Toxic Metals (As, Cd, Ni and Pb) and PM2.5 in Air Concentration of a Model Ceramic Cluster

The relationship between ambient concentrations of fine particulate matter and detrimental health effects remains a highly controversial issue. Increased incidence of mortality and morbidity due to cardiopulmonary complications has been associated with elevated levels of urban air particles with an aerodynamic of <2.5 ??m (PM2.5). The main aim of this paper was to present the assessment of the temporal and spatial variations of the PM2.5 fraction and its contents in arsenic, cadmium, nickel and lead in order to identify possible emission sources of these pollutants. Daily ambient aerosol samples (PM2.5) were taken in the province of Castellón from 2008 to 2009. Particle concentration levels were determined by gravimetry, and the As, Cd, Ni and Pb levels in the samples were determined by inductively coupled plasma mass spectroscopy. The season variation of these pollutants differs according to the emission source and the factors involved in dispersion. In the weekly trend, there were no significant differences in levels among sampling sites in relation to the day activity (working vs. non-working) due to chemical pollutants that are found in fine particulate fractions residing in the atmosphere longer than coarse particles, resulting in a more homogeneous concentration of pollutants over time. In order to identify similar behaviour between chemical pollutants and PM2.5, an assessment of the correlation between them was carried out. This behaviour study shows whether the source of contaminants is the same. A statistical analysis of the levels of PM2.5 and the presence of As, Cd, Ni and Pb in the different sampling sites was performed in order to evaluate the influence of the sampling point on the concentrations of these pollutants.     

Effectiveness of selection at CIMMYT's main maize breeding sites in Mexico for performance at sites in Africa and vice versa

The exchange of elite breeding materials across regions is an important way in which multinational maize breeding programmes access new genetic variation, improve efficiency and reduce costs. Our objectives were to examine whether CIMMYT's breeding programmes for tropical and subtropical environments in Mexico and Eastern and Southern Africa (ESA) can effectively share materials. Sets of selected and unselected lines were evaluated for per se and testcross performance in multiple environments in Mexico and ESA for grain yield, days to anthesis and plant height. Genotypic correlations between performance in Mexico and ESA as testcross and line per se were high (≥ 0.72) for all experiments, and indirect selection efficiency ranged from 67 to over 100% for all traits. Lines selected in ESA or Latin America performed equally well in each region, indicating selection was for broad rather than regional adaptation. Thus, breeding programmes of CIMMYT in both Mexico and ESA can benefit tremendously by exchanging breeding materials and test results, and elite selections from each region should be fast‐tracked for evaluation in the other.     

Agronomic Evaluation of Legume Cover Crops for Sustainable Agriculture

The agronomic characteristics of different legume cover crops and their effects on soil chemical properties were investigated in a short-term field study. We compared weed biomass, nitrogen equivalence, growth rate, leaf chlorophyll content, cover crop biomass, soil total organic carbon, and soil total nitrogen under eight different legume cover crops in a short-term field experiment. We found the highest growth rate, cover crop dry biomass, N plant content, and N contribution with C. ochroleuca plants, whereas for leaf chlorophyll content, soil organic carbon, and total nitrogen the highest values were found with M. pruriens. We did not find any significant difference among C. ochroleuca and M. pruriens for cover crop dry biomass. Our findings suggest that the incorporation of cover crops into the soil can change positively the soil chemical properties, such as soil organic carbon and total nitrogen. Our results also highlight the importance of considering the short-term effect of cover crops on the tropical soil fertility maintenance, in this case, Regosol.     

One- and two-dimensional direct chiral liquid chromatographic determination of mixtures of diclofop-Acid and diclofop-methyl herbicides

Simple one- and two-dimensional high-performance liquid chromatography (HPLC) methods for the simultaneous enantiomeric determination of alkyloxyphenoxypropionic acid herbicides is presented. Compounds studied were ( R, S)-2-[4-(2,4-dichlorophenoxy)phenoxy]propionic acid (diclofop-acid) and ( R, S)-2-[4-(2,4-dichlorophenoxy)]methyl propionate (diclofop-methyl). Mobile phases necessary to separate their enantiomers on an alpha1-acid glycoprotein chiral stationary phase are different; therefore, the simultaneous separation by an isocratic mode is not possible. The chiral separation method proposed involves a one-step gradient allowing for the simultaneous determination of both racemic enantiomers. Detection limits of the method were 0.03 mg/L for both diclofop-acid enantiomers and 0.14 and 0.15 mg/L for diclofop-methyl enantiomers, respectively. The two-dimensional method involves the use of two chromatographs in one achiral-chiral coupling. The LC-LC method is more suitable for complex samples because it involves an online cleanup effect. Detection limits were 1.25 and 1.87 mg/L for diclofop-acid and 2.70 and 3.02 mg/L for diclofop-methyl enantiomers, respectively. Accuracy, repeatability, and reproducibility have been studied in standard samples and a technical product.     

Increases in Growing Degree Days in the Alpine Desert of the San Luis Valley, Colorado

Most alpine ecosystem climate change studies identify changes in biota, several report abiotic factors and conditions, few report temperature changes, and few to none discuss growing degree days (GDD) changes. This study provides results of data analysis on changes in number of GDD in the alpine desert of the San Luis Valley (SLV) whose community is dominated by an irrigated agricultural region. Analysis indicates significant increases (p?<?0.05) in annual and growing season GDD₁₀, GDD_4.4 (potato), and GDD_5.5 (alfalfa) during 1994–2007 compared to 1958–1993. With one exception, all stations experienced significant increases in mean annual daily GDD between 0.12 and 0.50 day^?2 and growing season GDD day^?2 0.21 and 0.81. Higher temperatures increase numbers of GDD, quickening growth of crops and maturity at the cost of reduced yield and quality. Increases in GDD indicate the Valley’s agricultural region and economy may experience negative impacts as yields decrease and water use increases.     

Concurrent phenomena contributing to the formation of the aroma of wine during aging in oak wood: an analytical study

Red wine was stored in different oak barrels or in stainless steel, and samples were taken for two years to determine 79 aroma compounds. Aging in oak affects 41 compounds. The type of wood affects 11 compounds. At least seven different processes seem to take place concurrently in aroma evolution, and five such processes, affecting 37 compounds, are linked to the oak cask. These are extraction from the wood, oxidation of wine alcohols and amino acids, microbiological formation of ethyl phenols, sorption processes, and condensation of acetaldehyde with polyphenols. The wood can release linear gamma- and delta-lactones, beta-damascenone, and ionones. Some compounds are released very fast from wood, which suggests they lie in the external part of the wood. Some extraction profiles are too complex to be explained by physical processes. Finally, the levels of 2,5-dimethyl-4-hydroxy-3(2H)-furanone and 2-ethyl-5-methyl-4-hydroxy-3(2H)-furanone increase even in the reference wine, which suggests the presence of a precursor.     

Effect of salinity × calcium interaction on cation balance in melon plants grown under two regimes of orthophosphate

Melon (Cucumis melo L.) plants were grown hydroponically in a greenhouse to investigate the interaction of phosphorus (P) and calcium (Ca) under saline conditions on vegetative biomass and cation balance. Three levels of Ca (0.4, 2, and 8 mM) were combined factorially with two levels of phosphate (0.1 and 1 mM) under two regimes of NaCl salinity (10 and 80 mM). An increase of phosphate and salinity level decreased shoot and root growth. A strong antagonism between Ca and magnesium (Mg) was observed regardless of the salinity level. Calcium effect on growth depended on the salinity level. At low salinity, an increase of Ca reduced sodium (Na) concentration in all plant fractions. At high salinity, this effect was only significant in young and medium leaves. At low salinity and low Ca the reduction of growth could be due to Na toxicity and an unbalanced Ca/Mg ratio. In addition to that, at high salinity, the restoration of growth by increasing Ca concentration in the root medium could be due to an effect on water relation and by increasing potassium K/Na selectivity.     

Uptake,Transport, and Concentration of Chloride and Sodium in Three Citrus Rootstock Seedlings

ABSTRACT

Aspects of ammonium (NH₄ ⁺) toxicity in cucumber (Cucumis sativus L.) were investigated following growth with different N sources [nitrate (NO₃ ^?), NH₄ ⁺, or NH₄NO₃] supplied in concentrations of 1, 5, 10, or 15 mM. Plant dry weights and root: shoot ratios were lower with NH₄ ⁺-fed plants than with NO₃ ^?-fed plants. Ammonium accumulated strongly in leaves, stem, and roots when the concentration in the growth medium exceeded 1 mM. The increase in tissue NH₄ ⁺ coincided with saturation of glutamine synthetase activity and accumulation of glutamine and arginine. Low tissue levels of calcium and magnesium in the NH₄ ⁺-fed plants constituted part of the NH₄ ⁺-toxicity syndrome. Additions of small amounts of NH₄ ⁺ to NO₃ ^? -grown cucumber plants markedly increased the growth.     

Nitrate Reduction and Nutrient Accumulation in Wheat Grown in Soil Salinized with Four Different Salts

ABSTRACT

The effect of salinization of soil with Na₂SO₄, CaCl₂, MgCl₂, and NaCl (70:35:10:23) on the biochemical characteristics of three wheat (Triticum aestivum L.) cultivars (‘LU-26S,’ ‘Sarsabaz’ and ‘Pasban-90’) was investigated under natural environmental conditions. Twenty-day-old seedlings of all three cultivars were subjected to three salinity treatments: 1.3 (control), 5.0, and 10 dSm^?1 for the entire life period of plants. After 120 d of seed sowing, plant biomass production decreased by 49% and 65%, respectively, in response to 5 and 10 dSm^?1 salinity levels. Addition of salts to growth medium also had a significant adverse effect on plant height. Increasing salinity treatments caused a great reduction in nitrate reductase activity (NRA) of the leaf. The inhibitory effect of salinity on nitrate reduction rate was more pronounced at the reproductive stage than at the vegetative stage of plant growth. Wheat cultivars ‘LU-26S’ and ‘Sarsabaz’ showed less reduction in NRA due to salinity compared with ‘Pasban-90.’ Ascending salinity levels significantly reduced potassium (K⁺) and calcium (Ca²⁺) accumulation in shoots, while the concentration of sodium (Na⁺) was increased. Salts of growth medium increased the shoot nitrogen (N) concentration, whereas phosphorous (P) concentration of shoots was significantly reduced due to salinity. Wheat cultivars ‘LU-26S’ and ‘Sarsabaz’ proved to be the salt-tolerant ones, producing greater biomass, showing less reduction in NRA, maintaining low sodium (Na⁺), and accumulating more K⁺ and Ca²⁺ in response to salinity. These two cultivars also showed less reduction in shoot K⁺/Na⁺ and Ca⁺/Na⁺ ratios than in ‘Pasban-90,’ particularly at the 10 dSm^?1 salinity level.