Streambed Sediment Geochemical Controls on In-Stream Phosphorus Concentrations during Baseflow

A spatially extensive geochemical data set of stream water and bed sediment composition across the Tamar catchment in south-west England was analysed to identify the key bed sediment properties that control the in-stream dissolved reactive phosphorus (DRP) concentrations during baseflow conditions. Linear regression analysis of the streamwater DRP concentrations and the distribution coefficient K _d for DRP revealed that the former is positively correlated with total SiO₂ and Al₂O₃, and negatively correlated with K₂O. The primary control on these major element distributions is the dominant bedrock geology. The data suggest that streamwater DRP concentrations are mainly controlled by adsorption to clay minerals. Where P concentrations in streamwater were considerably elevated by inputs from point sources, DRP concentrations are also controlled by precipitation of hydroxyapatite.     

Moorhens have an internal representation of their own eggs

How do birds recognize their own eggs? Do they have a stored template for their own egg characteristics, or do they use another mechanism? Intraspecific brood parasitism is considered to be an additional reproductive tactic where females can increase their own reproductive success. Because of the costs involved in rearing young that are not their own, it will pay females to detect and reject the eggs of a parasite, although it is not known how they do this. Here, we show experimentally that moorhens will cease laying in a nest when their first egg is replaced with another hen’s egg but not when it is replaced with their own egg taken from an earlier clutch. This provides good evidence that birds have an internal representation of their own eggs and use this in decisions about whether to reject foreign eggs.     

Approach and application of life cycle screening in early phases of process design: case study of supercritical water gasification

Process design can be influenced most in the early phases. Here, screening methods play a major role, as they reduce the complexity of a system studied by making a pre-selection from a set of alternatives available. The remaining alternatives can be analyzed in more detail in the subsequent design process, which increases design efficiency. The present paper focuses on a multi-stage screening approach for use in the early process development phase in particular. This approach is based on the use of non-compensatory decision support methods that are transferred to life cycle assessment. It may be divided into a first stage, in which the decision matrix used is developed on the basis of decision analysis principles, and a second stage, in which the decision matrix developed is further processed using non-compensatory decision support methods. An example of such a method is the pareto-dominance analysis applied here. The approach proposed is validated by application to the process of biomass gasification in supercritical water, which is being developed at the moment. Here, screening is performed to identify those life cycles, the potential environmental impacts of which contribute most to the total impacts. Attributes are selected in line with the requirement of a simple, but still sufficient modeling of these environmental impacts. By pareto-dominance analysis, emissions from the gasification of sewage sludge, the pre-chain of natural gas production, and from the construction of the supercritical gasification plant are identified to dominate over the remaining life cycles studied. Apart from the predominating alternatives, it is of particular importance to know the dominated alternatives. Due to their small shares in the result, no or only a small expenditure is needed to identify improvement potentials of these alternatives.     

PFOS levels in the blood and liver of a small insectivorous songbird near a fluorochemical plant

Perfluorooctane sulfonate (PFOS) is the stable end product of the degradation of various perfluorinated compounds and is the predominant compound found in the environment and biota. PFOS is a widespread environmental contaminant that is found in a great diversity of wildlife species with more elevated tissue concentrations in animals from populated and industrialized areas. In this study we determined the PFOS accumulation in blood and livers of a small songbird, the great tit (Parus major), in the vicinity of a large fluorochemical plant in Antwerp, Belgium. PFOS concentrations ranged from 553 ng/g to 11359 ng/g in liver and ranged from 24 to 1625 ng/ml in blood, which are among the highest ever reported in free-living animals, and exceeded in almost all birds the hepatic benchmark concentrations for the protection of avian species [Beach SA, Newsted JL, Coady K, Giesy JP. Ecotoxicological evaluation of perfluorooctanesulfonate (PFOS). Rev Environ Contam Toxicol 2006;186:133-174]. Although PFOS concentrations in liver and blood decreased significantly within approximately 5.5 km of the plant, differences were smaller than previously described for wood mice (Apodemus sylvaticus) and nestling great tits. PFOS concentrations in liver and blood were higher in young birds (one-year old). No significant sex differences were found. A highly significant correlation between liver and blood concentrations indicates the usefulness of blood as a non-destructive matrix for biomonitoring purposes.     

Eggshell strength of an obligate brood parasite: a test of the puncture resistance hypothesis

Eggs of several brood parasites have thicker and stronger shells than expected for their size. The present study evaluated the puncture resistance hypothesis for the occurrence of thick-shelled eggs in common cuckoos Cuculus canorus by investigating costs of cuckoo egg ejection in four Acrocephalus warblers—the great reed warbler A. arundinaceus, reed warbler A. scirpaceus, marsh warbler A. palustris and sedge warbler A. schoenobaenus. The three latter species all suffered ejection costs, while ejection was not costly in the larger great reed warbler. The occurrence of ejection costs was negatively related to host bill size. In the marsh warbler, we compared ejection costs in naturally parasitized nests and two experimental treatments, in which broods were parasitized artificially with great reed warbler and conspecific eggs. Hosts damaged their own eggs significantly more often when ejecting the thick-shelled cuckoo eggs than when ejecting the similarly sized but thinner-shelled great reed warbler eggs, providing some support for the puncture resistance hypothesis. Ejection of conspecific eggs did not involve any costs. Furthermore, contrary to predictions derived from the laying damage hypothesis, there was no evidence that egg damage was associated with cuckoo egg laying. Hosts damaging their own eggs during ejection were more likely to subsequently desert their clutches than those that did not. The frequency of clutches smeared with the contents of the ejected egg were positively related to the hypothesized difficulty of foreign egg puncturing. Potential advantages of thicker shells in common cuckoo eggs are discussed.     

新型多级冲击采样器切割粒径的标准粒子实验分析

大气溶胶对环境污染、气候变化以及人体健康有着重要的影响,大气溶胶的采集和分析已成为当前大气环境研究领域中的一个重要课题.论述的新型多级冲击采样器能够实现大气溶胶颗粒物按空气动力学粒径的大小7级分离采集,提供大致均匀的平面样品以进行后续的物理、化学分析,同时保证各分级切割粒径的稳定性.利用振动孔溶胶发生器产生均匀、粒径大致相同、单分散相的1.5～17μm空气动力学粒径标准粒子,对新型多级冲击采样器前三级的切割粒径和收集效率进行鉴定性分析实验,结果表明,能够满足对大气溶胶颗粒物分级采集的要求.     

Individual preparedness and mitigation actions for a predicted earthquake in Istanbul

This study investigated the process of taking action to mitigate damage and prepare for an earthquake at the individual level. Its specific aim was to identify the factors that promote or inhibit individuals in this process. The study was conducted in Istanbul, Turkey—where an earthquake is expected soon—in May and June 2006 using qualitative methods. Within our conceptual framework, three different patterns emerged among the study subjects. Outcome expectancy, helplessness, a low socioeconomic level, a culture of negligence, a lack of trust, onset time/poor predictability, and normalisation bias inhibit individuals in this process, while location, direct personal experience, a higher education level, and social interaction promote them. Drawing on these findings, the paper details key points for better disaster communication, including whom to mobilise to reach target populations, such as individuals with direct earthquake experience and women.     

Controls on catchment-scale patterns of phosphorus in soil, streambed sediment, and stream water

Many models of phosphorus (P) transfer at the catchment scale rely on input from generic databases including, amongst others, soil and land use maps. Spatially detailed geochemical data sets have the potential to improve the accuracy of the input parameters of catchment-scale nutrient transfer models. Furthermore, they enable the assessment of the utility of available, generic spatial data sets for the modeling and prediction of soil nutrient status and nutrient transfer at the catchment scale. This study aims to quantify the unique and joint contribution of soil and sediment properties, land cover, and point-source emissions to the spatial variation of P concentrations in soil, streambed sediments, and stream water at the scale of a medium-sized catchment. Soil parent material and soil chemical properties were identified as major factors controlling the catchment-scale spatial variation in soil total P and Olsen P concentrations. Soil type and land cover as derived from the generic spatial database explain 33.7% of the variation in soil total P concentrations and 17.4% of the variation in Olsen P concentrations. Streambed P concentrations are principally related to the major element concentrations in streambed sediment and P delivery from the hillslopes due to sediment erosion. During base flow conditions, the total phosphorus (<0.45 microm) concentrations in stream water are mainly controlled by the concentrations of P and the major elements in the streambed sediment.     

Reconciling empirical ecology with neutral community models

Neutral community models embody the idea that individuals are ecologically equivalent, having equal fitness over all environmental conditions, and describe how the spatial dynamics and speciation of such individuals can produce a wide range of patterns of distribution, diversity, and abundance. Neutral models have been controversial, provoking a rush of tests and comments. The debate has been spurred by the suggestion that we should test mechanisms. However, the mechanisms and the spatial scales of interest have never clearly been described, and consequently, the tests have often been only peripherally relevant. At least two mechanisms are present in spatially structured neutral models. Dispersal limitation causes clumping of a species, which increases the strength of intraspecific competition and reduces the strength of interspecific competition. This may prolong coexistence and enhance local and regional diversity. Speciation is present in some neutral models and gives a donor-controlled input of new species, many of which remain rare or are short lived, but which directly add to species diversity. Spatial scale is an important consideration in neutral models. Ecological equivalence and equal fitness have implicit spatial scales because dispersal limitation and its emergent effects operate at population levels, and populations and communities are defined at a chosen spatial scale in recent neutral models; equality is measured relative to a metacommunity, and this necessitates defining the spatial scale of that metacommunity. Furthermore, dispersal has its own scales. Thorough empirical tests of neutral models will require both tests of mechanisms and pattern-producing ability, and will involve coupling theoretical models and experiments.     

Interactive effects of disturbance and dispersal directionality on species richness and composition in metacommunities

Dispersal among ecological communities is usually assumed to be random in direction, or to vary in distance or frequency among species. However, a variety of natural systems and types of organisms may experience dispersal that is biased by directional currents or by gravity on hillslopes. We developed a general model for competing species in metacommunities to evaluate the role of directionally biased dispersal on species diversity, abundance, and traits. In parallel, we tested the role of directionally biased dispersal on communities in a microcosm experiment with protists and rotifers. Both the model and experiment independently demonstrated that diversity in local communities was reduced by directionally biased dispersal, especially dispersal that was biased away from disturbed patches. Abundance of species (and composition) in local communities was a product of disturbance intensity but not dispersal directionality. High disturbance selected for species with high intrinsic growth rates and low competitive abilities. Overall, our conclusions about the key role of dispersal directionality in (meta)communities seem robust and general, since they were supported both by the model, which was set in a general framework and not parameterized to fit to a specific system, and by a specific experimental test with microcosms.