Mouth Of Channel Research Articles

Restoration and recovery of hurricane-damaged mangroves using the knickpoint retreat effect and tides as dredging tools

In 2001, a hurricane moved a large sand dune, blocking the sole outlet channel of a mangrove. In the absence of daily tidal flow, the two ponds containing the mangrove vegetation evaporated, the secondary drainage channels were lost, and a salt crust formed on the bed of the ponds. The mangrove lost most of its trees and the remaining suffered from osmotic shock that led to defoliation. Restoration involved creating a knickpoint retreat (waterfall retreat effect) and tidal flow as a dredging mechanism to restore the outlet and form secondary channels in the ponds. During a very low tide, we deepened the mouth of the outlet channel by 1 m below high tide level to form a small waterfall when high tides receded. During successive tides, this one-step knickpoint deteriorated and formed a series of low rapids. With a steep gradient, the rapids retreated upstream into the ponds, first reopening the outlet channel and then carving new secondary channels in the pond mud flat. The excavation process of the outlet channel was repeated three times and was sufficient to effectively improve the hydrology of the entire pond system; allowing adequate flooding and draining of the mangrove ponds. Hydrology analysis tested by the Engelund–Hansen sediment transport formula established that the output of sediment from the ecosystem is greater than the input of sand into the mangroves. This is keeping the main channel continuously open. After eight years, tidal flow continues to keep the channels open; the salt crust has disappeared; the trees have recovered, and a large area of new vegetation has emerged.

Dibenzo[1,2,5]thiadiazepines Are Non-Competitive GABAA Receptor Antagonists

A new process for obtaining dibenzo[c,f][1,2,5]thiadiazepines (DBTDs) and their effects on GABAA receptors of guinea pig myenteric neurons are described. Synthesis of DBTD derivatives began with two commercial aromatic compounds. An azide group was obtained after two sequential reactions, and the central ring was closed via a nitrene to obtain the tricyclic sulfonamides (DBTDs). Whole-cell recordings showed that DBTDs application did not affect the holding current but inhibited the currents induced by GABA (IGABA), which are mediated by GABAA receptors. These DBTDs effects reached their maximum 3 min after application and were: (i) reversible, (ii) concentration-dependent (with a rank order of potency of 2c = 2d > 2b), (iii) mediated by a non-competitive antagonism, and (iv) only observed when applied extracellularly. Picrotoxin (which binds in the channel mouth) and DBTDs effects were not modified when both substances were simultaneous applied. Our results indicate that DBTD acted on the extracellular domain of GABAA channels but independent of the picrotoxin, benzodiazepine, and GABA binding sites. DBTDs used here could be the initial model for synthesizing new GABAA receptor inhibitors with a potential to be used as antidotes for positive modulators of these receptors or to induce experimental epilepsy.

准噶尔盆地中部1、3区块J1s2储层发育特征及有利区带预测<br>The Reservoir Characteristic and Favorable Area Prediction of J1s2 Formation in Block 1 and 3 of Central Junggar Basin

准噶尔盆地具有“盆大、水浅、坡缓、振荡性构造运动”的特征，中部1、3区块侏罗系三工河组是准噶尔盆地腹部重要的勘探目的层系，该组沉积时期主要受北西向与北东向物源共同影响，发育浅湖背景下的三角洲沉积，主要发育三角洲前缘水下分支河道与河口坝砂体，具有较好的储集物性。成藏受控于异常高压带、断裂系统、沉积相带、古隆起等因素，其中，车–莫古隆起的发育和演化为该区创造了独特的油气运聚背景，决定了多期构造演化与多期成藏的特点。 Big area, shallow water, gentle slope and oscillating movement are the main characteristics of the Junggar basin. The J1s2 formation is the main exploration strata of the block 1 and 3. During the J1s2 sedimentary period, on the influence of the northeast and northwest provenance, it developed the delta front deposition under the mere background there. The subaqueous distributary channel and channel mouth bar reservoir have the better physical property. The res- ervoir formation is controlled by the abnormal pressure belt, fracture system, sedimentary facies tract and ancient uplift. Among them, the development and evolution of Chemo ancient uplift supply the peculiar migration and accumulation background for oil & gas, which determined the characteristics of polyphase structural evolution and reservoir formation.

Alluvial transport processes and the impact of Anthropogenic intervention on the Romanian littoral of the Danube Delta

Within the context of shoreline alteration, the impact of hydrotechnical works on coastal processes has been increasingly discussed in the literature. In this study, we analysed the Romanian deltaic littoral, which is situated between the mouths of the Chilia arm (North) and Midia Cape (South) of the Danube Delta, with a total length of 166 km. The present study examines the hydrotechnical works constructed at the mouth of the Sulina arm and the inlet of Portita. In 1858, the European Danube Commission (which was created in 1856 but whose projects were initiated previously to that date) built the first hydrotechnical works at the mouths of the Danube. The maritime sector between the two river mouths (the Sulina and the St. Gheorghe) is 33 km long and is impacted by maritime forces that run both parallel and perpendicular to the mouths of the river. The continuous advancement of dams, which currently reach lengths of 9 km, has altered the shore. As the dams advance towards the sea, the north–south current is forced to deviate from its original route. The northern current, which is at its maximum extent during the winter months, is eroding the areas located next to the Imputita brook (north) and the Sondei channel (south). These areas of the shore are also influenced by the southern current, which moves in a south–north direction and is at its maximum during the summer season when it pushes the northern current towards the “alluvial trap”. Therefore, the maximum erosion occurs next to the Imputita brook (north). In the “alluvial trap” located south of the advancing dams, the particle size of the sandy deposits is slightly different from that of deposits in the erosive sector of the Imputita-Sondei. The jetties curve south, which causes a slight decrease in the rate of the “Sulina bar” formation because the waves coming from offshore do not directly enter the channel mouth, and thus the deposition of alluvium is slowed. Lateral erosion is visibly increased between the two river mouths due to a decreasing alluvial budget. Intense erosive processes also affect the Razim-Sinoie coastal barrier, which closes the lagoon of the same name. The first major hydrotechnical alterations were erected in the 1970s (when channels connecting to the St. Gheorghe mouth were first dug, and contact with the sea was totally or partially interrupted), and the inlets and outlets of the lagoon complex are now human-controlled. The hydrotechnical works led to an alteration in the direction and force of the littoral currents as well as a decrease in the amount of alluvia, thus altering the sedimentary budget. Over 60% of the entire deltaic littoral is currently eroding and the other 40% is accumulating.

Salt Fluxes in a Complex River Mouth System of Portugal

Measurements of velocity and salinity near the mouth and head of the Espinheiro channel (Ria de Aveiro lagoon, Portugal) are used to study the local variation of physical water properties and to assess the balance, under steady conditions, between the seaward salt transport induced by river discharge and the landward dispersion induced by various mixing mechanisms. This assessment is made using data sampled during complete tidal cycles. Under the assumption that the estuarine tidal channel is laterally homogeneous and during moderate tidal periods (except for one survey), currents and salinity data were decomposed into various spatial and temporal means and their deviations. Near the channel's mouth, the main contributions to the salt transport are the terms due to freshwater discharge and the tidal correlation. Near the channel's head, this last term is less important than the density driven circulation, which is enhanced by the increase in freshwater discharge. The remaining terms, which are dependent on the deviations from the mean depth have a smaller role in the results of salt transport. The computed salt transport per unit width of a section perpendicular to the mean flow is in close agreement to the sum of the advective and dispersive terms (within or very close to 12%). An imbalance of the salt budget across the sections is observed for all the surveys. Considerations are made on how this approach can inform the management of hazardous contamination and how to use these results to best time the release of environmental flows during dry months.

Channel-related sediment waves on the eastern slope offshore Dongsha Islands, northern South China Sea

The characteristics and origin of the sediment waves on the eastern slope offshore Dongsha Islands, northern South China Sea (SCS) were analyzed by integrating high-resolution multibeam bathymetric, seismic and piston core data. Four sediment wave fields were identified, which are the West Dongsha Channel (WDSW), West Taiwan Channel (WTSW), South Taiwan Channel (STSW) and West Penghu Channel (WPSW) sediment wave fields, respectively. They are distributed on the right levees (looking downstream) and adjacent overbank areas of related channels (WDSW, WTSW, and STSW), or developed outside the channel mouths (WPSW). Each sediment wave field consists of several to tens of rows of sediment waves. These sediment waves are up to 2.8–7.2km in wavelength and 30–60m in wave height. With wave crests orthogonal to or oblique to the orientation of the channels, the sediment waves gradually decrease in dimension both in downslope direction and with the distance increasing away from the channel. Most sediment waves are asymmetric in cross sections with a thicker upslope flank and a thinner downslope flank, and therefore migrate upslope. Piston cores suggest that sandy turbidites developed with normal size grading dominate the channels, while massive muds with thin sandy or silty turbidite interbeds prevail in the inter-channel regions on which the sediment waves situated. The sediment waves on the channel levees and related overbank areas (WDSW, WTSW, and STWD) were presumably built by the turbidity currents overspilled from the channels; while those in WPSW, located outside the mouth of the West Penghu Channel, are suggested generated by unconfined sheet-like turbidity currents outside the channel mouth.

Characterization of a novel somatic KCNJ5 mutation delI157 in an aldosterone-producing adenoma

Adrenal aldosterone-producing adenomas (APAs) are an increasingly recognized cause of primary aldosteronism, and somatic mutations within the KCNJ5 gene encoding an inwardly rectifying K(+) channel (also called GIRK4 or Kir3.4) have been identified by several groups including our own. We identified the previously noted G151R and L168R mutations in the region of a selectivity filter of the channel as well as a previously unreported 3-base deletion, delI157. Here, we report the functional properties of KCNJ5 channels carrying this novel delI157 mutation. The delI157 mutation was introduced into wild-type KCNJ5 sequences to allow its expression in both H295R cells and Xenopus oocytes to study its expression and electrophysiology, respectively. In the adrenal cell line H295R, the delI157 mutant expresses and traffics normally to the cell surface. However, the current-voltage behavior of the mutant in oocytes is distinct from wild-type channels and mimics closely other selectivity filter mutations. In particular, its ability to support substantial current when extracellular K(+) is replaced by Na(+). We also report for the first time that the mutants have reduced sensitivity to the KCNJ5 inhibitor tertiapin-Q that binds to the external vestibule of the channel pore. This novel KCNJ5 mutation behaves like the three selectivity filter mutations previously reported in APAs depolarizing the cell and showing reduced cation selectivity. The reduced sensitivity to tertiapin-Q suggests that the abnormal Na(+) permeability of these selectivity mutations does indeed reflect structural changes around the mouth of the ion channel.

Sediment regime and morphological processes in the Hong Ha (Red River) mouth area

Main features of sediment regime in the mouth area of the Hong Ha River (Red River), Vietnam, are discussed. As shown, the hydraulic engineering construction on the Da tributary resulted in a nearly two-fold decrease of river sediment yield. Sediment budget components at the river mouth were analyzed to establish that more than 90% of the sediment yield was detained in the delta branches and in the nearshore zone of the river mouth. Morphological processes in the Hong Ha River mouth area were characterized in detail including delta evolution during Holocene and the dynamics of its channel network, coastline, and mouth bars. Special attention was given to modern processes of delta progradation at the mouths of main branches and to wave erosion of other parts of the delta coastline. The causes for the intensification of this kind of erosion and change of the delta type in the late XX century are discussed.

150 years of anthropogenic metal input in a Biosphere Reserve: the case study of the Cananéia–Iguape coastal system, Southeastern Brazil

The Cananeia–Iguape system consists of a complex of estuarine and lagoonal channels located in the coastal region of southeastern Brazil known as Lagamar, a Biosphere Reserve recognized by the United Nations Educational, Scientific and Cultural Organization (UNESCO) in 1991. The area suffered dramatic environmental changes along the last ca. 150 years initiated by the 1852 opening of an artificial channel, the Valo Grande, connecting the Ribeira de Iguape River to the estuarine system. Due to Au, Ag, Zn, and Pb mining activities that took place in the upstream regions of the Ribeira de Iguape River since the seventeenth century, the system has acted as a final destination of contaminated sediments. Analysis of cores located along the estuarine system revealed a history of contamination, with an increase of anthropogenic metal input between the decades of 1930 and 1990. The anthropogenic influence can be traced in locations as far as 20 km from the mouth of the artificial channel.

Detection of Viruses in Coastal Seawater Using Mytilus Galloprovincialis as an Accumulation Matrix

The purpose of this study was to demonstrate that shellfish can be used to detect enteric viruses in marine waters where they are present at very low concentrations. Aqua-cultured mussels were placed in the sea just off the mouth of a drainage channel affected by human and animal faecal contamination. Samples were taken from the channel, the sea and the mussels at intervals over two 4-week periods. The samples were tested to verify the presence of both rotaviruses and E. coli. Rotaviruses were detected by Real Time-PCR, typed by multiplex PCR and subsequently sequenced. E. coli was enumerated in water matrices by a filtering method and in mussels by the MPN method. The presence of E. coli in the examined matrices demonstrates contamination of faecal origin throughout the studied environments. Rotaviruses were recorded in channel waters, but not in sea water. In both experiments, rotaviruses were detected in mussels 21 and 28 days after being placed in the sea water off the channel mouth. The use of mussels thus enabled the detection of rotaviruses in waters where the high dilution rendered direct investigation impossible. This study indicates that mussels can be used in marine virological surveillance programs.

The Mechanism of PEO Process on Al–Si Alloys in Zirconate Solution

Zirconia coating was produced on Al-Si alloys by plasma electrolytic oxidation (PEO). The alkaline electrolyte containing Zr(OH)4 powders was used. The composition and structure of the coating were investigated by SEM and XRD. The results show that in the initial stages of oxidation the growth of coating belongs to the stage of anodic oxidation controlled by electrochemical polarization. The growth of coating is mainly outward growth and the growth rate is faster. With elongated treated time and increased thickness of the coating, the growth of coating is mainly ingrowth. In contrast with the stage of anodization, the growth rate of plasma electrolytic oxidation is slower than anodization. The coating consists of t-ZrO2, m-ZrO2, α-Al2O3 and γ-Al2O3.T-ZrO2 is the main phase and distributes in outer layer of the coating, however, α-Al2O3 appears in inner layer of the coating. Many micro-particles appear on the coating surface with dimension of 1-2μm.. In the process of plasma electrolytic oxidation, Zr(OH)4 powders move and deposit on the mouth of plasma discharge channel under the effect of electric field force, then it is transformed to ZrO2 by the high temperature of plasma discharge.

Ion selectivity and current saturation in inward-rectifier K+ channels

We investigated the features of the inward-rectifier K channel Kir1.1 (ROMK) that underlie the saturation of currents through these channels as a function of permeant ion concentration. We compared values of maximal currents and apparent Km for three permeant ions: K+, Rb+, and NH4+. Compared with K+ (imax = 4.6 pA and Km = 10 mM at −100 mV), Rb+ had a lower permeability, a lower imax (1.8 pA), and a higher Km (26 mM). For NH4+, the permeability was reduced more with smaller changes in imax (3.7 pA) and Km (16 mM). We assessed the role of a site near the outer mouth of channel in the saturation process. This site could be occupied by either permeant ions or low-affinity blocking ions such as Na+, Li+, Mg2+, and Ca2+ with similar voltage dependence (apparent valence, 0.15–0.20). It prefers Mg2+ over Ca2+ and has a monovalent cation selectivity, based on the ability to displace Mg2+, of K+ > Li+ ∼ Na+ > Rb+ ∼ NH4+. Conversely, in the presence of Mg2+, the Km for K+ conductance was substantially increased. The ability of Mg2+ to block the channels was reduced when four negatively charged amino acids in the extracellular domain of the channel were mutated to neutral residues. The apparent Km for K+ conduction was unchanged by these mutations under control conditions but became sensitive to the presence of external negative charges when residual divalent cations were chelated with EDTA. The results suggest that a binding site in the outer mouth of the pore controls current saturation. Permeability is more affected by interactions with other sites within the selectivity filter. Most features of permeation (and block) could be simulated by a five-state kinetic model of ion movement through the channel.

Composition and source apportionment of PAHs in sediments at river mouths and channel in Kaohsiung Harbor, Taiwan

Fifty-eight sediment samples were collected in 2009 from the bottom of river mouths near Kaohsiung Harbor (Taiwan) and the harbor channel for the analyses of polycyclic aromatic hydrocarbons (PAHs) using gas chromatography-mass spectrometry (GC-MS). Concentrations of total PAHs varied from 39 to 30,521 ng g(-1) (dry weight); samples collected from the mouths of Love River, Canon River, Jen-Gen River, and Salt River showed the highest PAHs concentrations. This indicates that the major sources of sediment PAHs come from those polluted urban rivers and the harbor channel. In samples collected from the Salt River mouth, approximately 43% of the PAHs are identified as PAHs with 2 or 3 rings. However, samples collected from other locations contain predominantly PAHs with 4 rings (32 to 42%) or 5 and 6 rings (36 to 44%). Emissions from traffic-related sources and waste incineration contribute to the majority of PAHs found in most channel and river mouth sediments. However, coal/oil combustion is the main cause of high concentrations of PAHs observed in the Salt River mouth sediments. Principal component analyses with multivariate linear regression (PCA/MLR) have been used to further quantify the source contributions, and the results show that the contributions of coal/oil combustion, traffic-related and waste incineration are 37%, 33% and 30%, respectively.

Structural Basis of the Anti-inflammatory Activity of Melatonin

The anti-inflammatory activity of melatonin (CAS 73-31-4) was examined, using the rat paw edema model, and compared with the non-steroidal anti-inflammatory drug (NSAID) indometacin (CAS 53-86-1) which exerts its effects by inhibition of prostaglandin production on acute inflammation. The experiments showed that melatonin has an important effect on acute inflammatory processes acting as an inhibitor in a similar manner to indometacin. The structural interactions of melatonin with cyclooxygenase (COX), the pharmacological target of NSAIDs, were investigated using computer graphics applications. The results indicated that melatonin has an excellent steric and electronic complementarity with COX. It was found, similarly to previously studied crystal structures of protein-inhibitor complexes, that almost all interactions were of the hydrophobic type but for the typical carboxylate or electronegative group interaction, at the mouth of the active site channel, with Arg 120 and Tyr 355. Therefore, it seems possible that melatonin might bind to the active site of COX-1 and COX-2 suggesting that it may act as a natural inhibitor of the functions of cyclooxygenase modulating in a natural manner the activity of this enzyme.

Overview of the second stage in the comprehensive mirrors test in JET

The first mirror test for ITER in JET with carbon walls has been completed. Thirty polycrystalline Mo mirrors including four coated with a 1 μm rhodium (Rh) film were exposed to plasma in the divertor region and in the main chamber. The mirrors were installed in eight cassettes of pan-pipe shape. The reflectivity of all mirrors exposed in the divertor has been degraded by 80–90% because of the formation of thick (>20 μm) flaking co-deposits on surfaces. Only small reflectivity losses (5–10%) occurred on mirrors located at the channel mouth of the cassettes from the main chamber wall. This is due to the in situ removal of deposited species by charge exchange neutrals. Deuterium, 12C and 9Be are the main isotopes detected on surfaces, but other isotopes (13C) are also found in some locations, thus indicating differences in the material migration. Rhodium coatings with an initial reflectivity that is 30% better than that of pure Mo survived the test without detachment, but their resultant reflectivity was the same as that of the exposed Mo surfaces.

Activity of 3-Ketosteroid 9α-Hydroxylase (KshAB) Indicates Cholesterol Side Chain and Ring Degradation Occur Simultaneously in Mycobacterium tuberculosis

Mycobacterium tuberculosis (Mtb), a significant global pathogen, contains a cholesterol catabolic pathway. Although the precise role of cholesterol catabolism in Mtb remains unclear, the Rieske monooxygenase in this pathway, 3-ketosteroid 9α-hydroxylase (KshAB), has been identified as a virulence factor. To investigate the physiological substrate of KshAB, a rhodococcal acyl-CoA synthetase was used to produce the coenzyme A thioesters of two cholesterol derivatives: 3-oxo-23,24-bisnorchol-4-en-22-oic acid (forming 4-BNC-CoA) and 3-oxo-23,24-bisnorchola-1,4-dien-22-oic acid (forming 1,4-BNC-CoA). The apparent specificity constant (k(cat)/K(m)) of KshAB for the CoA thioester substrates was 20-30 times that for the corresponding 17-keto compounds previously proposed as physiological substrates. The apparent K(m)(O(2)) was 90 ± 10 μM in the presence of 1,4-BNC-CoA, consistent with the value for two other cholesterol catabolic oxygenases. The Δ(1) ketosteroid dehydrogenase KstD acted with KshAB to cleave steroid ring B with a specific activity eight times greater for a CoA thioester than the corresponding ketone. Finally, modeling 1,4-BNC-CoA into the KshA crystal structure suggested that the CoA moiety binds in a pocket at the mouth of the active site channel and could contribute to substrate specificity. These results indicate that the physiological substrates of KshAB are CoA thioester intermediates of cholesterol side chain degradation and that side chain and ring degradation occur concurrently in Mtb. This finding has implications for steroid metabolites potentially released by the pathogen during infection and for the design of inhibitors for cholesterol-degrading enzymes. The methodologies and rhodococcal enzymes used to generate thioesters will facilitate the further study of cholesterol catabolism.

The Structural Basis for Substrate Recognition by Mammalian Polynucleotide Kinase 3′ Phosphatase

Mammalian polynucleotide kinase 3' phosphatase (PNK) plays a key role in the repair of DNA damage, functioning as part of both the nonhomologous end-joining (NHEJ) and base excision repair (BER) pathways. Through its two catalytic activities, PNK ensures that DNA termini are compatible with extension and ligation by either removing 3'-phosphates from, or by phosphorylating 5'-hydroxyl groups on, the ribose sugar of the DNA backbone. We have now determined crystal structures of murine PNK with DNA molecules bound to both of its active sites. The structure of ssDNA engaged with the 3'-phosphatase domain suggests a mechanism of substrate interaction that assists DNA end seeking. The structure of dsDNA bound to the 5'-kinase domain reveals a mechanism of DNA bending that facilitates recognition of DNA ends in the context of single-strand and double-strand breaks and suggests a close functional cooperation in substrate recognition between the kinase and phosphatase active sites.

Study of the surface water circulation in San Blas channel (Argentina) using landsat imagery

This paper deals with the application of satellite images to study turbidity and water circulation patterns in San Blas channel during a theoretical tidal cycle. Eight Landsat TM and ETM images acquired under clear-sky conditions and representing different tidal stages were selected from a pool of Landsat images provided by the argentinean National Commission of Space Activities (CONAE) and the US Geological Survey. Standard digital image processing techniques were used to perform geometric and radiometric corrections on the visible and near-infrared bands. An image-based atmospheric correction (COST method by CHAVEZ, 1996) was applied. An ISODATA unsupervised classification was performed in order to identify different turbidity levels throughout the channel and adjacent areas. The results suggest that suspended sediment transport towards the channel mouth by ebb currents occurs along both flanks. These currents carry suspended sediment into the open sea, generating an ebb tidal delta which tends to rotate in a clockwise direction. Flood currents trigger turbidity mostly over the southern flank of the channel, generating a flood tidal delta with elongated banks extending in the direction of the tidal currents. From the elongated shape of the turbidity plumes, general tidal circulation patterns were identified.

Timothy Mutation Disrupts the Link between Activation and Inactivation in CaV1.2 Protein

The Timothy syndrome mutations G402S and G406R abolish inactivation of CaV1.2 and cause multiorgan dysfunction and lethal arrhythmias. To gain insights into the consequences of the G402S mutation on structure and function of the channel, we systematically mutated the corresponding Gly-432 of the rabbit channel and applied homology modeling. All mutations of Gly-432 (G432A/M/N/V/W) diminished channel inactivation. Homology modeling revealed that Gly-432 forms part of a highly conserved structure motif (G/A/G/A) of small residues in homologous positions of all four domains (Gly-432 (IS6), Ala-780 (IIS6), Gly-1193 (IIIS6), Ala-1503 (IVS6)). Corresponding mutations in domains II, III, and IV induced, in contrast, parallel shifts of activation and inactivation curves indicating a preserved coupling between both processes. Disruption between coupling of activation and inactivation was specific for mutations of Gly-432 in domain I. Mutations of Gly-432 removed inactivation irrespective of the changes in activation. In all four domains residues G/A/G/A are in close contact with larger bulky amino acids from neighboring S6 helices. These interactions apparently provide adhesion points, thereby tightly sealing the activation gate of CaV1.2 in the closed state. Such a structural hypothesis is supported by changes in activation gating induced by mutations of the G/A/G/A residues. The structural implications for CaV1.2 activation and inactivation gating are discussed.

Potencial de transporte sedimentar pelas correntes de fundo na região do Canal de Vema (Atlântico Sul)

Vema Channel is an important passageway to the flow of bottom water between the Argentine and the Brazil basins. The channel morphology causes confinement and intensification of bottom currents that affect the ocean floor through sediment resuspension, transport and deposition, consequently playing a fundamental role in the formation of deep ocean deposits. The main goal of this paper is to evaluate the potential for sediment suspension and transport by the local currents through estimates of nearbed shear stresses as well as to assess whether the present dynamic conditions are conducive to the buildup of contouritic deposits in the Vema channel area. The available datasets include (i) current velocity and direction from the World Ocean Circulation Experiment (WOCE) and from moorings deployed by the Woods Hole Oceanographic Institute (WHOI); (ii) hydrographic parameters from the World Ocean Database 2005; and (iii) the description of bottom sediment characteristics and nephelometric profiles available in publications such as research reports and scientific articles. Calculated shear stresses indicate that local currents would be able to erode and transport medium silt with density similar to that of quartz during up to 87% of the deployment duration, a finding that is reinforced by the nephelometric profiles and by suspended particulate matter concentrations documented by filtered water samples. Channel enlargement downstream leads to loss of transport capacity along the channel. These results suggest that a modern drift deposit may still be under construction downstream the channel mouth wherea contourite fan has intermittently been built since the late Oligocene.