Seasonal variations of cadmium and zinc in Arrhenatherum elatius, a perennial grass species from highly contaminated soils

There is interest in studying bioaccumulation in plants because they form the base of the food chain as well as their potential use in phytoextraction. From this viewpoint, our study deals with the seasonal variation, from January to July, of Cd and Zn bioaccumulation in three metallicolous populations of Arrhenatherum elatius, a perennial grass with a high biomass production. In heavily polluted soils, while Zn bioaccumulation is weak, A. elatius accumulates more Cd than reported gramineous plants, with concentration of up to 100 microg g(-1). Our results also showed seasonal variations of bioaccumulation, underlying the necessity for in situ studies to specify the date of sampling and also the phenology of the collected plant sample. In our experimental conditions, accumulation is lower in June, leading us to the hypothesis of restriction in heavy metals translocation from roots to aerial parts during seed production.     

Patterns of metal soil contamination and changes in terrestrial cryptogamic communities

Correlations between terricolous bryophyte- and lichen- vegetation and edaphic parameters (pH, organic matter, nitrogen, Carbon/nitrogen ratio, Cation Exchange Capacity, and Cd, Pb and Zn soil contents) of soils submitted to a gradient of metal contamination in northern France were performed using statistical analysis. Six classes can be distinguished according to the low-, intermediate- and high-trace metal levels respectively, leading to the conclusion that bryophyte- and lichen-groupings have a strong bioindicative value of the heavy metal pollution of soils.     

TCE recovery mechanisms using micellar and alcohol solutions: phase diagrams and sand column experiments

Forty-one phase diagrams and fifteen sand column experiments were conducted to evaluate the efficiency of three types of washing solutions to recover trichloroethylene (TCE) at residual saturation and to identify the recovery mechanisms involved. This study demonstrates that: (1) an alcohol and a surfactant combination is more efficient than an alcohol used alone in water; (2) the prediction of the dominant recovery mechanism from the tie line slopes in phase diagram is accurate and can be reproduced in sand column experiments; and (3) TCE recovery efficiency in sand column experiments is generally well represented by the position of the miscibility curve in phase diagrams in the low concentration range. However, the miscibility curve alone is not sufficient to exactly predict the TCE recovery mechanisms involved. Tie line slopes and the critical tie line have to be taken into consideration to select the active matter as well as its concentration and to predict the dominant recovery mechanism in sand column experiments. The sand column experiments quantified the recovery efficiency of each solution and identified the proportion of the recovery mechanisms (mobilisation vs. solubilisation). Washing solutions with an active matter concentration above the critical tie line caused dominating mobilisation. Mobilisation was also dominant when the active matter of the washing solution partitioned into the organic phase and the active matter concentration was below the critical tie line. Solubilisation and emulsification were dominant for washing solutions containing active matter, which principally partitioned into the aqueous phase and an active matter concentration below the critical tie line.     

Oil-Mineral Aggregate Formation on Oiled Beaches: Natural Attenuation and Sediment Relocation

The significance of oil-mineral aggregate (OMA) formation on the effectiveness of the in situ shoreline treatment options of natural attenuation (natural recovery) and sediment relocation (surf washing) was examined during field trials on two mixed-sediment (sand and pebble) beaches experimentally oiled with IF-30 oil. At both sites, the amount of oil remaining in the experimental plots was dramatically reduced within five days after sediment relocation treatments. Time-series microscopy and image analysis of breaker-zone water samples demonstrate that OMA formation occurred naturally on the oiled beaches at both sites and was accelerated by the sediment relocation procedure. Lower concentrations of OMA in the breaker zone at Site 3 are attributed to the higher wave-energy levels at this site that presumably facilitated more rapid OMA dispersion. The granulometry and mineralogy of beach sediment and of subtidal sediment trap samples indicate that the material settling in nearshore waters originated from the relocated sediment and that a portion of the finer sediment was probably transported out of the study region before settling. Gas chromatography/mass spectrometry analysis demonstrated that a significant fraction of the oil dispersed into nearshore waters and sediments by interaction with mineral fines was biodegraded. The fact that little or no residual oil was found stranded on the shore in areas adjacent to the experimental plots and that only small amounts of oil were found in nearshore subtidal sediments and sediment trap samples suggests that a large fraction of the oil lost from the experimental plots may have been dispersed in the form of relatively buoyant OMA.     

The role of microgynes in the reproductive strategy of the neotropical ant <Emphasis Type="Italic">Ectatomma ruidum</Emphasis>

Miniaturized queens, microgynes, are regarded as an alternative reproductive strategy sparsely present through the ant world. The described roles of miniaturized queens include alternative short-distance dispersal morphs, an adaptation to polygyny and inquiline parasites. Some of these inquiline parasite microgynes have been described as a separate species from their host. In the poneromorph group, miniaturized queens are only reported in two Mexican populations of two Ectatomminae: Ectatomma tuberculatum, in which small queens represent an inquiline species (Ectatomma parasiticum) and Ectatomma ruidum. E. ruidum presents apparently facultative polygyny with microgynes. We used mitochondrial DNA markers and newly developed microsatellite loci to investigate the status as well as the role of microgynes in E. ruidum. We confirmed that microgynes and macrogynes are from the same species. This species is almost exclusively monogynous and monoandrous, supernumerary dealate queens of both types being actually daughters of the mother queen. An apparently polygynous nest was more often headed by a macrogyne than a microgyne. We didn't find any inbreeding or isolation by distance in the studied population, indicating that new gynes are inseminated by unrelated males and can establish a new nest far from their natal nest. However, re-adoption of daughter queens seems to be the rule and rate of microgyny appears to be linked to nest density and environmental factors.     

Microstructures of Antarctic cidaroid spines: diversity of shapes and ectosymbiont attachments

The echinoderm endoskeleton, located in the connective layer of the tegument, is organized into a three-dimensional mesh, the stereom. Among echinoids, the cidaroids depart from this pattern, and the shaft of the spine lacks an epidermis. Thus, the spines lack antifouling protection, allowing ectosymbionts such as bryozoans and foraminiferans to attach. This raises a question about the adaptive role of the cortical layer of the stereom. This study examined the micro- and mesostructure of the spines of 11 cidaroid species collected in the Weddell Sea and Drake Passage, and the nature of their ectosymbiont attachments. Scanning electron microscopy was used to characterize the cortex surface and X-ray micro computed tomography (μCT) to describe the symbiont attachments. Spine microstructure features provide a useful taxonomic character for distinguishing among three species in the genus Ctenocidaris, and challenge a previous parasitic interpretation of cortical filaments on the spines of Rhynchocidaris triplopora. Ectosymbiont attachments were classified as Anchoring, Molding, Cementing, or Corroding. The study suggests that some microstructure features may be protective, keeping the ectosymbionts away from the cortex and loosely attached at intervals along the shaft of the spine, while other micro-structures facilitate attachment over considerable areas of the shaft. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

Intertidal Zone Management in the Western Indian Ocean: Assessing Current Status and Future Possibilities Using Expert Opinions

This expert opinion study examined the current status of the intertidal zone in the Western Indian Ocean (WIO) and ranked and discussed future management approaches. Information was gathered from scientists, practitioners, and managers active in the WIO region through a questionnaire and a workshop. The experts stated that the productive intertidal environment is highly valuable for reasons such as recreation, erosion protection, and provision of edible invertebrates and fish. Several anthropogenic pressures were identified, including pollution, harbor activities, overexploitation, and climate change. The experts considered the WIO intertidal zone as generally understudied, undermanaged, and with poor or no monitoring. The most important management strategies according to the expert opinions are to develop and involve local people in integrated coastal zone management (ICZM), to increase knowledge on species–environment relationships, and to develop awareness campaigns and education programs. To improve coastal environmental management and conservation, we argue that the intertidal zone should be treated as one organizational management unit within the larger framework of ICZM.

Electronic supplementary material

The online version of this article (doi:10.1007/s13280-013-0465-8) contains supplementary material, which is available to authorized users.     

Characterization of Airborne Dust from Two Nonferrous Foundries by Physico-chemical Methods and Multivariate Statistical Analyses

Abstract

Airborne particulate matter was sampled at a copper smelter and at an aluminum casting plant. Size, shape, quantity, and microlocalization of chemical species in the particulates were measured using closed cassettes, cascade impactors, scanning electron microscopy, X-ray diffraction, infrared and atomic absorption spectrophotometries, secondary ion mass spectrometry, and photoelectron spectroscopy. Cluster and principal components analyses were used in interpreting results. Aerosol chemistry varies as a function of size, and composition becomes more complex as the aerosol size drops into the respirable fraction and lower. Surface chemical properties are evidenced where, generally, volatile species are enriched. A few site-specific elements and characteristics were identified. The formation of particulates may often be related to process and practices, yet the actual distribution of species in the air remains an intricate matter.