耕作方式对Brookston粘壤土团聚体中有机碳分布及矿化的影响

以加拿大安大略省西南部的Brookston粘壤土为研究对象,测定免耕(NT)、秋翻(MP)和牧草连作(BG)管理下特定团聚体(0.25～0.5 mm,1～2 mm)中土壤有机碳(SOC)的分布与动态变化.探索耕作方式对团聚体中SOC数量与稳定性的影响.结果表明:与MP和NT土壤相比,BG土壤团聚体SOC含量较高,且较为活跃;与MP相比,NT方式下团聚体的SOC含量较高,且随着团聚体粒径增大SOC含量增加; NT方式下团聚体中的SOC更加活跃;两种团聚体中SOC的稳定性随耕作方式变化而不同,长期NT下没有显著差别,长期MP下1～2mm团聚体较0.25～0.5 mm团聚体稳定.     

Occurrence and Distribution of Perfluorooctane Sulfonate and Perfluorooctanoic Acid in the Rivers of Tokyo

Comprehensive survey of major rivers in the Tokyo metropolitan area was conducted for clarifying the emission sources of perfluorooctane sulfonate (PFOS) in Tokyo. PFOS was found at all sampling sites at concentrations ranging from 0.5 to 58 ng L^?1; in addition to this, it was also indicated that unknown PFOS emission sources are present in the midstream of the Tama River basin. The relationship between PFOS and perfluorooctanoic acid (PFOA) was constant at a ratio of 10:3 (PFOS/PFOA) throughout the Tama River basin. The sum of daily load amounts of PFOS from Tokyo’s major rivers to Tokyo Bay reached 215 g day^?1. This value corresponds to 12.8 μg day^?1 per person using the sum of wastewater treatment district populations. In contrast, an estimation of PFOS contribution of domestic wastewater was also attempted, and the contribution was 1.6 μg day^?1 per person. We took samples up trunk sewers in the Tama River and finally found at the highest PFOS concentration (58,000 ng L^?1) from one of the wastewater of the electronic parts manufacturing facilities.     

A method for the analysis of the δ18O of inorganic phosphate extracted from soils with HCl

The oxygen isotope composition of phosphate (δ¹⁸O‐PO₄) has successfully been used to study the biological cycling of phosphorus (P) in seawater and marine sediments. However, only a few studies have used this approach in soils. In order to analyse δ¹⁸O‐PO₄, phosphate must be extracted from the soil, purified and converted to silver phosphate (Ag₃PO₄). The published extraction methods, successfully applied to marine waters and sediments, lead to the precipitation of impure Ag₃PO₄when used with soils or organic‐rich samples. Here we present an improved purification protocol, designed for soils and other organic‐rich samples. After extraction with HCl, phosphate is purified with multiple mineral precipitations that do not require extreme pH adjustments of the solutions. We show that contaminant‐free Ag₃PO₄ can be produced from fertilizers and various soils with different chemical and physical characteristics. Our first isotopic results confirm that differences in P status and availability in soils are expressed in the δ¹⁸O‐PO₄ signal, indicating the potential of this isotopic tracer to understand P dynamics in soil systems.     

A Multivariate Hidden Markov Model for the Identification of Sea Regimes from Incomplete Skewed and Circular Time Series

The identification of sea regimes from environmental multivariate times series is complicated by the mixed linear?Ccircular support of the data, by the occurrence of missing values, by the skewness of some variables, and by the temporal autocorrelation of the measurements. We address these issues simultaneously by a hidden Markov approach, and segment the data into pairs of toroidal and skew-elliptical clusters by means of the inferred sequence of latent states. Toroidal clusters are defined by a class of bivariate von Mises densities, while skew-elliptical clusters are defined by mixed linear models with positive random effects. The core of the classification procedure is an EM algorithm accounting for missing measurements, unknown cluster membership, and random effects as different sources of incomplete information. Moreover, standard simulation routines allow for the efficient computation of bootstrap standard errors. The proposed procedure is illustrated for a multivariate marine time series, and identifies a number of wintertime regimes in the Adriatic Sea.     

Chemical and physical changes in milk protein concentrate (MPC80) powder during storage

The solubility and chemical changes due to the Maillard reaction were investigated in milk protein concentrate powder containing 80% protein (MPC80) during storage at temperatures and relative humidities in the ranges of 25-40 °C and 44-84%, respectively. The Maillard reaction was studied by measuring furosine (a product of lactosylated protein after digestion with acid) and free hydroxymethylfurfural (HMF) contents by HPLC and L*, a*, b* values with a color-meter. Furosine, free HMF, and browning in MPC80 increased during storage, whereas the solubility decreased. The correlation between the Maillard reaction and solubility loss was explored in modified MPC80 to which glucose was added to enhance the rate of the Maillard reaction. More furosine and brown pigments were observed in the glucose-containing MPC80 than in MPC80 with added lactose. The opposite trend occurred for solubility, suggesting that the Maillard reaction may be a cause of solubility loss in MPC powder.     

Effect of germination temperatures on proteolysis of the gluten-free grains sorghum and millet during malting and mashing

Our study showed that sorghum and millet followed a similar pattern of changes when they were malted under similar conditions. When the malt from these cereals was mashed, both cereal types produced wide spectra of substrates (sugars and amino acids) that are required for yeast fermentation when malted at either lower or higher temperatures. At the germination temperatures of 20, 25, and 30 °C used in malting both cereal types, production of reducing sugars and that of free amino nitrogen (FAN) were similar. This is an important quality attribute for both cereals because it implies that variation in temperature during the malting of sorghum and millet, especially when malting temperature is difficult to control, and also reflecting temperature variations, experienced in different countries, will not have an adverse effect on the production and release of amino acids and sugars required by yeast during fermentation. Such consistency in the availability of yeast food (substrates) for metabolism during fermentation when sorghum and millet are malted at various temperatures is likely to reduce processing issues when their malts are used for brewing. Although sorghum has gained wide application in the brewing industry, and has been used extensively in brewing gluten-free beer on industrial scale, this is not the case with millet. The work described here provides novel information regarding the potential of millet for brewing. When both cereals were malted, the results obtained for millet in this study followed patterns similar to those of sorghum. This suggests that millet, in terms of sugars and amino acids, can play a role similar to that of sorghum in the brewing industry. This further suggests that millet, like sorghum, would be a good raw material for brewing gluten-free beer. Inclusion of millet as a brewing raw material will increase the availability of suitable materials (raw material sustainability) for use in the production of gluten-free beer, beverages, and other products. The availability of wider range of raw materials will not only help to reduce costs of beer production, but by extension, the benefit of reduced cost of production can be gained by consumers of gluten-free beer as the product would be cheaper and more widely available.     

Identification and quantification of cyclolinopeptides in five flaxseed cultivars

Cyclolinopeptides are a group of naturally occurring hydrophobic cyclic peptides found in flaxseed and flax oil that have immunosuppressive activity. This study describes the measurement of flaxseed cyclolinopeptide concentrations using an internal standard HPLC method. In addition, the concentration of cyclolinopeptides in the seed of Canadian flax cultivars grown at two locations over two years is reported. The data are consistent with the formation of flaxseed cyclolinopeptides from two ribosome-derived precursors. Each precursor protein includes the sequences corresponding to three cyclolinopeptides from which those cyclolinopeptides are presumably derived by precursor processing. The concentrations of cyclolinopeptides C and E, which are encoded by the same gene sequence, are highly correlated, and the concentrations of cyclolinopeptides D, F, and G, which are encoded by a second gene sequence, are also highly correlated. The strong correlation between the cyclolinopeptides arising from the same gene may prove to be important in understanding how peptide concentration is controlled. Additional research may lead to approaches to improve flax either as a platform for peptide production or as a source of oil with improved drying properties and flavor.     

Response of Rice Seedlings to Copper Toxicity and Acidity

Metal toxicity and soil acidity affect plant growth. A hydroponic experiment was conducted to simulate effects of pH and copper concentration [Cu] on early growth and biomass production of high-yielding rice seedlings (Oryza sativa L. cv. ‘NIAB 6’). The rice seedlings were allowed to grow in Yoshida nutrient solution with 1 (control), 8, 16, and 32 μM Cu at buffered pH levels of 4.5, 5.0, and 5.5, respectively. Shoot and root growth, leaf chlorophyll content, and root lipid peroxidation and K⁺ leakage of 15-day-old rice seedlings were determined. Results show that [Cu] had significant adverse effects on rice seedlings. Shoot height and root length were reduced by 18%–60% and 7%–69%, respectively, compared with the control, and shoot and root weight decreased by 26%–56%, and 25%, respectively, in response to progressive increases in [Cu]. Similarly, leaf chlorophyll content decreased by 150%–245% compared with the control treatment. Rice seedling roots suffered from significant increases in lipid peroxidation followed by K⁺ leakage (> 8–23 times) in response to increasing [Cu]. Averaged across [Cu], seedling growth and biomass were greater at pH 5.5 than at other pH treatments. In some instances, increasing pH minimized the adverse effects of Cu at low concentrations on rice seedlings.     

Global Bibliometric Analysis of the Research in Biochar

Global interest in studying biochar stems from its ability to sequester carbon in soil and render nutrients and moisture more readily available to root systems. Therefore, a bibliometric analysis was conducted to investigate global scientific publications related to biochar research, providing insight into the number of articles published, journal platforms, subjects, citations, and overall trends. The primary databases employed were the Web of Science and Science Citation Index. A total of 1,697 articles published between 2000 and 2015 were evaluated. This systematic bibliometric analysis will assist research groups and individuals to understand global biochar research trends and focus future research. The influence of biochar on soil, plants, and the environment continues to require greater attention.     

Effect of biofertilizers on the nutrient availability in soil in relation to growth,yield and yield attributes of Stevia rebaudiana

A field experiment was conducted at Rani Chandramma Agricultural University (Arabhavi, Belgaum), Karnataka, India, in basic soil to study the nutrient availability in soil, yield and yield attributes of the medicinal plant stevia (Stevia rebaudiana). The results showed that the availability of nutrients such as nitrogen (N), phosphorus (P) and potassium (K) in the soil increased up to the fifth month; and thereafter, decreased by the same amount with the progress of the plant growth up to the sixth month, irrespective of treatments. Results also showed that the fresh and dry biomass yields significantly increased up to the sixth month with different treatments, but the yield attributes like plant height and the number of branches were observed to be varied with various treatments, being highest in the combined application of biofertilizers over that of their corresponding sole applications.