Movement of Light, Heat, and Chemicals in Water Chapter 3 Movement of Light, Heat, and Chemicals in Water Dodds & Whiles ©2010 Elsevier, Inc.

the middle of each agar plate is labeled. FIGURE 3.1 Diffusion of dye into a 0.5% agar solution in 10 cm diameter petri dishes as a function of time. The agar prevents turbulent mixing so the outward spread of the dye is indicative of the rate of molecular diffusion. Length of time since dye was added to a small depression in the middle of each agar plate is labeled. ©2010 Elsevier, Inc.

FIGURE 3.2 Schematic illustrating diffusion between two flat surfaces at different concentrations (C1 and C2). The rate of diffusion (J) is described by Fick’s law (see text). The concentration at C1 is greater than at C2, so the net diffusion is toward C2. Diffusion is less rapid as distance (x1 2 x2) between the two planes increases and as the difference between the concentrations at the two planes (C1 2 C2) decreases. ©2010 Elsevier, Inc.

Effect of temperature on rate of diffusion of chloride. FIGURE 3.3 Effect of temperature on rate of diffusion of chloride. ©2010 Elsevier, Inc.

FIGURE 3.4 Spectral energy distribution of solar radiation outside the Earth’s atmosphere and inside the atmosphere at sea level. Note how the atmosphere changes the spectral distribution of light. (After Air Force, 1960). ©2010 Elsevier, Inc.

absorbed in the water column. FIGURE 3.5 Schematic of light entering water, where it can be reflected back, scatter off of a particle, or be absorbed in the water column. ©2010 Elsevier, Inc.

FIGURE 3.6 Light as a function of depth in three lakes—Waldo Lake (oligotrophic), Triangle Lake (mesotrophic), and a sewage oxidation pond (eutrophic), Oregon—plotted on linear (A) and log (B) scales. (R. W. Castenholz, unpublished data). ©2010 Elsevier, Inc.

FIGURE 3.7 Secchi depth as a function of extinction coefficient (measured with a quantum meter, 400–700 nm) for 13 Oregon lakes. Boundaries between trophic states for Secchi depth set according to the classification of OECD (1982). (R. W. Castenholz, unpublished data). ©2010 Elsevier, Inc.

FIGURE 3.8 The absorption (A) and transmission (B) of light by pure water as a function of wavelength of light. (Data from Kirk, 1994). ©2010 Elsevier, Inc.

FIGURE 3.9 Light transmission as a function of color for an oligotrophic lake (Waldo Lake, 1984; A), a mesotrophic lake (Munsel Lake, 1984; B), and a eutrophic lake (Siltcoos Lake, 1983; C) in Oregon. (R. W. Castenholz, unpublished data). ©2010 Elsevier, Inc.

FIGURE 3.10 Profiles of chlorophyll a concentration and light with depth at Pottawatomie State Fishing Lake No. 2, Kansas. Deep chlorophyll peaks are attributable to the presence of large populations of cyanobacteria (Oscillatoria). The high biomass of algae occurs in a region with 1–0.001% of surface sunlight. Note how the attenuation of light increases (shallower slope of the light curve) because of the dense algal populations. ©2010 Elsevier, Inc.