Significance of small-scale spatio-temporal heterogeneity in phytoplankton abundance for energy flow in Mytilus edulis

The effect of small-scale heterogeneity of phytoplankton abundance on mussel (Mytilus edulis L.) energy flow was studied by comparing filtration rate, consumption and assimilation efficiency in two groups of mussels fed under constant (control) and fluctuating (24 min) seston regimes of the same average. The experiment was carried out twice. Mussels appeared to regulate their filtration rate in response to varying seston concentration in one experiment, but not in the other. This behavioral difference may have been caused by differences in mean food level. Mean consumption was not different in the two feeding regimes, but assimilation efficiency was probably lower under fluctuating seston concentration. This suggests that small-scale heterogeneity in phytoplankton abundance would not affect the total transfer of energy between plankton and benthos. However, since a higher proportion of consumed energy was probably lost as faeces and/or pseudofaeces under the fluctuating seston regime, it may be expected that growth rate of mussels is depressed by small-scale heterogeneity in phytoplankton availability.Contribution to the programme GIROQ (Groupe interuniversitaire de recherches océanographiques du Québec)     

Sources and historical record of tin and butyl-tin species in a Mediterranean bay (Toulon Bay,France)

Concentrations of inorganic tin (Sn_inorg), tributyltin (TBT) and its degradation products dibutyltin (DBT) and monobutyltin (MBT) were measured in surface sediments and in two cores from the Toulon Bay, hosting the major French military harbour. Anticipating planned dredging, the aim of the present work is to map and evaluate for the first time the recent and historic contamination of these sediments by inorganic and organic Sn species derived from antifouling paints used for various naval domains including military, trade, tourism and leisure. Tin and butyl-Sn concentrations in the bay varied strongly (4 orders of magnitude), depending on the site, showing maximum values near the shipyards. The concentrations of total Sn (1.3–112 μg g^?1), TBT (<0.5–2,700 ng g^?1), DBT (<0.5–1,800 ng g^?1) and MBT (0.5–1,000 ng g^?1) generally decreased towards the open sea, i.e. as a function of both distance from the presumed main source and bottom currents. Progressive degradation state of the butyl-Sn species according to the same spatial scheme and the enrichment factors support the scenario of a strongly polluted bay with exportation of polluted sediment to the open Mediterranean. Low degradation and the historical records of butyl-Sn species in two ²¹⁰Pb-dated sediment cores, representative of the Northern Bay, are consistent with the relatively recent use of TBT by military shipyards and confirm maximum pollution during the 1970s, which will persist in the anoxic sediments for several centuries. The results show that (a) degradation kinetics of butyl-Sn species depend on environmental conditions, (b) the final degradation product Sn_inorgBT is by far the dominant species after 10–12 half-life periods and (c) using recent data to reliably assess former TBT contamination requires the use of a modified butyl-Sn degradation index BDI_mod. Resuspension of extremely contaminated subsurface sediments by the scheduled dredging will probably result in mobilization of important amounts of butyl-Sn species.     

Occupational exposure in the fluorescent lamp recycling sector in France

The fluorescent lamp recycling sector is growing considerably in Europe due to increasingly strict regulations aimed at inciting the consumption of low energy light bulbs and their end-of-life management. Chemical risks were assessed in fluorescent lamp recycling facilities by field measurement surveys in France, highlighting that occupational exposure and pollutant levels in the working environment were correlated with the main recycling steps and processes.The mean levels of worker exposure are 4.4 mg/m³, 15.4 μg/m³, 14.0 μg/m³, 247.6 μg/m³, respectively, for total inhalable dust, mercury, lead and yttrium. The mean levels of airborne pollutants are 3.1 mg/m³, 9.0 μg/m³, 9.0 μg/m³, 219.2 μg/m³, respectively, for total inhalable dust, mercury, lead and yttrium. The ranges are very wide. Surface samples from employees’ skin and granulometric analysis were also carried out. The overview shows that all the stages and processes involved in lamp recycling are concerned by the risk of hazardous substances penetrating into the bodies of employees, although exposure of the latter varies depending on the processes and tasks they perform. The conclusion of this study strongly recommends the development of a new generation of processes in parallel with more information sharing and regulatory measures.     

Performance Assessment of a 3D Hydrodynamic Model Using High Temporal Resolution Measurements in a Shallow Urban Lake

Urban lakes provide many ecosystem services, e.g., flood control, nature protection, coolness island, recreation. Hydrodynamic models will increasingly be used to enhance these benefits. We present the first validation of a three-dimensional (3D) hydrodynamic model on a small shallow lake with high resolution and high frequency measurements. Lake Créteil, France (area 0.4 km², mean depth 4.5 m, and catchment area 1 km²) is a former gravel pit and now part of a regional park. The model Delft3D-FLOW was calibrated on a one-month period, with continuous measurements of temperature at five depths at the center of the lake and at three depths at two other stations, and with current speed profiles at the centre of the lake. The model was then verified on 18 1-month periods with similar temperature measurements. The model reproduced very well the temperature dynamics, including the alternation between mixing and stratification periods and internal wave patterns. The mean absolute errors over the five depths at the central point remained below 0.55^°C in spring and summer, the most favorable seasons for phytoplankton growth. Horizontal temperature differences, which rose up to 3^°C at the beginning of stratification periods, were also well reproduced, as well as current speeds. These results are very promising for assessing nutrient and pollutant diffusion, settling and resuspension, as well as for understanding how phytoplankton blooms start in small shallow lakes.     

A case study on raw material blending for the recycling of ferrous wastes in a blast furnace

The utilisation of ferrous wastes in a blast furnace is a well established recycling process to cope with the enormous amounts of ferrous residues in the iron and steel industry. The further input flows of this process, that is especially coke and fluxes, as well as its output flows, that is pig iron and by-products, are highly dependent on the blending of the ferrous wastes while they differ highly in the revenues gained for the treatment and their chemical composition. So far, no planning approach exists for the blending of the residues on the operational planning level that models the dependency of the costs and revenues on the raw material blend and the thermodynamic reactions in the recycling processes adequately. Therefore we present an approach for this operational production planning problem focusing on an integration of such a sufficiently detailed modelling of the underlying metallurgical processes into the planning model. The basis of our approach is a thermodynamic simulation of the processes. From this simulation we derive linear input-output functions for the relevant material and energy flows by using multiple linear regression. These input–output functions form the core of our blending model developed for the planning task. The model is implemented as an integrated decision support system. Exemplary application results are given. These results validate the approach and show that ecological the economic optimisation leads also to results which are advantageous in terms of resource efficiency and emission reduction. Though developed for a specific recycling process, the methodology can be transferred to other metallurgical (recycling) processes, as well as other parts of the process industries, and is therefore of high relevance.     

Life cycle assessment of hydrotreated vegetable oil from rape,oil palm and Jatropha

A life cycle assessment of hydrotreated vegetable oil (HVO) biofuel was performed. The study was commissioned by Volvo Technology Corporation and Volvo Penta Corporation as part of an effort to gain a better understanding of the environmental impact of potential future biobased liquid fuels for cars and trucks. The life cycle includes production of vegetable oil from rape, oil palm or Jatropha, transport of the oil to the production site, production of the HVO from the oil, and combustion of the HVO. The functional unit of the study is 1 kWh energy out from the engine of a heavy-duty truck and the environmental impact categories that are considered are global warming potential (GWP), acidification potential (AP), eutrophication potential (EP) and embedded fossil production energy. System expansion was used to take into account byproducts from activities in the systems; this choice was made partly to make this study comparable to results reported by other studies. The results show that HVO produced from palm oil combined with energy production from biogas produced from the palm oil mill effluent has the lowest environmental impact of the feedstocks investigated in this report. HVO has a significantly lower life cycle GWP than conventional diesel oil for all feedstocks investigated, and a GWP that is comparable to results for e.g. rape methyl ester reported in the literature. The results show that emissions from soil caused by microbial activities and leakage are the largest contributors to most environmental impact categories, which is supported also by other studies. Nitrous oxide emissions from soil account for more than half of the GWP of HVO. Nitrogen oxides and ammonia emissions from soil cause almost all of the life cycle EP of HVO and contribute significantly to the AP as well. The embedded fossil production energy was shown to be similar to results for e.g. rape methyl ester from other studies. A sensitivity analysis shows that variations in crop yield and in nitrous oxide emissions from microbial activities in soil can cause significant changes to the results.     

Volatile organic compounds and host-plant specialization in European corn borer E and Z pheromone races

Plant volatile cues are considered the main source of information for ovipositing moths, which use chemical information to locate and recognize the host plant. In Europe, two sympatric populations of European corn borer (ECB; Ostrinia nubilalis, Hübner), the Z and E-pheromone races, feed mainly on maize and hop or mugwort, respectively. We studied the mechanisms of host-plant recognition and fidelity in ECB pheromone races by testing the attractiveness of host plants to gravid females in a flight tunnel and by analyzing the volatiles released from maize, mugwort, and hop during the scotophase, when the ovipositing flight of the ECB females occurs. In the wind tunnel bioassay, the Z-race and E-race females engaged in upwind flight and expressed a strong host fidelity to their respective main host plants; all three of these host plants possess distinctive volatile profiles specific as to blend and ratio. The host plants shared a certain number of ubiquitous volatiles present in various ratios that likely constitute a species-specific cue to host-seeking ECB moths. Our observations therefore suggest that ECB host fidelity is steered by plant volatiles that are present in species-specific ratios of ubiquitous volatile organic compounds.