Environmental Engineering Reference
In-Depth Information
Fig. 7.2 Global average
temperature and carbon
dioxide concentrations
acidi
cation because it directly impacts their
blood oxygen transport and respiration (Portner
et al. 2005 ). Sea urchins raised in lower-pH
waters show evidence for inhibited growth due to
their inability to maintain internal acid-base bal-
ance (Kurihara and Shirayama 2004 ). Scientists
have also seen a reduced ability of marine algae
and animals to produce protective carbonate
shells (Gattuso et al. 1998 ; Langdon et al. 2000 ;
Riebesell et al. 2000 ). These organisms are
important food sources for many marine species.
One such example is a pteropod, a free-swim-
ming molluscan species that is eaten by organ-
isms ranging in size from tiny zooplankton to
whales. In particular, pteropods are an important
source
a positive impact on coastal vegetation, but on
the other hand may pose an adverse impact on
shell forming organisms by triggering the pro-
cess of ocean acidi
cation.
C. Volcanic Activities
Volcanic eruptions are major natural distur-
bances with varied and complex consequences.
Apart from generation of ash particles, volcanic
activities also alter the surrounding water chem-
istry to a great extent. This can cause consider-
able impact on coastal vegetation and more
preferably on phytoplankton. The volcanic
activity of Barren Island is found to have con-
siderable impact in chemical wet depositions
occurred due to rainwater at Port Blair. It also
appears to be a causative factor for higher sul-
phate and nitrate and the lower-pH values of the
ambient aquatic phase. After the
c juvenile salmon.
Mackerel, Pollock, herring and cod are also
known to feed on pteropods. Many species of
other marine calci
for North Paci
rst eruption
noticed in April 1991 began with hot gases and
strong ash emissions with activity continuing
through October, another eruption was noticed in
December 1994 and January
ers, such as coccolithophores
(microscopic algae), foraminifera (microscopic
protozoans), coralline algae (benthic algae),
echinoderms (sea urchins and star
sh) and mol-
luscs (snails, clams and squid) also exhibit a
general decline in their ability to produce shells
with decreasing pH (Kleypas et al. 2006 ). A very
recent study conducted by the present authors
exhibits signi
March 1995, where
thick clouds of pale brownish gas, dark ash
particles and white steam were observed. Very
high values of sulphate ion concentrations in
rainwater were observed from January to April in
1995 when predominant winds are northeasterly.
The volcanic emission of smoke was also
reported during January 2000. The pH values
showed a decreasing sulphate and nitrate con-
centrations exhibited an increasing tendency
from the year 1995 onwards. As the volcanic
eruption at Barren Island during 1991 almost
-
cant inverse relationship between
aquatic pH and shell weight of
Saccostrea cu-
cullata
in Indian Sundarbans estuarine water.
The detailed study along with the results and
interpretations are discussed in Chap. 6 . Thus, in
conclusion, it can be advocated that increase of
atmospheric carbon dioxide may one-way cause
 
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