Environmental Engineering Reference
In-Depth Information
et al.
1997
; Halling-Sørensen et al.
2000
; Katsumata et al.
2005
,
2006
Kvíderová
and Henley
2005
; Zrimec et al.
2005
; Pan et al.
2009
; Yates and Rogers
2011
),
effect of size-fractionated phytoplankton (Malone
1980
; Chisholm
1992
; Li
1994
;
Tarran et al.
2001
; Hansen and Hjorth
2002
; Stibor and Sommer
2003
; Tittel et al.
2003
; Cermeno et al.
2005
; Unrein et al.
2007
; Zubkov et al.
2007
; Zubkov and
Tarran
2008
), and effects of global warming (Mostofa et al.
2009
; Baulch et al.
2005
; Yates and Rogers
2011
; Morris and Hargreaves
1997
; Cooke et al.
2006
;
Huisman et al.
2006
; Llewellyn
2006
; Richardson
2007
; Malkin et al.
2008
; Prince
et al.
2008
; Davis et al.
2009
; Castle and Rodgers
2009
; Mostofa and Sakugawa
2009
; Etheridge
2010
; Keeling et al.
2010
). These factors have been assessed
in recent studies and are vital to understanding and solving the debate about the
occurrence of photosynthesis in terrestrial plants and aquatic microorganisms.
This chapter will give a general overview on photosynthesis, its key biogeo-
chemical functions, the functions of photosystems (I and II) in organisms during
photosynthesis, and will describe a new hypothesis for photosynthesis that adopts
H
2
O
2
instead of H
2
O. It will also address the debates/questions regarding O
2
release from PSI and PSII during photosynthesis. Finally, it will extensively dis-
cuss the key factors that may significantly influence the photosynthetic activities
of organisms, including higher plants.
2 Photosynthesis in Natural Waters
Photosynthesis is typically defined as a combination of photoinduced and bio-
logical processes that can convert carbon dioxide (CO
2
) and hydrogen peroxide
(H
2
O
2
: photoinduced generation from dissolved oxygen in water) into organic
compounds (e.g. carbohydrates) and O
2
using the sunlight energy. These processes
take place in photosynthetic cells of higher plants, cyanobacteria (or algae) and
bacteria. Carbohydrates are then used for metabolic activities within the cell, and
the whole process is termed as the oxygenic photosynthesis. It should be noted that
cyanobacteria are not bacterial but generally referred to as algae. The chloroplast
pigments of all cyanobacteria and aquatic higher plants have absorption bands in
the blue region of the spectrum, such as the chlorophyll Soret band, and carotenoid
bands (Kirk
1976
). The action spectrum of photosynthesis in green algae, brown
algae, diatoms and euglenas has two broad and intense peaks in the range from
400 to 500 nm of wavelength and in the region from 670 to 700 nm, respectively
(Kirk
1976
; Haxo and Blinks
1950
; Mann and Myers
1968
; Kirk and Reade
1970
;
Iverson and Curl
1973
; Telfer et al.
1990
; Schelvis et al.
1992
; Durrant et al.
1995
;
Renger and Marcus
2002
; Zhang et al.
2009
). Photons of light initiate photosyn-
thesis through releases of electrons across a membrane. It is catalysed by a special
type of membrane-bound pigment-protein complexes called photosynthetic reac-
tion centers (RCs). They are composed of photosystem I (PSI) and photosystem
II (PSII), which will be discussed in the next sections. Oxygenic photosynthe-
sis is caused by cooperation of PSI and PSII RCs and generally occurs in higher
