Assessment of Trace Metals in the Sediments From the Coastal Zone of Alexandria,Egypt

Freshly deposited surface sediments from the Alexandria coastal zone were collected and analysed in 1995 for their trace metal concentrations. Metal concentrations in the sediments vary between sites within a wide range for copper, zinc, iron, lead, chromium and cadmium. the statistical analysis between the metal concentrations and the different constituents (organic carbon, total nitrogen, silt, clay and total iron) showed significant correlations. the enrichment factors for the sediments ranged between 3 and 4-fold for copper, chromium and zinc and reached up to 9-fold for lead and 113-fold for cadmium. the highest index for cadmium and lead may be attributed to the anthropogenic inputs from the surrounding area, where they are highest in lower discharge areas.     

“Armpit effect” in an African cichlid fish: self-referent kin recognition in mating decisions of male Pelvicachromis taeniatus

Kin discrimination in nepotistic as well as in sexual contexts is widespread in animals including humans. However, the underlying mechanisms of kin discrimination are assumed to vary between species and—within species—between contexts. During solitary life stages, kin recognition based on social learning is assumed to be less reliable because kin templates that are not continuously updated may get lost. Therefore, self-referent phenotype matching (“armpit effect”), i.e., the comparison of unknown phenotypes with own characteristics, should be particularly relevant when no social cues are available. However, experimental evidence for this mechanism is scarce. Here, we examine self-referent kin recognition in a mate-choice context in adult male Pelvicachromis taeniatus, a socially monogamous cichlid fish from West Africa with biparental brood care and pronounced kin-mating preferences. Juvenile P. taeniatus live in groups, whereas adult males compete for access to breeding sites which they aggressively defend against rivals. Using computer-animated females as standardized visual stimuli in combination with olfactory cues of related and unrelated females, we show that adult males reared isolated from kin since egg stage were able to discriminate sisters from unrelated females. As males could have learned kin cues only from themselves, our study provides evidence for self-referent kin recognition and indicates that the observed inbreeding preferences are mediated by self-derived olfactory cues. Male preferences for sisters were correlated with male body size. We discuss the implications of quality-related mate choice for the evolution of kin-mating preferences.     

Nuclear contamination sources in surface air of Finnish Lapland in 1965–2011 studied by means of 137Cs, 90Sr,and total beta activity

Environmental Science and Pollution Research - Radionuclides 137Cs and 90Sr and total beta activity were determined from air filters collected in Rovaniemi (Finnish Lapland) in 1965–2011....     

Influence of seasons,air mass origin and day of the week on size-segregated chemical composition of aerosol particles at a kerbside

The size-segregated chemical composition of atmospheric aerosol particles (aerodynamic diameter Dp_aer = 0.05–10 μm) was studied to reveal differences between seasons (winter/summer), air mass origins (East/West/North), and days of the week (weekday/Sunday). The goal was to identify the different particle emission sources for the first time at a kerbside in the city of Dresden, Germany.Ultra-fine particles (Dp_aer = 0.05–0.14 μm, 12% of PM₁₀) consisted of approximately 80% OM (organic matter) and EC (elemental carbon), while fine particles (Dp_aer = 0.14–1.2 μm) comprised about 55% ionic compounds with 44% OM and EC. The coarse fraction (Dp_aer = 1.2–10 μm) consisted of approximately 65% ions/OM/EC and 20% metal oxides.Pb, Zn, and Cu showed crustal enrichment factors (CEF_Si) > 100 for all particle sizes indicating strong anthropogenic influence. The Zn source was coal burning rather than traffic emissions. Doubled concentrations in winter were likely caused by coal combustion (Pb) and biomass burning (K), but also by a lower mixing layer height. Air masses from the East caused higher Pb and K concentrations. The origin of air masses had almost no influence on Cu, Cr, Fe, Mn, Zn and Ca, Si, Ti, indicating local sources such as traffic and heating. Possible actions against particle emissions are discussed.     

Effects of spinosad and Bacillus thuringiensis israelensis on a natural population of Daphnia pulex in field microcosms

Spinosad, a candidate biological larvicide for mosquito control, was evaluated for its effects on a field population of Daphnia pulex, using Bacillus thuringiensis serovar israelensis (Bti) as a reference larvicide. Microcosms (125L enclosures) were placed in a shallow temporary oligohaline marsh where D. pulex was present. Three concentrations of spinosad (8, 17 and 33 microg L(-1)) and two concentrations of Bti (0.16 and 0.50 microL L(-1)) were applied (5 replicates per concentration, including the controls). Effects of larvicides on D. pulex were evaluated after 2, 4, 7, 14 and 21d of exposure, through measurements of abundance and individual size. Dissipation of spinosad from the water phase was rapid. Four days after treatment, residue concentration represented 11.8%, 3.9% and 12.7% of the initial exposure level for the nominal concentrations of 8, 17 and 33 microg L(-1), respectively. Spinosyns A and D dissipated at similar rates. Analysis of abundance and size structure of the D. pulex population showed an impact of spinosad. Both survival and size structure were affected. However, at the lowest concentration (8 microg L(-1)), population recovered after the first week. In microcosms treated with Bti, the abundance of D. pulex was not affected but the size structure of the population changed after 21d. As compared to laboratory tests, the use of in situ microcosms improved the environmental risk assessment of larvicides, taking into account the influence of environmental factors (e.g., temperature, light, salinity) and intrinsic capacity of recovery of D. pulex under field conditions.     

Metal accumulation in mosses across national boundaries: uncovering and ranking causes of spatial variation

This study aimed at cross-border mapping metal loads in mosses in eight European countries in 1990, 1995, and 2000 and at investigating confounding factors. Geostatistics was used for mapping, indicating high local variances but clear spatial autocorrelations. Inference statistics identified differences of metal concentrations in mosses on both sides of the national borders. However, geostatistical analyses did not ascertain discontinuities of metal concentrations in mosses at national borders due to sample analysis in different laboratories applying a range of analytical techniques. Applying Classification and Regression Trees (CART) to the German moss data as an example, the local variation in metal concentrations in mosses were proved to depend mostly on different moss species, potential local emission sources, canopy drip and precipitation.     

Toxicity assessment of textile effluents treated by advanced oxidative process (UV/TiO2 and UV/TiO2/H2O2) in the species Artemia salina L.

Textile industry wastes raise a great concern due to their strong coloration and toxicity. The objective of the present work was to characterize the degradation and mineralization of textile effluents by advanced oxidative processes using either TiO₂ or TiO₂/H₂O₂ and to monitor the toxicity of the products formed during 6-h irradiation in relation to that of the in natura effluent. The results demonstrated that the TiO₂/H₂O₂ association was more efficient in the mineralization of textile effluents than TiO₂, with high mineralized ion concentrations (NH ₄ ⁺ , NO ₃ ^? , and SO ₄ ^2? ) and significantly decreased organic matter ratios (represented by the chemical oxygen demand and total organic carbon). The toxicity of the degradation products after 4-h irradiation to Artemia salina L. was not significant (below 10 %). However, the TiO₂/H₂O₂ association produced more toxicity under irradiation than the TiO₂ system, which was attributed to the increased presence of oxidants in the first group. Comparatively, the photogenerated products of both TiO₂ and the TiO₂/H₂O₂ association were less toxic than the in natura effluent.     

Escape Dynamics in Office Buildings: Using Molecular Dynamics to Quantify the Impact of Certain Aspects of Human Behavior During Emergency Evacuation

Emergency evacuation of office buildings, in the event of a life-threatening situation such as a fire incident, is a function of various factors ranging from architectural to socio-behavioral ones. We show how individual-based modeling approaches such as molecular dynamics can be coupled with behavioral responses in panic situations, in order to quantify in a systematic way the impact of human familiarity to the space, during emergency evacuation. The ultimate goal is to identify certain crucial design features that can help in engineering better evacuation plans.     

Hare or Tortoise? Trade-offs in Recovering Sustainable Bioeconomic Systems

In this paper, we develop a framework for (a) the study of sustainability of dynamic bioeconomic systems and (b) the definition of recovery paths from unsustainable situations. We assume that the system follows a sustainable trajectory if it evolves over time within a set of multidimensional constraints. We use the mathematical concept of viability to characterize sustainability. Recovery paths are studied with regards to their duration and their acceptability. This general framework is applied to the issue of recovering sustainable fisheries. We define sustainability in a fishery as the requirement that a set of economic, ecological, and social constraints is satisfied at all times. Recovery paths are characterized by the time required to obtain sustainable exploitation conditions in the fishery and by the acceptable recovery costs for fishermen. In particular, we identify the recovery path which minimizes the time of crisis under a minimum transition profit constraint. We then describe the trade-off between speed and accepted costs of recovery paths, by comparing “Hare”-like high-speed–high-cost strategies to “Tortoise”-like low-speed–low-cost strategies. We illustrate our results by means of a numerical analysis of the Bay of Biscay Nephrops fishery.