On the Isotopic Composition of Pb in Cloud Waters in Central Germany. A Source Discrimination Study

Fifty seven (57) cloud water samples collected in 1 hr intervals during 9cloud events in 1997 at the summit of the Brocken (altitude 1142 m) in Central Germany were analyzed for their Pb concentrations and isotopic compositions. For comparison, filterdusts of such possible emitters as power plants, cement factories, waste incinerators, cars and others were also studied.Profiles over many hours reveal changes in composition correlatedwith changes in the origin of the air masses. Five main groups ofpossible sources of the Pb can be distinguished: most importantare (1) the European standard pollution ESP dominating the continent from Germany over France to Scandinavia and (2) industrial Pb (and soot from car exhausts) followed by (3) urban waste incinerators as well as (4) perhaps ores from Norilsk/Siberia, and, somewhat uncertain, (5) ores from PaleozoicEuropean deposits. Local and daily varying anthropogenic emissions of the sources (2–5) cause scatter of the points around the ESP correlation line. In soils all these variationsand individual signatures are levelled out so that specific sources of pollution cannot be identified anymore. Geogenic Pbfrom rocks and soils is the same as that from power plants and cement factories. It is one of the two nominal end components making up the mixture of the ESP. The less radiogenic end component of this mix which must contain Pb from very old deposits is somewhat elusive: none of the large Archaic or Proterozoic deposits could be identified. Most probably numerous sources contribute to this Pb. Pb from leaded gasoline seems to be absent or is hidden under the five components dominating the composition of the Pb in the European environment. This probably reflects phasing out of such gasoline in most European countries. The Pb in the clouds may contain a small component of old Proterozoic or even Archaic Pb, but it can also be modelled with Paleozoic Pb.     

The Isotopic Composition of Anthropogenic Pb in Soil Profiles of Northern Germany: Evidence for Pollutant Pb from a Continent-wide Mixing System

Seventy-five samples of six soil profiles from forests on different substrates plus one next to a motorway were analyzed for the variation of Pb concentration and isotopic composition with depth. A substantial fraction of the anthropogenic Pb (peak concentrations between 74 and 300 ppm) is still stored in the organic top soil, and seldom penetrates deeper than 20–30 cm. In (²⁰⁸Pb/²⁰⁶Pb) vs. (²⁰⁷Pb/²⁰⁶Pb)-diagrams the Pb in the uppermost layers of the profiles plots on an excellent correlation line (R = 0.99) indicating essentially a two-component mixing system. Values for the dust on Scottish plants, Norwegian and Swiss bogs as well as for aerosols collected over the North Atlantic (data from the literature) plot on the same correlation line showing that the Pb was deposited from a continent-wide mixing system with two apparent end members: The radiogenic one is similar to geogenic Pb and could consist of contributions from certain European ore deposits and from different soil components (e.g. silicates and Fe-oxides), power plants and cement factories. The less radiogenic component must contain or consist of Pb from Proterozoic or even Archaic ore deposits. However, the sources of this Pb remain somewhat elusive. In any case, this isotopic pattern is so consistent all over Europe that the correlation line may serve as a line of reference for quasi normal or European Standard Lead Pollution (ESLP). The gasoline derived Pb in the soils is swamped by Pb of other provenances.     

3-Hydroxy-4,5-dimethyl-2(5H)-furanone (Sotolon) causing an off-flavor: elucidation of its formation pathways during storage of citrus soft drinks.

Gas chromatography/olfactometry (GCO) and gas chromatography-mass spectrometry (HRGC-MS) revealed 3-hydroxy-4, 5-dimethyl-2(5H)-furanone (sotolon) to be responsible for the "burnt" and "spicy" off-flavor observed in citrus soft drinks during storage. Among the ingredients of citrus soft drinks, ethanol and ascorbic acid were identified as the essential precursors of sotolon. Two formation pathways were postulated by studies using (2)H (D)- and (13)C-labeled ethanol and ascorbic acid; i.e., sotolon is formed from two molecules of ethanol and carbons 2 and 3 of ascorbic acid (pathway 1), or it is generated from one molecule of ethanol and carbons 3-6 of ascorbic acid (pathway 2).     

Degradation of tetrahydro-beta-carbolines in the presence of nitrite: HPLC-MS analysis of the reaction products.

Motivated by the identification of numerous novel tetrahydro-beta-carboline-carboxylic acids in food samples, we studied the reactions of tetrahydro-beta-carbolines in the presence of nitrosating agents. The anticipated formation of nitroso derivatives from unsubstituted tetrahydro-beta-carbolines, and from tetrahydro-beta-carboline-3-carboxylic acids was indicated by HPLC-MS/MS analysis and validated by the characteristic product ion spectra of the respective nitroso compounds. In addition, oxidative decarboxylation resulted in formation of the corresponding dihydro-beta-carbolines, and in the generation of the beta-carbolines harman or norharman. Subsequently, we studied the reactivity of tetrahydro-beta-carboline-1-carboxylic acids derived from the Pictet-Spengler condensation of indole amines with alpha-oxo acids. Again, in the presence of nitrosating agents the rapid disappearance of the starting material was obvious, but no nitroso derivatives could be observed. Instead, further HPLC-MS/MS studies demonstrated that dihydro-beta-carbolines were the major products of tetrahydro-beta-carboline-1-carboxylic acids. Finally, we demonstrated that freshly isolated nitroso-precursors spontaneously decomposed to yield harman alkaloids. In conclusion, we revealed that nitroso-tetrahydro-beta-carbolines can represent intermediates involved in the generation of beta-carbolines, and we established a novel pathway for the formation of harman alkaloids from nutritional tetrahydro-beta-carbolines.     

Modellierung des Umwelt-Risikopotenzials von Pflanzenschutzstrategien im Zuckerrübenanbau

In frame of an cooperative research project the model SYNOPS to assess environmental risk of plant protection measurements has been successfully applied for evaluation of three chemical plant protection strategies in sugar beet growing tested in field experiments at 9 respectively 10 sites in 2008 and 2009. The assessment has shown relative advantages of the ??Minimal dosage strategy?? with a high number of pesticides against a ??Common practice strategy?? with a smaller number of pesticides and common dose rates and a ??Registered strategy?? with very few pesticides applied with the registered application dose. But all calculated risk indices for earthworms are below the neglect-limit where negative effect can be excluded with high confidence. The same has been found out for water organisms if the pesticide specific application requirements regarding buffer zones are complied with. The results of the field investigations regarding effects on earthworms have confirmed the results of model SYNOPS. Simulation of the tested strategies on all sugar beet fields in 5 large regions in Germany and the comparison with strategies in practice of these regions by means GIS-technology has shown their environmental soundness in general. Only very few calculated risk indices for algae were above the neglect-limit caused by extremely unfavourable application conditions. Whether there is a real risk should be investigated in further hot-spot analysis.     

Mapping potential exposure to drift of plant protection products*

A proposal for a practical, site‐specific approach for farmers has been developed to fulfil the drift restrictions and directions imposed on a registered plant protection product. The approach is based on exposure potential maps, primarily taking account of regional and local application conditions that reduce non‐target exposure. Firstly, the maps are focused on the spray drift exposure pathway. Using geographically referenced data, we have developed four exposure indicators that allow classification of potential non‐target exposure on the basis of local application conditions. This enables us to manage product application restrictions on a field‐to‐field basis by means of the exposure class to which each field is assigned. This easy‐to‐understand information can be distributed as paper maps or as digital maps to the farmer. The farmer himself no longer needs to assess whether local conditions reduce non‐target exposure. All calculations are carried out using very detailed topographic data which suit scales from 1:10 000 to 1:25 000. Processing and analysis of the GeoData is realized through GIS technology.     

Determination of 12 type A and B trichothecenes in cereals by liquid chromatography-electrospray ionization tandem mass spectrometry

A new sensitive method for the simultaneous determination of 12 trichothecenes (deoxynivalenol, nivalenol, 3-acetyldeoxynivalenol, 15-acetyldeoxynivalenol, fusarenon X, T-2 toxin, HT-2 toxin, neosolaniol, monoacetoxyscirpenol, diacetoxyscirpenol, T-2 triol, and T-2 tetraol) by liquid chromatography-electrospray ionization tandem mass spectrometry (LC-ESI-MS/MS) is presented. The development of the method and investigations on the matrix influence on the MS signal are described in particular. The matrix effect was thereby minimized by using an internal standard, a special mobile phase, and specific fragmentation parameters. The sample was extracted with acetonitrile/water (84:16, v/v), and the extract was cleaned up with a MycoSep 227 column. Quantification was based on the internal standard de-epoxy-deoxynivalenol. Calibration curves were linear between 16 and 1600 ng/g, and the limits of detection ranged from 0.18 to 5.0 ng/g. The developed method was applied for the determination of trichothecenes in 120 naturally contaminated wheat and oat samples.