Soils affected by acid mine waters in galicia (N.W. Spain)     

R. De Anta Rosa Calvo  Angel Perez Otero 《Water, air, and soil pollution》1994,73(1):247-263

Contaminated soils and surface waters, from copper mining in Galicia, are acidic, high in sulphate and increase appreciably in the concentration of elements such as Al, Fe, Ca, Mg, K, Mn, Cu and Zn by contact with soils and fragments of rock of an amphibolic composition. Application of activity data to mineral equilibrium diagrams illustrates the instability of Al-hydroxides and aluminosilicates compared to Al-sulphates of the alunite and jurbanite type, in the waters which are most acid and display sulphate activities close to 10^?2 M. The solution extracted from soils around the spoil heaps reflects the strong influence of the most heavily contaminated run-off waters, with little or no buffering by the solid phase. This aspect may be accounted for by both a brief time of residence and a real decrease of the acid buffering power of these soils, whose primary minerals undergo strong acidolysis. Neoformation of Al-sulphate (and Fe-sulphate) is observed both in soils and in the channels of the contaminated streams, above all the points of contact with non-acid or slightly acid waters.  相似文献   

免耕和秸秆还田对东北黑土区土壤团聚体组成及有机碳含量的影响   总被引：2，自引：5，他引：2  

闫雷  董天浩  喇乐鹏  刘鸣一  孙小贺  孟庆尧  张钰莹  张乃文  孟庆峰 《农业工程学报》2020,36(22):181-188

为解决东北黑土区因不合理耕作导致的土壤结构性状变差及有机碳含量下降的问题，该研究于2015年开始，在黑龙江省哈尔滨市东北农业大学向阳试验基地开展。设置免耕+秸秆还田（NTS）、免耕（NT）、翻耕+秸秆还田（CTS）、翻耕（CT）4种处理，于2018、2019年采集土样，研究免耕措施及秸秆还田对东北薄层黑土区0～10、>10～20 cm土壤团聚体稳定性、土壤有机碳含量、各粒径团聚体内有机碳含量影响。结果表明：2018和2019年0～10、>10～20 cm土层NTS处理>5 mm水稳性团聚体百分比含量及平均重量直径（MWD）显著高于其他3种处理，NTS及NT处理土壤有机碳含量显著高于CTS及CT处理（P?<0.05），4种处理各粒径水稳性团聚体有机碳含量峰值总体出现在1～2 mm处，NTS及NT处理>5、2～5、1～2 mm有机碳贡献率整体高于CTS及CT处理。研究表明，免耕与秸秆还田有利于薄层黑土坡耕地耕层土壤团聚体稳定性的提高和各粒级下团聚体有机碳的积累，与其他3种处理相比，免耕+秸秆还田效果更佳。  相似文献   

Soil CO₂ efflux following rotary tillage of a tropical soil     

N. La Scala  Jr.  A. Lopes  A.R. Panosso  F.T. Camara  G.T. Pereira 《Soil & Tillage Research》2005,84(2):222-225

Stopping the increase of atmospheric CO₂ level is an important task and information on how to implement adjustments on tillage practices could help lower soil CO₂ emissions would be helpful. We describe how rotary tiller use on a red latosol affected soil CO₂ efflux. The impact of changing blade rotation speed and rear shield position on soil CO₂ efflux was investigated. Significant differences among treatments were observed up to 10 days after tillage. Cumulative CO₂ efflux was as much as 40% greater when blade rotation of 216 rpm and a lowered rear shield was compared to blade rotation of 122 rpm and raised shield. This preliminary work suggests that adjusting rotary tiller settings could help reduce CO₂ efflux close to that of undisturbed soil, thereby helping to conserve soil carbon in tropical environments.  相似文献   

Determination of selenium content in different types of seed oils by cathodic stripping potentiometry (CSP)     

Dugo G  La Pera L  Pollicino D  Saitta M 《Journal of agricultural and food chemistry》2003,51(19):5598-5601

Seed oils are consumed worldwide; moreover, they are used in the alimentary, cosmetic, pharmaceutical, and chemical industries. Due to their diffusion, it is interesting to investigate the presence of important micronutrients such as selenium in seed oils. The aim of this work was to develop a rapid, precise, and sensitive cathodic stripping potentiometry (CSP) method to determine the concentration of selenium in different types of seed oils. Selenium was extracted from the oily matrix by concentrated hydrochloric acid treatment at 90 degrees C. The analysis was executed by applying an electrolysis potential of -150 mV for 60 s and a constant current of -30 microA. Under these conditions, detection limits of <0.5 ng g(-1) were obtained. The method reproducibility (expressed as total RSD %) spanned from 0.2 to 0.8%. Recoveries ranged from 92.1 to 97.5%, providing evidence that selenium quantification remained unaffected by the extraction procedure described. The results obtained with the proposed method were compared with those obtained via graphite furnace atomic absorption spectroscopy (GFAAS), a common method for determining selenium. The results of the two methods agreed within 93.5-107.7%. The mean amounts of selenium found were 313.0 +/- 2.0, 458.3 +/- 1.3, 224.6 +/- 0.9, 99.5 +/- 0.8, 332.2 +/- 0.5, 144.0 +/- 0.7, and 295.5 +/- 1.2 ng g(-1), respectively, in peanut, soybean, sunflower, rice, corn, grapestone, and seed oils.  相似文献   

Rheological properties of yoghurt made with milk submitted to manothermosonication     

Vercet A  Oria R  Marquina P  Crelier S  Lopez-Buesa P 《Journal of agricultural and food chemistry》2002,50(21):6165-6171

Manothermosonication (MTS) treatments, the simultaneous application of heat and ultrasound under moderate pressure, of milk during 12 s at 20 kHz ultrasound amplitude, 2 kg pressure, and 40 degrees C allowed elaboration of yoghurts with rheological properties superior to those of control yoghurts elaborated with untreated milk. Measurements performed on intact samples (compression tests, relaxation tests, and texture profile analysis) and on slowly stirred samples (flow curves, apparent viscosity, yield stress, and viscoelastic properties) showed that MTS yoghurts had stronger structures, which resulted in higher values of almost all of the many relevant rheological parameters. Homogenization of fat globules brought about by MTS treatments is not responsible for the superior properties of MTS yoghurts, because the control yoghurt was also elaborated with homogenized milk. These results show that MTS could be a useful tool to improve the texture of yoghurts.  相似文献   

Watering level effect on Thymus hyemalis Lange essential oil yield and composition     

Jordán MJ  Martínez RM  Cases MA  Sotomayor JA 《Journal of agricultural and food chemistry》2003,51(18):5420-5427

Thymus hyemalis Lange (chemotype thymol) was cultivated as an experimental crop under different watering level conditions in order to achieve 80, 60, 40, and 20% of the local potential evapotranspiration (Eto). Two harvesting periods were considered, winter and spring. As a consequence of the great variability among plants, essential oil yield percentages did not show statistically significant differences among seasons and different levels of water supply. Capillary GC-MS analysis of the essential oils permitted the detection of 84 volatile components. Among them, 54 are described for the first time as volatile constituents of the chromatographic profile of this Thymus species. Winter harvesting showed high concentrations in thymol percentage (25.92 +/- 4.39), the 40% Eto watering level being the best with respect to obtaining the optimum quality of this essential oil. However, in spring this thyme species needs a greater water supply (80% Eto) to achieve the same amount of thymol in the essential oil (29.20 +/- 2.83). From this, it was concluded that winter harvesting could be used for the extraction of the essential oil, with a low level of water supply, whereas spring harvesting could be employed for collection of leaves as a food condiment.  相似文献   

Immunochemical detection of formylated gamma(2)-casein in cheese     

Pizzano R  Nicolai MA  Siciliano R  Manzo C  Mazzeo MF  Addeo F 《Journal of agricultural and food chemistry》2004,52(4):649-654

An immunochemical approach has been developed to detect the use of formaldehyde as a bacteriostatic agent in dairy products. A synthetic peptide, reproducing the first five amino acid residues of the gamma(2)-casein sequence, was formylated to generate the novel haptenic structure, already well-recognized in formaldehyde-treated milk and arising out of molecular rearrangement after the addition of formaldehyde to the alpha-amino group of the histidine residue at the N terminus of gamma(2)-casein. A polyclonal antibodies preparation produced against the formylated peptide adduct proved to be a highly specific analytical tool for detecting the formylated adduct of gamma(2)-casein in formaldehyde-treated milk. Polyclonal antibodies obtained against the unmodified peptide were able to detect selectively residual native gamma(2)-casein in ripened cheese.  相似文献   

Structural carbohydrate differences and potential source of dietary fiber of onion (Allium cepa L.) tissues.     

Laura Jaime  Esperanza Mollá  Almudena Fernández  María A Martín-Cabrejas  Francisco J López-Andréu  Rosa M Esteban 《Journal of agricultural and food chemistry》2002,50(1):122-128

Onion tissues of three varieties were evaluated for dietary fiber (DF) composition. Insoluble (IDF) and soluble (SDF) dietary fibers were subjected to acid hydrolysis, and the resultant neutral sugars, uronic acids, and Klason lignin were quantified. Brown skin exhibited the highest total dietary fiber (TDF) content (65.8%) on a dry matter basis, followed by top (48.5%) and bottom (38.6%), IDF being the main fraction found. The SDF:IDF ratio decreased from inner to outer tissues. Brown skin and outer leaves byproducts appear to be the most suitable sources of DF that might be used in food product supplementation. The chemical composition reveals that cellulose and pectic polysaccharides were the main components of onion DF in all tissues, although differences between them were noticed. An increase in the uronic acids/neutral sugars ratio from inner to outer tissues was found, suggesting that the galactan side chain shows a DF solubilization role.  相似文献   

Relationships between agro/morphological characters and climatic parameters in Spanish landraces of lentil (Lens culinaris Medik.)   总被引：1，自引：0，他引：1  

Almudena Lázaro  Magdalena Ruiz  Lucía de la Rosa  Isaura Martín 《Genetic Resources and Crop Evolution》2001,48(3):239-249

  相似文献   

Is the application of carbendazim harmful to healthy plants? Evidence of weak phytotoxicity in tobacco.   总被引：1，自引：0，他引：1  

Pablo C García  Juan M Ruiz  Rosa M Rivero  Luis R López-Lefebre  E Sánchez  Luis Romero 《Journal of agricultural and food chemistry》2002,50(2):279-283

To understand the phytotoxic effects that certain bezimidazole fungicides exert on plant growth, the aim of the present study was to determine the effect of the fungicide carbendazim, on foliar biomass, pigment content, and nutrient levels in tobacco plants (Nicotiana tabacum L. cv. Tennessee 86). The fungicide applied was carbendazim with a purity of 100%, at three different rates: 1.3 mM (carb1), 2.6 mM (the recommended concentration, carb2), and 5.2 mM (carb3). The control treatment was without carbendazim. The application of dosages of this fungicide lower than recommended (1.3 mM) resulted, on the one hand, in greater dry weight and, on the other, higher carotenoid concentrations, as well as higher N and K concentrations with respect to control. On the contrary, the application of the carbendazim dosage higher than recommended (5.2 mM) caused a decrease in dry weight and in all of the foliar pigments, as well as all of the nutrients, with respect to the other dosages and control. These results appear to indicate that besides its direct antibiotic action against pathogens, the effects of this fungicide in plants could be dangerous, especially at higher dosages. Nevertheless, the negative effects of carbendazim can be avoided by reducing the amount applied in current agriculture.  相似文献