Ammonia Concentration Research Articles

Unraveling Functional Diversity Patterns in Hyporheic Zones: A Trait-Based Approach Applied to Copepods from the Rio Gamberale Creek

Despite the recognized ecological significance of hyporheic zones, biological investigations into their ecology, especially concerning functional diversity, remain limited. This is particularly true for copepod assemblages, abundant in the transitional zone between groundwater and surface waters, requiring more thorough exploration. To bridge this knowledge gap, our study extensively monitored a hyporheic zone within a mountain creek and examined nine functional traits across twelve copepod species found in this environment. Through the application of RLQ and fourth-corner analysis, as well as functional diversity indices including functional richness, evenness, divergence, and dispersion, we aimed to establish links between functional traits and environmental factors. Our findings revealed relationships between environmental features—specifically electrical conductivity, pH, and ammonium concentration—and the trait composition of copepod assemblages, which were influenced by species abundances. Considering the intimate connection between functional traits and ecosystem services, assessing functional diversity within hyporheic zones offers valuable insights into its functionality in terms of services rendered. This study emphasizes the importance of understanding and managing functional diversity in hyporheic zone dynamics to ensure the health and stability of ecotones and, by extension, riverine and groundwater ecosystems.

An attempt to augment performance of machine learning models in a pilot-scale urban wastewater treatment system

The challenge we face is striking a balance between ensuring the standards for wastewater treatment processes and minimizing energy consumption. As such, accurate predictive models become critical. With machine learning algorithms having the ability to discern relationships between inputs and outputs, broad interest has been shown in their applications in wastewater treatment. A key research focus is on effectively adjusting these generic machine learning algorithms to adapt to frequent fluctuations of water quality, inflow volume, and environmental variations. This study developed a Nonlinear Autoregressive neural network (NARX) model having an adaptive real-time updating module to predict the ammonium concentration in the treated effluent. The model has exhibited high predictive accuracy on the testing data, achieving an R2 value of 0.997. By incorporating an adaptive real-time updating module, the model's capability to predict effluent ammonium concentration on novel data sets has been significantly improved, with the R2 value for these predictions increasing from an initial 0.918 to a more refined range of 0.966 to 0.984. Our findings confirm that integrating real-time updating capabilities with machine learning algorithms substantially improves the stability and predictive performance of the models. These outcomes will prompt a broader integration of artificial intelligence in the domain of environmental engineering, which shall foster the implementation of more accurate and eco-friendly wastewater treatment strategies.

Appropriate Application of Organic Fertilizer Can Effectively Improve Soil Environment and Increase Maize Yield in Loess Plateau

Fertilization has a significant impact on soil nutrients and microbiological properties, which, in turn, affect crop yield. However, the specific effects of organic and inorganic fertilizers on soil fertility and microbial characteristics in maize fields, as well as the key soil factors influencing changes in crop yield, remain largely unknown. A study was conducted over two years (2021–2022) to investigate the impact of various nitrogen fertilization rates and types on maize yield and soil properties in the Loess Plateau. Field experiments with five nitrogen levels (60, 90, 120, 150, and 180 kg N ha−1) and two fertilizer types (chemical and organic) were conducted. The optimal yield was achieved with 150 kg N ha−1, significantly surpassing that of other treatments by 4.5−45.7%. Compared with the organic fertilizers, the chemical fertilizers increased soil salt and catalase levels, with soil nitrate and ammonium content being higher at the jointing stage but lower at maturity. Organic fertilization improved soil potassium, organic matter, urease and phosphatase activities, and microbial populations. Yield correlated with several soil indicators, including salt content, nitrate, available potassium, and enzyme activities. Notably, soil nitrate also correlated with actinomyces quantity. A principal component analysis showed that the organic fertilizer was more beneficial to soil health than the chemical fertilizer. Consequently, this study recommends 150 kg N ha−1 of organic fertilizer for sustainable maize farming and soil health in China’s northwest arid region, providing a theoretical framework for agricultural practices.

Synthesis and experimental investigations of a photoactive naphthopyran for sensing nanomolar concentration of ammonia

Selective detection and identification of toxic analytes such as trace gases hold significant relevance in supramolecular host–guest functional systems. Identification becomes easier when the detection tool is prone to fluorescence enhancement instead of quenching. A judiciously designed substituted naphthopyran derivative was synthesized and its interactions with several amine guests have been investigated. The probe displayed enhancement in fluorescence signal on interaction with ammonia. Based on fluorescence spectroscopy a limit of detection value of 56 nM was witnessed for ammonia. Molecular level interaction analysis performed using 1H NMR spectroscopy indicated ring opening of naphthopyran derivative induced by ammonia. The designed naphthopyran probe might be useful as a tool for portable NH3 sensing.

Tracing the contribution and fate of synthetic nitrogen fertilizer in young apple orchard agrosystems

Excessive synthetic nitrogen (N) inputs in intensive orchard agrosystems of developing countries are a growing concern regarding their adverse impacts on fruit production and the environment. Quantifying the distribution and contribution of fertilizer N is essential for increasing N use efficiency and minimizing N loss in orchards. A 15N tracer experiment was performed in a young dwarf apple orchard over two growing seasons to determine the fertilizer N transformation and fate. Fertilizer N primarily contributed to 25 % to 75 % of soil nitrate in the top 60 cm, but the contribution to soil microbial biomass N and fixed ammonium was <8 %, with the contribution to plant N ranging from 9 % to 19 %. In most growth periods, soil nitrate and fixed ammonium contents derived from native soil with N fertilization were higher than those not receiving N fertilizer. The N use efficiency of plants was only 2.6 % and 4.9 % in the first and second seasons, respectively, in contrast to 56.6 % and 54.0 % of N recovered in soil. Meanwhile, N assimilated into microbial biomass accounted for 0.8 %, and the proportion fixed by clay minerals was 3.5 %–5.2 %. One season after N fertilization, the nitrate below the 1 m soil layers accounted for 4.6 % of the applied N fertilizer, and the proportion increased to 22.5 % after two seasons. The N loss rate via N2O emission was 0.4 % over two years. The application of N fertilizer facilitated indigenous soil N mineralization, and abiotic ammonium fixation more efficiently retained synthetic N than microbial immobilization. These findings provide new insight into orchard N cycling, and attention should be given to the improvement of soil N retention and turnover capacity regulated by soil microbial and abiotic processes, as well as the potential environmental impacts of additional soil N mineralization resulting from prolonged chemical N fertilization.

A lysing polysaccharide monooxygenase from Aspergillus niger effectively facilitated rumen microbial fermentation of rice straw.

This study investigated the impact of Aspergillus niger lysing polysaccharide monooxygenase (AnLPMO) on in vitro rumen microbial fermentation of rice straw. AnLPMO was heterologously expressed in Escherichia coli. Fourier transform infrared spectrometry and X-ray photoelectron spectroscopy analyzed the surface structure of rice straw after AnLPMO treatment. Two in vitro experiments, coupled with 16S highthroughput sequencing and quantitative real-time polymerase chain reaction techniques, assessed the influence of AnLPMO on rumen microbial fermentation of rice straw. AnLPMO exhibited peak activity at 40°C and pH 6.5, with a preference for rice straw xylan hydrolysis, followed by Avicel. AnLPMO application led to the fractional removal of cellulose and hemicelluloses and a notable reduction in the levels of carbon elements and C-C groups present on the surface of rice straw. Compared to the control (no AnLPMO), supplementing AnLPMO at 1.1 to 2.0 U significantly enhanced in vitro digestibility of dry matter (IVDMD, p<0.01), total gas production (p<0.01), and concentrations of total volatile fatty acids (VFA, p<0.01), acetate (p<0.01), and ammonia-N (p<0.01). Particularly, the 1.4 U AnLPMO group showed a 14.8% increase in IVDMD. In the second experiment, compared to deactivated AnLPMO (1.4 U), supplementing bioactive AnLPMO at 1.4 U increased IVDMD (p = 0.01), total gas production (p = 0.04), and concentrations of total VFA (p<0.01), propionate (p<0.01), and ammonia-N (p<0.01), with a limited 9.6% increase in IVDMD. Supplementing AnLPMO stimulated the growth of ruminal bacterial taxa facilitating fiber degradation, including Proteobacteria, Spirochaetes, Succinivibrio, Rikenellaceae_RC9_ Gut_Group, Prevotelaceae_UCG-003, Desulfovibrio, Fibrobacter succinogenes, Ruminococcus albus, R. flavefaciens, Prevotella bryantii, P. ruminicola, and Treponema bryantii. These findings highlight AnLPMO's potential as a feed additive for improving rice straw utilization in ruminant production.

Studies of the diluent, temperature and pressure effect on the lower and upper flammability limits of ammonia in air

Ammonia safety and environmental protection research forms the basis for its role as a clean energy carrier. In this work, an experimental study was conducted in this work to analyze the effect of different inhibitors (nitrogen, argon and water vapor) on the flammability limits (FLs) of ammonia at elevated temperatures and pressures. In addition, the influence of diluents on the compositions and flame temperature changes was evaluated, and the temperature sensitivity coefficients of the elementary reactions and the ROP of free radicals and partial products at the FL concentrations were analyzed. The findings indicated that water vapor provided the strongest flame retardant effect on ammonia in three inhibitors. Within a certain temperature and pressure range, the FLs of ammonia in ammonia/diluent/air can be predicted using the extended Le Chatelier equation. The flame temperature decreased at the lower flammability limit (LFL) concentrations and increased at the upper flammability limit (UFL) concentrations of ammonia with increasing initial pressure. As the initial temperature increases, the flame temperature decreases during ammonia combustion. The influence of ammonia concentration on flame temperature is greater than that of diluents dilution. The elementary reactions H+O2<=>O+OH (R1) and NH2+NO<=>NNH+OH (R82) were the primary reactions that increased the flame temperature at the FL ammonia concentrations in ammonia/diluent/air. Conversely, NH2+NO<=>N2+H2O (R80) and H+O2(+M)<=>HO2(+M)(R15) were the main reactions that decreased the flame temperature. H, OH and NH2 radicals played a crucial role in the combustion reaction process at ammonia FL concentrations. At the LFL concentrations of ammonia, the molar fraction of the OH radical showed the greatest variation, while at the UFL concentrations of ammonia it was NH2 radical. The elementary reaction NH3+OH<=>NH2+H2O (R158) was the primary reaction that consumed OH radical and promoted the formation of NH2 radical. Free radical concentrations decreased with increasing pressure and temperature, while the change rate of free radical ROP accelerated with increasing pressure. In addition to nitrogen and water, the partial products were mainly nitric oxide at the LFL concentrations, while at the UFL concentrations were mainly hydrogen.

Microalgae cultivation trials in a membrane bioreactor operated in heterotrophic, mixotrophic, and phototrophic modes using ammonium-rich wastewater: The study of fouling.

In this work, microalgae cultivation trials were carried out in a membrane bioreactor to investigate fouling when the cultures of Chlorellavulgaris were grown under mixotrophic, heterotrophic, and phototrophic cultivation regimes. The Chlorella cultures were cultivated in wastewater as a source of nutrients that contained a high concentration of ammonium. In mixotrophic cultivation trials, the results showed that the elevated contents of carbohydrates in the soluble microbial product and proteins in extracellular polymeric substances probably initiated membrane fouling. In this case, the highest protein content was also found in extracellular polymeric substances due to the high nitrogen removal rate. Consequently, transmembrane pressure significantly increased compared to the phototrophic and heterotrophic regimes. The data indicated that cake resistance was the main cause of fouling in all cultivations. Higher protein content in the cake layer made the membrane surface more hydrophobic, while carbohydrates had the opposite effect. Compared to a mixotrophic culture, a phototrophic culture had a larger cell size and higher hydrophobicity, leading to less membrane fouling. Based on our previous data, the highest ammonia removal rate was reached in the mixotrophic cultures; nevertheless, membrane fouling appeared to be the fundamental problem.

Elevated ammonia cues hatching in red-eyed treefrogs: A mechanism for escape from drying eggs.

Egg dehydration can kill terrestrial frog embryos, and this threat is increasing with climate change and deforestation. In several lineages that independently evolved terrestrial eggs, and retained aquatic tadpoles, embryos accelerate hatching to escape from drying eggs, entering the water earlier and less developed. However, the cues that stimulate drying-induced early hatching are unknown. Ammonia is a toxic, water-soluble metabolic waste that accumulates within eggs as embryos develop and concentrates as eggs dehydrate. Thus, increasing ammonia concentration may be a direct threat to embryos in drying eggs. We hypothesized that it could serve as a cue, stimulating embryos to hatch and escape. The embryos of red-eyed treefrogs, Agalychnis callidryas, hatch early to escape from many threats, including dehydration, and are known to use mechanosensory, hypoxia, and light cues. To test if they also use high ammonia as a cue to hatch, we exposed stage-matched pairs of hatching-competent, well-hydrated sibling embryos to ammonia and control solutions in shallow water baths and recorded their behavior. Control embryos remained unhatched while ammonia-exposed embryos showed a rapid, strong hatching response; 95% hatched, on average in under 15 min. This demonstrates that elevated ammonia can serve as a hatching cue for A. callidryas embryos. This finding is a key step in understanding the mechanisms that enable terrestrial frog embryos to escape from egg drying, opening new possibilities for integrative and comparative studies on this growing threat.

80 Substitution of dried distiller’s grains with soybean meal on beef cattle diets: Effects on ruminal ammonia and volatile fatty acid concentrations

Abstract The objective of this study was to evaluate the effects of substitution of dried distiller grains with soybean meal on beef cattle diets in ruminal ammonia and volatile fatty acid (VFA) concentrations. Red Angus steers [n = 4; body weight (BW) = 360 ± 9 kg] with ruminal, duodenal, and ileal cannulas, were used in a 4 × 4 latin square. Diets (TMR) consisted of dry-rolled corn (70%), hay (10%), liquid supplement (5%), and test ingredients (15%). Treatments were [dry matter (DM) basis]: 1) 15.0% DDGS (CON); SBM in replacement of 50% of DDGS (SBM50); SBM in replacement of 75% of DDGS (SBM75), and SBM in replacement of 100% of DDGS (SBM100). Each period lasted 18-d, consisting of a 7-d diet adaptation followed by an 11-d collection period. Rumen fluid was collected at -2, 0, 2, 4, 6, 8, 10, and 12 h post-feeding on d 16. Ruminal digesta was strained through two layers of cheesecloth and two 10-mL aliquots of ruminal fluid were collected and stored at −20°C until further analysis of ammonia and VFA concentrations. Data were analyzed as repeated measures using the MIXED procedure of SAS with treatment, sampling time, and their interaction as fixed effects, and animal and period as random effects. No treatment by day interactions (P ≥ 0.84) were observed for ammonia or VFA. Ammonia concentrations were greater (P ≤ 0.01) for SBM75 compared with SBM100 and CON, with intermediate values observed for SBM50 (Table 1). Moreover, ammonia was greater (P ≤ 0.01) at 0h compared with 6, 8, and 12h post-feeding. Acetate was greater (P ≤ 0.01) for SBM75 and SBM100 compared with CON and SBM50. Concentrations of propionate were greatest (P ≤ 0.01) for SBM100 and least for CON, with SBM50 and SBM75 being intermediate. Further, propionate was greater (P ≤ 0.01) at 16h compared with 0 and 2 h post-feeding, with all other times being intermediate. Isobutyrate was less (P ≤ 0.01) for CON than all other treatments, and greater concentrations (P ≤ 0.01) were observed at -2 compared with 14 and 16 h post-feeding. Butyrate was greatest (P ≤ 0.01) in SBM75, followed by CON and SBM50; SBM50 was similar to SBM100. Butyrate concentrations were similar -2 and 0 h post feeding, which were less (P ≤ 0.01) than all other times. Isovalerate was greater (P ≤ 0.01) for CON than SBM50 and SBM75, and similar to SBM100. Valerate was greatest (P ≤ 0.01) for SBM75 and SBM100 followed by SBM 50 and CON which had the least valerate value. Overall, our results show that SBM75 resulted in greater concentrations of ammonia, acetate, propionate, butyrate, isobutyrate, and valerate compared with CON. These data suggest that 75% substitution of DDGS with SBM has the potential to optimize microbial fermentation. To complement these results, we are currently evaluating rumen protein degradation profiles and amino acid flow to small intestine.

PSI-12 Dietary isoacids modulate nutrient digestibility and fermentation products in ileal digesta and feces of growing pigs fed corn-soybean meal diets

Abstract Branched-chain fatty acids, or isoacids, are the product of branched-chain amino acid fermentation and have been associated with benefits on the productivity of ruminants, primarily by positively modulating gut microbes and promoting gastrointestinal health. The objective of this study was to determine the optimal inclusion level of isoacid blend product based on apparent ileal digestibility (AID), apparent total tract digestibility (ATTD) of nutrients, and fermentation products in growing pigs fed corn-soybean meal diets. Twelve cannulated pigs [body weight (BW) = 20.9 + 0.6 kg] were used in a 5-period switch-back design with 6 diets and 2 replicate pigs in each period (n = 10 observations per dietary treatment). Experimental diets consisted of increasing levels (0%, 0.5%, 0.75%, 1%, 1.25%, and 1.5%) of an isoacid blend (isobutyrate, isovalerate, and 2-methyl butyrate, 1:1:1) added to a corn-soybean meal basal diet containing titanium dioxide as an indigestible marker. Each experimental period lasted 14 d: 10 d for acclimatization to the diets, 2 d for fecal collection, and 2 d for digesta collection. Diets, fecal, and ileal digesta samples were analyzed for gross energy (GE), crude protein (CP), fiber composition, amino acids (AA), and titanium. The concentration of short-chain fatty acids and ammonia were analyzed in digesta and fecal samples. Orthogonal polynomial contrasts were used to determine the linear and quadratic effects of increasing levels of isoacids. Dietary supplementation of isoacids improved (P &amp;lt; 0.1, linear and/or quadratic) AID of crude fiber and hemicellulose and most of the indispensable AA (except Met+Cys, Trp, and Val) as well as ATTD of CP, GE, neutral detergent fiber, and hemicellulose. In addition, ATTD of Arg, His, Ile, Leu, Met+Cys, Phe, Thr, Trp, and Val increased quadratically (P &amp;lt; 0.1). Collectively, 1% isoacid inclusion promoted the greatest responses in most measured variables (% increase: unsupplemented vs. 1%): AID of Lys (9.3%), Met (5.7%), Thr (17.8%), Leu (7.4%), Ile (9.2%), Phe (7.8%), His (5.9%), Arg (4.9%); ATTD of CP (2.1%), GE (1.3%), NDF (3.9%), hemicellulose (&amp;gt;50%), overall indispensable AA (9.5%), overall dispensable AA (8.6%). On the other hand, the inclusion of isoacids quadratically increased (P = 0.071) the concentration of ammonia and decreased (P &amp;lt; 0.1) the concentration of acetic acid, iso-valeric acid, and total VFA in ileal digesta samples. In fecal samples, the proportion of acetic acid decreased (P &amp;lt; 0.05) quadratically while the proportion of propionic, valeric, and caproic acids increased (P &amp;lt; 0.1). In conclusion, dietary supplementation of isoacids at 1% can improve dietary nutrient digestibility, particularly ileal AA digestibility. Based on the changes in fermentation products, the modulation of intestinal microbiota through the gastrointestinal tract could be potentially related to the effects of isoacids on nutrient digestibility. However, the effects of isoacids supplementation on intestinal microbiota must be determined.

84 Evaluating the effects of hind gut acidosis in sheep on rumen fermentation ex vivo

Abstract The objective was to determine the effect of hindgut acidosis in sheep on rumen fermentation ex vivo. Eleven ruminally and cecally cannulated ewes [body weight (BW) = 49 ± 4 kg] were assigned to one of two treatments: a constant infusion of deionized water (CON; 26 mL/kg BW per 24 h) or starch solution (STA; 3 g wheat starch/kg BW per 24 h) in the cecum to induce hindgut acidosis. Rumen fluid was collected from each ewe on the d before and four d after the start of cecal infusion for an ex vivo fermentation. There were four flasks for each ewe with two flasks per substrate. The two substrates were forage-based (FB; 40% grass hay pellet, 35% whole shell corn, 15% dried distiller’s grain, and 10% alfalfa cubes) and concentrate-based (CB; 75% whole shell corn, 15% dried distiller’s grain, and 10% alfalfa cubes). Flasks contained 2.5 grams of substrate and 150 mL of inoculum (2:1 ratio of McDougall’s buffer and rumen fluid). Four sealed ANKOM F57 bags were filled with 0.25g DM of substrate and placed into flasks to determine in vitro dry matter disappearance (IVDMD). The flasks were incubated at 39°C for 24 h, with sample aliquots collected at h 0, 8, and 24 to determine pH, volatile fatty acids (VFA), and ammonia. Data were analyzed using the MIXED procedure of SAS 9.4. For all response variables, values from the run before cecal infusion initiation were included in the model as a covariate. Ammonia, pH, and VFA were analyzed with the effects of treatment, time, and their interaction. For the CB substrate, there was no effect (P = 0.90) of cecal infusion on ammonia concentration; however, there was a time effect (P = 0.01) with h 24 having a greater ammonia concentration than h 8. For the FB substrate, there was a tendency for STA to have lesser (P = 0.10) ammonia than CON. There was no effect (P ≥ 0.78) of cecal infusion treatment on pH for both substrates; however, there was a time effect (P = 0.01) with pH decreasing over time. In both substrates, there were no effects (P ≥ 0.23) of cecal infusion treatment on IVDMD, VFA concentration, acetate, or propionate molar concentration. However, butyrate molar concentration tended to be less (P = 0.07) for STA ewes for the CB substrate. No treatment differences were observed in butyrate for the FB substrate (P = 0.35). Results indicate that induced hindgut acidosis in sheep did not affect rumen fermentation ex vivo.

64 Effect of feeding intact protein from soybean meal instead of crystalline amino acids on growth performance, protein synthesis, and immune response of growing pigs

Abstract The objective was to test the hypothesis that feeding intact protein from soybean meal (SBM) instead of crystalline amino acids (AA) does not affect growth performance, protein synthesis, intestinal morphology, or immune response of growing pigs. A control corn-SBM diet was used. Three additional diets were formulated by reducing the inclusion rate of SBM and adding 3, 4, or 5 crystalline AA (i.e., Lys, Met, Thr, Trp, Val) to the diets, which resulted in reducing the protein concentration from 20.0% to 13.4%. All diets were formulated to meet requirements for standardized ileal digestible indispensable AA. A total of 176 pigs [initial body weight (BW) = 32.2 kg; SD = 4.2] were used. On d 1, 16 randomly chosen pigs were euthanized and body nutrient composition was determined. The remaining 160 pigs were allotted to the 4 diets using a randomized complete block design with 4 pigs per pen and 10 replicate pens per diet. Starting BW was the blocking factor. Individual pig BW and feed consumption were recorded. On d 28, one pig per pen was slaughtered and blood, carcass, and viscera were collected and analyzed for N, fat, and energy to calculate deposition in the body. Ileal mucosa, ileum and colon tissue and digesta were analyzed for blood characteristics, cytokines, tissue morphology, ammonia, and gene expression. Contrasts coefficients were used to determine linear and quadratic effects of reducing dietary protein. Results indicated that average daily gain, average daily feed intake, gain to feed ratio, carcass characteristics, and protein, lipid, and energy depositions were not affected by reducing SBM and increasing crystalline AA in diets (Table 1). However, energy efficiency tended to decrease (quadratic, P = 0.083) by reducing dietary protein. Blood urea N was reduced (linear, P &amp;lt; 0.001) as dietary protein was reduced, but blood total protein was not affected by dietary treatment. Cytokines, ileal and jejunal morphologies, and gene abundance of AA transporters in the ileal mucosa were not affected by dietary protein. Ammonia concentrations in ileal digesta increased and then decreased (quadratic, P = 0.043) and colon digesta tended to increase and then decrease (quadratic, P = 0.074) as dietary protein was reduced. Bacteria protein in colon digesta was reduced (linear, P = 0.030) by reducing dietary protein. In conclusion, providing AA from intact protein from SBM or from crystalline AA did not affect growth performance, intestinal morphology, and immune response of pigs. However, SBM in diets can provide energy that may be utilized more efficiently than energy from diets with less SBM and crystalline AA. Further research is suggested to elucidate if SBM improves utilization of other nutrients in diets for pigs.

PSVI-4 Effects of ruminal acidosis on rumen fermentation of steers adapted to a high concentrate diet

Abstract The objective was to characterize the effects of ruminal acidosis on rumen fermentation of steers adapted to a high concentrate diet. Cattle entering the feedlot undergo a transition period where the amount of concentrates in the diet is gradually increased to mitigate the risks of ruminal acidosis. Despite a dietary adaptation, rumen acidosis still affects feedlot cattle later in the finishing phase. Ruminally cannulated steers [n = 11; body weight (BW) = 795 kg ± 54) were blocked into 2 groups based on initial BW. Before the start of the study, cattle had been consuming a finishing diet (60% dry rolled corn, 15% modified distiller’s grains, 15% corn silage, and 10% ground corn based supplement) for more than 150 d. Steers were randomly assigned to 1 of 2 treatments: control (CON) or acidosis (ACD). For the experiment, steers were fasted for 24 h and at the conclusion received the same finishing diet. Steers on ACD steers were also ruminally dosed 0.05% BW of wheat starch on h 0 and h 12 to induce acidosis. Rumen fluid was collected every 4 h for 48 h to analyze ruminal pH, ammonia, volatile fatty acids (VFA), and lactate. Fecal grab samples were collected every 8 h for 48 h to determine fecal pH. Data were analyzed with the MIXED procedure of SAS 9.4 with the effects of treatment, time, and their interaction. A treatment × hour (P &amp;lt; 0.01) effect was observed for ruminal pH with the ACD steers having a lower pH than CON from h 12 to 32. Fecal pH was not affected by treatment, time, or their interaction (P ≥ 0.12). Steers fed ACD had greater total VFA concentration than CON (P &amp;lt; 0.01). A treatment × hour interaction (P &amp;lt; 0.01) was observed for acetate molar proportion with CON having greater percentage acetate at h 24 through 32. Additionally, there was a treatment × hour interaction (P &amp;lt; 0.01) for propionate molar proportion with ACD steers having greater propionate at h 28 and 32, and then at h 40 and 44. Butyrate was not affected (P ≥ 0.58) by treatment × hour or treatment. Acetate to propionate ratio (A:P) was affected by treatment × hour (P &amp;lt; 0.01) with CON steers having greater A:P after h 28. Rumen ammonia and lactate concentrations did not differ (P ≥ 0.25) by treatment or the interaction with h. In steers adapted to a high concentrate diet, acidosis only altered ruminal fermentation in regards to ruminal pH and VFA concentrations.

PSVI-5 Extruded blend of Nannochloropsis oculata microalgae and flaxseed and its effects on ruminal fermentation and nutrient digestion

Abstract Omega-3 fatty acids are essential nutrients for mammals, and are required for cellular growth and synthesis of numerous cellular signaling molecules. NBO3 Technologies, LLC (Manhattan, KS) has developed an omega-3 supplement consisting of an extruded blend of flaxseed and Nannochloropsis oculata microalgae (GreatOplus; GOP). Our objective was to evaluate effects of GOP on dry matter intake (DMI), water intake (WI), ruminal metabolism, and apparent total tract nutrient disappearance in cannulated Holstein steers (n = 11; initial body weight 586.4 ± 49.7 kg). Treatments consisted of backgrounding diets (40% roughage, 60% concentrate) containing 0% (CON) or 10% GOP (dry basis). Feed and water intake were recorded using an Insentec Roughage and Water monitoring system (Hokofarm Group; Emmeloord, The Netherlands). Steers were utilized in a cross-over design with two 19-d periods. Each period consisted of a 15-d adaptation phase and a 4-d collection phase. Ruminal contents, duodenal digesta, and feces were collected at 8-h intervals for 4 d starting at 1000 h on d 16. The sampling schedule was advanced by 2 h with each subsequent sampling day, thus generating a 24-h profile at 2-h intervals post-feeding over the 4-d sampling phase. Titanium dioxide (15 g) was dispensed directly into the rumen of each steer 15 min before feeding and to estimate apparent ruminal flow and fecal excretion of nutrients. There was a Treatment X Day interaction for DMI (P &amp;lt; 0.001); DMI was greater for steers fed GOP some of the days during the adaptation phase compared with steers fed the control diet, but intakes were similar during the collection phase. Ruminal fluid pH, ruminal ammonia concentration, and WI were not affected by treatment (P &amp;gt; 0.10). As expected, ruminal outflows of total fatty acids (195.6 vs 338.1 g/d for CON and GOP, respectively) and α-linolenic acid (ALA; 1.6 vs 6.3 g/d, respectively) were greater for steers fed GOP compared with steers fed CON (P &amp;lt; 0.05); however, ruminal disappearance (i.e., biohydrogenation) of ALA was extensive, with only 8% and 4.7% of ALA intake exiting the rumen for CON and GOP, respectively. Apparent total tract digestion of organic matter was not impacted by diet (P &amp;gt; 0.20; 78.1 and 76.8% for CON and GOP, respectively). Supplementing an extruded blend of flaxseed and microalgae can effectively increase the amount of α-linolenic acid available for absorption in the small intestine, but overall recovery of dietary α-linolenic acid is relatively low due to extensive biohydrogenation by microbes within the rumen.

Use of eggshell as an alternative substrate for biofilters in recirculation aquaculture systems

One of the biggest challenges of recirculating systems (RAS) is keeping levels of toxic compounds, such as ammonia, low. This work sought to evaluate the use of eggshell as a biofilter substrate in the cultivation of juvenile Oreochromis niloticus. The experiment lasted 90 days, using four treatments: A) 100% expanded clay, A+CO) 50% expanded clay and 50% eggshell, PC) MBBR3 and NC) without substrate, with three replications each, storing 15 juveniles with an initial weight of 1.26±0.08g. Feeding occurred three times a day with commercial food offered until apparent satiety. The following parameters were monitored: pH, temperature (ºC), dissolved oxygen (mg L-1), electrical conductivity (µS cm-1) and total soluble solids (ppm); and zootechnical performance indices: survival rate (%), weight gain (g), specific growth rate (% day-1) and condition factor. Water samples were collected at the inlet and outlet of the biofilters on days 0, 30 and 60 of the experiment. Means were compared using the 5% Tukey test. All biofilters used maintained water quality parameters within those recommended for production, with emphasis on A+CO. The concentrations of ammonia at the inlet of the A+CO biofilter were lower than the others, providing lower levels of this substance in the system and high concentrations of nitrate. It was concluded that the biofilter composed of 50% expanded clay and 50% eggshell showed better efficiency in maintaining water quality compared to the others, revealing its potential as an alternative biological substrate.

Discovery of the first hydrothermal field along the 500-km-long Knipovich Ridge offshore Svalbard (the Jøtul field)

Oceanic spreading centers north of Iceland are characterized by ultraslow spreading rates, and related hydrothermal activity has been detected in the water column and at the seafloor along nearly all ridge segments. An exception is the 500-km-long Knipovich Ridge, from where, until now, no hydrothermal vents were known. Here we report the investigation of the first hydrothermal vent field of the Knipovich Ridge, which was discovered in July 2022 during expedition MSM109. The newly discovered hydrothermal field, named Jøtul hydrothermal field, is associated with the eastern bounding fault of the rift valley rather than with an axial volcanic ridge. Guided by physico-chemical anomalies in the water column, ROV investigations on the seafloor showed a wide variety of fluid escape sites, inactive and active mounds with abundant hydrothermal precipitates, and chemosynthetic organisms. Fluids with temperatures between 8 and 316 °C as well as precipitates were sampled at four vent sites. High methane, carbon dioxide, and ammonium concentrations, as well as high 87Sr/86Sr isotope ratios of the vent fluids indicate strong interaction between magma and sediments from the Svalbard continental margin. Such interactions are important for carbon mobilization at the seafloor and the carbon cycle in the ocean.

Hydrology and oxygen addition drive nutrients, metals, and methylmercury cycling in a hypereutrophic water supply reservoir

Impaired water quality in Mediterranean climate reservoirs is mainly associated with eutrophication and internal nutrient loading. To improve water quality in hypereutrophic Hodges Reservoir, California, United States, a hypolimnetic oxygenation system (HOS), using pure oxygen gas, was implemented in 2020. This study encompasses 3 years of pre-oxygenation data (2017–2019) and 2 years of post-oxygenation data (2020–2021) to understand the cycling of nutrients, metals, and mercury in the reservoir. During the wet year of 2017, mildly reduced conditions lasted until mid-summer in the enlarged reservoir. Nutrients and metals were seen in the hypolimnion including ammonia (~2 mg-N/L), manganese (~0.5 mg/L), phosphate (~0.5 mg-P/L), and sulfide (~10 mg/L). Production of methylmercury (MeHg), an important bioaccumulative toxin, was favored from April to June with a hypolimnetic accumulation rate of around 200 ng/m2·d. In contrast, the dry year of 2018 exhibited higher hypolimnetic concentrations of ammonia (~4 mg-N/L), manganese (~1 mg/L), phosphate (&amp;gt;0.5 mg-P/L), and sulfide (&amp;gt;15 mg/L). The rapid onset of highly reduced conditions in 2018 corresponded with low MeHg hypolimnetic accumulation (~50 ng/m2·d). It seems that mildly reduced conditions were associated with higher MeHg accumulation, while sulfidic, reduced conditions impaired inorganic mercury bioavailability for MeHg production and/or promoted microbial demethylation. Sulfide also appeared to act as a sink for iron via FeS precipitation, and potentially for manganese via MnS precipitation or manganese coprecipitation with FeS. Mass flux estimates for 2017–2019 indicate that much of the nutrients that accumulated in the hypolimnion moved via turbulent diffusion into the epilimnion at loading rates far exceeding thresholds predicting eutrophic conditions. After oxygenation in 2020–2021, the reservoir water column was highly oxidized but showed a lack of thermal stratification, suggesting reservoir operations in combination with HOS implementation inadvertently mixed the water column in this relatively shallow reservoir. Post-oxygenation, concentrations of ammonia, phosphate, manganese, and mercury in bottom waters all decreased, likely in response to oxidized conditions. Oxygenated bottom waters exhibited elevated nitrate, a byproduct of ammonia nitrification, and iron, a byproduct of FeS oxidation, indicating a lake-wide response to oxygenation.

Towards in-site carbon utilization and highly efficient nutrients removal: Effects of ammonium on the phosphorus recovery performance in a biofilm-based system

An alternatively anaerobic–aerobic biofilm system was operated for treating synthetic municipal wastewater for 150 days, and the effect of ammonium concentration in range of 15 mg∙L−1 - 50 mg∙L−1 on the phosphorus recovery performance was discussed. The ammonium concentration was confirmed as an important factor for balancing phosphorus accumulating organisms (PAOs) and denitrifying phosphorus-accumulating organisms (DPAOs) to affect nutrients removal and phosphorus recovery. The PAOs dominated in phosphorus removal with the ammonium less than 30 mg∙L−1, the ortho-P concentration in recovery steam was plateaued at 52 mg∙L−1. The increase in ammonium to 40 mg∙L−1 caused the seriously deterioration in PAOs activity; however, the phosphorus removal and recovery performance was decreased slightly which attributed to the vital contribution of DPAOs in phosphorus removal. The adverse effect of ammonium can be eliminated by decreasing the volume exchange ratio (VER) from 3.0 to 1.5, leading to the phosphorus concentration in recovery steam of 72.21 mg∙L−1. Meanwhile, the phosphorus removal efficiency (PRE) and total nitrogen removal efficiency (NRE) were stable at 97.8 % and 99.2 %, respectively, indicating highly efficient phosphorus recovery and nutrients removal in the biofilm system. The outcome of the present study could facilitate the establishment of an integrative technology to realize in-site carbon utilization, highly efficient nutrients removal and phosphorus recovery simultaneously in the mainstream treatment of sewage wastewater, and the study reveals the transformation pathways of P and N in the BPRR system, as well as the complex interactions between functional microorganisms.

Ammonia-enriched biogas as an alternative fuel in diesel engines: Combustion, performance and emission analysis

This study investigates the potential of ammonia as a secondary fuel in diesel engines, amidst the rising interest in alternative fuels and the growth of electric vehicles. Unlike hydrogen, with its higher flammability and safety concerns, ammonia offers a viable, sustainable fuel source. A single-cylinder diesel engine was utilized to assess engine performance and combustion characteristics using ammonia gaseous blends. Ammonia was combined with biogas to mitigate its corrosive effects and compensate for its lower heating value. Th entire best conducted with constant ammonia flow rate of 30 LPM. Diesel was mixed with biogas in compositions of 10 LPM, 20 LPM and 30 LPM, and tested under engine loads of 25%, 50%, 75%, and 100%. The blend with the highest ammonia concentration (B30B3) exhibited the largest heat release rate, highlighting a strong correlation between ammonia content and heat release levels. This is attributed to the premixed combustion phase and the accelerated flame speed associated with ammonia. An increase in ammonia content resulted in higher brake thermal efficiency and reduced brake specific fuel consumption. All ammonia-inclusive blends showed a decrease in hydrocarbon and carbon monoxide emissions, with the lowest emissions observed in the B30B3 blend. However, the high flammability of biogas in the B30B3 blend, compared to diesel, and enhanced fuel atomization, led to increased nitrogen Oxides formation. The results clearly indicate that combination of ammonia along with the biogas enhances the combustion and reduces greenhouse gas emissions. Findings of this study provides valuable insights into the use of ammonia as a sustainable alternative in diesel engines, offering a improved balance between combustion efficiency and environmental impact.