bluuebunny/crossref_metadata_2025 huggingface dataset:
Ecological implications of the analysis of the redox system of organic matter in the streams of vizcaya (Northern Spain)
Authors: de Bikuña Begoña G. , Docampo Luis
Published: February 2007

Eleven physicochemical variables (pH, temperature, oxygen, percentage of oxygen saturation, orthophosphate, nitrite, nitrate, ammonium, orthosilicate, organic matter and organic matter in sediment) have been analysed in 175 sampling sites during four seasons in 1985. A principal component analysis has been applied after standardization of the density function of the variables, according to skewness and kurtosis. Four main groups of sites have been differentiated. These groups represent different degrees in the redox process of organic matter. (A) Very oxygenated sites with high pH values indicating that the mineralization process prevails. Organic matter appears in low concentrations and a reduced state. (B) Sites nutrient enrichment where elements with high oxidation number prevail (nitrite, nitrate, and orthophosphate). (C) Sites supporting high organic pollution. (D) Sites subjected to heavy urban and/or industrial dumping.
Effect of two temperature regimes from a deep and a surface water release on early development of salmonids
Authors: Grande Magne , Andersen Sigbjørn
Published: February 2007

In order to test the effect of regulated water temperature on the development of eggs and alevins of three salmonid species, deep and surface water from an oligotrophic lake was pumped into a hatchery. Atlantic salmon (Salmo salar) clearly needed the highest number of degree‐days to reach the different developmental stages while brown trout (Salmo trutta) needed just a little more than the brook trout (Salvelinus fontinalis). Eggs and alevins developed in the surface water, which was colder in winter, needed a lower number of degree‐days to reach the hatch and swim‐up stages. In spite of this there was a considerable difference in time for hatching and start of feeding of fish in the two temperature regimes. This might have consequences for the reproduction success and competition between species in regulated rivers.
Off‐river storages as sources and sinks for environmental contaminants
Authors: Higgins Roger J.
Published: February 2007

Off‐river storages accept water from their adjacent stream, often when streamflow is high, and may return water to the stream when streamflow is low. In addition, off‐river storages usually have a water catchment of their own, independent of the main stream, which may contribute a significant proportion of inflow to the storage in total or on some occasions. Off‐river storages have many uses including water supply and flood mitigation, and can also be a significant resource in their own right.

In the same manner that off‐river storages receive, hold, and subsequently discharge water flow, so contaminants contained in the water column may be received, held, and released. However, the timescale of contaminant retention and release may be quite different from that applying to water flows. Also physical, chemical and biological processes in the storage may alter the nature of the contaminants, such that released materials have different environmental implications from those input. This paper presents a discussion of the role of off‐river storages in contaminant movement and distribution in a river reach, and a framework for assessing the influence of these storages on the riverine environment. Case‐study data from the Fly River catchment in Papua New Guinea is then examined in this framework.
The use of non‐persistent herbicides, glyphosate, and 2,4‐D amine, to control riparian stands of Japanese knotweed (reynoutria japonica houtt.)
Authors: Beerlin D. J.
Published: February 2007

The non‐persistent herbicides glyphosate and 2,4‐D amine were applied to riparian stands of R. japonica on the banks of the River Cynon, South Wales at doses of 2154 g and 2790 g active ingredient (a.i.) ha−1 respectively. Glyphosate being tested with one or two applications per season, 2,4‐D amine with two only. Two weeks after spraying, the biomass and leaf area ratio of shoots in all treated plots was depressed but was significantly (P < 0–01) lower in the 2,4‐D amine plots. Ten weeks after treatment shoots had begun to recover but the biomass was still < 40 per cent of the control areas. Rapid (six weeks after treatment) recovery of Leaf Area Ratio was also observed. Second applications of glyphosate and 2,4‐D amine to the respective plots resulted in shoot death after four weeks. Management recommendations are made for the control of R. japonica on riverbanks based on the results presented.
Numerical simulation of overbank flood discharges
Authors: Williams J. J. R. , Stavropoulou Constantina
Published: February 2007

A full computer based investigation of the factors influencing the modelling of overbank flood discharges has been carried out. Several floods of differing magnitudes and peak curvatures were routed down regular channels using an implicit finite difference scheme and the influence of time and distance steps used for the numerical solution of the flow equations were investigated.

Spillage over sharp crested weirs was assumed to satisfactorily simulate the overbank flood discharge; the importance of a correct estimation of the coefficient of discharge was also checked. It was shown that sensibly chosen values of the time step had little effect on the simulations. This was also true for the value of the coefficient of discharge when the sideweir flow was predominately drowned, but not for free flow conditions. It was also shown that close spacing of computational nodes was required at the onset of overbank flow to accurately simulate the overflow and also model the occurrence of large water level gradients.
Vegetation change in the spray zone of a waterfall following river regulation in aurland, Western Norway
Authors: Odland Arvid , Birks Hilary H. , Botnen Astri , Tønsberg Tor , Vevle Odd
Published: February 2007

A 25 m long transect was positioned along the spray gradient of a waterfall (880 m a.s.l.) in the Aurland River, western Norway. The vegetational composition in contiguous 1 m × 1 m quadrats was recorded in 1968 before regulation of the river, and again 20 years later. Spray precipitation, temperature, and humidity were also measured. The 92 per cent reduction in mean annual discharge of the river has resulted in a 98‐100 per cent reduction in spray precipitation along the transect. In general, there has been a great decrease in hygrophilous bryophytes and alpine vascular plants, and an increase in lichens and drought‐tolerant bryophytes. At the end of the transect furthest from the waterfall, which previously received less than 1200 mm of spray precipitation per year, there has only been minor floristic change. Similarly, in the nearest 5 quadrats, where spray precipitation is still substantial, there has been little change in the vegetation. The greatest change occurred in the middle of the transect which formerly received substantial amounts of spray, but is now almost dry.
The impact of river regulation on the lotic macroinvertebrate communities of the lower rhǒne, France
Authors: Fruget J. F.
Published: February 2007

Channelization and the construction of 12 dams on the Lower Rhǒne during the last 30 years increased the morphological and biological effects of 19th century embanking along the river. These trends were demonstrated on the main channel, i.e. the central axis of the alluvial floodplain, by the synchronic study of the benthic macrofauna of six lowhead hydroelectric impoundments.

The variability of the most significant taxa was investigated by an ANOVA, and the data‐samples matrix was processed with a Principal Components Analysis in order to analyse the communities organization and their significance. The benthic macroinvertebrate communities of the channel include some lentic potamic species topographically related with this kind of river (metapotamon), as well as eurytopic and pollution‐tolerant species. Thus, the Lower Rhǒne has become a slow potamic river, in the same way as other large mid‐European rivers. Flow velocity appears to be the most important structural factor in a large regulated river. The homogeneity of the macroinvertebrate communities and the absence of longitudinal typology show that, in a very intensely regulated river, the River Continuum Concept is too theoretical, and the disturbing effects of dams on longitudinal changes and species response to regulation must be taken into account.
Water mollusc communities and bioindication of lower salzach floodplain waters
Authors: Foeckler Francis , Diepolder Uschi , Deichner Oskar
Published: February 2007

The lower Salzach River lost its natural river dynamics as a result of channelization, which caused its bed to deepen, its groundwater table to be lowered, and its floodplains to gradually dry out. These changes of the floodplain have lead to a loss of natural biotopes with their biocoenoses. By using water mollusc communities as bioindicators these losses are detectable at a landscape level. A numerical analysis of a water mollusc survey in 1989 defined six water mollusc communities identifying six water‐body types: three flowing (streams, ditches, and rivers) and three standing (young former meanders, large deep groundwater‐influenced backwaters and small shallow groundwater‐influenced backwaters) within the lower Salzach valley. These communities and water‐body types are interpreted using results from water mollusc communities of other floodplain systems and by comparison with earlier water mollusc surveys in the lower Salzach valley. Then predictions are made on the future fate of the investigated floodplain water. Finally the investigated water bodies are evaluated for nature conservation in the face of plans to impound the lower Salzach River.
Coarse woody debris in stream channels in relation to river channel management in woodland areas
Authors: Gregory K. J. , Davis R. J.
Published: February 2007

Although river channel management now generally uses soft rather than hard engineering techniques the considerable research achieved for woodland river channels has not been completely collated with reference to management implications. Research results from 22 research papers show how debris dams have a significant influence upon the morphological, the process and the ecological aspects of channels; vary in their permanence, and differ in stability according to the overall organic matter budget. A summary diagram contrasts the impact of dams on river channel morphology, process and ecology before and after dam removal. Four major types of specific recommendation about the management of channels in woodland areas are identified from 29 research papers are that (1) management should be undertaken against a background knowledge of the behaviour of coarse, woody debris under natural conditions and that the organic matter budget should be disturbed as little as possible; (2) logging operations should minimize the amount of disturbance to, and disruption of, channel processes; (3) management should optimize the maintenance of habitat diversity and minimize the ecological disturbance to the channel; (4) in some areas specific management practices may require the introduction of new material into the channel. These recommendations are applied to the New Forest, southern U.K., which has a long history of clearance and management of coarse woody debris and where the requirements for clearance in relation to fish, drainage, and aesthetic impact can be achieved by minimizing the amount of removal of material from the river channel. In managing channels with debris dams in woodland areas, it is desirable to work with the river in a holistic basin context.
Discontinuities in the distribution of invertebrates in impounded south island rivers, New Zealand
Authors: Harding Jon S.
Published: February 2007

The invertebrate fauna of 10 river systems, five with impoundments and five without, were sampled. No significant difference was found either in taxonomic richness or invertebrate densities between impounded and unimpounded sites at similar positions along river continua. However, plecopteran species richness was significantly lower and plecopteran density reduced in post‐impoundment sites. Densities of Deleatidium spp. (Ephemeroptera: Leptephlebiidae) were significantly lower at lake outlets compared with other sites. Two species of Zelandobius (Plecoptera: Gripopterygidae) and Eriopterini (Diptera: Tipulidae) snowed distributions apparently curtailed by impoundments, whereas Potamopyrgus antipodarum (Mollusca: Hydrobiidae) had an extended distribution. Margalef's, Menhinick's, Berger‐Parker and Shannon indices, total taxa present and plecopteran taxa were plotted against stream order, stream width and distance from the source. Menhinick's and Shannon‐Weaver indices produced statistically significant but weak regressions, and discontinuity distances and intensity could not be accurately calculated. The usefulness of diversity indices as a measure of the magnitude of impoundment effects in the South Island seems to be limited.
Hydromorphological consequences of regulating the lower vistula, Poland
Authors: Babiński Zygmunt
Published: February 2007

Quantitative and qualitative data on channel changes along the lower Vistula arising from regulation works carried out in the 19th and 20th centuries are presented. Channel width was reduced by 50% and the bed lowered by 1.3 m. Changes of the river's hydrodynamic conditions in the segment from Wloclawek to Swiecie during the last 140 years are discussed. Changes of the bed load balance are characterized.
Effects of water transfer on aquatic insects in a stream in Hong Kong
Authors: Dudgeon David
Published: February 2007

Hong Kong streams serve as indirect catchments for storage reservoirs to which they are connected by a network of undergound tunnels. Water transfer to reservoirs reduces stream flow downstream of the extraction point, and surface flows may disappear in affected reaches during the dry season. The ecological effects of periodic dewatering on aquatic insects were investigated in Tai Po Kau Forest Stream, Hong Kong, where water extraction at a weir gives rise to intermittent flow immediately downstream of a well studied perennial stream section. Benthic samples were taken from the intermittent reach on 48 occasions over a two year period encompassing two dry seasons. Trends in total population densities were unclear, with considerable fluctuations over the study period. In contrast, species richness declined markedly after surface flow disappeared, reaching the lowest values at the end of both dry seasons. A rapid increase accompanied flow resumption on the onset of the summer monsoon, and maximum wet season values were up to five times greater than species richness during the dry season. Dry season declines in Ephemeroptera and Trichoptera were accompanied by a dramatic increase in Coleoptera (Elmidae and especially Helodidae). The situation was reversed during the wet season when Trichoptera (especially Cheumatopsyche and Chimarra) and Ephemeroptera (Leptophlebiidae, Baetidae and Heptageniidae) were numerous. Community structure in the intermittent reach recovered quickly from the dewatering disturbance, due largely to recolonization by drifting animals. At the scale investigated, the community was resilient to disturbance because a source of mobile colonists was available upstream. However, if dewatering affects reaches far downstream, the presence of suitable colonists in upstream reaches cannot be guaranteed, and recovery from disturbance will be delayed. Lowland streams in Hong Kong are often polluted and host to exotic species; in such circumstances the effects of water transfers are exacerbated and recolonization is hindered.
Mussels: The forgotten fauna of regulated rivers. A case study of the Caney Fork River
Authors: Layzer James B. , Gordon Mark E. , Anderson Robert M.
Published: February 2007

During the past century freshwater mussel populations have declined precipitously throughout North America. Much of this loss has resulted from the construction of dams. In the Cumberland River system, 23% (22 species) of the historic mussel fauna is extinct or listed as endangered. Several additional species have either been extirpated from the Cumberland River or exist only in small, non‐reproducing populations. Mussels of headwater streams have been severely affected by coal mining and poor land use practices. An intensive survey was conducted in the Caney Fork River, a major tributary to the Cumberland River, to determine the historic and extant mussel fauna. The results indicate that at least 37 species of mussels have been extirpated from the Caney Fork River, mainly as a result of the construction and operation of the Center Hill Dam. Among the species extirpated, two are now extinct, five are endangered and five are candidates for listing as threatened or endangered. Effects associated with this dam include the inundation of 102 km of riverine habitat, the discharge of hypolimnetic water (which limits mussel reproduction) and an alternating pattern of stream bed scouring and dewatering. The recognition of mussel life history requirements during preconstruction could have reduced many of these effects.
Assessing the ecological effects of groundwater abstraction on chalk streams: Three examples from Eastern England
Authors: Bickerton Melanie , Petts Geoffrey , Armitage Patrick , Castella Emmanuel
Published: February 2007

The invertebrate communities and environmental characteristics of three English chalk streams; the rivers Wissey, Rhee and Pang, were investigated to determine the effects of groundwater abstraction. The data were collected as part of a larger study of 21 UK rivers subject to a variety of types of abstraction. A variety of analytical techniques, including a novel multivariate analysis (co‐structure analysis), and the use of species profiles, showed significant physical and biotic differences between the three rivers and between impacted and natural sites on each river. The observed faunal differences are discussed in relation to existing data on the impact of natural droughts on chalk streams, and the problems associated with determining the effects of non‐point source abstractions (such as from groundwater) are considered.
Stocking strategy for the rehabilitation of a regulated brown trout (Salmo Trutta L.) river
Authors: Aass Per
Published: February 2007

Regulation of the catchment area of the Norwegian river Gudbrandsdalslågen began in 1919. The lowermost power station on the main river was completed in 1964 and is situated about 10 km above the large Norwegian lake, Mjøsa. The lake is the foraging area of the Hunder strain of brown trout, the fastest growing of all Norwegian trout. The running of the power plant has led to a severe reduction in water flows below the dam, and the most important spawning and nursery areas of the Hunder strain has been affected. The natural smolt production has been permanently reduced. The rehabilitation programme has included the construction of a fish ladder through the dam and a fixed minimum flow. A hatchery was built and a stocking programme using the local strain was implemented. The effect of stocking has been the easiest of the relief measures to evaluate. Hatchery reared fish constitute a growing share of the spawning population. During the last three years their share has been close to 60%. Reared fish constitute 30–40% of the trout caught in Lake Mjøsa. The average and best returns of tagged groups have been 25 and 50%, respectively, but return rates are highly dependent on release length and time and place of stocking.
Channel changes associated with two adjacent weirs on a regulated lowland alluvial river
Authors: Thoms M. C. , Walker K. F.
Published: February 2007

Survey data from 1906 and 1988 for the lower River Murray, Australia, reveal changes in channel morphology associated with the construction of Locks 2 and 3 (1925–8), which form contiguous pools in the Valley and Gorge sections, respectively. Regulated annual flows are less than half the volume of natural flows, and the frequency of maximum flows has decreased. Upstream weirs have reduced the sediment supply to the study reach by 1.05 × 106 tonnes per annum. The trap efficiencies of Pools 2 and 3 from 1906 to 1988 were 8 and 13% respectively, with retention channel of 80723 and 267470 tonnes. Responses over the past 60–70 years have differed between the pools‐some channel characteristics have attained a new dynamic equilibrium and others have not. In Pool 3 the average bed slope has been reduced by 000004 (44%) and has attained equilibrium, but in Pool 2 the supply and redistribution of sediment have not been sufficient to reduce the bed slope. There are continuous areas of degradation and aggradation in Pool 3 but discontinuous areas in Pool 2, reflecting different stages in slope adjustment. Cross‐sections have become wider and shallower in Pool 3 but narrower and deeper in Pool 2. These adjustments are influenced by local boundary conditions, floodplain morphology and the position of the study reach in the sequence of weirs. In general, the situation in the lower Murray does not conform to conventional models of the impact of regulation, which are based on data from upland dams. The Murray's gross morphology remains as a relict of the natural, semi‐arid regime. Low contemporary stream energies and cohesive bank materials restrict the initiation of channel metamorphosis and prolong the time required for the completion of channel adjustment.
Effects of atmospheric exposure on chlorophyll a, biomass and productivity of the epilithon of a tailwater river
Authors: Angradi Ted R. , Kubly Dennis M.
Published: February 2007

Field experiments were conducted to determine the effects of atmospheric exposure on the chlorophyll a content, biomass and gross primary productivity (GPP) of littoral epilithon in the Colorado River below Glen Canyon Dam, Arizona. The chlorophyll a content of the epilithon was much more sensitive to exposure than the biomass. The epilithon was rapidly bleached during summer daytime exposures, but algal filaments remained attached for several weeks after reinundation. The percentage of initial chlorophyll a remaining after one day of exposure was not different from the percentage remaining after two days of exposure. However, significant reductions in chlorophyll a content were detected for daytime exposures as short as six hours. Overall, there were close inverse relationships (r2 ≥ 0–73) between the time exposed or cumulative solar radiation (400–700 nm) and the percentage of initial chlorophyll a remaining after reinundation. The GPP of Cladophora glomerata‐dommaled epilithon from the permanently inundated channel was 10 times higher than the GPP of epilithon from the zone of daily water level fluctuation. Experimental atmospheric exposure of the epilithon from each zone reduced the GPP, but not the assimilation ratio (GPP per unit of chlorophyll a) of the epilithon.

The Glen Canyon epilithon has low resistance to exposure disturbances, and recolonization is slow under hydropower peaking flow regimes. Cladophora glomerata has an important structural role in Glen Canyon, the disruption of which is likely to precipitate effects at higher trophic levels.
Nature, mass and preferential sites of coarse woody debris deposits in the lower ain valley (Mollon reach), France
Authors: Piegay Herve
Published: February 2007

Coarse woody debris (CWD) has been examined in a section of the Ain, a sixth order piedmont river with an actively meandering channel and a wooded floodplain. The spatial distribution of CWD, its mass and forms of accumulation are controlled by the hydrodynamics and the retention capacity of the forest. A typology shows the relative importance of woody debris in the mosaic of patches and the essential role of the ecotonal zones. The mass of debris varies from 0001 t ha−1, to more than 200t ha−1, but is lower than those observed in certain American rivers. Most of the material is deposited in the margins and forms a narrow debris line.

The restocking in woody debris is recent in Europe and tends to diversify the environment. This affects the researcher and the planner. The first considers this transit of material as a useful hydromorphodynamic and biodynamic tool which is easy to evaluate, and the second considers it as a restoring and generative vector, the ecological functions of which are recognized. Its effect is stronger today as the watershed area tends to be subjected to a decrease in agricultural activity.
Near‐substrate hydraulic conditions under artificial floods from peaking hydropower operation: A preliminary analysis of disturbance intensity and duration
Authors: Gore James A. , Niemela Scott , Resh Vincent H. , Statzner Bernhard
Published: February 2007

FST hemispheres of identical size but varying density were used to evaluate the intensity and duration of near‐bottom shear stresses during peaking hydropower floods of various magnitudes (maximum 345 m3 s−1; baseflow 2.75 m3 s−1). The FST values at single points were recorded at rapid intervals along previously surveyed transects during the rising limb of flood events at various distances from the hydropower facility. Whole transect evaluations were ‐accomplished after the ‘flood’ level had stabilized.

Measurements of over 1300 FST values were significantly correlated with mean water column velocity and complex hydraulic conditions such as turbulence, shear velocity and viscous sublayer. FST hemispheres are a rapid means of characterizing hydraulic conditions in medium order rivers. Changes in near‐substrate hydraulic conditions were patchy and could be classified in terms of risk to fauna of either dislodgement or physical damage. Low risk (class 1) changes occurred when FST values increased rapidly but returned to initial values after a short period of time (< 90 minutes) from the arrival of the peaking wave. Medium risk (class 2) changes occurred when FST values increased rapidly and decreased after a short period of time, but remained at levels higher than before the arrival of the flood wave. High risk (class 3) changes occurred when FST values increased rapidly and remained at high levels during the entire flood event.

It is suggested that floods that do not initiate significant bed movement create a mosaic of patches of variable disturbance risk to benthic fauna. Rapid evaluation by FST hemispheres could be used to characterize the overall disturbance potential for the channel by the construction of a weighted index based on the frequency of the various risk classes occurring in the reach being evaluated. A more appropriate analysis of impacts of peaking hydropower and other flood events must include the existence of hydraulic refugia and the movement patterns of both benthic species and those species that occupy the water column.
The fish ladder at the itaipu binational hydroelectric complex on the paraná river, Brazil
Authors: Borghetti J. R. , Nogueira V. S. G. , Borghetti N. R. B. , Canzi C.
Published: February 2007

A study was carried out from 23 October to 19 November 1992 to determine the ability of fish to ascend the fish ladder at the ITAIPU dam, to identify the species attracted and to evaluate possible fish selection. The results show that some species of fish can ascend the ladder during the migratory period; the dam is non‐selective with respect to species, but selective with respect to fish size as a result of the presence of reduced openings. The ladder was ascended by both scaly species from surface waters (agile movers) and by deep water species which were characterized by slow movements. An average of 2892 fish ascended the ladder each day. The weight and length of fish recorded ranged from 336.0 to 3676.0 g and from 30.2 to 71.3 cm, respectively. The largest group of migrating fish was the curimba (Prochilodus scrofa). The high ratio of 72% of fish in the gonadal development stage, classified as ‘maturing’, indicates that the species caught in the ladder were migrating for reproduction purposes.
Downstream effects of a new hydropower impoundment on macrophyte, macroinvertebrate and fish communities
Authors: De Jalon Diego Garcia , Sanchez Pablo , Camargo Julio A.
Published: February 2007

The downstream effects of Valparaíso Reservoir (Río Tera, north‐western Spain) on macrophyte, macroinvertebrate and fish communities are examined by comparing their respective structures before (1986) and after (1990‐1991) the creation of this hydropower impoundment. A single sampling station was selected 2.4 km below the dam. Macrophytes significantly (p < 0.05) decreased their total biomass, although the species composition remained dominated by two species (Myriophyllum verticillatum and Ranunculus fluitans). The macroinvertebrate community, on the other hand, exhibited a significant (p < 0.05) decrease in taxonomic richness, total density and total biomass. In general, planarians, ephemer‐opterans, coleopterans, plecopterans and trichopterans disappeared or decreased their abundances. Scrapers (as relative biomass) were the functional feeding group most adversely affected by the new flow regulation. With regard to the fish community, the most significant change was the absence of all resident coarse fishes (cyprinids, primarily) at the sampling site during the 1990 and 1991 sampling surveys. Conversely, salmonids (Salmo trutta) persisted; the trout population was dominated by individuals of the 0+ age group (⩽ 1 year old) both before and after the construction of Valparaíso Dam. It is concluded that short‐term flow fluctuations induced by hydroelectric power generation were the main factor causing the observed adverse effects. In this respect, some management measures to minimize these effects are recommended.
Origin and abundance of lake whitefish (Coregonus clupeaformis) congregating below a hydroelectric control dam in northern Canada
Authors: Barnes N. E. , Bodaly R. A.
Published: February 2007

The abundance and origin of lake whitefish (Coregonus clupeaformis) congregating downstream of the Missi Falls control dam at the outlet of Southern Indian Lake (SIL) in northern Manitoba, Canada were studied during two successive open water seasons. In 1986 the number of lake whitefish below the dam increased to almost 90000 in the autumn and most of these fish were physiologically ready to spawn. Morphological comparisons indicated that most of these fish originated from SIL and were apparently attempting to return to it. Flows through the dam in this year were high and similar to those before the diversion of the Churchill River. In 1987 there were fewer fish of SIL origin below the control dam and the numbers decreased over the summer. Discharge through the dam was much lower in 1987 than before diversion. The number of lake whitefish below the dam that appeared to originate from lakes downstream of Missi Falls on the lower Churchill River varied from 2000 to 12000 over the whole study period. These fish may have been attracted to the control dam by local environmental conditions such as cool water temperatures. The effects of the control dam on lake whitefish movements and distribution was not predicted despite extensive pre‐project studies. These effects should receive more attention in the prediction of impacts of boreal hydroelectric projects.
Improving surface‐analysis methods for characterization of advanced materials by development of standards, reference data, and interlaboratory comparisons
Authors: Baer D. R.
Published: February 2007

This paper summarizes the results of two surveys examining current needs for improved analyses of surfaces. Surfaces and interfaces are increasingly important to science and technologies associated with nanoparticles, nano‐structured materials and other complex materials including those associated with information systems and medical or biological applications. Adequate characterization of advanced materials frequently requires application of more than one analysis method along with the need to analyze data in increasingly sophisticated and sometimes interrelated ways. It is useful for both new and experienced analysts to have ready access to best practices for obtaining accurate and useful information from a variety of different analysis tools. The International Organization for Standardization (ISO) Committee TC 201 on surface chemical analysis and the ASTM Committee E‐42 on surface analysis are working to address these needs by assembling guides and standards reflecting the collective experience and wisdom of experts in this community. Published in 2007 by John Wiley & Sons, Ltd
A database approach for information communication in a peer‐to‐peer collaborative CAD environment
Authors: Ma Haoxue , Risch Tore
Published: February 2007

Timely and efficient information communication is a key factor in ensuring successful collaboration in engineering collaborative design. This work proposes a database approach to support information communication between distributed and autonomous CAD systems. It provides the designer with an easy and flexible way, a project‐based propagation meta‐table, to specify what parts of a CAD information model should be communicated to other collaborating designers. A CAD peer manager, containing a peer database that stores information to be exchanged with the other collaborators, wraps each participating CAD system. The peer manager identifies changes made to the CAD model by using stored procedures and active rules in the peer database that are automatically generated based on the propagation meta‐table. The identified updates are propagated in a timely manner to other peers via inter‐database message passing, thereby minimizing the volume of necessary information to be exchanged. Furthermore, remote peer designers can flexibly incorporate, filter, or delete received updates by using a propagation control interface, which is also used to issue user's commands to download the data from the CAD system to the peer database and lookup the received messages in the peer database. The approach is applicable on any CAD system having a CORBA interface and can also be applied to other kinds of object‐oriented interfaces. Copyright © 2007 John Wiley & Sons, Ltd.
Influence of Cu2+‐organic montmorillonites on thermal decomposition and smoke emission of poly(vinyl chloride) by cone calorimetric study
Authors: Yang Zhihua , Li Bin , Tang Fei
Published: February 2007

Cu2+‐Organic montmorillonites were prepared by modifying Na+ montmorillonite (Na+‐MMT) with silane coupling agents and cupric sulfate. PVC/organic montmorillonite composites were prepared by the melt intercalation method. Morphological structure of modified MMT and PVC/MMT was obtained by using XRD and SEM. The XRD results showed that silanes and Cu2+ were intercalated among interlayers and that modified MMT may have exfoliated dispersion in PVC. Effects of Cu2+‐organic montmorillonites on decomposition and smoke emission of poly(vinyl chloride) (PVC) in the flaming mode were investigated by using a cone calorimeter at an incident heat flux of 25 kW·m−2. Cone experimental data demonstrated that the Cu2+‐organic montmorillonites prepared were new effective smoke suppressants. They clearly promoted an early HCl elimination, crosslinking reactions, and char residue formation, based upon the decomposition parameters of mass loss, mass loss rate, and time of initial decomposition (tinitial). Cu2+‐Organic montmorillonites decreased peak heat release rate, total heat release, peak smoke production rate, total smoke production, and smoke extinction area during the flaming process. The smoke‐reducing efficiency of Cu2+‐organic montmorillonites (Cu2+‐OMMTs) was the best. However, the content of cupric ion was only 0.6–0.8% in Cu2+‐OMMTs and 0.03–0.04% in PVC composites. They may make the smoke‐reducing efficiency reach 45–50%. This result further demonstrates that Cu2+ ion is a very effective smoke suppressant for PVC. J. VINYL ADDIT. TECHNOL., 13:31–39, 2007. © 2007 Society of Plastics Engineers.
Hydrothermal Synthesis, Structure and Property of a Zinc Coordination Polymer Based on Aromatic Polycarboxylate and Phenanthroline Ligands
Authors: Yu Xiao‐Yang , Lu Jing , Yu Jie‐Hui , Zhang Xiao , Xu Ji‐Qing
Published: February 2007

A zinc coordination polymer [Zn(μ2‐H2bta)1/2(μ4H2bta)1/2(phen)(H2O)]n (1) (H4bta = benzene‐1,2,4,5‐tetracarboxylic acid, phen = 1, 10‐phenanthroline) has been hydrothermally synthesized and characterized by elemental analysis, IR spectroscopy, thermogravimetric and single‐crystal X‐ray diffraction analyses. Compound 1 displays pucker layer structure formed from Zn2+ ions and μ2‐H2bta2− and μ4‐H2bta2− bridging ligands, and it is linked into three dimensional (3D) supramolecular frameworks through the hydrogen bonds and π‐π interactions. It exhibits strong blue fluorescence at room temperature in the solid state.
Hydrothermal Synthesis of a New Vanadium Tellurate(VI) with a Novel Chain Structure: (NH4)4{(VO2)2[Te2O8(OH)2]}·2H2O
Authors: Kim Hyejin , Cho Yoonsuk , Yun Hoseop , Do Junghwan
Published: February 2007

A new ammonium vanadium tellurate, (NH4)4{(VO2)2[Te2O8(OH)2]}·2H2O (1) was hydrothermally synthesized and characterized by elemental analyses, IR spectrum, TG analysis, and single crystal X–ray diffraction. Compound 1 crystallizes in the monoclinic system, space group P21/n, a = 7.3843(15) Å, b = 17.111(3) Å, c = 7.3916(15) Å, β = 118.88(3)°, V = 817.9(3) Å3, Z = 2, R1 (I>2σ(I)) = 0.0235, wR2 (all data) = 0.0462. The structure of 1 consists of infinite anionic chains, {(VO2)2[Te2O8(OH)2]}4− which contain octahedral VO6 and TeO5OH units. Each octahedral VO6 and TeO5OH unit is connected by sharing an edge to form V2O10 and Te2O8(OH)2 binuclear units. The V2O10 and Te2O8(OH)2 binuclear units are alternatively connected to one another, creating complete infinite {(VO2)2[Te2O8(OH)2]}4− chains along the c direction. The anionic chains are separated by ammonium cations and water molecules that link the chains through a network of hydrogen bonds. In addition, the structure contains an extended network of O–H·····O hydrogen bonds between the chains.
LCAT inhibitors interfere with the enzymatic determination of cholesterol and triglycerides
Authors: Harris William S. , Rayford Alan
Published: February 2007

5,5‐Dithiobis‐(2‐nitrobenzoic acid) (DTNB) andp‐chloromercuriphenylsulfonic acid (PCMPS) are well‐known sulfhydryl inhibitors that are used to inhibit lecithin: cholesterol acyltransferase (LCAT). They were each found to interfere with the enzymatic assays of cholesterol and triglycerides. DTNB falsely reduced the measured plasma cholesterol content, and falsely increased triglyceride readings. The inteference with the triglyceride assay could be largely prevented by blanking for glycerol. PCMPS had only a slight effect on the cholesterol assay, but falsely lowered the triglyceride readings to a great extent, even with glycerol‐blanking. Thus, these inhibitors should be avoided when plasma samples are to be enzymatically analyzed for cholesterol or triglycerides.
Incorporation of hormone‐sensitive lipase into phosphatidylcholine vesicles
Authors: Holm Cecilia , Fredrikson Gudrun , Sundler Roger , Belfrage Per
Published: February 2007

Enzymatically active, detergent‐solubilized purified hormone‐sensitive lipase (HSL) was incorporated into phosphatidylcholine (PC) vesicles, using a detergent‐dialysis procedure with small PC vesicles, obtained by sonication, as phospholipid source and CHAPS, a zwitterionic bile‐salt derivative, as detergent. Association of enzyme protein with the PC vesicles was verified by floatation in a discontinuous dextran gradient and by gel chromatography. An average of 35% of added HSL was incorporated into the vesicles. The vesicles were shown, by quasi‐elastic light scattering and electron microscopy, to have a diameter of approximately 160 nm. The vesicleassociated HSL could be phosphorylated by cyclic AMP‐dependent protein kinase. The vesicles were stable, both with regard to enzyme activity and size, for at least 4 days when stored at 4°C. The preparation of detergent‐free, vesicle‐associated and stable HSL provides new possibilities to study some of its properties, and supports and extends the previous report (Holm, C., Fredrikson, G., and Belfrage, P.,J. Biol. Chem. 261, 15659–15661, 1986) which demonstrated the amphiphilic character of HSL.
Uptake and metabolism of dolichol and cholesterol in perfused rat liver
Authors: Kalén A. , Söderberg M. , Elmberger P. G. , Dallner G.
Published: February 2007

The uptake of dolichol and cholesterol by perfused rat liver was studied. When these radioactive lipids were incorporated into egg phosphatidylcholine liposomes, both dolichol and cholesterol appeared initially in the supernatant and in the microsomal fraction and, later on, in the mitochondrial‐lysosomal fraction. The lipids taken up were esterified to some extent, but no phosphorylation of dolichol occurred. Incorporation of dolichol and cholesterol into lipoproteins increased the efficiency of uptake, which was receptor‐mediated in this case. Accumulation of these lipids occurred in lysosomes followed by a transport to the endoplasmic reticulum (ER). Both labeled dolichol and cholesterol appeared in the bile. In the case of dolichol, the majority of this radioactivity was not associated with the original substance itself, and probably represented lipid‐soluble catabolites. In the case of cholesterol, most of the radioactivity was associated with bile acids. It appears that, in contrast to the receptor‐mediated uptake of lipoproteins from the perfusate, the uptake of liposomal lipids involves a different mechanism. After association with the plasma membrane, the lipids enter into the cytoplasm and are transported to the ER and later to the lysosomes.
Synergistic activation of CTP:phosphocholine cytidylyltransferase by phosphatidylethanolamine and oleic acid
Authors: Sleight Richard G. , Thi Dao Hong‐Ngoc
Published: February 2007

CTP:phosphocholine cytidylyltransferase present in rat liver cytosol was activated almost 30‐fold when assayed in the presence of liposomes containing 60 mole % dioleoyl phosphatidylethanolamine (DOPE). During the assay, some of the DOPE was degraded to lysoPE and oleic acid. Whereas cytidylyltransferase activity was not affected when assayed in the presence of liposomes containing lysoPE, liposomes containing oleic acid activated the enzyme. Activation by oleic acid could be eliminated by the addition of fatty acid‐free bovine serum albumin (BSA) to the assay. When cytidylyltransferase activity was measured in the presence of both BSA and liposomes containing DOPE, enzyme activity was increased almost 20‐fold, as compared with assays performed in the absence of added lipid. The 1.5‐fold difference in cytidylyltransferase activity observed when cytosol was assayed with DOPE containing liposomes in the absence or presence of BSA (30‐fold stimulation vs 20‐fold stimulation) cannot be explained by the loss of activation attributable to oleic acid alone. Activation of the enzyme in the presence of liposomes containing DOPE and oleic acid is several‐fold greater than the sum of the activations caused by the individual compounds. These data suggest that PE and oleic acid act synergistically in activating the cytidylyltranferase.
Essentiality of fatty acids
Authors: Spector Arthur A.
Published: February 2007

All fatty acids have important functions, but the term “essential” is applied only to those polyunsaturated fatty acids (PUFA) that are necessary for good health and cannot be completely synthesized in the body. The need for arachidonic acid, which is utilized for eicosanoid synthesis and is a constituent of membrane phospholipids involved in signal transduction, is the main reason why the n‐6 class of PUFA are essential. Physiological data indicate that n‐3 PUFA also are essential. Although eicosapentaenoic acid also is a substrate for eicosanoid synthesis, docosahexaenoic acid (DHA) is more likely to be the essential n‐3 constituent because it is necessary for optimal visual acuity and neural development. DHA is present in large amounts in the ethanolamine and serine phospholipids, suggesting that its function involves membrane structure. Because the metabolism of n‐6 PUFA is geared primarily to produce arachidonic acid, only small amounts of 22‐carbon n‐6 PUFA are ordinarily formed. Thus, the essentiality of n‐3 PUFA may be due to their ability to supply enough 22‐carbon PUFA for optimal membrane function rather than to a unique biochemical property of DHA.
Identification of vitamin E‐dependent water soluble fluorescent compounds in mouse tissues
Authors: Manwaring John D. , Csallany A. Saari
Published: February 2007

The present paper describes the identification of two vitamin E‐dependent, water soluble fluorescent compounds in mouse tissues. Ultraviolet and fluorescent spectroscopy, derivatization with 1‐dimethylamino‐naphtalene‐5‐sulfonyl chloride (dansyl chloride) and cochromatography using high performance liquid chromatography (HPLC) were utilized for the identification of the unknown compounds. The water soluble fluorescent compounds in mouse tissues were identified as tyrosine and tryptophan. The compounds were previously found to increase significantly in vitamin E deficiency in various tissues.
Autoxidation of polyunsaturated triacylglycerols. III. Synthetic triacylglycerols containing linoleate and linolenate
Authors: Miyashita K. , Frankel E. N. , Neff W. E. , Awl R. A.
Published: February 2007

Four triacylglycerols containing linoleate (L) and linolenate (Ln) in specific positions were synthesized to determine the effect of fatty acid position on their relative rates and products of autoxidation. Analyses by reversedphase high performance liquid chromatography (HPLC) showed that autoxidation of L‐ and Ln‐containing triacylglycerols form monohydroperoxides and hydroperoxy epidioxides as the main products. The peroxyl radicals of internal 12‐ and 13‐mono‐hydroperoxides of Ln triacylglycerol components cyclized rapidly and their relative triacylglycerol position had no influence on their rates of cyclization. A good linear relation was obtained between total HPLC peak areas (detected at 235 nm) of the main oxidation products and peroxide values. Reversed phase HPLC analyses thus provide a useful method to estimate oxidation of polyunsaturated triacylglycerols. The ratios of Ln to L mono‐hydroperoxides were twice the ratios of Ln to L in the triacylglycerol substrates. Ln triacylglycerol components, therefore, oxidized twice as much as the L components. At 40°C, LnLnL oxidized slightly faster than LnLLn with respective induction periods of 45 and 47 hr. LLnL oxidized faster than LLLn with respective induction periods of 56 and 60 hr. Dilinolenoyl‐linoleoylglycerols are, therefore, slightly less stable to oxidation when Ln is in the 1,2‐ than the 1,3‐triacylglycerol position. Dilinoleoyl‐linolenoylglycerols are less stable when L is in the 1,3‐ than the 1,2‐triacylglycerol position.
African American Children's Depressive Symptoms: The Prospective Effects of Neighborhood Disorder, Stressful Life Events, and Parenting
Authors: Natsuaki Misaki N. , Ge Xiaojia , Brody Gene H. , Simons Ronald L. , Gibbons Frederick X. , Cutrona Carolyn E.
Published: February 2007

The prospective effects of observed neighborhood disorder, stressful life events, and parents' engagement in inductive reasoning on adolescents' depressive symptoms were examined using data collected from 777 African American families. Multilevel analyses revealed that stressful life events experienced at age 11 predicted depressive symptoms at age 13. Furthermore, a significant interaction between neighborhood disorder and parents' engagement in inductive reasoning was found, indicating that parental use of inductive reasoning was a protective factor for depressive symptoms particularly for youths living in highly disordered neighborhoods. The importance of examining correlates of depressive symptoms from a contextual framework, focusing on individuals, families, and neighborhood contexts, is emphasized.