9
1 Eutrophication: Challenges and Solutions
ing a trend of freshwater eutrophication worldwide (Bumb
and Baanante 1996).
Phosphorus, an essential nutrient for crop and animal production, can accelerate freshwater eutrophication and is considered as one of the most ubiquitous forms of water quality
impairment in the developed world. Repeated outbreaks of
harmful algal blooms (e.g., Cyanobacteria) have increased
society’s awareness of eutrophication and the need of solutions. Agriculture is regarded as an important source of P in
environment. Specifically, the concentration of specialized
farming systems has led to a transfer of P from areas of grain
production to animal production. This has created regional
surpluses in P inputs (mineral fertilizers and feed) over outputs (crop and animal produce), built up soil P in excess of
crop needs, and increased the loss of P from land to water.
Recent research has shown that this loss of P in both surface
runoff and subsurface flow originates primarily from small
areas within watersheds during a few storms. These areas
occur where high soil P, or P application in mineral fertilizer or manure, coincide with high runoff or erosion potential
(Sharpley et al. 2001).
1.5 Control Measures and Recommendations
Anthropogenic activities are the worst culprit of nutrient enrichment and root cause of eutrophication of water bodies.
Several countries have come forward to address the issue by
implementing a range of technologies, legislative and biological measures.
1.5.1 Biological Control
Phosphorus (P)-induced eutrophication leads to water quality tribulations in aquatic systems, particularly freshwater,
across the globe. Processing of nutrients in shallow habitats
removes P from water naturally. Periphytons are considered
as one of the tools for P removal from the water column in
lotic waters and wetlands. Periphytons play several roles in
removing P from the water column, including P uptake and
deposition and filtering particulate P from the water. Periphyton photosynthesis locally increases pH up to 1 unit, which
can lead to increased precipitation of calcium phosphate,
concurrent deposition of carbonate–phosphate complexes
and long-term burial of P. In general, periphytons tend to increase P retention and deposition (Dodds-Walter 2003).
Nutrients and food webs have been recorded to have
strong interactions which can profoundly alter the eutrophication level of a water body (Hrbâcek et al. 1961; Shapiro
1979; Mazumder 1994; Carpenter et al. 1995; Proulx et al.
1996). The sudden appearance of large populations of herbivorous Daphnia, during the recovery of Lake Washington
from eutrophication, had profound effects on algal biomass
and transparency (Edmondson and Litt 1982; Edmondson
1994). Daphnia are efficient grazers capable of clearing the
water column of edible algal cells, their appearance caused
unexpectedly sharp increase in transparency of Lake Washington (Edmondson 1994).
1.5.1.1 Phytoremediation
In freshwater bodies, the phytoremediation has been suggested to be effective in reducing the toxicity of waters
caused by microorganisms releasing ammonia and sulfide
during degradation of protein released from food industries.
Several plant species have been found to reduce the excess of nitrogen and phosphorus from aquatic system. Aquatic macrophytes such as Eicchornia crassipes and Salvinia
auriculata cause significant reduction of nitrogen and phosphorus compounds in water. This information was felt helpful in developing adequate management strategy for aquatic
macrophytes to check the eutrophication process in Imboassica Lagoon (Petrucio and Esteves 2000). Jiang et al. (2004)
reported that Phragmitis communis and Zizania latifolia have
the efficiency to absorbe N and P and thus these two species
were found to play an important role in the purification of
wetlands receiving nonpoint source pollutants. The harvesting of these species took away 463–515 kg hm
–2
of N and
127–149 kg hm
–2
of P each year. This amount of N and P is
equivalent to the discharge from 2.3–3.2 and 1.3–3.0 hm
–2
of
fields, respectively in this area. The absorption and decomposition capacity of Z. latifolia was higher than P. communis
(Jiang et al. 2004). Abe et al. (2002) investigated nitrate, nitrite, ammonium, and phosphate ions removal characteristics
of aerial macroalga Trentipholia aurea. The 1.5 times higher
biomass was recorded in medium with sufficient N and P
source than in ordinary medium. The macroalga had a potential of 37 % of nitrite and 32 % of nitrate removal from
the wastewater.
Duckweeds have been reported to be promising macrophytes for wastewater treatment. They are used to treat effluent from shrimp farm and found to remove nutrients and
high amounts of ammonia effectively (Ruenglertpanyakul
et al. 2004). The duckweeds increase the degradation of organic material (Sabine et al. 2003).
Cedergreen and Madsen (2004) investigated the ability
and relative contribution of roots and fronds of floating macrophyte Lemna minor for N uptake. They showed that roots
and leaves of L. minor can acquire significant amount of inorganic N through both root and frond.
The wetlands with floating Lemna gibba were constructed to treat wastewater from various sources. The suspended
solid and organic matter removals were the highest. The nitrogen removal increased with higher nitrogen loads. The
phosphorus removal was negligible (Noemi et al. 2004).
1 Eutrophication: Challenges and Solutions
ing a trend of freshwater eutrophication worldwide (Bumb
and Baanante 1996).
Phosphorus, an essential nutrient for crop and animal production, can accelerate freshwater eutrophication and is considered as one of the most ubiquitous forms of water quality
impairment in the developed world. Repeated outbreaks of
harmful algal blooms (e.g., Cyanobacteria) have increased
society’s awareness of eutrophication and the need of solutions. Agriculture is regarded as an important source of P in
environment. Specifically, the concentration of specialized
farming systems has led to a transfer of P from areas of grain
production to animal production. This has created regional
surpluses in P inputs (mineral fertilizers and feed) over outputs (crop and animal produce), built up soil P in excess of
crop needs, and increased the loss of P from land to water.
Recent research has shown that this loss of P in both surface
runoff and subsurface flow originates primarily from small
areas within watersheds during a few storms. These areas
occur where high soil P, or P application in mineral fertilizer or manure, coincide with high runoff or erosion potential
(Sharpley et al. 2001).
1.5 Control Measures and Recommendations
Anthropogenic activities are the worst culprit of nutrient enrichment and root cause of eutrophication of water bodies.
Several countries have come forward to address the issue by
implementing a range of technologies, legislative and biological measures.
1.5.1 Biological Control
Phosphorus (P)-induced eutrophication leads to water quality tribulations in aquatic systems, particularly freshwater,
across the globe. Processing of nutrients in shallow habitats
removes P from water naturally. Periphytons are considered
as one of the tools for P removal from the water column in
lotic waters and wetlands. Periphytons play several roles in
removing P from the water column, including P uptake and
deposition and filtering particulate P from the water. Periphyton photosynthesis locally increases pH up to 1 unit, which
can lead to increased precipitation of calcium phosphate,
concurrent deposition of carbonate–phosphate complexes
and long-term burial of P. In general, periphytons tend to increase P retention and deposition (Dodds-Walter 2003).
Nutrients and food webs have been recorded to have
strong interactions which can profoundly alter the eutrophication level of a water body (Hrbâcek et al. 1961; Shapiro
1979; Mazumder 1994; Carpenter et al. 1995; Proulx et al.
1996). The sudden appearance of large populations of herbivorous Daphnia, during the recovery of Lake Washington
from eutrophication, had profound effects on algal biomass
and transparency (Edmondson and Litt 1982; Edmondson
1994). Daphnia are efficient grazers capable of clearing the
water column of edible algal cells, their appearance caused
unexpectedly sharp increase in transparency of Lake Washington (Edmondson 1994).
1.5.1.1 Phytoremediation
In freshwater bodies, the phytoremediation has been suggested to be effective in reducing the toxicity of waters
caused by microorganisms releasing ammonia and sulfide
during degradation of protein released from food industries.
Several plant species have been found to reduce the excess of nitrogen and phosphorus from aquatic system. Aquatic macrophytes such as Eicchornia crassipes and Salvinia
auriculata cause significant reduction of nitrogen and phosphorus compounds in water. This information was felt helpful in developing adequate management strategy for aquatic
macrophytes to check the eutrophication process in Imboassica Lagoon (Petrucio and Esteves 2000). Jiang et al. (2004)
reported that Phragmitis communis and Zizania latifolia have
the efficiency to absorbe N and P and thus these two species
were found to play an important role in the purification of
wetlands receiving nonpoint source pollutants. The harvesting of these species took away 463–515 kg hm
–2
of N and
127–149 kg hm
–2
of P each year. This amount of N and P is
equivalent to the discharge from 2.3–3.2 and 1.3–3.0 hm
–2
of
fields, respectively in this area. The absorption and decomposition capacity of Z. latifolia was higher than P. communis
(Jiang et al. 2004). Abe et al. (2002) investigated nitrate, nitrite, ammonium, and phosphate ions removal characteristics
of aerial macroalga Trentipholia aurea. The 1.5 times higher
biomass was recorded in medium with sufficient N and P
source than in ordinary medium. The macroalga had a potential of 37 % of nitrite and 32 % of nitrate removal from
the wastewater.
Duckweeds have been reported to be promising macrophytes for wastewater treatment. They are used to treat effluent from shrimp farm and found to remove nutrients and
high amounts of ammonia effectively (Ruenglertpanyakul
et al. 2004). The duckweeds increase the degradation of organic material (Sabine et al. 2003).
Cedergreen and Madsen (2004) investigated the ability
and relative contribution of roots and fronds of floating macrophyte Lemna minor for N uptake. They showed that roots
and leaves of L. minor can acquire significant amount of inorganic N through both root and frond.
The wetlands with floating Lemna gibba were constructed to treat wastewater from various sources. The suspended
solid and organic matter removals were the highest. The nitrogen removal increased with higher nitrogen loads. The
phosphorus removal was negligible (Noemi et al. 2004).