The Management of Eutrophicated Waters
67
2.5 Impact of Algal Pollution
There is a direct correlation between the intensity of eutrophication and
algal proliferation. Purification capacity is credited to the algae which
colonize the affected areas according to their own resistance to pollution:
they use. up and accumulate the nutrient surplus together with other
pollutants. However this "beneficient role" ends when the algae are
stranded, or are unable to cope with the degree of pollution, so that they
die and degradation sets in. As the extent of the anaerobic surface grows,
both water and air pollution ensue. The recycling of these nutrients
favors and keeps up entrophication, and can maintain a high biomass
productivity level in an ecosystem on its own.
Houvenaghel and Mathot (1982) in their study of a correlation between decaying biomass, general pollution and algal growth, showed that
algae have economic value as a substrate or additive in methanization, as
fertilizer, as antibiotics, and in food and feed preparation. They pointed
to the anti-eutrophication and concentrator role of U/va. In the Venice
lagoon, collected algae release biogas by mesophilic fermentation,
leading to methane production. Fuel production aids in pollution control
(Croatto 1982).
The impact of algal "pollution" is economic as the very pulse of
numerous affected regions is closely controlled by tourism. Long
"strings" of stranded algae are not only an aesthetic deterrent to use of a
beach, they make access difficult; in addition, hydrogen sulfide produces
a foul odour, and battling algae in the water is not appreciated by
bathers. To provide an idea of the cost of cleaning in- and onshore, the
bill ran to US$ 200000 for 1986 in the Armor region of France. Using the
algal material as fertilizer may clear the beach, but results in stream and
aquifer pollution, as liquefaction juices are loaded with volatile fatty
acids.
More appropriate approaches are biogas extraction, mixing with domestic wastes to produce composts, manufacture of a pre-mix for aviculture, and making an organic-rich soil improver. Nitrogen, phosphorus
and metals can be recycled.
Algal decomposition results in an inversion of the gradient concentration of nutrients in the sediment. Thus man-generated nitrogen and
phosphorus add to the quantities of nutrients resulting from decomposition of algal deposits which keep up the eutrophication condition.
In the Bay of Lannion alone, an additional loss of 500 metric t/year of
sand results as 2000 truck round-trips are necessary to remove the algae.
67
2.5 Impact of Algal Pollution
There is a direct correlation between the intensity of eutrophication and
algal proliferation. Purification capacity is credited to the algae which
colonize the affected areas according to their own resistance to pollution:
they use. up and accumulate the nutrient surplus together with other
pollutants. However this "beneficient role" ends when the algae are
stranded, or are unable to cope with the degree of pollution, so that they
die and degradation sets in. As the extent of the anaerobic surface grows,
both water and air pollution ensue. The recycling of these nutrients
favors and keeps up entrophication, and can maintain a high biomass
productivity level in an ecosystem on its own.
Houvenaghel and Mathot (1982) in their study of a correlation between decaying biomass, general pollution and algal growth, showed that
algae have economic value as a substrate or additive in methanization, as
fertilizer, as antibiotics, and in food and feed preparation. They pointed
to the anti-eutrophication and concentrator role of U/va. In the Venice
lagoon, collected algae release biogas by mesophilic fermentation,
leading to methane production. Fuel production aids in pollution control
(Croatto 1982).
The impact of algal "pollution" is economic as the very pulse of
numerous affected regions is closely controlled by tourism. Long
"strings" of stranded algae are not only an aesthetic deterrent to use of a
beach, they make access difficult; in addition, hydrogen sulfide produces
a foul odour, and battling algae in the water is not appreciated by
bathers. To provide an idea of the cost of cleaning in- and onshore, the
bill ran to US$ 200000 for 1986 in the Armor region of France. Using the
algal material as fertilizer may clear the beach, but results in stream and
aquifer pollution, as liquefaction juices are loaded with volatile fatty
acids.
More appropriate approaches are biogas extraction, mixing with domestic wastes to produce composts, manufacture of a pre-mix for aviculture, and making an organic-rich soil improver. Nitrogen, phosphorus
and metals can be recycled.
Algal decomposition results in an inversion of the gradient concentration of nutrients in the sediment. Thus man-generated nitrogen and
phosphorus add to the quantities of nutrients resulting from decomposition of algal deposits which keep up the eutrophication condition.
In the Bay of Lannion alone, an additional loss of 500 metric t/year of
sand results as 2000 truck round-trips are necessary to remove the algae.