Clear water rivers

Based on chemical measurements for river water and atmospheric particles, it is clear that river inflow is by far the most important mechanism for the delivery of dissolved major ions and elements to the ocean. This is not the case for all elements some of the trace metals such as iron and lead have important sources from atmospheric dust, but our discussion will focus on the flux of major elements to the ocean. The concentration and origin of the major ions to river water is presented in Table 2.1. Weathering of rocks on land is the origin of the cations, Na+, Mg ", Ca " and K", whereas the source of the anions Cl, SO4 and HCOj is partly from rock weathering and partly from the gases CO2, SO2 and HCl that are delivered to the atmosphere via volcanic emissions over geologic time. 

The above process, coupled with the fact that most carbonate-secreting organisms only thrive in clear waters — remote from rivers carrying significant amounts of solids washed from the land — accounts for the remarkably high purities of many carbonate deposits, which often exceed 98% of calcium plus magnesium carbonates. 

On the other side of the world is a bright magenta river made by different carbon-chain pigments. Located in Columbia, this river is officially Cano Cristales and unofficially The River of Five Colors. Since it was discovered by the Internet, it has graced countless computer monitors with pictures of green, pink, orange, yellow, and red mosses and plants growing under crystal-clear waters. 

The result of the expert s investigation was clear The Rhine can no longer be considered a source of healthy, potable water . But this conclusion had no effect. No additional protective measures were required, aside from mechanical treatment of municipal wastes. Nor was industrial waste made an issue. Instead, the opposite approach was taken. Blame was placed on the individual Over its course, a river like the Rhine takes on, aside from the run-in from cities and streams, many substances originating directly or indirectly in the private household so that everyone who drinks from the apparently clear waters must take responsibility for danger to his health . In so doing, the Federal Ministry of Health absolved all the parties that discharged into the river. 

Global warming would also be expected to influence surface waters such as lakes and streams, through changes induced in the hydrologic cycle. However, the last published report of the IPCC states no clear evidence of widespread change in annual streamflows and peak discharges of rivers in the world (IPCC, 1995, p. 158). Wliile lake and inland sea levels have fluctuated, the IPCC also points out that local effects make it difficult to use lake levels to monitor climate variations. 

The influence that variations of temperature and levels of atmospheric CO2 and O2 have on chemical weathering are more subtle. Temperature appears to have a direct effect on weathering rate (White and Blum, 1995). The silica concentration of rivers (Meybeck, 1979, 1987) and the alkalinity of ground waters in carbonate terrains (Harmon et al., 1975) are both positively correlated with temperature variations. It is not clear, however, whether temperature-related variations in weathering rates are largely due to variations in vegetational activity that parallel temperature variations. 

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