Environmental Engineering Reference
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the action spectrum. However, the use of multivariate statistical analysis (such as, for
example, principal component analysis) allows to obtain more detailed BWFs.
26,27
The method proposed by Rundel
25
was used to retrieve a biological weighting
function of the UV inhibition of photosynthesis in the green microalga
Dunaliella
salina
, after exposure to simulated solar radiation for 30 minutes.
12
In this work, the combination of two PAR (Photosynthetic Active Radiation)
levels and two UV levels allowed to obtain four different basic radiation regimes: high
UV and high PAR (UVPAR), low UV and high PAR (uvPAR), high UV and low PAR
(UVpar), low UV and low PAR (uvpar). For each of these four regimes ten different
irradiation conditions were applied, ranging from a full simulator spectrum to an almost
complete exclusion of UV radiation. The first was obtained by means of an UV
transparent quartz plate and the others by using various colour filter glasses (WG 295,
WG 305, WG 320, WG 335, WG 345, WG 360, GG 385, GG 400, GG 420). The
inhibition of photosynthesis was evaluated by measuring the chlorophyll fluorescence
parameter, 'F/Fm', which provides a reliable estimate of photosynthetic efficiency.
1.0
UVPAR
UVpar
0.8
uvPAR
uvpar
0.6
0.4
0.2
0.0
Figure 3.
Chlorophyll fluorescence parameter 'F/Fm' measured after the 30 min exposure to the
forty different irradiation conditions of simulated solar radiation (redrawn from reference 12).
A biological weighting function was retrieved from the 40 values of the
fluorescence data (see Fig. 3) assuming that the value P of 'F/Fm' after irradiation
could be calculated by means of the following model function:
P = P
0
[1/(1 + 6H
UV
(O)E
UV
(O)'O + H
PAR
E
PAR
)]
where P
0
is the control value; E
UV
(O) is the spectral photon flux density in the UV and
E
PAR
is the integrated photon flux density in the PAR range; H
UV
(O) and H
PAR
(in
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