Managing water for life

Water is essential for life. In spite of the entire engineering infrastructure devoted to the treatment, regulation and beneficial uses of water, occasionally sufficient quantities and qualities of water become scarce. When this happens, just how do we decide how much less water to allocate to all of us and the activities we engage in to sustain and enhance our quality of life? This paper addresses some of the complexities of answering such a question, especially as society increasingly recognizes the need to provide flow regimes that will maintain healthy aquatic and floodplain ecosystems that also impact the economic, physical and even the spiritual quality of our lives. For we depend on these ecosystems to sustain our wellbeing. We are indeed a part of our ecosystems. We depend upon on aquatic ecosystems to moderate river flow qualities and quantities, reduce the extremes of floods and droughts, reduce erosion, detoxify and decompose waterborne wastes, generate and preserve flood plain soils and renew their fertility, regulate disease carrying organisms, and to enhance recreational benefits of river systems. This question of deciding just how much water to allocate to each water user and for the maintenance of viable aquatic ecosystems, especially when there is not enough, is a complex, and largely political, issue. This issue is likely to become even more complex and political and contentious in the future as populations grow and as water quantities and their qualities become even more variable and uncertain.     

Influence of residency and social odors in interactions between competing native and alien rodents

Residency status of individuals in populations may be an important determinant of the outcomes of interspecific competition between native and introduced species. We examined direct behavioral interactions between two similarly sized rodents, the alien Rattus rattus and native Rattus fuscipes when they were respective residents and intruders in a small enclosure. Resident individuals were dominant in their behaviors toward intruders irrespective of the species that was resident. In contrast, interactive behaviors between conspecifics were often neutral or amicable, supporting suggestions that R. rattus and R. fuscipes are social animals. We then tested whether rodent species use heterospecific odors to avoid aggressive competitive interactions and partition space in the field. Neither R. fuscipes nor R. rattus responded to traps scented with the odors of male or female heterospecifics. If R. fuscipes does not recognize the odor of introduced R. rattus, then odors will not be cues to the presence or territorial space of competing heterospecifics. Rather, findings from both enclosure and field trials suggest that direct aggressive interactions between individual R. rattus and R. fuscipes probably facilitate segregation of space between these two species in wild populations, where resident animals may typically be the winners and exclude heterospecific intruders. These findings have implications for the invasion success of introduced rodents such as R. rattus into intact forests, where native populations may have competitive advantage because of their residency status.     

Metal fractionation of cadmium, lead and arsenic of geogenic origin in topsoils from the Marrancos gold mineralisation, northern Portugal

The Marrancos gold mineralisation has a chemical assemblage of Fe–As–Se–Bi–Au–Ag–Te–(Cu–Pb–Zn–Sn–W). The −200 mesh of 144 topsoil samples was analysed by ICP–MS to determine total contents of 53 elements that include potentially harmful elements like Cd, As and Pb. The soil geochemistry shows that some trace elements occur in considerably high concentrations. On the basis of data for total metal concentrations, 10 topsoil samples were selected to carry out a metal fractionation study using a selective extraction method. A set of four leaches of increasing strength was used sequentially in the soil samples. Across the study area, there is some evidence of past mining and exploration activity, indicating that these soils may be locally disturbed. The shallow mineralised quartz veins were exploited for gold by the Romans. Several galleries were constructed during the 2nd World War, probably for the exploration of quartz–cassiterite–wolframite veins. However, the main mineralised body in depth was never explored. The results of metal fractionation show different partitions for the three elements. Total Cd concentrations in these soils are low, with a median value of 0.1 mg/kg. In average, 12% of total Cd is adsorbed by clays and/or co-precipitated with carbonates, and 19% is bounded to Fe–Mn oxyhydroxides. However, the low concentrations indicate that the metal does not represent an immediate risk to human health. For Pb, metal fractionation shows that, on average, 22% of Pb is adsorbed by amorphous Fe and Mn oxides, but the samples from the northern part of the area have the major fractions of Pb in soluble forms. The low probability of exposure in this part of the study area decreases the risk posed by this heavy metal. Total As concentrations in the Marrancos soils are extremely high. A large area has As concentrations above 1,000 mg/kg. For As, metal fractions in the sulphide phase vary between 84 and 98% in the studied samples. But one sample has 20% of total As in easily reducible forms, corresponding to a partial concentration of 1,800 mg/kg that has a high probability of being bioavailable. The most labile As forms occur at the southern part of the area, where the probability of exposure is higher and the risk of human health increases in the same order. From the three studied potentially harmful elements, As is certainly the element of concern.     

Combining fishing and acoustic monitoring data to evaluate the distribution and movements of spotted ratfish <Emphasis Type="Italic">Hydrolagus colliei</Emphasis>

Direct and indirect methods have been used to describe patterns of movement of fishes, but few studies have compared these methods simultaneously. We used 20 years of trawl survey data and 1 year of acoustic telemetry data to evaluate the vertical and horizontal movement patterns of spotted ratfish Hydrolagus colliei in Puget Sound, WA, USA. Densities of large ratfish (≥30 cm) were higher at the deepest depths trawled (70 m) during daylight hours, whereas densities were similar across depth zones (to 10 m) at night. Acoustic tracking of ratfish showed distinct diel patterns of movement and activity level; ratfish moved into shallow, nearshore habitats at night from deeper, offshore habitats during the day and made ~3 times more moves at night than day in shallow habitats. Broader spatial patterns depended on where ratfish were tagged: one tag group remained in one general location with few excursions, whereas a second tag group moved within a 20-km band with some individuals moving >90 km. These data will help inform food web models’ abilities to quantify interspecific interactions between ratfish and other components of their community.     

Factor analysis of trace-element data from tree-bark samples in The Netherlands

Monte Carlo-assisted factor analysis has been applied to a data set of 20 trace-element concentrations in tree-bark samples obtained from 123 locations in The Netherlands, with the aim to investigate the suitability of bark as a biomonitor for air pollution. A Monte Carlo approach was used to give more insight to the uncertainties and significance levels of the factor analysis results. Notwith-standing a rather strong influence of soil material on the concentration levels, factor analysis enabled the identification of five significant pollution source types, all of which corresponded with source types found in an earlier biomonitoring study in The Netherlands using epiphytic lichens. A more detailed comparison with the lichen results showed a remarkable difference in lead concentrations between bark and lichen. It was concluded that bark can be successfully employed as a biomonitor for air pollution. The power of factor analysis to adequately determine the soil contribution may render extensive sample washing procedures superfluous.     

Risk assessment of water pollutants

The sources of toxic xenobiotics and different factors such as ecological diversity, differences in comparative anatomy, physiology and biochemistry, food chain variation, interrelationship within species and life span, etc., are considered during risk assessment of pollutants, and their impact on aquatic ecotoxicology is identified. A fugacity and multimedia compartment model is suggested, based on toxicodynamic (toxicity of the chemical) and toxicokinetic (metabolism of the chemical) considerations to predict and screen the behaviour of pollutants quantitatively in the aquatic environment. The significance of the risk analysis approach in anticipatory actions and regulation of pollution levels is discussed.     

Der deutsch-britisch-französische Höchstflußreaktor in Grenoble und sein Forschungsprogramm

The 57-MW high-flux reactor of the Institute Max von Laue-Paul Langevin at Grenoble serves as a central neutron-beam facility for laboratories and research institutes in the three member countries, the United Kingdom, France, and the Federal Republic of Germany. The heavy-water-moderated and -cooled reactor is equipped with hot, thermal, and cold moderators, providing neutrons with high intensity over an unusual wide range of energies (wavelengths) extending from some 0.1 meV (30 Å) up to some 500 meV (0.4 Å). An extensive system of neutron guides with different curvatures permits the transport of neutrons over distances ranging up to 140 m with minimal intensity losses for neutrons in the useful wavelength band. The transmitted beams, in addition, exhibit very low background contamination by fast and epithermal neutrons, and γ-radiation. A large variety of high-resolution neutron spectrometers provide unique opportunities in fields such as nuclear physics, crystallography, solid-state physics, chemistry, metallurgy, and biology.     

The electromotor system of Torpedo

The electric organ of Torpedo, besides providing abundant amounts of cholinoceptive post-synaptic membrane for the isolation of the acetylcholine receptor protein, is a rich source of cholinergic nerve terminals. Using perfused, innervated tissue blocks from which synaptic vesicles in different functional states can be isolated, much information can be obtained about synaptic-vesicle dynamics. So far this is consistent with the view that the synaptic vesicles are the source of transmitter released on stimulation and that uptake of newly synthesized transmitter by the vesicles is dependent on their having discharged their previous charge of transmitter in at least one cycle of exo- and endocytosis. Studies of the protein composition of the vesicle membrane, especially when combined with similar information about the external presynaptic membrane, purified samples of which are now available from synaptosome (T-sac) preparations, promise to throw new light on the molecular mechanism underlying vesicle exo-/endocytosis.