Background, aim, and scope This review deals with publications concerning the mode of action of Bt proteins and their potential synergism with extrinsic factors. The aim was to assess the impact of those factors especially regarding selectivity and efficacy of Bt toxins and to discuss possible gaps in current risk assessment of genetically engineered plants expressing Bt toxins. Main features The review shows that several extrinsic factors are able to influence the selectivity and efficacy of Bt toxins. The findings are seen as being relevant for risk assessment in Bt plants. This conclusion is derived by discussing current state of knowledge about the mode of action of Bt proteins, unexpected effects on non-target organism, and the way how modified Bt toxins are expressed in genetically engineered plants. Results Several publications have been identified that show that certain factors and synergism can impact efficacy and selectivity of Bt toxins. These extrinsic factors are various and include other Bt toxins or parts from the spore of Bacillus thuringiensis as well as certain enzymes, environmental stress, non-pathogenic microorganisms, and infectious diseases. Discussion Research on the underlying mechanism of observed synergism might help to explain some of the effects found in non-target organisms. In general, possible synergism of Bt toxins with extrinsic factors can be relevant for risk assessment of genetically engineered Bt plants since they expose a modified Bt toxin to the environment under various conditions and over a long period of time. Conclusions Risk assessment of genetically engineered plants should put into question the general assumption of a high selectivity and a linear dose-response relationship in the toxicity of Bt proteins. Both selectivity and efficacy can be influenced by synergism, which can provoke unexpected and undesired effects in non-target organisms. Perspectives It is suggested that systematic research be promoted on synergism between Bt toxins and potential extrinsic factors that could impact the spectrum of susceptible organisms. This research should become a prerequisite for risk assessment of Bt plants.

Purpose The aim of this study was to compare the level of metal contamination in two bays in the middle part of the Eastern Adriatic coastal zone in Croatia using the gills of mussels Mytilus galloprovincialis as indicator tissue. Despite the existing sources of contamination, previous studies with caged mussels only indicated moderate metal contamination of the Kaštela Bay, contrary to the Trogir Bay in which marina and shipyard present a probable source of Cu- and Zn-contamination. Methods The measurements of metallothioneins (MTs) and metals that induce MT synthesis (Cu, Zn, and Cd) were performed in the heat-treated gill cytosol and total proteins (TPs) in the untreated gill cytosol. MTs were determined by differential pulse voltammetry, Cu and Zn by flame atomic absorption spectrometry (AAS), Cd by graphite furnace AAS, and TPs by Bradford spectrophotometric procedure. Results The results collected in four sampling campaigns (autumn periods from 2001 to 2004) indicated that MT levels in mussel gills (expressed on dry mass basis 2.3 ± 0.3 mg g⁻¹) were comparable with basal levels reported in the literature (2.5 ± 0.8 mg g⁻¹). Observed interindividual, temporal, and spatial MT variability could be associated with different confounding factors, such as the time of sampling, total protein concentration, and mussel size rather than cytosolic levels of Cu and Zn. Metal levels, expressed on wet mass basis, in the heat-treated gill cytosol ranged from 1.33 to 11.31 μg g⁻¹ for Zn, from 0.72 to 2.96 μg g⁻¹ for Cu, and from 0.036 to 0.100 μg g⁻¹ for Cd. The highest Zn level was measured at Vranjic (Kaštela Bay)—the site influenced by untreated domestic wastewater, while somewhat increased Zn and the highest Cu levels were found at marina and shipyard locations (Trogir Bay). The highest Cd level was measured at Inavinil (Kaštela Bay). Conclusions The observed association of gill MT levels with several biotic and abiotic factors limits its use as the biomarker of low-level metal exposure. Therefore, the use of the metal concentrations in the heat-treated gill cytosol of Mediterranean mussels should be considered for the assessment of the low-level metal contamination of coastal marine areas.

Introduction The effect of oceanic CO₂ sequestration was examined exposing a deep-sea bacterium identified as Vibrio alginolyticus (9NA) to elevated levels of carbon dioxide and monitoring its growth at 2,750 psi (1,846 m depth). Findings The wild-type strain of 9NA could not grow in acidified marine broth below a pH of 5. The pH of marine broth did not drop below this level until at least 20.8 mM of CO₂ was injected into the medium. 9NA did not grow at this CO₂ concentration or higher concentrations (31.2 and 41.6 mM) for at least 72 h. Carbon dioxide at 10.4 mM also inhibited growth, but the bacterium was able to recover and grow. Exposure to CO₂ caused the cell to undergo a morphological change and form a dimple-like structure. The membrane was also damaged but with no protein leakage.

Background, aim and scope Landfill gas (LFG) tends to escape from the landfill surface even when LFG collecting systems are installed. Since LFG leaks are generally a noticeable percentage of the total production of LFG, the optimisation of the collection system is a fundamental step for both energy recovery and environmental impact mitigation. In this work, we suggest to take into account the results of direct measurements of gas fluxes at the air-cover interface to achieve this goal. Materials and methods During the last 5 years (2004-2009), 11 soil gas emission surveys have been carried out at the Municipal Solid Waste landfill of Legoli (Peccioli municipality, Pisa Province, Italy) by means of the accumulation chamber method. Direct and simultaneous measurements of CH₄ and CO₂ fluxes from the landfill cover (about 140,000 m²) have been performed to estimate the total output of both gases discharged into the atmosphere. Three different data processing have been applied and compared: Arithmetic mean of raw data (AMRD), sequential Gaussian conditional simulations (SGCS) and turning bands conditional simulations (TBCS). The total amount of LFG (captured and not captured) obtained from processing of direct measurements has been compared with the corresponding outcomes of three different numerical models (LandGEM, IPCC waste model and GasSim). Results Measured fluxes vary from undetectable values (<0.05 mol m⁻² day⁻¹ for CH₄ and <0.02 mol m⁻² day⁻¹ for CO₂) to 246 mol m⁻² day⁻¹ for CH₄ and 275 mol m⁻² day⁻¹ for CO₂. The specific CH₄ and CO₂ fluxes (flux per surface unit) vary from 1.8 to 7.9 mol m⁻² day⁻¹ and from 2.4 to 7.8 mol m⁻² day⁻¹, respectively. Discussion The three different estimation methodologies (AMRD, SGCS and TBCS) used to evaluate the total output of diffused CO₂ and CH₄ fluxes from soil provide similar estimations, whereas there are some mismatches between these results and those of numerical LFG production models. Isoflux maps show a non-uniform spatial distribution, with high-flux zones not always corresponding with high-temperature areas shown by thermographic images. Conclusions The average value estimated over the 5-year period for the Legoli landfill is 245 mol min⁻¹ for CH₄ and 379 mol min⁻¹ for CO₂, whereas the volume percentage of CH₄ in the total gas discharged into the atmosphere varies from 29% to 51%, with a mean value of 39%. The estimated yearly emissions from the landfill cover is about 1.29 × 10⁸ mol annum⁻¹ (2,100 t year⁻¹) of CH₄ and 1.99 × 10⁸ mol annum⁻¹ (8,800 t year⁻¹) of CO₂. Considering that the CH₄ global warming potential is 63 times greater than that of CO₂ (20 a time horizon, Lashof and Ahuja 1990), the emission of methane corresponds to 130,000 t annum⁻¹ of CO₂. Recommendations and perspectives The importance of these studies is to provide data for the worldwide inventory of CH₄ and CO₂ emissions from landfills, with the ultimate aim of determining the contribution of waste disposal to global warming. This kind of studies could be extended to other gas species, like the volatile organic compounds.

Background, aim, and scope Carbonyl compounds have been paid more and more attention because some carbonyl species have been proven to be carcinogenic or a risk for human health. Plant leaves are both an important emission source and an important sink of carbonyl compounds. But the research on carbonyl compounds from plant leaves is very scarce. In order to make an approach to the emission mechanism of plant leaves, a new method was established to extract carbonyl compounds from fresh plant leaves. Materials, methods, and results The procedure combining derivatization with ultrasonication was developed for the fast extraction of carbonyl compounds from tree leaves. Fresh leaves (< 0.01 g) were minced and ultrasonicated in acidic 2,4-dinitrophenylhydrazine (DNPH)-acetonitrile solution for 30 min and then holding 30 min to allow aldehydes and ketones in leaves to react completely with DNPH. Conclusions The extraction process was performed under room temperature and only took 60 min. The advantages of this method were very little sample preparation, requiring short treatment time and usual equipment. Four greening trees, i.e., camphor tree (Cinnamomum camphora), sweet olive (Osmanthus fragrans), cedar (Cedrus deodara), and dawn redwood (Metasequoia glyptostroboides), were selected and extracted by this method. Seven carbonyl compounds, including formaldehyde, acetaldehyde, acetone, acrolein, p-tolualdehyde, m/o-tolualdehyde, and hexaldehyde were determined and quantified. The most common carbonyl species of the four tree leaves were formaldehyde, acrolein, and m/o-tolualdehyde. They accounted for 67.3% in cedar, 50.8% in sweet olive, 45.8% in dawn redwood, and 44.6% in camphor tree, respectively. Camphor tree had the highest leaf level of m/o-tolualdehyde with 15.0 ± 3.4 µg g⁻¹(fresh leaf weight), which indicated that camphor tree may be a bioindicator of the level of tolualdehyde or xylene in the atmosphere. By analyzing carbonyl compounds from different tree leaves, it is not only helpful for further studying the relationship between sink and emission of carbonyls from plants, but also helpful for exploring optimum plant population in urban greening.

Background, aim and scope In an international project named MONARPOP (Monitoring Network in the Alpine Region for Persistent and other Organic Pollutants), selected chemicals in different environmental media were analysed in the years 2004 and 2005. Seventeen pesticides were chosen and analysed in humus and mineral soil in the German Alps. The samples were taken at different altitudes. Materials and methods In such a rather complex environmental datasets, it is often necessary to compare different sets of criteria and their influence on rankings. In the similarity analysis which is part of the theory of the Hasse diagram technique, we intend to calculate the similarity of different rankings. Furthermore, we perform a so-called dominance-dominance/dominance-separability method, followed by a sensitivity analysis, both subroutines in the newly developed PyHasse programme in order to find out if the concentration of the chemicals can be related to the altitudes at which the samples were taken. Results and discussion It can be demonstrated that the altitude has a considerable influence on the concentration of some organic chemicals in humus: The concentrations of some chemicals increase with the altitude. This increase shows certain irregularities for which several explication attempts including possible effects of atmospheric stratification phenomena in valleys have been made. Conclusion These results should be complemented in further studies with MONARPOP monitoring data from other Alpine countries, e.g. Austria, Switzerland, Italy and Slovenia.

Introduction Photochemical ozone pollution of the lower troposphere (LT) is a very complex process involving meteorological, topographic emissions and chemical parameters. Ozone is considered the most important air pollutant in rural, suburban and industrial areas of many sites in the world since it strongly affects human health, vegetation and forest ecosystems, and its increase during the last decades has been significant. In addition, ozone is a greenhouse gas that contributes to climate change. For these reasons, it is necessary to carry out investigations that determine the behaviour of ozone at different locations. The aim of this work is to understand the levels and temporal variations of surface ozone in an industrial-urban region of the Southwest Iberian Peninsula. Materials and methods The study is based on ozone hourly data recorded during a 6-year period, 2000 to 2005 at four stations and meteorological data from a coastal station. The stations used were El Arenosillo and Cartaya—both coastal stations, Huelva—an urban site and Valverde—an inland station 50 km away from the coastline. The general characteristics of the ozone series, seasonal and daily ozone cycles as well as number of exceedances of the threshold established in the European Ozone Directive have been calculated and analysed. Results Analysis of the meteorological data shows that winter-autumn seasons are governed by the movement of synoptic weather systems; however, in the spring-summer seasons, both synoptic and mesoescale conditions exist. Average hourly ozone concentrations range from 78.5 ± 0.1 μg m⁻³ at Valverde to 57.8 ± 0.2 μg m⁻³ at Huelva. Ozone concentrations present a seasonal variability with higher values in summer months, while in wintertime, lower values are recorded. A seasonal daily evolution has also been found with minimum levels around 08:00 UTC, which occurs approximately 1-1.5 h after sunrise, whereas the maximum is reached at about 16:00 UTC. Furthermore, during summer, the maximum value at El Arenosillo and Valverde stations remains very uniformed until 20:00 UTC. These levels could be due to the photochemical production in situ and also to the horizontal and vertical ozone transport at El Arenosillo from the reservoir layers in the sea and in the case of Valverde, the horizontal transport, thanks to the marine breeze. Finally, the data have been evaluated relative to the thresholds defined in the European Ozone Directive. The threshold to protect human health has been exceeded during the spring and summer months mainly at El Arenosillo and Valverde. The vegetation threshold has also been frequently exceeded, ranging from 131 days at Cartaya up to 266 days at Valverde. Discussion The results in the seasonal and daily variations demonstrate that El Arenosillo and Valverde stations show higher ozone concentrations than Cartaya and Huelva during the spring and summer months. Under meteorological conditions characterized by land-sea breeze circulation, the daytime sea breeze transports the emissions from urban and industrial sources in the SW further inland. Under this condition, the area located downwind to the NE is affected very easily by high ozone concentrations, which is the case for the Valverde station. Nevertheless, according to this circulation model, the El Arenosillo station located at the coast SE from these sources is not directly affected by their emissions. The ozone concentrations observed at El Arenosillo can be explained by the ozone residual layer over the sea, similar to other coastal sites in the Mediterranean basin. Conclusions The temporal variations of the ozone concentrations have been studied at four measurement sites in the southwest of the Iberian Peninsula. The results obtained point out that industrial and urban emissions combined with specific meteorological conditions in spring and summer cause high ozone levels which exceed the recommended threshold limits and could affect the vegetation and human health in this area. Recommendations and perspectives This work is the first investigation related to surface ozone in this region; therefore, the results obtained may be a useful tool to air quality managers and policy-makers to apply possible air control strategies towards a reduction of ozone exceedances and the impact on human health and vegetation. Due to the levels, variability and underlying boundary layer dynamics, it is necessary to extend this research in this geographical area with the purpose of improving the understanding of photochemical air pollution in the Western Mediterranean Basin and in the south of the Iberian Peninsula.