Analytical protocol for the analysis of polybrominated dibenzo-dioxins and dibenzofurans: Data quality objectives and single-laboratory evaluation

An analytical protocol for the measurement of part per billion and sub-part per billion levels of PBDDs and PBDFs in selected flame retardant chemicals (polybrominated diphenyloxides; PBDPO) was developed. The fractionation/enrichment procedures were optimized to minimize the effects of the PBDPOs upon the ability to recover and measure the PBDD/PBDFs. Results from the method validation show that the current methodology is capable of accuracies ranging from 70% to 150% at the 0.1 to 10 ppb levels while larger sample sizes (from 20–200 mg to 4 g) are necessary in order to meet the EPA target Test Rule limit of quantification (LOQ) requirements.     

Chemical recognition of queen cells by honey bee workersApis mellifera (Hymenoptera: Apidae)

Summary Honey bee workers are able to nurse or to destroy and thus to recognize the capped queen cells containing a pupa. Fatty acid esters, especially methyl oleate, methyl palmitate and ethyl oleate were found in significant amounts on the queen pupal cuticle. Methyl oleate, the major component, along with smaller amounts of methyl linoleate and methyl linolenate, were involved in the recognition of queen cells by workers. In natural conditions of the colony, queen cells containing a paraffin pupal lure with methyl oleate were accepted 5.9 days by workers, releasing about 1.8 queen pupa equivalents during that period, when control cells (without ester) were kept only 2.1 days. Although these esters are non specific to honey bees, they are of great importance in social regulation of the honey bee colony.     

Emergency braking is affected by the use of cruise control

Objective: We compared the differences in the braking response to vehicle collision between an active human emergency braking (control condition) and cruise control (CC) or adaptive cruise control (ACC).

Methods: In 11 male subjects, age 22 to 67 years, we measured the active emergency braking response during manual driving using the accelerator pedal (control condition) or in condition mimicking CC or ACC. In both conditions, we measured the brake reaction time (BRT), delay to produce the peak braking force (PBD), total emergency braking response (BRT + PBD), and peak braking force (PBF). Electromyograms of leg and thigh muscles were recorded during braking. The tonic vibratory response (TVR), Hoffman reflex (HR), and M-waves were recorded in leg muscles to explore the change in sensorimotor control.

Results: No difference in PBF, TVR amplitude, HR latency, and H_max/M_max ratio were found between the control and CC/ACC conditions. On the other hand, BRT and PBD were significantly lengthened in the CC/ACC condition (240 ± 13 ms and 704 ± 70 ms, respectively) compared to control (183 ± 7 ms and 568 ± 36 ms, respectively). BRT increased with the age of participants and the driving experience shortened PBD and increased PBF.

Conclusions: In male subjects, driving in a CC/ACC condition significantly delays the active emergency braking response to vehicle collision. This could result from higher amplitude of leg motion in the CC/ACC condition and/or by the age-related changes in motor control. Car and truck drivers must take account of the significant increase in the braking distance in a CC/ACC condition.     

我国西北黄土对阿特拉津的吸附行为及影响因素

为了探讨ATZ(阿特拉津)在黄土中的吸附/解吸行为及主要影响因素,以我国西北黄土为供试土样,采用批量试验法研究了黄土对ATZ的吸附动力学和热力学行为特征. 结果表明:黄土对ATZ的吸附动力学过程更符合准二级动力学模型,吸附热力学过程更符合线性分配的Henry吸附模型(R2>0.90),吸附过程中ΔGθ(吉布斯自由能)及ΔHθ(焓变)均小于0、ΔSθ(熵变)大于0,25～45 ℃温度范围内E(吸附平均自由能)为0.86～1.30 kJ/mol,表明黄土对ATZ的吸附过程以物理吸附为主,属于自发放热过程且导致吸附体系混乱度增加. 黄土对ATZ的吸附影响因素分析结果显示,随着系统温度的升高,ATZ在黄土中的饱和吸附量下降;pH在2～10范围内变化时,ATZ在黄土中的饱和吸附量随pH的增加呈明显降低趋势;初始ρ(ATZ)从2.5 mg/L增至10.0 mg/L时,黄土对ATZ的饱和吸附量也相应地从0.082 5 mg/g增至0.621 0 mg/g. 结果显示,ATZ在黄土中的吸附速率受内部扩散、表面吸附和液膜扩散的共同影响,并且吸附过程主要受到土壤有机质疏水性分配作用的影响.      

Shift in foraging grounds and diet broadening during ontogeny in southern elephant seals from Kerguelen Islands

Highly dimorphic species like southern elephant seals (Mirounga leonina, SES hereafter) frequently exhibit resource partitioning according to sex and/or age classes. We measured carbon and nitrogen stable isotopes (δ¹³C and δ¹⁵N) of 404 blood samples (136 males and 268 females from Kerguelen Islands, 49°21′S, 70°18′E) from 2004 to 2011. Assuming that the distribution of carbon isotopes (δ¹³C value) reflects the two main foraging grounds (Polar Frontal and Antarctic Zones), we quantified the proportion of SES foraging within each zone in relation with size, a proxy for their age. We found a clear shift from Polar Frontal to Antarctic waters as male SES aged, but no relation as far as females is concerned. We also observed a widening range of nitrogen isotopic (δ¹⁵N) values, suggesting that both males and females expanded their diet spectra with age. Whereas males increased their trophic level, females remained constant on average, with some adult females feeding both at lower and at higher trophic levels than juveniles.     

Transfer parameter values in temperate forest ecosystems: a review

Compared to agricultural lands, forests are complex ecosystems as they can involve diverse plant species associations, several vegetative strata (overstorey, shrubs, herbaceous and other annual plant layer) and multi-layered soil profiles (forest floor, hemi-organic and mineral layers). A high degree of variability is thus generally observed in radionuclide transfers and redistribution patterns in contaminated forests. In the long term, the soil compartment represents the major reservoir of radionuclides which can give rise to long-term plant and hence food contamination. For practical reasons, the contamination of various specific forest products has commonly been quantified using the aggregated transfer factor (T_ag in m² kg⁻¹) which integrates various environmental parameters including soil and plant type, root distribution as well as nature and vertical distribution of the deposits. Long lasting availability of some radionuclides was shown to be the source of much higher transfer in forest ecosystems than in agricultural lands. This study aimed at reviewing the most relevant quantitative information on radionuclide transfers to forest biota including trees, understorey vegetation, mushrooms, berries and game animals. For both radiocaesium and radiostrontium in trees, the order of magnitude of mean T_ag values was 10⁻³ m² kg⁻¹ (dry weight). Tree foliage was usually 2–12 times more contaminated than trunk wood. Maximum contamination of tree components with radiocaesium was associated with (semi-)hydromorphic areas with thick humus layers. The transfer of radionuclides to mushrooms and berries is high, in comparison with foodstuffs grown in agricultural systems. Concerning caesium uptake by mushrooms, the transfer is characterized by a very large variability of T_ag, from 10⁻³ to 10¹ m² kg⁻¹ (dry weight). For berries, typical values are around 0.01–0.1 m² kg⁻¹ (dry weight). Transfer of radioactive caesium to game animals and reindeer and the rate of activity reduction, quantified as an ecological half-life, reflect the soil and pasture conditions at individual locations. Forests in temperate and boreal regions differ with respect to soil type and vegetation, and a faster decline of muscle activity concentrations in deer occurs in the temperate zone. However, in wild boar the caesium activity concentration shows no decline because of its special feeding habits. In the late phase, i.e. at least a few months since the external radionuclide contamination on feed plants has been removed, a T_ag value of 0.01 m² kg⁻¹ (fresh weight) is common for ¹³⁷Cs in the muscles of adult moose and terrestrial birds living in boreal forests, and 0.03 m² kg⁻¹ (fresh weight) for arctic hare. Radiocaesium concentrations in reindeer muscle in winter may exceed the summer content by a factor of more than two, the mean T_ag values for winter ranging from 0.02 to 0.8 m² kg⁻¹ (fresh weight), and in summer from 0.04 to 0.4 m² kg⁻¹. The highest values are found in the year of initial contamination, followed by a gradual reduction. In waterfowl a relatively fast decline in uptake of ¹³⁷Cs has been found, with T_ag values changing from 0.01 to 0.002 m² kg⁻¹ (fresh weight) in the three years after the contaminating event, the rate being determined by the dynamics of ¹³⁷Cs in aquatic ecosystems.     

Environmental release of dioxins from reservoir sources during beach nourishment programs

In late 1990s, USEPA/FDA made an important connection regarding the presence of elevated levels of dioxins (e.g., 1500 ng kg⁻¹ TEQ) in ball clays mined in Mississippi (USA) from a geological deposit dated to ∼40 million years (Mississippi Embayment) that stretches over several states (northern part of Mississippi to Kentucky) and levels of dioxins in selected animal food sources. Following a recent beach nourishment program along the mid-Atlantic coast of the US, a number of dark gray, blue tinted nuggets of varying sizes were found on beach strands and near the shoreline. Using the presence of these balls of clay (shape, color, and knowledge regarding their use in pottery) on the beach, together with our direct experience analyzing ball clays for dioxins, we made a possible association between these clays and elevated dioxins. Concerns regarding the potential of nourishment programs to cause severe damage to our beaches drove us to test the dioxin content of nourishment exposed clays. A number of the nuggets, along with freshly dredged and deposited sand (collected the morning after nourishment) with the same coloration, and others (sun-bleached), collected approximately 2 weeks after the completion of the nourishment efforts, were analyzed for the presence of PCDD/Fs, PCBs, and selected semi-volatile chlorinated organics. The clay PCDD/F WHO2005-TEQs (dry weight; ND = DL; EMPC = EMPC) ranged from 0.41 to 5.78 ng kg⁻¹ with an average of 2.64 ng kg⁻¹, whereas the sand sample’s TEQs ranged from 0.18 to 0.31 ng kg⁻¹ PCDD/F WHO-2005, with an average of 0.22 ng kg⁻¹. The average total tetra- through octachlorinated dibenzo-p-dioxin concentration was 2700 ng kg⁻¹ (with a maximum of 5800 ng kg⁻¹) for the clays and 8.5 ng kg⁻¹ (with a maximum of 16.8 ng kg⁻¹) for the sand samples. The congener 2,3,7,8-TCDD (TEF = 1) was detected in half of the clay samples (0.11-0.77 ng kg⁻¹). All of the clay and sand samples displayed an unambiguous and dominating 1,4,6,9-chlorination pattern across homolog groups. No other chlorinated aromatics were detected above background levels. The observations, along with the absence or an extremely low level of polychlorinated dibenzofurans, together with the mineralogical analysis, supports the conclusion that off-shore dredging activities are reaching reservoir sources containing dioxin-tainted, smectic/kaolinite clay minerals. Subsequent beach erosion provides additional environmental releases over time, as buried balls of clay from previous nourishment efforts become exposed.     

Democratic Debate and Mediated Discourses on Climate Change: From Consensus to De/politicization

Starting from a risk conflicts perspective, this article challenges two common assumptions of existing research on climate change in public and media discourses. It argues that the evaluation of these discourses on the extent to which these either accurately reflect a scientific consensus or contribute to achieving social consensus insufficiently takes account of the exclusionary mechanisms it starts from. A conceptual and empirical framework is subsequently put forward which allows one to evaluate mediated discourses in terms of the extent to which democratic debate and citizenship are encouraged. Such analysis can reveal the discursive strategies underlying processes of politicization and depoliticization. This perspective is illustrated by an analysis of a local case study: the “Sing for the Climate” campaign. We conclude by calling for a broad systematic research agenda revealing the extent to which de/politicizing discourses are found to influence public and media discourses.     

Control of Claus Plant Sulfur Compound Emissions

The body of information of this paper is directed to those individuals charged with selecting a process to control atmospheric sulfur emissions from Claus plants serving refineries, gas processing installations, and chemical plants. The TGT process developed by the French Petroleum Institute (IFP) is an extension of the Claus reaction itself in the liquid phase. Mixed H₂S and SO₂ in tail gas from Claus units is fed to a packed tower in which a solution of proprietary catalyst in a high BP polyglycol circulates countercurrent to the gas flow. The mixed gases react with the catalyst to form a complex, which in turn reacts with more gases to produce elemental sulfur. Reaction temperature keeps the sulfur above its melting point. Product accumulates in the boot of the tower and is drawn off continuously through a seal leg.

The IFP TGT process is simple in design and units have simple construction, characterized by use of low carbon steel and the use of very few pieces of equipment. Of all processes used today to take effluent sulfur values down to 1000 ppm SO₂ after incineration, the IFP TGT process requires the least capital investment and the lowest operating costs. Twenty-six full scale plants are operating or under design or construction: nine each in the U.S. and Japan, five in the U.S.S.R. and Poland, two in western Europe and one in Canada. Capacities of the Claus plants served range from 45 to 800 Lt/d sulfur.