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Nitrous oxide (N2O) emissions from pasture-based livestock systems represent 34% of Brazil's agricultural greenhouse gas emissions. The forage species Brachiaria humidicola is known for its biological nitrification inhibition (BNI) capacity and N2O emissions reduction ability from urine patches under tropical conditions. However, there is little information about the effect of BNI on N2O emission and ammonia (NH3) volatilisation in the subtropics. This study aimed to (i) evaluate the potential of Brachiaria humidicola, compared with Panicum maximum (Jacq. cv. Áries; guinea grass), a broadly used grass (with no BNI capacity), to reduce N2O emissions under subtropical conditions; (ii) determine the efficacy of nitrification inhibitor dicyandiamide (DCD) to decrease N2O emissions; and (iii) determine the effect of brachiaria and DCD application on NH3 volatilisation. A field experiment was carried out using a Cambisol, where cattle urine ± DCD was applied to brachiaria and guinea grass. Over the 67-day measurement period, cumulative N2O emissions were 20% lower from urine patches in the brachiaria treatment (1138 mg N m-2, Emission factor = 1.06%) compared to guinea grass (1436 mg N m-2, Emission factor = 1.33%) (P .10). Overall, the results demonstrated that brachiaria and DCD use are strategies that can reduce N2O emissions from urine patches. Biochars are widely used to improve soil macropore structures. However, the size-dependent effects of biochars in affecting macropore structure still remain unclear. In this study, the modification of soil macropore structure following biochar addition was investigated by high-resolution X-ray tomography (CT) and advanced data analytical methods. Quantification of soil macropore structure (>52 μm) was based on the intact soil cores (5 cm in diameter and 7 cm in height) collected from biochar-amended paddy soil. The treatments were (a) control (CK), (b) rice straw biochar (RSB), (c) corn straw biochar (CSB), and (d) bamboo biochar (BB). The application rate of biochar was 25 Mg ha-1 (w/w). Results revealed that the biochars affected the soil macropores through both "occupying effect" and "expansion effect". The "occupying effect" means that the biochar particles occupy the original pore space of the soil and reduce the soil porosity, while the "expansion effect" means that the biochar particles produce additional pore space in the soil matrix and increase the soil porosity. For all the biochar treatments in our study, the "occupying effect" was dominated. Therefore, the connected- and isolated porosity of biochar-treated soils were significantly lower than those of CK. The size-dependent effects of biochar in modifying soil macropores were observed. For RSB treatment, the "expansion effect" predominated at the size of 1800 μm. Our results indicated that the effects of biochar on soil macroporosity were dependent on the combined effects the "occupying effect" and "expansion effect". In conclusion, all the biochar types in this study have adverse effects in increasing the soil macroporosity. Silver nanoparticles (Ag NPs) are among the most common forms of nanoparticles in consumer products, yet the environmental implications of their widespread use remain unclear due to uncertainties about their fate. Because sulfidation of Ag NPs results in the formation of a stable silver sulfide (Ag2S) product, it is likely an important removal mechanism of bioavailable silver in natural waters. In addition to sulfide, the complete conversion of Ag NPs to Ag2S will require dissolved oxygen or some other oxidant so dispersed metal sulfides may be an important pool of reactive sulfide for such reactions in oxygenated systems. The reaction of Ag NPs with zinc sulfide (ZnS) was investigated using a voltammetric method, anodic stripping voltammetry (ASV). ASV provided sensitive, in situ measurements of the release of zinc (Zn2+) cations resulting from the cation exchange reaction between Ag NPs and ZnS. The effects of Ag NP size and surface coatings on the initial rates of sulfidation by ZnS were examined. Sulfidation of smaller Ag NPs generally occurred faster and to a greater extent due to their larger relative surface areas. Sulfidation of Ag NPs capped by citrate and lipoic acid occurred more rapidly relative to polyvinylpyrrolidone (PVP) and branched polyethylene (BPEI). This study demonstrates the utility of voltammetry for such investigations and provides insights into important factors controlling Ag NP sulfidation such as availability of dissolved oxygen, Ag NP size and Ag NP surface coating. Furthermore, this work demonstrates the importance of cation exchange reactions between silver and metal sulfides, and how the environmental release of Ag NPs could alter the speciation of other metals of environmental significance. 2,4,6-Trinitrophenol (TNP) has absorbed much concerns because of its toxic effect and threat on the environment, which results from the fact that it is an important and universal reagent widely utilized for manufacturing many products. It is of great necessity to explore facile and efficient methods for monitoring TNP. In present study, carbon dots (CDs), a new carbonaceous nanomaterial with strong fluorescence, was applied to build a novel sensor for highly sensitive and selective detection of TNP. https://www.selleckchem.com/products/Dapagliflozin.html In the sensing procedure, the fluorescence intensity of as-prepared CDs was diminished with the presence of TNP due to inner filter effect (IFE) quenching mechanism. The sensitivity of the fluorescent sensor was very high with limit of detection down to 5.37 ng mL-1. This fluorescent sensor was evaluated and excellent spiked recoveries were gained, which demonstrated that the developed sensor would be a robust tool for environmental applications. NO2 ambient concentrations were measured in a coastal Caribbean city. Barranquilla is a Caribbean city located in the North of Colombia that has approximately 1.200.000 inhabitants and possesses a warm, humid climate. In order to obtain the concentration of the contaminant in an adequate resolution, 137 Passive diffusion tubes from Gradko© were installed. Tubes prepared with 20% Triethanolamine/De-ionised water were located at the roadside between 1 and 5 m from the kerb edge. The sampling period was two weeks, from 3/16/2019 to 3/30/2019. Samples were analyzed on the UV CARY1 spectrophotometer by Gradko©. Results showed an average of 19.92 ± 11.50 μg/m3, with a maximum and minimum value of 70.27 and 0.57 μg/m3, respectively. NO2 correlation with load traffic load was higher than with maximum traffic. The expected results include the analysis of the areas of the city with high concentrations of this pollutant that exceed the limit values established by the WHO in six (6) points; however, they never exceed the local legal limit for annual exposure, which is significantly less restrictive.
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