Environmental Engineering Reference
In-Depth Information
6 Scope of the Future Researches
The mechanisms of the photosynthetic reaction and the changes of the photosyn-
thetic efficiency of organisms are affected by the different factors discussed in this
study. A number of issues may greatly assist to improve the present understand-
ing of photosynthesis. For example, formation of complexes between metal ions
and the functional groups of PSII or PSI is a new suggestion about the processes
that might occur in aquatic environments. Earlier studies did not place much atten-
tion on the complexation theory, which may greatly assist a better understanding
of similar researches. The effects of organic matter (DOM and POM) and of other
factors on photosynthesis are important for understanding the mechanisms of the
release of electrons and O
2
, as well as other vital phenomena. The complexation
theory may provide a better understanding of the molecular basis for the mecha-
nisms of photosystem tolerance to salt or metal ions stress. If proven, such a the-
ory may greatly help the introduction, by plant breeding and genetic engineering,
of salt tolerance in crop plants.
The need for additional studies in photosynthesis can be summarized as fol-
lows: (i) Observations are required of the effects of diverse toxic and non-toxic
organic substances and metals on efficiency of the photosynthesis of various
microorganisms; (ii) The mechanism of relase of O
2
from H
2
O
2
during photosyn-
thesis should be substantiated; (iii) Special attention should be paid to the photo-
systems crystal structure, to find out any presence of H
2
O
2
(or O
2
) instead of H
2
O.
Concurrently, further studies are needed that take special attention during sample
preparation, to avoid the possible decomposition of H
2
O
2
. Such studies would help
solving the debate concerning the process of oxygen release; (iv) A better under-
standing is required of the effect on photosynthesis of exogenous H
2
O
2
, produced
from allochthonous DOM (humic substances including fulvic and humic acids);
(v) The effect of autochthonous DOM (autochthonous fulvic acids of algal/phyto-
plankton origin) on photosynthesis also requires better understanding; (vi) Crystal
structures of PSI or PSII do not include any information about dissolved O
2
, but
they are composed of about 1,300 water molecules (Umena et al.
2011
) and issue
that will need further studies to be clarified. Finally, it is important to remember
during the sample processing of any photosynthesis experiments that H
2
O
2
is rap-
idly decomposed microbilly and it is also rapidly produced under light condition.
7 Nomenclature
CCM
Carbon-concentrating mechanism
Chl
Chlorophyll
CO
2
Carbon dioxide
−
, and CO
3
2
−
DIC
Dissolved inorganic carbon
=
dissolved CO
2
, H
2
CO
3
, HCO
3
DOM
Dissolved organic matter
