scholarly journals Global spatial distribution of natural riverine silica inputs to the coastal zone

2011 ◽  
Vol 8 (3) ◽  
pp. 597-620 ◽  
Author(s):  
H. H. Dürr ◽  
M. Meybeck ◽  
J. Hartmann ◽  
G. G. Laruelle ◽  
V. Roubeix
Keyword(s):  
Spatial Distribution ◽  
Coastal Zone ◽  
Major Product ◽  
Tectonic Activity ◽  
Drainage Basins ◽  
Global Average ◽  
Marginal Seas ◽  
Order Of Magnitude ◽  
Essential Nutrient ◽  
Particulate Silica

Abstract. Silica, SiO2, in dissolved (DSi) and particulate (PSi) form, is both a major product of continental weathering as well as an essential nutrient in terrestrial and aquatic systems. Here we present estimates of the spatial distribution of riverine silica fluxes under natural conditions, i.e. without human influence, to ~140 segments of the global coastal zone. Focussing on the construction of the DSi budget, natural DSi concentration is multiplied with discharge of rivers for each segment for documented basins and segments. Segments with no documentation available are estimated using clustered information based mainly on considerations of local lithology, climate, and lake retention. We approximate fluxes of particulate silica in various forms (PSi) from fluxes of suspended matter, calculated from existing models. Results have been established for silica fluxes, concentrations and yields for drainage basins of the different continents, oceans basins as well as coastal segment basins. For the continental surfaces actually draining into the oceans (exorheic regions, representing 114.7 million (M) km2), 371 M t y−1 of DSi and 8835 M t y−1 of PSi are transported, corresponding to a mean concentration of 9.5 mg l−1 and 226 mg l−1, and to a mean yield of 3.3 t km−2 y−1 and 77 t km−2 y−1, respectively. DSi yields exceeding 6.6 t km−2 y−1, i.e. >2× the global average, represent 17.4% of the global continental ice-free exorheic area but correspond to 56.0% of DSi fluxes. Pacific catchments hold most of the hyper-active areas (>5× global average), suggesting a close connection between tectonic activity and DSi fluxes resulting from silicate weathering. The macro-filters of regional and marginal seas intercept 33% and 46% of the total dissolved and particulate silica fluxes. The mass of DSi received from rivers per unit square area of various oceans ranges over more than one order of magnitude. When expressed per unit volume and when individual regional seas are considered this figure ranges over two to three orders of magnitude, an illustration of the heterogeneity of the land to sea connection.

scholarly journals Global spatial distribution of natural riverine silica inputs to the coastal zone

2009 ◽  
Vol 6 (1) ◽  
pp. 1345-1401 ◽  
Author(s):  
H. H. Dürr ◽  
M. Meybeck ◽  
J. Hartmann ◽  
G. G. Laruelle ◽  
V. Roubeix
Keyword(s):  
Spatial Distribution ◽  
Coastal Zone ◽  
Major Product ◽  
Tectonic Activity ◽  
Drainage Basins ◽  
Global Average ◽  
Marginal Seas ◽  
Essential Nutrient ◽  
Mean Concentration ◽  
Particulate Silica

Abstract. Silica, SiO2, in dissolved (DSi) and particulate (PSi) form, is both a major product of continental weathering as well as an essential nutrient in terrestrial and aquatic systems. Here we present estimates of the spatial distribution of riverine silica fluxes under natural conditions, i.e. without human influence, to ~140 segments of the global coastal zone. Focussing on the construction of the DSi budget, natural DSi concentration is multiplied with discharge of rivers for each segment for documented basins and segments. Segments with no documentation available are estimated using clustered information based mainly on considerations of local lithology, climate, and lake retention. We approximate fluxes of particulate silica in various forms (PSi) from fluxes of suspended matter, calculated from existing models. Results have been established for silica fluxes, concentrations and yields for drainage basins of the different continents, oceans basins as well as coastal segment basins. For the continental surfaces actually draining into the oceans (exorheic regions, representing 114.7 M km2), 371 M t y−1 of DSi and 8835 M t y−1 of PSi are transported, corresponding to a mean concentration of 9.5 mg l−1 and 226 mg l−1, and to a mean yield of 3.3 t km−2 y−1 and 77 t km−2 y−1, respectively. DSi yields exceeding 6.6 t km−2 y−1, i.e. >2× the global average, represent 17.4% of the global continental ice-free exorheic area but correspond to 56.0% of DSi fluxes. Pacific catchments hold most of the hyper-active areas (>5× global average), suggesting a close connection between tectonic activity and DSi fluxes resulting from silicate weathering. The macro-filters of regional and marginal seas intercept 33% and 46% of the total dissolved and particulate silica fluxes.

scholarly journals Μorphometric Analysis for the Assessment of Relative Tectonic Activity in Evia Island, Greece

Geosciences ◽  
2020 ◽  
Vol 10 (7) ◽  
pp. 264
Author(s):  
Kanella Valkanou ◽  
Efthimios Karymbalis ◽  
Dimitris Papanastassiou ◽  
Mauro Soldati ◽  
Christos Chalkias ◽  
...  
Keyword(s):  
Spatial Distribution ◽  
Fault Zone ◽  
Normal Fault ◽  
Morphometric Parameters ◽  
Tectonic Activity ◽  
Asymmetry Factor ◽  
Drainage Basins ◽  
Fault Systems ◽  
The North ◽  
Integrated Index

The aim of this study is to evaluate the relative tectonic activity in the north part of the Evia Island, located in Central Greece, and to investigate the contribution of neotectonic processes in the development of the fluvial landscape. Five morphometric parameters, including Drainage Basin Slope (Sb), Hypsometric Integral (Hi), Asymmetry Factor (Af), Relief Ratio (Rh), and Melton’s Ruggedness Number (M), were estimated for a total of 189 drainage basins. The catchments were classified into two groups, according to the estimated values of each morphometric parameter, and maps showing their spatial distribution were produced. The combination of the calculated morphometric parameters led to a new single integrated Index of relative tectonic activity (named Irta). Following this indexing, the basins were characterized as of low, moderate, or high relative tectonic activity. The quantitative analysis showed that the development of the present drainage systems and the geometry of the basins of the study area have been influenced by the tectonic uplift caused by the activity of two NW-SE trending offshore active normal fault systems: the north Gulf of Evia fault zone (Kandili-Telethrion) and the Aegean Sea fault zone (Dirfis), respectively. The spatial distribution of the values of the new integrated index Irta showed significant differences among the drainage basins that reflect differences in relative tectonic activity related to their location with regard to the normal fault systems of the study area.

scholarly journals Mapping gaseous amines, ammonia, and their particulate counterparts in marine atmospheres of China’s marginal seas: Part 1 – Differentiating marine emission from continental transport

2021 ◽  
Author(s):  
Dihui Chen ◽  
Yanjie Shen ◽  
Juntao Wang ◽  
Yang Gao ◽  
Huiwang Gao ◽  
...  
Keyword(s):  
Significant Negative Correlation ◽  
The Yellow Sea ◽  
Sea Spray ◽  
Marine Atmosphere ◽  
Coastal Site ◽  
Marginal Seas ◽  
Range Transport ◽  
Order Of Magnitude ◽  
Using Data ◽  
Set Up

Abstract. To study sea-derived gaseous amines, ammonia, and primary particulate aminium ions in the marine atmospheres of China's marginal seas, an onboard URG-9000D Ambient Ion Monitor-Ion chromatography (AIM-IC, Thermo Fisher) was set up on the front deck of the R/V Dongfanghong 3 to semi-continuously measure the spatiotemporal variations in the concentrations of atmospheric trimethylamine (TMAgas), dimethylamine (DMAgas), and ammonia (NH3gas) along with their particulate matter (PM2.5) counterparts. In this study, we differentiated marine emissions of the gas species originating from continental transport using data obtained from December 9 to 22, 2019 during the cruise over the Yellow and Bohai Seas, facilitated by additional measurements collected at a coastal site near the Yellow Sea during summer 2019. The data obtained during the cruise and the coastal site demonstrated that the observed TMAgas and protonated trimethylamine (TMAH+) in PM2.5 over the Yellow and Bohai Seas overwhelmingly originated from marine sources. During the cruise, there was no significant correlation (P > 0.05) between the simultaneously measured TMAH+ and TMAgas concentrations. Additionally, the concentrations of TMAH+ in the marine atmosphere varied around 0.28 ± 0.18 μg m−3 (average  ±  standard deviation), with several episodic hourly average values exceeding 1 μg m−3, which were approximately one order of magnitude larger than those of TMAgas (approximately 0.031 ± 0.009 μg m−3). Moreover, there was a significant negative correlation (P < 0.01) between the concentrations of TMAH+ and NH4+ in PM2.5 during the cruise. Therefore, the observed TMAH+ in PM2.5 was overwhelmingly derived from primary sea-spray aerosols. Using the TMAgas and TMAH+ in PM2.5 as tracers for sea-derived basic gases and sea-spray particulate aminium ions, the values of non-sea-derived DMAgas and NH3gas, as well as non-sea-spray particulate DMAH+ in PM2.5, were estimated, and the estimated average values of each species contributed to 16 %, 34 %, and 65 % of the observed average concentrations, respectively. Uncertainties remained in the estimations as TMAH+ may decompose into smaller molecules in seawater to varying extents. The non-sea-derived gases and non-sea-spray particulate DMAH+ likely originated from long-range transport from the upwind continents, according to the recorded offshore winds and increased concentrations of SO42− and NH4+ in PM2.5. The lack of a detectable increase in the particulate DMAH+, NH4+, and SO42− concentrations in several SO2 plumes did not support the secondary formation of particulate DMAH+ in the marine atmosphere.

Extragalactic X-ray sources and the diffuse X-ray background

1979 ◽  
Vol 366 (1726) ◽  
pp. 391-402 ◽  
Keyword(s):  
Spatial Distribution ◽  
Euclidean Space ◽  
Active Galaxies ◽  
Clusters Of Galaxies ◽  
Optical Identification ◽  
X Ray ◽  
Luminosity Functions ◽  
Sky Survey ◽  
Order Of Magnitude ◽  
X Ray Background

Results from the Ariel 5 sky survey instrument relating to the properties and the spatial distribution of extragalactic X-ray sources are discussed. The lg N -lg S relation for sources in the 2A catalogue is consistent with a uniform distribution of sources in Euclidean space. In addition, measure­ments of fluctuations in the X-ray background suggest that the Euclidean form of the source counts can be extrapolated to flux levels at least an order of magnitude fainter than the 2A catalogue limit. Information is also available from the optical identification of 2A sources which, through redshift measurements, enables the X-ray luminosity functions of the two main classes of source, namely clusters of galaxies and active galaxies, to be determined. The luminosity functions can be used to calculate the contribution of clusters of galaxies and active galaxies to the diffuse X-ray background in the 2-10 keV range. It is found that cosmological evolution of one or both populations is required to account for the diffuse X-ray background entirely in terms of the integrated emission from these sources.

scholarly journals Evaluation of the drainage system of Zagros Basin (Greater Zab River, northern Iraq) and insights into tectonic geomorphology

2020 ◽  
Vol 13 (22) ◽  
Author(s):  
Ziyad Elias ◽  
Varoujan K. Sissakian ◽  
Nadhir Al-Ansari
Keyword(s):  
Drainage System ◽  
Tectonic Activity ◽  
Mature Stage ◽  
Tectonic Geomorphology ◽  
Drainage Basins ◽  
Main Trunk ◽  
Northern Iraq ◽  
Clastic Rocks ◽  
North Iraq ◽  
Anomaly Index

AbstractGeomorphological evaluation was carried out for three drainage basins named Hareer, Dwaine, and Hijran, which are tributaries of the Greater Zab River in the northern part of Erbil Governorate, the Iraqi Kurdistan Region, north Iraq. The exposed rocks in the three basins are mainly clastic rocks (sandstone, claystone, and conglomerate, with subordinate gypsum and limestone beds). However, in the uppermost parts of the basins, thick and massive carbonate rocks are exposed. Tectonically, the three basins are located in the Low Folded and High Folded Zones, which belong to the Zagros Fold–Thrust Belt. The main aim of the current study is to deduce the tectonic activity of the area occupied by the studied three basins. We have used and interpreted Radar Topography Mission (SRTM) data to perform the geomorphological evaluation. Different geomorphological indices and forms were used to deduce the tectonic activity of the area occupied by the three basins. Accordingly, seven orders of streams were identified in the three basins. The number of the streams with low order (i.e., 1) joining with higher order (i.e., 6 and 7) is considerably higher in the three basins. The Hat values of the three basins are 12,971, 10,479, and 7014 in Hareer, Dwaine, and Hijran basins, respectively. The values of hierarchical anomaly index (Δa) of the three basins are 1.87, 1.35, and 2.37 in Hareer, Hijran, and Dwaine basins, respectively. It was observed that the shape of Hareer and Shakrook anticlines has a significant impact on the main trunk of the channel. Therefore, when an anticline and syncline are close to each other (due to thrust faulting), then the hierarchical anomaly increases because the river trunk receives a lot of first-order streams, e.g., in Dwaine and Hijran basins. The lateral growth in the eastern part of Safin anticline had caused increasing of the Δa. The increased hierarchical anomaly index is attributed to the existence of faults and lineaments, which represent weakness zones. The hypsometric curves of the three basins have a typical shape of old stage with rejuvenation in their central and terminal portions which is changed into mature stage, most probably due to the local uplift which is caused by normal, thrust, and strike–slip (oblique) faults which exist in the study area and the near surroundings. The Bs and Hat values in Hareer, Dwaine, and Hijran basins indicate that the basins exhibit low, medium, and high tectonic activity, respectively.

scholarly journals mm-VLBI observations of SiO masers: Further support for radiative pumping and rotation of the inner shell

2002 ◽  
Vol 206 ◽  
pp. 286-289
Author(s):  
Jean-François Desmurs ◽  
Valentín Bujarrabal ◽  
Francisco Colomer ◽  
Javier Alcolea
Keyword(s):  
Spatial Distribution ◽  
High Spatial Resolution ◽  
Agb Stars ◽  
Polarization Pattern ◽  
Vlbi Observations ◽  
Very High Spatial Resolution ◽  
Order Of Magnitude ◽  
Circumstellar Shells ◽  
Very High ◽  
Better Than

We have performed VLBA observations of the SiO v = 1 and v = 2 J = 1-0 masers in two AGB stars, TX Cam and IRC +10011. We confirm the ring-like spatial distribution, previously found in several AGB objects, as well as the tangential polarization pattern, already reported for TX Cam. Both properties, that seem to be systematic in this kind of objects, are characteristic of radiatively pumped SiO masers. On the contrary, we do not confirm the previous report on the spatial coincidence between the J = 1-0 v = 1 and 2 masers, a result that would have argued in favor of collisional pumping. We find that both lines sometimes arise from nearby spots, typically separated by 1-2 mas, but are rarely coincident. The discrepancy with previous results is explained by the very high spatial resolution of our observations, ∼ 0.5 mas, an order of magnitude better than in the relevant previously published experiment. Moreover, we have been able to measure a probable rotation of the inner shell of a few km/s. Rotation of circumstellar shells is assumed by the most convincing models explaining the drastic change of symmetry between the AGB envelopes (spherical symmetry) and Proto Planetary Nebulae (axial symmetry).

scholarly journals Influence of Advective Accelerations on Estuarine Exchange at a Chesapeake Bay Tributary

2012 ◽  
Vol 42 (10) ◽  
pp. 1617-1634 ◽  
Author(s):  
Nuvit B. Basdurak ◽  
Arnoldo Valle-Levinson
Keyword(s):  
Spatial Distribution ◽  
Chesapeake Bay ◽  
Momentum Balance ◽  
Exchange Flow ◽  
Hampton Roads ◽  
Relative Contribution ◽  
Advection Term ◽  
Nonlinear Advection ◽  
Order Of Magnitude ◽  
Estuarine Exchange

Abstract The influence of nonlinear advection on estuarine exchange flow was investigated with observations at the transition between the James River and Chesapeake Bay, Hampton Roads, Virginia. Data were collected under different tidal forcing, wind forcing, and river discharge in 2004 and 2005. The relative contribution of nonlinear advective terms to the along-channel momentum balance had the same order of magnitude as pressure gradient and friction, verifying recent analytical and numerical model results. Both the magnitude and the spatial distribution of nonlinear advection showed fortnightly variability. Nonlinear advection was more influential on along-channel flow at spring tides than at neap tides because of increased tidal velocities, in a cross-sectionally averaged sense. The flow structures induced by each nonlinear advective process were investigated for the first time with observations. The lateral advection term υuy was found to enhance laterally sheared exchange acting along with Coriolis forcing at spring tides and opposing it at neap tides. Vertical advection wuz showed similar spatial distribution as υuy at spring tides but was vertically sheared (landward at middepth and seaward in the rest of the water column) at neaps. Longitudinal advection uux augmented landward flow in the channel.

Geology and volcanology of San Venanzo volcanic field (Umbria, Central Italy)

2005 ◽  
Vol 142 (6) ◽  
pp. 683-698 ◽  
Author(s):  
VITTORIO ZANON
Keyword(s):  
Spatial Distribution ◽  
Central Italy ◽  
Volcanic Field ◽  
Tectonic Activity ◽  
Complex Morphology ◽  
Field Evidence ◽  
Field Investigations ◽  
Volcanic Deposits ◽  
Groundwater Reservoir ◽  
History Of

The purpose of this paper is to integrate, or even modify where necessary, the geo-volcanological setting outlined by other authors on the history of the small volcanic field of San Venanzo (Umbria, Central Italy). To attain this goal, new accurate field investigations were carried out in that area, coupled with detailed stratigraphic studies and laboratory analyses, to support field evidence with experimental results. The first objective was to stress the importance of a groundwater reservoir whose interaction with magma at various degrees was responsible not only for the explosive character of volcanism in that area, but also for the complex morphology of the volcanic deposits that are widely scattered on the underlying sedimentary basement. Another objective was to clarify the role played by tectonic activity in enhancing the fast and discontinuous ascent of batches of magma from the mantle to the surface, through two different sets of faults, opened by tectonic unrest into the crust, that were also responsible for the morphology and spatial distribution of volcanic centres. This was considered to be very important in consideration of the still-active stress field of the region. Finally, special attention was focused on the presence of a palaeosol between two eruptive sequences, as it most likely denoted a split in the volcanic activity of this site into two separate phases. This observation leads to the conclusion that, in spite of its eruptive characteristics, the small volcano of San Venanzo is not monogenic. For all of these topics, a number of conclusions have been drawn and they are reported with more data in the following sections of this paper.

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