Sediment-water interactions

Moore WS, Demaster DJ, Smoak JM, McKee BA, Swarzenski PW (1996) Radionuclide tracers of sediment-water interactions on the Amazon shelf. Cont Shelf Res 16 645-665 Moran SB, Moore RM (1989) The distribution of colloidal aluminum and organic carbon in coastal and open ocean waters offNova Scotia. Geochim Cosmochim Acta 53 2519-2527 Nozaki Y (1991) The systematics and kinetics of U/Th decay series nuchdes in ocean water. Rev Aquatic Sci 4 75-105... 

In aquatic environments, Spear (1981) spotlights three research needs (1) development of analytical procedures for measurement of individual dissolved zinc species, notably the aquo ion and zinc chloride, and for nondissolved species that occur in natural waters (2) separation of natural from anthropogenic influences of sediment-water interactions on flux rates, with emphasis on anoxic conditions, the role of microorganisms, and the stability of organozinc complexes and (3) establishment of toxicity thresholds for aquatic organisms based on bioaccumulation and survival to determine the critical dose and the critical dose rate, with emphasis on aquatic communities inhabiting locales where zinc is deposited in sediments. These research needs are still valid. 

A series of experiments was also conducted by Bowman et al. [34] to ascertain the effects of differing environmental factors on the sediment-water interactions of natural estrogens (estradiol and estrone) under estuarine conditions. Sorption onto sediment particles was in this case relatively slow, with sorption equilibrium being reached in about 10 and 170 h for estrone and estradiol, respectively. On the other hand, true partition coefficients calculated on colloids were found to be around two orders of magnitude greater that those on sediment particles. Hence, it was concluded that under estuarine conditions, and in comparison to other more hydrophobic compounds, both estrone and estradiol... 

According to Table 23.6, for both congeners the sediment-water interaction contributes 21% to the total removal rate. Most of this (about 98%) is attributed to diffusive exchange. 

In Part 2 of the PCB story, we introduced the exchange between the water column and the surface sediments in exactly the same way as we describe air/water exchange. That is, we used an exchange velocity, vsedex, or the corresponding exchange rate, ksedex (Table 23.6). Since at this stage the sediment concentration was treated as an external parameter (like the concentration in the air, Ca), this model refinement is not meant to produce new concentrations. Rather we wanted to find out how much the sediment-water interaction would contribute to the total elimination rate of the PCBs from the lake and how it would affect the time to steady-state of the system. As shown in Table 23.6, the contribution of sedex to the total rate is about 20% for both congeners. Furthermore, it turned out that diffusion between the lake and the sediment pore water was much more important than sediment resuspension and reequilibration, at least for the specific assumptions made to describe the physics and sorption equilibria at the sediment surface. 

Compared to the situation in lakes, the sediment-water interactions in rivers are more complex. Because the flow velocity is constantly changing, particles may either settle at the bottom or be resuspended and deposited again further downstream. In order to adequately describe the effect of these processes on the concentration of a chemical in the river, we would need a coupled water-sediment model with which the profile of the chemical along the river of both the aqueous concentration in the river and the concentration in the sediment bed are described. This is a task to be left to numerical modeling. We choose a simpler approach by approximating the net deposition of the particles and the chemicals sorbed to them as a linear process (see Eqs. 23-16 and 23-17) ... 

Besides interacting with suspended particles, a chemical also undergoes direct exchange at the sediment surface by diffusion and advection into the hyporheic zone. Furthermore, resuspension followed by exchange between water and particles also adds to the sediment-water interaction. These processes have been extensively discussed in Chapter 23, especially in Box 23.2. There we concluded that the effect from the different mechanisms can be combined into a flux of the form (see Eq. 23-25) ... 

The second example includes the influence of sorption and sediment-water interaction, processes which were not relevant for the case of chloroform. We choose the real case of a chemical pollution of the River Rhine. On November 1, 1986, a fire destroyed a storehouse at Schweizerhalle near Basel (Switzerland). During the fighting of the fire, several tons of various pesticides and other chemicals were flushed into the River Rhine (Wanner et al., 1989). One of the major constituents discharged into the river was disulfoton, an insecticide. An estimated quantity of 3.3 metric tons reached the river within a time period of about 12 hours leading to a massive killing of fish and other aquatic organisms. 

Explain the difference between diffusive sediment-water exchange and the sediment-water interaction caused by ripples on a sandy river bottom. 

Some Conceptual Ideas on Its Significance for Sediment-Water Interactions... 

This chapter presents some implications for sediment-water interactions derived from the findings of our experimental study. Some hypotheses are formulated concerning the coupling of iron and sulfur in sedimentary environments. 

The biofilm concept, applied to sediment-water interactions, breaks with classical strategies to model early diagenesis (i.e., the vertical redox zonation). Although far from completely developed, this concept may overcome modeling problems, such as an adequate description of recycling of substances. 

Simulation of Sediment-Water Interactions. To investigate factors affecting the flux of Mn across the sediment-water interface, we in-... 

Presley, B.J., and Trefrey, J.H. (1980) Sediment-water interactions and the geochemistry of interstitial waters. In Chemistry and Biogeochemistry of Estuaries (Olausson, E., and Cato, I., eds.), pp. 187-222, John Wiley, New York. 

Moore, W. S., D. J. DeMaster, J. M. Smoak, B. A. McKee, and P. W. Swarzenski. 1996. "Radionuclide tracers of sediment-water interaction on the Amazon shelf." Continental Shelf Research 16 645-666. 

Jackson, K. S., Jonasson, I. R., and Skippen, G. B. (1978). The nature of metal-sediment-water interactions in freshwater bodies, with emphasis on the role of organic matter. Earth Sci. Rev. 14, 97-146. 

Radionuclide behaviour sediment-water interactions, sediment behaviour... 

Arakel, A.V., Jacobson, G. Layons, W.B. (1990) Sediment-water interaction as a control on geochemical evolution of playa lake systems in the Australian arid interior. Hydrobiologia, 197, 1-12. 

The long residence time of the bottom water also makes fjords suitable for examining the importance of sediment-water interactions (Sternbeck etal., 1999), including the release of re-mineralized nutrients to the bottom water, the release of contaminants from sediments, and the exchange of gases. 

Contents indude kinetics of toxicants, sediment-water interactions, and mixing zone modeling. 

Jonasson, I.R. (1977) Geochemistry of sediment/water interactions of metals, including observations on availability. In The Fluvial Transport of Sediment-Associated Nutrients and Contaminants, ed. 

Song Y. and Muller G. (1999) Sediment—Water Interactions in Anoxic Freshwater Sediments Mobility of Heavy Metals and Nutrients. Springer-Verlag, Berlin-Heidelberg. 

Appleby, P. G., 1997. Sediment records of fallout radionuclides and their application to studies of sediment-water interactions. Wat. Air Soil Pollut. 99 573-586. 

David Hamilton (modeling of water quality in lakes and reservoirs sediment-water interactions in lakes boom-forming algae, particularly cyanobacteria ice cover in lakes). Environmental Research Institute (ERl), University of Waikato, Waikato... 

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