Riverine

More CO2 can actually be absorbed chemically into the ocean than the above reaction sequence suggests. Terrestrial weathering of rocks containing carbonate, such as limestone, and subsequent aerial or riverine transport, means that the ocean is enriched in carbonate. Keeping and Kj constant implies, through eqns. (3) and (4), that enhancing the oceanic [COj ] leads to a greater level of... 

Global uranium flux calculations have typically been based on the following two assumptions (a) riverine-end member concentrations of dissolved uranium are relatively constant, and (b) no significant input or removal of uranium occurs in coastal environments. Other sources of uranium to the ocean may include mantle emanations, diffusion through pore waters of deep-sea sediments, leaching of river-borne sediments by seawater," and remobilization through reduction of a Fe-Mn carrier phase. However, there is still considerable debate... 

If uranium is internally cycled in coastal environments or if the riverine delivery of U shows some variability, residence time estimates (regardless of their precision) cannot be sensitive indicators of oceanic uranium reactivity. Based on very precise measurements of dissolved uranium in the open ocean, Chen et alJ concluded that uranium may be somewhat more reactive in marine environments than previously inferred. Furthermore, recent studies in high-energy coastal environments " indicate that uranium may be actively cycled and repartitioned (non-conservative) from one phase to the next. 

In a continual biocoenosis test (Riverine biocoenosis model) for LAS the biocoenotic NOEC value of >0.65 mg/L has been determined. The test was carried out with a starting concentration of 1.1 mg/L LAS/L over a period of 5 weeks. The NOEC value represents the effect caused by the original detergent and the effects caused by the catabolites as well [297]. The NOEC value shows that biocoenosis reacts more sensitively to compounds than the most sensitive laboratory species, which according to general opinion should not be generalized. 

The material transported by rivers consists of dissolved ions (dissolved load), sediment suspended in the flow (suspended load), and sediment transported along the bed of the river (bedload). The total load and the proportion of the load represented by these phases varies widely among rivers in different environments. In particular, climate, topography, and erosion influence the amount and composition of riverine sediment loads. 

Fig. 5 Decrease of surface water and the effects on the longitudinal distribution of riverine habitats. During high flow (a) surface habitats, i.e. riffle (fast flowing sections) and pools (slow flowing sections), are available. Drying first affects the surface waters (b), causing fragmentation and the formation of remaining pools (c). During this phase the hyporheic compartment is also restricted to the pool habitats. Finally, both the superficial and hyporheic compartments dry completely up, and potential refuge for the aquatic biota disappear...

Pesce S, Fajon C, Bardot C, Bonnemoy F, Portelli C, Bohatier J (2006) Effect of the phenylurea herbicide diuron on natural riverine microbial communities in an experimental study. Aquat Toxicol 78 303... 

Larson SJ, Capel PD, Goolsby DA, et al. 1995. Relations between pesticide use and riverine flux in the Mississippi River basin. Chemosphere 31 3305-3321. 

Marches JR, SA Owen, GF White, WA House, NJ Russell (1994) SDS-degrading bacteria attach to riverine sediment in response to the surfactant or its primary degradation product dodecan-l-ol. Microbiology (UK) 140 2999-3006. 

Riverine Mink Adult Fur Widespread distribution and easily studied existing database on exposure and effects sensitivity to Hg... 

This hydrothermal Mn flux from back-arc basins is less than the value of riverine Mn flux (0.49 x 10 mol/year). Hydrothermal Mn flux from midoceanic ridge is estimated as (1.1-3.4) x 10 mol/year (Elderfield and Schultz, 1996) which is one to two order of magnitudes greater than the hydrothermal Mn flux from back-arc basins. 

Ba concentration of hydrothermal solution from back-arc basins ranges from 5.3 p.mol/kg-H20 (North Fiji Basin) to 100 p.mol/kg-H20 (Izu-Bonin Suiyo SM) (Gamo, 1995). Assuming that Ba concentration is (20-60) p.mol/kg H2O and seawater cycling rate is 1.8 x 10 g/year, we obtain Ba flux as (3-66) x 10 mol/year. This is greater than or comparable to that of midoceanic ridge flux (2.4-13 x 10 mol/year) (Elderfield and Schultz, 1996) and is comparable to or greater than that of riverine Ba flux (1 x 10 mol/year) (Elderfield and Schultz, 1996). 

Yang H-S, Hwang D-W Kim G (2002) Factors controlling excess radium in the Nakdong River estuary, Korea submarine groundwater discharge versus desorption from riverine particles. Marine Chem 78 1-8... 

Ku 1965). However, the wide range in riverine values (0 to 2000 Cochran 1982) suggests that the elevation of the marine value above secular equilibrium results from a complex combination of weathering and alpha-recoil processes (see above). Thus, it is possible that the marine value has changed by small amounts with time. In practice, the main impediment to a chronometer is the sensitivity of to... 

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