10. Culltural04
-
Upload
enzo-taping -
Category
Documents
-
view
218 -
download
0
Transcript of 10. Culltural04
7/31/2019 10. Culltural04
http://slidepdf.com/reader/full/10-culltural04 1/31
Lake ClassificationandCultural Eutrophication
1) How are lakes classified in regards to trophicstatus?
2) What is cultural eutrophication?
3) What are the success stories and continuingproblems of cultural eutrophication?
7/31/2019 10. Culltural04
http://slidepdf.com/reader/full/10-culltural04 2/31
Originally, lakes were classified as either oligotrophicor eutrophic, unless they were dystrophic—browncolored water due to dissolved humic substances
(tannins)
We have already talked about
oligotrophic vs. eutrophic
clear vs. green
orthograde vs. clinograde
7/31/2019 10. Culltural04
http://slidepdf.com/reader/full/10-culltural04 3/31
Ultraoligotrophic <5 ug/lOligotrophic 5-10 ug/lMesotrophic 10-30 ug/lEutrophic 30-100 ug/lHypereutrophic > 100 ug/l
Now classify lakes and their productivity based on TPduring spring circulation
http://resac.gis.umn.edu/lakeweb/wquality.htm
7/31/2019 10. Culltural04
http://slidepdf.com/reader/full/10-culltural04 4/31
Originally thought that lakes were all createdoligotrophic, but became eutrophic over time
Thought there was a natural ontongeny to lakes
Less productive
More productive
7/31/2019 10. Culltural04
http://slidepdf.com/reader/full/10-culltural04 5/31
Productivity strongly related to basin morphometry.
This progress through trophic states may be true forsome lakes, but some lakes were “born” productive.
August Thienemann (1882-1960) compared the ratioof the volume of the epilimnion to the volume of the
hypolimnion
epi/hypo < 1
oligotrophic
epi/hypo >1
eutrophic
7/31/2019 10. Culltural04
http://slidepdf.com/reader/full/10-culltural04 6/31
Cultural Eutrophication —increases in phytoplanktondue to human-induced increases in nutrient (P) input
But, humans alter lake productivity
By the late 1800s, and early part of the 1900s, itbecame clear that some lakes were becomingeutrophic much faster than was predicted
Lakes that had historically been clear were gettingdense blooms of blue-green algae and fish were dying
7/31/2019 10. Culltural04
http://slidepdf.com/reader/full/10-culltural04 7/31
This was happing to several large lakes
Lake Zurich, Switzerland Lake Constance, Germany
Lake Erie
europeforvisitors.com
7/31/2019 10. Culltural04
http://slidepdf.com/reader/full/10-culltural04 8/31
Dilution was thought to be thebest solution for wastes
Chicago Ship and Sanitary Canalreversed the flow of the
Chicago River
Chicago originally pumped itsraw sewage into Lake Michigan
Why was this happening???
7/31/2019 10. Culltural04
http://slidepdf.com/reader/full/10-culltural04 9/31
Why was this happening???
Both human waste and early
synthetic detergents(prevalent after WWII) werehigh in phosphorous
But in the 1960s, the limiting nutrient for algalgrowth was still a subject of debate
Most lakes are P limited, add
more P, increase algal growth
7/31/2019 10. Culltural04
http://slidepdf.com/reader/full/10-culltural04 10/31
Detergent industry argued that there was noevidence that excess P was harmful to lakes
This argument was far from being just academic,lots of money involved (taxpayers, municipalities,industry)
In 1960s and 1970s, huge debates over whatlimited algal growth—some said P, others N,
others C (CO2)
7/31/2019 10. Culltural04
http://slidepdf.com/reader/full/10-culltural04 11/31
Why phosphates in detergent?• softens the water• aids in cleaning
• keeps dirt particles in suspension
Developing alternatives was expensivefor the detergent industry
Took until 1994 to be eliminated
from most major laundry detergents(but still common in detergents forautomatic dishwashers)
7/31/2019 10. Culltural04
http://slidepdf.com/reader/full/10-culltural04 12/31
ELA Lake 226
D. Schindler 1974
7/31/2019 10. Culltural04
http://slidepdf.com/reader/full/10-culltural04 13/31
The LakeWashingtonStory—An Urban
Lake
Edmondson 1991The Uses of Ecology: Lake
Washington and Beyond
7/31/2019 10. Culltural04
http://slidepdf.com/reader/full/10-culltural04 14/31
Primary sewage treatment -- removes solidmaterial by filtering and settling.
Does not
removedissolvedmaterial
(nutrients)
7/31/2019 10. Culltural04
http://slidepdf.com/reader/full/10-culltural04 15/31
Secondary sewage treatment-- removesthe dissolved organic material.
Bacteria andothermicroorganismsconsume thedissolvedorganic
material
Does not remove the dissolved inorganicnutrients
7/31/2019 10. Culltural04
http://slidepdf.com/reader/full/10-culltural04 16/31
Tertiary sewage treatment--The final, mostcostly (and often not completed) stage in
sewage treatment
Removesphosphates
and nitratesfrom thewater
L k W h b l h l k
7/31/2019 10. Culltural04
http://slidepdf.com/reader/full/10-culltural04 17/31
1922 30 outfalls took sewage into Lake Washington
Lake Washington began as an oligotrophic lake
1851 The settlement that would become Seattle wasfounded
1883 The Seattle Sewerage agency constructed aseries of pipes to pump raw sewage out into the lake(outfalls) (this was a problem because most peoplestill got their drinking water from the lake)
1936 A i l di i l d
7/31/2019 10. Culltural04
http://slidepdf.com/reader/full/10-culltural04 18/31
1941 Secondary Sewage Treatment plants installed
1936 A partial diversion system was completed totake the raw sewage into Puget Sound (From 1956-1966, 70 million gallons per day of raw sewage was
pumped into Puget Sound).
This diversion was just for the outfalls that were
closest to Puget Sound. Which, at that time, wasmost of the people, but as Seattle expanded, sodid the sewage problem
7/31/2019 10. Culltural04
http://slidepdf.com/reader/full/10-culltural04 19/31
1955 G C A d t PhD d t
7/31/2019 10. Culltural04
http://slidepdf.com/reader/full/10-culltural04 20/31
Algae is Oscillatoria rubescens , a blue-green that
had been forming denseblooms in Lake Zurich.
1955 George C. Anderson, a recent PhD graduatefrom the University of Washington goes sailing.
Brings back a beer bottle full of algae to TommyEdmondson
www.ucmp.berkeley.edu/bacteria/ oscillatoria2.jpg
7/31/2019 10. Culltural04
http://slidepdf.com/reader/full/10-culltural04 21/31
Changes cost money:
1. To industry, which ispasses along to theconsumer
2. To the taxpayer
Public action can make
a difference
Edmondson recognizedthe problem andargued for diversion
1958 P bli t f
7/31/2019 10. Culltural04
http://slidepdf.com/reader/full/10-culltural04 22/31
1976 Recordtransparencies—Hugeincreases in Daphnia populations
1958 Public vote fortotal diversion of sewagefrom Lake Washington
1968 Total Diversion
7/31/2019 10. Culltural04
http://slidepdf.com/reader/full/10-culltural04 23/31
Wh did D h i i ?
7/31/2019 10. Culltural04
http://slidepdf.com/reader/full/10-culltural04 24/31
Why did Daphnia increase?
Oscillatoria interferes with Daphnia feeding, so
fewer Daphnia during peak eutrophication
Prior to eutrophication, Daphnia had traditionally
suffered heavy predation pressure by Neomysis ,www.delta.dfg.ca.gov/ baydelta/neompic.gif
Where did all the
Neomysis go?
Wh did ll th N m sis ?
7/31/2019 10. Culltural04
http://slidepdf.com/reader/full/10-culltural04 25/31
Where did all the Neomysis go?
Neomysis are a preferred prey for juvenile longfin
smelt
dnr.metrokc.gov/wlr/waterres/ lakes/fishmort.jpg
Reasons for smeltincrease are notobvious, but maybe linked to
improvements inbreeding habitat inthe Cedar River
7/31/2019 10. Culltural04
http://slidepdf.com/reader/full/10-culltural04 26/31
But, not all lakes recover this quickly, often due tointernal loading or lack of success with top-down
control
Lake Washington recovered as a result of both
bottom-up control (reduced nutrients) and topdown control (reduced predation on the grazers)
7/31/2019 10. Culltural04
http://slidepdf.com/reader/full/10-culltural04 27/31
Good Professor Edmondson(to the tune of “Good King Wenceslaus”)
Good Professor Edmondson looked outside one nooning,Looked out on Lake Washington, noticed it was blooming.All the other scientists asked what was polluting.Some said it was CO2; he said it was soo-oo-age.
The lake had turned a muddy brown from Oscillatoria,
Reminded of Lake Zurich, then, he was in euphoria.All of the Seattleites looked on with aversion.They believed their lake was dead, he called for diver-er-sion.
Voters took a public stand to make their lake look pretty.
Their task began in ’63; it ended with Lake City. They harkened to his learned words, pollution dropped to zero.Good Professor Edmondson had become a he-ee-ro.
By J.T. Lehman
Cultural eutrophication is still a problem
7/31/2019 10. Culltural04
http://slidepdf.com/reader/full/10-culltural04 28/31
Cultural eutrophication is still a problem
Mandatory sewage treatment and diversion (mostly)solved the problem of point-source pollution
Now cultural eutrophication is often caused by non- point source pollution
Use of fertilizer, changes in land use and climatechange interact to create new problems
Lake Tahoe Hatch et al 2001
7/31/2019 10. Culltural04
http://slidepdf.com/reader/full/10-culltural04 29/31
Lake Tahoe Hatch et al. 2001
Human impact began to increaseafter the 1960 Winter Olympicsat Squaw Valley
https://reader009.{domain}/reader009/html5/0427/5ae206fcb47d3
http://www.ilec.or.jp/database/nam/NAM02-01.gif Since 1968, transparency (Secchidepth) has declined by about 30cm/year
Streams are brining anincreasing amount of PP into the
lake after snowmelt
7/31/2019 10. Culltural04
http://slidepdf.com/reader/full/10-culltural04 30/31
Concepts to know
Is there a natural ontongeny to lakes?
What happened in Lake Washington?
Lake Erie and Lake Washington are twoexamples of lakes that were “saved”. Willall lakes respond to diversion? Why orwhy not?
Do we still need to worry about culturaleutrophication?
7/31/2019 10. Culltural04
http://slidepdf.com/reader/full/10-culltural04 31/31
Practice question
It is well established that many lakes in industrializedregions have experienced cultural eutrophication,primarily as the result of sewage pollution. Lake
Washington, USA, serves as a dramatic example of howdiversion of that sewage (and subsequent reduction inphosphorus pollution) can restore lake clarity. In otherlakes, however, reversal of the effect of phosphoruspollution has been slow to appear, primarily due to
internal loading. Please explain the process of internalloading, including a consideration of what types of lakesare most likely to be influenced by internal loading, andwhy it can slow down lake recovery from sewage pollution.