Quantitative polarographische Bestimmung des Acetaldehyds

The Science of Nature -     

Bodenschutzverordnung bringt einheitliche Werte für Bodenbelastungen

Ohne Zusammenfassung     

GVO-Pollenmonitoring zum Bt-Maisanbau im Bereich des NSG/FFH-Schutzgebietes Ruhlsdorfer Bruch

Aim and Background Precautionary regulations for the production of genetically modified crops (Gentechnik-Pflanzenerzeugungsverordnung, GenTPflEV 2008) provide isolation distances for the cultivation of genetically modified maize – Bt-maize – in the vicinity of conventional maize cultivation (150?m) as well as of organic maize cultivation (300?m). Nature reserves are not included. The aim of this study was to investigate whether maize pollen of surrounding fields were dispersed in the Flora-Fauna-Habitat (FFH) Ruhlsdorfer Bruch. In the vicinity of the nature reserve Bt-maize species MON 810 as well as conventional maize was grown. The survey should provide appropriate isolation distances for the cultivation of Bt-maize with regard to sustainable protection of non-target-organisms (NTO) in the Ruhlsdorfer Bruch. Materials and Methods The collection of maize pollen in the Ruhlsdorfer Bruch was carried out at three sampling sites in the FFH or rather in the immediate vicinity in July and August 2007 by means of twelve technical and three biological pollen samplers. The technical samplers Sigma-2/PMF enable point sampling. They are primarily influenced by wind and topography and provide information about the effective entry, the maize pollen flow and the maize pollen deposition at the location of the sampler. Honey bees roam over longer distances and are hence planar collectors. Thus, they also provide information about the plants blooming in a distinct area. Furthermore, the biological preferences during the collection are captured, whereas a technical sampler does not perform a species dependent selection. Hence, both the technical and the biological samplers complement one another in their scope of application. The pollen samples were identified microscopically, enumerated quantitatively, and the pollen-DNA was analysed by means of the PCR-method. Results All monitoring sites at the Ruhlsdorfer Bruch revealed maize pollen entries. The pollen deposition reached values of 1.75 million maize pollen/m² in the close-up range. The monitoring sites located 120?m within the protected area still featured 99,000 maize pollen/m². As shown by the statistical analysis, at a distance of 1,000?m still 28,000 maize pollen/m² must be expected. The results of the microscopic pollen analysis of the pollen pellets proved that the bees collect maize pollen at all three sites. Although maize pollen is not the main food source the high collection efficiency of the bees resulted in large amounts of introduced pollen. The biomolecular proof of pollen-DNA in the field samples was corroborated by analogue results for both the technical and biological pollen sampling by two independent laboratories. The results of these quality controlled analyses gave unambiguous evidence that under the cultivation conditions in 2007 an entry of Bt-maize pollen into the FFH Ruhlsdorfer Bruch was existent. Discussion The maize pollen deposition at the Ruhlsdorfer Bruch corresponds with additional supra-regional investigations which were conducted over several years with the same method. However, the pollen entries into the Ruhlsdorfer Bruch are above-average. Possible reasons are the size of the maize fields (>?10?ha), the geographical collocation between maize fields and protected area (lee location, through-shaped, thermal currents) as well as weather conditions and maize bloom during the sampling period July and August 2007. A distance of 1,000?m or more is necessary to avoid maize pollen deposition of more than 100,000/m² with a probability of 90?%. Conclusions The results of this investigation prove an entry of Bt-maize pollen into the FFH under the cultivation and weather conditions in summer 2007. According to the results of this and related studies and considering precautionary principle and the effect terms defined in the Federal Immission Protection Law, it becomes clear that reasonable isolation distances between Bt-maize fields and protected areas have to be introduced in order to minimise the entry of GM-maize pollen and to prevent adverse effects on protected NTOs. Recommendations Due to the fact that no toxicological investigations are available for the butterflies occurring in the FFH, highest protection standards should be implemented to avoid Bt-maize pollen entries into the Ruhlsdorfer Bruch. That implies that highest possible isolation distances for Bt-maize cultivation have to be considered, but at least a distance of 1,000?m is recommended. Following this a maize pollen deposition of more than 100,000 maize pollen/m² should be pevented with a certainty of 90?% as well as an exceeding exposure of foraging insects. Outlook By means of the pollen monitoring it becomes possible to survey empirically defined limits of pollen exposure. This should be performed in the nature reserve area at sites of expected maximum exposure, e.?g. at the boundaries of the FFH towards the maize fields and at exposed sites.     

Influence of ionic strength and pH on the limitation of latex microsphere deposition sites on iron-oxide coated sand by humic acid

This study, for the first time, investigates and quantifies the influence of slight changes in solution pH and ionic strength (IS) on colloidal microsphere deposition site coverage by Suwannee River Humic Acid (SRHA) in a column matrix packed with saturated iron-oxide coated sand.Triple pulse experimental (TPE) results show adsorbed SRHA enhances microsphere mobility more at higher pH and lower IS and covers more sites than at higher IS and lower pH. Random sequential adsorption (RSA) modelling of experimental data suggests 1 μg of adsorbed SRHA occupied 9.28 ± 0.03 × 10⁹ sites at pH7.6 and IS of 1.6 mMol but covered 2.75 ± 0.2 × 10⁹ sites at pH6.3 and IS of 20 mMol. Experimental responses are suspected to arise from molecular conformation changes whereby SRHA extends more at higher pH and lower ionic strength but is more compact at lower pH and higher IS. Results suggest effects of pH and IS on regulating SRHA conformation were additive.     

Seasonal lipid dynamics of the copepods <Emphasis Type="Italic">Pseudocalanus minutus</Emphasis> (Calanoida) and <Emphasis Type="Italic">Oithona similis</Emphasis> (Cyclopoida) in the Arctic Kongsfjorden (Svalbard)

Seasonal lipid dynamics of various developmental stages were investigated in Pseudocalanus minutus and Oithona similis. For P. minutus, the dominance of 16:1(n−7), 16:4(n−3) and 20:5(n−3) fatty acids indicated a diatom-based nutrition in spring, whereas 22:6(n−3), 16:0, 18:2(n−6) and 18:1(n−9) pointed to a flagellate-based diet during the rest of the year as well as omnivorous/carnivorous low-level feeding during winter. The shorter-chain fatty alcohols 14:0 and 16:0 prevailed, also reflecting biosynthetic processes typical of omnivores or carnivores. Altogether, the lipid signatures characterized P. minutus as an opportunistic feeder. In contrast, O. similis had consistently high amounts of the 18:1(n−9) fatty acid in all stages and during all seasons pointing to a generally omnivorous/carnivorous/detritivorous diet. Furthermore, the fatty alcohol 20:1(n−9) reached high percentages especially in adult females and males, and feeding on Calanus faecal pellets is suggested. Fatty alcohols, as wax ester moieties, revealed significant seasonal variations in O. similis and a seasonal trend towards wax ester accumulation in autumn in P. minutus. P. minutus utilized its lipid deposits for development in the copepodite stages III and IV and for gonad maturation in CV and females during the dark season. However, CVs and females depended on the spring phytoplankton bloom for final maturation processes and reproduction. O. similis fueled gonad maturation and egg production for reproduction in June by wax esters, whereas reproduction in August/September co-occurred with the accumulation of new depot lipids. Both species revealed significantly higher wax ester levels in deeper (>50 m) as compared to surface (0–50 m) dwelling individuals related to a descent prior to overwintering.