Increase In NH4 Research Articles

Recovery of ammonia assimilating microbiome after Cr (VI) shock by bio-accelerators

The pretreatment process is often unable to completely intercept heavy metals in wastewater, facing a huge risk of leakage, increasing the difficulty of treating pollutants in the subsequent biochemical process or even leading to the collapse of the system, and facing the difficulty of inoperability and rehabilitation. Heterotrophic ammonia assimilation has the potential to maintain some stability after heavy metal shock, thanks to its rapid microbial proliferation, robust resistance to high loads, remarkable environmental adaptability, and inherent stability. Bio-accelerators dosing strategies could strengthen the performance recovery ability of traditional bio-system after heavy metal impact. However, no recovery strategies for inhibiting HAA have been reported. Herein, three bio-accelerants, specifically, vitamin A, 6-benzylaminopurine, and α-ketoglutaric acid, were investigated for their potential to restore the HAA system impacted by 20 mg/L Cr (VI). The three bio-accelerants effectively mitigated the toxicity of the HAA system, resulting in a 60.4% increase in NH4+-N removal efficiency within just 6 days with cytokinin. During toxicity remediation, three bio-accelerants facilitated the production of extracellular protein components in soluble microbial products and stimulated the secretion of extracellular polymeric substances. The three bio-accelerants enhanced competition among genera and influenced community assembly processes to regulate community structure and enhance functional gene expression. This study offers a practical approach to enhancing the HAA process and remediating microbial toxicity.

Integrated electrocatalytic synthesis of ammonium nitrate from dilute NO gas on metal organic frameworks-modified gas diffusion electrodes

The electrocatalytic conversion of NO offers a promising technology for not only removing the air pollutant but also synthesizing valuable chemicals. We design an integrated-electrocatalysis cell featuring metal organic framework (MOF)-modified gas diffusion electrodes for simultaneous capture of NO and generation of NH4NO3 under low-concentration NO flow conditions. Using 2% NO gas, the modified cathode exhibits a higher NH4+ yield and Faradaic efficiency than an unmodified cathode. Notably, the modified cathode shows a twofold increase in NH4+ production with 20 ppm NO gas supply. Theoretical calculations predict favorable transfer of adsorbed NO from the adsorption layer to the catalyst layer, which is experimentally confirmed by enhanced NO mass transfer from gas to electrolyte across the modified electrode. The adsorption layer-modified anode also exhibits a higher NO3− yield for NO electro-oxidation compared to the unmodified electrode under low NO concentration flow. Among various integrated-cell configurations, a single-chamber setup produces a higher NH4NO3 yield than a double-chamber setup. Furthermore, a higher NO utilization efficiency is obtained with a single-gasline operation mode, where the NO-containing gas flows sequentially from the cathode to the anode.

Assessing the impact of rainfall on water quality in a coastal urban river utilizing the environmental fluid dynamics code

The Haihe River, flowing through Tianjin City, grapples with pollution challenges, notably high levels of nitrogen (N) and phosphorus (P) leading to eutrophication and unpleasant odors, particularly aggravated by rainfall. This study used Environmental Fluid Dynamics Code to comprehensively analyze the water environment under three scenarios: low flow year, normal flow year, and high flow year. The investigation delves into N and P concentrations, computes atmospheric deposition fluxes, and evaluates the loads and retention ratios of N and P in the urban river network of Tianjin City. Scenario analysis reveals distinct trends, with high flow years associated with elevated N and hydrodynamics levels, while low flow years exhibit contrasting patterns. Key findings include 1) wet deposition fluxes contributing 21% of NH4+-N and 9% of TP river loads, 2) continuous rainfall and runoff resulting in immediate or delayed increases in NH4+-N, TN, and TP concentrations in surface water, 3) an increase in average N:P mole ratios downstream along the Haihe River, and 4) N and P mean retention ratios were 48% and 63%, respectively. The study suggests that implementing sponge city construction and sustainable drainage systems may improve water quality by mitigating the direct discharge of rainfall runoff into the river.

Enhanced electroreduction of low-concentration nitrate using a Cu-Pd bimetallic cathode system: Performance evaluation, mechanism analysis, and potential applications

Copper (Cu) is a widely recognized cathode for the electrochemical reduction of nitrate (NO3-). Nevertheless, its practical applications are currently restricted due to limited activity and selectivity, particularly at low NO3- concentrations. Herein, a Cu-Pd bimetallic cathode system was designed for NO3- reduction reaction with low NO3- concentrations (≤40 mg-N L−1). In this system, a Cu nanowire array cathode was utilized for NO3- reduction, while a Pd/C particle cathode was employed for NO2- reduction with H2 generated in situ from a polypyrrole electrode. Due to the improved mass transfer and active sites derived from Pd/C particle cathode, along with the synergistic effects of NO3- reduction and NO2- reduction, the constructed Cu-Pd bimetallic cathode system achieved a 7.32-fold increase in NO3– removal rate and a 1.70-fold increase in NH4+ selectivity compared to the traditional Cu cathode. This performance surpassed that of many other state-of-the-art Cu-based cathodes under similar conditions. Moreover, the Cu-Pd bimetallic cathode system displayed high reusability, and extremely low Cu and Pd leaching. Additionally, it showed strong resistance to environmental factors and can adapt to a wide pH range (3−9) and various NO3- concentrations (10–40 mg-N L−1). The electron spin resonance and scavenger experiments confirmed that both direct electron transfer and indirect reduction by atomic H* were involved in the NO3- removal process, with indirect reduction playing a more significant role. Overall, our findings guide the design of superior catalytic systems for NO3- removal to enhance the activity and selectivity of NO3- reduction for efficient water purification.

Localized nitrogen supply facilitates rice yield and nitrogen use efficiency by enabling root-zone nitrogen distribution and root growth

IntroductionLocalized nitrogen (N) supply affects rice N uptake by influencing N release, and few studies have examined the effects of root zone N distribution and root growth on rice yield under localized N supply (LNS).MethodsA two-year field experiment was conducted with six treatments: no N application, farmers’ fertilizer practice (FFP), and four LNS treatments, including two types of N fertilizer with urea (U) and controlled release urea (CRU) were mechanically side deep fertilized (SDF) or root zone fertilized (RZF) at 10 cm soil depth (US, UR, CRUS and CRUR treatments, respectively).ResultsCompared with FFP, the dry matter accumulation, N uptake, and yield of LNS increased by 27%, 21%, and 17%, respectively. For N fertilizer type, compared with U, the NH4+-N concentration, total root surface area, volume, average diameter, and root biomass of CRU were significantly increased by 50%, 43%, 53%, and 23%, respectively, which resulted in a significant increase in yield by 12%. Regarding the N application methods, the total surface area, volume, average diameter, and root biomass of SDF were significantly increased by 32%, 24%, 10%, and 25% compared with RZF, respectively. However, the NH4+-N under RZF was more stable and lasted longer, with a significant increase in NH4+-N concentration of 21% compared to the SDF. Moreover, CRUR increased yield, N agronomic use efficiency, and gross return by 3.15%, 5.62%, and 2.81%, respectively, compared to CRUS.ConclusionCRU should be selected as the recommended N fertilizer types, and the combination of CRU and RZF was the most effective choice for rice production.

Impact of Paddy Straw Incorporation along with Different Fertilizer Doses on Mineral N Dynamics and GHG Emissions

Aim: An incubation experiment was conducted, which aimed to investigate NH4+ and NO3- release pattern and GHG emissions as influenced by paddy residue decomposition over 120 days. Study Design: Completely randomized block design. Place and Duration of Study: The study was conducted at Agrometerology laboratory, CRIDA, Hyderabad. The experiment was conducted between 2021-22. Methodology: Sampling was performed at 2, 4, 6, 8, 10, 20, 30, 45, 60, 75, 90, 105 and 120 days after incubation (DAI). The treatments included control (T1), soil + N (T2), paddy residue + 100% RDN (Recommended dose of Nitrogen) - 33:33:33 (T3), paddy residue + 100% RDN - 43:23:33 (T4), paddy residue + 100% RDN - 43:33:23 (T5), paddy residue + 10% extra RDN - 43:23:33 (T6). Fertilizer N was applied in three splits (first at initiation of experiment, second and third at 30 and 60 DAI respectively). RDN used in the study was 240 kg ha-1 (i.e., maize). Results: Residue incorporation along with inorganic fertilizer significantly influenced NH4+ - N and NO3- - N, as well as GHG emissions. After addition of each split, there was an increase in NH4+ - N and NO3- - N contents. Significantly higher NH4+ - N and NO3- - N was recorded in T6, compared to other treatments. The cumulative CO2 and N2O emissions were significantly higher in paddy residue + 10 % extra RDN – 43:23:33 i.e., 296.63 µg C g-1 of soil and 1.81 µg N g-1 of soil respectively, while lowest (42.59 µg C g-1 of soil and 0.09 µg N g-1 of soil respectively) was observed in control.

Interspecific variations in growth, physiology and Cd accumulation between Populus deltoides and P. × canadensis in response to Cd pollution under two soil types

Both acid and alkaline purple soils in China are increasingly affected by Cd contamination. The selection of fast-growing trees suitable for remediating different soil types is urgent, yet there is a severe lack of relevant knowledge. In this study, we conducted a controlled pot experiment to compare the growth, physiology, and Cd accumulation efficiency of two widely recognized poplar species, namely Populus deltoides and P. × canadensis, under Cd contamination (1 mg kg−1) in acid and alkaline purple soils. The objective was to determine which poplar species is best suited for remediating different soil types. Our findings are as follows: (1) the total biomass of both poplars remained largely unaffected by Cd pollution in both soil types. Notably, under Cd pollution, the total biomass of P. deltoides in acid purple soil was 1.53 times greater than that in alkaline purple soil. (2) Cd pollution did not significantly induce oxidative damage in the leaves of either poplar species in both soil types. However, in acid purple soil, Cd contamination led to a 21% increase in NO3- concentration and a 44% increase in NH4+ concentration in P. × canadensis leaves, whereas in alkaline purple soil, it led to a 59% increase in NH4+ concentration in P. deltoides leaves. (3) Cd concentrations in all root orders of P. × canadensis were significantly higher than those in P. deltoides, especially in the first three root orders, under alkaline purple soil. The total Cd accumulation by P. × canadensis in Cd-polluted alkaline purple soil was 2.18 times higher than that in Cd-polluted acid purple soil, a difference not observed in P. deltoides. (4) redundancy analysis indicated that the sequestration effect of higher soil organic matter on Cd availability in acid purple soil was more pronounced than the release effects caused by lower pH. In conclusion, P. × canadensis is better suited for remediating alkaline purple soil due to its higher capacity for Cd uptake, while P. deltoides is more suitable for remediating Cd-contaminated acid purple soil due to its better growth conditions and greater Cd enrichment capability.

Nitrogen and carbon cycling and relationships to radium behavior in porewater and surface water: Insight from a dry year sampling in a hypersaline estuary

Biogeochemical transformations within highly saline subterranean estuaries (STE) dramatically affect solute cycling, resulting in submarine groundwater discharge (SGD) with distinct chemical signatures. The study hypothesizes that biogeochemical processes within hypersaline bay porewaters (PW) simultaneously affect nitrogen, carbon, and radium cycling. We measured radium isotopes (226Ra, 224Ra, and 223Ra), nutrients (dissolved inorganic nitrogen [DIN: NH4+ + NO2− + NO3−], HPO42− [DIP], HSiO3− [DSi], dissolved organic carbon [DOC]), total alkalinity (TA), dissolved inorganic carbon (DIC), stable isotopes, and major cations in PW and surface water (SW) of Baffin Bay, a well-mixed, semi-enclosed estuary along the semiarid northwestern Gulf of Mexico coast, over three seasons in a characteristically dry year. This study's findings show a concurrent increase in NH4+, DIP, DSi, and TA/DIC with reduced metal species (e.g., Mn and Fe) and Ra during the hot and dry seasons, particularly in PW, under increasingly reducing conditions. Principal component analyses (PCA) suggest these increases are primarily driven by dissimilatory nitrate/nitrite reduction to ammonium (DNRA) and dissolution of lithogenic particles and biogenic CaCO3, modulated by organic matter degradation or remineralization. While more significant terrestrial groundwater inputs may contribute to solutes and Ra supply in the STE, the biogeochemically induced variability in solute concentrations in PW primarily drives larger SGD-derived fluxes, particularly notable in hot months. During a typically dry year, these fluxes, estimated as the average of 226Ra and 223Ra mass balance models (e.g., July/November fluxes in Mmol∙d−1: 0.093/0.092 of NO3−; 0.2/0.02 of NO2−; 72/16 of NH4+; 72.2/18 of DIN; 1.5/0.2 of HPO42−; 20/9 of HSiO3−; 42/37 of DOC; 503/399 of TA; 582/431 of DIC) are orders of magnitude (∼4 for DIN and DIC, ∼3 for DIP, DSi, and DOC, and ∼2 for TA) greater than surface runoff inputs. These substantial SGD inputs likely sustain phytoplankton growth and potentially fuel harmful algal blooms while countering estuarine acidification.

Study on the effectiveness and mechanism of a sustainable dual slow-release model to improve N utilization efficiency and reduce N pollution in black soil

Long-term intensive cultivation has led to serious N loss and low N fertilizer utilization efficiency (NUE) in black soil areas. The lost N is not only a waste of resources but also a serious pollution threat to the environment, leading to the decline in water quality and food safety and the greenhouse effect. In the present study, a stable dual slow-release model, CPCS-Urea, was prepared by in situ polymerization using nitrapyrin, urea and melamine-formaldehyde resin as raw materials. The effect of the dual slow-release model was systematically evaluated using two consecutive years of field experiments. Five treatments were established in the field experiment: no N fertilizer (N0), urea (N180), 1 % CPEC-Urea, 0.5 % CPCS-Urea, and 1 % CPCS-Urea. The results showed that the new dual slow-release CPCS-Urea model outperformed both the use of urea and the traditional slow-release CPEC-Urea model in reducing N losses and improving NUE. The application of CPCS-Urea reduced nitrate (NO3−) leaching by 28.2 %–47.2 % and N2O emissions by 36.5 %–42.4 % and increased NUE by 20.7 %–28.5 % compared to urea application. The CPCS-Urea model modulated the activity of ammonia-oxidizing bacteria (AOB) and dissimilatory nitrate reduction to ammonium (DNRA) bacteria in soil, showing a significant decrease in AOB activity and an increase in DNRA activity. This results in a lower soil NO3−-N yield and a 53.1 %–72.0 % increase in NH4+-N content, providing sufficient N for the entire growth and development cycle of maize. In short, the dual slow-release CPCS-Urea model has great application prospects for promoting agricultural development in black soil areas.

Impacts of an extreme Changjiang flood on variations in carbon cycle components in the Changjiang Estuary and adjacent East China sea

River flooding is expected to increase in frequency and severity under climate change. However, the impact of extreme river flooding on the coastal carbon cycle has rarely been studied. A severe Changjiang flood occurred in the summer of 2020, which was the largest Changjiang flood in the last 20 years since 2000. This extreme flood resulted in the export of great amounts of nitrate (6.4 × 108 mol d−1), silicate (7.1 × 108 mol d−1), phosphate (5.1 × 106 mol d−1), dissolved organic carbon (DOC; 13.9 × 109 g C d−1), and inorganic carbon (DIC; 145.5 × 109 g C d−1) from Changjiang to the Changjiang Estuary, which were considerably higher (by ∼8–178%) compared to those observed in previous summers since 2006. The increase in nutrient loads, including a considerable increase in PO43− concentrations due to the flood, has triggered the development of severe algal blooms in the East China Sea. Consequently, the production of DOC and removal of DIC were observed in the offshore region during the flood. Moreover, the increase in NH4+ concentrations likely indicated enhanced organic material remineralization in flood-influenced coastal waters. The decrease in CO2 fluxes across the air-sea interface (FCO2) has been observed in the offshore region, while an increase in FCO2 was found in the nearshore region during the flood compared to the non-flood condition in July 2018. These findings provide valuable references for assessing the impact of the extreme Changjiang flood on the coastal carbon cycle.

Salinity and nitrogen source affect productivity and nutritional value of edible halophytes.

Saline agriculture may contribute to food production in the face of the declining availability of fresh water and an expanding area of salinized soils worldwide. However, there is currently little known about the biomass and nutrient/antinutrient accumulation response of many edible halophytes to increasing levels of salinity and nitrogen source. To address this, two glass house experiments were carried out. The first to study the shoot biomass, and nutrient accumulation response, measured by ICP-MS analysis, of edible halophyte species, including Mesembryanthemum crystallinum (ice plant), Salsola komarovii (Land seaweed), Enchylaena tomentosa (Ruby Saltbush), Crithmum maritimum (Rock Samphire), Crambe maritima (Sea Kale) and Mertensia maritima (Oyster Plant), under increasing levels of salinity (0 to 800 mM). The second experiment studied the effects of nitrogen source combined with salinity, on levels of oxalate, measured by HPLC, in ice plant and ruby saltbush. Species differences for biomass and sodium (Na), potassium (K), chloride (Cl), nitrogen (N) and phosphorus (P) accumulation were observed across the range of salt treatments (0 to 800mM). Shoot concentrations of the anti-nutrient oxalate decreased significantly in ice plant and ruby saltbush with an increase in the proportion of N provided as NH4+ (up to 100%), while shoot oxalate concentrations in ice plant and ruby saltbush grown in the absence of NaCl were not significantly different to oxalate concentrations in plants treated with 200 mM or 400 mM NaCl. However, the lower shoot oxalate concentrations observed with the increase in NH4+ came with concurrent reductions in shoot biomass. Results suggest that there will need to be a calculated tradeoff between oxalate levels and biomass when growing these plants for commercial purposes.

Dissolved organic carbon bioreactivity and DOC:DIN stoichiometry control ammonium uptake in an intermittent Mediterranean stream

Abstract Heterotrophic organisms in streams use dissolved organic carbon (DOC) and dissolved inorganic nitrogen (DIN) from the water column to meet their growth and energy requirements. However, the role of DOC availability in driving DIN uptake in headwater streams is still poorly understood. In this study, we focus on how DOC:DIN stoichiometry and DOC bioreactivity control ammonium (NH4+) uptake and heterotrophic aerobic respiration, and how this influence varies among seasons in a forested Mediterranean headwater stream. We estimated in‐stream NH4+ uptake rates seasonally by conducting whole‐reach constant‐rate additions of NH4+ with and without amendments of either lignin (recalcitrant DOC) or acetate (labile DOC). During each addition, we characterised microbial community composition by molecular analyses, stream metabolism with the single‐station method, and heterotrophic aerobic respiration by adding a metabolic tracer (resazurin). The stream was heterotrophic (net ecosystem production <0) regardless of the season, with a microbial community mostly composed of heterotrophic bacteria. In‐stream NH4+ uptake rates were not related to either background NH4+ or DOC concentrations. Instead, these rates increased with increasing the molar ratio of NH4+ to nitrate (NO3−) (NH4+:NO3−) and DOC to DIN (DOC:DIN).Whole‐reach heterotrophic aerobic respiration rates showed the same relationship against stoichiometric ratios as NH4+ uptake rates. Furthermore, in‐stream NH4+ uptake rates were from 5% to >800% higher during the co‐additions of acetate than when adding NH4+ either alone or with lignin. Our results indicate that in‐stream NH4+ uptake was largely controlled by heterotrophic bacteria, and that the stoichiometric balance between organic resources and nutrients was key to explaining the variability of in‐stream NH4+ uptake and heterotrophic aerobic respiration. Moreover, the observed increase in NH4+ uptake during acetate additions suggests that heterotrophic activity was limited by labile DOC availability. Our study highlights that both DOC:DIN stoichiometry and DOC bioreactivity are relevant factors driving the seasonal pattern of in‐stream N processing in this forested Mediterranean headwater stream.

P8: A Coated ZrP Cation Exchanger with Excellent Ammonium Selectivity and Chemical Stability: An Oral Sorbent for End-Stage Kidney Disease (ESKD)

A sorbent with high enough capacity for NH4+ could serve as an oral binder to lower urea levels in end-stage kidney disease patients (Figure 1). A hydrogen-loaded cation exchanger such as zirconium phosphate (ZrP) is a promising candidate for this application. However, the NH4+ binding selectivity versus other ions must be improved. A gas-permeable and hydrophobic surface coating was first attached to an amorphous form of ZrP using tetraethyl orthosilicate and methoxy-terminated polydimethylsiloxane (PDMS). The coating prevents ions in solution from reaching the ion-exchanger but allows NH3 transfer to the ZrP. The selectivity of the coating was measured with NH4+ and Ca2+ solutions versus uncoated ZrP. X-ray photoelectron spectroscopy and scanning electron microscopy measurements showed the coating successfully modified the surface of ZrP. Water contact angle (WCA) studies indicated coated ZrP was hydrophobic (149.8° ± 2.5°). The in vitro studies showed coated ZrP removed 94% (± 11%) more NH4+ than uncoated ZrP in the presence of Ca2+. And Ca2+ binding decreased by 64% (± 6%). The increase in NH4+ selectivity was due to the applied coating. But the material’s selectivity decreased by 72% after exposure to stomach acid conditions. An alternative hydrophobic (WCA = 145.0° ± 3.2°) and gas permeable coating was investigated – perfluorooctyltriethoxysilane (FOTS). The coating was attached to a polysiloxane membrane on ZrP’s surface. In vitro studies in Figure 2b indicated the FOTS structure attached to ZrP offers complete selectivity for NH4+ over Ca2+ with similar NH4+ capacity as the PDMS coating. FOTS-coated ZrP maintained its selectivity and NH4+ removal capacity after stomach acid exposure. The results indicate FOTS-coated ZrP could work as an oral sorbent for ESKD patients.Figure 1. The recirculation of urea and oral sorbent’s methodology for NH4+ adsorption. Figure has been adapted from Barret’s original artwork.1Figure 2. (a): SEM images of uncoated, PDMS-coated and FOTS-coated ZrP at 10,000x magnification. (b): Binding study results of uncoated, PDMS-coated and FOTS-coated ZrP.

Influence of bicarbonate, other anions and carbon dioxide in the activity of Pd-Cu catalysts for nitrate reduction in drinking water

Synthetic and commercial drinking waters with different composition were studied as reaction media to study the influence of salts in NO3- catalytic reduction using a Pd-Cu catalyst supported on a carbon black. As a general trend, a decrease in NO3- conversion and an increase in NH4+ selectivity were observed for high HCO3- concentration media in mixed salts waters. Literature has commonly ascribed HCO3- effect to competitive adsorption with NO3-. However, in the current work, the mechanism for effect HCO3- is reconsidered basis on HCO2- formation during NO3- catalytic reduction, here reported for the first time. HCO2- formation indicates that hydrogenation of HCO3- occurs in addition to adsorption. Likewise, decomposition of HCO2- on the catalysts surface releases hydrogen leading to increased spill-over and relevant hydrogenation of NO3- to NH4+. The presence of SO42-, Cl- reduces NH4+ selectivity due to competition for active sites and lower HCO2- generation. Furthermore, it was observed that the use of CO2 as buffer also contribute to the hydrogenation of NO3- to NH4+ through HCO2- route.

Soil nitrification process played a key role in alleviating continuous cropping limitation induced by fumigation

Continuous cropping causes enormous crop produce reduction, and soil fumigation is an effective approach to alleviate the limitation. Understanding the impacts of agriculture management on microbial community and its association with nutrient availability would provide strong supports for alleviating continuous cropping limitation. However, the mechanisms of fumigants in enhancing plant growth and alleviating continuous cropping barriers was not clear. In this study, fumigation treatments including chloropicrin (CP), dazomet (DZ), and untreated control (CK) were carried out at field scale, and rhizosphere bacterial community and plant phytochrome were analyzed. The results showed that fumigation had strong effects on rhizosphere bacterial community and soil properties. Fumigation treatment caused significantly reduction in rhizosphere bacterial diversity. The nitrifiers (Nitrospira and Nitrospirillum) and functional gene (ammonia oxidizing bacterial AOB amoA) were significantly inhibited by fumigation treatment, which caused significant reduction in nitrification potential (PNF). The inhibition of nitrifiers, AOB amoA gene and PNF led to significant reduction of soil NO3−-N, but increase of NH4+-N. Subsequently, plant photosynthesis was enhanced as a result of increasing leaf chlorophyll a content caused by fumigation treatment. Therefore, fumigation treatment would promote crop growth through increasing the photosynthetic pigment. The study indicated the key mechanisms fumigation promoting plant growth and alleviating cropping limitation were closely related to soil nitrifiers and nitrogen nutrients.

Plant rhizosphere defense system respond differently to emerging polyfluoroalkyl substances F-53B and PFOS stress.

Chlorinated polyfluoroalkyl ether sulfonate (F-53B) and perfluorooctanesulfonate (PFOS) are used and emitted as fog inhibitors in the chromium plating industry, and they are widely detected worldwide. To study the effects of F-53B and PFOS on the rhizosphere defense system, they were added at two levels (0.1 and 50mgL-1) to the soil where different plants (Lythrum salicaria and Phragmites communis) were grown. In bulk soils, high concentrations of F-53B/PFOS resulted in significant increases in soil pH, NH4+-N, and NO3--N (the effect of PFOS on NO3--N was not significant). Moreover, the extent of the effects of PFOS and F-53B on the physicochemical properties of bulk soils were different (e.g., PFOS caused an increase of NH4+-N by 8.94%-45.97% compared to 1.63%-25.20% for F-53B). Root exudates and PFASs together influenced the physicochemical properties of rhizosphere soils (e.g., TOC increased significantly in contaminated rhizosphere soils but did not change in non-bulk soils). Under the influence of F-53B/PFOS, the root exudates regulated by plants were changed and weakened the effect of F-53B/PFOS on microbial community of rhizosphere soil. The rhizosphere defense systems of different plants have both similarities and differences in response to different substances and concentrations.

Artificial aeration of an overloaded constructed wetland improves hypoxia but does not ameliorate high nitrogen loads

High organic loadings to constructed wetlands can result in water quality issues such as low dissolved oxygen and high ammonium concentrations, with artificial aeration a potential mitigation option. This study compared baseline (no aeration – NA), continuous aeration (CA), and intermittent aeration (IA) conditions to improve water quality in a tertiary treatment free water surface constructed wetland (FWS CW) with night time hypoxia/anoxia, and high nutrient concentrations. The response variables included dissolved oxygen (DO), total nitrogen (TN), ammonium nitrogen (NH4+-N), nitrate nitrogen (NO3−-N), total phosphorus (TP), phosphate (PO43–-P), and dissolved organic carbon (DOC). In situ aeration and monitoring was performed from April to June 2021 in a large, field-scale FWS CW, the Laratinga wetlands Mount Barker, South Australia.The results demonstrated that DO increased by an average 2.11 mg L−1 from NA to CA during the night and 1.26 mg L−1 and 1.84 mg L−1 from NA to IA during the night and day respectively when averaging over the basins. The C/N ratio was very low and there was no significant influence of DO on DOC concentrations. There was no significant difference in TN concentrations with the application of aeration aside from a decrease in the channel at night from NA to IA, and an increase in NH4+-N resulted under IA compared with NA in Basin 1 and 2 during the day. This implies that the N loadings exceeded the wetland's ability to complete nutrient conversions at a rate that aligns with input rate. The concentrations of NO3−-N increased at night under CA and IA treatments suggesting that some nitrification was promoted, or there was inhibition of dissimilatory nitrate reduction to ammonium. The concentrations of TP and PO43–-P significantly increased with the aeration compared with no aeration, however there was no difference between the aeration treatments. This suggested that increased sediment resuspension during aeration increased P in the water. There was no change in DOC with the application of aeration. Overall, the DO increased with aeration application and may be able to better support the wetland ecology; however, the Laratinga wetland is overloaded and the capacity of the wetland to effectively transform and remove nutrients is inhibited, even with the application of artificial aeration.

Effects of Eugenol on Water Quality and the Metabolism and Antioxidant Capacity of Juvenile Greater Amberjack (Seriola dumerili) under Simulated Transport Conditions.

Simple SummaryThe transportation of live fish is a very important part of the aquaculture system. The health status of fish can be affected in the closed-container transportation system. It has become very common to relieve the stress of fish in transport by adding anesthetics. With the food safety of fish having gained widespread attention, the addition of plant extracts as an alternative to anesthetics has become an important research topic. The objective of this study was to evaluate the effects of eugenol addition during simulated transport on water quality, and the metabolism and antioxidant capacity of liver and gills in the greater amberjack (Seriola dumerili). It was found that the addition of eugenol under simulated transport conditions had positive effects on water quality, and on liver and gill metabolism and antioxidant capacity in the greater amberjack. This study contributes to the healthy culture of the greater amberjack.This study investigated the effects of added eugenol on water quality and the metabolism and antioxidant capacity of the liver and gills of the greater amberjack (Seriola dumerili) during simulated transport. The juvenile fish (10.34 ± 1.33 g) were transported in sealed plastic bags containing different eugenol concentrations at a density of 24.79 kg/m3 for 8 h. The different eugenol concentrations were divided into five groups: 0 μL/mL (control group), 0.0125 μL/mL, 0.025 μL/mL, 0.0375 μL/mL, and 0.05 μL/mL, with three replicates of each. The results showed that 0.05 μL/mL of eugenol could significantly increase dissolved oxygen, but 0.025 μL/mL–0.0375 μL/mL resulted in a significant decrease in dissolved oxygen and significant increases in NH4+-N and NO2−-N. It was found that 0.05 μL/mL of eugenol caused significant up-regulation of the relative expression of CPT-1 in the liver, significant down-regulation of the relative expression of FAS and PK in the liver and gills, a significant increase in glycogen concentration, and a significant decrease in glucose concentration. This suggests that 0.05 μL/mL of eugenol could reduce the metabolic capacity of fish. In addition, 0.05 μL/mL of eugenol caused significant up-regulation of the relative expression of CAT and a significant decrease of MDA concentration in the liver. Meanwhile, the gills showed significant up-regulation of CAT relative expression, significant down-regulation of Keap1 relative expression, and a significant increase in GSH activity, resulting in a significant increase in MDA concentration when the concentration of eugenol reached or exceeded 0.025 μL/mL. This suggests that 0.05 μL/mL eugenol could improve the antioxidant capacity of fish and lipid peroxidation levels in the gills. In conclusion, the addition of 0.05 μL/mL eugenol could improve water quality, and the metabolic and antioxidant capacities of liver and gills, but it could also increase lipid peroxidation levels in the gills under transport conditions.

Effect of Filter Medium on Water Quality during Passive Biofilter Activation in a Recirculating Aquaculture System for Oncorhynchus mykiss

High-performance biofilters for water purification in recirculating aquaculture systems (RAS) ensure the safety of cultures of highly nutritious fish. As the most critical step in the functioning of biofilters is their activation, the objective of this study was to evaluate the suitability of commercial artificial media, namely RK Plast (BR-1), Mutag-BioChip30 (BR-2), and LevaPor (BR-3), for the passive activation of biofilters used in rainbow trout farming. Changes in NH4+-N, NO2−-N, NO3− -N, phosphorus, and carbon concentrations were analyzed. In the first period, an increase in NH4+-N concentration was recorded, before an increase in NO2−-N concentration (maximum concentrations ranged 0.728–1.290 and 0.982–5.198 mg N dm−3, respectively), followed by a reduction and stabilization to a level safe for the fish (both below 0.100 mg N dm−3). Concurrently, a steady increase in NO3−-N concentration was noted, with a maximum concentration between 6.521 and 7.326 mg N dm−3. Total phosphorus and total carbon ranged from 0.423 to 0.548 mg P dm−3, and from 43.8 to 45.2 mg C dm−3. The study confirmed the feasibility of using the tested artificial biofilter media for rainbow trout farming in RAS with passive biofilter activation. Biofilter activation efficiency was highest for the media with the highest specific surface area (BR-2 and BR-3). The removal of ammonium nitrogen and nitrite nitrogen was above 90%. Nitrogen biotransformation was not limited by phosphorus or carbon concentrations.

Differential Impact of Exposure to PM2.5 Composition and Contributing Sectors on Anemia Prevalence Amongst Children Under age five in India

Anemia, a condition of low red blood cell count and diminished hemoglobin levels, is highly prevalent in India. India has one of the highest anemia prevalence approx. 60% among children under age five (U5) in the world. Ambient PM2.5 exposure has been identified as a potential risk factor for anemia via systemic inflammation. Moreover, whether the impact varies with PM2.5 composition and sources contributing to such components is not known. Here, we examine the differential impact of exposure to ambient PM2.5 components on anemia prevalence among children U5 in India using exposure data from the CMAQ model and satellite-derived PM2.5, health data from the NFHS-IV. Here we focus on the exposure to PM2.5 components such as Black Carbon, Organic Carbon, nitrate (NO3), ammonium (NH4), sulfate, soil, and others, during the early life period. We use multilevel models adjusted for the risk factors - smoking, cooking fuel, BMI, wealth, and residence to assess the impact of PM2.5 components on anemia prevalence among children. At the ecological level, for every IQR increase in ambient PM2.5 exposure, the odds ratio for average anemia prevalence is 1.19 (95% UI: 1.17,1.22). For each IQR of NO3, anemia prevalence increased with an odds ratio of 1.26 (95% UI: 1.24,1.29). For the corresponding increase in NH4, others, BC, OC, SO4, and soil, anemia prevalence increased by odds ratio 1.19 (95% UI: 1.17,1.21), 1.16 (95% UI: 1.14, 1.18), 1.15 (95% UI: 1.13, 1.17), 1.11 (95% UI: 1.09, 1.13), 1.12 (95% UI: 1.11,1.13), and 1.10 (95% UI: 1.08,1.11), respectively. Sectorally, the domestic sector has the highest impact, followed by the unorganized sectors, road dust, agriculture waste, industry, etc. Our results will support the policymakers to target specific sectors that are contributing to exposure to PM2.5 and its components and, in turn, causing lethal health impacts. Keywords- Anemia, PM2.5, LMICs