Potential erosion area

The frequency of occurrence plot given in the right panel of Fig. 19.13 confirms that the regions shallower than 30 m are potential erosion areas, where fluffy layers are washed off with a probability of 10% or more. Naturally, the erosion area is smaller and is affected with lower frequencies if the threshold for incident movement is higher, as for example 1.2 cm/s for the bed-load transport of fine sand, or 2 cm/s for its resuspension. 

The following chapter is a case study of how the three problem areas illustrated (dissolved oxygen depletion, erosion/deposition, and potentially toxic trace elements) may be successfully addressed on a major river system using quantitative, semi-quantitative and qualitative approaches respectively. 

The goals of this chapter do not include a "state of the art" literature review which would be appropriate for a more in-depth discussion of one particular problem area. Rather the intent is to illustrate mechanistic approaches to river quality assessment using the three globally relevant water quality problem areas discussed in the previous chapter dissolved oxygen depletion, erosion/deposition, and potentially toxic trace elements. The information provided does not include all rationale, methology or approaches used in the study as this is beyond the scope of the chapter. Additional general information on application of the intensive river quality assessment approach in the Willamette River basin may be found elsewhere (4-9, 11-14, 17). 

For most pH values and at most potentials, titanium is passive and no corrosion takes place. This is revealed by the white areas of Fig. 23.2. However, there are some exceptions. Consider alkaline attack (Fig. 23.3). It is occasionally assumed that titanium cannot be used in the alkaline conditions of hypochlorite and excess alkalinity, etc. Corrosion data do not sustain this assumption. It is only at high temperatures and high concentrations that corrosion becomes a factor of concern, as does the increase in erosion under such conditions. 

Table 1 of a paper by Murr (2) lists problems and/or concerns related to specific interface materials and specific components of SECS. In Table 2 of the same work, he related topical study areas and/or research problems to S/S, S/L, S/G, L/L, and L/G interfaces. It is also useful to divide interface science into specific topical areas of study and consider how these will apply to interfaces in solar materials. These study areas are thin films grain, phase, and interfacial boundaries oxidation and corrosion adhesion semiconductors surface processes, chemisorption, and catalysis abrasion and erosion photon-assisted surface reactions and photoelectrochemistry and interface characterization methods. The actual or potential solar applications, research issues and/or concerns, and needs and opportunities are presented in the proceedings of a recent Workshop (4) and summarized in a recent review (3). 

Co-deposition of tritium with carbon is potentially the major T repository for ITER even if the use of carbon is minimized to the divertor strike plates. Retention by other mechanisms is expected to be low and to contribute only marginally to the in-vessel tritium-uptake (Sect. 12.4). For this reason the focus here is on some recent experimental findings associated with ( ) carbon erosion and deposition patterns in existing tokamaks, ( ) hydrocarbon film formation in areas of the divertor hidden from the plasma, and (in) mixed-material effects. 

Slope stabilization is just one potential application for composites in the broad area of erosion control. Several other related applications are bridge abutments, freeway cuts, storage tank embankments, mine tailings, sand dunes, and areas of turbulent water flow. 

In addition to greatly altering P distribution within the pasture area due to the patchy distribution of excretion, cattle can also indirectly enhance the potential of P movement in the landscape. This is because cattle transit within the pasture area can create trails which are channels for runoff, and overgrazing and trampling may result in open areas that facilitate losses through runoff of particulate and dissolved P and erosion of surface soil and plant material. Since most of the excreted P is in the feces... 

Mucositis and stomatitis are potentially severe and dose-hmiting adverse effects of the anthracyclines. Both the frequency and the severity are dose-dependent (56,69). Their onset and recovery generaUy parallel the hematological toxicity, but they can occur earlier (5-10 days after treatment starts). Areas of painful erosions, mainly along the side of the tongue and on the subhngual mucosa, are common. Mucositis occurs in about 9% of patients who receive oral idambicin in standard doses (27). 

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