Organic Sources Research Articles

Impact of organic and inorganic fertilizers on the growth and yield of Beetroot (Beta vulgaris L.) in the hilly region of Nepal

The use of both organic and inorganic fertilizers plays a crucial role in farming practices in Nepal, depending on their availability. Applying fertilizers like compost, vermicompost, goat manure, and NPK has shown significant effects on various aspects of plant growth and yield. This study was conducted in Diktel, Khotang district of Nepal, from March 14th to June 7th, 2023, aiming to evaluate how different organic and inorganic sources affect the growth and yield of beetroot (Beta vulgaris L.). The experiment followed a one-factor randomized complete block design (RCBD) with four replications, involving five treatments: T1: 100% Compost manure, T2: 100% Vermicompost, T3: 100% Goat manure, T4: 100% NPK, and T5: Control. The results clearly showed that both vegetative and reproductive traits were significantly varies among several treatments utilized in the experiments at 0.1% level of significance. Compost application consistently showed better results across most growth and yield parameters assessed. Growth parameters included plant height, leaf count per plant, leaf length, and leaf width, while yield parameters included beetroot diameter, beetroot length, root yield, and leaf yield. Organic compost manure particularly stood out, displaying significantly larger beetroot diameter (4.85 cm) and greater beetroot length (9.3 cm). Additionally, compost manure led to notably increased root yield (13.95 t/ha) compared to the control treatment, which recorded a lower root yield (6.28 t/ha). Overall, all treatments outperformed the control in terms of growth and yield parameters. These findings suggest that organic compost manure is the most favorable choice for achieving high-quality beetroot production in the hilly regions of Nepal.

Significance and Applications of the Thermo-Acidophilic Microalga Galdieria sulphuraria (Cyanidiophytina, Rhodophyta).

Galdieria sulphuraria is a thermo-acidophilic microalga belonging to the Cyanidiophyceae (Rhodophyta) class. It thrives in extreme environments, such as geothermal sulphuric springs, with low pH, high temperatures, and high salinity. This microalga utilises various growth modes, including autotrophic, heterotrophic, and mixotrophic, enabling it to exploit diverse organic carbon sources. Remarkably, G. sulphuraria survives and produces a range of bioactive compounds in these harsh conditions. Moreover, it plays a significant role in environmental remediation by removing nutrients, pathogens, and heavy metals from various wastewater sources. It can also recover rare earth elements from mining wastewater and electronic waste. This review article explores the diverse applications and significant contributions of G. sulphuraria.

Downed woody debris varies with climate and harvesting treatment in Douglas-fir forests of British Columbia, Canada

Downed woody debris is important for biodiversity, forest regeneration, and carbon, nutrient, and water cycling, and past studies have examined how the coarse fraction is affected by climate or harvesting. In a field study in Douglas-fir dominated forests, we expand existing knowledge by investigating the interacting effects of climate and harvesting on downed woody debris of all sizes. Across a 900-km long latitudinal gradient in British Columbia, we found that coarse woody debris (CWD, >7.5 cm diameter) in humid climates contained 700% greater carbon stocks, had 500% greater volume, and was more diverse than in arid climates. Pre- and post-harvest, small and fine woody debris comprised a higher proportion of total woody debris carbon stocks in arid than moist climates, especially after clearcutting and seed tree treatments. Harvesting generally decreased total CWD volume, but it was not depleted on any site. Harvesting substantially reduced the volume of large, highly decomposed CWD except at the two most arid sites, and losses of large CWD increased with increasing tree removal. These losses were accompanied by a pulse of fresh, small diameter CWD and SWD which are short-term organic nutrient sources but have less habitat value than larger pieces and contribute to fuel loads. Because CWD was less abundant in arid than humid mature forests, care must be taken on arid sites to avoid its depletion during harvesting, especially clearcutting, where future woody debris inputs will not occur for decades.

Effects of Combined Organic Selenium and Zinc Supplementation on In Vitro Ruminal Enzyme Activities and Relative Populations of Several Bacterial Species

Selenium (Se) and zinc (Zn) are essential animal microminerals. Combining Se and Zn (Se-Zn) as a feed additive in its influence on rumen fermentation patterns is still very limited, so further investigation is needed. The present study explored the supplementation impact of combined Se-Zn from organic sources on rumen enzyme activity and relative abundance of several bacterial species through an in vitro method. Five treatments, each with six replicates were used in the study. The first group treated without Se and Zn supplementation (T0, control), the second group treated with 0.3 ppm Se + 60 ppm Zn (T1), the third group treated with 0.45 ppm Se + 60 ppm Zn (T2), the fourth group treated with 0.3 ppm Se + 90 ppm Zn (T3), and the fifth group treated with 0.45 ppm Se + 90 ppm Zn (T4). The parameters observed included rumen microbial enzyme activities (carboxyl methyl cellulase, amylase, protease) and the relative abundance of rumen microbes (Ruminococcus sp., Ruminococcus flavefaciens, Ruminococcus albus, Streptococcus sp., Prevotella ruminicola, and Eubacterium ruminantium). Results indicated that carboxyl methyl cellulase (CMC-ase) and amylase activities raised in T2, T3, and T4 in comparison to T1 and T0 treatments. Protease activity and protein enzyme content increased in T2 compared to all treatments. The relative abundance of Ruminococcus sp. and Ruminococcus albus was higher in T2 and T3 compared to T0 treatment. Furthermore, an elevated Ruminococcus flavefaciens was indicated in T2 compared to other treatments. The T2, T3, and T4 led to higher abundances of Eubacterium ruminantium, Prevotella ruminicola, and Ruminococcus albus compared to T0 and T1. It is concluded that organic Se and Zn enhanced the relative abundance of several bacterial species and the activity of enzymes in the rumen; optimal results are recommended when combining 0.45 ppm Se + 60 ppm Zn.

Application of different organic amendments influences the different forms of sulphur in the soil of pea – onion – cauliflower cropping system

A study was conducted in sandy clay loam soils in a subtropical zone of Bihar to evaluate the effect of frequent application of organic amendments on sulphur fractions. Different organic amendments, including farmyard manure (FYM), vermicompost, azotobacter, phosphate solubilizing bacteria (PSB), panchagawya, and neem cake, were applied through nine treatments that resulted in a significant increase of water-soluble S, available S, heat-soluble S, adsorbed S, and organic S in organic treatment compared to the recommended dose of fertilizer (RDF) and control treatment. The maximum increment was observed in the treatment where the recommended dose of nitrogen was replaced by 75% recommended dose of nitrogen substituted farmyard manure + 25% recommended dose of nitrogen (vermicompost) along with azotobacter + PSB + one foliar spray of panchagawya. The total S content varied widely from 382 to 736 mg kg-1. Increment in all the forms of sulphur is observed as a result of the application of different organic nutrient sources. All the forms of sulphur share a mutual positive and significant correlation with each other. Regression analysis suggested that the availability of sulphur was dominated by organic sulphur, which alone can explain 97.8% of the variation in availability of available sulphur in soil.

Effect of Organic and Inorganic Sources of Nitrogen on Growth Parameter and Yield Attribute of Wheat in Inceptisolof Eastern Uttar Pradesh, India

The insufficient availability and escalating expenses of fertilizers present significant constraints to crop production, exacerbating the growing disparity between nutrient demand and supply. The overreliance on agrochemicals like synthetic fertilizers, pesticides, herbicides, and fungicides not only endangers human health but also degrades soil quality and environmental integrity. This study examined the impact of applying recommended doses of fertilisers (RDF) in conjunction with organic amendments in a pot experiment carried out throughout the 2020–2021 wheat growing season. Significant improvements were found for the following wheat plant attributes: straw and grain yields; height; greenness index; spike count; spike length; and weight of 1000 seeds. The treatment utilizing 50% RDF and 50% poultry manure (T5) demonstrated the most pronounced improvements across these parameters. These findings highlight integrated nutrient management's crucial importance as a modern agricultural requirement.

Effect of Organic Manures on Productivity in a Groundnut-Wheat Sequence under Organic Farming

An experiment was conducted during two consecutivekharif and rabi season from the year 2016-17 to 2018-19 for three years on to evaluate different organic sources performance on groundnut and wheat sequence under organic farming at Agronomy Instructional Farm, Chimanbhai Patel College of Agriculture, Sardarkrushinagar Dantiwada Agricultural University, Sardarkrushinagar. The soil of experiment was loamy sand. Experiment was carried out in Large plot technique design and with eight replication for four treatments. From three years experiment result revealed that in kharif season, application of 100% nitrogen through castor cake sequring higher pod yield of groundnut and application of 75% nitrogen through castor cake for succeding wheat in rabi season for getting higher seed yield. Application of castor cake in both season sequred higher groundnut equivalent yield. Maximum gross (Rs 150300/ha) and net neturn (Rs 67922/ha) with BCR of 1.82 was obtained under Treatment T3 (100% RDN through castor cake in groundnut and 75% RDN through castor cake in succeeding wheat) under organic farming under North Gujarat Agro climatic conditions.

Effect of Nutrient Management on Physico-chemical Properties of Soil in Indian Mustard

A field experiment was conducted at the IFS Unit Instructional Farm of Banda University of Agriculture & Technology, Banda (UP) during the winter (rabi) seasons of 2022-23 and 2023-24. The study aimed to examine the impact of nutrient management on the soil properties of Indian mustard (Brassica juncea L.) grown in clay loam soil. Mustard, an essential oilseed crop in India, encounters issues like low productivity and diminished soil fertility caused by excessive use of chemical fertilizers. The paper highlights the importance of integrating chemical and organic sources, such as vermicompost. Vermicompost enriched with biofertilizers, especially Azotobacter, PSB, PMB, NPK Consortia, and ZSB demonstrates significant potential in improving the soil conditions for mustard crops. The experiment utilized a split plot design (SPD) with four main factors in the main plot and four levels in the sub-plot, resulting in sixteen treatment combinations, each applied three times. The soil at the experimental site was characterized by a clay loam texture and low levels of organic carbon, available nitrogen, phosphorus, zinc and sulfur, with moderate levels of available potash. The main plot treatments consisted of different fertility levels: 50% RNPKS, 75% RNPKS, 100% RNPKS and 125% RNPKS. Each main plot was further divided into four sub-plots, each with a combination of micronutrients and enriched vermicompost. The results indicated that the treatment of either 125% or 100% RNPKS and 2.5 kg Zn + 0.5 kg B + 500 kg enriched vermicompost ha-1 was superior in improving the soil properties for Indian mustard.

Aerobic and anaerobic mineralisation of sediment organic matter in the tidal River Elbe

PurposeThe share of microbially degradable sediment organic matter (SOM) and the degradation rate depend, among others, on the intrinsic properties of SOM as well as on the type and concentration of terminal electron acceptors (TEA). Next to its role as TEA, molecular oxygen enhances SOM decay by oxygenase-mediated breakdown of complex organic molecules. This research investigated long-term SOM decay (> 250 days) under aerobic and anaerobic conditions to (1) provide a basis for sediment carbon flux estimates from the River Elbe estuary and (2) assess the potential for carbon burial in relation to redox conditions and dredging interventions.MethodsLong-term aerobic and anaerobic SOM decay in fluid mud, pre-consolidated and consolidated sediment layers was investigated over three years along a transect of ca. 20 km through the Port of Hamburg, starting at the first hydrodynamically determined hotspot of sedimentation after the weir in Geesthacht. Absolute differences between aerobic and anaerobic cumulative carbon mineralization were calculated, as well as their ratio. Findings were correlated to a suite of solids and pore water properties.ResultsSOM decay followed first order multi-phase exponential decay kinetics. The ratio between C release under aerobic and anaerobic conditions ranged around 4 in the short-term, converging to a value of 2 in the long term. Strong gradients in absolute C release along the upstream–downstream transect did not reflect in a corresponding gradient of the aerobic-anaerobic ratio. C release was most strongly correlated to the water-soluble organic matter, in particular humic acids. Contact of anaerobically stabilized sediment with the oxygenated water phase induced significant release of carbon.ConclusionSOM degradability in the study area exhibited strong spatial gradients in relation to the organic matter source gradient but was mainly limited by the high extent of organic matter stabilization. Under these conditions, molecular oxygen as TEA provides little thermodynamic advantage. Carbon-sensitive sediment management, considering SOM reactivity patterns in stratified depositional areas, is a powerful strategy to reduce environmental impacts of dredging measures.

Uncovering the characteristics of plastic-associated biofilm from the inland river system of Mongolia

The occurrence and characteristics of plastic debris in aquatic and terrestrial environments have been extensively studied. However, limited information exists on the properties and dynamic behavior of plastic-associated biofilms in the environment. In this study, we collected plastic samples from an inland river system in Mongolia and extracted biofilms to uncover their characteristics using spectroscopic, isotopic, and thermogravimetric techniques. Mixtures of organic and mineral particles were detected in the extracted biofilms, revealing plastic as a carrier for exogenous substances, including contaminants, in the river ecosystem. Thermogravimetric analysis (TGA) indicated the predominant contribution of minerals primarily comprising aluminosilicate and calcite, representing approximately 80 wt% of the biofilms. Differential thermal analysis (DTA) coupled with Fourier transform infrared (FTIR) spectrometry operated at 25°C–600 °C enabled the detection of gaseous decomposition products, such as CO2, H2O, CO, and functional groups (O–H, C–H, C–O, CO, CC, and C–C), released from biopolymers in the extracted biofilms. Dehydration, dehydroxylation, and decarboxylation reactions explain the thermal properties of biofilms. The stable carbon (δ13C) and nitrogen (δ15N) isotope ratios of the biofilms demonstrated variable signatures ranging from −24.1‰ to −27.0‰ and 3.1‰–12.3‰, respectively. A significant difference in the δ13C value (p < 0.05) among the upstream, middle, and downstream research sites could be characterized by available organic carbon sources in the river environment, depending on the research sites. This study provides insights into the characteristics and environmental behavior of biofilms which are useful to elucidate the impact of plastic-associated biofilms on organic matter and material cycling in aquatic ecosystems.

Insights into organic matter source and depositional environments of shales from the Ponta Grossa Formation in Parana basin, Brazil

Marine transgression events and plant species' evolution to terrestrial environments increased the amount of organic matter in sediments during the Devonian Period. Subsequently, a bituminous material known as shale was formed, containing organic compounds that enable the reconstruction of environmental conditions from previous eras. These rock formation events are recorded worldwide, however, in the Ponta Grossa Formation, southern Brazil, a deeper understanding of samples from the Devonian Period is necessary. The goal of this study was to understand the regional environmental conditions, the origin of the organic matter, and the degree of maturation of the bituminous material. Shale samples were collected from an outcrop on the eastern border of the Paraná Basin and processed in the laboratory to obtain the saturated hydrocarbons fraction posteriorly analyzed. The results indicate a poorly oxygenated environment, with various salinity levels, mixed organic sources, and a high thermal maturity of the samples. The analysis of compound hydrocarbons elucidates the environmental conditions during the Devonian Period in the Ponta Grossa Formation, providing inferences applicable to the stratigraphic interval represented by this record and within the domain of the sampled area.

Efficient activation of persulfate for tetracycline hydrochloride degradation by biochar prepared from corn stover doped with organic phosphorus sources

Proposed to prepare phosphorus-doped biochar catalyst materials by impregnation pyrolysis method using corn stover and different phosphorus source precursors as raw materials, and the batch-wise research revealed that the phosphorus source precursor, the doping ratio, and the pyrolysis temperature had a significant influence on the biochar properties. The biochar material Pb-C-4–600 prepared with (C4H9)3PO4 as phosphorus source precursor, 1:4 doping ratio, and pyrolysis temperature of 600 ℃ had an ID/IG = 0.914, pore size of 4.91 nm, and specific surface area of 173.9845 m²/g, which was 93.4 times higher than that of the pure biochar. The removal rate of TCH reached 99.77 % in 30 min under the reaction conditions of PMS concentration of 2 g/L, Pb-C-4–600 dosage of 1 g/L, and pH 3. Comparing the efficacy of Pb-C-4–600 and different catalysts for the degradation of TCH by activated PMS under the same reaction conditions, the degradation reaction rate of Pb-C-4–600 was 0.17663 min−1, which was 1.48 times higher than that of N-bio, 1.67 times higher than that of S-bio, and 2.64 times higher than that of B-bio, which further demonstrating the advantages of Pb-C-4–600 in similar composites. The oxidative degradation performance of other typical organic pollutants (BPA, phenol, AO7) was also good. The prominent reactive oxidizing radical in the system of Pb-C-4–600/PMS was SO4·−, and the system could adapt to a wide pH range.

Optimizing agricultural sustainability: enriched organic formulations for growth, yield, and soil quality in a multi-crop system.

Utilizing agricultural and industrial wastes, potent reservoirs of nutrients, for nourishing the soil and crops through composting embodies a sustainable approach to waste management and organic agriculture. To investigate this, a 2-year field experiment was conducted at ICAR-IARI, New Delhi, focusing on a pigeon pea-vegetable mustard-okra cropping system. Seven nutrient sources were tested, including a control (T1), 100% recommended dose of nitrogen (RDN) through farmyard manure (T2), 100% RDN through improved rice residue compost (T3), 100% RDN through a paddy husk ash (PHA)-based formulation (T4), 75% RDN through PHA-based formulation (T5), 100% RDN through a potato peel compost (PPC)-based formulation (T6), and 75% RDN through PPC-based formulation (T7). Employing a randomized block design with three replications, the results revealed that treatment T4 exhibited the significantly highest seed (1.89 ± 0.09 and 1.97 ± 0.12 t ha-1) and stover (7.83 ± 0.41 and 8.03 ± 0.58 t ha-1) yield of pigeon pea, leaf yield (81.57 ± 4.69 and 82.97 ± 4.17 t ha-1) of vegetable mustard, and fruit (13.54 ± 0.82 and 13.78 ± 0.81 t ha-1) and stover (21.64 ± 1.31 and 22.03 ± 1.30 t ha-1) yield of okra during both study years compared to the control (T1). Treatment T4 was on par with T2 and T6 for seed and stover yield in pigeon pea, as well as okra, and leaf yield in vegetable mustard over both years. Moreover, T4 demonstrated notable increase of 124.1% and 158.2% in NH4-N and NO3-N levels in the soil, respectively, over the control. The enhanced status of available nitrogen (N) and phosphorus (P) in the soil, coupled with increased soil organic carbon (0.41%), total bacteria population (21.1%), fungi (37.2%), actinomycetes (44.6%), and microbial biomass carbon (28.5%), further emphasized the positive impact of T4 compared to the control. Treatments T2 and T6 exhibited comparable outcomes to T4 concerning changes in available N, P, soil organic carbon, total bacteria population, fungi, actinomycetes, and microbial biomass carbon. In conclusion, treatments T4 and T6 emerge as viable sources of organic fertilizer, particularly in regions confronting farmyard manure shortages. These formulations offer substantial advantages, including enhanced yield, soil quality improvement, and efficient fertilizer utilization, thus contributing significantly to sustainable agricultural practices.

Enhanced nitrate removal through autotrophic denitrification using microbial fuel cells via bidirectional extracellular electron transfer

The novel biological denitrification process with electrochemical system using the bio-cathode of microbial fuel cells (MFC) presents a promising approach to reduce electron donor consumption during wastewater treatment. This method of autotrophic denitrification can utilize inorganic compounds (such as H2, S2-, S2O32- etc.) or electrodes (at a constant potential) to provide electrons for the denitrification process. This study focuses on an isolated autotrophic denitrifier strain Lyy (belonging to Stutzerimonas) and its application in bio-cathode denitrification. It was found that the extracellular electron transfer (EET) pathway between strain Lyy and electrode is facilitated via the electron shuttle phenazine-1-carboxylic acid (PCA). Especially, at a potential of −0.6 V (vs. SCE), strain Lyy can mediate inward EET from electrodes or inorganic compound into cells, enhancing denitrification with a NO3--N removal efficiency of 98.68 ± 0.68 % within 48 h. On the other hand, effective denitrification was achieved by the bio-cathode MFC without organic carbon sources. Meanwhile, the MFC exhibited a maximum output voltage of 172 ± 6 mV and a maximum power density of 77.46 ± 6.49 mW m−2 at a load resistance of 1 kΩ, with a NO3--N removal efficiency higher than 95 % and with no detecteable NO2--N, which implied that bio-cathode denitrification contributes to the electricity generation. This study showed bidirectional EET phenomena and expands the potential applications for treating low-carbon, high-nitrogen wastewater using strain Lyy.

Optimizing phosphorus requirement of seed potato through organic and inorganic sources in north-west India

Phosphorus optimization is essential to maximize seed-size potato productivity and reduce the occurrence of over-sized and under-sized tubers. A field experiment was conducted for two years at the two locations in Punjab, India to investigate the effects of organic and inorganic phosphorus management on seed potato productivity. The experiment was conducted in a split-plot design with three organic (farmyard manure, biofertilizer, and control) treatments in main plots and five fertilizer phosphorus (0, 46.9, 62.5, 93.8, and 125 kg/ha P2O5) treatments in subplots. The application of farmyard manure (50 t/ha) resulted in a significant increase in growth and yield attributes, tuber yield, seed size (3.5–4.5 cm) tuber number, and economic returns. The percentage increase in seed size tuber number and tuber yield with farmyard manure over the control was 36.6% and 29.3%, respectively. Among the fertilizer phosphorus levels, the highest growth attributes, tuber yield, seed size tuber number and economic returns were obtained with a 125 kg/ha. The application of 125 kg/ha fertilizer phosphorus resulted in a 36.3% and 23.0% (mean) increase in seed size tuber number and tuber yield compared to the unfertilized phosphorus (0 kg/ha). No significant organic sources x fertilizer phosphorus levels interaction effects were found on any of the traits evaluated at both locations. The result of this study indicates that P management can play an important role in increasing seed size and productivity.

Impact of integrated nutrient management and foliar zinc supplementation on rice (Oryza sativa L.) nutrient uptake and yield in the Cauvery Delta Zone

In 2023, rice production reached 523.9 million tons, making it the fourth most produced crop globally. Accounting for 14% of global fertilizer use, the demand for rice continues to increase. However, the unbalanced application of NPK fertilizers poses significant environmental risks. An integrated nutrient management approach, combining organic and inorganic sources, offers a cost-effective solution to meet crop nutritional needs while enhancing soil health. Therefore, a field experiment was conducted in Experimental Farm of Annamalai University during kuruvai (June-September) 2023 to evaluate the effect of different levels of inorganic fertilizers with different sources of organic manures along with foliar zinc sulphate on the yield and yield components in lowland rice. The experiment was laid out in randomized block design with nine treatments. These treatments included different sources of organic manures viz., farm yard manure, vermicompost, press mud and poultry manure and foliar application of zinc sulphate. The results revealed that combining 75% nitrogen through urea and 25% nitrogen from vermicompost and 100 % P and K along with foliar application of zinc sulphate (0.5%) at 25 and 50 days after transplanting (DAT) significantly improved all nutrient uptake of nitrogen, phosphorous and potassium and also yield parameters viz., number of productive tillers m-2, number of filled grains/panicle, grain yield, straw yield and harvest index of rice.

Iron-based mixotrophic denitrification for enhancing nitrate removal from municipal secondary effluent: Performance, microbial community dynamics, and economic feasibility

High nitrate content limits the recycling of the secondary effluent of wastewater treatment plants. In the research, one biomass-iron mixture (BIM) filter material based on mixotrophic denitrification mode (heterotrophic and iron-driven autotrophic denitrification) was developed and used to construct a novel denitrification biological filter (BIM-DNBF) for the nitrogen removal of secondary effluent. BIM-DNBF had a short start-up time (approximately 9 days), and high total nitrogen removal (81 %-89 %) without external addition of organic carbon sources during the whole operation. The coexistence of dominant heterotrophic-denitrification-like Pseudomonas and Erysipelothrix as well as iron-driven autotrophic-denitrification-like Citrobacter, Acidovorax, etc. were found in the BIM-DNBF. Moreover, biomass was recognized as one key player in promoting the reduction of Fe3+ to Fe2+, thereby facilitating the occurrence of iron-driven autotrophic denitrification. In addition, BIM-DNBF was assessed to be affordable. These findings provide evidence that BIM-DNBF can be an efficient technology for nitrogen removal of secondary effluent.

Effect of Different Organic Nutrient Sources on the Growth and Yield of Summer Sesamum (Sesamum indicum L.)

Effect of Different Organic Nutrient Sources on the Growth and Yield of Summer Sesamum (Sesamum indicum L.)

Challenges in the determination of reactive oxygen species evolving during membrane water electrolysis for in situ ozone production

The treatment of ultrapure water with electrochemically produced O3 is a common means for disinfection yet leads to the formation of a variety of reactive oxygen species (ROS). The present study draws a comprehensive comparison between three commonly used photometric and fluorometric assays for ROS analysis and quantifies the individual signal responses for dissolved O3, ·OH and H2O2, respectively, to account for cross-sensitivities. By calibrating all combinations of assays and analytes, we developed a quantification procedure to reliably determine the actual ROS composition in ultrapure water environments for different operation conditions of a membrane water electrolyzer with PbO2 anodes down to concentrations of 0.97 μg L−1. While the ·OH formation rate can be described linearly over the observed current density range, substantial O3 evolution is only found for current densities of 0.75 A cm−2 and above (up to 3.7 μmol h−1 for J = 1.25 A cm−2). The formation of H2O2 is only observed when an organic carbon source is introduced into the solution. We further quantify the interference of H2O2 with the reading of the oxidation-reduction potential as a common water parameter and elaborate on its validity to monitor the peroxone process when both H2O2 and O3 are present simultaneously.

Effects of VOC emission reduction on atmospheric photochemistry and ozone concentrations during high-ozone episodes

We studied atmospheric volatile organic compounds (VOCs) characteristics and sources during fifteen high ozone (O3) episodes (daily 1-h maximum >100 ppbv and maximum 8-h average > 80 ppbv) in Nanjing, China, and used a photochemical box model to study the O3 formation sensitivity of VOCs, O3 photochemistry, radical budget, and reactivity for different emission reduction scenarios together with the base case ones. Overall, emission reduction from biogenic sources, followed by combustion sources, multiple sources, and solvent usage, had the major impacts on the O3 concentrations. According to photochemical box model simulations, isoprene was the most sensitive or influential VOC in the formation of O3, followed by ethylene, o-xylene, and cis-2-pentene. A 20.6 ± 11.7% concentration reduction of the sixteen most sensitive VOCs (SV16) for the production of O3 could bring the O3 concentration below the national standard level (daily 1-h maximum <100 ppbv). Besides, a 30% emission reduction from all the anthropogenic sources was more than enough to bring the O3 concentration below the national standard level. The total emission reduction of alkenes was always enough to bring the O3 concentration below the national standard level, which was not the case for aromatics under severe pollution conditions. The simulated OH reactivity analysis illustrates the importance of alkenes and aromatics, which account for about half of the total OH reactivity. The highest OH reactivity decreased due to the emission reduction for biogenic sources, followed by combustion and multiple sources. Alkenes played a major role in the OH, HO2, and RO2 radical's formation in the study area. The biggest drop in OH, HO2, and RO2 radical concentrations was noticed for biogenic emission reduction, followed by combustion and multiple sources. Due to the emission reduction from VOC sources, the highest O3 formation rates decreased for biogenic sources, followed by combustion and multiple sources. The acquired information is valuable to the scientific community and policymakers for formulating and implementing O3 pollution control strategies.