Losses from erosion

When very high velocities are encountered, metal loss from erosion-corrosion can be general. T ically, however, erosion-corrosion produces localized metal loss in immediate proximity to the disrupted flow. Smooth, rolling, wavelike surface contours are often produced, or distinct, horseshoe-shaped depressions (Fig. 11.1) or comet tails... 

Figure 11.17 Metal loss from erosion-corrosion in its early stages. Note the elongated depressions aligned with water flow.

The results of the calculations reveal that the Ru losses from erosion, dissolution and open circuit corrosion (assuming shut-downs at a frequency of 12 per year), occurring... 

Chemical, cultural, and mechanical weed control practices have been relatively successful ia reducing yield losses from weeds (448). However, herbicide-resistant weed populations, soil erosion, pesticide persistence ia the environment, and other problems associated with technologies used (ca 1993) to control weeds have raised concerns for the long-term efficacy and sustainability of herbicide-dependent crop production practices (449). These concerns, coupled with ever-increasing demands for food and fiber, contribute to the need for innovative weed management strategies (450). 

If the amount of metal removal by erosion is significant the surface will probably be continually active. Metal loss will be the additive effect of erosion and active corrosion. Sometimes the erosion rate is higher than that of active corrosion. The material selection judgment can then disregard coirosion and proceed on the basis of erosion resistance provided the corrosion rates of aetive surfaces of the alloys considered are not much different. As an example of magnitudes, a good high-chromium iron may lose metal from erosion only a tenth as fast as do the usual stainless steels. 

In addition to a complete water balance, EPIC estimates plant biomass production, fertilizer use, wind and water erosion, loss of nitrogen and phosphorus from the soil, and the effect of nutrient loss from the soil on plant growth. 

Erosion can seriously effect a landfill closure by disrupting the functioning of drainage layers and surface water and LCRSs. Heavy erosion could lead to the exposure of the waste itself. For this reason, it is important to predict the amount of erosion that will occur at a site and reinforce the facility accordingly. The Universal Soil Loss Equation shown below can be used to determine soil loss from water erosion5 ... 

Figure 26.34 can be used to find the soil loss ratio due to the slope of the site as used in the Universal Soil Loss Equation. Loss from wind erosion can be determined by the following equation ... 

Mlrex. Mirex does not leach into the soil profile and is predicted to volatilize only slowly. There Is no evidence for any rapid transformation so it should be considered persistent. Because It is so strongly adsorbed to the soil and stays on the surface, a major loss from terrestrial systems would probably be erosion and transport Into surface waters. 

It is important to distinguish between erosion and degradation. Erosion is mass loss from a bioerodible polymer and may be a consequence of polymer dissolution or degradation of the polymer backbone, followed by dissolution of the degradation products. Degradation typically occurs by hydrolysis of the polymer backbone, the kinetics of which is a function of the polymer chemistry. Thus, erosion is the sum of several elementary processes, one of which may be polymer degradation. 

Ru losses can occur during electrolysis, as well as those due to shorting in mercury cell operations, from erosion, loss of Ru-based intermediates involved during the course of chlorine and oxygen evolution reactions and during shut-downs. 

Erosive lesions. We determined the daily calcium loss from the specimens by combining the releases of calcium in consecutive incubations with acid and either collagenase or buffer. We calculated the cumulative calcium loss for each specimen by combining the daily calcium losses. 

White, A.W., A.P. Barnett, B.G. Wright, and J.H. Holladay (1967). Atrazine losses from fallow land caused by runoff and erosion. Environ. Sci. Technol., 1 740-744. 

Mass loss from the samples was measured using an analytical balance with an accuracy of 0.1 mg. Wear volume was calculated from the mass loss and the bulk density of each material. Cumulative volume loss was plotted as a function of the amount of erodent impacting on the surface. The steady state erosion rate, defined as the volume loss from the specimen per unit mass of erodent used, was determined from the slope of the linear part of the plot of volume loss against mass of erodent. 

Q8 Since iron deficiency may follow pathological blood loss, some investigation of possible sources of blood loss, particularly into the gut, is advised before treatment of the anaemia is started. Haemorrhage into the gut, for example from erosion or ulceration of the stomach or from sites in the large intestine in colorectal cancer, can be simply detected by testing for (occult) blood in the faeces. 

---