historical environmental pollution trend and ecological risk assessment of trace metals in marine sediments off adyar estuary bay of bengal india geochemical mineralogical and textural analyses were carried out in core sediments off adyar estuary bay of bengal india to record the contamination trend from urban and industrial activities during the historical past quartz feldspar kaolinite chlorite and illite were the main lithogenic and clay minerals carbonate was the predominant biogenic mineral trace metals fe al cu cr ni pb and zn indicate more enrichment in the surface sediment layers due to recent anthropogenic activities the mean anthropogenic factor af values for trace metals in core sediments decreased in the following order cr ni zn cu pb the pollution load index pli values in adyar core sediments ranged from 1 to 1 25 with an average of 1 07 based on af pli and sediment quality guidelines values for trace metals significant metal enrichment and ecological risk were obtained in upper most sediment layer multivariate statistical methods such as correlation matrix principal component analysis and cluster analysis were carried out to find the relationships among the texture size metals and minerals the pollution of adyar estuarine sediments was started in the 1960s responding to the rapid economic development in chennai coastal and adyar estuarine region in the last five decades despite these high concentrations in the upper layer development and expansion of industries are still continuing the stricter regulations for the discharge and remediation of sediments are urgent for the conservation of environments and human health

interplay between detrital and diagenetic processes since the last glacial maximum on the northwest iberian continental shelf abstract integrated analyses of magnetic geochemical and textural data on six cores from the northwestern iberian continental shelf allowed the reconstruction of the paleoenvironmental evolution of this area since the last glacial maximum lgm four sedimentary units were identified representing a succession from fluvial and subaerial settings to high and finally low energy marine deposits subsequent to the post lgm sea level rise the uppermost unit was deposited during the holocene and its magnetic properties were controlled by the interplay between detrital input and early diagenetic reductive dissolution of magnetic minerals identification of a primary steady state early diagenetic signal allowed the recognition of periods of increased detrital input bounded by intervals of lower detrital input and intensified reductive diagenesis related to intensified upwelling in the area these paleoenvironmental alternations are consistent with the climatic evolution of the late holocene during the roman warm period and medieval warm period the combined effect of greater humidity and intense agricultural and mining activities led to a greater erosion and transport of detrital sediments to the shelf in contrast enhanced diagenetic reduction intervals caused by upwelling intensification were roughly coincident with the colder dark ages and the little ice age

negative estuarine circulation in the ria of pontevedra nw spain an along estuary negative circulation was measured in the ria of pontevedra nw spain on may 13 1998 this two layered circulation pattern with near bed water moving seaward and near surface water landward was generated by the existence of two different water masses at intermediate depths water in the inner part of the estuary was a mixture of estuarine water and eastern north atlantic central water enacw which had entered the estuary some days before due to an intense upwelling event water in the middle part of the estuary was a mixture of estuarine water and fresh water coming from the river discharge which had been higher during the days previous to may 13 this water mass distribution gave rise to the existence of denser water in the inner part of the estuary than in the middle one generating the observed negative circulation pattern

an inversion of the estuarine circulation by sluice water discharge and its impact on suspended sediment transport abstract the wadden sea is characterized by a complex topography of branching channels and intertidal flats in which the interplay between fresh water discharges wind forcing and the tidal current causes sediment transport rates and direction to be highly variable in space and time during three field campaigns indications of a negative estuarine circulation have been found in a channel adjacent to the coast in the western dutch wadden sea contrary to the classical picture of estuarine circulation a periodic density stratification was observed that builds up during flood and breaks down during ebb this can be related to a large freshwater source at the mouth of the channel the sluice in kornwerderzand in this study observations of this phenomenon are presented and with the help of a numerical model the different drivers for residual suspended matter transport in this area namely tidal asymmetries in the current velocity and the above mentioned periodic stratification are investigated it is found that the residual current in the area of interest points in ebb direction caused by both the elongated ebb flow phase and the periodic stratification on the contrary the stronger flood currents cause a transport of suspended matter in flood direction this transport is counteracted and therefore diminished by the effects of the sluice discharge

comparison between petroleum hydrocarbon concentrations and magnetic properties in chennai coastal sediments bay of bengal india abstract petroleum hydrocarbon concentrations phc of surface sediments along the chennai coast india were measured by uv fluorescence uvf spectroscopy and the results are expressed in terms of chrysene equivalents the concentration of phc in sediment varies widely from 1 88 ppm to 39 76 ppm as compared to the baseline 1 88 ppm with higher values obtained in the northern part of the study area the highest magnetic susceptibility 96 8 10 8 m 3 kg 1 value was determined from the chennai harbour area the magnetic parameters show that the chennai coastal sediments are dominated by ferrimagnetic minerals the positive correlation r 2 0 86 p arm and sirm covary with the petroleum hydrocarbon concentration suggesting that large amounts of magnetic minerals originate from anthropogenic activities it is evident that using magnetic measurements may be considered a simple rapid cheap and non destructive method to determine petroleum hydrocarbon concentrations in coastal sediments furthermore this technique may be applied to petroleum exploration studies magnetic susceptibility measurements in sediments have been proposed as complementary or alternative means of exploration and assessment of hydrocarbon reservoirs

multicomponent analysis of ftir spectra quantification of amorphous and crystallized mineral phases in synthetic and natural sediments abstract the study of weathering and erosion processes requires the establishment of a mass balance of minerals from the soils towards the sedimentation area this calls for the development of quantitative tools that can be applied to mixtures of finely divided and sometimes poorly crystallized minerals found in soils and sediments we present here the use of fourier transform infrared ftir absorbance spectroscopy in the mid infrared as a method to calculate mineral modes for such materials samples were prepared using the kbr disc method this ensures that lambert beer s law is valid a quantitative determination of the mineral content from various blends was performed by making a multicomponent analysis of the experimental spectrum using the spectra of each component in the mixture to check the validity of the procedure the multicomponent analysis was performed on spectra from synthetic mixtures of standard minerals quartz kaolinite gibbsite amorphous silica good agreement between actual and computed wt was obtained in the range 1315 315 cm 1 this application of ftir spectroscopy was used to quantify the mineral components of a lacustrine sediment cored at salitre minas gerais brazil the major phases are organic matter kaolinite gibbsite quartz anatase and amorphous silica phytoliths and sponge spicules fifty three samples were analyzed quantitative results from ftir spectroscopy were compared to chemical analyses to assess the validity of the method for the natural sediments phases with no sharp diagnostic spectral features such as anatase or amorphous silica were quantified using the multicomponent analysis the variations of the main mineral phases along the core reflect the mechanisms of transfer from the surrounding soils to the sediment area and the role of the vegetal cover over the drainage area

geochemical tracing and spatial evolution of the sediment bed load of the romaine river quebec canada abstract a four reservoir hydroelectric complex which is projected on the romaine river in eastern quebec canada will likely lead to the complete settling of the sand size bed load of the river in order to characterise the present river bed load sources sediment transport and sedimentary connectivity a study was conducted to document the compositional continuum of the lower 300 km portion of the river bed load samples were collected during the late summer low water period and icp ms geochemical analyses of the light and heavy mineral portions were conducted principal component analysis of the results successfully identified a series of distinctive geochemical domains multivariate euclidean distance coefficients were also calculated between consecutive samples along the river revealing major bed load compositional breaks these results indicate a longitudinal fractionation of the bed load along the 300 km course of the river this is further supported by the sedimentary budget calculated from the annual sedimentary input derived from erosion rates of the river banks from sediment bed load measurements at three gauging stations and from calculated bed load transport capacity at these three locations it appears that significant sediment accommodation space is available on the upper course 250 km of the romaine river in spite of the fact that this river has drained highly sediment laden meltwaters from the receding laurentide ice sheet some 10 ka ago this accommodation space leads to the renewal of the bed load due to recurrent partial to complete sedimentation the major part of the bed load reaching the romaine river mouth originates from the lower 50 km of the river course

inverse estuarine features of the upper gulf of california the upper gulf of california is the shallow depth 30 m tidal area at the head of the gulf of california it is an inverse estuary due to the high evaporation rate e 1 1 m year 1 and almost nil freshwater input from rainfall and the colorado river historical and recent hydrographic data show that the area is almost vertically well mixed throughout the year that the horizontal distribution of properties follows the bathymetry and that the hydrography has a strong annual modulation as in other negative estuaries the year round salinity increase toward the head causes the density to do likewise despite the seasonally reversing temperature gradient the pressure gradient thus formed leads to water mass formation and gravity currents speed 0 1 ms 1 both in winter and in summer in winter the high salinity water sinks beyond 200 m while in summer it only reaches a depth of 20 30 m the gravity currents appear to be modulated by the fortnightly tidal cycle with events in neap tides this phenomenon causes the presence at least during neap tides of slight stratification t 0 2

wind and tidal influence on water circulation in a galician ria nw spain abstract the wind effect on water circulation was described by means of hydrodynamical and thermohaline measurements carried out in the ria of pontevedra nw spain from february to july 1998 the samples were measured both at an anchored station situated in the inner part of the ria and at other stations located in the main channel in this way temporal and spatial events were related thermohaline variables salinity and temperature were used to clarify the current patterns measured at the anchored station it has been observed that there is a clear predominance of wind in the main estuary axis direction the wind direction is strongly dependent on topography wind speeds higher than 4 ms 1 are able to dominate the current at surface layers even against tidal effect easterly winds force water to leave the estuary at surface layers while westerly winds force water to enter it diurnal breezes associated with westerly winds were rarely recorded bottom layers were controlled by tide except during an upwelling event

axial convergence in a well mixed estuary abstract transverse secondary circulations involving surface convergence observed in a well mixed estuary in north wales are made visible by the collection of surface material along an axial line which extends continuously for many kilometres through the estuary the circulation and axial convergence however are seen only during the flood phase of the tide and no similar behaviour has been observed during the ebb phase convergent circulations in the estuary are associated with small but steady transverse density gradients in the cross section produced by non uniform advection of the longitudinal gradient through the channel a diagnostic model using measured mean distributions of cross sectional density indicates surface transverse velocities 0 1 ms 1 similar to those observed in the estuary the model further predicts appreciable transverse divergent currents at a fractional depth of 0 75 a prediction which has been tested in the estuary using a vertical array of accurately resolving current direction indicators

climate and anthropogenic factors influencing an estuarine ecosystem from nw iberia new high resolution multiproxy analyses from san simon bay ria de vigo abstract two sedimentary sequences coastal and subtidal were studied in san simon bay ria de vigo situated on the atlantic coast of nw iberia the coastal record is a shallowing upward sequence which evidences a locally developed low marsh situated below the current beach and dated at the second half of the 4th century during the following decades this low marsh was progressively replaced by an alder swamp which formed on it this suggests an apparent stabilisation or slow down of the relative sea level rsl in this site at the beginning of the dark ages da the subtidal sequence studied reflects the main changes in the landscape the hydrological conditions climate and rsl affecting this part of nw iberia during the last 1250 years evidence of changing dinocysts content in the sediment reveals that two centennial or decadal scale episodes existed of shelf marine waters more intensely penetrating inside the bay between the 15th 18th centuries and at ca 1800 1930 ad besides we related different proxies with the occurrence of four main climatic stages namely the previously described dark ages da ca 350 750 ad the mediaeval climatic anomaly mca ca 750 1100 ad and the little ice age lia ca 1500 1930 ad in addition we propose a regional mca lia transition ca 1100 1500 ad that it has not been previously described our environmental characterization indicates a persistent north atlantic oscillation nao negative mode domain in ria de vigo during the mca but this became weaker during the lia and probably also during the earlier da nao mode become more irregular during the mca lia transition generally persisting in dominant negative mode except for a phase of minor upwelling intensification at ca 1150 1350 ad which mainly affected the external parts of the ria we postulate that an almost simultaneous phase ca 1100 1350 ad of stronger continental contribution in the sediments may be related to increasing storm intensities probably linked to a reinforcement of the easter atlantic ea pattern and also that the intertidal supratidal ecosystems inside san simon bay may have extended further in the past at least towards the end of the 5th century and between ca 1050 1350 ad and ca 1450 1750 ad a number of local historical references are consistent with our palaeoecological data and so support the chronology proposed as well as many of the environmental changes reconstructed this good agreement will help in the interpretation of other analogous sequences extending back in time

wind driven upwelling in the vicinity of cape finisterre spain observations and numerical simulations of upwelling along the galician coast of spain during april 1982 are presented in situ measurements include shipboard determinations of hydrographic and biological parameters from a grid of stations covering the continental shelf from cape finisterre to ria de vigo sea level data from vigo and la coruna and wind stress estimates derived from the ship winds and from surface pressure charts sea surface temperature information and pigment concentration information have been obtained from a sequence of satellite images from the noaa 7 advanced very high resolution radiometer and the nimbus 7 coastal zone color scanner respectively since the cape finisterre sector of the iberian peninsula is characterized by an abrupt change in coastline orientation wind driven upwelling can occur in that region over a 270 range of wind direction these data document the evolution of upwelling and the resultant coastal circulation in response to two wind events that occurred over a 10 day period salient features of the circulation include a southward coastal jet and a northward flow further offshore along the western coast numerical simulations of the coastal currents the vertical excursion of a density interface from a static equilibrium position and coastal sea level are conducted using a wind patch characterized by constant direction and negative curl the simulations show that during these wind events the greatest upwelling will occur either at cape finisterre or along the northern coast as was observed in this case and as has been reported by others it is suggested on the basis of the analysis of the sea level records and on the numerical simulations that wave disturbances propagate northward along the coast at a speed of 120 160 km day finally it is speculated that much of the organic material formed during upwelling events north of the cape finisterre is advected out to sea northwest of the cape

geochemical and geo statistical assessment of heavy metal concentration in the sediments of different coastal ecosystems of andaman islands india spatial distribution of metal concentrations in the surface sediment samples collected from 16 marine locations covering different coastal ecosystems such as mangroves seagrasses dead coral and sandy beaches of the andaman islands india was studied ph ec sediment grain size and heavy metal al cd co cr cu fe mg mn ni pb and zn concentrations were determined and contamination factor cf and geo accumulation index igeo were calculated to understand the pollution status of the study area based on the background values cf of different heavy metals has revealed that different metals have different levels of accumulation viz al 0 01 0 22 mg 0 38 1 85 fe 0 06 0 74 mn 0 04 1 18 cu 0 18 2 93 cr 0 52 12 6 zn 0 3 1 39 ni 0 06 0 89 pb bdl 0 74 co 0 1 0 35 and cd 2 3 12 9 in general the metal concentration was less in these ecosystems when compared to similar ecosystems of mainland of india concentration of some metals like cr and cd was comparatively higher than the background values which is an important issue of concern to the coastal managers of the region spatial data on heavy metals collected now would help the coastal zone managers to identify the vulnerable sites and take remedial actions

wind influence on water exchange between the ria of ferrol nw spain and the shelf abstract the wind induced water exchange between the ria of ferrol nw spain and the adjacent shelf is analyzed by means of a three dimensional hydrodynamic model mohid2000 since thermohaline measurements indicate that the estuary can be considered vertically homogeneous a barotropic version of the model has been used real in situ wind measurements have been used for model calibration and further analysis the approach to study the wind effect on water exchange through the ria strait consisted in subtracting the signal calculated with only tidal forcing t s from the one with wind and tidal forcing wt s this shows the existence of a residual circulation with water flowing in wind direction along surfaces layers and a counter current flowing in the opposite direction at bottom layers the flux across the strait of ferrol has shown to increase linearly on wind strength with a correlation larger than 96 and reaching values close to 20 m 3 s 1 under real wind forcing

an evaporation driven salinity maximum zone in australian tropical estuaries abstract the distribution of temperature and salinity in three tropical australian estuaries was measured in october 1983 in the hot dry season as a result of evaporation a salinity maximum zone exists near the mouth of the river where downwelling occurs and a classical and an inverse internal estuarine circulation prevail respectively upstream and downstream of the salinity maximum zone the zone of salinity maximum can be thought of as a high salinity plug inhibiting so much the mixing of estuarine and ocean waters that in some cases freshwater dose not reach the ocean

an unusual two layered tidal circulation induced by stratification and wind in the ria of pontevedra nw spain abstract a two layered tidal circulation pattern has been observed in the ria of pontevedra at an anchored station 24 m deep located at 42 3917 n and 8 7380 w during a tidal cycle water leaves the estuary continuously through surface layers till 8 12 m depth and enters the estuary through bottom layers this unusual pattern in a partially mixed estuary is observed to depend on the particular summer stratification conditions and on the presence of easterly winds inside the estuary the vertical stratification is generated by solar heating and favourable upwelling conditions on the adjacent shelf which reinforces the estuarine positive circulation and provokes the inflow of typical upwelling water enaw through bottom layers on the other hand the easterly winds inside the estuary are strong enough around 8 m s 1 to force the surface water to move even against tide this situation is compared to two typical patterns observed in the estuary a winter situation where wind drives the surface water against tidal forcing and a spring situation where the water column follows the tidal pattern in both cases bottom layers are hardly influenced by wind forcing

hypersalinity flushing and transient salt wedges in a tidal gulf an inverse estuary abstract because of high evaporation and low rainfall gulfs and embayments in the arid coastal regions of australia are endowed with highly saline water masses with salinities ranging from oceanic values at their mouths to values as high as 60 at their heads this presents the case of an inverse estuary in gulf st vincent of south australia an example of such an inverse estuary the salinity at the head ranges from 39 in winter to 42 in summer in sympathy with the seasonal changes of the local excess of evaporation over precipitation the salient characteristics of temperature salinity and density distributions in the gulf are here described despite a seasonal reversal of spatial temperature gradients the salinity gradient maintains the same sign and is strong enough to control a persistent density gradient from mouth to head in parallel with the case of estuaries a flushing time for salt is defined and estimated for the northern regions of the gulf although the water mass was initially assumed to be vertically well mixed because of tidally induced turbulence the present observations reveal the striking feature that at neap tides the horizontal density gradient forces a salt wedge from the north below the fresher water in the south

vivaldi 1991 a study of the formation circulation and ventilation of eastern north atlantic central water abstract a synoptic hydrographic data set comprising 32 full depth ctd casts and 2500 ctd seasoar profiles to 500 m is used to describe the s properties and circulation of central water east of the mid atlantic ridge and between 39 n and 54 n eastward transport of 20 10 6 m 3 s 1 in the north atlantic current turns entirely northwards to the west of 54 n 20 w this transport consists in the upper layers of western north atlantic water freshened at temperatures below 10 c by mixing with subarctic intermediate water northern and southern branches of the north atlantic current are well defined and both turn northwards west of 20 w a further 10 10 6 m 3 s 1 of eastern north atlantic water forms and recirculates anticyclonically to the west of spain south of the north atlantic current and north of 40 n eastern north atlantic water is most weakly stratified east of 20 w and there is clear correlation between weakly stratified pycnostads and positive salinity anomalies relative to western north atlantic water thus eastern north atlantic water is a winter mode water in which strong winter cooling has increased the density and hence also the salinity anomaly at a given temperature near the southern entrance to the rockall trough there is evidence that salinities are also increased by mediterranean water influence circulation south of the north atlantic current is complex there is no evidence for direct ventilation southwards across 40 n where water properties s potential vorticity and cfc 113 and historical data all indicate westward ventilation east of 24 w with weak southward ventilation occurring further west in the vicinity of the azores the circulation pattern suggested is remarkably similar to that proposed by helland hansen and nansen in 1926 the eastern north atlantic geophysiske publicajoner 4 1 76 with anticyclonic circulation of colder eastern north atlantic water north of 40 n meeting warmer water from south of 40 n circulating cyclonically north of the azores current the distribution of pycnostads and s properties between 20 w and 35 w north of the azores indicates alternate bands of western and eastern north atlantic water moving eastward and westward respectively including evidence for westward motion immediately south of the southern branch of the north atlantic current possibly by westward propagation of anticyclonic eddies containing deep pycnostads

evidence of dynamics reversal in tropical estuaries geomorphological and sedimentological consequences salum and casamance rivers senegal south dakar senegambian estuaries are subject to an unusual hydrodynamical regime caused by weak or absent run off in the salum delta each distributary lacks fresh water during most of the year only the tidal flows arc responsible for geomorphological and sedimentological effects the current distribution shows a net discharge upstream due to the extensive evaporation and evapotranspiration in mangrove swamps and tidal flats consequently the salinity is always higher towards the river than near the sea a high salinity bottom layer suggests the occurrence of a supersaline wedge of reverse sense to the salt wedge of a normal estuary such an inverse pattern is similarly displayed by sedimentological features double upstream tumed spits and by the external location of the turbidity maximum a coherent reverse estuary model is suggested from our field observations

an inshore poleward current in the nw of the iberian peninsula detected from satellite images and its relation withg catenatum and d acuminata blooms in the galician rias abstract toxic gymnodinium catenatum blooms usually occur in the galician rias at the end of the upwelling season which necessitates a ban on harvesting shellfish extraction with subsequent economic losses for this sector one of the possible causes cited in the literature is the advection of populations from outside the area but no evidence was available to substantiate this oceanographic conditions at the end of the upwelling season in the nw coast of the iberian peninsula 39 43 n have been studied for the years 1986 1990 1995 and 1998 sea surface temperature data from satellite images wind data drifter tracks and in situ oceanic data from the galician rias have been combined to clarify the oceanographic structures in the area at the commencement of the blooms on the inner shelf an inshore poleward current advecting warm water has been identified after the cessation of upwelling on the middle and outer shelf a tongue of cold water as a remnant of the previous upwelling continued to move southward on the slope and offshore the poleward counter current reported by several authors was detected carrying warm oceanic water northwards it is suggested that the inshore poleward current not previously reported in the literature could advect initial populations of dinoflagellates to the rias from northern portuguese waters this would explain why blooms such as g catenatum have been found usually in portuguese waters several weeks before the galician rias showing an apparent northward movement but cells of this toxic dinoflagellate species have not been found in waters of the offshore poleward counter current

the werra cyclotheme upper permian fore sudetic monocline poland insights into fluctuations of the sedimentary environment from organic geochemical studies abstract a study of the extracts of samples recording a transgressive regressive succession of the werra cyclothem zechstein upper permian from the southern margin of the european permian basin the fore sudetic monocline poland provides an insight into major sources of organic matter and diagenetic processes the studied cross section comprises all lithologies representative for the european basin including transgressive sandstones weissliegend and organic rich shales kupferschiefer followed by carbonates as well as regressive anhydrites with intercalations of rock salt due to the variable influence of overlapping diagenetic processes that affected the organic matter i e maturation and late diagenetic oxidation related to base metal mineralisation a reliable comparison of the biomarker results is only possible for the major upper part of the section ca 38 m including carbonates and evaporites but not for the oxidised first 2 3 m from the base of the kupferschiefer the transition from carbonate to evaporate sedimentation is associated with a shift to predominant even c numbered n alkanes increased abundance of carotanes and high homohopane index reflecting enhanced reducing conditions the presence of the c25 regular isoprenoid squalane biphytane and the rapid decrease in the pristane phytane ratio in the evaporites are mainly controlled by the important contribution from both halophilic and methanogenic archaea the occurrence of gammacerane in the anhydrites suggests development of water column stratification at some stages of the sea regression this is associated with appearance of specific aryl isoprenoids with a lycopane carbon skeleton most likely related to botrycoccus braunii race l algae lycopane derivative occurrence suggests that such an algal race could have occurred since permian currently known recent eocene the presence of the abundant freshwater brackish algal biomarkers in evaporititic deposits can be envisaged in the costal part of the zechstein basin with temporary salt wedge estuary water stratification the algae bloomed in the top fertile fresh brackish water layer fed by rivers and the algal biomass was deposited on the sea floor covered with evaporitic brine the stratification periodically broke down during precipitation of the rock salt presumably due to a decrease in riverine water input as revealed by characteristic disappearance of gammacerane and hopane distributions similar to those observed for the carbonate rocks the methylphenanthrenes phenanthrene ratio was used together with methyldibenzothiophenes dibenzothiophene ratio to assess maturity these maturity estimations indicate that the peak of oil window has been reached which is confirmed by other biomarker maturity parameters based on sterane and hopane distributions the maturity stage of oil generation and expulsion was further confirmed by the presence of solid bitumen as cements in the sandstone underlying kupferschiefer and bitumen veins and lenses in the carbonates

hydrodynamic model study of the ria de pontevedra under estuarine conditions the ria de pontevedra is one of the galician rias baixas partially mixed estuaries on the north west coast of the iberian peninsula the hydrodynamics of the rias is far from being fully understood in this application the hydrodynamics of the ria de pontevedra is studied by means of a 3 d baroclinic model our aim was to establish the circulation pattern driven by tide and the horizontal density gradient between river and shelf waters under estuarine conditions the spatial variability of tidal velocities and salinities is studied the residual component of the flow related to transport is described and discussed as expected in a partially mixed estuary a double layered residual pattern is observed with water flowing seaward in a surface layer and upstream in a bottom layer a cross channel residual flow not described up to date is presented