Rivers concentrations

Moore DG (1967) Amazon and Mississippi River concentrations of uranium, thorium, and radium isotopes. Earth Planet Sci Lett 2 231-234... 

Species (measured parameter) Concentration in the River Concentration in the Well... 

Figure 25.6 The step input (a) By introducing a normalized concentration, C - C0, the step input can be described as a sudden change in the river concentration from 0 for / < 0 to Cin for t > 0. (b) When the step function moves along the aquifer, the front becomes smoother. 05 and 095 are the nondimensional times when C in the aquifer reaches 5% and 95% of Cin, respectively.

Often the concentration of a chemical substance in a river shows periodic fluctuations with typical periods of a day (diurnal fluctuations), a week, or even a year (annual fluctuations). In Chapter 21 we have discussed the response of a completely mixed box to aperiodic input (see Box 21.3). Here the situation is more complex since the fluctuations propagate into the aquifer by diffusion as well as by advection. In addition to the Peclet Number, the period % determines how far the fluctuations are felt within the aquifer and how much the phase shifts relative to the phase of the driving river concentration. Remember that the angular frequency (0 is related to the period T by (0 = 2ulx. If the concentration in the river varies as ... 

Recently, Li et al. (2006) assessed PAH concentrations, distribution between different phases, and transition along the middle and lower reaches of the Yellow River Concentrations of PAHs in water samples from the main stream of Yellow River ranged between 179 and... 

Significant amounts of OCPs were found in water of rivers, estuaries and seas, and generally, sewage water concentrations > river concentrations > estuary concentrations > sea concentrations. Levels of OCPs in sewage from Guangzhou had the highest concentrations of DDTs and HCHs... 

Lake William (104 km2 in area) receives PCBs from the Richard River and rainfall and loses PCBs only by sedimentation. The river concentration is 1.0 ng/ L, and its flow rate is 104 m3/s. The rain concentration is 20 ng/L, and its delivery rate is 80 cm/year. The PCB concentration in the lake s outlets is negligible. What is the PCB flux to the lake s sediment ... 

Input = discharge in rivers x river concentration = 3.6x10- x 0.23 x103 mol yr- ... 

Figure 24. UV spectra (raw and normalised) of the Calavon River (concentration in mg/L).

Raw water samples taken from three locations on the Savannah River were also found to contain levels comparable to the Savannah River estuary samples (Corey and Boni 1976). The estuarine and river concentrations were greater than the Pacific surface water samples, but were on the same order of magnitude as seawater samples taken from Trombay (Bombay,India) (Pillai and Mathew 1976). These results indicate that plutonium is found throughout the globe but that the highest concentrations of plutonium in water are found near source areas. 

Among opioids, CODE, METH, and its metabolite EDDP were the most ubiquitous compormds however, concentrations measured in river waters were usually substantially lower than those of CO and BE. In the Llobregat River, concentrations of these compounds were increasing downstream, reaching valires of 40 ng/L for CODE, 4 ng/L for METH, and 17 ng/L for EDDP (Boleda et al., 2009). MOR was found at low concentrations in some surface water samples collected from the Ebro... 

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