Tracing the sources of gaseous components (<Superscript>222</Superscript>Rn,CO<Subscript>2</Subscript> and its carbon isotopes) in soil air under a cool-deciduous stand in Sapporo,Japan

Radon (²²²Rn) and carbon dioxide were monitored simultaneously in soil air under a cool-temperate deciduous stand on the campus of Hokkaido University, Sapporo, Japan. Both ²²²Rn and CO₂ concentrations in soil air varied with atmospheric (soil) temperature in three seasons, except for winter when the temperature in soil air remained constant at 2–3°C at depth of 80 cm. In winter, the gaseous components were influenced by low-pressure region passing through the observation site when the ground surface was covered with snow of ~1 m thickness. Carbon isotopic analyses of CO₂ suggested that CO₂ in soil air may result from mixing of atmospheric air and soil components of different origins, i.e. CO₂ from contemporary soil organic matter and old carbon from deeper source, to varying degrees, depending on seasonal meteorological and thus biological conditions.     

Geochemical and microbial effects on the mobilization of arsenic in mine tailing soils

Arsenic (As) contamination has become a serious environmental problem in many countries. We have performed batch-type leaching experiments on mine tailing soils collected from three abandoned mine areas in South Korea with the objective of evaluating the effect of indigenous bacterial activity on As mobilization. The analysis of physicochemical properties and mineralogical compositions of the samples indicated that the secondary minerals or phases formed as a result of the oxidation or alteration of primary minerals were associated with the labile and bioleachable fractions of As. Compared to simulated abiotic processes using sterilization, the indigenous bacteria activated using a carbon source were able to enhance the dissolution of As under both aerobic and anaerobic conditions. The bacterial dissolution of iron (Fe) and manganese (Mn) was found to occur simultaneously with the dissolution of As, suggesting that the main bacterial mechanism was via the dissimilatory reduction of Fe(III), Mn(IV), and As(V). An anaerobic environment was more favorable for the prominent dissolution of As in the tailing soils. These results indicate that the mobilization of As can be enhanced in the oxygen-depleted part of the tailing dump, particularly with the infiltration of organic substrates. The difference in the degree of As lixiviation between the three tailing soils was found to be related to the bioavailability of As as well as the original biomass in the tailing soils.     

Effect of temperature on seawater desalination-water quality analyses for desalinated seawater for its use as drinking and irrigation water

The effect of feed seawater temperature on the quality of product water in a reverse osmosis process was investigated using typical seawater at Urla Bay, Izmir region, Turkey. The tests were carried out at different feed seawater temperatures (11–23°C) using two RO modules with one membrane element each. A number of variables, including pH, conductivity, total dissolved solids, salinity, rejection percentage of a number of ions (Na⁺, K⁺, Ca²⁺, Mg²⁺, Cl⁻, HCO₃ ⁻, and SO₄ ²⁻), and the levels of boron and turbidities in collected permeates, were measured. The suitability of these permeates as irrigation and drinking water was checked by comparison with water quality standards.     

Anthropogenic influence on surface water quality of the Nhue and Day sub-river systems in Vietnam

In order to investigate the temporal and spatial variations of 14 physical and chemical surface water parameters in the Nhue and Day sub-river systems of Vietnam, surface water samples were taken from 43 sampling sites during the dry and rainy seasons in 2007. The results were statistically examined by Mann–Whitney U-test and hierarchical cluster analysis. The results show that water quality of the Day River was significantly improved during the rainy season while this was not the case of the Nhue River. However, the river water did not meet the Vietnamese surface water quality standards for dissolved oxygen (DO), biological oxygen demand (BOD₅), chemical oxygen demand (COD), nutrients, total coliform, and fecal coliform. This implies that the health of local communities using untreated river water for drinking purposes as well as irrigation of vegetables may be at risk. Forty-three sampling sites were grouped into four main clusters on the basis of water quality characteristics with particular reference to geographic location and land use and revealed the contamination levels from anthropogenic sources.     

Refueling while flying: foraging bats combust food rapidly and directly to power flight

Flying vertebrates, such as bats, face exceptionally high energy costs during active flapping flight. Once airborne, energy turnover may exceed basal metabolic rate by a factor of up to 15. Here, we asked whether fuel that powers flight originates from exogenous (dietary nutrients), endogenous sources (mostly body lipids or glycogen), or a combination of both. Since most insectivorous bats fly continuously over relatively long time periods during foraging, we assumed that slowly mobilized glycogen, although suitable for supporting brief sallying flights, is inadequate to power aerial insect-hunting of bats. We hypothesized that the insect-feeding Noctilio albiventris rapidly mobilizes and combusts nutrients from insects it has just eaten instead of utilizing endogenous lipids. We used the stable carbon isotope ratio in the bats' exhaled breath (delta13C(brth)) to assess the origin of metabolized substrates of resting and flying N. albiventris in two nutritional conditions: fasted and recently fed. The breath of fasted resting bats was depleted in 13C in relation to their insect diet (delta13C(diet)), indicating the combustion of 13C depleted body lipids. In contrast to this, delta13C(brth) of bats that had recently fed closely matched delta13C(diet) in both resting and flying bats, suggesting a quick mobilization of ingested nutrients for metabolism. In contrast to most non-volant mammals, bats have evolved the ability to fuel their high energy expenditure rates through the rapid combustion of exogenous nutrients, enabling them to conquer the nocturnal niche of aerial insectivory.     

Increasing polybrominated diphenyl ether (PBDE) contamination in sediment cores from the inner Clyde Estuary,UK

The concentrations of 16 polybrominated diphenyl ether (PBDE) congeners in six short sediment cores from the Clyde Estuary were determined by gas-chromatography mass-spectrometry. Total PBDE concentrations ranged from 1 to 2,645 μg/kg and the average concentration was 287 μg/kg. BDE-209 was the main congener and varied from 1 to 2,337 μg/kg. Elevated total PBDE concentrations were observed close to the sediment surface in the uppermost 10 cm of four of the six sediment cores. Comparison of the down core PBDE profiles revealed that the increase was driven by the accumulation of deca-BDE. Although the deca-BDE mix was dominant, the presence of lower molecular weight congeners BDE-47, BDE-99, BDE-183 and BDE-153 at most sediment intervals suggested additional sources of penta-BDE and octa-BDE pollution. Changing PBDE source input was the major factor in influencing the proportion of nona-brominated congeners, although other explanations such as post burial photo-debromination of BDE-209 cannot be entirely discounted. A clear cascading to lower hepta-, hexa-, and penta-homologues was not found. The increase in total PBDE concentrations and particularly the deca-BDE may possibly be ascribed to the use and subsequent disposal of electrical appliances such as televisions and computers. In the Clyde sediments, the proportion of nona-brominated congeners was higher than that reported for commercial mixtures. This might be due to changing sources of PBDEs or post burial photo-debromination of BDE-209.     

Conditional sex allocation in the Red Mason bee, Osmia rufa

Trivers' and Willard's hypothesis that natural selection favors sex allocation in relation to maternal condition assumes iteropary. Though this assumption is not met in most solitary Aculeata, the reproductive life span of semelparous females may be divided into discrete successive cycles by the risk of open-cell parasitism. Females can avoid losing their investment to parasites attacking the open cell only by limiting the provision time for each cell. The restriction of time available for the investment in a single progeny irrespective of the condition of the female leads to de facto iteropary. Moreover, in Hymenoptera, there are no costs for sex allocation due to the haplodiploid mode of sex determination. In sexually size dimorphic species, females in poor condition are predicted to invest in the smaller sex and vice versa. The resulting prediction of a conditional sex allocation in solitary Aculeata was tested in the Red Mason bee, Osmia rufa (Osmia bicornis), a stem or hole-nesting, polylectic, univoltine megachilid bee. Body size is a key component of condition in females of nest-constructing solitary bees. Large females collect the same amount of pollen and nectar in a shorter time than small ones and should suffer less from parasitism. We found that small females dealt with their handicap of a low provisioning performance by shifting the sex ratio toward sons (the smaller sex) and by reducing the body size of daughters. Large females, however, shifted their offspring sex ratio toward daughters, the sex that depends more on body size in its reproductive value. The sex ratio in the population met the expected Fisherian sex ratio. Although females allocated their investment in the sexes according to their body mass, the population-level investment was balanced.     

Exaggerated orientation scatter of nocturnal passerine migrants close to breeding grounds: comparisons between seasons and latitudes

Using tracking radars, we investigated the variability of flight directions of long-distance nocturnal passerine migrants across seasons (spring versus autumn migration) and sites at the southern (56° N) and northern (68° N) ends of the Scandinavian Peninsula (Lund versus Abisko). Whilst most migrants at Lund are on passage to and from breeding sites in Fennoscandia, the majority of the migrants at Abisko are close to their breeding sites, and migration at Abisko thus to a large degree reflects initial departure from breeding sites (autumn) or final approach to breeding destinations (spring). The radar data were used to test predictions about differences in orientation and wind drift effects between adult and juvenile birds (a large proportion of autumn migrants consists of juvenile birds on their first journey), between situations far away from or near the goals and between different phases of migration (initial departure, en route passage, final approach to goal). The concentrations (both total and within-night concentrations) of flight directions differed significantly between seasons as well as sites, with the highest concentration at Lund in spring (mean vector length of track directions, r = 0.79) and lowest at Abisko during spring (r = 0.35). Partial wind drift and partial compensation were recorded at Lund, with a similar effect size in spring and autumn, whilst possible wind drift effects at Abisko were obscured by the large directional scatter at this site. The results from Lund support the prediction that the high proportion of juveniles in autumn contributes to increase the directional scatter during this season, whilst there was no support for predictions of differential wind drift effects between seasons and situations with different goal distances. The most striking and surprising result was the exceedingly large scatter of flight directions at Abisko, particularly in spring. We suggest that such an exaggerated scatter may be associated with final approach orientation, where migrants reach their specific goals from all various directions by final navigation within a more wide-ranging goal region. The larger scatter of autumn flight directions at Abisko compared to Lund may be due to exploratory flights in variable directions being more common at initial departure from breeding sites than later during migratory passage. These surprising results highlight the importance of studying and analysing orientation during final approach to (and initial departure from) migratory goals for understanding the orientation systems of migratory birds.     

Polyandry, multiple mating, and female fitness in a water strider Aquarius paludum

Contrary to Bateman’s principle, polyandry appears to be a common female mating strategy. Several hypotheses have been proposed to explain the evolution of polyandry. It is assumed that females gain either material or genetic benefits from multiple matings, or that they are coerced into mating by males. In water striders, mating is generally assumed to be costly to females, and they are thought to mate for reasons of convenience, adjusting their resistance to mating according to male harassment. Here, we tested the effect of number of matings (with the same male) and number of partners on female fitness in a water strider Aquarius paludum. In the first experiment, we regulated the time females spent with a male and found that females’ egg production increased with multiple matings up to a point. The result supports the existence of an optimal female mating frequency. In the second experiment, we tested how polyandry affects the number of eggs laid and egg hatching success. We conducted three different trials: females mated four times with either a single male, two different males, or with four different males. Females that mated with four different males laid the lowest number of eggs and had the lowest egg hatching success, suggesting that polyandry reduces females’ egg production and egg hatching success in A. paludum. We conclude that A. paludum females probably gain material benefits from mating but no genetic benefits were found in this study.