Contributions riverine

Since 1916 the sedimentation rate, Region III of Figure 3, has averaged 644 g m-2 yr-1 or 0.3 cm yr 1 or about 5 times the pre-cultural rate. The diversion of the Cedar River (average flow of 20 m3 s 1 into the lake in 1916 provided the water necessary to operate the ship and canal locks and contributes an estimated 4-5 x 107 kg-yr-1 of allochthonous material, Crecelius [7]. This riverine sediment input would contribute to the greater... 

Using the rock cycle as an example, we can compute the turnover time of marine sediments with respect to river input of solid particles from (1) the mass of solids in the marine sediment reservoir (1.0 x 10 g) and (2) the annual rate of river input of particles (1.4 X lO g/y). This yields a turnover time of (1.0 x 10 " g)/(14 x lO g/y) = 71 X lo y. On a global basis, riverine input is the major source of solids buried in marine sediments lesser inputs are contributed by atmospheric feUout, glacial ice debris, hydrothermal processes, and in situ production, primarily by marine plankton. As shown in Figure 1.2, sediments are removed from the ocean by deep burial into the seafloor. The resulting sedimentary rock is either uplifted onto land or subducted into the mantle so the ocean basins never fill up with sediment. As discussed in Chapter 21, if all of the fractional residence times of a substance are known, the sum of their reciprocals provides an estimate of the residence time (Equation 21.17). 

The CCcu appeared to be linearly dependent on the concentration factor only in the upper part of the estuary. No increase in the CCcu couW be observed after concentration at higher salinities. The riverine colloidal material apparently coagulates to particles and floes at increasing salinity in the upper part of the estuary. These floes are retained by the 0.45 ym filter, thus no longer contributing to the complexation capacity of the "dissolved" fraction. This explains the non conservative behaviour of the CCcu n this part of the estuary (see later). Samples taken from the north Atlantic Ocean did not show an increase in CCcu> even aftar a concentration factor 200 times. 

Conley, D.J. (1997) Riverine contribution of biogenic silica to the oceanic silica budget. Limnol. Oceanogr. 42, 774—777. 

Yunker, M.B., Macdonald, R.W., Cretney, W.J., Fowler, B.R., and McLaughlin, F.A. (1993) Alkane, terpene, and ploy cyclic aromatic hydrocarbon geochemistry of the Mackenzie river and Mackenzie shelf riverine contributions to Beaufort Sea coastal sediment. Geochim. Cosmochim. Acta 57, 3041-3061. 

The receipt part of the water balance of the Black Sea consists of the riverine runoff, atmospheric precipitation, and marine water supply via the Bosporus and Kerch Straits. A small contribution is also provided by the ground water delivery. The expenditure part of the balance includes evaporation from the water surface and the removal of the Black Sea waters via the Bosporus and Kerch Straits. The mean annual value of these components of the balance (under certain assumptions) comprises about 816 km3/year, that is, only 0.15% of the total volume of the Black Sea waters. Approximately 354 km3 of riverine waters is annually supplied to the sea of them, up to 200 km3 is contributed by the Danube River. The atmosphere precipitation in the form of rain and snow provides 237 km3 of water. The lower current via the Bosporus Strait annually delivers about 175 km3 of saline waters of the Sea of Marmara, while the Kerch Strait supplies approximately 50 km3 from the Sea of Azov. The mean annual water expenditure for evaporation comprises up to 396 km3 the upper current in the Bosporus Strait removes about 385 km3 of the Black Sea water to the Sea of Marmara, and the water removal via the Kerch Strait to the Sea of Azov makes up to 35 km3. Thus, the receipt part of the balance mostly consists of riverine waters, which comprise about 40% of all the water supplied. This component is characterized by a strong variability. The expenditure part of the balance consists of evaporation and water removal via the Bosporus. Meanwhile, evaporation features a low variability and thus has no significant effect on the variations in the water regime. 

In contrast to Lake Calado, in Lake Camaleao riverine N contributed the majority to the total input (70%, Fig. 14.8). When not inundated, the ATTZ of Lake Camaleao was the location of significant gaseous N output, a finding likely important in most floodplain lakes. Periphyton played a major role in denitrification and nitrogen fixation, a result further supporting the evidence from other lakes that periphyton is a key component in the biogeochemistry and foodwebs of floodplain lakes. 

Fixed N is also transferred from terrestrial to marine ecosystems by riverine and atmospheric vectors, in roughly equal parts (GaUoway et al, 2004). This probably contributed no more than one quarter, and perhaps less than one eighth, of the input flux of fixed N to the pre-industrial ocean (Galloway et al, 2004). Although it has been suggested that the of terrestrial inputs sums to near 0%o (Brandes and... 

Figure 3 Loss of terrestrial OC in deltaic systems, (a) Organic carbon to mineral surface area ratio (OC SA) plotted against bulk stable carbon isotopic compositions for riverine suspended sediments (closed symbols) and deltaic surface sediments (open symbols). A shift to lower OC SA values indicates net loss of organic matter, and a shift to heavier (i.e., C-enriched) isotopic compositions indicates increasing contributions from marine organic matter, (b) The average ( 1 SD) total amount of terrestrial OC persisting in deltaic sediments, based on the changes in OC SA and composition between river suspended sediments and deltaic sediments for four river systems...

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