River dissolved solid discharge

Four of the 10 rivers with highest dissolved solid discharge (Salween, MacKenzie, St Lawrence, and Rhine) in Table 3 are not among the world leaders in... 

The last four rivers in Table 3 reflect the diversity of rivers with similar dissolved solid discharges. The Cunene, in Angola, is an arid river that discharges about as much water as the Citandy in Indonesia, but drains more than 20 times the watershed area. As such, total dissolved solid (TDS) values for the two rivers are similar (51 vs 62 mg 1 ), but the dissolved yield (TDS divided by basin area) of the Cunene is < 1 % that of the Citandy. In contrast, the Ems River, in Germany, has a similar dissolved load to the Citandy, but concentrations are roughly three times greater. 

Figure 16.10 Trace element exportation fluxes from the Amazon River. Errors bars represent the sum of errors assuming the following uncertainties water discharge (10%), solid discharge (10%), analytical errors of dissolved concentrations (10%) and of particulate concentrations (5%).

The amount of dissolved solids in river water increases with the distance from its source. The chief sources of pollution of river-water are by the discharge into them of the sewage of towns and cities, or of the waste products of factories. 

Table 4 Cumulative oceanic areas, drainage basin areas, and discharge of water, suspended and dissolved solids of rivers draining into various areas of the global ocean...

Table 1 Database oftrace element concentration in the dissolved load (<0.2 xm) of rivers. All concentrations inppb (p-gL )except forRa(fgL and Os (pgL ). DOC, TSS, TDS are Dissolved Organic Carbon (mgL ), total suspended solid (mgL ), and total dissolved solutes (mgL ). Water discharge and surface are in s and 10 Km, respectively. 

Whereas the composition of dissolved main solid compounds in seawater is rather constant all over the oceans, the freshwater in the Baltic Sea outbalanced by river discharge is dominated by calcium bicarbonate. For this reason, significant anomalies are observed in Baltic waters from the standard composition of seawater (Nehring and Rohde, 1966), in particular in the brackish surface water, with amount increasing toward the eastern and northern margins of the Baltic Sea. Directly measured densities of Baltic water compared with density determined from the seawater equation of state with Baltic water salinity measured by chlorinity titration resulted in a deviation of up to 0.123 kg/m (Millero and Kremling, 1976). This may result in uncertainties in estimating the thermodynamic properties of Baltic water, for example, the vertical stability. 

Reactions in natural systems are controlled by the degree to which the equilibrium is disturbed. In this case nonequilibrium conditions have to be considered separately for the dissolved phase and the suspended solid phase. Disturbances of natural equilibria, for example, in a river, are most frequently found downstream of wastewater discharges, etc. To quantify concentration-dependent reaction rates the two concentration fields resulting from mixing must be described. This is done using known and tested models to describe turbulent diflFusion of dissolved and undissolved suspended substances (26). 

For many years municipal sewage treatment plants had only primary treatment, followed by chlorination of the treated wastewater (see Section 11.12) before it was discharged into a suitable river or stream. Chlorination kills any remaining harmful pathogens. Presumably, natural processes would get rid of the remaining solids and dissolved organic matter. 

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