Light absorption rate

Illustrative Example 15.2 Using the Screening Factor S(X ) to Estimate the Total Specific Light Absorption Rate ofPNAP in the Epilimnion of... 

Figure 15.9 Graphical representation of the calculation of the near-surface specific light absorption rate, k°, for para-nitro-acetophe-none (PNAP) for a clear-sky midday, midsummer at 40°N latitude. The shaded area corresponds to the total rate. Note that the y axes are on logarithmic scales.

Table 15.5 Calculation of the Near-Surface Total Specific Light Absorption Rate A of p-Nitroacetophenone (PNAP) at 40°N Latitude at Noon on a Clear Midsummer Day...

Figure 15.10 Calculated 24 h averaged near-surface specific light absorption rates, k (24 h), for PNAP as a function of season and latitude in the northern hemisphere (data from Leifer, 1988).

In Table 15.6, the 24 h total specific light absorption rate, (24 h), of PNAP is calculated (estimated) for a clear midsummer day in the well-mixed epilimnion of Greifensee in Switzerland (47°N latitude). For a latitude of 40°N the near-surface total specific light absorption rate k% (noon) of PNAP is calculated for a clear midsummer day in Table 15.5. Can you use this ka (noon) value to estimate kl (24 h) of PNAP in Greifensee If yes, perform the calculation and compare the resulting (24 h) value with the K(24 h) value obtained in Table 15.5. Assume that on a daily basis, a°(noon) is about 2.5 times larger than (24 h) [compare (24 h) given in Fig. 15.10 with (noon) (86400 sd 1)]. 

If we assume that the quantum yield is independent of wavelength, we simply multiply the total specific light absorption rate of the compound in a well-mixed water body by Oir to obtain k. ... 

Estimate the 24 h averaged direct photolysis half-life of 4-nitrophenol (4NP) (a) near the surface, and (b) in the well-mixed epilimnion of Greifensee (pH = 7.5 zmix = 500 cm d(X) values given in Table 15.6) on a clear midsummer day. Furthermore, a friendly colleague has already calculated the 24 h averaged near-surface total specific light absorption rates of the nondissociated (HA) and dissociated (A") species ... 

P 15.3 Estimating the Near-Surface Total Specific Light Absorption Rates of Nitrobenzene... 

In the case of ill-defined photon absorbing volumes such as cloud droplets or arrays of droplet in a well-formed cloud, the specific light absorption rate can be estimated using the following relationship ... 

Radiation model involving multi-lamp reactors is provided by Yokota and Suzuki (22). Based on a diffused line source emission model, the light absorption rate in any geometrical photoreactor with multiple lamps was assessed, and the work reveals the existence of optimum light arrangement. 

T. Yokota and S. Suzuki, Estimation of light absorption rate in a tank type photoreactor with multiple lamps, J. Chem. Eng. Japan 28, 300-305 (1995). 

The light absorption rate of a given chromophore in a water body depends both on the solar spectral irradiance reaching the water surface and on changes in the spectral irradiance as it penetrates down into the water (20, 21). Light absorption and scattering in the stratosphere and troposphere affect... 

TABLE 6.9 Calculation of Near-Surface Specific Light Absorption Rate, for Quinoline at 40° Latitude on a Clear Mid-summer Day... 

Figure 6.8 Graphical presentation of the data in Table 6.9 used to calculate the specific light absorption rate for quinoline at 40° latitude on a clear mid-summer day.

Comoound Half-life (sec) TrlflurallnS Half-life Csecl Experimental Light Intensity (mlcrowatts/cm Light Absorption Rate (photons mole-1 sec l) Quantumh Yield... 

Kandilian R, Pruvost J, Legrand J, Pilon L Influence of light absorption rate by Nannochloropsis oculata on triglyceride production during nitrogen starvation, Bioresour Technol 163 308-319, 2014a. 

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