Veränderungen des NO/NO2-Verhältnisses in Nordrhein-Westfalen (1984–2004) und mögliche Ursachen

Objective and Background

The nitrogen oxides NO and NO₂ and, in particular, their ratio (NO/NO₂), play important roles in the radical-system of the atmospheric boundary layer. There were various indications upon a dropping NO/NO₂-ratio in citiex over the last years, however, no proof has been given yet Especially in densely populated areas such as the federal state of North Rhine-Westphalia (NRW), such a change can have significant influences upon various atmospheric reactions. The objective of this investigation was to prove the existence of a systematic change of the NO/NO₂-ratio, to describe the development of NO_x over the past 2 decades at different locations and to determine the causes for this development.

Methods

To detect changes of the NO/NO₂-ratio we processed the data of 11 continuously operating air quality stations of the State Environment Agency (LUA NRW) with time series reaching back up to 20 years. We investigated rural stations, stations in the urban background and heavily traffic influenced locations. It was possible to calculate and assess the NO/NO₂-ratio under consideration of the fast reaction of ozone with NO. There were clear indications towards existing trends and they could be determined as statistically significant using the nonparametric Mann-Kendall Test. The analysis of possible causes for the change of the NO/NO₂-ratio focused upon the change of the global radiation, the change of the patterns of the atmosphetic circulation, and the frequency of cyclones and anticyclones meteorological conditions in Central Europe, the introduction of automotive catalytic converters, and the development of the atmospheric oxidation-capacity.

Results and conclusions

The results are indicating a decline of the ratio at traffic-influenced stations with a statistical significance over 95%. The negative trend can also be detected at most urban background stations. It was problematic to perform the trend-analysis of the rural background station in the Egge-Mountains because of the fragmentary character of the dataset. Regional differences in the development of the NO/NO₂-ratio indicate towards various causes. Crucial for the situation at the rural areas are the changed trajectories of cyclones and anticyclones as well as the decline of the atmospheric oxidation-capacity, while the traffic plays another important role at urban stations. The negative trend at the traffic-stations was intensified by the introduction of catalytic converters, which lead to a reduction in emissions of NO_x

Recommendations and prospects

The significance of the NO/NO₂-ratio for the oxidation capacity of the atmosphere shows the necessity to further monitor this development. Previous investigations detected a decline in total NO_x without examining the relative development of the two nitrogen oxides towards each other. Gaining insight into the local differences of this ratio helps to allocate sources and to develop understanding of the atmospheric processes.     

The assessment of the energetic compound 2,4,6,8,10,12-hexanitro-2,4,6,8,10,12-Hexaazaisowurtzitane (CL-20) degradability in soil

CL-20 is a relatively new energetic compound with applications in explosive and propellant formulations. Currently, information about the fate of CL-20 in ecological systems is scarce. The aim of this study is to evaluate the biodegradability of CL-20 in soil environments. Four soils were used where initial CL-20 concentrations (above water solubility) ranged from 125 to 1500 mg of CL-20 per kg dry soil (corresponding to the concentrations derived from unexploded ordnance, low order detonation, or manufacturing spills). CL-20 appears to be biodegradable in soil under anaerobic conditions, and additions of organic substrates can substantially accelerate this process. However, CL-20 is not degraded in soil under aerobic conditions kept in the dark at temperatures up to 30 degrees C without organic amendments. Additions of starch or cellulose promote the biodegradation of CL-20 under aerobic conditions. Soil microbial community mediated biodegradation and plant uptake appears to enhance CL-20 biodegradation, the latter suggesting a possible route for CL-20 to entry in the food chain.     

Determination of dithiocarbamate fungicide propineb and its main metabolite propylenethiourea in airborne samples

A simple, rapid and sensitive GC–MS method for the determination of dithiocarbamate fungicide propineb [polymeric zinc propylenebis (dithiocarbamate)] and an improved HPLC procedure for the simultaneous determination of its main metabolite, propylenethiourea, and ethylenethiourea, the main metabolite of all ethylenedithiocarbamates, in airborne samples are described. The method for the analysis of propineb involves the evolution of carbon disulfide (CS₂), under acidic conditions in the presence of stannous chloride, extraction of the generated CS₂ into a layer of isooctane which is then analyzed for CS₂ content by GC–MS in SIM mode. Under the optimum conditions, the retention time of CS₂ was 1.89 min and the total time of chromatographic analysis was 5 min. Recoveries from spiking glass microfibre filters (GF/A) and silica gel filters were 86 ± 7 (n = 9) and 89 ± 4 (n = 9), respectively. The limit of detection is 0.7 ng per filter, which is equivalent to about 0.8–1.0 ng m⁻³ in air. In parallel, an HPLC method with ultraviolet detection is presented for the simultaneous analysis of the metabolites. Separation of the two metabolites was attained in less than 5 min. Recoveries from spiking GF/A and silica gel filters for ethylenethiourea were 100 ± 1 (n = 3) and 98 ± 2 (n = 3), respectively, while for propylenethiourea were 102 ± 1 (n = 3) and 98 ± 1 (n = 3), respectively. The detection limits are about 36–43 and 40–49 ng m⁻³ in air for ethylenethiourea and propylenethiourea, respectively. All the analytes spiked in the filters are proven to be stable for more than one month, at −4 °C.     

Strictly protected areas are not necessarily more effective than areas in which multiple human uses are permitted

The International Union for Conservation of Nature (IUCN) classifies protected areas into six categories, ranging from strict nature reserves to areas where multiple human uses are permitted. In the past, many researchers have questioned the effectiveness of multiple-use areas, fueling an unresolved debate regarding their conservation value. The literature so far has been inconclusive: although several studies have found that strictly protected areas are more effective, others have found the opposite, and yet others that the two types do not differ. To help resolve this debate, we reviewed the literature on protected areas and conducted our own analysis using > 19 000 terrestrial protected areas worldwide. We found that the differences between strictly protected areas and areas in which multiple human uses are permitted are often small and not statistically significant. Although the effectiveness of protected areas worldwide varies, other factors, besides their assigned IUCN category, are likely to be driving this pattern.Electronic supplementary materialThe online version of this article (10.1007/s13280-020-01426-5) contains supplementary material, which is available to authorized users.     

Ancient pests: the season of the Santorini Minoan volcanic eruption and a date from insect chitin

Attributing a season and a date to the volcanic eruption of Santorini in the Aegean has become possible by using preserved remains of the bean weevil, Bruchus rufipes, pests of pulses, from the storage jars of the West House, in the Bronze Age settlement at Akrotiri. We have applied an improved pre-treatment methodology for dating the charred insects, and this provides a date of 1744–1538 BC. This date is within the range of others obtained from pulses from the same context and confirms the utility of chitin as a dating material. Based on the nature of the insect material and the life cycle of the species involved, we argue for a summer eruption, which took place after harvest, shortly after this material was transported into the West House storeroom.     

Towards an inter-disciplinary research agenda on climate change, water and security in Southern Europe and neighboring countries

The Mediterranean and neighboring countries are already experiencing a broad range of natural and man-made threats to water security. According to climate projections, the region is at risk due to its pronounced susceptibility to changes in the hydrological budget and extremes. Such changes are expected to have strong impacts on the management of water resources and on key strategic sectors of regional economies. Related developments have an increased capacity to exacerbate tensions, and even intra- and inter-state conflict among social, political, ecological and economic actors. Thus, effective adaptation and prevention policy measures call for multi-disciplinary analysis and action.This review paper presents the current state-of-the-art on research related to climate change impacts upon water resources and security from an ecological, economic and social angle. It provides perspectives for current and upcoming research needs and describes the challenges and potential of integrating and clustering multi-disciplinary research interests in complex and interwoven human-environment systems and its contribution to the upcoming 5th assessment report of the IPCC.