Nest-seeking rock ants (Temnothorax albipennis) trade off sediment packing density and structural integrity for ease of cavity excavation

We investigated excavation and nest site choice across sediment-filled cavities in the ant Temnothorax albipennis. Colonies were presented with sediment-filled cavities, covering a spectrum from ones that should be quick to excavate but will form a weak enclosing wall to those that should be slow to excavate but form a strong wall. Overall, colonies only showed a significant preference for cavities that were fastest to excavate over those that were slowest. The speed of decision making and moving appears paramount over the suitability of the sediment for forming an enclosing wall. The mechanism behind the choice is the differential between the rates at which alternatives are excavated and accumulate ants. The rates for a particular type of cavity were unaffected by the type with which it was paired. This suggests that there is no significant competition between sites during the decision-making process. Certain colonies were able consistently to discriminate across more closely matched alternatives. These colonies required a greater number of ants to be present and took longer before beginning to move. A race is run between alternatives to become habitable but the process may be tuned across colonies such that it may run for longer and an incorrect or split decision is less likely.     

Assessing radiation impact at a protected coastal sand dune site: an intercomparison of models for estimating the radiological exposure of non-human biota

This paper presents the application of three publicly available biota dose assessment models (the ERICA Tool, R&D128/SP1a and RESRAD-BIOTA) to an assessment of the Drigg coastal sand dunes. Using measured ⁹⁰Sr, ⁹⁹Tc, ¹³⁷Cs, ²³⁸Pu, ^239+240Pu and ²⁴¹Am activity concentrations in sand dune soil, activity concentration and dose rate predictions are made for a range of organisms including amphibians, birds, invertebrates, mammals, reptiles, plants and fungi. Predicted biota activity concentrations are compared to measured data where available. The main source of variability in the model predictions is the transfer parameters used and it is concluded that developing the available transfer databases should be a focus of future research effort. The value of taking an informed user approach to investigate the way in which models may be expected to be applied in practice is highlighted and a strategy for the future development of intercomparison exercises is presented.     

Synthesis of a highly recoverable 3D MnO2/rGO hybrid aerogel for efficient adsorptive separation of pharmaceutical residue

Water contamination by non-steroidal anti-inflammatory drugs, such as acetaminophen, is an emerging ecological concern. In this study, a new three-dimensional manganese dioxide-engrafted reduced graphene oxide (3D MnO₂/rGO) hybrid aerogel was developed for acetaminophen sequestration. The synthesis involved firstly the self-assembly of GO aerogel, followed by thermal reduction and in-situ MnO₂ growth by redox-reaction. The aerogel demonstrated interlinked planes with smooth surfaces deposited with MnO₂ nanospheres and pores of 138.4 – 235.3 µm width. The influences of adsorbent dosage, initial pH, acetaminophen concentration, temperature and contact time were investigated. It was determined that the adsorption of acetaminophen occurred on uniform sorption sites in the aerogel, as suggested by the best fit of data to the Langmuir isotherm, yielding a maximum adsorption capacity of 252.87 mg/g. This highest adsorption performance of the 3D MnO₂/rGO aerogel was attained at a dosage of 0.6 g/L, initial pH of 6.2 and temperature of 40°C. The process kinetics were in-line with the pseudo-first-order and pseudo-second-order kinetics at 10 and 20 – 500 mg/L concentrations, respectively. Thermodynamic assay showed the spontaneity and endothermicity features of the 3D MnO₂/rGO-acetaminophen system. The acetaminophen adsorption mechanisms were mainly hydrogen bonding and pore entrapment. Moreover, the as-synthesised aerogel was effectively regenerated using acetone and re-utilised in four adsorption-desorption cycles. Overall, the results highly recommend the implementation of the 3D MnO₂/rGO hybrid aerogel for purification of wastewater polluted by acetaminophen residue.     

Assessing availability, phytotoxicity and bioaccumulation of lead to ryegrass and millet based on 0.1 mol/L Ca(NO3)2 extraction

This study was conducted to assess availability, phytotoxicity and bioaccumulation of lead （Pb） to ryegrass （Lolium perenne L.） and millet （Echinochloa crusgalli） based on the 0.1 mol/L Ca（NO3）2 extraction. Effect of soil properties on availability, phytotoxicity and bioaccumulation of Pb to the two plants was also evaluated. Five soils with pH values varying from 3.8 to 7.3, organic carbon （OC） contents from 0.7% to 2.4%, and clay contents from 11.6% to 35.6% were selected. Soils were spiked with Pb to achieve a range of concentrations： 250, 500, 1000, 3000 and 5000 mg/kg. Pb availability in the spiked soils was estimated by extracting soil with 0.1 mol/L Ca（NO3）2. The results indicate that plants yield decreased with decreasing soil pH and increased with increasing soil clay and OC content. Negative relationship between available Pb and the relative dry matter growth （RDMG） of the two plants were significantly related. Available Pb used to assess EC20 （20% effective concentration） and EC50 （50% effective concentration） of millet was 119 and 300 mg/kg, respectively. Available Pb used to assess EC20 and EC50 of ryegrass was 63 and 157 mg/kg, respectively. Bioaccumulation, expressed as bioconcentration factors of Pb, was inversely related to soil pH, soil OC and clay content. Strong relationships were found between available lead and uptake by the two plants （P was 0.92 and 0.95 respectively）. In general, 0.1 mol/L Ca（NO3）2 available Pb may be used to assess the availability, phytotoxicity and bioaccumulation of lead to the two plants tested.     

Prenatal findings in generalized amyoplasia

Amyoplasia is a rare, sporadic condition characterized by different degrees of maldevelopment of the skeletal muscles, which are replaced by fibrous and fatty tissue. In this report, we present a case of generalized amyoplasia presenting at 19 weeks' gestation. The most striking finding was the absence of fetal movements, resulting in severe multiple congenital contractures, hydrops, and polyhydramnios. At autopsy, histological examination of the skeletal muscle showed small groups of poorly developed fibres within areas of fat. This report suggests that generalized amyoplasia could be a common cause of severe forms of multiple congenital contractures, but is probably underdiagnosed at post-mortem because of inadequate examination of muscles. Definitive diagnosis is important in determining the risks of recurrence in these cases.     

Arsenic and heavy metal mobility in iron oxide-amended contaminated soils as evaluated by short- and long-term leaching tests

Several iron-bearing additives were evaluated for their effectiveness in the attenuation of arsenic (As) in various contaminated soils. These were selected for their known or potential ability to adsorb As anions, thus changing the speciation of As in a soil system. Three soils with different sources of As contamination were investigated (canal dredgings, coal fly ash deposits, and low-level alkali waste). The amendments used were goethite (alpha-FeOOH), iron grit, iron (II) and (III) sulphates (plus lime), and lime, applied to the soils at a rate of 1% w/w. A series of leachate extraction tests (UKEA, ASTM and modified Dutch column leaching test) were conducted on the equilibrated amended soils. These were used to firstly evaluate the potential of the amendments as immobilising agents, and secondly to compare the short- and long-term durability of their effects. Column tests demonstrated the efficiency of iron oxides over the longer time scale; these treatments significantly reduced concentrations of arsenic in leachates from all treated soils. Amended soils were also observed to contain higher levels of lead (Pb) and cadmium (Cd) in their leachates, signifying that certain Fe-oxides potentially increased heavy metal mobility in treated soils. The conclusions were that whilst Fe-oxides may be used as effective in situ amendments to attenuate As in soils, their effects on other trace elements, such as Pb and Cd, require careful consideration.