Die Bedeutung von Lebensmitteln tierischer Herkunft für die Mykotoxinaufnahme beim Menschen

Mycotoxins are a heterogeneous group of secondary fungal metabolites. Their formation in food and feedstuffs is influenced by many factors, including humidity, temperature, pH, oxygen concentration, type of substrate or presence of competitive microflora. The Food and Agriculture Organisation of the United Nations estimated in 1985 that approximately 25% of the world’s grain supply is contaminated with mycotoxins. There are more than 300 known mycotoxins; however, due to their occurrence and concentrations in food, and their toxic potential, only few of these are relevant with regard to consumer protection. These include the aflatoxins, ochratoxins and trichothecenes like deoxynivalenol, zearalenone and fumonisins. In Germany, only aflatoxins in food and feedstuffs are subjected to legal regulations. Beside the negative effects of mycotoxins on health and performance of farm animals, it is of importance to consider to what extent mycotoxins might be carried over into edible tissues like meat, milk and eggs when fed to farm animals. The present review shows that the carry over of mycotoxins into edible tissues is relatively low and is dependent on the specific mycotoxin and animal species. For example, due to the microbial decomposition of mycotoxins in the rumen, the carry over of mycotoxins into edible tissues of ruminants is considerably lower compared to monogastric species (pigs, chickens). Furthermore, after a short withdrawal period of 4 to 14 days combined with the feeding of non-contaminated diets, most of the mycotoxins, aside from ochratoxin A, are no longer detectable in any edible tissue. Ochratoxin A has a high binding affinity to specific blood proteins and is reabsorbed in the kidney; these mechanisms delay its elimination and increase the withdrawal period to at least 4 weeks. However, aside from the concentration of these substances in food, the daily intake of contaminated food is important for the risk analysis of mycotoxins to humans. In a recent study, it has been shown that more than 50% of the daily intake of ochratoxin A is derived from cereals and cereal products, and 30% from red wine, coffee and beer. Mear products from pigs and chickens only account for 4% of the total intake, while products from ruminants are considered to be negligible. These results indicate that mycotoxin-contaminated edible tissue, as compared to plant products, only plays a minor role with respect to consumer protection.     

Shallow fluid flow over an obstacle: higher-order non-hydrostatic modeling and breaking waves

Environmental Fluid Mechanics - The simulation of shallow flows over obstacles is an important problem in environmental fluid dynamics, including exchange flows over seabed sills, atmospheric flows...     

Large Eddy Simulation of turbulence generated by a weak breaking tidal bore

A tidal bore is a natural and fragile phenomenon, which is of great importance for the ecology of an estuary. The bore development is closely linked with the tidal range and the river mouth shape, and its existence is sensitive to any small change in boundary conditions. Despite their ecological and cultural value, little is known on the flow field, turbulent mixing and sediment motion beneath tidal bores. Indeed, some striking features can be highlighted in two-dimensional simulations, such as large velocity fluctuations and flow recirculation structures. Using Large Eddy Simulation method, the numerical results emphasised the complicated turbulent structures and their unsteadiness under a tidal bore.     

Wildfire effects on soil nutrients and leaching in a tahoe basin watershed

A wildfire burned through a previously sampled research site, allowing pre- and post-burn measurements of the forest floor, soils, and soil leaching near Lake Tahoe, Nevada. Fire and post-fire erosion caused large and statistically significant (P < or = 0.05) losses of C, N, P, S, Ca, and Mg from the forest floor. There were no statistically significant effects on mineral soils aside from a decrease in total N in the surface (A11) horizon, an increase in pH in the A11 horizon, and increases in water-extractable SO4(2-) in the A11 and A12 horizons. Burning caused consistent but nonsignificant increases in exchangeable Ca2+ in most horizons, but no consistent or statistically significant effects on exchangeable K+ or Mg2+, or on Bray-, bicarbonate-, or water-extractable P concentrations. Before the burn, there were no significant differences in leaching, but during the first winter after the fire, soil solution concentrations of NH4+, NO3-, ortho-P, and (especially) SO4(2-) were elevated in the burned area, and resin lysimeters showed significant increases in the leaching of NH4+ and mineral N. The leaching losses of mineral N were much smaller than the losses from the forest floor and A11 horizons, however. We conclude that the major short-term effects of wildfire were on leaching whereas the major long-term effect was the loss of N from the forest floor and soil during the fire.     

Transient secondary currents behind a compression wave in an irregular channel

Environmental Fluid Mechanics - A compression wave is an unsteady rapidly-varied open channel flow motion, characterised by an increase in water depth. A detailed investigation was conducted in a...     

A Device for Measuring Volatile Organic-Carbon Emissions from Cooling-Tower Water

A manual method for measuring reduced sulfur compounds in kraft pulp mill and sulfur recovery plant emissions was evaluated. The method involves removing SO₂ from the gas stream (if present) with a citric acid-potassium citrate buffer that passes reduced sulfur compounds; thermal oxidation of all reduced sulfur compounds to SO₂; collection of the SO₂ in H₂O₂; and a titrimetric analysis of the H₂O₂ for SO₄ ^2?. A heated filter removes alkaline particulate matter that would produce a negative interference if absorbed by the buffer. When used at kraft pulp mills, the method agrees closely with Reference Method 16, provided that nonregulated reduced sulfur compounds, such as carbonyl sulfide, are not present in the emissions. At sulfur recovery plants, nonregulated reduced sulfur compounds, such as thiophene, are likely to be present in the emissions and will produce a positive bias in the results obtained with this method. The precision of the method ranges from 1 to 7 percent relative standard deviation.