Mineralogical composition and pore fluid pressure are the crucial controls for mechanical stability of water-saturated sediments. Their in situ measurements were undertaken in earthquake-triggered slope deposits in Lake Lucerne (Switzerland) in addition to geophysical characterization and laboratory index properties, shear and consolidation experiments on core. Two lithological units were identified: A weak, lightly underconsolidated section of postglacial silty clays overlies overconsolidated fine-grained glacial deposits with coarser components and excess fluid pressure (ca. 2.5 × higher than in the hanging wall clay). In the event of an earthquake, hydrofracturing in the overconsolidated section facilitates an upward pore pressure pulse to the base of the softer, less stable unit. Here, excess pore pressure initiates sliding along a failure plane at the lithological boundary, causing the entire postglacial sedimentary section to slip downslope. We propose that many submarine landslides at active and passive continental margins may follow this mechanism of pore pressure-induced failure.

The Minqin Basin is a type area for examining stress on groundwater resources in the Gobi Desert, and has been investigated here using a combination of isotopic, noble gas and chemical indicators. The basin is composed of clastic sediments of widely differing grain size and during the past half century over 10 000 boreholes have been drilled with a groundwater decline of around 1 m a<SUP>-1</SUP>. Modern diffuse recharge is unlikely to exceed 3 mm a<SUP>-1</SUP>, as determined using unsaturated zone profiles and Cl<SUP>-</SUP> mass balance. A small component of modern (<50 a) groundwater is identified in parts of the basin from <SUP>3</SUP>H-<SUP>3</SUP>He data, probably from irrigation returns. A clear distinction is found between modern waters with median δ<SUP>18</SUP>O values of 6.5 ± 0.5‰ and most groundwaters in the basin with more depleted isotopic signatures. Radiocarbon values as pmc range from 0.6% to 85% modern, but it is difficult to assign absolute ages to these, although a value of 20% modern C probably represents the late Pleistocene to Holocene transition. The δ<SUP>13</SUP>C compositions remain near-constant throughout the basin (median value of -8.1‰ δ<SUP>13</SUP>C) and indicate that carbonate reactions are unimportant and also that little reaction takes place. There is a smooth decrease in <SUP>14</SUP>C activity accompanied by a parallel increase in <SUP>4</SUP>He accumulations from S-N across the basin, which define the occurrence of a regional flow system. Noble gas temperatures indicate recharge temperatures of about 5.6 °C for late Pleistocene samples, which is some 2-3 °C cooler than the modern mean annual air temperature and the recharge temperature obtained from several Holocene samples. Groundwaters in the Minqin Basin have salinities generally below 1 g/L and are aerobic, containing low Fe but elevated concentrations of U, Cr and Se (mean values of 27.5, 5.8 and 5.3 μg L<SUP>-1</SUP>, respectively). Nitrate is present at baseline concentrations of around 2 mg L<SUP>-1</SUP> but there is little evidence of impact of high NO<SUB>3</SUB> from irrigation returns. Strontium isotope and major ion ratios suggest that silicate reactions predominate in the aquifer. The results have important implications for groundwater management in the Minqin and other water-stressed basins in NW China - a region so far destined for rapid development. The large proportion of the water being used at present is in effect being mined and significant changes are urgently needed in water use strategy.

An increasing number of studies have documented phenotypic selection on life-history traits in human populations, but less is known of the heritability and genetic constraints that mediate the response to selection on life-history traits in humans. We collected pedigree data for four generations of preindustrial (1745-1900) Finns who lived in premodern fertility and mortality conditions, and by using a restricted maximum-likelihood animal-model framework, we estimated the heritability of and genetic correlations between a suite of life-history traits and two alternative measures of fitness. First, we demonstrate high heritability of key life-history traits (fecundity, interbirth interval, age at last reproduction, and adult longevity) and measures of fitness (individual lambda and lifetime reproductive success) for females but not for males. This sex difference may have arisen because most of the measured traits are under physiological control of the female, such that a male's fitness in monogamous societies may depend mainly on the reproductive quality of his spouse. We found strong positive genetic correlations between female age at first reproduction and longevity, and between interbirth intervals and longevity, suggesting reduced life spans in females who either started to breed relatively early or who then bred frequently. Our results suggest that key female life-history traits in this premodern human population had high heritability and may have responded to natural selection. However genetic constraints between longevity and reproductive life-history traits may have constrained the evolution of life history and facilitated the maintenance of additive genetic variance in key life-history traits.

Adaptive radiations are an important source of biodiversity, but resolving which ecological pressures seed these processes in natural systems remains difficult. Here the adaptive radiation among <I>Telmatherina</I>, a genus of freshwater fish endemic to an ancient lake in central Sulawesi, Indonesia, was examined to determine its causal root. We demonstrate that all <I>Telmatherina</I> in this lake can be categorized into three lineages each possessing specialized skull shapes and pharyngeal jaw bones allowing them to exploit different resources. These data demonstrate a natural example of how resource partitioning has likely initiated adaptive radiation in a resource limited environment.

Expression profiling of exposed cells or organisms can reveal genes sensitive to environmental contaminants or toxic compounds. However, the mechanistic relevance of altered gene expression often remains to be elucidated. Toxicant-dependent differential gene expression may indicate protection to or mediation of toxicity. Previous studies revealed a number of differentially transcribed genes in zebrafish embryos exposed to the model compound 3,4-dichloroaniline (3,4-DCA). To evaluate the significance of two of the most sensitive genes, cytochrome P 450 1a (<I>cyp1α</I>) and heme oxygenase 1 (<I>hmox1</I>), for 3,4-DCA toxicity, RNA interference-mediated knockdown and overexpression studies have been conducted. Knockdown of gene transcription by siRNA for <I>cyp1α</I> and <I>hmox1</I> enhanced the frequency of developmental disorders in embryos exposed to 3,4-DCA. Vice versa, injection of <I>cyp1α</I> and <I>hmox1</I> mRNA reduced the number of disorders. The opposite effects of siRNA and mRNA injection clearly indicate a protective role of the corresponding proteins. Functional studies such as the one presented could be applied to a wide variety of genes. They would be ideally suited to study the role of genes identified from toxicogenomic studies in the zebrafish embryo model.

High-iron sediments in North Haiwee Reservoir (Olancha, CA), resulting from water treatment for removal of elevated dissolved arsenic in the Los Angeles Aqueduct system, were studied to examine arsenic partitioning between solid phases and porewaters undergoing shallow burial. To reduce arsenic in drinking water supplies, ferric chloride and a cationic polymer coagulant are added to the aqueduct upstream of Haiwee Reservoir, forming an iron-rich floc that scavenges arsenic from the water. Analysis by synchrotron X-ray absorption spectroscopy (XAS) showed that the aqueduct precipitate is an amorphous hydrous ferric oxide (HFO) similar to ferrihydrite, and that arsenic is associated with the floc as adsorbed and/or coprecipitated As(V). Arsenic-rich floc and sediments are deposited along the inlet channel as aqueduct waters enter the reservoir. Sediment core samples were collected in two consecutive years from the edge of the reservoir along the inlet channel using 30- or 90-cm push cores. Cores were analyzed for total and extractable arsenic and iron concentrations. Arsenic and iron speciation and mineralogy in sediments were examined at selected depths by synchrotron XAS and X-ray diffraction (XRD).Sediment–porewater measurements were made adjacent to the core sample sites using polyacrylamide gel probe samplers. Results showed that sediment As(V) is reduced to As(III) in all cores at or near the sediment–water interface (0–4 cm), and only As(III) was observed in deeper sediments. Analyses of EXAFS spectra indicated that arsenic is present in the sediments mostly as a bidentate–binuclear, inner-sphere sorption complex with local atomic geometries similar to those found in laboratory studies. Below about 10 cm depth, XAS indicated that the HFO floc had been reduced to a mixed Fe(II, III) solid with a local structure similar to that of synthetic green rust (GR) but with a slightly contracted average interatomic Fe–Fe distance in the hydroxide layer. There was no evidence from XRD for the formation of a crystalline GR phase. The release of dissolved iron (presumably Fe<SUP>2+</SUP>) and arsenic to solution, as monitored by <I>in situ</I> gel probes, was variable but, in general, occurred at greater depths than arsenic reduction in the sediments by spectroscopic observations and appears to be near or below the depth at which sediment GR was identified. These data point to reductive dissolution of the sorbent iron phase as the primary mechanism of release of sorbed arsenic to solution.

Located at 54º S in the heart of the Island of Tierra del Fuego, Lago Fagnano occupies the deepest of a chain of <I>en-echelon</I> tectonic depressions along the Magallanes-Fagnano Transform system (MFT). A recent geophysical campaign combining 3.5 kHz (pinger) single-channel with 1 in3 airgun multi-channel systems surveyed more than 100 m of glacio-lacustrine sediments filling two main sub-basins. These data provide a unique opportunity to visualize the most recent lacustrine sequence with high-resolution while simultaneously imaging the oldest infill. A preliminary seismic stratigraphic analysis of the high-resolution 3.5 kHz pinger data allowed the identification of three major seismostratigraphic units (A, the oldest and C, the youngest). While unit A is interpreted as glacially derived sediments, the overlying unit B is interpreted as fining upward sequences of proglacial turbidites reflecting sediment pulses released by the retreating Fagnano glacier during the last deglaciation. A major environmental change occurred during deposition of unit C when pelagic style of sedimentation is intercalated by sequences of downslope mass flow events probably triggered by relatively strong tectonic pulses along the MFT system. Gravity cores show a regular alternation of light and dark laminae occasionally interrupted by homogenous sedimentary units interpreted as turbidites. Ultra-high resolution X-ray fluorescence micro-profiles show fluctuations in major trace elements at mm scale that may indicate seasonal variations in the sedimentary influx. These core data provide a unique record of decadal changes in regional climate that can be compared with other marine and continental archives to improve our understanding of the forcing mechanisms behind climate change.

Background: Orthologous genes are frequently presumed to perform similar functions. However, outside of model organisms, this is rarely tested. One means of inferring changes in function is if there are changes in the level of gene conservation and selective constraint. Here we compare levels of gene conservation across three bacterial groups to test for changes in gene functionality.<br /> Findings: The level of gene conservation for different orthologous genes is highly correlated across clades, even for highly divergent groups of bacteria. These correlations do not arise from broad differences in gene functionality (e.g. informational genes vs. metabolic genes), but instead seem to result from very specific differences in gene function. Furthermore, these functional differences appear to be maintained over very long periods of time.<br /> Conclusion: These results suggest that even over broad time scales, most bacterial genes are under a nearly constant level of purifying selection, and that bacterial evolution is thus dominated by selective and functional stasis.

In this study the effects of 3,4-dichloroaniline (3,4-DCA), a decomposition product of the herbicides propanil and diuron (and other pesticides), and diazinon, a neurotoxic insecticide, on early life stages of zebrafish <I>Danio rerio</I> were assessed. The toxicity of these substances with different modes of action (acetylcholine esterase inhibitor vs. polar narcosis) was tested for single substances as well as in binary mixtures. To study effects on different biological organisation levels (from the molecular up to the whole organism level) the molecular stress response regarding Hsp70, the embryonic and larval development and the locomotor activity were investigated as integrative biomarkers. In single substance tests 3,4-dichloroaniline elicited deformations at ≥0.25 mg/l during the 11 days subchronic test, whereas locomotor activity and mortality were impaired at ≥0.5 mg/l. Diazinon effects on those parameters were obvious at ≥2 mg/l, except for the deformation rate (11 days:1 mg/l). In equitoxic mixtures of both substances concentration additivity was observed for deformation rate and mortality (11 days). An increase in the Hsp70 content occurred in zebrafish exposed to 0.25 mg 3,4-DCA/l as well as to 0.05 mg diazinon/l; in mixtures concentration additivity could be shown. The investigated endpoints varied in respect to their sensitivity, with deformations and Hsp70 levels as most sensitive parameters concerning 3,4-DCA and Hsp70 as most sensitive parameter concerning diazinon. Accordingly, for an integrated understanding of the effects of chemicals and their mixtures on fish, a battery of different test methods should be applied.

In order to assess the combined toxicity of environmental chemicals with different modes of action in acute (2 h) and subchronic (11 d) exposures, embryos and larvae of <I>Danio rerio</I> were exposed to a heavy metal salt, nickel chloride (NiCl<SUB>2</SUB>), the insecticide chlorpyrifos (CHP) and their binary mixtures. Chlorpyrifos is an acetylcholine esterase inhibitor, which is likely to affect behaviour of the organism. NiCl<SUB>2</SUB> targets the active sites of enzymes and is regarded as an unspecific toxicant for aquatic organisms. Several endpoints, such as locomotor activity, morphological abnormalities, and mortality of <I>D. rerio</I> embryos and larvae were studied. During acute exposures to ⩾0.25 mg/L of chlorpyrifos, locomotor activity tended to increase. However, this activity decreased significantly at ⩾7.5 mg Ni/L. Subchronic exposures to CHP resulted in behavioural changes at much lower concentrations (⩾0.01 mg/L) and considerably earlier than the observed increase in morphological abnormalities and mortality (LC<SUB>50</SUB> (10 d): 0.43 mg/L). Combined CHP and NiCl<SUB>2</SUB> mixtures led to an antagonistic deviation from the concept of independent action, in the case of locomotor activity. Compared to developmental or survival parameters, behaviour was the most sensitive endpoint for CHP exposure in this study; therefore we recommend this parameter to complement already established endpoints.

As mathematical modeling of wastewater treatment plants has become more common in research and consultancy, a mismatch between education and requirements for model-related jobs has developed. There seems to be a shortage of skilled people, both in terms of quantity and in quality. In order to address this problem, this paper provides a framework to outline different types of model-related jobs, assess the required skills for these jobs and characterize different types of education that modelers obtain “in school” as well as “on the job”. It is important to consider that education of modelers does not mainly happen in university courses and that the variety of model related jobs goes far beyond use for process design by consulting companies. To resolve the mismatch, the current connection between requirements for different jobs and the various types of education has to be assessed for different geographical regions and professional environments. This allows the evaluation and improvement of important educational paths, considering quality assurance and future developments. Moreover, conclusions from a workshop involving practitioners and academics from North America and Europe are presented. The participants stressed the importance of non-technical skills and recommended strengthening the role of realistic modeling experience in university training. However, this paper suggests that all providers of modeling education and support, not only universities, but also software suppliers, professional associations and companies performing modeling tasks are called to assess and strengthen their role in training and support of professional modelers.

The quantification of biofilm structure based on image analysis requires a statistical measure like representative elemental areas (REA) to determine the necessary size of biofilm area to be imaged. In this study, REAs for biofilm structure were calculated for the descriptors <I>Gray level</I> and <I>Correlation</I> (<I>COR</I>) derived from a spatial gray level dependence matrix analysis (SGLDM). An important difference between these two descriptors is their response to structural features at different spatial scales. <I>Gray level</I> is a scale-independent descriptor, whereas <I>COR</I> is scale-dependent. For scale-independent descriptors, the size of the individual images is not relevant when determining REAs. This is in contrast to scale-dependent descriptors for which REAs can only be determined when the area of each image covers the range of structural variability of the biofilm. We used <I>COR</I> to analyze scale dependence of structural heterogeneity at different length scales. A characteristic length of 400 µm in biofilm images provides structural information relevant for mass transport phenomena in biofilms. Overall REAs for <I>gray level</I> and <I>COR</I> were on average 3.4 mm<SUP>2</SUP>. The scale-dependent descriptor <I>COR</I> could not in all cases accurately be determined from combining individual image analysis results - even when the combined area resulted in the REA. Microscope and camera specifications define the upper and lower limit of detectable characteristic length that can be extracted from images and should therefore be considered in the experimental design when choosing an imaging technique.

The macrostructure development of biofilms grown in a lab-scale rotating biological contactor was monitored by analyzing the average opacity and the texture of gray-level images of the discs. The reactor was fed with municipal or synthetic wastewater. Experiments lasted on average 4-14 weeks. The images were obtained with a flat-bed scanner. The opacity and its standard deviation are directly extracted from the annular zone where the biofilm develops. This zone is defined by the outer edge of the disc and the waterline. The spatial gray-level dependence matrix (SGLDM) approach was used for the texture assessment. As this method requires rectangular images, a geometrical transformation had to be developed to transform the ring into a workable area. This transformation now allows quantitative image analysis on circular biofilms. As a last step, Principal Components Analysis was applied to the set of textural descriptors to reduce the number of textural parameters. Opacity and textural information allowed the non-intrusive monitoring of the growth/regrowth of the biofilms as well as biofilm loss, due to detachment, auto-digestion, or protozoan grazing. Textural description was very valuable by helping to discriminate biofilms of similar opacity characteristics but presenting different macrostructures.