Sodium and chloride accumulation in leaf, woody, and root tissue of Populus after irrigation with landfill leachate

The response of Populus to irrigation sources containing elevated levels of sodium (Na(+)) and chloride (Cl(-)) is poorly understood. We irrigated eight Populus clones with fertilized well water (control) (N, P, K) or municipal solid waste landfill leachate weekly during 2005 and 2006 in Rhinelander, Wisconsin, USA (45.6 degrees N, 89.4 degrees W). During August 2006, we tested for differences in total Na(+) and Cl(-) concentration in preplanting and harvest soils, and in leaf, woody (stems+branches), and root tissue. The leachate-irrigated soils at harvest had the greatest Na(+) and Cl(-) levels. Genotypes exhibited elevated total tree Cl(-) concentration and increased biomass (clones NC14104, NM2, NM6), elevated Cl(-) and decreased biomass (NC14018, NC14106, DM115), or mid levels of Cl(-) and biomass (NC13460, DN5). Leachate tissue concentrations were 17 (Na(+)) and four (Cl(-)) times greater than water. Sodium and Cl(-) levels were greatest in roots and leaves, respectively.     

Implicating waterfronts in regional sustainability

Advocates of sustainable urban development often privilege the region as a scale for coordinated action and investment. However, discourses of sustainability institutionalised through regional planning, and conflated with notions of liveability, lend themselves to recruitment by competing, and opposing, development interests. To be regionally sustainable, an individual land development should, both on-site and through its connections to other sites, contribute to overall sustainability of the region. Using examples of industrial waterfront redevelopment in metropolitan Vancouver, we show how particular urban spaces are misrepresented as lynchpins of regional sustainability. In a plan for residential redevelopment, it is claimed that sustainable redevelopment will reunite citizens with “their waterfront”, reframed as liveable, pure, clean, ecologically vital and non-industrial. At an adjacent site, it is claimed that waterfront industrial land should be protected to combat industrial sprawl. Yet, in both cases the developers have lobbied for the expansion of road transportation making the claims of regional sustainability doubtful.     

Measurement of total site mercury emissions from a chlor-alkali plant using ultraviolet differential optical absorption spectroscopy and cell room roof-vent monitoring

This technical note describes a United States Environmental Protection Agency (U.S. EPA) measurement project to determine elemental mercury (Hg⁰) emissions from a mercury cell chlor-alkali (MCCA) facility in the southeastern U.S. during a 53-day monitoring campaign in the fall of 2006. The optical remote sensing (ORS) area source measurement method EPA OTM 10 was used to provide Hg⁰ flux data for the site. These results are reported and compared with cell room roof-vent monitoring data acquired by the facility for similar time periods. The 24-h extrapolated mercury emission rate estimates determined by the two monitoring approaches are shown to be similar with overall averages in the 400 g day^?1 range with maximum values around 1200 g day^?1. Results from the OTM 10 measurements, which include both cell room emissions and potential fugitive sources outside the cell room, are shown to be approximately 10% higher than cell room monitoring results indicating that fugitive emissions from outside the cell room produce a small but measurable effect for this site.     

南北极大气气溶胶单颗粒成分特点研究

运用定量电子探针微区分析技术(EPMA)分别测定了采自北极新奥尔松地区(78?55′N、11?56′E)和南极乔治王岛(62?13′S、58?47′W)极昼天气下PM10大气颗粒物样品.结果表明,北极和南极大气颗粒物化学成分存在很大差异,表现出各自不同的特点.北极的颗粒类型中,“反应的海盐”和“矿物尘”分别占颗粒总数的44%和27%,“新鲜海盐”所占的比例不到10%,“反应的海盐”中以含硝酸盐的颗粒为主,反映了外来物质或人为污染对该地气溶胶影响较大;南极的颗粒类型中,“新鲜海盐”占总数的74%左右,“反应的海盐”占19%,反应的海盐全部含硫酸盐、未发现含硝酸盐的颗粒,推测与海盐反应的含硫物质来源于海洋浮游生物代谢过程产生的二甲硫醚(DMS)及其降解产物,而与人为污染无关.     

Carbonate induced dissolution of uranium containing precipitates under cement leachate conditions

The effects of carbonate on uranium (VI) solubility under aerobic and cementitious conditions have been investigated. The information is of relevance to low level nuclear waste disposal. Aqueous NaOH, KOH, Ca(OH)2 and a cement leachate solution were added to uranyl nitrate solution. Afterwards, increasing amounts of ammonium carbonate were added to re-dissolve the precipitates. The precipitates were characterised by means of X-ray powder diffraction (XRPD) measurements and modelling studies. The model calculations were performed using the MINTEQA2 speciation code, with an expanded database incorporating uranium stability constants taken from the HATCHES database. The measured and predicted amounts of CO3(2-) needed to dissolve the precipitates were compared. The knowledge gained from the 'pure' systems was used to rationalise the precipitation and re-dissolution behaviour observed in the leachate system. The lack of uranium solubility at low carbonate levels brought into question literature formation constants for UO2(OH)3- and UO2(OH)4(2-). An approximate log K value of 26.8 for K2U2O7 formation was estimated from the KOH results at pH 12. Generally, uranium solubilities are expected to be insignificant at low level nuclear waste sites because anaerobic conditions should persist. However, this study has demonstrated that solubility in leachate could rise at high pH and high carbonate levels, if aerobic conditions were to develop. Soluble U(VI) species would be formed. The novel part of the study has been to reproduce the effects and to correlate enhanced solubilities with model predictions. Consequently, the study has re-emphasised the need for appropriate environmental monitoring of such sites.     

No evidence for offspring sex-ratio adjustment to social or environmental conditions in cooperatively breeding purple-crowned fairy-wrens

When fitness returns or production costs vary between male and female offspring, selection is expected to favor females that adjust offspring sex ratio accordingly. However, to what extent vertebrates can do so is the subject of ongoing debate. Here, we explore primary sex ratios in 125 broods of cooperatively breeding purple-crowned fairy-wrens Malurus coronatus. We expected that females might adjust offspring sex ratio because this passerine species experiences considerable variation in social and environmental conditions. (1) However, although helpers substantially increase parental fitness, females (particularly in pairs and small groups) did not overproduce philopatric males (helper-repayment hypothesis). (2) Sex-ratio adjustment based on competition among individuals (helper-competition hypothesis) did not conceal helper-repayment effects or drive sex allocation on its own: while high-quality territories can accommodate more birds, brood sex ratios were independent of territory quality, alone or in interaction with group size. (3) Additionally, males are larger than females and are possibly more costly to produce (costly sex hypothesis), and (4) female offspring may benefit more from long-term effects of favorable conditions early in life (Trivers–Willard hypothesis). Nonetheless, large seasonal variation in food abundance was not associated with a consistent skew in primary sex ratios. Thus, overall, our results did not support the main hypotheses of adaptive sex-ratio adjustment in M. coronatus. We discuss that long-term differential costs and benefits may be insufficient to drive evolution of primary sex-ratio manipulation by M. coronatus females. More investigation is therefore needed to determine the general required sex differences in long-term fitness returns for mechanisms of primary sex-ratio manipulation to evolve.     

Patterns of egg yolk antioxidant co-variation in an avian brood parasite–host system

Despite their importance to offspring fitness outcomes, there has been little previous work on egg-mediated maternal effects in avian brood parasites which lay their eggs in the nests of other species. Here, we examine patterns of egg yolk antioxidant deposition in an avian host (red-winged blackbird, Agelaius phoeniceus) and their brood parasite (brown-headed cowbird, Molothrus ater). Cowbird nestlings compete directly for food with host blackbird chicks and succeed, despite hatching from a smaller egg, by begging more intensely and growing as or more rapidly than their hosts. Dietary-derived antioxidants, such as carotenoids and vitamins E and A, deposited in egg yolk, may enhance growth rate and reduce oxidative stress, and therefore provide a potential mechanism by which female cowbirds could enhance the competitiveness of their young in host nests. However, provision of antioxidants to eggs is costly so we predicted that female cowbirds should adjust the amount of antioxidants in response to variation in host quality. We found that whilst red-winged blackbird clutches parasitised by cowbirds did not differ in the pattern of antioxidant deposition compared to non-parasitised clutches, levels of vitamin E deposited in cowbird eggs were closely matched to that of the individual host clutch in which cowbirds laid their egg. This supports the prediction that female cowbirds adjust the antioxidant concentration of their eggs to increase the likely competitiveness of their offspring in the host nest into which they are laid and may help explain the success of cowbirds in competing with larger host young.     

The Tyndall coastal simulator

The threat of sea-level rise and climate change means that coastal managers are being increasingly asked to make long-term assessments of potential coastal impacts and responses. In the UK, shoreline management planning (for flood and erosion hazards) and spatial planning now takes a 100 year perspective. An integrated framework across a wide range of physical and social issues is required for the assessment of coastal impacts and consequently for making sound management decisions. This paper provides an overview of the development of the ‘Tyndall Coastal Simulator’ including the underlying philosophy that is being followed. The Simulator is based on a series of linked climate models (CM) within a nested framework which recognises three spatial scales: (i) the global (GCM) scale; (ii) the regional scale and (iii) the Simulator Domain (a physiographic unit, such as a coastal sub-cell). Within the nesting, the larger scale provides the boundary conditions for the smaller scale. The models feed into each other and describe a range of relevant processes: sea level, tides, surges, waves, sediment transport and coastal morphology. Different climate scenarios, as well as the range of uncertainty, are being explored. Communication of results is a major issue and the Simulator includes a dedicated GIS-based user interface that allows a wide range of queries of model outputs. The paper demonstrates the possibility of developing an integrated framework that is multi-scale and capable of linking various models in order to simulate complex coastal processes and consequently allowing long-term assessments that are useful for setting future management plans.     

Adjusting the economy to the new energy realities of the second half of the age of oil

Our research indicates that, due to the depletion of conventional, and hence cheap, crude oil supplies (i.e. peak oil), increasing the supply of oil in the future would require exploiting lower quality resources (i.e. expensive), and thus will most likely occur only at high prices. This situation creates a system of feedbacks where economic growth, which requires more oil, would require high oil prices that will undermine that economic growth. We conclude that the economic growth of the past 40 years is unlikely to continue unless there is some remarkable change in how we manage our economy.