The Rengen Grassland Experiment (RGE) was established in the Eifel Mts. (Germany) on a low productive Nardetum in 1941. Since then, the following fertiliser treatments have been applied along with a two cut system: unfertilised control,
Ca, CaN, CaNP, CaNP–KCl and CaNP–K2SO4 with basic slag (syn. Thomas phosphate) as the only P fertiliser. The effect of long-term fertilisation on plant-available
(extracted with 0.01 mol l−1 CaCl2), easily-mobilisable (extracted with 0.05 mol l−1 EDTA), potentially-mobilisable (extracted with 2 mol l−1 HNO3) and total concentrations of trace elements (As, Cd, Cr, Cu, Fe, Mn, Ni, Pb and Zn) in the top 0–10 and 10–20 cm of soil
were investigated in 2006. According to redundancy analysis (RDA), the effect of treatment on the concentrations of risk elements
was significant and explained 82.3 and 90.6% of the variability in the data in the 0–10 and 10–20 cm soil layers, respectively.
Basic slag supplied the soil with considerable amounts of As, Cr, Cu, Fe, Mn and Zn. Following 65 years of fertiliser application
the concentrations of risk elements in the soil profile had increased substantially, especially with basic slag. However,
threshold limits for total trace element concentration in soil permitted by Czech national legislation were exceeded only
in the case of As. The increase in plant-available As concentrations was most critical as it increased the potential uptake
of As by plants in plots fertilised with P. Although P treatments received more than 300 g of Cr ha−1 annually, no effect on plant-available Cr soil content was detected. This contrasted with the accumulation of total Cr in
the 0–10 and 10–20 cm soil layers. Furthermore, plant availability of Cd, Fe, Mn and Zn was affected by soil pH and generally
decreased with the application of quick lime. Plant availability of these elements was not correlated with amounts supplied
by fertilisers. 相似文献
The laser deposition of AISI316 powder blended with Cr3C2 over austenitic stainless steel plate was carried out as part of an investigation aimed at determining the feasibility of applying localized reinforcement to stainless steel components. The chromium carbide powder dissolved in the process to produce a range of carbides which reinforced and increased the hardness of the material. The results of optical microscope metallography and SEM/EDX and XRD analysis as well as microhardness measurements are reported. Surfaces produced by deposition of the powder blend were machine-ground and subjected to pin-on-disc and corrosion tests. The tests indicated an improvement to sliding wear resistance and a good resistance to salt spray and pitting corrosion conditions. 相似文献
The polyacrylate anion exchangers are widely used in purification of heavy metal ions from wastewaters and different accompanying complexing agents. Such effluents containing the chelators (EDTA, NTA, HEDTA, DTPA, and IDA) are discharged from relevant industries such as printed circuits boards, plating on plastics, metal finishing and others. The sorption was studied as a function of phase contact time and pH by the batch technique. It was found that the removal of heavy metal ions in the presence of EDTA, NTA and IDA strictly depends on the phase contact time and pH values. Various kinetic models such as the pseudo first-order and the pseudo second-order as well as the intraparticle one were also tested to estimate the sorption rate. The equilibrium capacities of the studied anion exchangers for Cu(II), Zn(II), Co(II), Ni(II), Pb(II) and Cd(II) in the presence of EDTA were the highest for Pb(II) and Cd(II). The order of sorption for Amberlite IRA 458, Amberlite IRA 958 as well as Amberlite IRA 67 can be as follows: Pb(II) > Cd(II) > Zn(II) > Cu(II) > Ni(II) > Co(II). The stability of forming complexes was also compared. The estimation of the capacities of anion exchangers under investigation by the continuous column studies was also carried out. 相似文献
The objective of the Danish pesticide monitoring programme for fruit and vegetables was to check for compliance with the maximum residue levels in foods and to monitor the residue levels to assess the pesticide exposure of the Danish population. Sampling plans were designed based on previous findings and on food consumption data. Approximately 60% of the samples were selected on the basis of positive findings in samples from the previous 5 years. The remaining samples reflected the pattern of food consumption in Denmark. In addition, a rolling programme is maintained for commodities with a low consumption and no detected residues. Within each commodity, the sampling was random. Samples (n = 4150) of mainly fresh, conventionally grown fruit and vegetables were taken throughout the chain of suppliers including foodprocessing companies. Of the samples, 3% were frozen products and 2% were organically grown. Of the samples, 35% were of Danish origin, with 65% originating from other countries. Three accredited laboratories performed analyses of the samples using capillary gas chromatography, liquid chromatography and spectrophotometric methods. Results were registered online into a central database. Residues were found in 54% of the samples of fruit but only in 13% of the vegetables. Residues above the MRL were found in 4% of all samples of fruit and in 1% of vegetables. 相似文献
An important improvement of the photocatalytic activity of sol–gel prepared TiO2 has been achieved by sulphate pre-treatment, calcination at high temperature and further platinisation of the samples.
The presence of sulphuric acid clearly stabilised TiO2 surface area against sintering, maintaining at the same time anatase phase until higher calcination temperatures than in non-sulphated samples. Platinisation of the samples with different nominal amounts of platinum (from 0.5 to 2.5 wt%) was performed and the influence of sulphate treatment on the dispersion and deposit size of platinum on the TiO2 surface was studied.
Characterisation results and photocatalytic activity of these catalysts were compared with those of unmodified TiO2. Simultaneously sulphated and platinised TiO2 samples were highly active for phenol degradation, used as model reaction for the photocatalytic studies, having higher activities than only platinised or only sulphated samples. The activity of these samples were several orders of magnitude higher than that of the commercial TiO2 Degussa P25 (platinised or unmodified) as well, with independence of the nominal amount of platinum of the samples.
A wide characterisation of the samples was performed and correlations between characterisation results and activity properties are reported. 相似文献
ARIES-RS is one of the major magnetic fusion energy reactor designs that uses a blanket having vanadium alloy structure cooled
by lithium [1, 2]. It is a deuterium–tritium (DT) fusion driven reactor, having a fusion power of 2170 MW [1, 2]. This study presents the neutronic analysis of the ARIES-RS fusion reactor using heavy metal molten salts in which Li2BeF4 as the main constituent was mixed with increased mole fractions of heavy metal salt (ThF4 or UF4) starting by 2 mol.% up to 12 mol.%. Neutron transport calculations were carried out with the help of the SCALE 4.3 system
by solving the Boltzmann transport equation with the XSDRNPM code in 238 neutron groups and a S8–P3 approximation. According to the numerical results, tritium self-sufficiency was attained for the coolants, Flibe with 2%
UF4 or ThF4 and 4% UF4. In addition, higher energy multiplication values were found for the salt with UF4 compared to that with ThF4. Furthermore, significant amount of high quality nuclear fuel was produced to be used in external reactors. 相似文献
Magnetic properties and crystal structure of the hydrides of ferromagnetic compounds HoFe11−xCoxTi (x = 1, 2, 4, 6, 7, 11) are investigated. The crystal structure was determined by X-ray diffraction (XRD) analysis and the magnetization was measured in applied magnetic fields up to 10 T and at temperatures ranging from 5 K to room temperature. Results show that the crystal structure of the hydrides is the same as for parent compounds but with a moderate unit cell increase. Other properties such as saturation magnetization are affected by H insertion within the lattice. The effect of hydrogenation on magnetic anisotropy energy leads to disappearance of the FOMPs observed in the parent compounds. 相似文献