Sources of organochlorine pesticides in air in an urban Mediterranean environment: volatilisation from soil

Organochlorine pesticide (OCP) cycling was studied in the area of Banja Luka, Bosnia and Herzegovina, over 3 days in summer with high temporal (4 h-means) and spatial (3 sites distanced 3-6 km) resolutions. Elevated levels of DDX compounds (i.e. o,p'- and p,p'-isomers of DDT, DDE and DDD, 44-74 pg m(-3) at the urban sites and 27 pg m(-3) as a background level), HCH (α-, β- and γ-isomers, 52-70 vs. 147 pg m(-3)), HCB (34-48 vs. <0.1 pg m(-3)) and pentachlorobenzene (6.8-9.9 vs. 6.0 pg m(-3)) were found. The variation of OCP levels at the two urban sites was not in phase, except for most DDX compounds. This was related to background levels, which for HCH were higher than in the urban area. Vertical profiles between samples collected from 1.1 and 2.3 m (part of the time 0.6 and 2.3 m) above a soil, which was only moderately contaminated by OCPs (0.12 ng g(-1) HCH, 0.11 ng g(-1) DDX, 0.44 ng g(-1) HCB) were analysed. Volatilisation from the ground caused negative vertical concentration gradients of HCH isomers (day and night), but not for HCB (except for 1 day-time sample) and DDX compounds (except p,p'-DDD, day-time, sporadically). The concentration in air and the vertical concentration gradient of the HCH isomers varied with air temperature (day-time maxima), while the variation of the HCB concentration was inversely related to air temperature and was determined by mixing (night-time maxima). α- and β-HCH were volatilised from soil throughout the three days, even during periods of cooling. Fugacity calculations, based on the absorption in soil organic matter as the process determining retention in soil, underestimated the volatilisation of β-HCH and p,p'-DDD. It is concluded that the representativeness of point measurements of OCPs in urban areas is limited by the spatial variability of soil contamination.     

Exotic species,Experienced, and Idealized Nature

This paper is an answer to the Caplat and Coutts forum about our previous paper “The need for flexibility in conservation practices: exotic species as an example”. We precise here why we proposed to consider exotic species as well as indigenous species in the reconnection framework in human-modified environments. One argument is that consistent and understandable arguments must be used in the communication from scientists to the public, in order not to decrease the gap between science and society.     

A prehistoric tsunami induced long-lasting ecosystem changes on a semi-arid tropical island—the case of Boka Bartol (Bonaire, Leeward Antilles)

The Caribbean is highly vulnerable to coastal hazards. Based on their short recurrence intervals over the intra-American seas, high-category tropical cyclones and their associated effects of elevated storm surge, heavy wave impacts, mudslides and floods represent the most serious threat. Given the abundance of historical accounts and trigger mechanisms (strike-slip motion and oblique collision at the northern and southern Caribbean plate boundaries, submarine and coastal landslides, volcanism), tsunamis must be considered as well. This paper presents interdisciplinary multi-proxy investigations of sediment cores (grain size distribution, carbonate content, loss-on-ignition, magnetic susceptibility, microfauna, macrofauna) from Washington-Slagbaai National Park, NW Bonaire (Leeward Antilles). No historical tsunami is recorded for this island. However, an allochthonous marine layer found in all cores at Boka Bartol reveals several sedimentary criteria typically linked with tsunami deposits. Calibrated ¹⁴C data from these cores point to a palaeotsunami with a maximum age of 3,300 years. Alternative explanations for the creation of this layer, such as inland flooding during tropical cyclones, cannot entirely be ruled out, though in recent times even the strongest of these events on Bonaire did not deposit significant amounts of sediment onshore. The setting of Boka Bartol changed from an open mangrove-fringed embayment into a poly- to hyperhaline lagoon due to the establishment or closure of a barrier of coral rubble during or subsequent to the inferred event. The timing of the event is supported by further sedimentary evidence from other lagoonal and alluvial archives on Bonaire.     

The parthenogenetic Marmorkrebs (marbled crayfish) produces genetically uniform offspring

Genetically identical animals are very much in demand as laboratory objects because they allow conclusions about environmental and epigenetic effects on development, structures, and behavior. Furthermore, questions about the relative fitness of various genotypes can be addressed. However, genetically identical animals are relatively rare, in particular, organisms that combine a high reproduction rate and a complex organization. Based on its exclusively parthenogenetic reproduction mode, it has been suggested that the Marmorkrebs (Crustacea, Decapoda, Astacida), a recently discovered crayfish, is an excellent candidate for research addressing the aforementioned questions. However, until now, a study using molecular markers that clearly proves the genetic uniformity of the offspring has been lacking. Here, with this first molecular study, we show that this crayfish indeed produces genetically uniform clones. We tested this with 19 related individuals of various generations of a Marmorkrebs population by means of six different microsatellite markers. We found that all examined specimens were identical in their allelic composition. Furthermore, half of the analyzed loci were heterozygous. These results and the absence of meioses in previous histological studies of the ovaries lead us to conclude the Marmorkrebs propagates apomictically. Thus, a genetically uniform organism with complex morphology, development, and behavior is now available for various laboratory studies.     

Interception of dry and wet deposited radionuclides by vegetation

Interception of dry and wet deposited radionuclides by vegetation is a key process in radioecological models that assess ingestion doses to the population following releases of radionuclides to the atmosphere. Radionuclides may be deposited during precipitation or as dry particles. Interception of wet deposited radionuclides is the result of a complex interaction of the vegetative development of the plant canopy, the amount of rainfall, and the chemical form of radionuclides. For the interception of dry deposits, particle size is a key parameter; interception is more effective for small particles and reactive gases. Due to the dependence on plant development, interception of both dry and wet deposits is subject to pronounced seasonality.     

Improving the adsorption capacity and solid structure of natural volcanic soil using a foaming-sintering process based on recycled polyethylene terephthalate (PET).

The volcanic soils of southern Chile have demonstrated a high capacity to adsorb environmental pollutants, but for an industrial application, a stable solid material is necessary. The objective of this work was to produce a stable ceramic material through a process involving volcanic soil-polyurethane foam produced with recycled polyethylene terephthalate (PET)-polyols, and further thermal treatment. The selected foam formulation with 35.4% volcanic soil (< 63 microm) seems to be the most suitable for thermal treatment, with temperature steps at 700, 850, 1000 and 1200 degrees C. The porous ceramic material obtained has a stable solid form and an improved chlorophenols adsorption capacity (comparable to natural zeolites) that makes it suitable for advanced wastewater treatment and landfill leachate depuration.     

Quantification of sources of PCBs to the atmosphere in urban areas: A comparison of cities in North America, Western Europe and former Yugoslavia

We present estimated emission source strengths of seven polychlorinated biphenyl (PCB) congeners for Banja Luka, a city that was affected by the civil war in Bosnia and Hercegovina (former Yugoslavia) in the 1990s. These emission estimates are compared to PCB emission rates estimated for the cities of Zurich, Switzerland, and Chicago, USA using an approach that combines multimedia mass balance modeling and measurement data. Our modeled per-capita emission estimates for Banja Luka are lower by a factor of ten than those for Zurich and Chicago, which are similar. This indicates that the sources of PCB emissions in Banja Luka are likely to be weaker than in the Western European and North American cities which show relatively high PCB emissions. Our emission rates from the three cities agree within a factor of ten with emission estimates from a global PCB emission inventory derived from production and usage estimates and emission factors.