Toilets: Then and Now, Part 08: Excessive Human Wastes in Coastal Waters, Page 1 of 4

(an excess of nutrients flowing from the land to the sea has created serious environment problems)

Many seas and oceans are being excessively "enriched" with human excretions

  • The widespread pollution of Narragansett Bay began with a great celebration on Thanksgiving Day, 1871.
  • The townspeople were giving thanks for the completed construction of their first public water supply.
  • Soon afterward clean water flowed through taps and flush toilets, liberating residents forever from backbreaking trips to the well and freezing visits to the privy.
  • Millions learned the joys of running water between about 1850 and 1920, as towns throughout North America and Europe threw similar parties; but homeowners gave scant thought to how their gleaming new water closets would change the makeup of the oceans.
  • With the wonder of running water came the unpleasant problem of running waste.
  • No longer was human excrement deposited discreetly in dry ground; the new flush toilets discharged streams of polluted water that often flowed through the streets.
  • Town elders coped with the unhappy turn of events by building expensive networks of sewers, which invariably routed waste to the most convenient body of water nearby.
  • In this way, towns quickly succeeded in diverting the torrent of waste from backyards and city streets to fishing spots, swimming holes and adjacent ocean shores.
  • In many cases, the results were disastrous for the aquatic environment; and as the flow continues, society still struggles with the repercussions for the plants and animals that inhabit coastal waters.
  • Uncontrolled Growth

  • Even a century ago the unsightly consequences of dumping raw sewage directly into lakes and bays were quite troubling.
  • Dead fish and malodorous sludges fouled favorite beaches as sewage rode back toward land on the waves. Unwilling to return to the days of chamber pots and privies, people were soon forced to clean up their waste somewhat before discharging it.
  • The wastewater-treatment technologies put into place between about 1880 and 1940 removed visible debris and pathogenic organisms from sewer effluent, effectively eliminating the distasteful reminders that had once washed up on the shore.
  • By the 1960s many treatment plants had begun to remove organic matter as well, but the various methods failed to extract the elements nitrogen and phosphorus, nutrients indispensable to human life and abundant in human waste.
  • These invisible pollutants were flushed into rivers, lakes and oceans in prodigious quantities, and no telltale sign heralded the harm they could inflict.
  • As every farmer and gardener knows, nitrogen and phosphorus are the essential ingredients of plant fertilizers.
  • Plants that live underwater often respond to these nutrients just as beets and roses do: they grow faster.
  • Of course, aquatic plants are different from the trees and shrubs familiar to landlubbers—most are microscopic, single-celled organisms called phytoplankton that drift suspended in the currents.
  • Where nutrients are scarce, phytoplankton are sparse and the water is usually crystalclear.
  • In response to fertilization, phytoplankton multiply explosively, coloring the water shades of green, brown and red with their photosynthetic pigments.
  • These blooms increase the supply of organic matter to aquatic ecosystems, a process known as eutrophication.
  • Pollution-driven eutrophication was not recognized as a serious threat to many larger lakes in Europe and North America until the 1950s and 1960s—Lakes Erie and Washington in the U.S. are well-known examples.
  • Why the accelerating growth of phytoplankton was a concern

  • After all, people welcomed the “green revolution” that fertilizers helped to bring to agriculture around that time.
  • The difference underwater results from the precarious balance between oxygen supply and demand in aquatic ecosystems.
  • Terrestrial ecologists do not usually worry about oxygen, because the air is full of it: each cubic meter contains some 270 grams.
  • And the atmosphere is constantly in motion, replenishing oxygen wherever it is used, but water circulates less readily than air and holds only five to 10 grams of oxygen per cubic meter at best; that is, when freely exchanging its dissolved gases with the atmosphere.
  • Although fish and a number of other aquatic animals have adapted to live under these conditions, a small decrease in the oxygen content of their surroundings can often be deadly to them.
  • Phytoplankton floating near the surface of nutrient-rich lakes fare better in the oxygen equation.
  • They receive ample sunlight to carry out photosynthesis during the day and have access to plenty of oxygen to support their metabolism at night.
  • Even under the best circumstances, phytoplankton are short-lived: the tiny organisms continually die off and sink, leaving new generations growing in their place.
  • The more abundant the bloom, the heavier the fallout to the lower depths.
  • Therein lies the problem: the bottom-living bacteria that digest this dead plant matter consume oxygen.
  • When organic material is abundant in a lake and where surface and bottom waters seldom mix; for example, where winds are calm, oxygen rapidly becomes scarce below the surface.
  • Animals that cannot escape to better-aerated zones will suffocate, and dead creatures may begin to litter the shoreline as bacteria take over the otherwise barren bottom waters.
  • During the 1970s, such awful conditions used to regularly overcome oxygen-starved Lake Erie, which was said to be “dying”.
—Compiled from information located in
"Enriching the Sea to Death" by Scott W. Nixon;
Scientific American, 1998; pages 43-58.

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