bluuebunny/crossref_metadata_2025 huggingface dataset:
Environmental effects of flow regulation on the lower river Murray, Australia
Authors: Walker K. F. , Thoms M. C.
Published: February 2007

Before regulation flows in the lower Murray were highly variable, as for most rivers in semi‐arid regions. Major floods promoted large‐scale recruitment of flora and fauna in riverine and floodplain communities, and seasonal floods maintained lower levels of recruitment. The regime changed with the construction of 10 low‐level weirs in 1922–35, supplemented by the effects of dams in upstream areas. Flows remain variable but are much reduced in volume (about 44%). Low flows (100–300 Gl per month) have decreased five‐fold and moderate flows (500–1500 Gl per month) have increased two‐fold. Although the magnitude of peak seasonal flows has been diminished, the timing of flows is unaffected. The effects differ in the Valley and Gorge sections of the river, depending on local development of the floodplain and associated wetlands. The weirs have flooded once‐temporary wetlands and contributed to problems of salinization. Weir operations cause daily stage fluctuations that diminish downstream, and the channel is developing a stepped gradient as a consequence of active deposition and erosion. Regulation has limited exchanges between the river and its floodplain, changed the nature of the littoral zone and generally created an environment inimical to many native species, notably fish. The key to rehabilitation may be to restore a more natural balance of low and medium flows, but this may be unrealistic given the needs of irrigators and other water users. Despite its evolutionary history of wide spatial and temporal variation, the Murray river‐floodplain ecosystem evidently cannot accommodate these forms of disturbance.
Effects of increased discharge on benthic invertebrates in a regulated river
Authors: Fjellheim Arne , Håvardstun Jarle , Raddum Gunnar G. , Schnell Øyvind A.
Published: February 2007

Benthic animal densities, biomass and production were studied in a weir basin and the upstream adjacent riffle area in a regulated west Norwegian river in 1988 and 1989. In years of normal discharge, such as 1988, water from a large part of the catchment area is transferred to a hydroelectric power station in another watershed, and the discharge at the study site is low. In 1989 heavy precipitation and a mild winter climate caused surplus production of hydroelectric power. Consequently large amounts of stored water had to be released as overflow at the dam. On a yearly basis the discharge at the study site was 4.8 times higher in 1989 than 1988, whereas peak values were 12.0 and 54.0 m3 s−1 in 1988 and 1989, respectively. The change in flow regime resulted in reduced biomass and faunal changes. Biomass was high during 1988 and the first months of 1989. Corresponding to the flow increase in June 1989 the biomass in the weir basin was reduced from 7.1 to 2.2 g dw m 2 and from 8.0 to 0.8 g dw m−2 at the two studied transects. The mean biomass in the autumn period was 270 and 800% higher at the two transects in 1988 compared to 1989. A great part of the biomass reduction was caused by reduced densities of the chironomids Stictochironomus pictulus and Chironomus melanotus. The mean autumnal densities of these two species were reduced from 4400 to 170 ind. m2 and from 876 to 2 ind. m2, respectively. An increase in the biomass was recorded for rheophilic insect larvae, such as the stoneflies Leuctra fusca and Capnia pygmaea. On the other hand lentic caddis larvae such as Apatania spp. and Oxyethira spp. were reduced. Mean benthic animal production of the weir basin was reduced from 22.3 g dw m−2 yr−1 in 1988 to 12.5 g dw m −2 yr−1 in 1989. In a riffle upstream of the weir basin the production was reduced from 9.1 to 3.9 g dw m−2 yr −1 in the same period. The faunal change is explained by an altered physical environment and destruction of lentic habitats.
Effects of river bed restructuring on fish and benthos of a fifth order stream, melk, Austria
Authors: Jungwirth Mathias , Moog Otto , Muhar Susanne
Published: February 2007

Studies conducted on 15 sections of seven different epipotamal streams between 1981 and 1984 established the impact of river bed structures on fish communities. Reduced spatial heterogeneity due to river straightening resulted in decreasing numbers of fish species, stock density and biomass. The variance of maximum depths (VMD) used as a measure of habitat structure showed a highly significant correlation with the number (NFS) and diversity of fish species (DFS). In 1987 these models were used for the evaluation of a planned restructuring project on a channelized section of the Melk River, which was realized in 1988. During a three year investigation of the response of the fish fauna and benthic community to changed hydraulic and morphometric conditions within the restructured river bed section the validity of the VMD/NFS model could be verified. The number offish species increased from 10 to 19. Fish density and biomass as well as annual production of 0+ fish increased three‐fold. In contrast the DFS did not reach expectations, suggesting that more time is needed to establish a balanced fish community. The newly created riparian zones (e.g. shallow water lagoons, pioneer vegetation of gravel banks, etc.) provided important refuge regions during flooding, places for hatching or emerging, and nursery grounds for younger benthic instars and fish fry, indicating the positive effects of a complex water‐land ecotone. Owing to the increasing habitat variability, including riffle‐pool sequences, more and diverse specific benthic communities with many epipotamalic species developed. The number of benthic invertebrate taxa increased from 202 in the channelized section to 273 in the restructured area (in total 347 taxa were recorded). The benthic drift decreased significantly in the restructured river section, suggesting unfavourable conditions for many benthic invertebrates in the straightened section. Terrestrial invertebrates, however, occasionally entering the water body, showed a ten‐fold increase in drift in the channelized reaches.
Research needs in regulated river ecology
Authors: Ward J. V. , Stanford J. A.
Published: February 2007

The general effects of single dams on the downstream ecology of temperature lotic systems are predictable, although some underlying causal mechanisms remain elusive. Few quantitative data of an ecological nature are available for regulated tropical rivers, however, and it would not be prudent to uncritically apply principles and patterns developed from temperate rivers to fluvial systems of the tropics. New techniques of gradient analysis appear especially suited to examining spatial recovery gradients below dams at any latitude and portend to provide considerable insight into the mechanisms responsible for such patterns. Few studies have specifically examined the influence of regulation on interactions between the river channel and the floodplain and virtually nothing is known of channel‐aquifer interactions. A fuller understanding of these interactive pathways is necessary to effectively regulate discharge as part of river restoration strategies. Viewing regulated streams as experimental systems for addressing ecological questions has proved to be useful and should be further exploited. It is concluded that research and expertise in regulated stream ecology will increasingly be needed as the rational basis for flow criteria to conserve, protect and enhance the societal values of regulated rivers world‐wide.
Short communication. Pipelines as a refuge for freshwater snails
Authors: Sheldon F. , Walker K. F.
Published: February 2007

In the lower River Murray, Australia, populations of gastropods have declined markedly over the past 40 years. Of the native fauna of about 18 species, only the ancylid Ferrissia petterdi remains common (but in patches), and another five species feature in sporadic local resurgences. Until recently the viviparid Notopala was thought to be extinct. The introduced physid Physa acuta is widespread, but in low numbers. The decline probably is associated with flow regulation, high turbidity and the introduction of common carp. Snail populations have persisted, however, in irrigation pipelines fed from the river, where they periodically cause blockages. This paper reports the discovery of the only known populaion of Notopala hanleyi in a pipeline where the inner wall accumulates microbial and other organic matter, providing high quality food for snails. In the Murray before regulation most of the periphytic biomass was probably microbial, as fluctuating water levels would have maintained littoral communities in a highly productive, early state of succession his postulated that, by stabilizing seasonal water levels, regulation has promoted the production of filamentous green algae, an inferior food source, and so displaced snail populations from the open aquatic environment.
Implications of the annual macrophyte growth cycle on habitat in rivers
Authors: Hearne John W. , Armitage Patrick D.
Published: February 2007

The continuity equation, Manning's equation and an empirically determined relationship between channel roughness and the biomass of macrophytes were used to simulate the effects of weed growth in contrasting channels. Two indices of wetted available habitat, velocity and depth were chosen to illustrate the role of macrophyte in maintaining and modifying instream habitat with particular reference to chalk streams. Plant growth maintained depth within the channels and its effect was modified by channel shape and slope. Weed cutting resulted in very sudden changes in depth and velocity and the loss of a large volume of water from the river. The results indicate that macrophyte growth could be used to maintain wetted habitat while allowing more abstraction, but more data are required on the long‐term effects of implementing such policies.
Changes in fish communities of the Phongolo floodplain, Zululand (South Africa) before, during and after a severe drought
Authors: Merron Glenn , Bruton Michael , De Lalouviere Philippe La Hausse
Published: February 2007

The Pongolapoort Dam in Zululand, South Africa has regulated the flow of the Phongolo River to its floodplain downstream since 1970. Ecological surveys of the floodplain fish communities were conducted before (1974–6), during (September 1983) and after (August 1984) a severe drought to assess the response of the fish stocks. During the three study periods the floodplain lake communities varied. Fish populations were markedly reduced during the drought. The redistribution offish on the floodplain after the drought was rapid. Colonization of previously dry lakes was mainly by juvenile fish and the mean size of the fish was lower in these lakes than in the refuge lakes. A few species successfully spawned during the drought, although the natural mortality of the young of the year was probably greater due to increased competition and predation in restricted habitats. Large scale spawning in most species occurred immediately after the drought was broken by a large flood.
Fine sediment infiltration into gravel spawning beds within a regulated river experiencing floods: Ecological implications for salmonids
Authors: Sear D. A.
Published: February 2007

Infiltration rates into eight gravel spawning beds were monitored over a range of discharges including compensation flows, peak hydropower generation and floods of up to bankfull capacity. The results indicate that the interrelationship of sediment supply and discharge influence both the rate and grain size composition of infiltrated sediments, with maximum rates experienced during bankfull floods when sediments are scoured from upstream pools. The effects of river regulation for hydropower are shown to produce a finer matrix infill in the absence of unregulated tributary sources, although the rates of infiltration are much lower than for sites downstream of unregulated tributaries. Values for infiltration rates are shown to be detrimental for small salmonid spawning redds during post‐flood conditions when sediment transport is not restrained by supply.
Experimental measurements of river‐bank erosion caused by boat‐generated waves on the gordon river, Tasmania
Authors: Nanson Gerald C. , Von Krusenstierna Axel , Bryant Edward A. , Renilson Martin R.
Published: February 2007

Erosion of natural river banks by boat‐generated waves is an increasingly serious problem on the navigable reaches of many rivers, particularly on the middle and estuarine reaches. An experiment designed to link bank erosion rates with easily measured wave characteristics, conducted on the scenic lower Gordon River in Tasmania, provides information useful for river management. Within a boat‐generated wave train a number of characteristics were measured and most showed a high correlation with measured rates of bank retreat. Maximum wave height within the train is the simplest measure and is associated with a major threshold in erosive energy on unconsolidated sandy alluvium at wave heights of 30 to 35 cm. At maximum wave heights above 35 cm all but the most resistant bank sediments erode. Reducing maximum wave heights to < 30 cm by limiting boat speeds, and reducing the frequency of boat passages, caused a dramatic decline in bank erosion along the river.
Stability of the pool‐riffle sequence in changing river channels
Authors: Gregory K. J. , Gurnell A. M. , Hill C. T. , Tooth S.
Published: February 2007

The pool‐riffle sequence as an important feature of river channels was described by Leopold et al. (1964) to occur with a spacing of five to seven times the channel width. Subsequent work has generally confirmed this spacing, although more closely spaced pools and riffles are quoted for some channels in woodland basins and for some channelized streams. Although few detailed empirical studies have been made of adjustments of the pool‐riffle spacing, a detailed survey of a 6 km channel reach containing over 300 riffles in the New Forest, southern England indicates that despite the influence of woody debris and channelization, the interriffle distance generally falls within the range of five to seven channel widths. As substantial adjustments in channel dimensions have been widely observed downstream of channelization schemes, land‐use changes, and dams and reservoirs, the associated adjustments in pool‐riffle spacing should be a consideration in channel management and an ingredient of design for channel restoration.
Ecological effects of river regulation on mammals and birds: A review
Authors: Nilsson Christer , Dynesius Mats
Published: February 2007

Although most of the world's river systems are regulated, the effects of river regulation on mammals and birds are little known. In fact, speculations are more common than empirical data. A review of this topic is presented, emphasizing northern rivers where most impacts have been described. Effects are related to the major causes of change. It is concluded that the two most disastrous effects of river regulation on mammals and birds are the permanent inundation of vast areas of land, and the disruption of the seasonal flood regime along the river. The design of future investigations to improve our knowledge is considered.
Role of the floodplain and riparian zone in suspended matter and nitrogen retention in the adour river, south‐west France
Authors: Brunet R. C. , Pinay G. , Gazelle F. , Roques L.
Published: February 2007

The retention capacity of the floodplain and riparian zone for suspended matter and nitrogen has been investigated in the Adour River, a seventh order stream in south‐west France. Suspended matter and nitrogen fluxes through a 25 km meandering stretch of the river were measured during two flood events and compared with the amount of sediment trapped in the riparian zone (1.1 km2) and the major floodplain (16.8 km2) of the studied area. It was estimated that the floodplain and the riparian zone together retained between 10 and 20% of the suspended matter entering the stretch under study during the two main floods (138 700 Mg). Moreover, they retained about 11% of the total particulate nitrogen fluxes (640 Mg). Although the riparian zones are 15 times smaller than the major floodplain, the total suspended matter and particulate nitrogen deposition were, 50 and 17 times, respectively, larger in the riparian zone. The results obtained on the Adour River floodplain show that large river systems should not be considered only as export systems as riparian zones can retain a significant amount of suspended organic and mineral matter during floods.
Environmental and biological responses of former channels to river incision: A diachronic study on the upper rhǒne river
Authors: Bornette Gudrun , Heiler Gudrun
Published: February 2007

The impacts of river incision should be a lowering of the river level, which would increase the rate of water flow from the hillslope aquifer to the river and its former channels. If this aquifer is nutrient‐poor, it should favour the oligotrophication of the former channels. However, if the lowering of the water‐table exceeds the depth of the former channels, then it should lead to the drainage of these channels. These hypotheses were tested on two former channels located in a degrading reach of the Rhǒne River (France); the former channels were influenced by floods, seepage water from the river and hillslope groundwater in 1989. The rate of river incision in this reach has increased since 1980 because of gravel extraction from the river bed (0.5 m between 1989 and 1993). Between 1989 and 1993, the reduction of river infiltration and the increase in the amount of water from the hillslope aquifer in the former channels were demonstrated by the decrease in the phosphate and ammonia content of the water, and its increased alkalinity and conductivity. The responses of aquatic vegetation to river incision depended on the vegetation zone investigated. Two floristic zones that were frequently flooded and species‐poor in 1989 remained species‐poor in 1993. Two floristic zones, which were species‐rich and patchily organized, became dry or very shallow in 1993; as a consequence, aquatic vegetation disappeared, and was replaced by helophytes and terrestrial species. In the last vegetation zone, the increase in the amount of water coming from the hillslope aquifer caused the appearance and development of Chara hispida, an oligotraphent species. Unforeseen impacts of river incision were a decrease in the spatial and temporal heterogeneity of the former channels and lower aquatic macrophyte richness.
Effects of glen canyon dam on colorado river sand deposits used as campsites in grand canyon national park, USA
Authors: Kearsley Lisa H. , Schmidt John C. , Warren Katherine D.
Published: February 2007

Glen Canyon Dam, located on the Colorado River 24km upstream from Grand Canyon National Park, has affected downstream alluvial sand deposits which are used as campsites by recreational boaters. Inventories of campsite numbers and sizes conducted in 1973, 1983 and 1991, and comparison of aerial photograph series taken in 1965, 1973, 1984 and 1990 show that there has been a system‐wide decrease in the number and size of campsites. Campsites are unevenly distributed along the river, and availability is regarded as ‘critical’ along reaches comprising 45% of the river, based on interviews with river guides. During the first 10 years of Glen Canyon Dam operations, at least 30% of all campsites decreased in size. During the next 18 years, between 1973 and 1991, 32% of all campsites decreased in size, and campsite capacity decreased by 44%. High annual dam releases in excess of power plant capacity in 1983 caused a net system‐wide increase in the number of campsites, but decreased campsite capacity in two critical reaches. The ‘benefit’ of sand aggradation due to the 1983 high flow was short‐lived, and by 1991 only a few campsites were larger than they had been in 1973. In contrast, other sites, especially in critical reaches, were eroded by the 1983 high flows and have not recovered in size. Options for future dam management must consider the variable response of campsites to high flows in critical and non‐critical reaches and the duration over which ‘beneficial’ high flow effects persist.
Characterization of river channel adjustments in the thames basin, south‐east England
Authors: Downs Peter W.
Published: February 2007

The increasing involvement of fluvial geomorphology in river channel management has highlighted the desirability of being able to predict spatially differentiated river channel adjustment in relation to prevailing drainage basin characteristics. An exploratory analysis, using data derived from geomorphological reconnaissance surveys and maps, was carried out with the aim of characterizing river channel adjustments in four catchments within the Thames basin. As many of the variables are categorical in nature, logistic regression is utilized to generate multivariate equations which relate four styles of adjustment to catchment characteristics describing rock type, gradient, land use and channel management. Using only the variables which are statistically significant provides a goodness of fit of around 50%. Geomorphological interpretations of the characterizations are provided and, in general, indicate the varying balance between areally extensive natural controls and more localized human influences in shaping the individual styles of adjustment. In the studied lowland environment it appears that few channels are capable of recovering their sinuosity after channel management, thus highlighting the importance of conserving currently sinuous channels and the restoration of previously straightened reaches. Low gradient rural channels set on Chalk or clay favour deposition and thus may be targeted for maintenance operations. Erosive enlargement of the cross‐section is promoted where channel straightening takes place in zones of high gradient; an option which should be minimized to reduce further management expenditure.
Channel planform change on the river dee meanders, 1876–1992
Authors: Gurnell A. M. , Downward S. R. , Jones R.
Published: February 2007

Channel planform change was investigated along an 18 km section of the River Dee on the Welsh‐English border by overlaying information from historical maps and air photographs. The information on river planform change spans the last 115 years, during which time the river has been subject to increasing flow regulation, which may have affected its planform. The downstream location of the reach provides two additional factors which may have an impact on the nature and rate of planform change through their influence on energy conditions in the reach: a tidal backwater influence on the downstream section of the reach; and a low angle of slope.

The reach has shown very small changes in planform over the last 115 years, which have been successfully identified by a geographical information system (GIS)‐based data handling methodology, which not only allows the estimation of a variety of indices of change, but also supports the estimation of the potential errors associated with registering the historical sources to a common base and digitizing the channel boundary locations. The study is successful in identifying channel planform change because it has utilized a GIS‐based as opposed to a manual approach, but it represents the lower limit to which bank movement can be confidently identified in a low‐power river environment from 1:10000 scale sources.

The changes identified by the GIS‐based methodology include a decrease in channel mobility in a downstream direction; a predominantly oscillatory movement pattern in locations where channel movement has occurred; and an apparent propagation of a decrease in channel width downstream through the reach during the period since 1949, which is the main period of increasing flow regulation.
Magnitude‐frequency analysis of sediment transport in the lower Mississippi river
Authors: Biedenharn David S. , Thorne Colin R.
Published: February 2007

Magnitude‐frequency analysis of gauging station records (1950‐1982) on the Lower Mississippi shows that there is a clearly defined dominant flow of about 30000 m3 /s. This lies within an effective range of channel‐forming flows between 17000 and 40000 m3 /s, which are responsible for transporting a disproportionately large percentage of the sediment load. The 33 year period of record is sufficiently long that the occurrence of an extreme high flow event does not significantly change these results. Hydrographic survey data, long‐profile records and stage‐discharge relationships from calibrated one‐dimensional flow models indicate that the dominant discharge corresponds to ‘bar‐full’ discharge on the Lower Mississippi and that the effective range of flows occurs between the stage that just tops mid‐channel bars and that which significantly overtops the banks. Historical trends in bar growth suggest that bar‐top elevations have generally risen to the dominant flow elevation over the last 30 years. In this trained river, where most of the banks are protected by revetments and the alignment is fixed by groynes and spurs, the mid‐channel bars represent the major, contemporary morphological feature of the alluvial river.
Macrozoobenthos abundance and community composition in three lower Rhine floodplain lakes with varying inundation regimes
Authors: Van Brink F. W. B. Den , Beljaards M. J. , Boots N. C. A. , Van Velde G. Der
Published: February 2007

The relative importance of lake inundation regime, littoral substrate and season for macrozoobenthos abundance and community composition was studied in three Lower Rhine floodplain lakes situated along a flood duration gradient. In each lake the macrozoobenthos density, biomass and community composition were determined monthly over one year in two contrasting littoral substrates (sandy‐mineral sediments and clayey‐organic sediments). The influence of the lake inundation regime on the macrozoobenthos abundance was tested against those of littoral substrate and season with a three‐way analysis of variance (ANOVA). Between‐lake variation in macrozoobenthos abundance was clear for Bivalvia, Ephemeroptera, Heteroptera and Trichoptera. Bivalvia (Pisidium sp.) were most abundant in the frequently flooded lake, Heteroptera [Micronecta sp., Sigarafalleni (Fieber), S. striata (L.)] in the rarely flooded lake and Trichoptera [Mystacides longicornis (L.), M. nigra (L.)] and Ephemeroptera [Caenis horaria (L.), C. luctuosa Burmeister] in the isolated, non‐flooded lake, suggesting an impact of inundation regime on the abundance of these dominant taxa in Lower Rhine floodplain lakes. In each lake the annual average abundance of macrozoobenthos was dominated by Gastropoda [Bithynia tentaculata (L.), Potamopyrgus antipodarum (Gray), Valvata piscinalis (Müller)].

Between‐lake variations in the relative densities of macrozoobenthos functional feeding groups suggests an impact of the inundation regime on the macrozoobenthos communities via the availability of nutritional resources. Relative densities of filter‐feeders (e.g. Pisidium sp.) were highest in the frequently flooded lake with its high phytoplankton biomass and poorly developed vegetation. Shredders (e.g. Mystacides sp.) were most numerous in the non‐flooded lake with its well developed aquatic vegetation and low phytoplankton biomass.

Within‐lake variations in macrozoobenthos abundance could be attributed to littorai substrate and season. The importance of substrate on macrozoobenthos abundance was most clear for Oligochaeta and Trichoptera. The importance of season on macrozoobenthos abundance was clear for the total macrozoobenthos and for all taxonomic groups, except Oligochaeta. Correlations between the total macrozoobenthos abundance and seasonally fluctuating parameters, i.e. flood pulse duration, water level, water temperature and vegetational coverage in the lakes, suggest that hydrological parameters were most important in the frequently flooded lake, whereas vegetational coverage and water temperature were most important in the isolated, non‐flooded lake.
Low flows and recovery of macroinvertebrates in a small regulated chalk stream
Authors: Wood P. J. , Petts G. E.
Published: February 2007

The ecological effects of, and subsequent recovery from, a protracted drought exacerbated by groundwater abstractions on a small English chalk stream are described. Preliminary data from 15 sites showed significant physical and biotic changes between two surveys (in 1992 and 1993) and between ‘upland’ and ‘lowland’ sectors. At the end of the drought (1992) the macroinvertebrate community was severely reduced in the upland sector—with low abundances and species richness—but recovery was dramatic with the return of normal flows. In contrast, relatively little change was observed in the lowland sector. The observed faunal differences are discussed in relation to information on the impact of previous droughts and recovery rates.
NiFe Nanoparticles: A Soft Magnetic Material?
Authors: Margeat Olivier , Ciuculescu Diana , Lecante Pierre , Respaud Marc , Amiens Catherine , Chaudret Bruno
Published: February 2007

Polytetrahedral NiFe nanoparticles with diameters of (2.8±0.3) nm have been obtained by hydrogenation of Ni[(COD)2] (COD=1,5‐cyclooctadiene) and Fe[{N(SiMe3)2}2] at 150 °C using stearic acid and hexadecylamine as stabilizing ligands. The nanoparticles are superparamagnetic at room temperature and display a blocking temperature of 17.6 K. Their anisotropy (2.7×105J m−3) is determined to be more than two orders of magnitude higher than that of the bulk NiFe alloy (103J m−3) and is close to that determined for Fe nanoparticles of the same size. Still, they display a magnetization of (1.69±0.05) μB per metallic atom, identical to that of the bulk NiFe alloy. Combining the results from X‐ray absorption and Mössbauer studies, we evidence a progressive enrichment in iron atoms from the core to the surface of the nanoparticles. These results are discussed in relation to both size and chemical effects. They show the main role played by the enriched Fe surface on the magnetic properties and address the feasibility of soft magnetic materials at the nanoscale.
Effect of Osmotic Pressure on Starch: New Method of Physical Modification of Starch
Authors: Pukkahuta Chirdchan , Shobsngob Sujin , Varavinit Saiyavit
Published: February 2007

A new method of physical modification of starch in the presence of high concentrated salt solution is presented, called “Osmotic Pressure Treatment” (OPT). OPT was introduced in order to produce the same physically modified products as obtained by conventional heat‐moisture treatment (HMT) of starch. Potato starch was selected for the comparative study of the two methods. For the OPT method, potato starch was suspended in a saturated solution of sodium sulfate and heated in an autoclave at 105°C and 120°C ,which corresponded to the calculated osmotic pressures of 328 and 341 atm (332 and 345 bar, respectively) (assuming sodium sulfate dissociates completely) for 15, 30 and 60 min, respectively. For the HMT method, starch with 20% moisture content was placed in a Duran bottle, then the same heat treatment method in the autoclave was applied. Light and scanning electron microscopy (SEM) showed that OPT of starch changed the shape of the starch granules to a folded structure, while the starches remained unchanged after HMT. The RVA viscogram for the OPT starch exhibited a decrease in the peak viscosity without a breakdown and an increase of the pasting temperature when increasing the temperature and time, which was in an agreement with the viscosity patterns for the HMT starches. X‐ray diffraction patterns were altered from B to A+B for the HMT and from B to A type for the OPT starch when treated at 120°C. After OPT, the gelatinization temperatures (To, Tp, and Tc) of the starch increased significantly with increasing temperature and time, whereas only the Tc of starch increases after HMT. The biphasic broadening of the peaks (high Tc‐To) can be explained by an inhomogeneous heat transfer during HMT. Narrow peaks in the DSC curve can be an indication for a better homogeneity of the OPT samples. However, both methods provide a similar decrease in the gelatinization enthalpy (ΔH). The amylose‐amylopectin ratio calculated from the HPSEC patterns was strongly increased for HMT starches at 105°C for 60 min and 120°C for 30 min and decreased after treatment at 120°C for 60 min. For OPT starches the ratio was strongly increased at 120°C for 15 min and decreased after prolong heating. The OPT provides a uniform heat distribution in the starch suspension. This allows the modified starch to be produced on a larger scale.
Synthesis and Optimization of the Reaction Conditions of Starch Sulfates in Aqueous Solution
Authors: Cui Dapeng , Liu Mingzhu , Liang Rui , Bi Yinghui
Published: February 2007

Starch sulfate was prepared by chemical modification of potato starch with trisulfonated sodium amine (N(SO3Na)3), which was synthesized by reaction of sodium bisulfite and sodium nitrite in aqueous solution. The factors that could affect the degree of substitution (DS) of potato starch were investigated in detail, which included reaction temperature and time of preparing the sulfating agent, reaction temperature and time of synthesizing the starch sulfate, dosage of sulfating agent and potato starch, pH of sulfation reaction medium, and the ratio of liquid volume to starch mass. A starch sulfate with DS of 2.14 was obtained under optimal conditions. FTIR spectra showed the characteristic absorptions of sulfate ester bonds at 1236 cm−1 and 821 cm−1.
One‐Step Extraction and Concentration of Polyunsaturated Fatty Acids from Fish Liver
Authors: Guil‐Guerrero J. L. , López‐Martínez J. C. , Rincón‐Cervera M. A. , Campra‐Madrid P.
Published: February 2007

The fatty acids (FA) eicosapentaenoic acid (20:5ω‐3; EPA) and docosahexaenoic acid (22:6ω‐3; DHA), which have several health benefits, have been concentrated from mako shark liver (Isurus oxyrinchus). The process was carried out in one single step, in which fish liver oil was simultaneously extracted, saponified and concentrated. Additionally, the polyunsaturated fatty acids (PUFA) concentrate was winterized to crystallize the remaining saturated FA, resulting in a further increase in the concentration of DHA and EPA. Two variables, temperature and water concentration in the saponification mixture, were optimized to increase the concentration of ω‐3 PUFA. Best results were obtained at 12 °C and 0% water content in the mixture, obtaining 17.8% purity and 77.6% yield of EPA; DHA purity and yield were 33.3 and 82.2%, respectively.
Cytochromes P460 and c′‐beta; A new family of high‐spin cytochromes c
Authors: Elmore Bradley O. , Bergmann David J. , Klotz Martin G. , Hooper Alan B.
Published: February 2007

Cytochromes‐P460 of Nitrosomonas europaea and Methylococcus capsulatus (Bath), and the cytochrome c′ of M. capsulatus, believed to be involved in binding or transformation of N‐oxides, are shown to represent an evolutionarily related new family of monoheme, ∼17 kDa, cytochromes c found in the genomes of diverse Proteobacteria. All members of this family have a predicted secondary structure predominantly of beta‐sheets in contrast to the predominantly alpha‐helical cytochromes c′ found in photoheterotrophic and denitrifying Proteobacteria.
Adaptive value of participatory biodiversity monitoring in community forestry
Authors: LAWRENCE ANNA , PAUDEL KRISHNA , BARNES RICHARD , MALLA YAM
Published: February 2007

In the context of action research in community forests, stakeholders' values for biodiversity can be elicited, communicated and understood with the help of a multidimensional conceptual framework. This incorporates levels of diversity (genes, species, habitats and processes), types of values (direct use, indirect use, option and existence) and stakeholders. This paper explores the effect of using this framework on forest monitoring, learning and communication, and wider implications for conservation, in Baglung District (Nepal). Monitoring was initially an unfamiliar concept to villagers, but the process clarified its purpose, whilst helping to elicit and exchange values and knowledge amongst stakeholders. This precipitated proposals for silvicultural experimentation and social inquiry into the diversity of users' needs. The framework allowed the translation of local value statements into categories recognized by other actors. It aided external stakeholders in understanding the factors contributing to values held by community forest users. Villagers' appreciation of ‘quality’ forest did not necessarily equate to the most ‘biodiverse’ forest, but rather the greenest and densest and that stocked with useful species. Elite domination, tenure and access to markets affected values assigned and behaviour in forest management. Elicitation of these values provoked questioning of forest management decisions and benefit sharing among community forest users. This, in turn, stimulated more democratic forest management and more inclusive, wide-ranging biodiversity values. Participatory monitoring is more conceptually challenging than is usually recognized, and the links between equity and conservation merit further attention in different cultural contexts.
Response of peatland carbon dioxide and methane fluxes to a water table drawdown experiment
Authors: Strack M. , Waddington J. M.
Published: February 2007

Northern peatlands play an important role in the global carbon cycle representing a significant stock of soil carbon and a substantial natural source of atmospheric methane (CH4). Peatland carbon cycling is affected by water table position which is predicted to be lowered by climate change. Therefore we compared carbon fluxes along a natural peatland microtopographic gradient (control) to an adjacent microtopographic gradient with an experimentally lowered water table (experimental) during three growing seasons to assess the impact of water table drawdown on peatland‐atmosphere carbon exchange. Water table drawdown induced peat subsidence and a change in the vegetation community at the experimental site. This limited differences in carbon dioxide (CO2) exchange between the control and experimental sites resulting in no significant differences between sites after three seasons. However, there was a trend to higher respiration rates and increased productivity in low‐lying zones (hollows) and this was coincident with increased vegetation cover at these plots. In general, CH4 efflux was reduced at the experimental site, although CH4 efflux from control and experimental hollows remained similar throughout the study. The differential response of carbon cycling to the water table drawdown along the microtopographic gradient resulted in local topographic high zones (hummocks) experiencing a relative increase in global warming potential (GWP) of 152%, while a 70% reduction in GWP was observed at hollows. Thus the distribution and composition of microtopographic elements, or microforms, within a peatland is important for determining how peatland carbon cycling will respond to climate change.
Tropical tropopause climatology as observed with radio occultation measurements from CHAMP compared to ECMWF and NCEP analyses
Authors: Borsche M. , Kirchengast G. , Foelsche U.
Published: February 2007

A temperature climatology from radio occultation measurements of the CHAllenging Minisatellite Payload (CHAMP) satellite, comprising five years of measurements from September 2001 to August 2006, was analyzed in the tropical (15°S–15°N) tropopause region. Validation against operational analyses of the European Centre for Medium‐Range Weather Forecasts (ECMWF) showed excellent overall agreement except near the tropical tropopause, where systematic differences generally amount to −1 K to −2 K. Validation against tropopause temperatures from the U.S. National Centers for Environmental Prediction (NCEP) reanalyses showed NCEP deviations of about +2 K to +4 K. The ECMWF deviations can be attributed to the lower vertical resolution and weaker representation of atmospheric wave activity in ECMWF analyses. This evidence is confirmed by improved data from February 2006 onwards, where an enhancement of the ECMWF analyses became effective. Initial inspection of extreme tropical tropopause profiles provided evidence that extremely cold tropopause temperatures can reach −100°C.
Irrigation cooling effect: Regional climate forcing by land‐use change
Authors: Kueppers Lara M. , Snyder Mark A. , Sloan Lisa C.
Published: February 2007

Regional detection of a greenhouse warming signal relies on extensive, long‐term measurements of temperature. The potentially confounding impact of land‐cover and land‐use change on trends in temperature records has mostly focused on the influence of urban heat islands. Here we use a regional climate model to show that a regional irrigation cooling effect (ICE) exists, opposite in sign to urban heat island effects. The magnitude of the ICE has strong seasonal variability, causing large dry‐season decreases in monthly mean and maximum temperatures, but little change in rainy‐season temperatures. Our model produced a negligible effect on monthly minimum temperature. In California, the modeled regional ICE is of similar magnitude, but opposite sign, to predictions for future regional warming from greenhouse gases. Given our results for California and the global importance of irrigated agriculture, past expansion of irrigated land has likely affected observations of surface temperature, potentially masking the full warming signal caused by greenhouse gas increases.
Spatial and temporal variability of diurnal wind forcing in the coastal ocean
Authors: Hunter Eli , Chant Robert , Bowers Louis , Glenn Scott , Kohut Josh
Published: February 2007

Spatial and temporal variability of diurnal wind forcing and the coastal response is characterized for the New York Bight from February through May, 2005. This analysis demonstrates that diurnal wind forced motions are significant in the coastal ocean during the spring and summer months, near shore and as far as 100 km offshore. A doubling of diurnal current amplitudes is common in the spring compared to the winter months, associated with an increase in sea/land breeze days. Diurnal fluid motions due to sea/land breeze events can account for up 50% of the total kinetic energy during the spring.
Estimation of aerosol optical properties and radiative effects in the Ganga basin, northern India, during the wintertime
Authors: Dey Sagnik , Tripathi S. N.
Published: February 2007

An aerosol model has been developed using mass size distributions of various chemical components measured at Kanpur (an urban location in the Ganga basin, GB, in northern India) and applied to estimate the radiative effects of the aerosols over the entire GB during the winter season. The number size distribution of various species was derived from the measured mass concentration, and the optical properties were calculated using Mie theory. The maximum anthropogenic contribution to the total extinction was estimated to be ∼83%. The relative contributions of various species to the aerosol optical depth (AOD) at 0.5 μm are in the following order: (NH4)2SO4 (nss‐SO4, 30%), nitrate (NO3−, 24%), salt (mainly NaCl and KCl, 18%), dust (17%) and black carbon (BC, 11%). Relative contribution of nss‐SO4, NO3− and salt to the calculated AOD decreases with wavelength, and that of dust increases with wavelength, whereas BC contribution is spectrally insensitive. The extinction coefficient strongly depends on the RH, as the scattering by fine mode fraction, which contributes 88% to the total extinction, is enhanced at high ambient RH. The spectral variation of absorption coefficient indicates that the most likely source of BC in this region is fossil fuel. The spectral variation of single scattering albedo (SSA) in the coarse mode fraction suggests mixing of BC and dust particles. During the observational period, the mean shortwave (SW) clear sky top of the atmosphere (TOA) and surface forcing over Kanpur are estimated to be −13 ± 3 and −43 ± 8 W m−2, respectively. The corresponding longwave forcings are 3.6 ± 0.7 and 2.9 ± 0.6 W m−2, respectively. Mean AOD at 0.55 μm over the GB as derived from MODIS data is 0.36 ± 0.14. Extending our model over the entire GB, the net mean TOA and surface forcing become −6.4 and −30.2 W m−2 (with overall ∼15% uncertainty). This results in high atmospheric absorption (+23.8 W m−2), translating into a heating rate of 0.67 K day−1. The SW surface to TOA forcing ratio (∼3.7) over the GB is 23% higher than the corresponding value for Indian Ocean. The aerosols reduce the incoming solar radiation reaching the surface by ∼19%, which has significant effect on the regional climate.
Dust transport over the eastern Mediterranean derived from Total Ozone Mapping Spectrometer, Aerosol Robotic Network, and surface measurements
Authors: Kalivitis N. , Gerasopoulos E. , Vrekoussis M. , Kouvarakis G. , Kubilay N. , Hatzianastassiou N. , Vardavas I. , Mihalopoulos N.
Published: February 2007

Multiyear surface PM10 measurements performed on Crete Island, Greece, have been used in conjunction with satellite (Total Ozone Mapping Spectrometer (TOMS)) and ground‐based remote sensing measurements (Aerosol Robotic Network (AERONET)) to enhance our understanding of the evolution of mineral dust events over the eastern Mediterranean. An analysis of southerly air masses at altitudes of 1000 and 3000 m over a 5 year period (2000–2005), showed that dust can potentially arrive over Crete, either simultaneously in the lower free troposphere and inside the boundary layer (vertical extended transport (VET)) or initially into the free troposphere with the heavier particles gradually being scavenged inside the boundary layer (free troposphere transport (FTT)). Both pathways present significant seasonal variations but on an annual basis contribute almost equally to the dust transport in the area. During VET the aerosol index (AI) derived from TOMS was significantly correlated with surface PM10, and in general AI was found to be adequate for the characterization of dust loadings over the eastern Mediterranean on a climatological basis. A significant covariance between PM10 and AOT was observed during VET as well, indicating that AOT levels from AERONET may be estimated by PM10 levels at the surface. Surface measurements are thus crucial for the validation of remote sensing measurements and hence are a powerful tool for the investigation of the impact of aerosols on climate.
Scintillation modeling using in situ data
Authors: Wernik A. W. , Alfonsi L. , Materassi M.
Published: February 2007

Satellite in situ measurements of plasma (electron) density fluctuations provide direct information about the structure and morphology of irregularities that are responsible for scintillation of radio waves on transionospheric links. When supplemented with the ionosphere model and irregularity anisotropy model, they can be applied to model morphology of scintillation provided a suitable propagation model is used. In this paper we present a scintillation climatological model for the Northern Hemisphere high‐latitude ionosphere, which makes use of the Dynamics Explorer 2 retarding potential analyzer plasma density data, IRI ionosphere model, and the phase screen propagation model. An important aspect of our work is that we derived from the satellite data not just the turbulence strength parameter Cs but also the spectral index p, which influences the scintillation level as well. We discuss the magnetic activity, season, magnetic time, and latitude dependence of these parameters. We were able to reproduce successfully the observed scintillation intensity diurnal and seasonal variations. The model satisfactorily describes the expansion of the scintillation zone under magnetically disturbed conditions and reproduces the dawn‐dusk asymmetry in the scintillation intensity. The results demonstrate the usefulness of the proposed approach.