 0.811 (95%CI: 0.787-0.836), respectively. Conclusion: Patients with cirrhosis have many risk factors for CHE occurrence. The nomogram model constructed based on these risk factors possesses a good predictive value for assessing CHE occurrence in cirrhotic patients.

The impact of ammonia on particle formation in the Asian Tropopause Aerosol Layer

During summer, ammonia emissions in Southeast Asia influence air pollution and cloud formation. Convective transport by the South Asian monsoon carries these pollutant air masses into the upper troposphere and lower stratosphere (UTLS), where they accumulate under anticyclonic flow conditions. This air mass accumulation is thought to contribute to particle formation and the development of the Asian Tropopause Aerosol Layer (ATAL). Despite the known influence of ammonia and particulate ammonium on air pollution, a comprehensive understanding of the ATAL is lacking. In this modelling study, the influence of ammonia on particle formation is assessed with emphasis on the ATAL. We use the EMAC chemistry-climate model, incorporating new particle formation parameterisations derived from experiments at the CERN CLOUD chamber. Our diurnal cycle analysis confirms that new particle formation mainly occurs during daylight, with a 10-fold enhancement in rate. This increase is prominent in the South Asian monsoon UTLS, where deep convection introduces high ammonia levels from the boundary layer, compared to a baseline scenario without ammonia. Our model simulations reveal that this ammonia-driven particle formation and growth contributes to an increase of up to 80% in cloud condensation nuclei (CCN) concentrations at cloud-forming heights in the South Asian monsoon region. We find that ammonia profoundly influences the aerosol mass and composition in the ATAL through particle growth, as indicated by an order of magnitude increase in nitrate levels linked to ammonia emissions. However, the effect of ammonia-driven new particle formation on aerosol mass in the ATAL is relatively small. Ammonia emissions enhance the regional aerosol optical depth (AOD) for shortwave solar radiation by up to 70%. We conclude that ammonia has a pronounced effect on the ATAL development, composition, the regional AOD, and CCN concentrations.

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.

Pertumbuhan Ikan Komet (Carassius auratus) pada Sistem Vertiqua dengan Menggunakan Biofikal Filter

The growth of comet fish (Carassius auratus) in the vertiqua system using a biofical filter is motivated by limited land and water which can cause low water quality to affect the growth rate of fish. The utilization of technology needs to be done to overcome these problems and the technology used is vertiqua. Previous research showed that comet fish in the vertiqua system produced slow growth rates and had high ammonia levels. Therefore, vertiqua was modified in the filter section to become a biofical filter. The purpose of this research is to test the effectiveness of comet fish growth in the vertiqua system using a biofical filter. The benefits of this research are that the vertiqua system using a biofical filter can be a solution to overcome the problem of limited land and water, become a support for system cultivation innovation, and become a reference for further research. This research method uses descriptive methods, observation and interviews. The comet fish used in the study were 3-4 cm in size. The results of this study indicate that the vertiqua system using a biofical filter is still not effective in supporting fish growth. The growth rate of comet fish in the vertiqua system is significantly different from that in the soil pond and the growth rate of comet fish in the vertiqua system is lower than that of comet fish in the soil pond. Ammonia value is relatively high from the quality standard (&gt;0.05). However, this system is able to maintain good fish survival and good water quality, especially in temperature, pH, and DO.

Various effects of feeding level on ammonia tolerance in Carassius auratus under different ammonia exposure stress and the underlying mechanisms

Elevated ammonia levels in aquaculture systems could reduce fish growth and survival rates and produce a range of physiological problems. Ammonia toxicity in aquatic environments was regulated by various factors. Feeding was usually reported to help in the detoxification of fish, thereby increasing their capacity to tolerate ammonia nitrogen. However, the impact of different feeding amounts on fish in relation to ammonia exposure stress remains to be determined. To determine how feeding levels affected fish's responses to different ammonia nitrogen concentrations, two acute toxicity experiments were conducted with Carassius auratus gibelio, the major strain of gibel carp in aquaculture systems in China. In Test I, fed Carassius auratus gibelio (3 % body weight) showed a higher survival rate under a specific ammonia exposure stress. 96-h LC50 of NH3-N to 3 %F gibel carp was 1.1 times greater than that for NF (no feeding). In Test II, all fed groups (2 %F and 4 %F) under low and high ammonia stress exhibited improved ammonia detoxification, evidenced by higher liver GSase, GDH, and glutamine concentrations compared with the NF treatment. Muscle glycogen levels in feeding treatments were higher than those in NF, indicating that fed fish have more energy for ammonia detoxification. While compared with low ammonia treatment (2.70 mg L−1 TAN; NH3 0.06 mg L−1), fish exposed to high ammonia levels (26.03 mg L−1 TAN; NH3 0.57 mg L−1) demonstrated a decrease in food consumption, severe histopathological alterations in their liver, gill, and kidney, and decreased GSase, GDH, and glutamine production in the liver and brain. The results partly supported our hypothesis and suggested that increasing feeding enhances gibel carp's tolerance to ammonia nitrogen. The highest detoxification metabolism was observed under low ammonia stress. While excessive ammonia exposure could inhibit feeding and damage the detoxification organs of fish, and thus reduce the detoxification metabolism of gibel carp.

Lab-Scale Treatment of Anaerobic Co-Digestion Liquor from Kitchen Waste, Human Feces, and Municipal Sludge Using Partial Nitritation-Anammox Process

Effective nitrogen removal from anaerobic co-digestion is a major challenge to achieving dual-carbon goals. This study explored the acclimatization process of a lab-scale two-stage partial nitritation and anammox process of a stepwise increase in the percentage of raw anaerobic co-digestion liquor from kitchen waste, human feces, and municipal sludge in a venous industrial park in China, which has not been reported yet. Under limited dissolved oxygen (below 0.5 mg/L) and high ammonia levels (200–1500 mg/L), based on adjusting aeration rates, partial nitritation rapidly started up in 50 days. After acclimatization, partial nitritation still performed efficiently and stably, with the final total nitrogen loading rate (TNLR) of 1.24 ± 0.09 gN/L/d, nitrite accumulation rate of 99 ± 4%, and ratio of eff. nitrite/ammonia of 1.32 ± 0.13. In the anammox process, the final total nitrogen removal efficiency, total nitrogen removal rate, and TNLR reached 94 ± 5%, 1.27 ± 0.03 gN/L/d, and 1.36 ± 0.05 gN/L/d, respectively. Chemical oxygen demand (COD) was also reduced in both reactors, with COD removal rates of 0.7 gCOD/L/d in the partial nitritation and 0.4 gCOD/L/d in the anammox process. Overall, the PNA system demonstrated its feasibility in adapting to high ammonia, salinity, and iron levels, when treating anaerobic co-digestion liquor, particularly regarding resource recovery in venous industrial parks.

Mutational analyses of mitochondrial ATP6 gene reveal a possible association with abnormal levels of lactic acid and ammonia in Bangladeshi children with autism spectrum disorder: A case-control study

Autism spectrum disorder (ASD) is a multifactorial and highly heterogeneous neurodevelopmental disorder. Mitochondrial dysfunction, caused by the genetic variations in the electron transport chain (ETC) complexes and marked by higher lactic acid and ammonia levels, can play a crucial role in the development of autism. This study focused on identifying genetic variants in the mitochondrial ATP6 gene of children with ASD and their association with autism disease outcome, disease severity, lactic acid and ammonia levels. Ninety children were recruited of which 53 were with autism and the remaining 37 were healthy controls. The ATP6 gene was amplified by PCR, purified, and sequenced by Sanger sequencing. In total forty-two genetic variants were identified within the gene. Among them 8886G > A and 8911 T > C were found to be associated with higher lactic acid levels and 8748C > T, 8886G > A, and 8964C > T were associated with higher ammonia levels after the adjustment with age, gender, and disease response. Additionally, all the synonymous variants were found to alter the relative synonymous codon usage (RSCU) values, potentially affecting the protein's structure and translation rate. Although there was no significant association between any ATP6 variants and disease outcomes, the variants associated with mitochondrial dysfunction as reflected by abnormal levels of lactic acid and ammonia may provide an improved understanding of the pathophysiology of ASD. Therefore they need to be explored further along with other components of the electron transport complex.

First record of iridovirus (ISKNV) infections in Fourfinger threadfin from Kuwait

Following an initiative by the Govt. of Kuwait and the Kuwait Institute for Scientific Research (KISR), the institute started simultaneous efforts of domestication of locally caught fish and hatchery production of Fourfinger threadfin (FFT, Eleutheronema tetradactylum), locally called Sheem. A private farm and KISR are working together to optimize the conditions for growth and spawning performances under the environmental conditions of Kuwait. During these efforts, infectious spleen and kidney necrosis virus (ISKNV), an important fish pathogen from Iridoviridae, caused mortalities of the FFT sub-adults (150–200 g). We noticed that the mortality was associated with anorexia, haemorrhages of the snout, fin bases, and scale pockets. We also noticed that this was typical to one of the tanks that had consistently high ammonia (0.2–0.25 ppm) levels in the water, and all 35 sub-adults died within 4–5 days. Diagnostics (molecular and electron microscopy examinations) revealed ISKN iridovirus as the causative. We noticed viral particles of 150–200 nm in the tissue sections of the skin, gills, heart, liver, spleen, kidney, and intestine. The major capsid protein (MCP) gene sequence analysis confirmed the results, revealing 98 % similarity with the laminin-type epidermal growth factor-like protein gene of ISKNV. The present report is the first record of ISKNV infections in FFT and from Kuwait. The study aimed to decipher the cause of illness and mortality of cultured FFT.

Revealing degradation pathways of soluble and dissolved organic matter in alluvial-lacustrine aquifer systems impacted by high levels of geogenic ammonium

The excessive presence of geogenic ammonium (NH4+) in groundwater poses a global environmental concern, commonly linked to the degradation of nitrogen-containing dissolved organic matter (DOM). However, there is a gap in systematic studies on the combination of soluble organic matter (SOM) in sediments and DOM in groundwater, with few indoor incubation experiments to validate their degradation pathways. This study utilized ultrahigh-resolution Fourier transform ion cyclotron resonance mass spectrometry to analyze the molecular characteristics of DOM and SOM in aquifer systems affected by geogenic NH4+. Subsequently, indoor incubation experiments spanning up to 140 d were conducted to verify the degradation pathways. The experimental results revealed a two-phase degradation process for both the DOM and SOM. The initial stage was characterized by the degradation of aliphatic compounds (ALC) with the production of polyphenols (PPE) and highly unsaturated compounds (HUC). The second stage was dominated by the degradation of PPE and HUC, accompanied by the re-consumption of some ALC, while more recalcitrant HUC persisted. Notably, the first stage of SOM degradation exceeded that of DOM degradation, indicating that SOM exhibited greater resistance to aging. This phenomenon may be attributed to a wider range of active enzymes in sediments, the rapid replenishment of SOM by organic matter in sediments, or the accelerated degradation of DOM. The experimental results aligned with the molecular characterization of DOM and SOM in actual aquifer systems. It is hypothesized that NH4+ produced through the direct mineralization of SOM may contribute more to the enrichment of NH4+ in groundwater than that produced through the mineralization of DOM. This study is the first to analyze DOM and SOM together in aquifer systems and validate their degradation pathways through incubation experiments, thereby providing novel insights into the enrichment of geogenic NH4+ in groundwater.

Validity of Serum Ammonia Level for Diagnosis of Severity of Hepatic Encephalopathy in Children

Hepatic encephalopathy is a broad spectrum neuropsychiatric abnormalities of liver dysfunction. Ammonia level may correlate with the severity of liver failure. The brain is very sensitive to the toxic effects of ammonia. As a result patient may manifests with irritability, slurring of speech, reversal of sleep-awake cycle, flapping tremor, confusion, stupor or even deep coma. This study was aimed to validate the ammonia level in children with liver failure for the assessment of its severity considering hepatic encephalopathy. This cross-sectional comparative study was conducted among 64 children aged 1-15 years of both sexes (study subjects) diagnosed as acute or acute on chronic liver failure in the Department of Pediatric Gastroenterology and Nutrition, Bangabandhu Sheikh Mujib Medical University (BSMMU), Dhaka, Bangladesh during the period of November 2017 to September 2019. The subject were divided into two groups for the comparison of ammonia level to assess the severity in contrast to hepatic encephalopathy. In the first group 32 were liver failure with encephalopathy and in the second group 32 were liver failure without encephalopathy. Hepatic encephalopathy was diagnosed on the basis of West Haven Criteria. The analysis was done by the Receiver Operating Characteristic Curve with SPSS-20. Among the 64 patients female were 45% whereas male patients were 55%, male female ratio was 1.2: 1. Regarding etiology, Wilson disease was the most common cause and it was nearly two-third (65.6%) of children, cryptogenic cirrhosis was 10%, Hepatitis A was 9.4%, Autoimmune Hepatitis (AIH) was 3.10%, Hepatitis E, Hepatitis B, Hepatitis C, biliary atresia and lipid storage were 1.60% respectively. This study showed that, ammonia of ≥71 µmol/L is an indicator for presence of hepatic encephalopathy in children. The analysis by the Receiver Operating Characteristic Curve showed area under the curve (AUC) is 0.86 with upper bound 0.96 and lower bound is 0.77. It was observed that about half (48.4%) of the children had positive blood ammonia level (≥71.0 umol/L) and among the children of positive blood ammonia level most of them (80.65%) had hepatic encephalopathy and 19.35% had no encephalopathy. More than half (51.6%) children had negative (&lt;71.0 umol/L) blood ammonia level, among them 21.21% children had encephalopathy and 78.79% patients had no encephalopathy. Sensitivity of blood ammonia was found 78.1%, specificity 81.2%, positive predictive value 80.6%, negative predictive value 78.8% and accuracy 79.7%. In conclusion, high level of ammonia is found with higher grade of encephalopathy and hyperammonia is also found in liver failure without encephalopathy. Bangladesh Med J. 2023 May; 52(2): 1-5

Genome-Wide Identification and Characterization of Ammonium Transporter (AMT) Genes in Chlamydomonas reinhardtii.

Ammonium transporters (AMTs) are vital plasma membrane proteins facilitating NH4+ uptake and transport, crucial for plant growth. The identification of favorable AMT genes is the main goal of improving ammonium-tolerant algas. However, there have been no reports on the systematic identification and expression analysis of Chlamydomonas reinhardtii (C. reinhardtii) AMT genes. This study comprehensively identified eight CrAMT genes, distributed across eight chromosomes, all containing more than 10 transmembrane structures. Phylogenetic analysis revealed that all CrAMTs belonged to the AMT1 subfamily. The conserved motifs and domains of CrAMTs were similar to those of the AMT1 members of OsAMTs and AtAMTs. Notably, the gene fragments of CrAMTs are longer and contain more introns compared to those of AtAMTs and OsAMTs. And the promoter regions of CrAMTs are enriched with cis-elements associated with plant hormones and light response. Under NH4+ treatment, CrAMT1;1 and CrAMT1;3 were significantly upregulated, while CrAMT1;2, CrAMT1;4, and CrAMT1;6 saw a notable decrease. CrAMT1;7 and CrAMT1;8 also experienced a decline, albeit less pronounced. Transgenic algas with overexpressed CrAMT1;7 did not show a significant difference in growth compared to CC-125, while transgenic algas with CrAMT1;7 knockdown exhibited growth inhibition. Transgenic algas with overexpressed or knocked-down CrAMT1;8 displayed reduced growth compared to CC-125, which also resulted in the suppression of other CrAMT genes. None of the transgenic algas showed better growth than CC-125 at high ammonium levels. In summary, our study has unveiled the potential role of CrAMT genes in high-ammonium environments and can serve as a foundational research platform for investigating ammonium-tolerant algal species.

Effect of methane addition on supercritical water oxidation of poultry manure in the flow mode

The paper presents the research results of the supercritical water oxidation (SCWO) of poultry manure continuously fed into a tubular reactor both in the absence and presence of methane as an auxiliary fuel. The tests were conducted at a temperature gradient along the vertical axis of the reactor (top to bottom: 390–600 °C), a pressure of 25 MPa, and varying reagent flow rates. It is shown that due to heat generation during methane oxidation the energy consumption from external sources is reduced by 1.3–1.5 times depending on the ratio of reagent flow rates. The gas products contain CO2, N2, and trace amounts of N2O. The ash residues are predominantly composed of calcite and hydroxyapatite. The addition of methane results in a reduction in the content of phenols and polycyclic aromatic hydrocarbons present in the aqueous effluent, while content of N-bearing aromatics increases. The formation of nitrophenols was observed at elevated oxygen concentrations in the reaction mixture. It was revealed that excess oxygen plays a pivotal role in the efficacy of organic nitrogen removal. The formation of mineral acids and a high level of ammonia in the reaction mixture during the SCWO of poultry manure result in corrosion of stainless steel and copper seals, which in turn leads to an increased concentration of chromium and copper in the aqueous effluent. The results obtained indicate the potential for utilizing natural gas in an environmentally friendly and resource-saving manner for poultry manure processing by SCWO in autothermal mode.

Chromophoric dissolved organic matter traces seasonally changing coastal processes in a river-influenced region of the western Bay of Bengal.

The optical characteristics of colored dissolved organic matter (CDOM) serve as a convenient tool for evaluating coastal processes, e.g., river runoff, anthropogenic inputs, primary production, and bacterial/photochemical processes. We conducted a study on the seasonal and spatial variability of absorbance and fluorescence characteristics of CDOM and nutrients in the coastal waters near the Gauthami estuary of River Godavari, the largest peninsular river of India, for a year. The surface aCDOM(350) showed a significant inverse relation with salinity in the coastal region, indicating a conservative mixing of marine and terrestrial end members. The aCDOM(350) was not conservative in the offshore (100m isobath) waters due to enrichment by secondary sources. Seasonal variability in optical properties indicated diverse sources for CDOM, as revealed by principal component analysis. The excitation-emission matrix (EEM) spectra followed by parallel factor analysis (EEM-PARAFAC) revealed four distinct fluorophores. The tyrosine (B) fluorophore showed a predominant increase in the post-monsoon season (October to January), while tryptophan (T) was relatively more enriched, coincident with nutrient enrichment and transparency increase during the early monsoon phase (July). The biological index (BIX), which reflects recent photosynthetic activity, also displayed relatively higher values during the early monsoon. The humic fluorophores A and M, and humification index (HIX) were relatively enriched during the later phase of monsoon (July-October). HIX was > 4 in a few samples of the offshore region (100-m isobath) and indicated a probable contamination from drill-mud (bentonite) used in hydrocarbon exploration. During the monsoon, the relationship between T and B with CDOM was not evident due to the masking of B fluorescence in intact protein. However, during the post-monsoon (POM) and pre-monsoon (PRM) periods, this masking effect was not observed, likely due to protein degradation via bacterial and photochemical processes, respectively. Temporal variability in nutrients indicated that high ammonium levels were produced during POM (OM bacterial degradation), and high nitrite levels were observed during PRM (due to primary production). This study provides foundational insights into the use of CDOM for understanding the impact of diverse environmental, river discharge, and anthropogenic factors on coastal ecosystems.

Evaluating Ammonia Toxicity and Growth Kinetics of Four Different Microalgae Species.

Although wastewater with high ammonia concentration is an ideal alternative environment for microalgae cultivation, high ammonia concentrations are toxic to microalgae and inhibit microalgae growth. In this study, the ammonia responses of four widely used microalgae species were investigated. Chlorella vulgaris, Chlorella minutissima, Chlamydomonas reinhardtii and Arthrospira platensis were grown in batch reactors maintained at seven different NH4Cl concentrations at a constant pH of 8. Growth and nitrogen removal kinetics were monitored. IC50 values for the mentioned species were found as 34.82 mg-FA/L, 30.17 mg-FA/L, 27.2 mg-FA/L and 44.44 mg-FA/L, respectively, while specific growth rates for different ammonia concentrations ranged between 0.148 and 1.271 d-1. C. vulgaris demonstrated the highest biomass growth under an ammonia concentration of 1700.95 mg/L. The highest removal of nitrogen was observed for A. platensis with an efficiency of 99.1%. The results showed that all tested species could grow without inhibition in ammonia levels comparable to those found in municipal wastewater. Furthermore, it has been concluded that species C. vulgaris and A. platensis can tolerate high ammonia levels similar to those found in high strength wastewaters.

High rhizospheric ammonium levels in Sorghum halepense (johnsongrass) suggests nitrification inhibition potential

AbstractPlants, such as sorghum (Sorghum bicolor), have been shown to secrete root exudates involved in biological nitrification inhibition (BNI), an ability to suppress the conversion of ammonium to nitrate and thereby minimize its loss. Johnsongrass (Sorghum halepense), a weedy relative of cultivated sorghum, may also possess BNI potential, but little is known in this regard. Here, we conducted a field survey at seven different sites in Southeast Texas to determine this evolutionary trait of johnsongrass in different soil environments. It was found that johnsongrass rhizosphere retains high levels (&gt;60%) of ammonium within the total available N (ammonium + nitrate). Furthermore, the degree of ammonium retention by johnsongrass rhizosphere was significantly greater (up to 40%) in the roadside habitat compared to cultivated fields. The high ammonium retention potential by johnsongrass may explain, in part, their persistence and dominance, especially in marginal environments.Core Ideas Nitrogen is a limiting nutrient for plant growth, and nitrification causes loss of nitrogen. Ammonium retention was higher in roadside johnsongrass biotypes compared to that of cropland biotypes. The high rhizoshpheric ammonium retention by johnsongrass may explain, at least in part, its invasiveness. This trait could be further investigated and integrated into modern sorghum cultivars.

Feeding rates affect growth, metabolism and oxidative status of Nile tilapia rearing in a biofloc system.

The biofloc system is a biotechnology available for fish farming. Feeding rate is an important factor as it influences production costs and fish performance. The aim og this study was to evaluate the effects of feeding rates (2, 4, 6 and 8%) on growth, body composition, biochemical parameters and thiobarbituric acid-reactive-substances in tilapia. An experiment was conducted for 4 weeks, using 144 tilapias juvenile (initial weight = 12.06 ± 0.16g), in triplicate for feeding rate tested. Fish fed three times a day, with comercial extrude diet (36%CP). After the end of the experiment, measurements were carried out and samples were collected for analysis. The feeding rate of 6% increased fish growth parameters, not differing between 4 and 8%. Since apparent feed conversion increased proportionally to increase in feed supply. Body protein of fish was higher at 8% feeding rate and the dry matter raised according to the rate. The feeding rates affected the body lipids in fish. Fish that fed 6% and 8% showed more lipid in the whole body. The biochemical parameters presented a lower amount of protein, amino acids, and hepatic glucose when employing a feed rate of 6%. Higher levels of ammonia were observed in the muscle of fish reared at 4% of feeding rate. There was no difference in amino acids and ammonia regarding the gills. Fish reared at lower feeding rates (2% and 4%) showed better oxidative parameters, which may be due to the consumption of the biofloc phenolic compounds. We recommend the use of a 4% feeding rate for juvenile tilapia in a Biofloc Technology system.

Cliff nesting birds provide nutrient inputs to cliff ecosystems

Allochthonous inputs often link nutrient cycles between different ecosystems as nitrogen (N) that originates in one ecosystem is transferred to another. Mobile animals such as birds and fish can translocate nutrients between locations. Consequently, animal-mediated nutrient subsidies can shape plant communities, especially in nutrient-poor ecosystems. Terrestrial cliffs are typically nutrient-poor, receiving N from atmospheric deposition and cliff-top runoff. Cliff nesting birds deposit N-rich excrement onto the cliff during nesting, yet this potential nutrient input has rarely been demonstrated. Here we document an allochthonous input of N from cliff-nesting birds to terrestrial cliff vegetation. We sampled mineral N and vegetation on eight cliff systems in western North Carolina (USA) with nests from peregrine falcon (F. peregrinus; two sites) and common raven (Corvus corax; five sites). Two sites had nests but species identity was not confirmed. Cliff faces below bird nests had higher levels of ammonium (NH4+) than did faces without nests. Both ammonium and nitrate (NO3−) explained variability in cliff vegetation community composition, but site-level characteristics explained more of the variation than did N inputs alone. Lichens, the dominant taxonomic group, contributed the most to this variation and had higher species richness and diversity below nests. Indicator species analysis identified two nitrophilic lichen species below nests: Flavoplaca citrina and Physcia caesia. A third nitrophilic lichen, Polycauliona candelaria (syn. Xanthoria candelaria) was also found under nests. Bird excrement is likely a significant subsidy to nutrient-poor terrestrial cliff ecosystems, thus linking cliffs to more productive ecosystems and highlighting the need to include birds in conservation and management of cliffs.

Flexible gas-strain dual sensor based on PU-supported Ti3C2Tx/CeO2/TiO2 yarns

The generation of high levels of ammonia in industries, agricultural sectors, and water treatment plants has triggered the necessity to detect high ammonia concentrations in a flexible way to ensure proactive measures for protecting humans and the environment. Therefore, it is essential to develop highly sensitive multifunctional sensors that have long-term stability, high durability, and a large stretch range. In our work, a novel approach was developed for fabricating flexible sensors consisting of polyurethane (PU) yarn and the loaded Ti3C2Tx/CeO2/TiO2 (abbreviated as MTCe) nanocomposites. The structures and morphology of the yarn-shaped sensors were analysed using X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), and other characterisation methods. In addition, gas and strain responses were recorded and analysed using an AES-4SD flexible electronic device. The response of the yarn-shaped sensors to 100 ppm NH3 was 42.9 % at room temperature (25 °C), indicating its excellent gas sensitivity. In addition, the sensors exhibited some key advantages, such as a large stretch range (60 %), high sensitivity (up to 385.285), and good durability (200 stretches/releases at 20 % stretch), which may be considered a remarkable achievement in the field of flexible sensor manufacturing for multiple applications.