Simultaneous measurement of aqueous redox-sensitive elements and their species across the soil-water interface

The redox-sensitive elements, such as iron, manganese, sulfur, phosphorus, and arsenic, shift their speciation every millimeter (mm) across the soil-water interface in the flooded soil environments. Monitoring of element speciation at this high-resolution (HR) within the SWI is still difficult. The key challenge lies in obtaining sufficient porewater samples at specific locations along the soil gradient for downstream analysis. Here with an optimized inductively coupled plasma mass spectrometry (ICP-MS) method and a HR porewater sampler, we demonstrate mm-scale element profiles mapping across the SWI in paddy soils. High-concentrations of iron and manganese (> 10 mg/L) were measured by ICP-MS in an extended dynamic range mode to avoid signal overflow. The iron profile along the SWI generated by the ICP-MS method showed no significant difference (p < 0.05) compared to that measured independently using a colorimetric method. Furthermore, four arsenic (arsenite, arsenate, monomethylarsonic and dimethylarsinic acid), two phosphorus (phosphite and phosphate) and two sulfur (sulfide and sulfate) species were separated in 10 min by ion chromatography -ICP-MS with the NH₄HCO₃ mobile phase. We verified the technique using paddy soils collected from the field, and present the mm-scale profiles of iron, manganese, and arsenic, phosphorus, sulfur species (relative standard deviation < 8%). The technique developed in this study will significantly promote the measurement throughput in limited samples (e.g. 100 μL) collected by HR samplers, which would greatly facilitate redox-sensitive elements biogeochemical cycling in saturated soils.     

Fish Mercury and Surface Water Sulfate Relationships in the Everglades Protection Area

Few published studies present data on relationships between fish mercury and surface or pore water sulfate concentrations, particularly on an ecosystem-wide basis. Resource managers can use these relationships to identify the sulfate conditions that contain fish with health-concerning total mercury (THg) levels and to evaluate the role of sulfate in methyl-mercury (MeHg) production. In this study, we derived relationships between THg in three fish trophic levels (mosquitofish, sunfish, and age-1 largemouth bass) and surface water sulfate from 1998 to 2009 for multiple stations across the Everglades Protection Area (EPA). Results show the relationship between sulfate and fish THg in each fish type is nonlinear and largely skewed, similar to the relationship between MeHg production and sulfate concentration in peatland sediment pore water identified by other researchers. Peak fish THg levels occurred in ~1 to 12 mg/L sulfate conditions. There was significant variability in the fish THg data, and there were several instances of high-fish THg levels in high-sulfate conditions (>30 mg/L). Health-concerning fish THg levels were present in all surface water sulfate conditions; however, most of these levels occurred in 1–20 mg/L sulfate. The data in this study, including recent studies, show consistent and identifiable areas of high- and low-fish THg across the spectrum of surface water sulfate concentration, therefore, applying an ecosystem-wide sulfur strategy may be an effective management approach as it would significantly reduce MeHg risk in the EPA.     

Exploring Land Developer Perspectives on Conservation Subdivision Design and Environmentally Sustainable Land Development

Insight into land developers’ perspectives on alternative residential developments and the barriers they experience in trying to develop them can be crucial in efforts to change environmentally damaging low-density, large-lot, and automobile-dependent residential patterns. Using a semi-structured interview instrument followed by short surveys, I examined the views of 16 developers in Waukesha County, WI, USA, a county that has experienced significant development pressures and widespread implementation of conservation subdivision design. The land developer investigation focused on conservation subdivision design familiarity and implementation, and identified a number of barriers that developers experienced in implementing the design. While the majority of the developers appeared familiar with the design and had experience developing conservation subdivisions, their motivations for developing them varied, as did their on-site conservation practices. The barriers included the lack of land use regulations supporting the design, economic factors, community opposition, and a lack of knowledge about sustainable residential development practices. Strategies to promote more environmentally sustainable residential land development patterns include providing a more supportive institutional environment, enacting different regulations and guidelines for natural resources protection, and offering education on ecologically sound development and planning practices.     

Beyond colour: consistent variation in near infrared and solar reflectivity in sunbirds (Nectariniidae)

The visible spectrum represents a fraction of the sun’s radiation, a large portion of which is within the near infrared (NIR). However, wavelengths outside of the visible spectrum that are reflected by coloured tissues have rarely been considered, despite their potential significance to thermal effects. Here, we report the reflectivity from 300 to 2100 nm of differently coloured feathers. We measured reflectivity across the UV-Vis-NIR spectra of different (a) body parts, (b) colour-producing mechanisms and (c) sexes for 252 individuals of 68 sunbird (family: Nectariniidae) species. Breast plumage was the most reflective and cap plumage the least. Female plumage had greater reflectivity than males. Carotenoid-based colours had the greatest reflectivity, followed by non-iridescent and iridescent melanin-based colours. As ordered arrays of melanin-filled organelles (melanosomes) produce iridescent colours, this suggests that nanostructuring may affect reflectance across the spectrum. Our results indicate that differently coloured feathers consistently vary in their thermal, as well as obvious visual, properties.     

Time management and nectar flow: flower handling and suction feeding in long-proboscid flies (Nemestrinidae: Prosoeca)

A well-developed suction pump in the head represents an important adaptation for nectar-feeding insects, such as Hymenoptera, Lepidoptera and Diptera. This pumping organ creates a pressure gradient along the proboscis, which is responsible for nectar uptake. The extremely elongated proboscis of the genus Prosoeca (Nemestrinidae) evolved as an adaptation to feeding from long, tubular flowers. According to the functional constraint hypothesis, nectar uptake through a disproportionately elongated, straw-like proboscis increases flower handling time and consequently lowers the energy intake rate. Due to the conspicuous length variation of the proboscis of Prosoeca, individuals with longer proboscides are hypothesised to have longer handling times. To test this hypothesis, we used field video analyses of flower-visiting behaviour, detailed examinations of the suction pump morphology and correlations of proboscis length with body length and suction pump dimensions. Using a biomechanical framework described for nectar-feeding Lepidoptera in relation to proboscis length and suction pump musculature, we describe and contrast the system in long-proboscid flies. Flies with longer proboscides spent significantly more time drinking from flowers. In addition, proboscis length and body length showed a positive allometric relationship. Furthermore, adaptations of the suction pump included an allometric relationship between proboscis length and suction pump muscle volume and a combination of two pumping organs. Overall, the study gives detailed insight into the adaptations required for long-proboscid nectar feeding, and comparisons with other nectar-sucking insects allow further considerations of the evolution of the suction pump in insects with sucking mouthparts.     

A preliminary ergonomic assessment of piloting a lifeboat in ice

This paper examines human factors associated with piloting a totally enclosed motor propelled survival craft (TEMPSC or lifeboat) in ice. The first section of the paper describes the use of a usability assessment scale to evaluate the coxswain’s (TEMPSC captain) control panel. The second portion examines environmental conditions (habitability) inside the lifeboat during evacuation. All testing was completed in conditions that were consistent with those that might be experienced by ship or offshore oil and gas crewmembers in the event of abandonment due to an onboard emergency. Results indicated that the lifeboat test configuration presented considerable challenges to usability/functionality as well as habitability. These findings suggest that further research should be conducted to evaluate the safety of all existing lifeboat designs. Finally, it is recommended that the international maritime organization (IMO) and safety of life at sea (SOLAS) Convention should mandate user-centered design evaluations for future lifeboat manufacturing.     

Mobility of acid-treated carbon nanotubes in water-saturated porous media

The production, use, and disposal of nanomaterials may inevitably lead to their appearance in water. With the development of new industries around nanomaterials, it seems necessary to be concerned about the transport of nanomaterials in the environment. In this paper, the transport of acid-treated carbon nanotubes (CNTs) in porous media was investigated. Before the mobility investigation, the stability of acid-treated CNT dispersions was studied using ultraviolet-visible spectra and it was indicated that, under the chemical conditions employed in this work, there was no apparent aggregation. The mobility investigation showed that transport of acid-treated CNTs increased with treatment time due to increase in particle zeta potential. Carbon nanotubes treated with nitric acid for 2, 6, and 12 h possessed measured zeta potentials of -30.0, -43.0, and -48.5 mV, respectively. Utilizing clean-bed filtration theory, we showed that acid-treated CNTs have the potential to migrate 3.28, 5.67, and 7.69 m in saturated glass beads, respectively. We showed that solution ionic strength and pH have important effects on the mobility of acid-treated CNTs. Increasing the pH from 6.0 to 7.9 resulted in an increase in migration potential from 2.96 to 10.86 m. Increasing the ionic strength from 0.005 to 0.020 M resulted in a decrease in CNT migration potential from 5.67 to 1.42 m.     

Environmental impacts of the shelter forests in Horqin Sandy land, northeast China

Assessing environmental effects of shelter forests is primarily necessary for realizing their greatest protective benefits. The Three-North Shelter Forest Program (TNSFP), the largest ecological afforestation program in the world, has been operated for three decades in China but so far lacks comprehensive assessment of its environmental impacts. Horqin Sandy Land (HSL) in Northeast China is one of the key areas in the TNSFP implementation. To identify the principal contributors to environmental changes in HSL, we evaluated impacts of variations in landscape features, shelter forest areas, climatic factors, and social factors on changes in sandy land areas from 1978 to 2007, by using Gray Relational Analysis. Our analysis showed that during the period 1978 to 2007, the sandy land area decreased by 3.9% in low aeolian dunes, 14.5% in low mountains and hills, and 98.9% in high elevation alluvial flats of HSL. Factors with Gray Correlation Degrees >0.9 were identified as the patch shape index (PSI) and the landscape isolation index (LII) of grasses in low aeolian dunes, PSI of grasses in mountains and hills, and area of broadleaved forests and LII of shrubs in alluvial flats. It is concluded that establishment of the shelter forests has played a significant role in controlling the expansion of sandy land in HSL. To sustain the long-term environmental benefits of the shelter forests in the remaining period for TNSFP construction, suitable tree species should be selected and planted at appropriate densities based on the local precipitation, groundwater and landform conditions, and the system stability of the total landscape.     

Controls on sediment delivery in coastal plain rivers

Rivers crossing coastal plains are often inefficient conveyors of sediment, so that changes in upstream sediment dynamics are not evident at the river mouth. Extensive accommodation space and low stream power often result in extensive alluvial storage upstream of estuaries and correspondingly low sediment loads at the river mouth. However, gaging stations with sediment records are typically well upstream of the coast, and thus tend to overestimate sediment yields by under-representing the lower coastal plain and because there is often a net loss of sediment in lower coastal plain reaches. Studies of alluvial sediment storage have generally focused on accommodation space, but, using examples from Texas, we show that low transport capacity controlled largely by slope is a crucial factor.