Mean river water

This estimate of the suspended plus the bed load is from Syvitski, J. P. M., et al (2005), Science 308, 376-380. The total input of dissolved solids in natural river water is estimated from the global mean river water TDS in Table 21.2 (99.6 mg/L) and the river runoff rate from Figure 2.1. 

Table 1.4. Composition and activity coefficients in mean river water (I = 2.08 x 10-3, pH = 7.0).

Composition of mean river water based on Livingstone (1963). f= fraction of total ions which are unpaired. 

A key feature of the above chemical-weathering scenarios is that relatively little atmospheric or biogenic CO2 is involved. Hence, whereas —23% and —77% of solutes, excluding recycled sea salt, found in global mean river water are derived from the atmosphere and rock, respectively (Holland, 1978), atmospheric sources account for a maximum of 3 -11 % of solute in glacial runoff (after Hodson et al., 2000). 

Shown in Table 8.9 are chemical analyses of mean river water and seawater, along with residence times of the species and a comparison of relative concentrations in mean river water and the ocean. As in the discussion of the hydrologic cycle, the residence time of species in seawater, t, equals the amount of that species in the reservoir (the ocean), divided by its rate of input or output (which must be equal at steady state). The input is in streams and groundwaters discharging into the ocean. The output is through adsorption and/or precipitation in and on solids that end up in marine sediments. 

TABLE 8.9 Chemical analyses of mean river water and seawater, along with residence times of the species and a comparison of relative concentrations in mean river water and the ocean... 

Species Mean river water (mg/L) Seawater- (mg/L) Residence time in seawater (my) Concentration in seawater relative to river water... 

This question relates to the chemical analysis of mean river water from Livingstone (1963), which is given... 

Their contribution to the total dissolved load in rivers can be estimated by considering the mean composition of river water and the relative importance of various rocks to weathering. Estimates (18) indicate that evaporites and carbonates contribute approximately 17% and 38%, respectively, of the total dissolved load in the wodd s rivers. The remaining 45% is the result of the weathering of siUcates, underlining the significant role of these minerals in the overall chemical denudation of the earth s surface. 

A widely used instmment for air monitoring is a type of ionization chamber called a Kaimn chamber. Surface contamination is normally detected by means of smears, which are simply disks of filter paper wiped over the suspected surface and counted in a windowless proportional-flow counter. Uptake of tritium by personnel is most effectively monitored by urinalyses normally made by Hquid scintillation counting on a routine or special basis. Environmental monitoring includes surveillance for tritium content of samples of air, rainwater, river water, and milk. 

The studies of U in river waters has enabled to assess the mean activity ratio of the dissolved U flux carried by rivers to ocean. The value of 1.17, based on 50% of the global exported U flux (Table 1), is in the lower range of older estimates based on smaller data sets (e.g., Mangini et al. 1979 Borole et al. 1982). Such an estimate is too low compared to the ratios of seawater. The point has been already raised by... 

Accuracy is often used to describe the overall doubt about a measurement result. It is made up of contributions from both bias and precision. There are a number of definitions in the Standards dealing with quality of measurements [3-5]. They are only different in the detail. The definition of accuracy in ISO 5725-1 1994, is The closeness of agreement between a test result and the accepted reference value . This means it is only appropriate to use this term when discussing a single result. The term accuracy , when applied to a set of observed values, describes the consequence of a combination of random variations and a common systematic error or bias component. It is preferable to express the quality of a result as its uncertainty, which is an estimate of the range of values within which, with a specified degree of confidence, the true value is estimated to lie. For example, the concentration of cadmium in river water is quoted as 83.2 2.2 nmol l-1 this indicates the interval bracketing the best estimate of the true value. Measurement uncertainty is discussed in detail in Chapter 6. 

Also, Amie and Alberto [22] obtained good correlations between mean annual water temperatures, mean annual water temperature ranges and heights for the rivers of the Ebro River basin. Comparing the actual water temperature with the estimated water temperature they observed that some rivers (rivers Jalon, Jiloca, Martin) showed higher temperatures than expected. However, although the authors formulated some hypothesis for such alterations (reservoirs, thermal sources) the available data did not suffice to isolate the actual cause. 

Regarding the effect of reservoirs on water temperature, both heating and cooling effects have been observed. Comparing mean annual water temperatures upstream and downstream from different reservoirs of the river basin, Alberto and Amie [22] observed an increase in water temperature. Instead, Garcia de Jalon et al. [27] observed a decrease in water temperature in summer because of a small capacity reservoir at the River Cimca upstream from Ainsa. The low water temperatures induced a change in the composition of the downstream community. The observed effects of the reservoirs of the lower Ebro River are discussed below. 

In the long term, mean annual water temperature at Escatron, in the medium Ebro River course, shows an increasing trend, as demonstrated by Alberto and Amie [22] for the period 1955-1978 and Prats et al. [32] for the period 1955-2000. During the period 1955-2000, mean annual water temperature increased by 2.3°C. This increase seems to be related to an increase in air temperature and a decrease in discharge. Also, Alberto and Amie [22] suggested it was due to the cumulative effects of reservoirs, urban wastewater, power plants and irrigation. 

The water temperature of the lower Ebro River was measured monthly by Munoz [34] between Xerta and the mouth of the river in the years 1986-1987 (Fig. 3). Her measures showed a clear annual cycle, with minima of 8-10°C in January-February and maxima of 24—29°C in summer. In addition, the annual thermal range was around 16-18°C. The measurements of Val [29] show a similar water temperature cycle in the lower Ebro River downstream from the nuclear plant of Asco. However, in the stretch between the reservoir of Flix and the nuclear power plant of Asco the mean annual water temperature is about 3°C lower than downstream from the nuclear plant [26]. 

Table 3 Total loads (expressed as gram per day per 1,000 inhabitants) of pharmaceuticals detected in WWTP effluents that are afterwards discharged into receiving river waters. Loads are expressed as the range of the amounts detected in each sampling period altogether with average and mean values...

Bisphenol A Production of resins (polycarbonate and epoxy resins). Component in flame retardant production Antioxidant, preservative - River water mean values 0.016 pg L 1 (Europe) and 0.5 pg L"1 (US) [66]. -SW <0.001-1 pg U1 [9] - WW effluents mean values 1.5 pg L-1 [67] Not persistent in surface water. Rapidly biodegraded in aquatic environments [68] and removed in WWTP. Half-life 1-4 days [69] in water. Accumulated in anoxic sediments [9]... 

Thus it can be seen that the mean concentration of DAS1 plus DSBP (pg kgy 1) in sediments is some 16000 times greater than it is in the overlying water layer. In the case of BLS this factor exceeds 250000. Similar large factors have been observed in the case of chlorinated insecticides in river waters i.e. bioaccumulation factors of the order of 104. 

Enhancement of cholesterol solubility by high molecular weight DHS in river water, where solvent extraction of the radiolabeled cholesterol was ineffective as a means of recovery unless the OM content was altered by UV radiation. 

Hites 1978, 1979). The annual mean concentration of phenol in water from the lower Mississippi River was 1.5 ppb (EPA 1980). River water in an unspecified location in the United States was reported to contain 10-100 ppb of phenol (Jungclaus et al. 1978). Phenol was detected, but not quantified, in a Niagara River watershed (Elder et al. 1981) and in 2 of 110 raw water samples analyzed during the National Organic Monitoring Survey (EPA 1980). In the STORET database, 7% of 2,181 data points for U.S. surface waters were positive for the presence of phenol the mean and range of the reported concentrations were 533 ppb and 0.002-46,700 ppb, respectively (EPA 1988c). 

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