232
M. Naeem et al.
affected by precipitation and dissolution of calcium carbonates and the production and destruction of phytoplankton.
Measurements of pH are also important in understanding the
dynamic nature of biogeochemical processes and the state
of all the acid-base systems present in the water. The eutrophication-induced phytoplankton bloom, hence the intensive
photosynthesis, can locally decrease the pCO 2 and increase
the pH. The precipitation of calcium carbonate may occur at
this high pH in seawater already supersaturated with respect
to calcium carbonate (Berner and Morse 1974). The precipitation of calcium carbonate has been reported to be triggered
by phytoplankton blooms in some shallow lakes. This suggests that the precipitation of calcium carbonate, caused by
phytoplankton blooms, may play an important role in the
cycling and transport of nutrients in water bodies through
adsorption and coprecipitation of nutrient compounds (e.g.,
PO 4
3− and NH 4
+ ) on the suspended matter. Studies are
needed to examine how the inorganic formation of calcium
carbonate can control the fate of nutrients in water bodies
produced by anthropogenic activities. The model would require the knowledge of partitioning of phosphorus between
different reservoirs, such as a water column, suspended matter, and sediment; the speciation of phosphorus in each reservoir (organic and inorganic phosphorus) and their biological
availability; the influence of pCO 2 , total CO 2 , pH, salinity,
temperature, and other environmental factors on the phosphorus transformation between different reservoirs (Burton
and Walter 1990).
16.4.8 Sources and Functions of Magnesium
Magnesium (Mg) is available to plants as the magnesium ion
(Mg
2+
). The predominant role of Mg is as a major constituent of the chlorophyll molecule, and it is therefore actively
involved in photosynthesis. Mg is a cofactor in several enzymatic reactions that activate the phosphorylation processes.
Mg is required to stabilize ribosome particles and also helps
stabilize the structure of nucleic acids. Mg also assists the
movement of sugars within a plant (Uchida 2000; Marschner
2002).
16.4.9 Role of Magnesium in Eutrophication
Magnesium is often associated with calcium in all kinds of
waters, but its concentration remains generally lower than the
calcium (Venkatasubramani and Meenambal 2007). Magnesium is essential for chlorophyll synthesis and acts as a limiting factor for the growth of phytoplankton (Dagaonkar and
Saksena 1992). Therefore, depletion of magnesium reduces
the phytoplankton population. Dwivedi et al. (2000) recorded magnesium content up to 3.27 mg L
−1
in Naktara reservoir. In the present investigation, the magnesium content up
to 5.60 mg L
−1
was observed with higher concentration during winter season and lower concentration in monsoon season. At neutral to alkaline pH, magnesium ions are capable
to restrict the tendency to precipitate of phosphorus (Stratful
et al. 2001). Being the essential element, magnesium often
limits the growth of primary producers such as algae, other
aquatic plants, cyanobacteria, photosynthetic bacteria. Some
heterotrophic microorganisms are also capable of solubilizing phosphates combined with calcium or magnesium (Atlas
and Bartha 1998). These soluble forms can be readily taken
up by plants, algae, cyanobacteria, and autotrophic bacteria
and is assimilated into organic cellular components (DNA,
RNA, ATP).
16.4.10 Sources and Functions of Copper
Copper (Cu) is available to plants as copper ion (Cu
++
). Cu
is essential in several plant enzyme systems involved in photosynthesis. Cu is part of the chloroplast-protein plastocyanin, which forms part of the electron transport chain. Cu may
have a role in the synthesis and/or stability of chlorophyll
and other plant pigments (Uchida 2000; Marschner 2002).
16.4.11 Role of Copper in Eutrophication
Copper is a phytotoxic heavy metal (Rai et al. 1981) and it
inhibits the photosynthesis and growth of algae at low concentrations (Garvey et al. 1991). Plant communities grown
in high phosphate concentrations were more tolerant to copper than the ones grown in lower phosphate concentrations
(Guasch et al. 2002). An increase in the tolerance to copper
was also observed after phosphorus addition in the soil with
low phosphate concentrations (Guasch et al. 2002). Several
arguments have been proposed in order to understand the
interaction between phosphorus availability and copper toxicity. In general, biofilm-matrix plays an important role in
metal tolerance, as the biofilm-matrix can have a protective
function by limiting the penetration of metals (Barranguet
et al. 2002; Guasch et al. 2003). It has been suggested that
Cu induces the deficiency of P (Nalewajko and Olaveson
1994). Communities growing with higher P availability may
be more tolerant to copper owing to the possible formation
of polyphosphate bodies that can complex the copper and
detoxify the cells (Hall et al. 1989). Copper toxicity in natural periphyton communities depends on phosphorus availability (Guasch et al. 2004). Verma et al. (1993) evidenced
that Cu toxicity in cyanobacteria was owing to Cu-induced
phosphate starvation and that the exogenous addition of
phosphate could antagonize the Cu-effect in Nostoc calcicola. It has been reported that Cu induces the deficiency of P
M. Naeem et al.
affected by precipitation and dissolution of calcium carbonates and the production and destruction of phytoplankton.
Measurements of pH are also important in understanding the
dynamic nature of biogeochemical processes and the state
of all the acid-base systems present in the water. The eutrophication-induced phytoplankton bloom, hence the intensive
photosynthesis, can locally decrease the pCO 2 and increase
the pH. The precipitation of calcium carbonate may occur at
this high pH in seawater already supersaturated with respect
to calcium carbonate (Berner and Morse 1974). The precipitation of calcium carbonate has been reported to be triggered
by phytoplankton blooms in some shallow lakes. This suggests that the precipitation of calcium carbonate, caused by
phytoplankton blooms, may play an important role in the
cycling and transport of nutrients in water bodies through
adsorption and coprecipitation of nutrient compounds (e.g.,
PO 4
3− and NH 4
+ ) on the suspended matter. Studies are
needed to examine how the inorganic formation of calcium
carbonate can control the fate of nutrients in water bodies
produced by anthropogenic activities. The model would require the knowledge of partitioning of phosphorus between
different reservoirs, such as a water column, suspended matter, and sediment; the speciation of phosphorus in each reservoir (organic and inorganic phosphorus) and their biological
availability; the influence of pCO 2 , total CO 2 , pH, salinity,
temperature, and other environmental factors on the phosphorus transformation between different reservoirs (Burton
and Walter 1990).
16.4.8 Sources and Functions of Magnesium
Magnesium (Mg) is available to plants as the magnesium ion
(Mg
2+
). The predominant role of Mg is as a major constituent of the chlorophyll molecule, and it is therefore actively
involved in photosynthesis. Mg is a cofactor in several enzymatic reactions that activate the phosphorylation processes.
Mg is required to stabilize ribosome particles and also helps
stabilize the structure of nucleic acids. Mg also assists the
movement of sugars within a plant (Uchida 2000; Marschner
2002).
16.4.9 Role of Magnesium in Eutrophication
Magnesium is often associated with calcium in all kinds of
waters, but its concentration remains generally lower than the
calcium (Venkatasubramani and Meenambal 2007). Magnesium is essential for chlorophyll synthesis and acts as a limiting factor for the growth of phytoplankton (Dagaonkar and
Saksena 1992). Therefore, depletion of magnesium reduces
the phytoplankton population. Dwivedi et al. (2000) recorded magnesium content up to 3.27 mg L
−1
in Naktara reservoir. In the present investigation, the magnesium content up
to 5.60 mg L
−1
was observed with higher concentration during winter season and lower concentration in monsoon season. At neutral to alkaline pH, magnesium ions are capable
to restrict the tendency to precipitate of phosphorus (Stratful
et al. 2001). Being the essential element, magnesium often
limits the growth of primary producers such as algae, other
aquatic plants, cyanobacteria, photosynthetic bacteria. Some
heterotrophic microorganisms are also capable of solubilizing phosphates combined with calcium or magnesium (Atlas
and Bartha 1998). These soluble forms can be readily taken
up by plants, algae, cyanobacteria, and autotrophic bacteria
and is assimilated into organic cellular components (DNA,
RNA, ATP).
16.4.10 Sources and Functions of Copper
Copper (Cu) is available to plants as copper ion (Cu
++
). Cu
is essential in several plant enzyme systems involved in photosynthesis. Cu is part of the chloroplast-protein plastocyanin, which forms part of the electron transport chain. Cu may
have a role in the synthesis and/or stability of chlorophyll
and other plant pigments (Uchida 2000; Marschner 2002).
16.4.11 Role of Copper in Eutrophication
Copper is a phytotoxic heavy metal (Rai et al. 1981) and it
inhibits the photosynthesis and growth of algae at low concentrations (Garvey et al. 1991). Plant communities grown
in high phosphate concentrations were more tolerant to copper than the ones grown in lower phosphate concentrations
(Guasch et al. 2002). An increase in the tolerance to copper
was also observed after phosphorus addition in the soil with
low phosphate concentrations (Guasch et al. 2002). Several
arguments have been proposed in order to understand the
interaction between phosphorus availability and copper toxicity. In general, biofilm-matrix plays an important role in
metal tolerance, as the biofilm-matrix can have a protective
function by limiting the penetration of metals (Barranguet
et al. 2002; Guasch et al. 2003). It has been suggested that
Cu induces the deficiency of P (Nalewajko and Olaveson
1994). Communities growing with higher P availability may
be more tolerant to copper owing to the possible formation
of polyphosphate bodies that can complex the copper and
detoxify the cells (Hall et al. 1989). Copper toxicity in natural periphyton communities depends on phosphorus availability (Guasch et al. 2004). Verma et al. (1993) evidenced
that Cu toxicity in cyanobacteria was owing to Cu-induced
phosphate starvation and that the exogenous addition of
phosphate could antagonize the Cu-effect in Nostoc calcicola. It has been reported that Cu induces the deficiency of P