Addition Of KNO3 Research Articles

Relative contributions of bacteria and fungi to nitrous oxide emissions following nitrate application in soils representing different land uses

Bacteria and fungi have been shown to produce nitrous oxide (N2O) during denitrification, but their contribution after nitrate (NO3−) application to soil is not clearly established. In a microcosm experiment, the relative contribution of bacteria and fungi to N2O and carbon dioxide (CO2) production by four contrasting soils representing different land uses after KNO3 addition was studied. The soils were daily wetted to 80% water-filled pore space (WFPS) and kept under greenhouse conditions for 10 days. The fungicide cycloheximide and the bactericide streptomycin were used to determine the possible microbial origin of the N2O and CO2 emissions. Non-target effects of the antibiotics on the emission of N2O and CO2 were evaluated using the inhibitor additivity ratio (IAR). The abundance of the bacterial and fungal communities was estimated by quantitative PCR (qPCR) of the bacterial 16S rRNA gene and the fungal internal transcribed spacer (ITS) region, respectively. The gene copy number of bacterial denitrifiers was calculated after quantification of the nirK, nirS, norB, nosZI and nosZII genes. After 10 d, regardless of the soil type, the cumulative N2O emission from the soils treated with cycloheximide or streptomycin were similar. In all the four soils, N2O fluxes were greater (on average 1.8 ± 0.3 times) in soils amended with the fungicide than with the bactericide during incubation for the first 48–96 h. Greater N2O emissions (on average 1.7 ± 0.2 times) were detected in soils where bacteria were inhibited in comparison to those treated with the fungicide from 96 to 240 h. On average, 68.5% of the total CO2 emitted during the 10-d incubation period was produced in soils treated with the fungicide and 31.5% in those treated with the bactericide. The greater contribution of bacteria to the production of N2O than fungi during the first 48–96 h was possibly due to a faster used of nitrate. Variations in the abundance of bacterial 16S rRNA genes, the ITS region, and the nirK, nirS, norB and nosZI bacterial denitrification genes indicated that the antibiotics used to prevent the growth of bacteria and fungi were effective during incubation. These results suggest that both bacteria and fungi should be considered when designing and applying greenhouse gas mitigation strategies in soils and that their relative contribution to produce N2O and CO2 can vary with time and nitrate availability.

Iodine Biofortification of Apples and Pears in an Orchard Using Foliar Sprays of Different Composition.

Many people across the world suffer from iodine (I) deficiency and related diseases. The I content in plant-based foods is particularly low, but can be enhanced by agronomic biofortification. Therefore, in this study two field experiments were conducted under orchard conditions to assess the potential of I biofortification of apples and pears by foliar fertilization. Fruit trees were sprayed at various times during the growing season with solutions containing I in different concentrations and forms. In addition, tests were carried out to establish whether the effect of I sprays can be improved by co-application of potassium nitrate (KNO3) and sodium selenate (Na2SeO4). Iodine accumulation in apple and pear fruits was dose-dependent, with a stronger response to potassium iodide (KI) than potassium iodate (KIO3). In freshly harvested apple and pear fruits, 51% and 75% of the biofortified iodine was localized in the fruit peel, respectively. The remaining I was translocated into the fruit flesh, with a maximum of 3% reaching the core. Washing apples and pears with running deionized water reduced their I content by 14%. To achieve the targeted accumulation level of 50–100 μg I per 100 g fresh mass in washed and unpeeled fruits, foliar fertilization of 1.5 kg I per hectare and meter canopy height was required when KIO3 was applied. The addition of KNO3 and Na2SeO4 to I-containing spray solutions did not affect the I content in fruits. However, the application of KNO3 increased the total soluble solids content of the fruits by up to 1.0 °Brix compared to the control, and Na2SeO4 in the spray solution increased the fruit selenium (Se) content. Iodine sprays caused leaf necrosis, but without affecting the development and marketing quality of the fruits. Even after three months of cold storage, no adverse effects of I fertilization on general fruit characteristics were observed, however, I content of apples decreased by 20%.

Species-specific responses of “Critically Endangered” and “Least Concern” Aloe seed germination to environmental conditions in Tanzania

The majority of Aloe species are threatened by anthropogenic activities, trade, and the effects of climate change, but little is known on seed biology and appropriate conservation measures. Hence, understanding the germination behaviour of Aloe species will help in mitigating the negative effect of changing environmental conditions. “Critically Endangered” (A. boscawenii and A. pembana) and “Least Concern” (A. lateritia, A. volkensii and A. secundiflora) Aloe species’ seed germination was tested under various environmental parameters which are said to be crucial for Aloe species seed germination and included treatments of possible climate change scenarios. We varied temperature, light, scarification, KNO3 addition and salinity and compared the response of the “Critically Endangered” versus the “Least Concern” Aloe species. “Least Concern” Aloe species were used as a control because they have adapted to a wide range of environmental conditions in contrast to “Critically Endangered” Aloe species, which often have a restricted range and specific environmental needs. All Aloe species germinated best at moderate temperatures (25 °C–30 °C) and low KNO3 levels (0.01 mg/l). Dark conditions triggered higher germination percentages for all Aloe species except for A. boscawenii. Saline water suppressed the germination of all Aloe species compared to Aloe species grown in distilled water medium only. Aloe seeds grown in filter paper distilled water medium germinated better than Aloe seeds grown on a soil medium. The “Least concern” (IUCN Red List) A. lateritia germinated better than other species, followed by “Critically endangered” A. pembana and A. secundiflora. Generally, Aloe seed germination is nurtured by moderate temperatures and low concentrations of KNO3. Hence, the effect of global warming will affect the survival of most Aloe species. The better germination performance under shade highlights the importance of parent plants, or at least a healthy canopy cover, in the Aloe species habitat. Aloe seeds showed species-specific responses to various environmental conditions (except for A. pembana), which reflects their Red List status.

PENGARUH PENAMBAHAN KALIUM NITRAT DALAM LARUTAN HARA PADA MEDIA KASCING TERHADAP PERTUMBUHAN SELADA (Lactuca sativa L.)

This research was conducted with the aim to find out the effect of the addition of potassium nitrate in lettuce as a medium and critical level of concentration(electrical conductivity)of nutrient solution. Research is organized in the form of a pot experiment. The experimental design used was Complete RandomizedBlock Design (CRBD)) with three replications. The treatment consists of 12 levels of concentrations or nutrient solution electrical conductivity with the addition of potassium nitrate to lettuce plant. The treatment level of concentrations (conductivity) of nutrient is as follows; L0 = 0.00; L1 = 1.25; L2 = 2.50; L3 = 3.75; L4 = 5.00; L5 = 6.25; L6 = 7.50; L7 = 8.75; L8 = 10.00; L9 = 11.25; L10 = 12.50 and L1 = 13, 75 g 100 L-1 water. Value concentrations of electrical conductivity each nutrient solution concentrations are: L0 = 0.06; L1 = 0.26; L2 = 0.46; L3 = 0.66; L4 = 0.86; L5 = 1.06; L6 = 1.26; L7 = 1,46; L8 = 1.66; L9 = 1,86; L10 = 2.06 and L1 = 2.26. dS m-1. The result of the experiment showed that addition of KNO3 highly significant effect on the increase in fresh weight and dry weight of shoot per plant. Fresh weight and oven-dry weight of shoot per plant was significantly increased in a quadratic with increasing concentrations of KNO3are optimum for growth of plant shoot weight were at 12.23 g in 100/of water on electrical conductivity equivalent to 2.01 dS.m-1. The addition of concentration of KNO3to nutrient solution does not affect on N and other nutrient solution on shoot tissue of lettuce plant but the concentrations of P and K in plant shoot tissue were significantly increased linearly with the provision of KNO3.

Investigation on the Ca(OH)2/CaO thermochemical energy storage system with potassium nitrate addition

Thermochemical energy storage system (TCES) is a novel generation of concentrated solar power (CSP) heat storage system, which has the characteristics of higher heat storage density and long-term heat storage. Ca(OH)2 is a low-cost and widely available material with great application prospects, especially in CSP system because of the suitable heat storage temperature. This research focuses on improving the heat storage efficiency of Ca(OH)2/CaO TCES system by KNO3 addition. In order to further study the effect of KNO3 addition on Ca(OH)2/CaO heat storage process, the kinetic analysis of the thermal storage process of pure and KNO3 added Ca(OH)2 was carried out and the kinetic control equations were obtained, which can provide guidance for the design of the Ca(OH)2/CaO TCES system. Results show that 10 wt% KNO3 addition can reduce the heat storage temperature to 428.49 °C and greatly accelerate the reaction with nearly no loss of heat storage density. The cycling stability of the pure as well as KNO3 added Ca(OH)2/CaO system was investigated in air and nitrogen atmospheres. The failure process of the KNO3 added Ca(OH)2/CaO in air atmosphere is revealed and it is verified that the composite material has a good cyclic stability in nitrogen atmosphere.

Nitrate Promotes Germination Under Inhibition by NaCl or High Concentration of Glucose.

Seed germination, one of the most important stages in a plant’s life cycle, can be affected by abiotic stresses, such as salinity. The plant hormone abscisic acid (ABA) and high concentrations of glucose are also known to inhibit germination. In contrast, nitrate is known to stimulate germination in many plants. However, this stimulatory effect has not yet been investigated in the presence of inhibitory effects caused by abiotic stresses, ABA, and glucose. In this study, we show that nitrate can alleviate the inhibitory effects of sodium chloride (NaCl) or high concentrations of glucose on seed germination in Arabidopsis, while it was not able to promote germination that was inhibited by exogenous ABA and mannitol (an inducer of osmotic stress). An analysis of the gene expression involved in the regulation of germination showed that GA20ox1, encoding the gibberellin (GA) synthesis enzyme, SPATULA (SPT), encoding a bHLH transcription factor, and CYP707A2, encoding an ABA catabolic enzyme, were significantly upregulated by the addition of KNO3 in the presence of NaCl or glucose. Our results suggest the possibility that these genes are involved in the nitrate-mediated control of seed germination in the presence of NaCl or glucose.

Association behavior and fluorescence quenching between cationic zinc porphyrin pendant groups on water-soluble polymers and anionic iron porphyrin guests

An amphiphilic cationic tripyridiniumylporphyrin monomer, i.e., ZnTrMPyP, was synthesized and copolymerized with acrylamide in water and dimethyl sulfoxide, respectively, to prepare the water-soluble random copolymer P-D and microblock copolymer P-W. The association behavior and fluorescence quenching between the copolymers and tetra(p-sulfonato phenyl)porphyrin (Fe(III)TSPP(Cl)) were studied via absorption and emission spectra. The results showed that relatively discrete pendant groups of ZnTrMPyP within P-D could form a ground state complex with FeTSPP by electrostatic interactions, and both static and dynamic mechanisms were active in this quenching process. In contrast, the microblock porphyrin pendant groups within P-W interacted with FeTSPP as an entity, and static quenching was dominant in this process. Salt effects on the formation of the copolymers and FeTSPP complex were also investigated through the addition of KNO3, and the results showed that this association can be weakened by the electrostatic shielding effect, and the fluorescence quenching constant could be reduced.

Utilization of sugarcane industry effluent for high value biomass and photosynthetic pigments production of Chlorella vulgaris (PSBDU06)

A huge amount of pollutant free water required for sugarcane processing industry to obtain sugarcane byproducts. It is estimated that approximately 1–2 m3 of water being used to practice 1 ton of sugarcane and this process will generate 1 m3 as polluted effluent. This work has been dealt with treating sugarcane industry (SCI) effluent by bio cultivation of Chlorella vulgaris (PSBDU06). The cultivation of C. vulgaris in SCI effluent was also evaluated by dilution of effluent and adding external nutrient sources. The addition of KNO3 and 10% WW dilution resulted higher nutrients consumption (PO3−4-93.67 ± 4.69%, NO−3-66.33 ± 3.32%, NO−2-64.21 ± 3.21%, SiO32—83.49 ± 4.17%), than others. The higher biomass (6.85 ± 0.34 g L−1) and photosynthetic pigments (2.87 ± 0.14 μg L−1) production could be achieved at a 10% WW and potassium nitrate combination. The combined bio cultivation of C. vulgaris with external additional nutrients sources with lowest dilution of SCI effluent shows excellent removal of nutrients and high value algal products achieved.

Interaction of Na9[SbW9O33] with Iridium(IV) Hydroxo Complexes

Thermostating of the aqueous solution of Na9[SbW9O33] with K2[Ir(OH)6] at 70 °C for 17 h changes the solution’s color from blue to brown. The addition of KNO3 to the reaction solution and subsequent evaporation in air causes crystallization of the products to yield yellow crystals of composition K5.47Na2.3[Ir0.17Sb0.83W6O24](NO3)0.6·12H2O containing an Anderson-type anion $${[{\rm{S}}{{\rm{b}}^{\rm{V}}}{\rm{W}}_6^{{\rm{VI}}}{{\rm{O}}_{24}}]^{7 - }}$$ with ∼20% of antimony positions occupied by iridium.

Influence of edaphic conditions and nitrogen fertilizers on cadmium and zinc phytoextraction efficiency of Noccaea caerulescens

The success of cadmium phytoextraction operations with Noccaea caerulescens varies by a factor of 70 between sites of trials. However, soil factors driving the efficiency of cadmium (Cd) and zinc (Zn) phytoextraction are still poorly understood, as are the effects of nitrogen fertilizers. We studied biomass production and Cd and Zn uptake by two contrasting populations of N. caerulescens, Ganges (metallicolous) and Wilwerwiltz (non-metallicolous) grown in pots on a range of 24 field contaminated soils for 20 weeks. The addition of KNO3 and NH4NO3 fertilizers was also tested. Using model averaging of multiple regression models, we show that the major drivers of N. caerulescens growth are physical soil factors such as organic matter and soil bulk density while trace metal accumulation mainly relies on soil Cd and Zn exchangeable concentrations. We confirm the negative effect of soil copper (Cu) on growth, even at exchangeable concentrations below 30 mg kg−1, and therefore on uptake efficiency, while increasing soil lead (Pb) content was related to increased biomass probably due to a protective effect against soil pathogens. Finally, there is a small positive effect of nitrogen fertilization on biomass production only in soils with low initial nitrogen content (under 25 μg g−1 NO3−), while above this value, the positive impact of initial nitrogen content is offset by lower shoot Cd and Zn concentrations. Our data bring substantial information regarding the physico-chemical properties to ensure N. caerulescens growth: a soil bulk density under 1.05 kg/dm3, organic matter above 7% and pH under 7.5. We show that phytoextraction efficiency is maximal for moderate soil contamination in Cd (2–10 mg kg−1) and Zn (300–1000 mg kg−1).

Greenhouse Gas Emissions from Paddy Soils Respond to Different Crop Root Residues and N Fertilizer Types

Greenhouse gas emissions from paddy soils respond differently to different combinations of crop root residues and N forms. An incubation experiment was carried out to explore the effect of four crop residues (milk vetch, ryegrass, winter wheat, and rape) and four nitrogen treatments (without fertilizer, urea, (NH4)2SO4, and KNO3) on CH4, CO2, and N2O emissions in a paddy soil. Except in KNO3 application treatments, CH4 emissions of milk vetch residue treatments were significantly higher than those of the rest residue treatments. In the presence of milk vetch and ryegrass residues, urea application significantly increased CH4 emissions in comparison to treatments without fertilizer. Urea significantly promoted CO2 emissions, whereas (NH4)2SO4 and KNO3 significantly inhibited CO2 emissions at all root residue treatments. Urea did not increase N2O emissions, but (NH4)2SO4 and KNO3 promoted N2O emissions at all residue treatments. In addition, KNO3 had more effects on the increase of N2O emissions than (NH4)2SO4 in milk vetch-amended soils. Urea addition had no effect on global warming potentials, and (NH4)2SO4 and KNO3 addition significantly increased global warming potentials at all residue treatments except KNO3 + winter wheat residue combination. Our results indicated that urea application had no additive effect on global warming when root residues were left in paddy soils, whereas (NH4)2SO4 and KNO3 application could increase the risk of global warming.

Evaluating the effect of liming on N2O fluxes from denitrification in an Andosol using the acetylene inhibition and 15N isotope tracer methods

We assessed the effect of liming on (1) N2O production by denitrification under aerobic conditions using the 15N tracer method (experiment 1); and (2) the reduction of N2O to N2 under anaerobic conditions using the acetylene inhibition method (experiment 2). A Mollic Andosol with three lime treatments (unlimed soil, 4 and 20 mg CaCO3 kg−1) was incubated at 15 and 25 °C for 22 days at 50% and then 80% WFPS with or without 200 mg N kg−1 added as 15N enriched KNO3 in experiment 1. In experiment 2, the limed and unlimed soils were incubated under completely anaerobic conditions for 44 h (with or without 100 mg N kg−1 as KNO3). In experiment 1, limed treatments increased N2O fluxes at 50% WFPS but decreased these fluxes at 80% WFPS. At 25 °C, cumulative N2O and 15N2O emissions in the high lime treatment were the lowest (with at least 30% less 15N2O and total N2O than the unlimed soil). Under anaerobic conditions, the high lime treatment showed at least 50% less N2O than the unlimed treatment at both temperatures with or without KNO3 addition but showed enhanced N2 production. Our results suggest that the positive effect of liming on the mitigation of N2O evolution from soil was influenced by soil temperature and moisture conditions.

Contrasting effects of NH4+ and NO3− amendments on amount and chemical characteristics of different density organic matter fractions in a boreal forest soil

Elevated nitrogen (N) deposition variously affects the soil carbon (C) cycle. It is not clear how deposited NH4+ and NO3− divergently affect the amount and stability of soil organic C (SOC) in the N-limiting forests. A multi-form N addition experiment was conducted in a boreal forest in the Great Khingan mountain in 2010. Three fertilizers, NH4Cl, KNO3 and NH4NO3, were applied at four rates of 0, 10, 20, and 40kgNha−1yr−1. Solid-state 13C nuclear magnetic resonance spectroscopy and elemental analysis were used to determine the chemical structure and C contents in bulk soils and/or two density fractions (<1.70gcm−3 light fraction and >1.70gcm−3 heavy fraction). NH4Cl addition significantly decreased the SOC contents in the organic layer by 28.35% to 54.23%, but KNO3 addition significantly increased the SOC contents in the organic layer and mineral layer by 26.53% and 87.44%, respectively. Nitrogen addition rates significantly influenced the degradability (alkyl-C/O-alkyl-C) and hydrophobicity ((alkyl C+aromatic C)/(O-alkyl C+carboxyl C)) of light and heavy fractions, whereas N addition forms only impacted their aromaticity (aromatic C/(aromatic C+alkyl C+O-alkyl C)). The movement between residue-C and stable humin fraction, as well as the chemical stability of SOM could profoundly affect the storage of SOC under N enrichment. Overall, added NH4+ and NO3− differently affect C sequestration in the N-limiting forest soils. This should be differentiated in the biogeochemical models of CN cycle coupling.

森林土壤融化期异养呼吸和微生物碳变化特征

PDF HTML阅读 XML下载 导出引用 引用提醒 森林土壤融化期异养呼吸和微生物碳变化特征 DOI: 10.5846/stxb201511162320 作者: 作者单位: 中国科学院大气物理研究所,中国科学院大气物理研究所,中国科学院大气物理研究所,长安大学地球科学学院,Faculty of Agriculture, Yamagata University, Tsuruoka, Japan 作者简介: 通讯作者: 中图分类号: 基金项目: 国家自然科学基金（41175133，21228701，41275166，41321064，41575154） Changes in heterotrophic respiration and microbial biomass carbon of forest soils during thaw Author: Affiliation: Institute of Atmospheric Physics, Chinese Academy of Sciences,Institute of Atmospheric Physics, Chinese Academy of Sciences,Institute of Atmospheric Physics, Chinese Academy of Sciences,College of Earth Science and Resources, Chang'an University, Fund Project: 摘要 | 图/表 | 访问统计 | 参考文献 | 相似文献 | 引证文献 | 资源附件 | 文章评论 摘要:采用室内土柱培养的方法，研究在不同湿度（55%和80% WFPS，土壤充水孔隙度）和不同氮素供给（NH4Cl和KNO3，4.5 g N/m2）条件下，外源碳添加（葡萄糖，6.4 g C/m2）对温带成熟阔叶红松混交林和次生白桦林土壤融化过程微生物呼吸和微生物碳的激发效应。结果表明：在整个融化培养期间，次生白桦林土壤对照CO2累积排放量显著高于阔叶红松混交林土壤。随着土壤湿度的增加，次生白桦林土壤对照CO2累积排放量和微生物代谢熵（qCO2）显著降低，而阔叶红松混交林土壤两者显著地增加（P < 0.05）。两种林分土壤由葡萄糖（Glu）引起的CO2累积排放量（9.61-13.49 g C/m2）显著大于实验施加的葡萄糖含碳量（6.4 g C/m2），同时由Glu引起的土壤微生物碳增量为3.65-27.18 g C/m2，而施加Glu对土壤DOC含量影响较小。因此，这种由施加Glu引起的额外碳释放可能来源于土壤固有有机碳分解。融化培养结束时，阔叶红松混交林土壤未施氮处理由Glu引起的CO2累积排放量在两种湿度条件下均显著大于次生白桦林土壤（P < 0.001）；随着湿度的增加，两种林分土壤Glu引起的CO2累积排放量显著增大（P < 0.001）。单施KNO3显著地增加两种湿度的次生白桦林土壤Glu引起的CO2累积排放量（P < 0.01）。单施KNO3显著地增加了两种湿度次生白桦林土壤Glu引起的微生物碳（P < 0.001），单施NH4Cl显著地增加低湿度阔叶红松混交林土壤Glu引起的微生物碳（P < 0.001）。结合前期报道的未冻结实验结果，发现冻结过程显著地影响外源Glu对温带森林土壤微生物呼吸和微生物碳的刺激效应（P < 0.05），并且无论冻结与否，温带森林土壤微生物呼吸和微生物碳对外源Glu的响应均与植被类型、土壤湿度、外源氮供给及其形态存在显著的相关性。 Abstract:Packed soil core incubation experiment was made to study the effects of external carbon (C) (glucose, 6.4 g C/m2) addition on microbial respiration and microbial biomass C (MBC) in soils of a mature broadleaf and Korean pine mixed forest (BKPF) and an adjacent white birch forest (WBF) during thaw under different soil moisture levels (55% and 80% water-filled pore space) and nitrogen (N) supply (NH4Cl and KNO3, 4.5 g N/m2). The results showed that, without C and N addition, cumulative CO2 flux from the WBF soil was significantly higher than that from the BKPF soil during the incubation period. With increasing soil moisture, the cumulative CO2 flux and microbial metabolic quotient (qCO2) decreased in the WBF soil but increased in the BKPF soil without C and N addition(P < 0.05). The glucose-induced cumulative CO2 fluxes from the two forest soils ranged from 9.61 to 13.49 g CO2-C/m2, which was greater than the dose of added C in the form of glucose. The glucose-induced MBC in the two forest soils ranged from 3.65 to 27.18 g C/m2, while glucose addition had little impact on soil dissolved organic C pool. Hence, the extra C released upon addition of glucose may result from the decomposition of soil native organic C. Without N addition and under the two soil moisture levels, the glucose-induced cumulative CO2 flux from the BKPF soil was significantly higher than that from the WBF soil during thaw (P < 0.001). With increasing soil moisture, the glucose-induced cumulative CO2 fluxes from the two forest soils were significantly increased (P < 0.001). The addition of KNO3 alone significantly increased the glucose-induced cumulative CO2 flux (P < 0.01) and the glucose-induced MBC (P < 0.001) in the WBF soil under two soil moisture levels (P < 0.001). Addition of NH4Cl alone significantly increased the glucose-induced MBC in the BKPF soil with low moisture level. Based on the results from the previously reported non-freezing experiments and the results of the present study, it can be concluded that freezing treatment significantly affects the stimulating effects of glucose on soil microbial respiration and MBC under temperate forests. Regardless of whether freezing occurred or not, the responses of soil microbial respiration and MBC to the addition of extraneous C as glucose in temperate forests depend on vegetation type, soil moisture, and the amount and type of N added. 参考文献 相似文献 引证文献

Effects of the addition of nitrogen and sulfate on CH4 and CO2 emissions, soil, and pore water chemistry in a high marsh of the Min River estuary in southeastern China.

Exogenous nitrogen (N) and sulfate (SO42-), resulting from human activity, can strongly influence the emission of CH4 and CO2 from soil ecosystems. Studies have reported the effects of N and SO42- on CH4 and CO2 emissions from inland peatlands and paddies. However, very few studies have presented year-round data on the effects of the addition of N and SO42- on CH4 and CO2 emissions in estuarine marshes. The effects of the addition of N and SO42- on the emission of CH4 and CO2 were investigated in a Cyperus malaccensis marsh in the high tidal flat of the Min River estuary of southeastern China from September 2014 to August 2015. Dissolved NH4Cl, KNO3, and K2SO4 were applied every month, in doses of 24gN/SO42-m-2·yr-1. The emission of CH4 and CO2 showed distinct monthly and seasonal variations. Compared with the control, the addition of NH4Cl and NH4NO3+K2SO4 showed increases in CH4 fluxes (p<0.05), while the effects of the addition of KNO3 and K2SO4 on CH4 were minor (p>0.05). NH4Cl had a positive impact on CO2 emissions (p<0.01), while the addition of KNO3, K2SO4, and NH4NO3+K2SO4 had minor positive impacts, compared to the control (p>0.05). Correlation analysis found that soil sulfate concentration, nitrogen availability and enzyme activity were the dominant factors influencing CH4 and CO2 variation. Our findings suggest that CH4 and CO2 emissions were influenced more by ammonium than by nitrate. We propose that the suppressive effect of additional sulfate on CH4 production is insignificant, due to which the inhibition may be overestimated in the estuarine brackish marsh.

Elaboration and microstructural characterization of calcareous/ceria based composite on zinc substrate

Cerium conversion coatings were prepared by cathodic electrodeposition from a low concentrated aqueous solution of Ce(NO3)3 with KNO3 addition to insure the conductivity of the electrolyte. The cerium oxide film was characterized by Scanning Electronic Microscopy (SEM). Although the deposit is uniform with current density of 2 mA/cm2, it shows cauliflower morphology with a crack network, giving rise to bad mechanical and electrochemical behaviour. Elaboration of a calcareous deposit inside crack network of the cerium coating by cathodic polarization from artificial seawater is investigated at different applied potential, in order to increase the quality of the cerium coating formed. For cathodic potentials lower than–1.5 V/SCE, zinc corrosion products (gordaite) were observed inside the cerium oxide film instead of calcareous deposit although the current density decrease during the deposition suggesting a partially blocked surface. A pure calcareous compound was observed at–1.5 and–1.6 V/SCE. SEM and EDX cartography of the cross section revealed that open cracks in the cerium oxide structure are filled by calcium. Calcium was also detected inside the CeO2 film not only all around the cracks but also in all the porosity of the CeO2 film. It has precipitated as CaCO3 (aragonite form) as revealed by micro-Raman spectroscopy and XRD.

Synergistic effects of dissolved organic carbon and inorganic nitrogen on methane uptake in forest soils without and with freezing treatment.

There is limited knowledge about how the interaction of dissolved organic carbon (DOC) and inorganic nitrogen (N) released into the soil just after freezing can affect methane (CH4) uptake in forest soils. Here, we present how freezing treatment and glucose, as a DOC source, can affect the roles of NH4+-N and NO3−-N in inhibiting soil CH4 uptake, by using soil-core incubation experiments. A long-term freezing at low temperature reduced cumulative CH4 uptake in the soils sampled from two temperate forest stands without carbon (C) and N addition. The inhibition effects of N addition as NH4Cl and KNO3 on the soil CH4 uptake were much larger than C addition. Freezing treatment eliminated the inhibition effect of NH4Cl and KNO3 addition on CH4 uptake, and this response was affected by glucose addition and forest types. The addition of glucose eliminated the inhibition effect of NO3−-N on CH4 uptake in the forest soils without and with freezing treatment, while the addition of NH4+-N and glucose inhibited synergistically the soil CH4 uptake. The results highlight the importance of synergistic effects of DOC and N inputs on the soil CH4 uptake under forest stands during soil wetting and thawing periods.

Enhanced photocatalytic activity of titania in the presence of KNO3 on the photodegradation of dyes

Pristine TiO2 nanoparticles were synthesized using the sol-gel method. Morphological and size distribution patterns of the photocatalyst were determined using transmission electron microscopy, scanning electron microscopy and Brunuer-Emmett-Teller (BET) technique. Raman spectroscopy and powder X-ray diffraction were carried out to yield structural composition of TiO2. The photocatalyst was further used to photodegrade bromophenol blue (BPB) and methyl orange (MO), two anionic dyes, in the presence of KNO3. The addition of KNO3 improved the photodegradation of the dyes. The highest dye removal was observed after the addition of 5mgL−1 of KNO3. The effect of pH upon the removal of the dyes was studied. Over 80% of BPB was removed, while 40% of MO was removed at pH 1. The results gave good correlation between radical-scavenging and improved photoactivity. Increased radical-scavenging effect was measured by the decrease of DPPH at 517nm.

Efeito da Temperatura e do KNO3 na Germinação de Acnistus arborescens (Solanaceae)

RESUMO A propagação de Acnistus arborescens (fruto-do-sabiá) usualmente é feita através de estacas, devido a baixa taxa de germinação de suas sementes. O objetivo deste trabalho foi estudar o efeito da temperatura e do estimulante nitrato de potássio (KNO3) na germinação do fruto-do-sabiá. O experimento foi realizado utilizando quatro regimes de temperatura (20, 25, 30 e 20-30 °C), com e sem nitrato de potássio, em delineamento inteiramente casualizado com quatro repetições de 50 sementes cada. Foram avaliados a porcentagem, o índice de velocidade e o tempo médio de germinação. Nas temperaturas constantes, o KNO3 favoreceu a germinação, sendo as maiores porcentagens (&gt;68%) obtidas nas temperaturas de 20 °C e 25 °C. A temperatura alternada de 20-30 °C aumentou a porcentagem de germinação, sem a adição de KNO3, portanto além da propagação vegetativa. A produção de mudas a partir de sementes é viável.

Sediment Denitrification and Nutrient Fluxes in the San José Lagoon, a Tropical Lagoon in the Highly Urbanized San Juan Bay Estuary, Puerto Rico

Direct measurements of net N2 production, oxygen, and inorganic nutrient fluxes at the sediment–water interface were conducted in the San Jose Lagoon (SJL), a tropical coastal lagoon located at the San Juan Bay Estuary, Puerto Rico, that is heavily impacted by anthropogenic activities. Sediment of the SJL had high organic matter (average = 16.7 %; SD = 9.0), pore water ammonium (541 μM ± 422), and pore water soluble reactive phosphorus (SRP) (57 μM ± 48) concentrations. High fluxes of oxygen (−1999 μmol m−2 h−1 ± 2180) and N2–N (192 μmol m−2 h−1 ± 315) fluxes were observed. Similarly, high fluxes of ammonium (770 μmol m−2 h−1 ± 701) and SRP fluxes (167 μmol m−2 h−1 ± 138) were measured, with moderate nitrate fluxes (−40 μmol m−2 h−1 ± 53) mostly directed into the sediment. The dissolved inorganic nitrogen and soluble reactive phosphorus ratio (DIN/SRP) was low relative to the Redfield ratio and suggested that the sediment would support SJL as a nitrogen-limited system. An experiment with higher nitrate concentration resulted in a significant response (p < 0.05) of denitrifying microbes and ammonium fluxes to a 100-μM KNO3 addition. Net N2 production was an important sink in the nitrogen balance of the SJL, though most remineralized N was released as ammonium. Efforts to mitigate eutrophication in the SJL require consideration of the substantial role that sediments play in biogeochemical cycles.