Die Frage der Verunreinigung des Bodensees durch Kohlenwasserstoffe gab in den letzten 15 Jahren Anlaß zu wachsender Besorgnis. Das Auftreten dieser Substanzklasse in Gewässern kann sowohl auf anthropogene Einträge als auch auf biogene Quellen zurückgeführt werden. Die Herkunft der in den Bodensee- Sedimenten nachgewiesenen Kohlenwasserstoffe ist umstritten und war Gegenstand mehrerer wissenschaftlicher Veröffentlichungen [1-4]. Mit Hilfe von Sedimentuntersuchungen ist es möglich, den Grad der Belastung eines Gewässers mit derartigen Stoffen zu erfassen und durch gezielte laterale Untersuchungen unter Umständen die Herkunft eines Stoffes zu ermitteln. Die nachstehende Arbeit behandelt die Untersuchung der Kohlenwasserstoffe in Sedimenten des Bodensees auf der Basis der im DGMK-Bericht 150 [5] vorgegebenen Kriterien, mit deren Hilfe in vielen Fällen eine Unterscheidung zwischen biogenen und mineralölbürtigen Kohlenwasserstoffen möglich ist.

Conclusion:<br /> Based on the above-mentioned fundamental advantages, gums should be considered the ideal phases for capillary GLC. Therefore, we strongly recommend users to select a gum whenever it is not precluded because of critical polarity/selectivity requirements.<br /> On the other hand we emphasize the great need for a much wider choice of gum phases. We are convinced that developing new and especially, more polar, gum phases is one of the best services that can be rendered to our analytical field. It is our hope that this may be a challenge for some polymer scientists.

The dynamics of availability of sediment phosphorus to the overlying water depends on P concentration of interstitial water which in turn depends on the redox intensity and the affinity of the solid sediment phases for P. In lakes and coastal waters substantial fractions of P become irretrievably deposited into the sediments, but in lakes the seasonal sequence of P release to the water from the sediments—after spring and fall overturn, preceding periods of massive algal growth—and of P binding to the sediments—prevailing during the later parts of the stagnation period—tends to facilitate algal blooms in shallow waters. With increasing depth of the lake the net removal of P from the water by the sediments becomes preponderant and the quantity of P released from the sediments to the epilimnion becomes small relative to other fluxes.<br/> Diffusional transport of P through interstitial water has been determined experimentally for various sediments; these results are compared with observed transfer rates across the sediment water interface in lakes and coastal waters.<br/> There are essentially the following ways for P to be deposited: (1) Adsorption of P on clays; (2) burying of detrital P; (3) chemical precipitation of apatite; and (4) diagenetic replacement of calcite (e.g. skeletal carbonate) by substitution of carbonate by phosphate. Accumulation of P, regenerated from detritus as it occurs most extensively in shallow waters and under conditions of counter-current systems (estuaries), does not in itself lead to an increase in the relative apatite saturation because the regeneration of one P atom is accompanied by an increase in acidity caused by the formation of <I>ca.</I> 106 CO₂ molecules. In order to exceed the critical ion product, the excess of CO₂ must be lost or neutralized. Such conditions are encountered in areas of upwelling, where excess CO₂ is lost to the atmosphere and under reducing conditions where denitrification and SO₄^2- reduction consume hydrogen ions.<br>/ A simplified steady state model will be used to depict that the dynamics of P transformations—especially the rate of regeneration of P from phytoplankton, benthos, detritus, and sediments and the rate of supply of soluble P to the algae—are more important in determining productivity than is the concentration of P or the P-reserve.

With the population growth and relevant development, water has become increasingly scarce in a growing number of countries and regions in the world. As the largest water user, the agricultural sector is facing a challenge to produce more food with less water. Crop water productivity (CWP), which is defined as the ratio of crop yield to actual evapotranspiration, is of importance for understanding water-food relationships. However, traditional methods are not sufficient for estimating crop water productivity (CWP) on a global scale given large spatial and temporal variations across different geographical locations. A GIS-based EPIC model, GEPIC, is developed to simulate crop water productivity by considering different factors such as climate conditions, soil properties, land use, water and fertilizer management etc. In this paper, GEPlC is applied to simulate wheat CWP on a global scale at a grid resolution of 30 arc-minute on the land surface.

This PAMS project helped to improve the environmental sanitation services (ESS) in a low-income neighborhood of Vientiane. At the same time, it helped to field test and validate the Household-Centered Environmental Sanitation (HCES) approach co-developed by NCCR North-South researchers.