Mitigation of carbon dioxide and nitrous oxide emissions from soil: Elucidating the impacts of nitrification inhibitors, environmental factors, soil characteristics and biogas residues acidification

The mineral N fertilizer (NH4+) and the organic N fertilizer (biogas residues) applied to fertilize soils may lead to higher CO2 and N2O emissions. Nitrification inhibitors (NIs) and chloride are used to curb this effect. However, their effectiveness is strongly influenced by environmental factors, soil and fertilizer properties. This study investigated how different NIs and chlorides behave under different environmental factors, soil and fertilizer properties. In an incubation experiment the efficacies of four NIs (DCD, DMPP, ENTEC and PIADIN) and two chlorides (KCl and MgCl2) under different environmental factors (two soil temperatures (15 and 25 °C), two moisture levels (60% and 80% water holding capacity)), three types of soils (clay, loam and sand) and two types of fertilizer (biogas residues and acidified biogas residues) were tested for 8 weeks. The soil received 0.5 g NH4+-N kg-1 soil and the inhibitors were applied at 5% of the applied N. KCl and MgCl2 were applied at 0.5 and 1.0 g kg-1, respectively. The results of this study show that DMPP and PIADIN were more effective than DCD and ENTEC in inhibiting nitrification in sandy soils at 15 and 25 °C and at 60% and 80% water holding capacity. The efficacy of all nitrification inhibitors improved with increasing soil moisture, while increasing temperatures had various negative effects on the sandy soil used. 1.0 g kg-1 MgCl2 reduced both CO2 and N2O emissions. The acidified biogas residues had less influence on the increased CO2 and N2O emissions compared to the unacidified biogas residues. DMPP and PIADIN were able to significantly reduce the emissions of CO2 and N2O compared to the control treatment when applied as biogas residues and acidified biogas residues. DCD reduced CO2 and N2O emissions in clay and loam soil. DMPP and PIADIN reduced N2O emissions in sandy soil. ENTEC increased N2O emissions in clay, loam and sandy soils. The NIs, MgCl2 amendment and acidification of biogas residues are useful to increase fertilizer use efficiency and to mitigate CO2 and N2O emissions. If the soil contains more clay, DCD is more efficient. If the soil contains more sand, strong inhibition occurs with DMPP. It was demonstrated in the present study that efficacy of nitrification inhibitors strongly depends on soil texture

Catalytic asymmetric carbon-carbon bond forming methodologies for synthesis of chiral N-containing heterocycles and chiral carboxamides

In this thesis, we have developed several strategies that allow the Cu-catalyzed asymmetric conjugate addition of Grignard reagents to various heterocyclic substrates, such as 2- quinolones, 4-pyridone, 2,3-dihydro-4-pyridone, 2-quinolones and N-acylpyridinium salts. In addition, we have demonstrated that Lewis acids are highly beneficial for such reactions and can be successfully employed to activate the corresponding acceptors towards nucleophilic additions, as well as control the selectivities in these reactions

Copper-catalysed alkylation of heterocyclic acceptors with organometallic reagents

Copper-catalysed asymmetric C-C bond-forming reactions using organometallic reagents have developed into a powerful tool for the synthesis of complex molecules with single or multiple stereogenic centres over the past decades. Among the various acceptors employed in such reactions, those with a heterocyclic core are of particular importance because of the frequent occurrence of heterocyclic scaffolds in the structures of chiral natural products and bioactive molecules. Hence, this review focuses on the progress made over the past 20 years for heterocyclic acceptors

Highly Enantioselective Catalytic Addition of Grignard Reagents to N-Heterocyclic Acceptors

General methods to prepare chiral N-heterocyclic molecular scaffolds are greatly sought after because of their significance in medicinal chemistry. Described here is the first general catalytic methodology to access a wide variety of chiral 2- and 4-substituted tetrahydro-quinolones, dihydro-4-pyridones, and piperidones with excellent yields and enantioselectivities, utilizing a single catalyst system

Phase Equilibria and Phase Separation of the Aqueous Solution System Containing Lithium Ions

Brines including seawater, concentrated seawater after desalinization, salt lake, oil/gas water, and well bitter are widely distributed around the world. In order to promote the comprehensive utilization and effective protection of the valuable chemical resources existing in brines such as freshwater, lithium, sodium, potassium, and magnesium salts, the systematic foundation and application foundation research including phase equilibria and thermodynamic properties for the salt‐water electrolyte solution are essential, especially for solid lithium salts and their aqueous solution systems

Comparative Effectiveness of Four Nitrification Inhibitors for Mitigating Carbon Dioxide and Nitrous Oxide Emissions from Three Different Textured Soils

Nitrification inhibitors (NIs) can be used to reduce both NO3−-N leaching and N2O-N emissions. However, the comparative efficacies of NIs can be strongly affected by soil type. Therefore, the efficacies of four nitrification inhibitors (dicyandiamide (DCD), 3, 4-dimethylpyrazole phosphate (DMPP), nitrogenous mineral fertilizers containing the DMPP ammonium stabilizer (ENTEC) and active ingredients: 3.00–3.25% 1, 2, 4-triazole and 1.50–1.65% 3-methylpyrazole (PIADIN)) were investigated in three different textured N-fertilized (0.5 g NH4+-N kg−1 soil) soils of Schleswig-Holstein, namely, Marsch (clayey), Östliches Hügelland (loamy) and Geest (sandy) under a controlled environment. Total CO2-C and N2O-N emissions were significantly higher from Marsch than Östliches Hügelland and Geest. In Marsch, DMPP showed the highest inhibitory effect on CO2-C emission (50%), followed by PIADIN (32%) and ENTEC (16%). In Östliches Hügelland, DCD and PIADIN showed the highest and equal inhibitory effect on CO2-C emission (73%), followed by DMPP (64%) and ENTEC (36%). In Marsch and Östliches Hügelland, DCD showed the stronger inhibitory effect on N2O-N emission (86% and 47%) than DMPP (56% and 30%) and PIADIN (54% and 16%). In Geest, DMPP was more effective in reducing N2O-N emission (88%) than PIADIN (70%) and DCD (33%). Thus, it can be concluded that DCD is a better NI for clay and loamy soils, while DMPP and PIADIN are better for sandy soils to inhibit soil nitrification and gaseous emissions

Impact of different chloride salts and their concentrations on nitrification and trace gas emissions from a sandy soil under a controlled environment

Potassium chloride (KCl) and magnesium chloride (MgCl2) can be used to reduce carbon dioxide (CO2) and nitrous oxide (N2O) emissions, but their efficacy can be strongly affected by their Cl− concentration. This study aimed to compare the behaviour of different Cl− salts and concentrations with that of a typical commercial nitrification inhibitor (3, 4-dimethylpyrazole phosphate, PIADIN). KCl, MgCl2 and PIADIN were investigated under a laboratory incubation experiment for two months. KCl and MgCl2 were applied at 0.5 and 1.0 g kg−1, while PIADIN was applied at 25 mg kg−1 soil. CO2 and N2O concentrations were analysed during the incubation period. The NH+4 and NO−3 dynamics in soil were also measured. The results showed 0.5 and 1.0 g kg−1 KCl and 0.5 g kg−1 MgCl2 decreased CO2-C emissions by 43%–46% and increased N2O-N emissions by 15%–48%, whereas 1.0 g kg−1 MgCl2 decreased CO2-C emissions by 72% and N2O-N emissions by 19%. KCl and MgCl2 retarded the decrease of the NH+4-N concentration and increase of the NO−3-N concentration. PIADIN reduced the emissions of CO2-C by 113% and N2O-N by 97% and maintained a high soil NH+4-N concentration and low NO−3-N concentration. MgCl2 addition at 1.0 g kg−1 was an effective treatment as the Mg both fertilized the soil and inhibited CO2-C and N2O-N emissions. Moreover, 1.0 g kg−1 MgCl2 could retard soil nitrification, the decrease of NH+4-N concentration and the increase of NO−3-N concentration. While PIADIN had no fertilizing value, it was a more effective nitrification inhibitor than Cl− salts

Enantioselective Catalytic Dearomative Addition of Grignard Reagents to 4-Methoxypyridinium Ions

[Image: see text] We describe a general catalytic methodology for the enantioselective dearomative alkylation of pyridine derivatives with Grignard reagents, allowing direct access to nearly enantiopure chiral dihydro-4-pyridones with yields up to 98%. The methodology involves dearomatization of in situ-formed N-acylpyridinium salts, employing alkyl organomagnesium reagents as nucleophiles and a chiral copper (I) complex as the catalyst. Computational and mechanistic studies provide insights into the origin of the reactivity and enantioselectivity of the catalytic process

Limit Equilibrium Method-Based Shear Strength Prediction for Corroded Reinforced Concrete Beam with Inclined Bars

Shear strength is a widely investigated parameter for reinforced concrete structures. The corrosion of reinforcement results in shear strength reduction. Corrosion has become one of the main deterioration factors in reinforced concrete beam. This paper proposes a shear strength model for beams with inclined bars based on a limit equilibrium method. The proposed model can be applied to both corroded and uncorroded reinforced concrete beams. Besides the tensile strength of longitudinal steel bars, the shear capacity provided by the concrete on the top of the diagonal crack, the tensile force of the shear steel at the diagonal crack, the degradation of the cross-sectional area and strength of the reinforcements induced by corrosion are all considered. An experimental work on two groups accelerated corroded beams was performed. Good agreements were found between the proposed theoretical predictions and experimental observations