Increased environmental gamma-ray dose rate during precipitation: a strong correlation with contributing air mass

It has long been observed that the environmental gamma-ray dose rate increases noticeably during precipitation intervals. This increase, due to the presence of radon progeny in the rain droplets (or snow flakes), can affect the reliability of the monitoring of artificial radioactivity and long term estimates of exposure to ambient natural radionuclides in surveillance network. Predicting the amplitude of the dose increase has been shown to be surprisingly challenging. In this work, standard air mass back trajectory analysis is used to show that the amplitude of the increase can be quantitatively linked to the history of the air mass where the precipitation is occurring. Furthermore, we show how back trajectory analysis, environmental gamma and rain data can be used to obtain estimations of relative radon emanation rates for locations far from the actual point of detection.     

Antimicrobial effects of clofibrate on the wheat pathogen Fusarium culmorum

Abstract

The biological effects of clofibrate (ethyl p‐chlorophenoxy‐isobutyric acid) on the growth and metabolism of the soil‐borne wheat pathogen Fusarium culmorum, were examined.

In mid log phase (16 hr) cultures both phenylalanine uptake and secondary spore production were stimulated at 0.1 μM concentration; the net sterol content was reduced 50% at 0.35 μM; oxygen uptake was stimulated at 0.1 mM; growth was inhibited 50% at 0.1 mM concentration. Both phenylalanine and oxygen uptake were inhibited at 1.0 mM and pyruvate dehydrogenase activity was reduced 50% at 50 mM concentration of clofibrate.

The data indicate that clofibrate affects a number of biological and enzyme systems. The inhibitory effect on the growth of the pathogen suggest a potential use of hypolipidemic agents like clofibrate as an antifungal agent for seed protection.     

Trace Metals in Upland Headwater Lakes in Ireland

Trace elements (n = 23) in Irish headwater lakes (n = 126) were investigated to determine their ambient concentrations, fractionation (total, dissolved, and non-labile), and geochemical controls. Lakes were generally located in remote upland, acid-sensitive regions along the coastal margins of the country. Total trace metal concentrations were low, within the range of natural pristine surface waters; however, some lakes (~20 %) had inorganic labile aluminum and manganese at levels potentially harmful to aquatic organisms. Redundancy analysis indicated that geochemical weathering was the dominant controlling factor for total metals, compared with acidity for dissolved metals. In addition, many metals were positively correlated with dissolved organic carbon indicating their affinity (or complexation) with humic substances (e.g., aluminum, iron, mercury, lead). However, a number of trace metals (e.g., aluminum, mercury, zinc) were correlated with anthropogenic acidic deposition (i.e., non-marine sulfate), suggesting atmospheric sources or elevated leaching owing to acidic deposition. As transboundary air pollution continues to decline, significant changes in the cycling of trace metals is anticipated.     

Can further mitigation of ammonia emissions reduce exceedances of particulate matter air quality standards?

Several studies point out the importance of agricultural emissions to particulate matter (PM) concentrations, and particularly of NH₃ emissions to PM_2.5. Our study used three different chemical transport models (CHIMERE, EMEP and LOTOS-EUROS) to quantify the reductions of PM_2.5 and PM₁₀ concentrations due to reductions of NH₃ emissions beyond the Gothenburg Protocol (GP), as well as due to the GP alone compared to 2009. Simulations of PM_2.5 and PM₁₀ concentrations using 2009 meteorology were undertaken for five emission scenarios: 2009 emissions (as the reference simulation), GP emissions in 2020, and further 10%, 20% and 30% NH₃ emission reductions in EU27 beyond the GP. The modelling results for the scenarios with further 10%, 20% and 30% NH₃ agriculture emission reductions in EU27 beyond the GP show that the reduction achieved in PM concentrations is not linear with the emission reductions. In fact, the results from the study show that the impact of ammonia emissions reduction is significantly more efficient when the emission reduction rises. Moreover, based on the evaluation on 2009, the modelling study shows that the expected impact of ammonia emissions on the formation of particulate ammonium was underestimated by all models. This would imply that the role of ammonia on PM concentration and exceedances of PM_2.5 and PM₁₀ limit values is likely to be even larger than quantified in this study. This study shows that the implementation of the emission reductions imposed by the revised GP for 2020 will not suffice to achieve compliance with PM limit values everywhere in Europe; hence further European and local measures may be considered. NH₃ emissions from agriculture can be further reduced with the implementation of proven and feasible measures (substitution of fertilizers, improved storage of manure, way fertilizer injections, etc., …), in order to reduce PM concentrations and their impacts on human health across Europe.     

Industrial pollution transport. Part 2. Control of industrial emissions

Solutions of the pollution transport problem and its adjoint are used to monitor mean pollution concentration in an ecologically important zone. Four strategies of control over pollutants released into the atmosphere by industrial plants are suggested. They differ by the restrictions imposed on the emission rate of each plant. All the strategies use solutions of the adjoint transport problem and assure the fulfillment of the sanitary norm in the zone. A linear interpolation of these strategies also brings pollution level in the zone down to the sanitary norm. A method of detecting the plants violating the prescribed emission rates is also given. A simple example is given to illustrate the strategies suggested.     

Remediating Over-Produced and Contaminated Aquifers by Artificial Recharge from Surface Waters

Recharging from open-surface water resources is investigated as a method for remediation of over-produced and contaminated aquifers. The hydraulic and contaminant modeling using the Modflow-2000 and MT3DMS simulation software are resorted for evaluation of the available options. Methodology is developed and illustrated for reviewing the alternative remediation approaches for optimal selection of the best remediation approach to aquifer recharging from surface waters. The effectiveness of the present systematic approach is demonstrated by identifying the best choice among the multifunctional artificial recharge options available for the Great Forest Park in Debrecen, Hungary.     

Multicompartmental fate of persistent substances

Background, Aim and Scope Modelling of the fate of environmental chemicals can be done by relatively simple multi-media box models or using complex atmospheric transport models. It was the aim of this work to compare the results obtained for both types of models using a small set of non-ionic and non-polar or moderately polar organic chemicals, known to be distributed over long distances. Materials and Methods Predictions of multimedia exposure models of different types, namely three multimedia mass-balance box models (MBMs), two in the steady state and one in the non-steady state mode, and one non-steady state multicompartment chemistry-atmospheric transport model (MCTM), are compared for the first time. The models used are SimpleBox, Chemrange, the MPI-MBM and the MPI-MCTM. The target parameters addressed are compartmental distributions (i.e. mass fractions in the compartments), overall environmental residence time (i.e. overall persistence and eventually including other final sinks, such as loss to the deep sea) and a measure for the long-range transport potential. These are derived for atrazine, benz-[a]-pyrene, DDT, α and γ-hexachlorocyclohexane, methyl parathion and various modes of substance entry into the model world. Results and Discussion Compartmental distributions in steady state were compared. Steady state needed 2–10 years to be established in the MCTM. The highest fraction of the substances in air is predicted by the MCTM. Accordingly, the other models predict longer substance persistence in most cases. The results suggest that temperature affects the compartmental distribution more in the box models, while it is only one among many climate factors acting in the transport model. The representation of final sinks in the models, e.g. burial in the sediment, is key for model-based compartmental distribution and persistence predictions. There is a tendency of MBMs to overestimate substance sinks in air and to underestimate atmospheric transport velocity as a consequence of the neglection of the temporal and spatial variabilities of these parameters. Therefore, the long-range transport potential in air derived from MCTM simulations exceeds the one from Chemrange in most cases and least for substances which undergo slow degradation in air. Conclusions and Perspectives MBMs should be improved such as to ascertain that the significance of the atmosphere for the multicompartmental cycling is not systematically underestimated. Both types of models should be improved such as to cover degradation in air in the particle-bound state and transport via ocean currents. A detailed understanding of the deviations observed in this work and elsewhere should be gained and multimedia fate box models could then be ‘tuned in’ to match better the results of comprehensive multicompartmental transport models. ESS-Submission Editor: Prof. Dr. Michael Matthies (matthies@uos.de)     

Geochemical and solute transport modelling for CO2 storage, what to expect from it?

Geochemistry plays an important role when assessing the impact of CO₂ storage. Due to the potential corrosive character of CO₂, it might affect the chemical and physical properties of the wells, the reservoir and its surroundings and increase the environmental and financial risk of CO₂ storage projects in deep geological structures. An overview of geochemical and solute transport modelling for CO₂ storage purposes is given, its data requirements and gaps are highlighted, and its progress over the last 10 years is discussed. Four different application domains are identified: long-term integrity modelling, injectivity modelling, well integrity modelling and experimental modelling and their current state of the art is discussed. One of the major gaps remaining is the lack of basic thermodynamical and kinetic data at relevant temperature and pressure conditions for each of these four application domains. Real challenges are the coupled solute transport and geomechanical modelling, the modelling of impurities in the CO₂ stream and pore-scale modelling applications.     

Comparisons of two serious air pollution episodes in winter and summer in Beijing

Characteristics of two serious air pollution episodes(9–15 January, as the winter case; and30 June to 1 July, as the summer case), which occurred in Beijing in 2013 were investigated and compared using multi-method observations and numerical simulations. During these two air pollution episodes, PM_(2.5) concentrations varied significantly within Beijing, with PM_(2.5) concentrations in southern parts of Beijing being significantly higher than in northern areas. Typically, heavy air pollution episodes begin in the southern parts and disperse towards the northern parts of Beijing. Clearly, synoptic patterns and the stability of atmospheric circulation patterns were the main factors controlling air pollution in Beijing.During the winter case, a warm center above 900 h Pa occurred over Beijing. Meanwhile, in the summer case, although there was only a weak inversion, the convective inhibition energy was strong(over 200 J/k G). This clearly influenced the duration of the air pollution event. Except for the local accumulation and secondary atmospheric reactions in both cases, regional straw burnings contributed a lot to the PM_(2.5) concentrations in summer case.Using the CAMxmodel, we established that regional transport contributed almost 59% to the PM_(2.5) averaged concentration in Beijing in the winter case, but only 31% in the summer case. Thus, the winter case was a typical regional air pollution episode, while the summer case resulted from local accumulation straw burnings transportation and strong secondary atmospheric reactions. Given that air pollution is a regional problem in China, consistent and simultaneous implementation of regional prevention and control strategies is necessary to improve regional air quality.