Fate and movement of selenium from drainage sediments disposed onto soil with and without vegetation.

Disposal options for salty and selenium-laden agricultural drainage sediments are needed to protect the agricultural ecosystem in Central California. Thus, a 7-year pilot-scale field study evaluated the effects of disposing Se-laden drainage sediment onto soil that was planted with either salado grass (Sporobolus airoides 'salado') or cordgrass (Spartina patens 'Flageo'), or on soil left bare with and without irrigation. Significant decreases in salinity and water-extractable and total soil Se concentrations were observed in all treatments to a depth 30 cm, while water extractable Se and salinity increased most significantly between 30 and 60 cm. Total yields increased over time for both species, while plant Se concentrations were ≈10 and 12 mg kg(-1) DM for salado and cordgrass, respectively. The results show that Se and soluble salts disposed of as Se-laden drainage sediment onto light textured soils will significantly migrate to lower depths with or without vegetation.

Reflection and transmission of plane unbounded electromagnetic waves at an absorbing-nonabsorbing interface with numerical calculations for an ocean-air interface.

The problem of how plane unbounded electromagnetic waves in an absorbing medium are reflected and transmitted at an interface between an absorbing medium and a nonabsorbing medium is a problem of much current interest. In this paper, we will present a Maxwellian boundary-type solution to this problem in which the forms of the E and H components are determined from Maxwell's equations and the boundary conditions, and the radiant fluxes, represented by the Poynting vector, evaluated in both media. From these radiant fluxes, it is possible to determine the forms of the radiant flux flow lines and to see how the propagation characteristics differ in the two media. In the second medium, we again find, as in total internal reflection [A. I. Mahan and C. V. Bitterli, Appl. Opt. 17, 509 (1978)], that inhomogeneous nontransverse waves appear, whose planes of constant phase are normal to the refracted rays and whose planes of constant amplitude are parallel to these refracted rays. Because of these inhomogeneous waves, the second medium, although nonabsorbing under more familiar conditions, now exhibits refractive indices and absorption coefficients, which are functions of the more conventional optical constants and the angle of incidence, and new laws for reflection and transmission appear along the interface for both polarizations. These equations have been applied specifically to an ocean-air interface for a frequency of 100 Hz, and extensive calculations were carried out in which the radiant fluxes and their associated radiant flux flow line forms were determined along the interface and at other points outside the interface for both polarizations under steady state, time changing, and time average conditions. The radiant flux flow lines in the air above the ocean take the forms of up and over radiant fluxes, some of which are trapped above the interface and the remaining flow lines come out of the interface and return to the interface. These ideas are extensions of our earlier work on total internal reflection and show how the radiant fluxes and their associated flow lines in the second medium can be changed markedly by simply making the incident medium absorbing.

Total internal reflection: a deeper look.

In the present paper, we have presented a Maxwellian boundary-type solution for total internal reflection with unbounded incident waves at an interface between two nonabsorbing media, in which the instantaneous, time varying, and time averaged radiant fluxes have been determined at all points in the two media. Solutions for the s and p polarizations were found for which the instantaneous tangential E and H components and normal components of the radiant flux were continuous in crossing the interface. From these radiant fluxes, it was possible to derive equations for the flow lines, to determine the instantaneous radiant fluxes along these flow lines, and to see how the methods of propagation differed in the two media and for the two polarizations. At the interface, the flow lines and their radiant fluxes experience unusual reflection and refraction processes, follow curved flow lines in the second medium, and return into the first medium with boundary conditions, which are mirror images of those at the points of incidence. These unfamiliar processes in the second medium are due to inhomogeneous waves, whose properties have not been understood. When these instantaneous solutions are extended to time varying and time averaged radiant fluxes, it is interesting to see how incident planes of constant radiant flux and phase experience such complex processes in the second medium and are still able to generate other reflected planes of constant radiant flux and phase in the first medium. These ideas prescribe specific detailed functions for the E and H fields and radiant fluxes in the second medium, which help to answer many long standing questions about the physical processes involved in total internal reflection.