Yield and Nutrient Uptake of Rapeseed (Brassica campestris var. toria) as Influenced by Phosphorus Sources and Levels in Acidic Soils of Meghalaya

Background: Acidic soils limit the soil phosphorus availability to the crop plants because these soils have tendency to fix P as iron and aluminium phosphate. The present study aims to investigate the influence of phosphorus sources and levels on yield and nutrient uptake of rapeseed (Brassica campestris var. toria) in acidic soils of Meghalaya. Methods: A pot culture experiment was conducted during rabi season of 2016-17 wherein two sources of P (single super phosphate and Mussoorie rock phosphate) and six levels of P (0, 30, 60, 90, 120 and 150 mg P kg-1 of soil) were tested in two types of acidic soils (Alfisols, Inceptisols) in completely randomized design with three replication and rapeseed (cv. M-27) as test crop. Result: The highest mean dry matter yield of rapeseed (16.1 g pot-1) was recorded with 120 mg P kg-1 of soil. Subsequent increase in the level of P significantly decreased the dry matter yield by 4.6% over 120 mg P kg-1. The dry matter yield with Mussorie rock phosphate was lower as compared to single sulphur phosphate (SSP) at each levels of P irrespective of soil type. The concentration of P in plant dry matter of rapeseed increased with each successive levels of P in acidic soils with both P sources; however P uptake increased up to 120 mg P kg-1 soil.

Vapour-Phase Selective O-Methylation of Catechol with Methanol over Metal Phosphate Catalysts

Guaiacol (2-methoxyphenol), an important fine chemical intermediate, is conventionally synthesized by liquid-phase processes with expensive, corrosive and toxic methylating agents such as dimethyl sulphate and dimethyl iodide. Recently, vapour-phase alkylation of catechol (1, 2-dihydroxybenzene) with methanol for the synthesis of guaiacol in the presence of heterogeneous catalysts has received more attention, as the route is economical and environmentally friendly. However, most of the investigated catalysts exhibited unsatisfactory catalytic performance for industrial applications. In this study, five metal phosphates M-P-O (M = La, Ce, Mg, Al, Zn) catalysts were synthesized and tested in the selective O-methylation of catechol with methanol. Among these catalysts, cerium phosphate (CP) showed the highest catalytic activity and guaiacol yield. Lanthanum phosphate (LP) was the second most active, which was still obviously better than magnesium phosphate (MP) and aluminium phosphate (ALP). Zinc phosphate (ZP) was not active in the reaction. Relevant samples were characterized by X-ray diffraction (XRD), Fourier transform infrared (FT-IR), scanning electron microscopy (SEM), N2 adsorption-desorption, temperature programmed desorption of NH3 or CO2 (NH3-TPD, CO2-TPD). The suitable acid-base properties contribute to the superior catalytic performance of CP. Long-term stability and regeneration tests were also studied.

The Phosphate-Based Composite Materials Filled with Nano-Sized BaTiO3 and Fe3O4: Toward the Unfired Multiferroic Materials

The composite material filled with nano-sized BaTiO3 and Fe3O4 was designed and studied. The aluminium phosphate ceramics was used as a matrix. The XRD analysis demonstrates only the crystalline structure of the fillers used. The thermogravimetric analysis proves the thermal stability of the composites up to 950 K. The Maxwell–Wagner relaxation was observed in the dielectric spectra of the investigated composites. The dielectric spectroscopy proves the close contact between the nanoparticles with the different ferroic ordering. The phosphate-based composites have been proved to be a prospective candidate for the multiphase multiferroic materials design and development.

Phosphate supply to the eutrophic lake Eichbaumsee (Germany): Sedimentary versus groundwater sources

<p>The eutrophic lake Eichbaumsee, a ~ 1 km long and 280m wide (maximum water depth 16m) dredging lake southeast of Hamburg (Germany), has been treated for water quality improvements using various techniques (i.e. aeration plants, removal of dissolved phosphate by aluminium phosphate precipitation and by Benthophos adsorption) during the past ~ 15 years. Despite these treatments no long-term improvement of the water quality was observed and the lake water phosphate content continued to increase by e.g. ~ 350 kg phosphate per year between March 2016 and February 2019. As no creeks or rivers drain into the lake and hydrological groundwater models do not suggest any major groundwater discharge into the lake, sources of phosphate (and other nutrients) are unknown.</p><p>We investigated the phosphate fluxes from sediment pore water and groundwater into the water body of the lake. Sediment pore water was extracted from sediment cores recovered by divers in August 2018 and February 2019. Diffusive phosphate fluxes from pore water were calculated based on phosphate gradients using first Fick`s law. Stable water isotopes (δ<sup>2</sup>H, δ<sup>18</sup>O) were measured in the lake water, sediment pore water, interstitial waters in the banks surrounding the lake, the Elbe river and in three groundwater wells close to lake. Stable isotope (δ<sup>2</sup>H, δ<sup>18</sup>O) water mass balance models were used to compute water inflow/outflow to/from the lake.</p><p>Our results revealed pore-water borne phosphate fluxes between – 0.07 mg/m²/d (i.e. slight phosphate uptake by the sediments) and 2.6 mg/m²/d (i.e. phosphate release to the lake). Assuming that the measured phosphate fluxes are temporarily and spatially representative for the whole lake, about 100 kg/a to 220 kg/a of phosphate is released from sediments. This amount is slightly lower than the observed phosphate increase of the lake water. Stable isotope signatures indicate a water exchange between the aquifer and the lake water. Based on stable isotope mass balances (δ<sup>2</sup>H, δ<sup>18</sup>O) we estimate an inflow of phosphate from the aquifer to the lake between 190 kg/a and 1400 kg/a. This inflow indicates that groundwater-born phosphate is as or even more important than phosphate supply via sediment pore-water. Our study suggests that groundwater may have an important impact on lake nutrient budgets.</p>

Developmental Study of Soot-Oxidation Catalysts for Fireplaces: The Effect of Binder and Preparation Techniques on Catalyst Texture and Activity

An awareness of increasing climate and health problems has driven the development of new functional and affordable soot-oxidation catalysts for stationary sources, such as fireplaces. In this study, Al(OH)3, water glass and acidic aluminium phosphate binder materials were mixed with soot-oxidation catalysts. The effect of the binder on the performance of the Ag/La-Al2O3 catalyst was examined, while the Pt/La-Al2O3 catalyst bound with Al(OH)3 was used as a reference. Soot was oxidised above 340 °C on the Ag/La-Al2O3 catalyst, but at 310 °C with same catalyst bound with Al(OH)3. The addition of water glass decreased the catalytic performance because large silver crystals and agglomeration resulted in a blockage of the support material’s pores. Pt/La-Al2O3 bound with Al(OH)3 was ineffective in a fireplace environment. We believe that AgOx is the active form of silver in the catalyst. Hence, Ag/La-Al2O3 was shown to be compatible with the Al(OH)3 binder as an effective catalyst for fireplace soot oxidation.