River riverine input

Guan YF, Wang JZ, Ni HG, Luo XJ, Mai BX, Zeng EY (2007) Riverine inputs of polybrominated diphenyl ethers from the Pearl River Delta (China) to the coastal ocean. Environ Sci Technol 41(17) 6007-6013. doi 10.1021/es070782x... 

POCs proportions and content of POCs in river waters compared with maximum permissible concentration (MPC, for DDT, HCH and PCB, are equal to 100,20 and 1 ppb correspondingly for water and 100,100 and 100 for bottom sediments) behavior of toxic compounds in the water body factors promoting an increase of the ecological risk of polluted riverine input into the Caspian Sea (Figure 4). 

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 overall effect of the terrestrial weathering reactions has been the addition of the major ions, DSi, and alkalinity to river water and the removal of O2, and CO2 from the atmosphere. Because the major ions are present in high concentrations in crustal rocks and are relatively soluble, they have become the most abimdant solutes in seawater. Mass-wise, the annual flux of solids from river runoff (1.55 x 10 g/y) in the pre-Anthropocene was about three times greater than that of the solutes (0.42 x 10 g/y). The aeolian dust flux (0.045 X 10 g/y) to the ocean is about 30 times less than the river solids input. Although most of the riverine solids are deposited on the continental margin, their input has a significant impact on seawater chemistry because most of these particles are clay minerals that have cations adsorbed to their surfaces. Some of these cations are desorbed... 

River runoff The transport of water, solutes, and hthogenous particles from the continents to the ocean as a result of riverine input. 

The oceanic Si system was assumed to be in a steady state with inputs from rivers and other minor sources being balanced by outputs during burial (Treguer et al., 1995). However, between these inputs and outputs there is a significant amount of recycling that occurs through biological processes. For example, riverine inputs of Si to the oceans are... 

Some amounts of sand riverine sediments are transported in channels in the form of sand ripples, waves and dunes formed on the river bed under the influence of the near-bottom currents. This sediment load (called bedload) usually comprises about 10% of the suspended sediment load. Taking into account this fact, we find that the total river sediment input to the Black Sea may range up to 84 x 106 tyear-1. 

Nitrogen fluxes (in Tg N year ) are reported for contemporary conditions, with estimates under pristine conditions indicated in parentheses. Flux of nitrogen delivered from rivers and estuaries is the direct input of rivers that discharge onto the continental shelf plus the riverine input into estuaries, minus nitrogen consumed in estuaries. Atmospheric nitrogen deposition estimates in this table are those directly onto the waters of the continental shelf and do not include deposition onto the landscape (which is part of the flux from rivers and estuaries). The flux from the deep ocean represents the advection of nitrate-rich deep Atlantic water onto the continental shelf Data in this table are from Howarth (1998). 

Asia. Large rivers of Asia are clearly the less well documented in terms of trace-element concentrations. This is mainly due to their low abundances of trace elements, probably related to their high pH character. A couple of studies have focused on the riverine input of metals to the Arctic and Pacihc oceans. Himalayan rivers have not been documented for REEs (except the Indus river), but have been analyzed for particular elements such as strontium, uranium, osmium, and radium. There is clearly a need for data on trace elements in the rivers of Asia, particularly in the highly turbid peri-Himalayan rivers. 

Accumulation of point sources from land use of petroleum products also can affect surface waters. For example, urban riverine inputs of volatile hydrocarbons to the marine environment have been studied in the coastal waters of Spain by Gomez-Belinchon et al. (1991). Volatile petroleum hydrocarbon inputs from two rivers were found to account for a mass flux of 47tyr and 96tyr of alkylbenzenes and 38tyr and 66 tyr of w-alkanes each. Although this was a significant mass flux, the... 

It has been shown that the main part of both soluble (53%) and particulate (> 99%) nitrogen was inputting into the Yellow sea from Northern China in spite of only 30% excess of river water discharge from the Chinese area. Totally riverine input from watershed drainage basin was equal to 52% from input values (2,581 kt/yr). Both wet and dry depositions were responsible for 20 and 22 % from input values with relatively small values of N fixation in marine waters. Denitrification is the main output items (37%) with similar values of sedimentation and water exchange with East the China Sea (7 and 8% from total input) and with negligible values of losses as N2O (< 1%). 

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