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UNCE, Reno, NV
Nutrients Phosphorus
Nitrogen
The biggest concern with excess nutrients The biggest concern with excess nutrients is eutrophicationis eutrophication
Results in:
• impacts on lake/stream ecology webs;
• toxins;
• drinking water treatment problems;
• other changes in lake chemistry
Dead plants decay Dead plants decay
Excess nutrients Excess nutrients
Excess aquatic plants Excess aquatic plants
Fish killsFish kills
Low dissolved Low dissolved oxygen oxygen
Freshwater Life Image Archive
Plants require Oxygen, Carbon, Nitrogen and Phosphorus in a fixed ratio
212 : 106 : 16 : 1 (by molarity –eg moles/liter)
109 : 41 : 7.2 : 1 (by weight- eg mg / liter)
Redfield Ratio
Nutrient Limitation
Typically N or P is “limiting” to aquatic plant production (not present at Redfield ratio)
Adding more of the limiting nutrient increased biological production until another nutrient or other factor limits growth
212 : 106 : 16 : 1 (by atoms)
109 : 41 : 7.2 : 1 (by weight)
To determine limiting nutrient
measure the ratio of N:P in a water body and compare to Redfield ratio
16 : 1 (by atoms) = molar ratio
7.2 : 1 (by weight)
Ratios of Total N to Total P < 10 (by weight)
=> N limits algal growth Ratios > 20 (by weight)
=> P limits algal growth
Ratios in between – “co-limitation” – response hard to predict
Why focus on phosphorus?
“Traditional” view (which many question):Phosphorus assumed to be limiting in many pristine waters in mid-latitudes
Many studies have demonstrated relationship between phosphorus loading to lakes and increased algae
Practical view (which fewer question):
In many cases, reducing phosphorus reduces algae
Phosphorus removal much more feasible and less expensive
Phosphorus Cycle
Natural phosphorus sources:
Terrestrial rocks
Marine sediments
Sediment
Guano
Organic material
Atmospheric deposition
Human phosphorus sources
(often more biologically available)
Sediment
(agriculture, logging, construction)
Fertilizers
Animal waste
Septic tanks
Wastewater treatment
Aquatic phosphorus cycle:
Animal tissue
Plant tissue
Water:Dissolved inorganic P
(DIP)
Dissolved /ParticulateOrganic P
(POP, DOP)
Bacterial tissue
Lake Sediment
Phosphate-bearing rock
Phosphorus in water occurs in many mineral forms and in biological material
Dissolved total phosphorus • inorganic + organic
Orthophosphate (orthophosphate = PO4)• inorganic
Total phosphorus = all phosphorus in water• dissolved and particulate, inorganic and organic
Dissolved Total Phosphorus
Filter the sample in the field, test for total P in filtered sample
Total Particulate Phosphorus
Subtract that amountfrom total P
Dissolved (< .45 um):• Phosphate ions (PO4)• Organic molecules• Other?
Particulate (> .45 um):• Mineral• Organic
Total Phosphorus (TP) = all phosphorus in the field sample
(“digest” entire sample)
Inorganic P:digest awayorganic phosphorus, test the remaining sample
Organic P:subtract Inorganic Pfrom total
Organic:• phosphorus incorporated into plant or animal materials• phosphorus in organic molecules
Inorganic:• mineral forms• phosphate ions (PO4)• poly-phosphates
Phosphorus can also be divided into organic and inorganic fractions
Phosphorus forms source, transport and fate
Particulate forms
May be very abundant in sediments.
Impact on water quality depends on local conditions.
Dissolved forms are more biologically “available”.
Phosphorus may be extremely soluble under certain chemical conditions (high pH, low oxygen) but comes out of solution in presence of iron, aluminum, magnesium, calcium in soil
Phosphate ion (PO43-) is the form utilized by plants
(AKA: Orthophosphate, Soluble Reactive Phosphorus)
Highly reactive, usually very low free concentrations
Reacts with iron oxides, calcium, mg, aluminum
Vertical distribution of oxidized and reduced conditions in lake sediments
(Mortimer, 1942)
Dep
th (
cm)
“Old” paradigm: (Mortimer 1942)Redox condition of sediments controls P release
pH affects phosphate adsorption with Fe(OH)3
We now understand that soluble versus particulate phosphorus may be controlled be chemical make-up of sediments and inflow water. Dominance of one form over another depends on rates, mixing, residence times.
Oxygen concentration of sediments and overlying water–
• Controlled by iron, aluminum compounds Microbial decomposition of organic bound P Dissolution of calcium-bound or manganese bound P pH of water Temperature
Epilimnetic phosphorus settles into hypolimnion where it is transformed further and may increase due to sediment release.
When lakes turn over, phosphorus is mixed back into entire water column
Variability in phosphorus in natural waters:
Higher concentrations of TP during high flows (associated with high sediment)
Biologically available forms may be extremely lowduring growing season
Daily and seasonal fluctuations in DO, pH may result in fluctuations of some forms of phosphorus
Extent of internal loading in reservoirs and lakes.
Nitrogen Cycle
Natural nitrogen sources:
Fixed atmospheric nitrogen
lightning
biologically mediated
Decomposition of organic materials
Human nitrogen sources
Synthetic fertilizers
Nitric and nitrous oxides in atmosphere (from burning fossil fuels)
Animal waste
Septic tanks
Wastewater treatment
Nitrogen is found in different inorganic forms
Ammonia/ Nitrite Nitrate Nitrogen gas Nitrous oxide Ammonium
(NH3) (NO2-) (NO3
-) (N2) (N2O) (NH4
+)
Very soluble
Move rapidly through soils into groundwater
Nitrate / nitrite can be toxic at high concentrations
Ammonia toxicity depends on pH and temperature and how long fish are exposed.
Nitrogen cycle:
Animal (Proteins)
Plants (proteins)
Water:NO3 and NH3
Soils(clay surfaces)
Detritus and Manure:Organic N and NH3
Atmospheric N:N2 , NxO, and NH3
Nitrogen FixationN2 NH3
(aerobic bacteria)
Nitrification NH3 NO2 NO2- NO3
(aerobic bacteria)
Denitrification NO3 N2O or N2
(anaerobic bacteria)
Nitrogen often described according to common chemical tests:
Nitrate + nitrite (NO3 + NO2)
Ammonia (NH3)
Total Kjeldahl Nitrogen (TKN) = organic N + ammonia nitrogen
Total Nitrogen = TKN + Nitrate + Nitrite
Other common “fractions” of nitrogen
Oxidized nitrogen = nitrate + nitrite
Inorganic nitrogen = oxidized nitrogen + ammonia
Organic nitrogen = TKN – ammonia
Total nitrogen = TKN + oxidized nitrogen
Variability in nitrogen concentrations in natural waters
May have higher concentrations of TN during high flows (associated with runoff)
Generally ammonia and nitrite very low in unpolluted waters
Nitrate may decline during growing season
BUT DIN may increase in concentration during base flow
Toxic forms of ammonia (NH3+) may vary due to daily and seasonal fluctuations in pH and temperature
PhosphorusPhosphorus NitrogenNitrogenGeochemical Cycling Slow Fast
Human-caused sources Human /animal waste, fertilizer, sediment
Human/animal waste, fertilizer, burning fossil fuels
Gaseous form? No Yes
Soluble forms OrthophosphateDissolved organic
Nitrate / nitrite / ammonia
Movement through soil / groundwater?
Often no Yes
Atmospheric deposition? Dust NOx, Ammonia
Toxic? NO Some forms
Causes eutrophication? Yes Yes
Limiting nutrient? Sometimes Sometimes
Impacts of Excess Nutrients
Problems caused by oxygen depletionProblems caused by oxygen depletion
Loss of fish and other aquatic lifeLoss of fish and other aquatic life
Enhanced phosphorus release from Enhanced phosphorus release from
sedimentssediments
Problems caused by excess plantsProblems caused by excess plants
Loss of aesthetic valueLoss of aesthetic value
Loss of recreational valueLoss of recreational value
Loss of fish habitatLoss of fish habitat
University of Michigan photo
Harmful algal bloomsHarmful algal blooms
Toxicity Toxicity
Liver toxins Liver toxins
NeurotoxinsNeurotoxins
RashesRashes
Drinking water impacts Drinking water impacts
– – surface water sourcessurface water sources
(1986,1987 average water use, figure from UDNR)
Bob Clement, EPA Region 8
Drinking water treatment issuesDrinking water treatment issues
Nitrates in groundwaterNitrates in groundwater
(1986,1987 average water use, figure from UDNR)
Blue baby syndromeBlue baby syndrome
At concentrations above above 10 ppmAt concentrations above above 10 ppm
Young ruminants and other livestock also susceptibleYoung ruminants and other livestock also susceptible
Ammonia toxicity Ammonia toxicity
Ammonium (ionized) form is not toxic fishAmmonium (ionized) form is not toxic fish
Unionized form is very toxicUnionized form is very toxic
Ratio of the two depends on pH and temperatureRatio of the two depends on pH and temperature
Reef Central http://www.reefcentral.com/forums/index.php?s=
Eutrophication –ecosystem effectsEutrophication –ecosystem effects
Zooplankton may be selective grazers
diatoms, green algaemore edible algae
Cyanobacteria (blue green algae) – less edible – may be in large colonies, gelatinous, toxic
Phosphorus impacts –
Nutrient concentrations, algal abundance (Chl a) and water transparency
Sewage diverted
Limnology and Oceanography, 1981
The Lake Washington Story
http://www.kingcounty.gov/environment/waterandland/lakes/lakes-of-king-county/lake-washington/lake-washington-story.aspx
Industrial scale fixation of atmospheric N to ammonia
Today, this process responsible for deeding ~ 1/3 of earth’s population.
Process consumes ~ 1% of world’s energy use
On average 50% of nitrogen in human body is synthetic
Haber-Bosch process
1 kg N /ha = 100 mg/m2
Estimated total reactive nitrogen deposition from the atmosphere (wet and dry) – early 1990s. Biggest increases in industrialized nations – automobile exhaust, agricultural fertilization, other sources www.cbd.int/doc/gbo2/cbd-gbo2.pdf
Nitrogen impacts -
Drainage from Mississippi River Basin Hypoxia Zone in Gulf of Mexico
Areal extent of Gulf of Mexico bottom water
hypoxia
Mississippi River nitrates at St. Francisvile
... Nitrate-N (mg/liter)
__ Nitrate_N flux (million MT/yr)
Estimated nitrogen fertilizer use in the Mississippi River Basin
Estimated land drainage in Mississippi River Basin
1900 1920 1940 1960 1980 2000
From USDA 1987, Goolsby et al 1999, Rabalais et al 1999
• Humans are adding 125 MT/Year to N Cycle• Total addition to terrestrial regions is 390 MT/Year• Total denitrification is 317 MT /Year
By one estimate, balance could be reached by reducing human additions to 52 MT/Year
Controlling nutrients – Controlling nutrients – Which nutrient?Which nutrient?What sources?What sources?
Directly Measuring Nutrient LimitationDirectly Measuring Nutrient Limitation Whole-lake bioassay: Whole-lake bioassay: Lake 226Lake 226in Canadian Experimental Lakes Areain Canadian Experimental Lakes Area
http://www.umanitoba.ca/institutes/fisheries/226curt.jpg
AddedN + C
N + P + C
Schindler concluded thatP limited algal growth in Lake 226
Lake 226 North
Lake 226 South
P-limitation and N-FixationP-limitation and N-FixationSchindler’s argumentSchindler’s argument
David Schindler argued that N should never be limiting, David Schindler argued that N should never be limiting, because if it were, then N-fixing cyanobacteria would because if it were, then N-fixing cyanobacteria would invade and fix readily available nitrogen gas (Ninvade and fix readily available nitrogen gas (N22) into ) into
ammonia:ammonia:
NN22 + energy (photosynthesis) + energy (photosynthesis) NH NH33
Bottle/or Microcosm Nutrient addition bioassays
for assessing nutrient limitation
Elser, J.J. et al. 2007. Nitrogen and phosphorus limitation of primary producers in freshwater, marine and terrestrial ecosystems. Ecol. Letters 10:1-8.
Re
sp
on
se
Ra
tio
Meta-analysis of Meta-analysis of hundreds of hundreds of
bioassaysbioassays
Regional Differences in N vs P limitationRegional Differences in N vs P limitation
3 general approaches for managing nutrient 3 general approaches for managing nutrient loadingloading
Reduction in nutrient inflowReduction in nutrient inflow
Approaches for Managing Nutrient Loading Approaches for Managing Nutrient Loading
Disruption of internal nutrient cyclesDisruption of internal nutrient cycles
Approaches for Managing Nutrient Loading in Approaches for Managing Nutrient Loading in aquatic systemsaquatic systems
Acceleration of nutrient outflowAcceleration of nutrient outflow
Vollenweider loading model
Sedimentation rate, rs ≈ rf 0.5 (unitless)
Hydraulic flushing rf ≈ outflow volume / Lake volume (unitless)
But see:Brett, MT & MM Benjamin. 2008. A review and reassessment of lake phosphorus retention
and the nutrient loading concept. Freshwat. Biol. 53: 194-211
Tropic State Index (TSI)
Carlson (dipin.kent.edu/tsi.htm)
Continuous index from 0-100 based on either:
Chlorophyll Secchi depth
TP
Defining EutrophicationDefining Eutrophication Arbitrary scalesArbitrary scales
Run thru an example of loading Run thru an example of loading model / vollenweider…model / vollenweider…
In class.In class.
Phosphorus criteria in Utah :
Although TMDLs are site specific, often….
0 .05 mg/liter probably will be stream concentration end point 0.025 mg/liter probably will be lake concentration end point
With no TMDL, these concentrations are “indicators”
Relationship between TP and algae holds in many regions
In Utah, probably over-estimates “bioavailable” phosphorus
Nitrogen criteria in Utah :
Ammonia Criteria established for specific pH
and temperature conditions
NitrateNo criteria set for most uses
Indicator concentration of 4 mg/liter
Nitrate drinking water source criteria = 10 mg/liter
Nitrogen cycle:
Animal (Proteins)
Plants (proteins)
Water:NO3 and NH3
Soils(clay surfaces)
Detritus and Manure:Organic N and NH3
Atmospheric N:N2 , NxO, and NH3
Nitrogen FixationN2 NH3
(bacteria)
Nitrification NH3 NO2 NO2- NO3
(aerobic bacteria)
Denitrification NO3 N2O or N2
(anaerobic bacteria)
Transformations:
Physical processes:
sorption of ammonia to organiz and inorganic forms Volatilization
Microbial processes: Ammonification: transofrmation of organic nitrogen
to ammonia (2st step of mineralization)Can occur both aerobically and anaerobically.
Nitrification of ammonia: principle transformation mechanism – reduces 2 step process: Ammonium + Oxygen and Nitrosomonas (hetertrophic bacteria) NitriteNitrite + oxygen and Nitrobacter nitrate.
$$$ Costs?? $$$$$$ Costs?? $$$
Prevention is always cheaper than Prevention is always cheaper than treatmenttreatment
Value of fisheries and recreationValue of fisheries and recreation
Drinking water treatmentDrinking water treatment
New wells, sources of groundwaterNew wells, sources of groundwater
Health impactsHealth impacts
Eutrophication Causes: Increased nutrient availability
Eutrophication Interactions
Increase P & N Loading
Algal Growth
Hyplimnetic Deoxygenating
Zooplankton Refuge
Loss of cold-water fish habitat–
–
Zooplankton Size
–
% Colonial Cyanobacteria(cyanotoxins)
+
Anoxic Nutrient Release
+
+
Fish
+
Zooplankton Grazing
–
+
–
+
Sedimentation Rate
+
Macrophytes&
Periphyton
–
Transparency
–+
Eutrophication issues in Farmington Bay and the Great Salt Lake
Beneficial Use Designation
Farmington Bay
Aquatic WildlifeBrine shrimpBrine fliesBirds
Contact RecreationSwimmingHunting
Public healthOdors
0
500
1000
1500
2000
2500
mg
P
m-2
yr
-1
Jordan River + Central Valley - wetland removal
South Davis WWTP
Central Davis WWTP
North Davis WWTP
Sewer CanalEutrophic
Hyper-Eutrophic
Nutrient loading of one million+ people from WWTP to the shallow bay is extremely high, with predictions of
hypereutrophic conditions
Map & bidirectional flow
x
x
x
Waste Water Treatment
X Sampling stations
Waste Water TreatmentWaste Water Treatment
X Sampling stations
Gunnison Bay
Gilbert Bay
FarmingtonBay
P L
oad
ing
( m
g P
m-2 y
r-1 )
0
100
200
300
400
500
600C
hlor
ophy
ll a
(u
g / L
) +- S
E
Farmington Bay
Gilbert Bay
A O D F A J A O D F A J A O D F A J A O D
2002 2003 2005
2005 Ave.270 ug/L
Hypereutrophic
Eutrophication
High nutrient loading produces excessive
algal growths
At salinities < 5%, a large portion of the algal
biomass is often composed of toxic
cyanobacteria (blue-green algae),
Nodularia spumigena
http://www.cdc.gov/hab/cyanobacteria/default.htm
0
10
20
30
40
50
60
70
80
90
100
UTAH'S 130 PRIORITY LAKES
TROP
HIC
STA
TE I
NDEX
Farmington Bay
Trophic State Index
0
10
20
30
40
50
60
70
80
90
100
UTAH'S 130 PRIORITY LAKES
TROP
HIC
STA
TE I
NDEX
Farmington Bay
Trophic State Index
0
10
20
30
40
50
60
70
80
90
100
UTAH'S 130 PRIORITY LAKES
TROP
HIC
STA
TE I
NDEX
Farmington Bay
Trophic State Index
Although it is not on the Utah’s 303d list of impaired waters, Farmington Bay is the most
eutrophic water body in the State of Utah.
http://
Phosphorus (mg / L)
Farmington Bay 2005
www.forester.net/sw_0201_evaluating.html#b
Algal densities in Farmington Bay are extreme.
The chlorophyll concentration in Farmington Bay in 2005 (270 μg/L; red star) was higher than 750 lakes studied world-wide to relate phosphorus levels to chlorophyll.
Farmington Bay IS “off-the-chart”
0
2
4
6
8
10
122003
DO
(m
g/L
)S
alin
ity
(%)
Salinity @ 0.2 m
O2 - 0.9 m
O2 - 0.2 m
25 K winds
Harsh chemical environment
• Anoxia (diel; several days)
• Toxic ammonia concentrations. >> EPA criteria by 50-400%.
Cyanotoxins from the abundant Nodularia in Farmington Bay are hepatotoxins and tumor promoters. Cyanotoxins accumulate in ducks and advisories for eating ducks have been
suggested for countries boarding the Baltic Sea (Sipia et al. 2006)
Farmington Bay is not safe for swimming!
0
20
40
60
80
100
120
2-May 1-Jun 1-Jul 1-Aug 31-Aug
No
du
lari
n (
ug
-Eq
uiv
LR
)
Farmington Bay
Bear River Bay
Gilbert Bay
Cyanotoxin Concentrations
(2006)
The Capital Times, Madison Sept. 6, 2003
World Health Organization
Moderate Health Effects (20 ug/L)
Mild Health Effects (2-4 ug/L)
Human Health
Harmful Algal Blooms (HABS)
Health effects of contact during recreation (no ingestion):
“Effects of skin irritation, skin rash, as well as vomiting, diarrhea, cold/flu symptoms, mouth ulcers and fever” at above 5,000
cyanobacterial cells per ml” (World Health Organization 2003). Cyanobacterial cells
in Farmington Bay have exceeded this level >100-fold.
Farmington Bay and the Bridger Bay Swimming Beaches Are Not Safe
Waters from Farmington Bay impact Bridger Bay swimming beach.
A rash (somewhat less intense than photo) was viewed on a child playing in water near Bridger Bay that had overflow waters from Farmington Bay (May 2005). These rashes, although severe, are not life-threatening and affect 10-20% of
population (Pilotto et al. 2004).
Farmington Bay Eutrophication Farmington Bay Eutrophication ‘Spilling” into Gilbert Bay‘Spilling” into Gilbert Bay
MODIS MODIS Satellite Satellite Image Image
(30 May 2006)(30 May 2006)FarmingtonFarmington
BayBay
SLCSLC
Causes: Causes: Increased nutrient availabilityIncreased nutrient availability Non-Point SourcesNon-Point Sources
Atmospheric deposition of nitrogenAtmospheric deposition of nitrogen
Atmospheric deposition has increased markedly in industrialized countries from automobiles exhaust, agricultural fertilization and other sources