Chemical- and effect-oriented exposomics: Three Gorges Reservoir (TGR)

Exposomic studies of the rapidly changing environment of the Three Gorges Reservoir (TGR) after its impounding is elaborated as a novel field of human and environmental research. Molecular exposomics is focused on the measure of all exposures to molecules and especially persistent organic pollutants-like compounds are of emerging interest due to their lifetime existence in the environment and humans. Theoretical considerations in general and particular for the TGR are deduced and presented using quantitative approaches for this research field. Since exposomics is strongly time-dependent, a theory is presented to link extension of exposure, time, and related effects. Similarity to the first law of thermodynamics is outlined. On top of this, the integrated use of biomarkers is presented employing chemical analysis for biomarkers of exposure and effects, biomarkers in vivo, in vitro approaches and the link between chemical mixtures, and the onset of disease and lethality. Besides real organisms, also virtual organisms are favored to act as well-defined sub-compartments such as fat of biota and with respect to time of exposure. Exposomics is the perspective of risk evaluation and chronic exposures in the running century. It needs novel theories, approaches, and integrated action between medical and environmental disciplines. The existing knowledge about molecular stressors has to be assembled and put into a context especially with respect not only to time resp. lifetime exposure of humans but also eco-toxicological findings by using highly conserved phylogenetic mechanisms to enable links between human and risks of environmental biota. The TGR is a good example not only to employ biomonitoring of real but also virtual organisms due to the lack of established ecotopes in this changing environment so far. Progress in understanding long-term risks requires a proper theory as well as novel tools such as virtual organisms. On top, multidisciplinary approaches and the utilization of existing knowledge about the exposure of the environment and humans have to be merged and directed into mutual concepts. Effect-oriented and chemical analysis must be designed time-oriented to determine lifetime exposures of mankind and nature. Perspectively, a first attempt about exposomic theory and concepts is proposed and has to be developed experimentally further enclosing virtual besides of real organisms and compartments. Environmental and human exposomics have to be considered as a unified global issue in order to effectively utilize their mutual existing knowledge most effectively. The TGR is a challenging model system aiming this objective.     

Vivianite precipitation and phosphate sorption following iron reduction in anoxic soils

Phosphorus retention in lowland soils depends on redox conditions. The aim of this study was to evaluate how the Fe(III) reduction degree affects phosphate adsorption and precipitation. Two similarly P-saturated, ferric Fe-rich lowland soils, a sandy and a peat soil, were incubated under anaerobic conditions. M?ssbauer spectroscopy demonstrated that Fe(III) in the sandy soil was present as goethite and phyllosilicates, whereas Fe(III) in the peat soil was mainly present as polynuclear, Fe-humic complexes. Following anoxic incubation, extensive formation of Fe(II) in the solids occurred. After 100 d, the Fe(II) production reached its maximum and 34% of the citrate-bicarbonate-dithionite extractable Fe (Fe(CBD)) was reduced to Fe(II) in the sandy soil. The peat soil showed a much faster reduction of Fe(III) and the maximum reduction of 89% of Fe(CBD) was reached after 200 d. Neoformation of a metavivianite/vivianite phase under anoxic conditions was identified by X-ray diffraction in the peat. The sandy soil exhibited small changes in the point of zero net sorption (EPC?) and P(i) desorption with increasing Fe(III) reduction, whereas in the peat soil P desorption increased from 80 to 3100 μmol kg?1 and EPC? increased from 1.7 to 83 μM, after 322 d of anoxic incubation. The fast Fe(III) reduction made the peat soils particularly vulnerable to changes in redox conditions. However, the precipitation of vivianite/metavivianite minerals may control soluble P(i) concentrations to between 2 and 3 μM in the long term if the soil is not disturbed.     

Clonal Re-Introduction of Endangered Plant Species: The Case of German False Tamarisk in Pre-Alpine Rivers

The scope of re-introduction as a measure for plant species protection is increasing, but as long as no standardized methods are available, species-specific assessments are necessary to determine whether seeds, adult plants or plant fragments should be used. The endangered German False Tamarisk (Myricaria germanica), which occurs on gravel bars along pre-alpine rivers, is difficult to grow from seeds. Thus, propagation of stem cuttings was investigated as an alternative method. Experiments were conducted in a greenhouse and a field site with three treatments: cutting length 5 or 10 cm, vertical burial 5 or 10 cm, and water level low or high. Plants grown in the greenhouse were transplanted to the River Isar to test establishment of rooted cuttings on gravel bars. The cuttings in the greenhouse showed high survival (34-96 %). Survival and biomass production were greatest for 10-cm cuttings buried at 10-cm depth, while only one of the 5-cm cuttings survived at this depth, and no significant effect of variation in water level was observed. None of the cuttings transplanted to field sites survived, most likely because of drought stress and competition. We conclude that for re-introduction of Myricaria germanica rooted cuttings can be easily produced in large quantities, while transplantation to near-natural environments has to be improved to reduce mortality.     

REGIONAL DETECTION OF CHANGE IN WATER QUALITY VARIABLES1

ABSTRACT: The detection of change in a hydrologic varaible, particularly water quality, is a current problem. A method is presented for testing whether there has been a shift in the mean of a hydrologic variable based on the well established bivariate normal distribution theory. In this technique, the dependent, or target, and the independent, or control, variables are formed as weighted linear combinations of the mean values at a number of locations in a selected target and control area. The weighting factors are determined based on a mathematical programming technique which minimizes the conditional coefficient of variation thereby minimizing the number of observations required to detect a change of a preselected magnitude in the mean of the target area. The result is a situation where a savings in the number of observations required to detect a change is a consequence of adding more stations: the space-time tradeoff. Two applications of the technique are presented, the first using electrical conductivity (EC) data from two sets of river basins and the second using EC data from a set of basins as the target variable and annual discharge as the control. The results indicate that a significant savings in time can be achieved by using this method.