The value of Seasonal Correction Factors in assessing the health risk from domestic radon: a case study in Northamptonshire, UK

Following an intensive survey of domestic radon levels in the United Kingdom (UK), the former National Radiological Protection Board (NRPB), now the Radiation Protection Division of the Health Protection Agency (HPA-RPD), established a measurement protocol and promulgated Seasonal Correction Factors applicable to the country as a whole. Radon levels in the domestic built environment are assumed to vary systematically and repeatably during the year, being generally higher in winter. The Seasonal Correction Factors therefore comprise a series of numerical multipliers, which convert a 1-month or 3-month radon concentration measurement, commencing in any month of the year, to an effective annual mean radon concentration. In a recent project undertaken to assess the utility of short-term exposures in quantifying domestic radon levels, a comparative assessment of a number of integrating detector types was undertaken, with radon levels in 34 houses on common geology monitored over a 12-month period using dose-integrating track-etch detectors exposed in pairs (one upstairs, one downstairs) at 1-month and 3-month resolution. Seasonal variability of radon concentrations departed significantly from that expected on the basis of the HPA-RPD Seasonal Correction Factor set, with year-end discontinuities at both 1-month and 3-month measurement resolutions. Following this study, monitoring with electrets was continued in four properties, with weekly radon concentration data now available for a total duration in excess of three and a half years. Analysis of this data has permitted the derivation of reliable local Seasonal Correction Factors. Overall, these are significantly lower than those recommended by HPA-RPD, but are comparable with other results from the UK and from abroad, particularly those that recognise geological diversity and are consequently prepared on a regional rather than a national basis. This finding calls into question the validity of using nationally aggregated Seasonal Correction Factors, especially for shorter exposures, and the universal applicability of these corrections is discussed in detail.     

Impact of dredging in a shallow coastal lagoon: Microtox Basic Solid-Phase Test, trace metals and Corophium bioassay

The aim of this work was to measure survival of the amphipod Corophium insidiosum and luminescence inhibition in the marine bacterium Vibrio fisheri on surface sediment samples collected from a shallow coastal lagoon (Pialassa Baiona, northern Adriatic Italian coast) before execution of dredging operations to deepen the main inner channel of the lagoon and restore the water circulation. Trace metal (Cd, Cu, Cr, Hg, Ni, Pb) concentrations, grain size and organic carbon matter content as loss of ignition were also measured. Toxicity testing with V. fisheri was carried out according to the Microtox Basic Solid-Phase Test (BSPT) protocol. The preliminary outcomes of this work show that: (a) the investigated area can be categorised as moderately degraded; (b) there is no evident spatial pattern in sediment toxicity and trace metal concentrations; (c) Microtox responses are not biased by sediment characteristics such as silt, clay and organic matter content.     

Cladocerans under conditions of small river damming by man and beavers

In beaver ponds, the species diversity, abundance, biomass, and production of cladocerans and the amount of food consumed by them have increased and the composition of dominant species has changed as compared to those in the stretches of small rivers with running water or dammed by man. The stimulating effect of water from a beaver pond has been confirmed in laboratory experiments. The average number of juvenile Ceriodaphnia affinis produced by one female was considerably greater in this water than in the water from flowing and dammed (by man) river stretches.     

Specific features of phenetic structure of the terrestrial snail <Emphasis Type="Italic">Cepaea vindobonensis</Emphasis> (Pulmonata; Helicidae) in urbanized and natural populations

The phenetic structure of natural and urbanized populations of the terrestrial snail Cepaea vindobonensis has been studied with respect to polymorphism in the shell-band color and pattern. It is noted that C. vindobonensis snails populating different artificial habitats in the city of Nikolaev and its suburbs are characterized by a higher level of both intra-and interpopulation diversity with respect to the type of this polymorphism. In addition, urban populations show a very wide range of variation in the frequencies of particular morphs or their groups. Conversely, natural populations are characterized by a more uniform frequency structure with respect to polymorphism of the shell banding pattern.     

Transport and fate of mercury under different hydrologic regimes in polluted stream in mining area

Seepage from Hg mine wastes and calcines contains high concentrations of mercury (Hg). Hg pollution is a major environmental problem in areas with abandoned mercury mines and retorting units. This study evaluates factors, especially the hydrological and sedimentary variables, governing temporal and spatial variation in levels and state of mercury in streams impacted by Hg contaminated runo . Samples were taken during di erent flow regimes in theWanshan Hg mining area in Guizhou Province, China. In its headwaters the sampled streams/rivers pass by several mine wastes and calcines with high concentration of Hg. Seepage causes serious Hg contamination to the downstream area. Concentrations of Hg in water samples showed significant seasonal variations. Periods of higher flow showed high concentrations of total Hg (THg) in water due to more particles being re-suspended and transported. The concentrations of major anions (e.g., Cl??, F??, NO3?? and SO4 2??) were lower during higher flow due to dilution. Due to both sedimentation of particles and dilution from tributaries the concentration of THg decreased from 2100 ng/L to background levels (< 50 ng/L) within 10 km distance downstream. Sedimentation is the main reason for the fast decrease of the concentration, it accounts for 69% and 60% for higher flow and lower flow regimes respectively in the upper part of the stream. Speciation calculation of the dissolved Hg fraction (DHg) (using Visual MINTEQ) showed that Hg(OH)2 associated with dissolved organic matter is the main form of Hg in dissolved phase in surface waters in Wanshan (over 95%).     

A new Dasypodini armadillo (Xenarthra: Cingulata) from San Gregorio Formation,Pliocene of Venezuela: affinities and biogeographic interpretations

We describe Pliodasypus vergelianus gen. et sp. nov., a Dasypodini armadillo from the middle Pliocene of Venezuela (Vergel Member, San Gregorio Formation). Although scarce, the remains are remarkable because of their geochronologic proximity to the main phase of Great American Biotic Interchange (GABI). The cladistic analysis conducted reveals that Pliodasypus groups with Dasypus and both are sister taxa of Propraopus, whereas Anadasypus is at a basal position. With respect to the records of tribe Dasypodini, after its oldest representative (Anadasypus, middle and late Miocene), the chronologically subsequent form is Pl. vergelianus (middle Pliocene), followed by Dasypus bellus in higher northern latitudes (late Pliocene), and then by widespread occurrences in the Pleistocene of North America (D. bellus) and South America (Propraopus, Dasypus punctatus, and Dasypus novemcinctus). Thus, we infer that Dasypus differentiated in the late Pliocene at low latitudes in the northern South America. It leads to two alternative hypotheses of dispersal: (a) some early Dasypus remained cryptically in South America until the Pleistocene, whereas others dispersed to North America between 2.2 and 2.7 Ma, or (b) they dispersed to North America subsequently to the emersion of the Panamanian isthmus and D. bellus differentiated there; later, during the Pleistocene, D. bellus entered South America and experienced speciation. The same process of re-ingression has been proposed to other xenarthrans, breaking with the traditional assumption that the GABI was unidirectional.     

Juvenile morphology in baleen whale phylogeny

Phylogenetic reconstructions are sensitive to the influence of ontogeny on morphology. Here, we use foetal/neonatal specimens of known species of living baleen whales (Cetacea: Mysticeti) to show how juvenile morphology of extant species affects phylogenetic placement of the species. In one clade (sei whale, Balaenopteridae), the juvenile is distant from the usual phylogenetic position of adults, but in the other clade (pygmy right whale, Cetotheriidae), the juvenile is close to the adult. Different heterochronic processes at work in the studied species have different influences on juvenile morphology and on phylogenetic placement. This study helps to understand the relationship between evolutionary processes and phylogenetic patterns in baleen whale evolution and, more in general, between phylogeny and ontogeny; likewise, this study provides a proxy how to interpret the phylogeny when fossils that are immature individuals are included. Juvenile individuals in the peramorphic acceleration clades would produce misleading phylogenies, whereas juvenile individuals in the paedomorphic neoteny clades should still provide reliable phylogenetic signals.     

Direct evidence of trophic interactions among apex predators in the Late Triassic of western North America

Hypotheses of feeding behaviors and community structure are testable with rare direct evidence of trophic interactions in the fossil record (e.g., bite marks). We present evidence of four predation, scavenging, and/or interspecific fighting events involving two large paracrocodylomorphs (=‘rauisuchians’) from the Upper Triassic Chinle Formation (～220–210 Ma). The larger femur preserves a rare history of interactions with multiple actors prior to and after death of this ～8–9-m individual. A large embedded tooth crown and punctures, all of which display reaction tissue formed through healing, record evidence of a failed attack on this individual. The second paracrocodylomorph femur exhibits four unhealed bite marks, indicating the animal either did not survive the attack or was scavenged soon after death. The combination of character states observed (e.g., morphology of the embedded tooth, ‘D’-shaped punctures, evidence of bicarination of the marking teeth, spacing of potentially serial marks) indicates that large phytosaurs were actors in both cases. Our analysis of these specimens demonstrates phytosaurs targeted large paracrocodylomorphs in these Late Triassic ecosystems. Previous distinctions between ‘aquatic’ and ‘terrestrial’ Late Triassic trophic structures were overly simplistic and built upon mistaken paleoecological assumptions; we show they were intimately connected at the highest trophic levels. Our data also support that size cannot be the sole factor in determining trophic status. Furthermore, these marks provide an opportunity to start exploring the seemingly unbalanced terrestrial ecosystems from the Late Triassic of North America, in which large carnivores far outnumber herbivores in terms of both abundance and diversity.     

Trail laying during tandem-running recruitment in the ant Temnothorax albipennis

Tandem running is a recruitment strategy whereby one ant leads a single naïve nest mate to a resource. While tandem running progresses towards the goal, the leader ant and the follower ant maintain contact mainly by tactile signals. In this paper, we investigated whether they also deposit chemical signals on the ground during tandem running. We filmed tandem-running ants and analysed the position of the gasters of leaders and followers. Our results show that leader ants are more likely to press their gasters down to the substrate compared to follower ants, single ants and transporter ants. Forward tandem-run leaders (those moving towards a new nest site) performed such trail-marking procedures three times more often than reverse tandem leaders (those moving towards an old nest site). That leader ants marked the trails more often during forward tandem runs may suggest that it is more important to maintain the bond with the follower ant on forward tandem runs than on reverse tandem runs. Marked trails on the ground may serve as a safety line that improves both the efficiency of tandem runs and their completion rates.     

The antennal sensilla of Melipona quadrifasciata (Hymenoptera: Apidae: Meliponini): a study of different sexes and castes

The sensilla of insects are integumental units that play a role as sensory structures and are crucial for the perception of stimuli and for communication. In this study, we compared the antennal sensilla of females (workers and queens), males (haploid (n) and diploid (2n)), and queen-like males (QLMs, resulting from 2n males after juvenile hormone (JH) treatment) in the stingless bee Melipona quadrifasciata. Images of the dorsal antenna surfaces were acquired using a scanning electron microscope. As reported for other hymenopterans, this species exhibits a heterogeneous sensillar distribution along the antennae. Thirteen different types of sensilla were found in the antennae of M. quadrifasciata: trichodea (subtypes I to VI), chaetica (subtypes I and II), placodea, basiconica, ampullacea, coeloconica, and coelocapitula. Sensilla trichodea I were the most abundant, followed by sensilla placodea, which might function in olfactory perception. Sensilla basiconica, sensilla chaetica I, sensilla coeloconica, and sensilla ampullacea were found exclusively in females. In terms of the composition and size of the sensilla, the antennae of QLMs most closely resemble those of the 2n male, although QLMs exhibit a queen phenotype. This study represents the first comparative analysis of the antennal sensilla of M. quadrifasciata. The differences found in the type and amount of sensilla between the castes and sexes are discussed based on the presumed sensillary functions.