Discharge of rivers

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. 

Many important erosion-related phenomena are episodic and infrequent, such as flash floods, landslides, and glaciations, while others such as orogenesis and soil formation involve time scales that exceed those of major climate fluctuations. In either case, the time scale of human existence is too short to make adequate observations. Consequently, it is difficult to directly estimate the rates or characterize the effects of such phenomena on erosion products. The key to understanding weathering and erosion, on a continental scale, is to decipher the relationship between landforms, the processes that produce them, and the chemistry and discharge of river-borne materials. 

X 10 yr) and ends with stable ° Pb, after emission of eight alpha (a) and six beta (jS) particles. The thorium decay series begins with Th (ti/2 = 1.41 X 10 °yr) and ends with stable ° Pb, after emission of six alpha and four beta particles. Two isotopes of radium and Th are important tracer isotopes in the thorium decay chain. The actinium decay series begins with (ti/2 = 7.04 X 10 yr) and ends with stable Pb after emission of seven alpha and four beta particles. The actinium decay series includes important isotopes of actinium and protactinium. These primordial radionuclides, as products of continental weathering, enter the ocean primarily by the discharge of rivers. However, as we shall see, there are notable exceptions to this generality. 

The annual discharge of rivers in China contributes 7% of the total global riverine discharge. They play a significant role in biogeochemical processes in China marginal seas (Song, 1997 2004). 

Environmental Concerns. Dyes, because they are intensely colored, present special problems in effluent discharge even a very small amount is noticeable. However, the effect is more aesthetically displeasing rather than ha2ardous, eg, red dyes discharged into rivers and oceans. Of more concern is the discharge of toxic heavy metals such as mercury and chromium. 

Rapid indtistrializtuion has created many problems for the treatment and dispostil of industrial wtistes which are mtiinly responsible for the pollution of rivers, ponds and ftirmlands, when they are discharged directly, without proper treatment. 

Table 16.16 Typical consent conditions for the discharge of industrial effluent to rivers and streams (UK)...

Figure 4. Discharge of suspended sediment from world rivers in 10 tons ear. Sediment yield in tons/km ear for major drainage basins is shown by pattern (see key).

The Willamette River Basin, Oregon serves as an excellent case study of river quality assessment for a number of reasons. First, the Willamette River has been cited internationally as a classic example of how water quality can be restored from a previously poor quality waterway (1-3). Second, excellent background data were available, particularly on hydrology. Third, at the time most of these studies were initiated, the Willamette River was the largest river in the U.S. for which all point-source discharges were receiving secondary wastewater treatment. 

Mass Balance Estimates. Based on National Pollutant Discharge Elimination System monitoring reports, the total daily discharge of trace elements into the main stem Willamette River is of the order of 100 pounds per day. Seventy-five percent of the total is zinc with the bulk of the remainder due to chromium and copper. Table 6 identifies industrial and natural sources of trace elements into the Willamette basin. The table indicates that an average of 97 percent of all trace element loading to the basin is natural in origin. The natural component is due to weathering of soil and rocks in the basin and this... 

Earth (Li, 1976). The high denudation rate is a reflection of the poorly lithifled, highly tecton-ized nature of the sedimentary rocks that compose the island. Sediment-yield data compiled by Milliman and Meade (1983) and Milliman and Syvitski (1992) indicate that island arcs and mountain belts in the tropical and subtropical west Pacific may contribute as more than 22% of all solid material discharged by rivers into the ocean. Furthermore, the tropical mountainous areas in southeast Asia and India may contribute another 33%. 

Table 10-12 Number of times river constituents have passed through the ocean in 10 years assuming present annual worldwide river discharge, mean dissolved constituent concentration of rivers and ocean, and ocean volume of 1.37 x 10 L (amounts in lO kg)...

Liquete C, Canals M, Ludwig W, Amau P (2009) Sediment discharge of the rivers of Catalonia, NE Spain, and the influence of human impacts. J Hydrol 366 76-88... 

It is well documented that WWTP are major contributors of pharmaceuticals and illicit drugs in the aquatic environment, due to their incomplete removal in conventional activated sludge (CAS) treatment, resulting in important loads discharged into river waters through effluent wastewaters (Tables 1 and 2). 

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