Badges of status and the cost of aggression

Summary The badges of status hypothesis suggests that frequency-dependent selection can maintain honest signalling of aggressiveness. Analysis of a simple ESS model reveals that this is only possible if aggressive individuals incur a cost independent of any particular fights they become involved in. Without such a cost, an honest population is vulnerable to invasion by a modest mutant bearing a dishonestly small badge. Analysis of a second model reveals that where individuals differ in their ability to bear the contest-independent cost of aggressiveness, badge size should reflect this ability. Under such circumstances, plumage badges which serve as honest status signals may have functional consequences beyond their role in settling contests. Thus females, when choosing a mate, could make good use of the information that plumage badges provide. Analysis of a third model shows that the existence of contest-independent benefits to badge size, such as increased mating success, is compatible with the maintenance of honest status signalling.Correspondence to: R.A. Johnstone     

运行方式对人工快渗系统水质净化效果的影响

以天然砂作为主要渗滤介质,建立污水处理人工快速渗滤系统(CRI).分别以洗浴污水、生活污水和受污染河水作为研究对象,在相同的水力负荷条件下,用两种不同的运行方式(定期投配一定量的污水、淹水和落干交替运行)对不同水质的污染物去除效果进行了对比研究.结果表明,通过缩短淹水周期,加大系统淹水和落干的频率,可以明显改善CRI系统的污染物去除效果.     

Bench-scale testing of a novel soil PFAS treatment train for informed remedial planning and decision-making

Bench-scale batch tests were conducted to assess the potential applicability of a combined separation/concentration/destruction treatment train to address soils and sediments impacted by per- and polyfluoroalkyl substances (PFAS) contamination at Schriever Space Force Base with historic aqueous film-forming foam (AFFF). Specifically, a novel treatment train coupling soil washing (for treatment of impacted soil/sediment) with foam fractionation (for treatment of the wash water [WW] generated during soil washing) and electrochemical oxidation (ECO, for treatment of the foam fractionate generated during foam fractionation) was evaluated at the bench scale using site-specific materials. Results presented herein show that the AFFF-impacted sandy soils with low organic content were amenable to treatment via soil washing. However, the removal of hydrophobic PFAS, such as perfluorooctanesulfonic acid (PFOS), from the organic-rich sediments was challenging. Results from batch desorption experiments were within a factor of 2 of those generated by soil washing bench studies, suggesting that simple batch tests can potentially be used to reasonably predict the treatment efficacy of soil washing. Long-chained perfluoroalkyl acids (PFAAs) within the WW were removed more effectively in the foam fractionation studies as compared to short-chain PFAAs. Addition of a surfactant, such as cetrimonium bromide (CTAB), enhanced foaming but only marginally improved the treatment of short-chained PFAAs and in some cases inhibited PFOS removal. ECO reduced PFAS concentrations in the foam fractionate generated during foam fractionation by several orders of magnitude. However, generation of unwanted byproducts may warrant further treatment and/or disposal. Overall, results from this study provide a novel data set highlighting the site-dependent nature of these PFAS remedial technologies and how simple, low-cost bench tests can be reliably leveraged for informed decision-making during PFAS remedial planning.     

The release of lindane from contaminated building materials

The release of the organochlorine pesticide lindane (γ-hexachlorocyclohexane) from several types of contaminated building materials was studied to assess inhalation hazard and decontamination requirements in response to accidental and/or intentional spills. The materials included glass, polypropylene carpet, latex-painted drywall, ceramic tiles, vinyl floor tiles, and gypsum ceiling tiles. For each surface concentration, an equilibrium concentration was determined in the vapour phase of the surrounding air. Vapor concentrations depended upon initial surface concentration, temperature, and type of building material. A time-weighted average (TWA) concentration in the air was used to quantify the health risk associated with the inhalation of lindane vapors. Transformation products of lindane, namely α-hexachlorocyclohexane and pentachlorocyclohexene, were detected in the vapour phase at both temperatures and for all of the test materials. Their formation was greater on glass and ceramic tiles, compared to other building materials. An empiric Sips isotherm model was employed to approximate experimental results and to estimate the release of lindane and its transformation products. This helped determine the extent of decontamination required to reduce the surface concentrations of lindane to the levels corresponding to vapor concentrations below TWA.     

Assessment of decadal changes in sediment contamination in a large connecting channel (Detroit River,North America)

Concentrations of selected heavy metals (Cd, Cu, Hg, Pb, Zn) and organic contaminants (PCBs, PAHs) were investigated in samples from the Detroit River (Great Lakes, North America) in 1999 and 2008/09 collected using a stratified random sampling design. Getis–Ord geospatial analysis was used to further establish locations of areas demonstrating significantly high and low contaminant concentrations in the river. Based on the stratified random sampling design, a majority of the examined metals and organic contaminants demonstrated little or no trends with respect to regional sediment concentrations and river-wide mass balances over the investigated time interval. The Getis–Ord analysis revealed local scales of contaminated and clean areas which did not conform to the original strata used in the geostatistical sampling design. It is suggested that geospatial analyses such as Getis–Ord be used in the design of future sediment quality surveys to refine locations of strata that can simultaneously address sediment recovery over system-wide, regional and local spatial scales.     

Trends of PCDD/F and PCB concentrations and depositions in ambient air in Northwestern Germany

Time series of polychlorinated dioxins and furans (PCDD/F) and polychlorinated biphenyls (PCB) in ambient air of a large conurbation in North-Western Germany are presented and analyzed. The trend of PCDD/F concentrations, starting from as early as 1988, shows a pronounced decrease by at least one order of magnitude, demonstrating that the emission reductions were effective. The PCDD/F depositions also have decreased by a factor of 5 since 1992. However, both trends have leveled out since 2005. Time series of PCB concentrations and depositions starting in 1994 show only slight decreases for the concentrations and almost no decrease for the depositions. From the decay rates following first order kinetics, half-lives in the order of 5-15 years for the PCDD/F and 15-31 years for the sum of the six indicator PCB could be calculated, which are much longer than the half-lives estimated from their reactivity towards the OH radical. Apparently, small fresh emissions (PCDD/F), considerable secondary emissions and evaporation from contaminated soils slow down their decay in the atmosphere of big conurbations. Analyzing the decay rates of individual PCB congeners shows that the lower chlorinated and more volatile ones are removed faster than the higher chlorinated congeners, probably via gas phase reactions with the OH radical. It can be concluded from the present study that the input of PCDD/F and PCB into the food chain via the air path will continue for another one or two decades in big conurbations.     

Assessment of groundwater vulnerability in the Yinchuan Plain,Northwest China using OREADIC

Groundwater vulnerability assessments provide a measure of the sensitivity of groundwater quality to an imposed contaminant load and are globally recognized as an essential element of all aquifer management and protection plans. In this paper, the vulnerability of groundwaters underlying the Yinchuan Plain of Northwest China is determined using OREADIC, a GIS-based assessment tool that incorporates the key characteristics of the universally popular DRASTIC approach to vulnerability assessment but has been modified to consider important additional hydrogeological factors that are specific to the region. The results show that areas of high vulnerability are distributed mainly around Qingtongxia City, Wuzhong City, Lingwu City, and Yongning County and are associated with high rates of aquifer recharge, shallow depths to the water table, and highly permeable aquifer materials. The presence of elevated NO₃⁻ in the high vulnerability areas endorses the OREADIC approach. The vulnerability maps developed in this study have become valuable tools for environmental planning in the region and will be used for predictive management of the groundwater resource.     

Anthropogenic pollution and variability of manganese in alluvial sediments of the Yellow River,Ningxia, northwest China

Heavy metal pollution of sediments is a global concern and can be a serious problem in heavily industrialized parts of the world. Pollution by manganese is particularly common due to its ubiquitous natural occurrence, ease of mobilization, and extensive association with industry. In Ningxia, China, manganese pollution of Yellow River alluvial sediments was assessed by comparing manganese concentrations in 35 sediment samples with background values derived from similar sediments obtained at sites considered remote from potential sources of contamination. Natural background values of manganese were found to range from 192 to 323 mg/kg for surface sediments, and from 220 to 325 and 283 to 394 mg/kg for subsurface sediments at depths of 45–50 and 95–100 cm, respectively. In the study area, manganese content ranged from 565 to 1,363 mg/kg, indicating anthropogenic pollution extending to a depth of at least 1 m in the study area. All 35 samples were found to exceed the threshold effect concentration (TEC) of 460 mg/kg, below which adverse effects on sediment-dwelling organisms are not expected to occur, and one sample (T12) was found to exceed the probable effect concentration (PEC) of 1,100 mg/kg. PEC defines the threshold above which adverse effects are likely to be observed. Variogram analysis of the surface sediment manganese data revealed adherence to a Gaussian model, and ordinary kriging was used to generate a manganese distribution map. Analysis of the high nugget effect ratio indicates high, small-scale variations that are consistent with potential emissions from an adjacent electrolytic manganese plant.     

Continuous and filter-based measurements of PM2.5 nitrate and sulfate at the Fresno Supersite

PM(2.5) nitrate [Formula: see text] and sulfate ([Formula: see text]) were measured continuously with R&P8400N and R&P8400S instruments, respectively, and compared with filter-based measurements at the Fresno Supersite from October, 2000 through December, 2005. [Formula: see text] concentrations were higher in winter than summer with a long-term decreasing trend. Correlations between 24-h average continuous and filter-based [Formula: see text] were greater than 0.96 in 4 out of 5 years. Continuous [Formula: see text] was generally lower than filter-based [Formula: see text] although the difference decreased over time, from -52% in 2001 to +13% in 2005. These differences were similar in winter (-23%) and summer (-19%) while the corresponding differences between ambient and instrument temperature were -12 and 0.7 degrees C, respectively. Neither seasonal nor long-term trends in [Formula: see text] can be explained by variations in ambient temperature, the difference between ambient and instrument temperature, or changes in aerosol chemical composition. There were no seasonal or long-term trends in [Formula: see text] concentrations, partially due to low concentrations observed in Fresno. Long-term variability in the performance of R&P8400 [Formula: see text] and [Formula: see text] instruments suggest that collocation with filter measurements is needed for long-term measurements.