Physical and sensory properties of dairy products from cows with various milk fatty acid compositions   总被引：3，自引：0，他引：3  

Chen S  Bobe G  Zimmerman S  Hammond EG  Luhman CM  Boylston TD  Freeman AE  Beitz DC 《Journal of agricultural and food chemistry》2004,52(11):3422-3428

Dairy products from milk of cows fed diets rich in polyunsaturated fatty acids have a more health-promoting fatty acid composition and are softer but often have oxidized flavors. Dairy products made from cow's milk that has more- or less-unsaturated fatty acid compositions were tested for differences in texture and flavor from those made from bulk-tank milk. The milk was manufactured into butter, vanilla ice cream, yogurt, Provolone cheese, and Cheddar cheese. The products were analyzed for fatty acid composition, physical properties, and flavor. Milk of cows with a more monounsaturated fatty acid composition yielded products with a more monounsaturated fatty acid composition that were softer and had a satisfactory flavor. Thus, selection of cows for milk fatty acid composition can be used to produce dairy products that are probably more healthful and have a softer texture.  相似文献   

Polyzyklische Aromatische Kohlenwasserstoffe (PAKs) in den Böden der Rieselfelder der Stadt Münster (Westfalen)     

Peter Felix-Henningsen  Artur Wilbers  Gerd Crßmann 《植物养料与土壤学杂志》1993,156(2):115-121

Polycyclic Aromatic Hydrocarbons (PAHs) in soils of the Münster (Westfalia) irrigation fields From 1901 to 1975 municipal sewage waters with a daily amount of finally about 40.000 m³ were seeped in the irrigation fields of the city of Münster (Westfalia). Soil samples of former seeped sites and non-seeped neighbour sites have been examined with regard to 6 polycyclic aromatic hydrocarbons (PAHs) of the German “drinking water regulation”. The irrigation caused an enrichment of PAH in the topsoils of the former irrigation basins up to an average concentration of 0,57 mg PAH/kg soil, while the topsoils outside of the irrigation fields show an average concentration of only 0,14 mg PAH/kg soil. Significant correlations between different soil properties, e.g. the organic matter content, and the concentration of PAHs are not evident. After termination the irrigation of sewage water, single irrigation bassins were filled with substratum, which is contaminated with scoriaceous materials. The average PAH concentration of such an area amounts to 7 mg PAH/kg topsoil. The PAH distribution in a soil profile shows a decreasing concentration by depth but a clear enrichment in oxidized gleyic horizons (Go) of different age. Probably the PAHs were leached under recent conditions by chemical bond to dissolved organic carbon (DOC) and finally adsorbed by Fe oxides. Since the end of irrigation Fluoranthene, the most mobile PAH compound, was leached down to 110 cm depth. A contamination of the superficial groundwater at such sites cannot be excluded.  相似文献   

Comment on "The spatial extent of 20th-century warmth in the context of the past 1200 years"     

Bürger G 《Science (New York, N.Y.)》2007,316(5833):1844; author reply 1844

Osborn and Briffa (Reports, 10 February 2006, p. 841) identified anomalous periods of warmth or cold in the Northern Hemisphere that were synchronous across 14 temperature-sensitive proxies. However, their finding that the spatial extent of 20th-century warming is exceptional ignores the effect of proxy screening on the corresponding significance levels. After appropriate correction, the significance of the 20th-century warming anomaly disappears.  相似文献   

Squeezed soil-pore solutes — A comparison to lysimeter samples and percolation experiments     

Hartmut heinrichs  Gerd B?ttcher  Hans-J. Brumsack  Markus Pohlmann 《Water, air, and soil pollution》1996,89(1-2):189-204

This paper presents data on the chemical composition of soil pore fluids that have been obtained by a high-pressure squeezing technique and lysimeter sampling. Cation-exchange capacity has been calculated from cations extracted by a simple percolation method. All pore water concentrations are greatly influenced by the pH in solution. Most pore water concentrations do not simply parallel the corresponding mineralogical and chemical composition of the solids. The depth of the acidification front, as determined by analysis of samples obtained by percolation, is much better reflected in the chemical composition of the squeezed soil pore fluids than in the lysimeter samples. Distinct gradients are seen in Al concentration. In the B-horizons, concentrations of Al are close to the solubility of gibbsite. The pore water concentration profiles of Si and K apparently indicate dissolution of K-silicates, in particular K-feldspar. Contrary to the squeezed pore solutions the sulphate maximum concentration in the soil profile is not recorded by lysimeter samples. Mineral saturation indices show that pore solutions by squeezing are close to the saturation concentrations for K-jarosite and K-alunite. Sulphur-rich phases from the soil are compatible with mixtures of alunite jarosite, zaherite, basaluminite, and hydrobasaluminite. In the upper soil horizons the liquid/solid ratios [calculated as: concentration in solution (µg/ml) * solution fraction in solids (ml/g)/concentration in solids (µg/g)] increase in the order Ph < OC ≈ Zn < Cd and range from 10^?6 to 10^?3, indicating that Ph is most strongly held and still accumulates in the organic top soil. In the underlying deeper mineral horizons the ratios for Pb, Zn, and Cd decrease by one order of magnitude.  相似文献   

Chemical fixation of ammonia to soil organic matter after application of urea     

Gerd Johansson 《Acta Agriculturae Scandinavica, Section B - Plant Soil Science》2013,63(2):73-78

Chemical fixation of NH₃ to soil organic matter was studied in two Swedish soils with different contents of organic matter: a clay soil with 2.3% C and an organic soil with 36.6% C. ¹⁵N‐labelled urea was applied at different rates to both sterilized and non‐sterilized soils. After 10 days, the soils were extracted and washed with K₂SO₄ and determined for total N and atom% ¹⁵N excess. Urea N was recovered as non‐extractable N in sterilized soil corresponding to 9.7% of supplied ^l5N‐labelled urea in the organic soil and 2.2% in the clay soil. Since no biological immobilization is thought to occur in the sterile soil, this non‐extractable N is suggested to be chemically fixed to soil organic matter. Owing to urea hydrolysis in the clay soil, pH increased from 6.3 to 9.3 and in the organic soil from 5.7 to 6.9 and 8.8, respectively, at the low and high urea supply.  相似文献   

Sulfate transport and release in technogenic soil substrates: experiments and numerical modeling     

Horst Schonsky  Andre Peters  Friederike Lang  Stefan Abel  Beate Mekiffer  Gerd Wessolek 《Journal of Soils and Sediments》2013,13(3):606-615

  相似文献   

From a stinking wastewater disposal field toward a recreation area—the story of an unconventional soil remediation in Berlin,Germany     

Gerd Wessolek  Björn Kluge  Steffen Trinks  Michael Facklam  Olaf Zeuschner 《Journal of Soils and Sediments》2018,18(2):481-493

  相似文献   

Organic carbon sequestration in earthworm burrows     

Axel Don  Bert Steinberg  Ingo Schöning  Karin Pritsch  Monika Joschko  Gerd Gleixner  Ernst-Detlef Schulze 《Soil biology & biochemistry》2008,40(7):1803-1812

Earthworms strongly affect soil organic carbon cycling. The aim of this study was to determine whether deep burrowing anecic earthworms enhance carbon storage in soils and decrease C turnover. Earthworm burrow linings were separated into thin cylindrical sections with different distances from the burrow wall to determine gradients from the burrow wall to the surrounding soil. Organic C, total N, radiocarbon (¹⁴C) concentration, stable isotope values (δ¹³C, δ¹⁵N) and extracellular enzyme activities were measured in these samples. Anecic earthworms increased C stocks by 270 and 310 g m^?2 accumulated in the vertical burrows. C-enrichment of the burrow linings was spatially highly variable within a distance of millimetres around the burrow walls. It was shown that C accumulation in burrows can be fast with C sequestration rates of about 22 g C m^?2 yr^?1 in the burrow linings, but accumulated C in the burrows may be mineralised fast with turnover times of only 3–5 years. Carbon stocks in earthworm burrows strongly depended on the earthworm activity which maintains continuous C input into the burrows. The enhanced extracellular enzyme activity of fresh casts was not persistent, but was 47% lower in inhabited burrows and 62% lower in abandoned burrows. Enzyme activities followed the C concentrations in the burrows and were not further suppressed due to earthworms. Radiocarbon concentrations and stable isotopes in the burrow linings showed an exponential gradient with the youngest and less degraded organic matter in the innermost part of the burrow wall. Carbon accumulation by anecic earthworm is restricted to distinct burrows with less influence to the surrounding soil. Contrary to the initial hypothesis, that organic C is stabilised due to earthworms, relaxation time experiments with nuclear magnetic resonance spectroscopy (NMR) did not reveal any enhanced adsorption of C on iron oxides with C stabilising effect. Our results suggest that earthworm activity does not substantially increase subsoil C stocks but burrows serve as fast ways for fresh C transport into deep soil horizons.  相似文献   

Storage and stability of organic matter and fossil carbon in a Luvisol and Phaeozem with continuous maize cropping: A synthesis   总被引：1，自引：0，他引：1  

Heiner Flessa  Wulf Amelung  Mirjam Helfrich  Guido L. B. Wiesenberg  Gerd Gleixner  Sonja Brodowski  Janet Rethemeyer  Christiane Kramer  Pieter M. Grootes 《植物养料与土壤学杂志》2008,171(1):36-51

Quantitative information about the amount and stability of organic carbon (OC) in different soil organic‐matter (OM) fractions and in specific organic compounds and compound‐classes is needed to improve our understanding of organic‐matter sequestration in soils. In the present paper, we summarize and integrate results performed on two different arable soils with continuous maize cropping (a) Stagnic Luvisol with maize cropping for 24 y, b) Luvic Phaeozem with maize cropping for 39 y) to identify (1) the storage of OC in different soil organic‐matter fractions, (2) the function of these fractions with respect to soil‐OC stabilization, (3) the importance and partitioning of fossil‐C deposits, and (4) the rates of soil‐OC stabilization as assessed by compound‐specific isotope analyses. The fractionation procedures included particle‐size fractionation, density fractionation, aggregate fractionation, acid hydrolysis, different oxidation procedures, isolation of extractable lipids and phospholipid fatty acids, pyrolysis, and the determination of black C. Stability of OC was determined by ¹³C and ¹⁴C analyses. The main inputs of OC were plant litter (both sites) and deposition of fossil C likely from coal combustion and lignite dust (only Phaeozem).  相似文献   

Exchangeable cations in rock fractions and fine earth in soil profiles of different genesis     

Gerd Deutschmann  Bernard Ludwig 《植物养料与土壤学杂志》2000,163(2):183-189

Data on accumulated exchangeable H, Al, Fe and Mn (M_a) cations in rock fractions in German soil profiles are scarce. The objective of this study was to describe the sum of accumulated M_a cations of fine earth and rock fragments in 11 deep soil profiles of varying genesis. Soil profiles were laid out at the sites Solling, Eifel, Harz mountains and the Erzgebirge and the parent materials included sandstones, siltstones, quartzite, slate, greywacke, diabase, gneiss and quartz porphyry. Exchangeable cations in the fine earth and rock fragments were measured in depths down to 6 m. Additionally, effective porosity and specific surface of rock fragments were determined. The effective porosity of the different rock fragments ranged from 4 to 28% (v/v), indicating that the rocks were accessible to solutions. For most samples, the cation exchange capacities (CEC) of the fine earth fractions were larger than those of the rock fragments, and the CEC (fine earth)/CEC (rock) ratios decreased with depth. All 11 profiles had small (<40%) amounts of exchangeable Na, K, Mg and Ca (M_b) cations in the fine earth fraction. Exchangeable M_a and M_b cations in the rock fragments changed similarly with depth as in the fine earth fractions for all profiles. Cumulative (rock + fine earth) M_a cations from 0—200 cm ranged from 474 to 1592 kmol_c ha⁻¹. The contribution of the rock fraction to the cumulative exchangeable M_a cations accounted for 13 to 85% of the total. The sum of exchangeable M_a cations was much higher than the cumulative acid deposition in western Germany since the beginning of industrialization, suggesting that carbonic acid and organic acids contributed largely to soil acidification. The rocks contribute significantly to buffering the acidity of the seepage water by silicate weathering and cation exchange. Therefore, acidification models which consider the fine earth fraction only, may lead to an overestimation of the rate of soil and groundwater acidification.  相似文献