Environmental Engineering Reference
In-Depth Information
of ROOH compounds and their concentrations in natural waters. Investigations
based on the detection of ROOH would be crucial to improve the understand-
ing of the photoinduced processes along with H
2
O
2
generation in natural waters.
Limited attention is also devoted to what fractions of DOM are most involved
in the photoinduced production of peroxides in freshwater and marine environ-
ments. Other important research demands for future challenges are the following:
(i) Identification of the DOM components involved into the production of H
2
O
2
in
freshwater and marine water. (ii) Elucidation of the temperature and pH effect on
the production of H
2
O
2
and ROOH compounds by aquatic DOM components and
standard organic substances. (iii) Clarification of the correlation between diurnal
variations of H
2
O
2
and ROOH levels in natural waters and DOM concentration.
(iv) Investigation of the role of the photo-Fenton reaction in the production of per-
oxides in iron-rich waters. (v) Elucidation of the relationship between peroxides
and free radicals. (vi) Study of the dark production of H
2
O
2
and ROOH by phy-
toplankton, algae and bacteria in fresh and marine waters. (vii) Effect of variable
diurnal levels of H
2
O
2
on bacteria in DOM-rich waters. (viii) Detection of ROOH
compounds generated photochemically by standard organic substances in aqueous
solution and by DOM components in natural waters.
Problems
(1) Explain the nature and biogeochemical function of H
2
O
2
and ROOH in natu-
ral waters.
(2) Discuss the steady-state concentration of H
2
O
2
and ROOH in natural waters
(3) Explain how H
2
O
2
acts as REDOX agent.
(4) Explain the mechanisms of photoinduced generation of H
2
O
2
and ROOH in
the gas phase and in natural waters.
(5) How does fulvic acid photolytically produce H
2
O
2
and ROOH in natural
waters?
(6) What are the sources of H
2
O
2
in natural waters?
(7) What factors are involved in the diurnal cycle of H
2
O
2
production in natural
waters?
(8) Explain the controlling factors for the decay of H
2
O
2
and its decay mecha-
nism by biological processes in natural waters.
(9) What is the importance of H
2
O
2
and ROOH?
(10) Which is the impact of H
2
O
2
on organisms?
(11) What is the link between H
2
O
2
, photosynthesis and the autochthonous pro-
duction of DOM in natural waters?
(12) How does H
2
O
2
differ chemically from ROOH?
(13) What is the principle of H
2
O
2
and ROOH measurement by the fluorometric
method?
(14) In a diurnal cycle in river water, the concentration of H
2
O
2
gradually
increased from 4 to 69 nM in the period from before sunrise to noon and
