Chemische Reaktionen von chlorvinylarsinverbindungen (Lewisite)

2-Chlorovinylarsine dichloride (Lewisite I) and 2,2′-dichlorodivinylarsine chloride (Lewisite II) react by room temperature rapidly and quantitatively with dithiols in a substitution reaction. The derivatives were identified with mass spectrometry. They can be detected with GC/ECD. This reactions can be used for the gas chromatographic detection of Lewisites in water and soil samples.     

Determination of chemical warfare agents in soil and material samples

A gas Chromatographic method for the determination of phenylarsenic compounds (sternutators) and their metabolites in soil and material samples is described. The chemical warfare agents (CWA), but not their hydrolysis and oxidation products, can be detected with GC/ECD. After derivatization with thiols or dithiols, the sum of diphenylarsenic and phenylarsenic compounds can be determined with GC/ECD. The comparison of the analytical results with and without derivatization shows that the sternutators in the investigated samples are metabolized in part.     

Study of leachability and fractional alteration of arsenic and co-existing elements in stabilized contaminated sludge using a flow-through extraction system

This study investigates the stabilization of As in the contaminated sludge after treatment with MnO(2) or Ca(OH)(2), and the influence of the stabilizing materials on the leachability of the co-existing elements Pb and Zn. By exploiting a continuous-flow assembly facilitating a modified Wenzel's sequential extraction scheme (designed for the fractionation of arsenic), it is possible to ascertain the leachability, mobility and fractional alteration of these elements under stimulated natural (flow-through) leaching conditions. The fractionation data show that more than 80% of As, Pb and Zn in the untreated sludge are bound in the amorphous Fe oxides fraction and residual fraction. The addition of MnO(2) has only an insignificant effect on As fractional transformation, while Ca(OH)(2) caused an increase in As mobility. For Pb, the decrease in leachability was clearly visible. The extractable Pb was reduced by 18% and 40% in stabilized MnO(2) and Ca(OH)(2) sludge samples, respectively. Unlike that of Pb, the mobility of Zn was not affected by the additives used. Their fractional distribution patterns before and after the stabilization process remained the same. The ability to produce detailed leaching profiles for As and other elements (Pb, Zn, Ca, Mn and Fe) meant that elemental associations in individual fractions could be examined. From the MnO(2)-treated sludge, the coincidence of the As, Pb, Zn, Fe, and Mn peaks seems to indicate a close association of these elements in the Fe-oxides-bound fraction. Furthermore, the leaching profiles may be used as evidence of a strong affinity between these elements and added MnO(2).     

Potential Effects of Direct Transfer Payments on Farmland Habitat Diversity in a Marginal European Landscape

Farmland habitat diversity in marginal European landscapes changed significantly in the past decades. Further changes toward homogenization are expected, particularly in the course of European agricultural policy. Based on three alternative transfer payment schemes, we modeled spatially explicit potential effects on the farmland habitat diversity in a marginal European landscape. We defined (1) a scenario with direct transfer payments coupled to production, (2) a scenario with direct transfer payments decoupled from production, and (3) a scenario phasing out all direct transfer payments. We characterized habitat diversity with three indices: habitat richness, evenness, and rarity. The habitat pattern in 1995 served as reference for comparison. All scenarios predicted a general trend of homogenization of the farmland habitat pattern, yet to a differing extent. Transfer payments coupled to production (Scenario 1) favored the abandonment of agricultural production, particularly in low-productive areas and arable land use in more productive areas. Habitat richness and habitat evenness had intermediate values in this scenario. Decoupling transfer payments from production (Scenario 2) supported grassland as most profitable farming system. This led to a grassland-dominated landscape with low values of all habitat diversity indices. Phasing out transfer payments (Scenario 3) resulted in complete abandonment or afforestation of agricultural land and extremely low values in all habitat diversity indices. Scenario results indicate that transfer payments may prevent cessation of agricultural production, but may not counteract homogenization in marginal landscapes. Conserving high farmland habitat diversity in such landscapes may require support schemes, e.g., Pillar Two of EU Common Agricultural Policy.     

Berücksichtigung von Variabilit?t und Unsicherheit in quantitativen Risikoabsch?tzungen (QRA)

Anhand des Anwendungsbeispiels einer bewohnten Altlast wird eine probabilistische Expositionsabsch?tzung durchgeführt und es werden M?glichkeiten aufgezeigt, Variabilit?t und Unsicherheit in der Sch?tzung separat zu erfassen. Zur Charakterisierung der Variabilit?t personenspezifischer Variablen (z.B. K?rpergewicht) werden in das Expositionsmodell Wahrscheinlichkeitsverteilungen eingesetzt; die stoffspezifischen Expositionsparameter werden konstant gehalten. Zus?tzlich wird die Ungewi?heit einer ausgew?hlten Variablen (Bodeningestionsrate) modelliert. Der Vergleich mit denworst-case-Sch?tzungen zeigt, da? diese in den oberen Randbereichen bzw, au?erhalb der Bereiche der probabilistischen Sch?tzung liegen und somit sehr konservative, u.U. unrealistische Sch?tzungen liefern.     

Wirkungsschwellen für chemische Stoffe in Biosystemen Eine theoretische Betrachtung

Die aus der chemischen Umsetzung mit endogenen Molekülen resultierende biologische Wirkung von Fremdstoffen wird diskutiert, ausgehend von den Grunds?tzen der Thermodynamik und Kinetik. Dabei führt ein unter vereinfachenden Annahmen durchgeführter Vergleich der thermischen Energieverteilung von Molekülen mit typischen biochemischen Aktivierungsenergien zu dem Ergebnis, da? aus statistischen Gründen für jede mit stofflichen Umsetzungen zusammenh?ngende biologische Wirkung ein Schwellenwert existieren sollte.     

Veränderung von Biokonzentration und Wirkung vom PSM in Anwesenheit von Huminstoffen

Humic substances, in aqueous bodies primarily fulvic acids, may demonstrate an inhibitory as well as an activating influence on organisms. We present evidence with bacteria-containing algal cultures and with cultures of the nematodeCaenorhabditis elegans. Structural elements of the fulvic acids which may be responsible for such effects are not yet known. Furthermore, the presence of fulvic acids may lead to increases in bioconcentration of xenobiotics. Increase in the toxicity of xenobiotics in the presence of humic substances have also been described. We present studies applying lethal as well as sublethal toxicity endpoints.     

全球化学品管理战略:机遇和风险

由以往和化学品安全相关的国际活动发展而来的国际化学品管理战略(SAICM)得到了联合国环境署(UNEP)理事会的支持.全球化学品行业认为SAICM应该被作为实现世界可持续发展首脑会议议定目标的路线图.全球在化学品安全使用问题上的不断进步将要求生产者、销售者、使用者、政府和其他利益相关方在生产链各有关环节责任分担的基础上采取共同协调的行动.从这个意义上说,制定一个全球战略提供了通过建立新的伙伴关系来实现化学品安全的机会.但是,如果SAICM成为国家、地区和国际层面附加的更严格的调控手段的基础,则其可能达不到期望的影响.