effects of hydraulic roughness on surface textures of gravel bed rivers field studies of forest gravel bed rivers in northwestern washington and southeastern alaska demonstrate that bed surface grain size is responsive to hydraulic roughness caused by bank irregularities bars and wood debris we evaluate textural response by comparing reach average median grain size d50 to that predicted from the total bank full boundary shear stress t0 bf representing a hypothetical reference condition of low hydraulic roughness for a given t0 bf channels with progressively greater hydraulic roughness have systematically finer bed surfaces presumably due to reduced bed shear stress resulting in lower channel competence and diminished bed load transport capacity both of which promote textural fining in channels with significant hydraulic roughness observed values of d50 can be up to 90 smaller than those predicted from t 0 bf we find that wood debris plays an important role at our study sites not only providing hydraulic roughness but also influencing pool spacing frequency of textural patches and the amplitude and wavelength of bank and bar topography and their consequent roughness our observations also have biological implications we find that textural fining due to hydraulic roughness can create usable salmonid spawning gravels in channels that otherwise would be too coarse

application of an inverse method to interpret 231pa 230th observations from marine sediments constraints then sediment 231 pa 230 th data for each time interval are combined with an advection scavenging model in order to determine their in consistency with the modern circulation estimate we find that the majority of sediment 231 pa 230 th data for the holocene lgm or h1 can be brought into consistency with the modern circulation if plausible assumptions are made about the large scale distribution of 231 pa and about model uncertainties moreover the adjustments in the data needed to reach compatibility with a hypothetical state of no flow no advection are positively biased for each time interval suggesting that the 231 pa 230 th data including that for h1 are more consistent with a persistence of some circulation than with no circulation our study does not imply that earlier claims of a circulation change during the lgm or h1 are inaccurate but that these claims cannot be given a rigorous basis given the current uncertainties involved in the analysis of the 231 pa 230 th data

water column 230th systematics in the eastern equatorial pacific ocean and implications for sediment focusing 230 th and 232 th abstract in an effort to investigate the cause of higher than expected sediment inventories of 230 th in the panama basin thorium isotopes were measured in eight deep water casts within the guatemala panama and peru basins along a meridional transect at 861w between 6 51n and 8 51s dissolved 230 th concentrations increase linearly from the surface to 1000 m at each transect station below 1000 m the deep waters of the panama basin show the highest deficit 50 of 230 th assuming a reversible exchange of 230 th between dissolved and sinking particulate matter and in comparison with the globally averaged water column 230 th peru basin waters have a larger range of dissolved 230 th concentrations 7 9 16 5 fg kg than that within panama basin waters 5 7 7 1 fg kg there is a progressive decrease in average dissolved deep water 41000 m 230 th concentrations from the southernmost sites in the peru basin toward the panama basin we suggest that intense scavenging by upwelling derived productivity near the equator 7 21 and resuspension of ubiquitous mn rich particulates in panama basin sediments are the primary causes of the significant south to north lateral gradient in deep water dissolved 230 th although 230 th from peru basin waters may be transported and then scavenged and ultimately buried in the panama basin our calculations suggest that the quantity of advected 230 th is relatively small between 15 and 30 of the total 230 th being produced within water column of the panama basin itself panama basin sediment focusing factors greater than 1 3 cannot be explained by lateral export and excess scavenging of water column 230 th dissolved 232 th concentra tions in addition to being the lowest reported so far in the literature fall within a very narrow range 6 26 pg kg and are generally invariable with depth this invariability suggests the dissolution of dust in surface waters as a likely sole source of dissolved 232 th for the entire water column

factors controlling geochemical and mineralogical compositions of coals preserved within marine carbonate successions a case study from the heshan coalfield southern china abstract the late permian coals in the heshan coalfield of southern china are preserved within marine carbonate successions and characterized by super high organic sulfur 5 13 10 82 minerals identified in the coals include quartz kaolinite illite mixed layer illite smectite albite pyrite marcasite calcite and dolomite along with trace amounts of smectite fluorite strontianite rey bearing carbonate minerals jarosite and water bearing fe oxysulfate the coals are very rich in trace elements including f up to 3362 g g v up to 270 g g se up to 24 4 g g mo up to 142 g g u up to 111 g g and to a lesser extent sr y zr nb cd cs heavy rare earth elements hf ta w hg and th previous studies attributed the high organic sulfur and elevated trace elements to the seawater influence or the formation of soil horizons before the accumulation of peat in the basin however mineralogical and geochemical data presented in this study have shown that the sediment source region and multi stage hydrothermal fluids are the dominant influences on the mineralogical composition and elevated trace elements in the coal although seawater influence also contributed to the composition of the mineral matter for example a large proportion of the quartz and clay minerals as well as almost all the albite in both the coal benches and the parting mudstones were derived from detrital materials of terrigenous origin in the yunkai upland high concentrations of lithophile trace elements were also derived from the sediment source region minerals including fluorite calcite dolomite strontianite and rey bearing carbonate minerals were derived from multi stage hydrothermal activities high concentrations of v mo and u that occur through the coal seam sections were probably derived from hydrothermal solutions during peat accumulation or at the early diagenetic stages the hydrothermal fluids also corroded the syngenetically formed minerals quartz albite and pyrite and caused re distribution of lithophile elements from partings to the underlying coal benches resulting in higher key element ratios yb la nb ta and zr hf and more abundant heavy rare earth elements in the coal benches than in the immediately overlying partings

disrupted coal and carbonate facies within two pennsylvanian cyclothems southern illinois basin united states two cyclothems contain an unusual suite of disrupted fabrics this study9s interdisciplinary integration of coal maceral and sedimentological information offers significant new interpretations of coal limestone interchange both depositionally and diagenetically disrupted fabrics within the herrin coal and providence limestone are interpreted as representing previously undocumented interactive processes between coals and limestones the herrin coal contains brecciated beds that are the result of marine transgression over a coastal plain mire representing high energy conditions at the swamp beach interface this interface has rarely been documented in detail peat is inherently unstable prior to its conversion to coal and we document this by interpreting conglomeratic beds in overlying strata differential compaction of herrin peats generated subaqueous debris flows in the overlying providence limestone this mechanism for syndiagenetic and early diagenetic sediment deformation has not been previously recognized in addition near surface and surface processes produced other disrupted fabrics in the providence limestone such as in situ mosaic breccias nodular fabrics and calcrete horizons this study also documents that stratigraphically adjacent alkaline carbonate sediments were further altered by undersaturated acidic pore waters derived from compacting peats during early diagenesis our interdisciplinary approach to distinguishing and interpreting all of these disrupted fabrics led to a new appraisal of the importance of depositional and postdepositional interactions between coal and limestone the presence of mire deposits can have a significant influence on the thickness distribution and fabrics in overlying strata in cyclothems climatic and eustatic changes may control overall depositional patterns but peat compaction may determine certain facies

dam induced base level rise effects on the gravel bed channel planform little is known on the planform evolution of gravel bed rivers in base level raised backwater zones upstream from dam reservoirs the general model of river channel response to base level rise predicts a decrease in river sinuosity however the observations of channel adjustments in the reservoir backwater document a narrower and more sinuous channel developed as a result of fine sediment deposition and vegetation expansion here the long term aerial photo based observations 1963 2015 of two gravel bed rivers of different initial channel pattern the dunajec and its tributary the smolnik located in the base level raised zone of the roznow reservoir in the polish carpathians were analyzed the results show that the initially multi thread river in backwater was significantly narrowed and its sinuosity increased phase 1 which was followed by the stabilization of channel planform phase 2 however in the initially single thread river only phase 2 occurred the rate of channel narrowing observed on the initially multi thread river was positively related to the initial channel width r2 0 90 p 0 0001 and bar width r2 0 81 p 0 0001 the increase in sinuosity was higher in the previously wider channel section and did not occur in the valley confined zones of the single thread river the results are conceptualized in a two phase conceptual model which hypothesizes that the trajectories of the long term planform adjustments of gravel bed river in backwater are controlled by the initial river morphology which creates accommodation space for fine sediment deposition and associated vegetation expansion

230th and 232th distributions in mid latitudes of the north pacific ocean effect of bottom scavenging abstract vertical distributions of total 230 th and dissolved 232 th were determined in the mid latitudes of the north pacific ocean 8 n 95 w 40 n 160 e the observed 232 th concentrations are some of the lowest values reported for oceans because of low biogenic particle flux high 230 th activity is exhibited in the central gyre most vertical distributions of 230 th in the pacific ocean have been described well using the reversible scavenging model however we observed the depletion of total 230 th compared with a reversible scavenging model prediction for the deep layers in the mid latitudes of the north pacific ocean considering the time scale of the scavenging residence time of th horizontal eddy diffusion from the higher particle flux region could not have a major influence on 230 th depletion in deep waters the observed depletion is partly explained by lateral advection adopting the scavenging mixing model additionally a bottom scavenging process above the seafloor and a diffusion process are considered to explain the 230 th deficit taking into account the time scale of the scavenging residence time of th in deep waters 230 th in deep water to the upper layers

multi thread rivers in the polish carpathians occurrence decline and possibilities of restoration multi thread rivers are typified by the presence of interconnected channels separated by mid channel bars or the islands forming as a result of vegetation encroachment on mid channel bars high gradients of channels and valley floors high discharge variability relatively low content of fine cohesive sediments in the alluvial plain coarse bed material and high sediment supply are environmental conditions that favour the development of braided channel pattern under natural conditions of the holocene island braided channel pattern was typical of the rivers in the foreland of the tatra mountains and most likely also those draining the parts of the flysch outer carpathians underlain by thick bedded sandstones complexes these braided channels formed in the rivers flowing through mostly non cohesive floodplains and fed with coarse grained material exceeding competence of the rivers progressive deforestation of mountain catchments with the increasing area of cultivated hillslopes resulted in higher flood peaks and substantially increased sediment supply to river channels coupled with greater humidity of the final stages of the little ice age this led to the transformation of the island braided rivers into bar braided ones throughout the nineteenth century the braided channel morphology expanded downstream to the foreland river reaches in turn over the twentieth century the braided morphology nearly disappeared from polish carpathian rivers mostly as a result of their channelization the effectiveness of these works was however strengthened by a decrease in sediment supply to the rivers caused by land use changes and by the reduced availability of bed material for fluvial transport resulting from in channel gravel mining and partitioning of rivers with dam reservoirs environmental changes which have since occurred in the river catchments and disruption of the continuity of sediment transport by dams limit the feasibility of the restoration of braided channel pattern in polish carpathian rivers to their reaches supporting such morphology under natural conditions of the holocene

ragged edge of the herrin no 11 coal western kentucky abstract the herrin no 11 coal in western kentucky is normally a bright banded high vitrinite high sulfur coal three sites have been found where the coal deviates from the expected appearance in union county a site known only from a literature description the upper two thirds of the coal was described as a cannel in ohio county a thin truncated section of the herrin coal has a greater abundance of liptinite and inertinite rich microlithotypes towards the top of the seam the various microlithotypes were frequently found in brecciated assemblages in hopkins county the herrin coal was found to be largely a coarse breccia of oxidized macerals cemented by calcite a marine limestone was present as a parting within the coal each occurrence represents the edge of the coal the sites varied in the energy of the environment and perhaps also in proximity to marine waters

similar rates of modern and last glacial ocean thermohaline circulation inferred from radiochemical data today the ocean thermohaline circulation transports half of the 231pa produced by radioactive decay in the atlantic ocean water column to the southern ocean this export respectively imparts low and high 231pa 230th ratios to the surface sediments of these oceans ocean sediments from the last glacial maximum bear a similar isotopic fingerprint implying that advection of north atlantic deep intermediate water into the circumpolar deep water of the southern ocean occurred at a similar or slightly higher rate during the last glacial period

how natural are alpine mountain rivers evidence from the italian alps historical human induced channel adjustments in lowland gravel bed rivers have been documented in several geographical contexts worldwide in particular it is now widely accepted that the vast majority of european rivers are far from any natural reference state prior to anthropic disturbances and a complete restoration is hardly achievable however few investigations have addressed changes that have occurred in mountain rivers of the alps and these channels are commonly reckoned quite natural by society this paper intends to describe how human pressure on italian alpine basins has been quite relevant for several centuries in terms of land use variations in channel structures timber transport splash damming and riparian vegetation management such that nowadays reference conditions cannot be found even in small mountain creeks in addition recent natural climatic variations e g the little ice age are superimposed on human disturbances thus defying the definition of any equilibrium morphological conditions even under human free states a summary of published as well as unpublished works on historical channel adjustments in rivers of the italian alps is presented in order to document the impacts deriving from human pressure at different basin scales and for different river morphologies from steep confined streams to large unconfined rivers general options for river management and restoration actions aiming to combine geomorphological functionality and flood hazard mitigation are discussed in the light of the current european legislative context copyright 2011 john wiley sons ltd

230th in the eastern north atlantic the importance of water mass ventilation in the balance of230th the230th distribution in the water column on a north south transect in the eastern north atlantic was measured using thermal ionization mass spectrometry tims water samples at three locations l1 33 n 21 6 w l2 47 4 n 19 5w and l3 54 4 n 21 1 w were filtered and the dissolved and particulate fractions were analysed for their230th and232th contents in the upper water column 2000 m at l2 suggested by our model 8 25 years is probably too rapid in comparison with previous findings based on chlorofluorocarbon data enhanced scavenging of230th would be an alternative explanation for the low concentration in neadw at l2 with the scavenging mixing model we calculated an advective export flux of230th of up to 50 of the production in the water column in the eastern north atlantic advective loss of230th has to be taken into account when using the230th flux into sediments for paleoceanographic studies in ocean basins where deep water residence time is comparable to the230th scavenging residence time

geochemical petrographic and palynologic characteristics of two late middle pennsylvanian asturian coal to shale sequences in the eastern interior basin usa abstract two coal to shale sequences of late middle pennsylvanian asturian age from the southern portion of the eastern interior illinois basin usa were examined geochemically petrographically and palynologically the springfield coal was found to be moderately low in ash yield and high in total sulfur content petrographically the coal is high in vitrinite content and low in liptinite and inertinite palynologically the bed is co dominated by spores of arborescent lycopod and tree fern affinities the examination of closely spaced bench samples revealed vertical species variation within both of these plant groups lycospora micropapillata l orbicula both of which were produced by paralycopodites are most abundant in basal coal benches whereas lycospora granulata produced by lepidophloios is the dominant arborescent lycopod spore throughout the rest of the bed thymospora pseudothiessenii is the dominant tree fern spore throughout most of the coal with laevigatosporites globosus becoming dominant in the top most coal benches the herrin coal bed is also moderately low in ash yield and high in total sulfur content unlike the springfield coal it contains two distinct inorganic partings that have regional extent the herrin coal also has several coal benches with increased ash and sulfur that were not present in the springfield coal bed petrographically it is dominated by vitrinite with the partings and high ash coal benches containing more inertinite and liptinite palynologically the herrin coal is dominated by arborescent lycopod spores with subdominant tree fern spores as with the springfield coal lycospora micropapillata l orbicula are the dominant arborescent lycopod spores at the base of the coal with lycospora granulata dominating the rest of the bed granasporites medius which was produced by diaphorodendron and synchysidendron occurs more frequently in the herrin coal bed and are most abundant in and in proximity to the two inorganic partings tree fern spores are less abundant in the herrin coal and do not display any discernable vertical species variation collectively both the springfield and herrin coal beds are interpreted to have formed in extensive planar topogenous mires consistently saturated peat conditions throughout the development of both paleomires are indicated by the high vitrinite contents and prevalence of arborescent lycopods the deposition of widespread inorganic partings in the herrin coal represents significant events in peat accumulation with high ash coal benches representing smaller more local events both of the coals are overlain by black very organic rich avg toc 20 marine shales the turner mine shale which directly overlies the springfield coal has layers at the coal shale contact with fairly abundant vitrinite primarily in the form of vitrodetrinite near the base of the shale but the majority of the shale is dominated by the liptinite macerals bituminite lamalginite and amorphinite micrinite is a major organic component of the shale the anna shale which directly overlies the herrin coal is similar in overall maceral composition but contains less vitrinite and more solid bitumen and micrinite trace element ratios ni co v cr v v ni indicative of paleoredox conditions indicate that both shales were deposited under mainly dysoxic to suboxic anoxic conditions the shales are interpreted to represent a progressively rising water table caused by an increase in eustatic sea levels vitrinite reflectance values in the shales are lower than corresponding values measured from the coal indicating some degree of vitrinite suppression occurring in the turner mine and anna shales

biogeography in 231pa 230th ratios and a balanced 231pa budget for the pacific ocean the ratio of unsupported protactinium 231 to thorium 230 in marine sediments pa th xs is potentially sensitive to several processes of oceanographic and climatological interest deep ocean circulation marine biological productivity as it relates to total particle flux and particle composition specifically biogenic opal and authigenic mn in order to attribute variations in pa th xs observed in sediment records to changes in specific processes through time a better understanding of the chemical cycling of these elements in the modern ocean is necessary to this end a survey was undertaken of pa th xs in surface sediments from the subarctic pacific so202 inopex expedition in combination with a pacific wide compilation of published data throughout the pacific pa th xs is robustly correlated with the opal content of sediments in the north and equatorial pacific simultaneous positive correlations with productivity indicators suggest that boundary scavenging and opal scavenging combine to enhance the removal of pa in the eastern equatorial pacific and subarctic pacific deep ocean water mass ageing 3 5 km 3 5 km associated with the pacific overturning appears to play a secondary role in determining the basin scale distribution of pa th xs a basin wide extrapolation of pa removal is performed which suggests that the pacific pa budget is nearly in balance we hypothesize that through time pa th xs distributions in the pacific could define the evolving boundaries of contrasting biogeographic provinces in the north pacific while the influence of hydrothermal scavenging of pa potentially confounds this approach in the south pacific

the stratigraphic distribution of inertinite abstract the paper presents the results of an investigation into the stratigraphic distribution of inertinite in humic coals ranging from the silurian to the neogene periods this range equals the time span during which both land plants and atmospheric oxygen evolved the survey is based on a literature study of inertinite in coals covering a variety of depositional environments and climates in all continents the inertinite percentages listed in this paper have been arranged in stratigraphic order they are the mean values based on mineral free whole coal compilations maceral compositions listed in the literature for individual subsections have been averaged to represent complete coal seams beds although this might not have been always possible due to some ambiguity in the published record moreover not all of the published and unpublished information could be used because of poor sample description obscure geographic origin or insufficient stratigraphic information the results show that there have been times in the geological past e g during the late permian in which coals were particularly rich in inertinite compared with other times e g during much of the late tertiary in which many coals contained very little inertinite occasionally such primary global trends were modulated by a diffuse distribution of inertinite percentages that correspond to differences in climate depositional settings e g active orogenic margins versus tectonically inactive shelf margins and other local or regional variations although various mechanisms for the generation of inertinite have been proposed in the past the overall pattern in its stratigraphic distribution supports the notion of incomplete combustion as the main source of inertinite in coal this points to secular variations in the atmospheric oxygen content as an explanation for the global changes in the inertinite distribution while differential subsidence and climatically influenced reaction rates governed regional and local variations in inertinite percentages

twentieth century hydromorphological degradation of polish carpathian rivers abstract case studies of the sola san and dunajec rivers are used to demonstrate changes in planform geometry of the rivers draining the western and eastern parts of the flysch polish carpathians and those originating in the high mountain tatra massif since the second half of the nineteenth century the number and width of low flow channels and the length of river reaches are compared between the nineteenth century and contemporary rivers with analysis of other features of their planform geometry prevented by differences in the cartographic presentation of rivers on austrian military maps and polish topographic maps in the second half of the nineteenth century the rivers flowed in wide channels the sola supported a braided channel along its entire course the dunajec was mostly braided with a single thread channel within gorge sections whereas for the san the braided pattern was limited to the reaches within intramontane and foreland basins over the twentieth century the braided channel pattern was nearly completely eliminated and substituted by a single thread pattern multi thread channel segments remained only in the upper course of the dunajec river average low flow channel width significantly decreased even by 66 and this was accompanied by a reduction in the variability of low flow channel width along the rivers the change in planform channel geometry was accompanied by channel incision which started earlier and has resulted in greater bed degradation in the foreland and foothill reaches of the rivers than in their mountain reaches twentieth century river changes also encompassed a radical change in the facies pattern of channel sediments accompanied by their coarsening and improved sorting and development of bed armour moreover transformation of alluvial channel beds to bedrock ones took place in many reaches of carpathian streams and rivers the degradation of physical structure of carpathian watercourses has resulted in adverse hydraulic and hydrological effects and a marked deterioration of habitat conditions for riverine biota

u and th concentrations and isotope ratios in modern carbonates and waters from the bahamas the short residence times of th and pa in seawater make them very responsive to changes in the ocean environment we use a new multi ion counting technique to make th and pa isotope measurements in seawaters from a near shore environment in which oceanic chemical tracers are not overwhelmed by terrestrial inputs the bahamas an unusual feature of the bahamas setting is the shallow depth of water residing on the bank tops these waters have significantly lower 232th 230th 10 000 than those immediately adjacent to the banks 24 000 31 000 and a 231pa 230th near the production ratio 0 1 the change in 232th 230th and 231pa 230th on the bank tops is explained by almost quantitative removal of th and pa by scavenging and their replacement with a mixture of 230th and 231pa alpha recoiled from the underlying carbonates together with th from dust dissolution analysis of a water profile in the tongue of the ocean which separates the great and little bahama banks allows us to trace the movement of bank top water to depth a distinct minimum in both 232th 230th 13 000 and 231pa 230th 0 5 is observed at 430 m and is interpreted to reflect density cascading of bank top water with entrained carbonate sediment these results suggest that th and pa can be used as water mass tracers in near shore environments uranium concentration measurements on the same waters demonstrate that u is conservative across a range in salinity of 2 psu with a concentration of 3 33 ppb at a salinity of 35 the incorporation of u and th isotopes into marine carbonates has also been assessed by analyzing carbonate samples from the same location as these bahamas waters such incorporation is critical for u th geochronology u isotope analyses demonstrate that seawater 234u averages 146 6 and does not vary by more than 2 5 o and that carbonates capture this value additional high precision measurements 1 o on modern carbonates confirm that all oceans have identical 234u modern marine carbonates are shown to have 232th 230th ratios that reflect the local seawater in which they formed

paradise and herrin lost marginal depositional settings of the herrin and paradise coals western kentucky coalfield abstract this is the fourth installment in a series of papers on the asturian westphalian d disrupted mire margins termed the ragged edge in previous papers and limestone distributions in the herrin baker coal interval in the western kentucky extension of the illinois basin new data indicating in situ peat development and marine influence collected from the first in mine exposure of this interval are presented borehole data from the region are examined in the context of ragged edge exposures and a carbonate platform depositional model for this portion of the illinois basin is presented this shows that deposition of the sequence was influenced both by the underlying sediments and by a marine transgression the former influence is seen in variations in coal and limestone thickness over sandstone filled channels versus over shale bayfill deposits the latter is marked by the progressive upwards loss of coal benches i e the bottom bench of both coals is the most extensive and the herrin coal is more extensive than the overlying paradise coal and by marine partings in both coals further the brecciated margins seen in both coal seams are similar to brecciated peats encountered along the everglades margins of southwest florida overall coal distributions are similar to both those along the everglades margins and those along a transect from the belize coast to ambergis caye

notes on the origin of inertinite macerals in coals observations on the importance of fungi in the origin of macrinite macrinite is a generally rare inertinite maceral often incorporating remnants and fragments of other macerals including vitrinite liptinite and other inertinite the associated inertinites include multiple forms of funginite funginite is also commonly found in association with vitrinite of slightly elevated reflectance and with degraded varieties of vitrinite together with the highly degraded macrinite the latter two associations are here inferred to be part of a continuum of fungal and microbial degradation of peat in any case the origin of some macrinite is potentially distinct from that of inertinite generated by fire

macrinite forms in pennsylvanian coals abstract fungi are not as evident in pennsylvanian coals as in younger mesozoic or cenozoic coals however macerals formed through the interaction of fungi with woody and herbaceous precursors do occur one example of this is in some forms of the maceral macrinite this study analyzes macrinite forms from geographically distinct pennsylvanian coals the macrinite observed in this study is characterized by the presence of inclusions of other detrital macerals indicative of ingestion and excretion similar to that documented in macrinite of younger coals this suggests that while not all ecologic niches in the pennsylvanian were filled in the same manner as in younger settings similar processes implying similar types of interactions between fungi bacteria and fauna were producing similar products

twentieth century channel change on the dunajec river southern poland patterns causes and controls abstract spatial and temporal patterns of the twentieth century channel changes of the dunajec the second largest river of the polish carpathians are analysed using data from six historical maps hand auger drillings in paleochannels and hydrometric data from 10 gauging stations in its lower course the river was considerably narrowed shortened and embanked between the 1880s and the 1920s here bed degradation commenced in the late 19th century and has so far resulted in 3 1 m of channel incision in the middle river course little change occurred in mountain reaches where the dunajec is confined by valley sides and where bedrock exposures prevent channel incision in the reaches within intramontane basins channelization works carried out in the 1950s 1970s considerably narrowed the river and transformed its multi thread channel into a single thread straight channel rapid bed degradation induced by the works resulted in up to 2 m of channel incision over the second half of the century upstream progression of bed degradation into the adjacent mountain reach was hindered by bedrock exposures at its downstream end in the upper river course reaches with the deeply incised channels up to 3 5 m prevail over a few past decades in response to gravel exploitation river channelization and a reduction in catchment sediment supply more scarce are vertically stable reaches which owe their stability to low unit stream power in wide unmanaged reaches and to fixing of the channel bed by drop structures in channelized reaches this study shows that despite the overall tendency to incision over the 20th century considerable differences in the timing and course of channel changes occurred between particular river reaches due to variable human impact and local geological and geomorphological conditions the main phase of channel incision took place progressively later in the upstream direction however upstream progression of bed degradation from the already incised downstream reaches was precluded by the roznow dam and bedrock controlled reaches where bed material flushed out from an incising upstream reach had been introduced into an artificially narrowed channel of high transport capacity it was easily transferred downstream and could not restore the downstream reach to its pre channelization vertical position

oceanic 231pa 230th ratio influenced by particle composition and remineralization abstract we have investigated the role of particle compositions in affecting the distribution of 231pa and 230th in the ocean by separating sediments collected by sediment traps and cores into three size fractions and analyzed for their excess 231pa 231paex excess 230th 230thex and major chemical components the samples came from stations along 140 w in the equatorial pacific and from the blake outer ridge in the north atlantic results indicate that aluminosilicates clays are the major carrier of 231pa and 230th and the ratio 231paex 230thex in marine particulates decreases with increasing 232th concentration model simulation shows that sea floor sediments and trap collected particles have similar 231paex 230thex ratios in their biogenic components which are very close to the seawater ratio but are about one order higher than the ratios in coexisting clays preferential scavenging of 230th over 231pa by clays is primarily responsible for the 231pa 230th fractionation in the ocean the fractionation factor between 230th and 231pa fth pa varies from 10 for aluminosilicates to 1 for biogenic 232th free particles changes in fth pa as a function of particle composition exert primary controls on 231paex 230thex in marine particulates and bottom sediments and on the boundary scavenging of pa remineralization of biogenic particles in the water column may result in a decrease of 231paex 230thex our observations place an important constraint on the use of sediment 231paex 230thex as a paleoproductivity proxy namely in order to use down core variations of 231paex 230thex to assess past changes in surface productivity one must either verify or assume that the lithogenic particle flux and water column particle remineralization have remained essentially constant at the core site

geochemistry of the pond creek coal bed eastern kentucky coalfield the pond creek coal bed middle pennsylvanian breathitt formation is an important low sulfur resource in pike and martin countries in the eastern kentucky coalfield the mined area is crossed by the n20 e trending belfry anticline the pond creek coal bed has a higher sulfur content on the west side of the anticline the vertical trends in the ash geochemistry also vary across the anticline the sites to the east of the anticline represent deposition of peat through periods of relative stability with slow deposition bright lithotypes interspersed with periods of relatively rapid clastic deposition dull lithotypes both generally removed from marine influence comparison of elemental trends between the lowest bright lithotype and the second bright lithotype suggest that the swamp became less acidic with time an upward decrease in minor element concentration may be related to the influx of clays and other silicates present in the bone lithotype this bone may have acted as a relatively low nutrient soil for the growth of the plants which contributed to the overlying bright lithotype the sites to the west of the anticline were subjected to a greater marine influence than the eastern sites high k2o al2o3 ratios at the bottom and top of the coal bed and a high tio2 zr dull clarain near the bottom of the coal point to clastic influences on the geochemistry the relatively high cao percentages in the middle third of the coal bed suggest deposition at near neutral ph the upper third of the coal bed was dominated by syngenetic and epigenetic pyrite emplacement

an investigation of wulantuga coal cretaceous inner mongolia macerals paleopathology of faunal and fungal invasions into wood and the recognizable clues for their activity coal macerals are the product of a complex series of decompositional and preservational pathways from living woody and herbaceous tissues to the variety of forms seen in coal the cretaceous wulantuga coal inner mongolia china offers an opportunity to observe a number of maceral forms resulting from these disparate pathways assemblages of coprolites within fusinite strongly suggest an origin related to arthropod ingestion and consequent in situ emplacement of the macrinitic coprolites within the damaged wood structure followed by combustion of the whole to achieve the observed reflectance

notes on the origin of altered macerals in the ragged edge of the pennsylvanian asturian herrin coalbed western kentucky the ragged edge of the herrin western kentucky no 11 coal bed has a variety of maceral textures and assemblages that do not fit in the conventional vitrinite and inertinite definitions as established by the international committee for coal organic petrology within a narrow zone at the marine margin of the coalbed the coal is brecciated and cemented by carbonate with some of the brecciated clasts metamorphosed to anthracite level vitrinite reflectances this is in contrast to the ambient high volatile c bituminous coal rank in the region low rank peat like textures are preserved in the clasts suggesting that the metamorphism took place soon after deposition of the peat geochemical and mineralogical evidences suggest that the increase in reflectance was the consequence of the channeling of hydrothermal fluids through the breccia the narrow zone of metamorphism and further the juxtaposition of breccia clasts of varying degrees of metamorphism suggest that the hydrothermal influx occurred at shallow depths of burial perhaps shortly following deposition of the peat

further examination of the ragged edge of the herrin coal bed webster county western kentucky coal field abstract the herrin western kentucky no 11 coal bed in the dixon 7 1 2 min quadrangle webster county kentucky displays another manifestation of the thinning margin of the coal bed previous studies in adjacent hopkins county have demonstrated that the coal is brecciated as the margin is approached the brecciated coal is not always thin 1 5 m of brecciated inertinite rich coal was previously described to the southeast of the present study area in general the brecciated coals are considerably thinner than the 1 5 2 m thick normal herrin coal both cores studied are thin 22 6 and 33 cm and display petrographic characteristics different from thicker herrin coals the cores described in the present study show some signs of brecciation in certain cases the fragmented macerals are cemented by exsudatinite multiple generations of pyrite mineralization were noted in one core with total sulfur exceeding 13 in the upper 8 48 cm lithotype overall the cores investigated in this study along with examples from previous studies illustrate the progression of the herrin coal from its absence either through nondeposition or erosion through thin brecciated coals to mineable coals no other economic coal in western kentucky shows as many examples of the depositional edge as does the herrin all of the examples studied are from cores emphasizing the need to study more than just the thick mineable coals if the total extent of the coal body is to be understood

230th in the andaman sea rapid deep sea renewal 1 230th activities were determined in seawater collected from the bay of bengal and the andaman sea the andaman sea is a semi closed basin that is isolated from the bay of bengal by the andaman nicobar ridge the noticeable trend in the vertical distribution of 230th activity in the andaman sea is its uniformity below 1250 m depth we applied the scavenging mixing model to this vertical profile in the andaman sea and estimated the upper limit of renewal time to be 6 yr we compared 210pb 226ra ratios among deep waters of various oceanic basins to constrain the application of 230th as a tracer of deep water renewal the 210pb 226ra ratios were almost identical for the deep water of the andaman sea and the inflow water from the bay of bengal suggesting that the deep water in the andaman sea is replaced rapidly without bottom scavenging effects on the 210pb 226ra ratio

brecciated and mineralized coals in union county western kentucky coal field abstract coals from the d 2 and d 3 boreholes in the grove center 7 1 2 min quadrangle union county ky have been found to be highly brecciated and mineralized the mineralization is dominated by a carbonate assemblage with minor sulfides and sulfates included among the secondary minerals is the lead selenide clausthalite overall the emplacement of secondary vein minerals was responsible for raising the rank of the coals from the 0 6 0 7 rmax range found in the area to as high as 0 95 0 99 rmax a 1 3 m thick coal found in one of the boreholes is unique among known western kentucky coals in having less than 50 vitrinite semifusinite and fusinite dominate the maceral assemblages the coal is also low in sulfur coal which is unusual for the illinois basin it has an ash yield of less than 10 much of it dominated by pervasive carbonate veining the age of the thick coal in core d 2 is similar to that of the elm lick coal bed found elsewhere in the western kentucky coalfield the coals in d 3 are younger having stephanian palynomorph assemblages

protactinium 231 dating of carbonates by thermal ionization mass spectrometry implications for quaternary climate change measurement of protactinium 231 231pa in carbonates by thermal ionization mass spectroscopy yields 231pa ages that are more than 10 times more precise than those determined by decay counting carbonates between 10 and 250 000 years old can now be dated with 231pa methods barbados corals that have identical 231pa and thorium 230 230th ages indicate that the timing of sea level change over parts of the last glacial cycle is consistent with the predictions of the astronomical theory two devils hole calcite subsamples record identical 231pa and 230th ages suggesting that the chronology of this climate record is accurate

geomorphic diversity in the braided wandering bela river slovak carpathians as a response to flood variability and environmental changes abstract changes in the morphological pattern of the gravel bed bela river slovak carpathians were investigated to infer about the impact of flood events and environmental changes on the evolutionary trend of the river since the mid twentieth century the post flood period serial geomorphic analysis popsega approach coupled with gis analysis was used to identify morphological changes that occurred during particular flood periods the study focused on assessing how six flood periods fp with differing flood characteristics have influenced the evolutionary trend of the river several sets of aerial photos 1949 1961 1973 1986 1992 2003 2009 taken after the periods with the occurrence or lack of major floods provided data about channel landform changes in 227 river segments of 100 m length a decreasing trend of the area of the river s active zone from 2 5 km2 in 1949 to 1 4 km2 in 2009 was identified the first fp 1949 1961 with a very high magnitude flood in 1958 ri50 was characterized by increasing total channel length island number area and the number density of confluence diffluence pairs nodes and by decreasing bar area during this fp the frequency of cores of channel dynamics as well as the shannon s index of landforms diversity reached the highest values the following fp 1962 1973 with four 5 to 10 year floods exhibited the inverse pattern of changes in channel form parameters although the core frequency of channel dynamics and shannon s diversity index were still high the river system seems to have been relatively stable between 1974 and 1986 third fp with some decrease in the area of channel forms and in pattern metrics values during the fourth fp 1987 1992 several 1 5 to 3 year floods occurred and were associated with a decrease in some channel forms and a further decrease of the pattern metrics values an increase in all analysed channel parameters especially bar area and pattern metrics values occurred in the years 1993 2002 fifth fp as a consequence of two floods of moderate magnitude in 1997 ri7 and 2001 ri3 5 the lowest values of bar area and pattern metrics during the whole study period were recorded during the last fp 2002 2008 whereas island area increased at that time the study shows that the occurrence of floods during the last six decades has not returned the bela to its former state because of the overall decrease in flood magnitudes changes in catchment sediment supply induced by the increasing forest cover in the catchment from 22 7 in 1957 to 34 8 in 2008 and changes in channel boundary conditions channelization channel incision small hydropower plant constructions

log transport and deposition in incised channelized and multithread reaches of a wide mountain river tracking experiment during a 20 year flood abstract distance of large wood transport during floods and conditions for wood deposition in wide mountain rivers are still insufficiently understood tracking of logs tagged with radio transmitters was used to investigate differences in depositional conditions and the length of log displacement during a 20 year flood between channel reaches of different morphology in the czarny dunajec river polish carpathians during the rising limb of the flood logs were placed into the river at three locations at the beginning of an incised reach close to the beginning of a channelized reach and 1 km upstream from the beginning of a wide multithread reach the incised channelized and multithread reaches retained 12 5 33 and 94 of tagged logs introduced to these reaches respectively and of the logs retained in the multithread reach all were deposited in its upstream half significant differences in the length of displacement existed between the logs delivered to the river at the three locations with logs placed into the river at the beginning of the incised reach moving the longest distance and those delivered just upstream from the multithread reach moving the shortest distance before deposition one fourth of the logs were deposited in a low flow channel or on a channel margin one fifth on the floodplain and more than half on gravel bars after the flood river cross sections with deposited logs and a set of cross sections without any wood deposits were surveyed to collect data for one dimensional modelling of hydraulic conditions at the flood peak the cross sections with deposited logs were typified by significantly greater flow width and flow area and by significantly smaller mean flow depth mean velocity froude number mean bed shear stress and unit stream power principal component analysis of the hydraulic parameters in the analysed cross sections grouped the two types of cross sections in distinct clusters indicating that multithread cross sections differed in hydraulic parameters from all the other cross sections the experiment confirmed findings from the previous wood inventory and numerical modelling of wood transport and deposition in the river indicating that in a wide mountain river wood can be transported long distances in a narrow single thread channel it is however preferentially deposited in a wide multithread channel that functions as a natural wood trap preventing or considerably limiting further transfer of large wood to vulnerable sites therefore it is crucial to avoid channelization of multithread reaches that would eliminate their functioning as natural wood traps the hydraulic modelling provided a physical justification for the observed differences in wood behaviour between the distinct channel morphologies

scavenging of thorium in the ocean the distributions of th isotopes in both suspended participate matter and sea water were measured in the western north pacific and japan sea suspended particulate matter was collected simultaneously on four 142 mm diameter nuclepore filters 1 0 m in pore size by using an in situ deep sea pumping system particle associations were found to be 6 40 for 228th 9 52 for 230th and 9 72 for 232th with mean values of 26 32 for all three isotopes in order to explain the observed th isotope distributions in the pacific a reversible exchange model was developed that includes two classes fine and large of particle population in the ocean the fine particles are defined as those collected by filtration and comprising most of the standing crop of particles in seawater with no significant settling flux the large particles on the other hand are defined as those collected via sediment traps and represent a negligible standing stock in the water but play a predominant role in the vertical flux the model calculation suggests that the transfer of th from solution to fine particles is controlled by an adsorption desorption process which depends upon the chemical reactivity of elements aggregation of fine particles to fast sinking large particles was estimated to occur throughout the water column on a time scale of one to five months the large aggregates seem to disintegrate on a time scale of less than a few days suggesting their extremely fragile nature

hillslope deposits in gravel bed rivers and their effects on the evolution of alluvial channel forms a case study from the sudetes and carpathian mountains this paper describes initiation and development of specific alluvial channel forms connected with the supply of coarse grained hillslope sediment the study was carried out in gravel bed rivers located in mid mountain areas the sudetes and the carpathian mountains in central europe in the river channels studied where input of hillslope material is abundant patterns of sedimentation and erosion are determined by hillslope processes two types of primary sediment source in mountain temperate rivers with flat valley floors were identified mass movements in particular landslides and supply of angular coarse grained slope material to streams from cut bank sections the introduced coarsest hillslope sediment is only entrained during floods which destabilize the river systems downstream of the supply points at these river channel sections development of new and transformation of existing alluvial channel forms is observed sediment accretion and progradation of bars downstream of the hillslope sediment delivery zones hsd zones is connected with activity of these zones frequency of hillslope sediment supply size of coarse grained angular deposits introduced into the river channels and frequency of flood events the largest depositional forms such as gravel rich debris longitudinal bars lateral bars with a rock block core and lateral bars downstream of an hsd zone comprise coarse usually gravel sized sediment the main feature of their initiation and progradation is deposition of large rock blocks within or at a short distance downstream of the supply points lateral sediment accretion of the bars leads to river channel constriction during subsequent floods and development of other alluvial channel forms such as transverse gravel rich debris ribs diffuse gravel rich debris sheets side debris bars and small sandy rich gravel separation bars these forms create depositional complexes which are observed in the river channel within the zone of the hillslope sediment supply and for a few hundred meters downstream

channel response to sediment wave propagation and movement redwood creek california usa redwood creek north coastal californa usa has experienced dramatic changes in channel confguation since the 1950s a series of large floods in 1955 1964 1972 and 1975 combined with the advent of widespread commercial timber harvest and road building resulted in extensive erosion in the basin and contributed high sediment loads to redwood creek since 1975 no peak flows have exceeded a 5 year recurrence interval twenty years of cross sectional survey data document the downstream movement of a sediment wave in the lower 26 km of this gravel bedded river at a rate of 800 to 1600 m a i durng this period of moderately low flows higher transit rates are associated with reaches of higher unit stream power the wave was initially deposited at a site with an abrupt decrease in channel gradient and increase in channel width the amplitude of the wave has attenuated more than i m as it moved downstream and the duration of the wave increased from eight years upstream to more than 20 years downstream channel aggradation and subsequent degradation have been accommodated across the entire channel bed channel width has not decreased significantly after initial channel widening from large 25 year recurrence interval floods three sets of longitudinal surveys of the streambed showed the highest increase in pool depths and frequency in a degrading reach but even the aggrading reach exhbited some pool development through time the aggraded channel bed switched from functioning as a sediment sink to a significant sediment source as the channel adjusted to high sediment loads from 1980 to 1990 sediment eroded from temporary channel storage represented about 25 per cent ofthe total sediment load and 95 per cent of the bedload exported from the basin

precise timing of the last interglacial period from mass spectrometric determination of thorium 230 in corals the development of mass spectrometric techniques for determination of 230 th abundance has made it possible to reduce analytical errors in 238 u 234 u 230 th dating of corals even with very small samples samples of 6 x 10 8 atoms of 230 th can be measured to an accuracy of 3 percent 2 and 3 x 10 10 atoms of 230 th can be measured to an accuracy of 0 2 percent the time range over which useful age data on corals can be obtained now ranges from about 50 to about 500 000 years for young corals this approach may be preferable to 14 c dating the precision with which the age of a coral can now be determined should make it possible to critically test the milankovitch hypothesis concerning pleistocene climate fluctuations analyses of a number of corals that grew during the last interglacial period yield ages of 122 000 to 130 000 years the ages coincide with or slightly postdate the summer solar insolation high at 65 n latitude which occurred 128 000 years ago this supports the idea that changes in pleistocene climate can be the result of variations in the distribution of solar insolation caused by changes in the geometry of the earth s orbit and rotation axis

river response to channel regulation case study of the raba river carpathians poland processes induced by the channelization of the raba river in the present century are examined to illustrate the response of a gravel bed stream following narrowing and straightening of its channel up to 3 m of incision has occurred the change from a slow and relatively steady degradation in the lower reaches to separate degradation events in the higher reaches is attributed to the differential rate of headcut retreat and to the control exerted by mid channel bars upon the rate of river energy dissipation progressive outwashing of finer grains from bed material has followed the diminishing sediment yield of the basin and the increase in stream power the ensuing growth in mean grain size and changes in sediment fabric have increased boundary resistance to flow and reduced particle susceptibility to entrainment downstream magnification of peak discharges has become increasingly pronounced with the advancing incision the decrease in flood plain storage and self acceleration of flows passing the relatively deep and straight channel has caused flood waves to become progressively more flashy in nature an increase in channel depth and reduction in gradient caused by downward and backward erosion as well as bed material coarsening has promoted the re establishment of an equilibrium conversely flow velocity increases due to flow concentration in the deepened channel reduction in grain mobility allows the river to attain a new equilibrium at flow velocity and stream power levels higher than before the channelization numerous disadvantages of the applied regulation scheme and its failure to reduce flood hazard raise the question of its maintenance to be successful any regulation design must take into account changes in sediment supply and flood hydrographs resulting from the simultaneous alterations in basin management

river adjustment to changes in sediment load the effects of tin mining on the ringarooma river tasmania 1875 1984 the mining of alluvial tin in the ringarooma basin began in 1875 reached a peak in 1900 20 and had virtually ceased by 1982 during that time 40 million m3 of mining waste were supplied to the main river quickly replacing the natural bed material and requiring major adjustments to the channel based on estimates of sediment supply from more than 50 widely scattered mines and the frequency of flows capable of transporting the introduced load the river s transport history is reconstructed using a mass conservation model because of the lengthy time period 110 years and river distance 75 km involved the model cannot predict detailed change but it does reproduce the main pattern of sediment movement in which successive phases of aggradation and degradation progress downstream peak storage is predicted in that part of the river where braiding and anastomosis are best developed aggradation was most rapid in the upper reaches close to major supply points becoming slower and later with distance downstream channel width increased by up to 300 per cent where the valley floor was broad and braiding became relatively common bridges had frequently to be replaced while bed levels were still rising in lower reaches degradation began in upper ones notably after 1950 and by 1984 had progressed downriver over 30 km rates of incision reached 0 5 m yr 1 especially in the early 1970s when record high flows occurred as a result of degradation the bed material became gravelly through either reexposure of the original bed or lag concentration of coarser fractions also a narrower unbraided channel has developed the river is beginning to heal itself and upper reaches now have reasonably stable beds but at least another 50 years will be required for the river to cleanse its channel of mining debris

coal facies studies in the eastern united states coals in the eastern united states east of the mississippi river have been the subject of a number of coal facies studies going back to the 19th century such studies would not necessarily fall within a strict modern classification of coal facies studies but if a study encompassed some aspects of paleobotany palynology petrology geochemistry or sedimentology we assumed that some data and interpretations may be of use in evaluations of the facies references are presented as a guide for further research with annotation in the tables

complex transformation of the geomorphic regime of channels in the forefield of the moravskoslezske beskydy mts case study of the moravka river czech republic abstract this paper presents a complex analysis of both the contemporary and the historic development of the geomorphic regime of the transformed reach of the moravka river in the czech carpathians the assessment concentrates on the conditions and causes of the channel development in the last c 200 years compared with the state of european channels especially those of the carpathian zone the moravka r pattern has undergone a rapid change in the last 50 years particularly in connection with the active channel narrowing and massive incision the original anabranching river pattern has gradually been replaced by a simple narrowed channel incised into the bedrock the average width of the moravka r active channel changed from 153 m in 1836 1852 and 165 m in 1876 1878 to 44 m in the year 2010 at some parts the original river bed has lowered as much as 8 m in the last 40 years which indicates an incision rate of 12 24 cm year these changes have been caused by strong anthropogenic impacts in the form of the river channel control bank stabilisation and weir and valley dam construction other reasons are related to land cover and land use changes a great influence on the contemporary processes is also exerted by the geological predisposition of the carpathian flysch lithology in channel bedrock particularly the occurrence of claystone layers that present little resistance to water erosion currently the deficit of transportable sedimentary material along with the increased transport capacity of the incised river bed has generated conditions for constantly intensifying erosion processes in the moravka r channel

removal of 230th and 231pa at ocean margins abstract uranium thorium and protactinium isotopes were measured in particulate matter collected by sediment traps deployed in the panama basin and by in situ filtration of large volumes of seawater in the panama and guatemala basins concentrations of dissolved th and pa isotopes were determined by extraction onto mno 2 adsorbers placed in line behind the filters in the in situ pumping systems concentrations of dissolved 230 th and 231 pa in the panama and guatemala basins are lower than in the open ocean whereas dissolved 230 th 231 pa ratios are equal to or slightly greater than ratios in the open ocean particulate 230 th 231 pa ratios in the sediment trap samples ranged from 4 to 8 in contrast to ratios of 30 or more at the open ocean sites previously studied particles collected by filtration in the panama basin and nearest to the continental margin in the guatemala basin contained 230 th 231 pa ratios similar to the ratios in the sediment trap samples the ratios increased with distance away from the continent suspended particles near the margin show no preference for adsorption of th or pa and therefore must be chemically different from particles in the open ocean which show a strong preference for adsorption of th ocean margins as typified by the panama and guatemala basins are preferential sinks for 231 pa relative to 230 th furthermore the margins are sinks for 230 th and to a greater extent 231 pa transported by horizontal mixing from the open ocean

islands in a european mountain river linkages with large wood deposition flood flows and plant diversity abstract vegetated islands are characteristic landforms of braided mountain rivers long term observations and recent morphological and botanical surveys conducted in the gravel bed czarny dunajec polish carpathians were used to determine the processes and patterns governing initiation and development of islands and their floristic complexity moreover dendrochronologically estimated years of island inception were compared with the timing and magnitude of flood flows in the period 1970 2011 to infer about controls on the formation and persistence of islands in the river in the high energy braided river islands originate as a result of deposition of large vegetative particles mostly large wood on gravel bars and the associated vegetative regeneration of living wood or the growth of seedlings and saplings in the shelter of wood accumulations tree ring dating of the largest trees growing in particular zones of building and established islands indicated a predominant upstream island growth in the river it results from repeated accumulation of living wood on the head of islands and its subsequent regeneration and contrasts with the progressive downstream growth of islands in the rivers supplied with large stable logs of the tree species without the capability to re sprout the lack of islands from the years 1982 1996 most likely reflects the removal of relatively young islands by two major floods in the 1990s which were however unable to destroy older and larger islands after 1997 the occurrence of low to moderate floods facilitated the formation and persistence of islands the plant inventory demonstrated that species richness increased non linearly with the increasing age area and shoreline length of islands islands supported more plant species than the riparian forest and attained comparable species richness at an early stage of development fast developing dynamic and supporting rich plant communities islands contribute highly to the overall floristic complexity of the river corridor and their re establishment should be viewed as an important factor in the restoration of hydromorphologically degraded mountain rivers

patterns of alluvial rivers the pattern planform of a river can be considered at vastly different scales depending upon both the size of the river and the part of the fluvial system that is under consideration figure 1 for example in the broadest sense river patterns comprise a drainage network dendritic parallel trellis etc figure la the type of pattern is of interest to geomorphologists and geologists who interpret geologic conditions from aerial photographs at another scale a river reach which in figure lb is meandering is of interest to the geomorphologist who is interested in what that pattern reveals about river history and behavior and to the engineer who is charged with maintaining navigation and preventing major instability when a single meander is examined figure 1 c the hydraulics offtow the sediment transport and the potential for bank erosion are of concern in addition the sedimentologist is interested in the distribution of sediment within the bend bed forms within the channel figure ld and sedimentary structures figure ie which also establish a component of roughness for the hydraulic engineer finally the individual grains figure if provide geologic information on the sediment sources the nature of sediment loads and the feasibility of dredging for gravel there is an interaction of hydrology hydraulics geology and geomorphology at all scales which emphasizes the point that the fluvial system as a whole cannot be ignored even though only a component of the system is to be studied in this review only the patterns or planforms of alluvial rivers are discussed although it is apparent that the hydrologic and sediment yield characteristics of the drainage basin figure la as well as its geologic history cannot be ignored in the explanation of the pattern of any river

threshold of coarse sediment transport in broad and narrow natural streams the threshold of coarse sediment transport has been examined in natural streambeds in an upland pennine u k area threshold values of the total boundary shear stress t0 for a given grain size in a narrow natural stream w d 11 efficiency in the entrainment process is related not only to the overall channel geometry but also varies as a function of discharge in channels characterized by compound roughness empirical curves relating t0 and a mean grain size d5 are presented but are limited in application to streams of similar physical and hydraulic characteristics as the ones examined in this investigation considerable divergence is noted between these empirical functions and a summary empirical function for general application obtained from a published source the reasons for this divergence are discussed the influence of grain shape was found not to be important in the initiation of motion criterion this conclusion may reflect the limited range of natural grain shapes in the study streams but might reasonably apply to other field investigations of similar streams modifications of the shields and yalin diagrams are suggested for practical applications in shallow streams with poorly graded bed material the shields parameter may be regarded as an inverse function of the relative protrusion of individual grains in the shallow flow depth d5 d the increased importance of augmented drag forces in the entrainment process in shallow flows is suggested as the physical explanation for the reduced values of the shields parameter however the relationships presented should not be applied to laboratory experiments concerned with well graded sediments therefore beds with little deviation in level in which the shields parameter may be regarded as constant at high reynolds grain numbers consistent estimated field values of a threshold sediment transport parameter might be used to compare field data to threshold values derived from statistical arguments and laboratory experiments reported in the literature

sediment supply and the development of the coarse surface layer in gravel bedded rivers the bed surface of most gravel rivers is considerably coarser than the sub surface or the gravel load transported over it a phenomenon affecting river dynamics morphology and ecology the coarse surface layer often called an armour or pavement has been attributed to an inherent tendency for small grains to settle between larger ones during active transport of all sizes1 2 and to selective erosion or trapping of finer particles when the coarse grains are relatively immobile3 4 where bedload supply is cut off below dams selective erosion causes coarsening5 6 using a simple quantitative model we propose that surface coarsening develops in gravel bedded rivers when local bedload supply from upstream is less than the ability of the flow to transport that load we present laboratory results which support this hypothesis and show that supply reduction causes changes in bedforms and progressive confinement of active bedload transport to a narrow band of finer bed surface bordered by a coarse less active bed it may therefore be possible to relate the degree of river bed surface coarsening to sediment supply resulting from land use

the distribution of 230th and 231pa in the deep sea surface sediments of the pacific ocean in order to determine the areal extent and distribution of 231pa sinks in the pacific ocean we have analyzed 34 deep sea surface sediment samples from widely distributed locations for their pa th and u isotopes while the 230thxs content varies by more than a factor often the 231paxs content is confined in a relatively narrow range with a mean value of 2 8 1 4 dpm g there is a positive correlation between 230thxs and 231paxs and using the regression line it is possible to calculate the 230thxs231paxs activity ratios in samples for which only 230th data are available we then constructed a map of 230thxs231paxs distribution using 230paxs231paxs 11 the production ratio in the water column as a criterion for identifying preferential 231pa sinks we have identified an area covering 30 40 of the pacific ocean this area includes most of the pacific margins the northwest pacific the antarctic ocean and perhaps the mid ocean ridge regions and is nearly coincident with that of high sediment accumulation rates this suggests that the paniculate flux is important for the removal of 231pa from the ocean two models for the removal of 231pa produced in the open ocean are 1 1 lateral transport into the vertical flux in regions of high particulate flux damaster 1979 andersonet al 1983a b or 2 2 uptake at the sediment water boundary the second model is more likely to be correct to distinguish unequivocally between the two proposed models we would need sediment trap data for the western north pacific

the influence of river training on mountain channel changes polish carpathian mountains the purpose of this paper is to explain the influence of river training on channel changes in mountain rivers also considered are the causes of failure of different training schemes the research was conducted on the regulated mszanka and porebianka rivers belonging to the raba river drainage basin in the polish flysh carpathian mountains channel mapping carried out in 2004 drew attention to the contemporary morphology of the channels and the development of their dynamic typology general changes in channel morphometry and land cover were identified by comparing cartographic sources from various years archive material from cracow s regional water management authority rzgw was used to analyse the detailed channel changes caused by each regulation structure the material consisted of technical designs of individual training works as well as plans longitudinal profiles and cross sections of trained channel reaches a series of minimum annual water stages at the mszana dolna gauging station was used to determine the tendency of channel bed degradation over 53 years during the first half of the 20th century the middle and lower courses of the mszanka and porebianka rivers had braided patterns the slopes mostly covered with crops were an important source of sediment delivery to the river channels today both channels are single threaded narrow and sinuous downcutting is the leading process transforming the channels they cut down to bedrock along about 60 of their lengths the main type of channel is an erosion channel which occurs also in the middle and lower courses of the rivers the channel sediment deficit is an important cause for river incision sediment supply to the channels was reduced after a replacement of crops on the slopes by meadows or forests gravel mining has also caused channel downcutting the rapid channel changes began after 1959 as systematic training was introduced channel regulation seems therefore to be a major factor determining channel adjustment debris dams and groynes were built before 1980 and these caused the greatest change of channel pattern increase of channel gradient and magnitude of river incision after that date the measures mostly involved drop structures from then on the rate of downcutting decreased considerably but has not ceased the rivers continued to incise until bedrock was exposed or training structures were destroyed after that a tendency to lateral migration and local braiding were observed in the deepened channel the channels displayed a tendency to return to their morphology and dynamic from before the training the results demonstrate that river training distorts the equilibrium of channel systems a channel becomes divided into artificial reaches which later follow different evolutionary patterns most training schemes on mountain channels are ineffective in the long term as river managers seem to consider a channel at a reach scale only individual channel reaches however are not independent but rather form a system that must be managed at the entire channel scale

enhanced scavenging of 231pa relative to 230th in the south atlantic south of the polar front implications for the use of the 231pa 230th ratio as a paleoproductivity proxy abstract the fractionation of 230th and 231pa was investigated throughout the atlantic sector of the southern ocean published scavenging models generally assume that the 231pa 230t ratio of surface sediments is primarily determined by the mass flux of particles this relationship holds north of the polar front where low primary productivity coincides with ratios of unsupported 231pa 230th xs 231pa 230th in surface sediments below the production ratio of both radionuclides in the water column however we observed high xs231pa 230th ratios conventionally interpreted as a high productivity signal in surface sediments south of the polar front especially throughout the weddell sea in contradiction with the low particle flux of this region measurements of both dissolved and particulate fractions of 231pa and 230th in the water column revealed a strong n s decrease in the th pa fractionation factor from typical open ocean values around 10 north of the polar front to values between 1 and 2 south of 60 s this observation clearly indicates that the high xs231pa 230th ratios in surface sediments south of the antarctic circumpolar current are produced by a n s increase in the relative scavenging efficiency of 231pa relative to 230th most probably due to a change in the chemical composition of particulate matter and not by a high mass flux it is speculated that biogenic opal suggested not to significantly fractionate231pa and 230th may explain the enhanced scavenging of 231pa to the south this assumption is further supported by extremely high 231pa 230th ratios up to 0 34 in material collected with sediment traps south of the polar front where fluxes are primarily determined by biogenic opal based on these results we conclude that in regions where the sedimenting flux is dominated by biogenic opal the 231pa 230th ratio is not a reliable indicator for the mass flux of particles thus limiting its use as a paleoproductivity proxy in the southern ocean

radiocarbon decay and oxygen utilization in the deep atlantic ocean a parameter based on the sum of the concentrations of po4 and o2 divided by the redfield coefficient o2 po4 is used to separate the contributions of the northern and southern components to deep waters in the atlantic this separation allows the amount of radiocarbon lost by radiodecay and the amount of oxygen lost to respiration during residence in the deep atlantic to be calculated maps of these quantities reveal strong west to east gradients and weak north to south gradients consistent with ventilation along the western boundary from both ends of the ocean coupled with mixing outward from the boundary the o2 and 14c deficiences are highly correlated suggesting an o2 utilization rate of 12 m kg per century the apparent mean isolation time of water in the deep atlantic is about 200 years

high precision 230th and 232th in the norwegian sea and denmark by thermal ionization mass spectrometry seawater samples 1 2 liters were collected from the norwegian sea and denmark strait and analyzed for 230th and 232th using highly sensitive thermal ionization mass spectrometry tims depth profiles of dissolved 230th and 232th are characterized by surface water minima 1 fg kg 5 pg kg subsurface maxima 12 fg kg 134 pg kg and intermediate concentrations that progressively decrease toward the bottom 5 fg kg 17 pg kg respectively the lack of an increase in 230th with depth is suggested to result from the short ventilation age of norwegian sea deep water combined with enhanced scavenging near the basin margins the 230th maximum is attributed to advection of high 230th in the arctic intermediate water whereas the 232th maximum may be related to a particulate source the low dissolved 230th and 232th concentrations observed in the nadw formation regions implies a minor advective export of these long lived th tracers to the north atlantic

floods in mountain environments a synthesis floods are a crucial agent of geomorphic change in the channels and valley floors of mountains watercourses at the same time they can be highly damaging to property infrastructure and life because of their high energy mountain watercourses are highly vulnerable to environmental changes affecting their catchments and channels many factors have modified and frequently still tend to modify the environmental conditions in mountain areas with impacts on geomorphic processes and the frequency magnitude and timing of floods in mountain watercourses the ongoing climate changes vary between regions but may affect floods in mountain areas in many ways in many mountain regions of europe widespread afforestation took place over the twentieth century considerably increasing the amounts of large wood delivered to the channels and the likelihood of jamming bridges at the same time deforestation continues in other mountain areas accelerating runoff and amplifying the magnitude and frequency of floods in foreland areas in many countries in channel gravel mining has been a common practice during recent decades the resultant deficit of bed material in the affected channels may suddenly manifest during flood events resulting in the failure of scoured bridges or catastrophic channel widening during the past century many rivers in mountain and foreland areas incised deeply the resultant loss of floodplain water storage has decreased attenuation of flood waves hence increasing flood hazard to downstream river reaches on the other hand a large amount of recent river restoration activities worldwide may provide examples of beneficial changes to flood risk attained as a result of increased channel storage or reestablished floodplain water storage relations between geomorphic processes and floods operate in both directions which means that changes in flood probability or the character of floods e g increased wood load may significantly modify the morphology of mountain rivers but morphological changes of rivers can also affect hydrological properties of floods and the associated risk for societies this paper provides a review of research in the field of floods in mountain environments and puts the papers of this special issue dedicated to the same topic into context it also provides insight into innovative studies methods or emerging aspects of the relations between environmental changes geomorphic processes and the occurrence of floods in mountain rivers

distribution of 230th in the labrador sea and its relation to ventilation abstract measurements of dissolved and particulate230th and232th by thermal ionization mass spectrometry were made on samples collected from the labrador sea and the denmark strait and iceland scotland overflow waters the large scale feature of low and invariant230th evident in deep waters of the labrador sea and previously observed in the deep northern atlantic can be reproduced using a reversible scavenging model that includes the effect of ventilation advective transport also must be important in the redistribution of230th in other regions of the atlantic and for other long lived tracers such as231pa 26al and10be

constraints on deep water age and particle flux in the equatorial and south atlantic ocean based on seawater 231pa and 230th data high precision measurements of 231 pa and 230 th in filtered seawater and suspended particulate matter samples are reported for the equatorial and south atlantic distributions of 231 pa and 230 th clearly indicate the influence of advection as evidenced by departures from scavenging models that predict a linear increase with depth for these tracers application of a scavenging mixing model implies a deep water transit time of 60 100 years from the northern source water regions the average particulate 231 pa 230 th activity ratio is 0 0498 0 0160 a factor of 2 lower than the 231 pa 230 th production ratio of 0 093 and in agreement with reported excess 231 pa 230 th ratios of 0 06 0 004 in holocene sediments north of 50 s in the atlantic these water column data further suggest that lateral eddy diffusive transport combined with enhanced scavenging in high particle flux marginal regions boundary scavenging is weakly expressed in the atlantic particle fractionation of these tracers is also indicated by the elevated fractionation factors of f th pa 4 32 24 04 ave 9 97 4 98 compared to values of 1 4 in the southern ocean

anastomosis and the continuum of channel pattern anastomosing rivers are characterized by multiple channels separated by islands excised from the floodplain their status relative to the continuum concept of channel pattern is assessed with channel pattern defined in terms of three variables flow strength bank erodibility and relative sediment supply using an ordinal scaling l ow m oderate h igh the traditional forms of straight meandering and braided have respective representations of l l l m l m l m and h h m h in terms of those variables the anastomosing pattern is on average represented by l l m h but not so definitively as other forms specification of the third element sediment supply is particularly hampered by the paucity of data but aggradation a characteristic of many anastomosing rivers can be thought of as symptomatic of a moderately high rate of supply relative to the ability for onward transport a sufficiently high rate of supply to a channel with low flow strength and resistant banks would induce shoaling and or lateral constriction that locally forces flow out of the main channel and ultimately leads to the cutting of anabranches a flow regime characterized by concentrated floods of relatively large magnitude is also regarded as highly conducive to the formation of new channels where low bank erodibility constrains channel capacity anastomosis may in certain cases represent a transitional form of channel pattern but there is no denying the longevity of some anastomosing systems

environment friendly reduction of flood risk and infrastructure damage in a mountain river case study of the czarny dunajec abstract migration of a mountain river channel may cause erosional risk to infrastructure or settlements on the valley floor following a flood of 2010 a cutbank in one of the bends of the main channel of the czarny dunajec polish carpathians approached a local road by 50 m to arrest the erosion of the laterally migrating channel water authorities planned construction of a ditch cutting the forested neck of the bend reinforcement of the ditch banks and damming the main channel with a boulder groyne in order to avoid channelization of the highly valued multithread river reach that would deteriorate its ecological status and cause increased flood risk to downstream reaches an alternative approach to prevent bank erosion was proposed the new scheme applied in 2011 included opening of the inlets to inactive side braids located by the neck of the bend of the main channel this solution reestablished the flow in the steeper low flow channels allowing us to expect a cutoff and abandonment of the main channel during subsequent floods gravelly deflectors were constructed directly below the inlets to the reactivated side channels to divert the flow into the channels and prevent the water from entering the main channel hydraulic measurements performed before and after the implementation of the scheme confirmed that it enabled shifting the main water current with the highest average velocity and bed shear stress from the braid closest to the road to the most distant braid similar surveys of fish and benthic macroinvertebrate communities indicated that flow reactivation in the side channels was beneficial for these groups of river biota increasing their abundance and taxonomic richness in the reach not only was the implemented solution significantly less expensive but it also enhanced ecological functions of the multithread channel and the variability of physical habitat conditions and maintained the role of the reach as a wood debris trap however avulsion of the main channel in the river bend immediately upstream during the flood in may 2014 again caused erosional risk to the road although at another location this indicates that with the highly unstable multithread channel pattern of the czarny dunajec the best practice of river maintenance in a relatively unmanaged valley reach would be allowing free channel migration within the floodplain area and reinforcing where necessary the boundary between the erodible river corridor and the managed terrace

natural and anthropogenic radionuclide distributions in the northwest atlantic ocean we have used in situ pumps which filter large volumes of sea water through a 1 m cartridge prefilter and two mno2 coated cartridges to obtain information on dissolved and particulate radionuclide distributions in the oceans two sites in the northwest atlantic show subsurface maxima of the fallout radionuclides137cs 239 240pu and241am although the processes of scavenging onto sinking particles and release at depth may contribute to the tracer distributions comparison of predicted and measured water column inventories suggests that at least 35 50 of the pu and241am are supplied to the deep water by advection the depth distributions of the naturally occurring radionuclides232th 228th and230th reflect their sources to the oceans 232th shows high dissolved concentrations in surface waters presumably as a result of atmospheric or riverine supply activities of232th decrease with depth to values 0 01 dpm 1000 l 228th shows high activities in near surface and near bottom water due to the distribution of its parent 228ra dissolved230th produced throughout the water column from234u decay increases with depth to 3000 m values in the deep water 3000 m are nearly constant 0 6 0 7 dpm 1000 l and the distribution of this tracer and perhaps other long lived particle reactive tracers as well may be affected by the advection inferred from pu and241am data the ratio of particulate to dissolved activity for both230th and228th is 0 15 0 20 this similarity precludes the calculation of sorption rate constants using a simple model of reversible sorption equilibrium moreover in mid depths228th tends to have a higher particulate dissolved ratio than230th suggesting uptake and release of230th and228th by different processes this could occur if228th produced in surface water were incorporated into biogenic particles formed there and released as those particles dissolved or decomposed during sinking 230th produced throughout the water column may more closely approach a sorption equilibrium at all depths 230th 241am and239 240pu are partitioned onto particles in the sequence th am pu with 15 of the230th on particles compared with 7 for am and 1 for pu distribution coefficients kd are 1 3 1 6 107 for th 5 6 106 for am and 7 10 105 for pu the lower reactivity for pu is consistent with analyses of pu oxidation states which show 85 oxidized v vi pu however thekd value for pu may be an upper limit because pu like228th may be incorporated into particles in surface waters and released at depth only by destruction of the carrier phase

dynamic single thread channels maintained by the interaction of flow and vegetation most rivers on earth today flow as a single channel in some cases with occasional islands and follow a more or less sinuous course however single thread channels have proven difficult to reproduce and study experimentally experimental self formed channels tend to widen and subdivide leading to a braided pattern cohesive sediment has been the main mechanism studied for stabilizing banks and producing a single thread channel we show how laboratory experiments using vegetation to stabilize banks can organize the flow and convert the planform morphology from braided to single thread our experimental strategy a repeated cycle of short periods of high water discharge alternating with longer periods of low discharge accompanied by plant seeding and growth leads to the evolution of a dynamic self maintaining single thread channel with well defined banks and floodplain by eliminating weak flow paths the vegetation corrals the water into a single dominant channel until the reduction in total wetted width leads to a new self organized state in which the flow removes vegetated area as fast as it is produced the new channel is deeper and has a broader distribution of depths than the braided one with channel size adjusted to carry almost all the flood flow the resulting system maintains a dynamic steady state via similar mechanisms to those that operate in meandering channels in the field specifically erosion at the outside of bends bend growth and bar development our methodology provides a basis for experimental development of self sustaining high amplitude meanders and has applications for river management and basic research purposes

channel response to increased and decreased bedload supply from land use change contrasts between two catchments abstract the catchments of pine creek idaho usa 200 km 2 and the drome river in the drome department france 1640 km 2 illustrate contrasting changes in land use bedload sediment production and channel response hard rock mining began in the catchment of pine creek near the end of the 19th century and together with road construction timber harvest and historically heavy grazing of uplands resulted in increased tributary bedload yield increased bedload migrating to the channel combined with removal of large cedar trees on the floodplain resulted in channel instability which propagated downstream over a period of decades on many reaches of pine creek active channel width has increased by over 50 since 1933 over roughly the same time period the drome river catchment was extensively reforested after at least one century of denudation and heavy grazing and numerous check dams were constructed on torrents to reduce erosion as a result the drome river has experienced a reduction in bedload sediment supply since the late 19th century in addition gravel has been extracted from some reaches consequently the channel has degraded and gravel bars have been colonized with woody riparian vegetation channel widths in wide braided reaches decreased from 1947 to 1970 by 60 on pine creek channel instability has resulted in bank erosion exposing contaminated mine tailings and increased flood hazard on the drome river degradation has undermined bridges and embankments and lowered the water table in areas dependent on groundwater for irrigation resulting in loss of 6 million m 3 of groundwater storage since 1960 though they differ in drainage area by nearly an order of magnitude pine creek and the drome river provide an excellent contrast in that they represent two sides of an epicycle of alluvial sedimentation set off in each case by land disturbance in both cases the most recent channel changes though in opposite directions were viewed as negative by river managers on pine creek managers have removed or protected from erosion mine tailings and have attempted to train the stream into a more stable channel and most rock waste piles the principal sediment sources have recently been controlled on the drome river managers have prohibited gravel mining and adopted new policies to permit coarse sediment to migrate through the river system