Transcript Document 7178804

NUTRIENT CONCENTRATION,
DISTRIBUTION AND TRANSPORT
FROM THE EAST COAST CANALS TO
BISCAYNE BAY AND WATER-QUALITY
TRENDS AT SELECTED SITES IN
SOUTH FLORIDA
South Florida Ecosystem Program
INTRODUCTION

Biscayne Bay Is An Oligotrophic Subtropical Estuary
Which Provides Habitat To A Variety Of Plant And Animal
Life

Nutrient-laden Discharges From East Coast Canals
Threaten Ecological Health Of Bay (Biscayne Bay SWIM
Plan)

Ecosystem Restoration Plans Diversion Of Discharges To
Biscayne Bay To Re-establish Natural Flow To Everglades
National Park
INTRODUCTION
(CONTINUED)
 Anthropogenic Activities Are Major Source Of
Nutrients And May Result From Urban And
Agricultural Runoff
•
Adverse Effects Of Excessive Nutrients
•
•
•
•
•
Eutrophication
Algal Blooms
Phytoplankton Growth
Decreased Light Penetration Harmful To Submerged Aquatic
Vegetation
Hypoxia/anoxia
PROJECT OBJECTIVES

Determine Method For Estimating Loads From Canals To
Bay

Characterize Nutrient Concentration And Distribution In
The East Coast Canals

Evaluate Sampling Methods In Order To Document Most
Representative Manner Of Sample Collection

Determine Long-term Trends at Selected Sites in South
Florida
DESCRIPTION OF PROJECT

Samples Collected Upstream Of Gated Control Structures
At East Coast Canals During Periods Of Flow

Depth-integrated And Point Or Grab Samples Collected

Depth-integrated Samples Collected By Equal-WidthIncrement (EWI) Using Weighted Bottle Since Velocities <
2.0 Ft/sec

Instantaneous Discharge Determined for Each Sampling
Event
DESCRIPTION OF PROJECT
(CONTINUED)
 Samples Analyzed For:
• Total Organic Nitrogen
• Total Ammonia
• Total Nitrite And Nitrate
• Total Phosphorus
• Total Orthophosphate
• Kjeldahl Nitrogen (Calculated)
• Total Nitrogen (Calculated)
LOCATION OF SAMPLING SITES
DESCRIPTION OF PROJECT
(CONTINUED)

Depth-integrated Samples Collected By Equal-WidthIncrement (EWI) Method
• Stream Width Subdivided Into Equal Width Intervals
With Sampling Vertical Associated With Each Interval
• Vertical With Highest Velocity Is Selected And Sampler
Is Raised And Lowered At Constant Rate So Bottle Is
Not Overfilled When Returned To Surface
DESCRIPTION OF PROJECT
(CONTINUED)

Depth-integrated Samples (Continued)
• Same Transit Rate Used In All Verticals But Sample
Volume May Be Different
• Samples Composited In Churn Splitter
• Samples Collected In Amber Polyethylene Bottles And
Chilled To 4 Degrees Centigrade And Sent To Lab
FIGURE SHOWING EWI SAMPLING
DESCRIPTION OF PROJECT
(CONTINUED)

Point Or Grab Samples
• Collected At 0.5 Or 1.0 Meter Below Water Surface in
Middle of Stream
• Niskin Bottle Or Van Dorn Sampler
SNAPPER CREEK AT S-22 LOOKING UPSTREAM
SNAPPER CREEK AT S-22 DOWNSTREAM
SAMPLES COMPOSITED IN CHURN AT BRIDGE
UPSTREAM OF S-22
SAMPLES COLLECTED WITH VAN DORN SAMPLER
AT SNAPPER CREEK S-22
DESCRIPTION OF PROJECT
(CONTINUED)
 Nutrient Concentrations In East Coast Canals:
• Total Organic Nitrogen Ranged From 0.20 To 1.7 Mg/l
And Median Was 0.75 Mg/l
• Ammonia Ranged From 0.01 To 1.5 Mg/l And Median
Was 0.10 Mg/l
• Nitrate Ranged From .001 To 4.38 Mg/l And Median
Was 0.18 Mg/l
DESCRIPTION OF PROJECT
(CONTINUED)
 Nutrient Concentrations (Continued)
• Total Nitrogen Ranged From 0.31 To 4.7 Mg/l And
Median Was 1.47 Mg/l
• Total Phosphorus Ranged From .004 To 0.31 Mg/l And
Median Was 0.02 Mg/l
• Orthophosphate Ranged From <.001 To 0.26 Mg/l And
Median Was .005 Mg/l
DESCRIPTION OF PROJECT
(CONTINUED)

Five Sites (G58, G93, S-26, S-27, And S-123) Had
Ammonia Concentrations That Exceeded The Miami-Dade
DERM Standard Of 0.5 Mg/l

Maximum Total Phosphorus Concentration Of 0.31 Mg/l
At G58 (Arch Creek) Was Above Recommended EPA
Upper Limit Of 0.10 Mg/l To Control Eutrophication
DESCRIPTION OF PROJECT
(CONTINUED)

Nutrient Distribution In East Coast Canals Based On Land
Use Categories
• Agricultural (S-20f, S-20g, S021, S21a)
• Urban (G-58, G-93, S-22, S-25, S-25b, S-26, S-27, S28, S-29, S-123)
• Wetland (S-20)
MEDIAN TOTAL ORGANIC NITROGEN CONCENTRATIONS
WERE HIGHEST IN WETLAND AND URBAN AREAS
MEDIAN CONCENTRATIONS OF TOTAL AMMONIA
WERE HIGHEST IN URBAN AREAS
MEDIAN NITRATE CONCENTRATIONS WERE HIGHEST IN
AGRICULTURAL AREAS
MEDIAN TOTAL PHOSPHORUS CONCENTRATIONS WERE
HIGHEST IN URBAN AREAS
DESCRIPTION OF PROJECT
(CONTINUED)
• Comparison Of Grab With Depth-integrated Samples For Total
Nitrogen And Total Phosphorus
• Wilcoxon Signed Rank Test – Exact Form Of The Test Statistic
• Comparison Between Grab Samples At 0.5 Meter Depth And
EWI Samples
• Comparison Of Grab Samples At 1.0 Meter Depth And EWI
Samples
• Comparison Of Grabs At 0.5 Meter Depth And 1.0 Meter
Depth
DESCRIPTION OF THE PROJECT
(CONTINUED)
• Statistical Interpretation Of Differences Between Grab
Samples And Depth-integrated Samples
• Total Nitrogen
• No Significant Differences Between Grabs And
Depth-integrated Samples (P<.025)
DESCRIPTION OF PROJECT
(CONTINUED)
• Statistical Interpretation Of Differences (Continued)
• Total Phosphorus
• Three Sites (25%) Showed Significant Differences
Between Grabs At 1.0 Meter Depth And Depthintegrated Samples
• One Site (33%) Showed Differences Between Grabs
At 0.5 Meter Depth And Depth-integrated Samples
DESCRIPTION OF PROJECT
(CONTINUED)
• Water-Quality Cross-section Surveys
• Document Water-Quality Homogeneity In The East
Coast Canal System
• At Several Sites Temperature, Dissolved Oxygen, pH,
And Specific Conductance Measured Beneath Surface
And At 2-foot Intervals To Streambed
• Dissolved Oxygen Was Only Parameter Showing
Variation In Cross-section
DESCRIPTION OF PROJECT
(CONTINUED)
•
Water-Quality Cross-section Survey At Snapper Creek At
S-22
• Temperature, Dissolved Oxygen, pH, Specific
Conductance Measured From 1.0 Foot Below Surface
Every 2 Feet To Streambed
• Total Nitrogen And Total Phosphorus Samples
Collected Every 2 Feet To Above Streambed
DESCRIPTION OF PROJECT
(CONTINUED)

Water-Quality Cross-section Survey (Continued)
• Discharge Of 414 Cfs During Measurements
• Suspended Sediment Sample Collected By EWI And
By Grab
DISSOLVED
OXYGEN
DECREASED
WITH
DEPTH
TOTAL
NITROGEN
AND TOTAL
PHOSPHORUS
INCREASED
WITH DEPTH
DESCRIPTION OF PROJECT
(CONTINUED)
• Suspended Sediment Sample Collected By EWI Method
Was 3.0 Mg/l And By Grab Method Was 1.0 Mg/l
• Depth-integrated Samples Collected By EWI Probably
More Accurately Reflect Phosphorus Concentration Than
Those Collected As Grabs
DESCRIPTION OF PROJECT
(CONTINUED)
• Relation Between Grab And Depth-integrated Samples
• Line Of Organic Correlation (LOC) Describes Relation
Between Two Variables. No Reduction in Variance of
Estimated Values
Y  Y  SGN ( R)
SY
(X  X )
SX
Y  GRAB
Y  AVERAGE OF GRABS
R  CORRELATIO N COEFFICIENT, SGN(R)  1 if R  1, SGN(R)  0 if
R  0, SGN(R)  - 1 IF R  1
SY , SX  STANDARD DEVIATION
X  EWI SAMPLE
X  AVERAGE OF EWI SAMPLES
DESCRIPTION OF PROJECT
(CONTINUED)
• Grab Samples Underestimate Phosphorus Concentration
Compared To EWI Samples
• S-21 (0.5) Grab = 0.25EWI + .00625
• S-21 (1.0) Grab = 0.2973EWI + .0057
• S-25b (1.0) Grab = 0.8255EWI - .0018
• S-28 (1.0) Grab = 1.093EWI - .008
DESCRIPTION OF PROJECT
(CONTINUED)
•
Determination Of Constituent Loads
L QxCX F
L  LOAD (TONS/DAY)
Q  DISCHARGE (CFS)
C  CONSTITUEN T CONCENTRAT ION
F  CONVERSION FACTOR TO TONS/DAY
DESCRIPTION OF PROJECT
(CONTINUED)
• Discharge Computed Corresponding to Each Sampling
Event
• Fundamental Equations
SUBMERGED ORIFICE FLOW FOR GATED SPILLWAYS
Q  CgsLh 2 g ( H  h)
SUBMERGED WEIR FLOW FOR GATED SPILLWAYS
Q  CW SLh 2 g ( H  h)
ORIFICE FLOW EQUATION FOR CULVERTS
Q  ACC 2 g ( H  h)
DESCRIPTION OF PROJECT
(CONTINUED)
• Linear Regression Analysis To Develop Predictive Models
• Load Was Dependent Variable
• Discharge Was Explanatory Or Predictor Variable
• Best Model Based On Highest R-squared And Lowest
Predicted Error Sum Of Squares (PRESS)
• R-squared Averaged 0.87 For Nitrogen Models And
0.76 For Phosphorus Models
DESCRIPTION OF PROJECT
(CONTINUED)
• Log-linear Model Called Estimator Used At Miami Canal
S-26
• Used For Load Estimation By NAWQA
• Continuous Discharge Data
• Minimum Of 50 Samples For Period Of At Least 2 Years
• Minimum Variance Unbiased Estimator (MVUE) For Elimination
Of Bias From Log Space To Real Space And Adjusted Maximum
Likelihood Estimator (AMLE) For Censored Data
DESCRIPTION OF PROJECT
(CONTINUED)
ESTIMATOR
LnL   0   1 ln Q   2 ln Q 2   3T   4T 2   5 SIN 2t   6COS 2t
Ln  NATURAL LOGARITHM
L  LOAD
 0  CONSTANT
 1 TO  6  COEFFICIENTS
T  DECIMAL TIME
Q  DISCHARGE
SIN 2t  COS 2t  PERIODIC FUNCTION
DESCRIPTION OF PROJECT
(CONTINUED)
• Water-Quality Trends At Two Long-term Discharge Sites
In South Florida
• Miami Canal At S-26 (1966 To 1994). Represents Flow
Through Agricultural, Conservation and Urban Areas.
• Tamiami Canal 40-mile Bend To Monroe (1967 T0
1993). Represents Overland Sheet flow From Big
Cypress National Preserve.
DESCRIPTION OF PROJECT
(CONTINUED)
•
Constituents Analyzed For:
• Major Inorganics And Physical Characteristics
• Field Parameters: Specific Conductance, pH, Dissolved
•
•
•
•
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Oxygen
Suspended Sediment
Nitrogen And Phosphorus Species
Total Organic Carbon
Trace Metals
Fecal Coliform And Fecal Streptococcus
Phytoplankton
TAMIAMI CANAL OUTLETS
OUTLET ON TAMIAMI CANAL IN BIG CYPRESS
NATIONAL PRESERVE
MIAMI CANAL AT S-26
DESCRIPTION OF PROJECT
(CONTINUED)
• Extraneous Variation in Water-Quality Must Be Removed
in Order to Ascertain Anthropogenic Changes on WaterQuality
• Extraneous Variation in Water-Quality Caused by:
• Seasonality
• Discharge
DESCRIPTION OF PROJECT
(CONTINUED)
• ESTREND – A Program For Determining Monotonic
Trends In Water-Quality
• Non-parametric Seasonal Kendall Trend (SKT) Test To
Remove Extraneous Variation
• SKT Applied To Time Series Of Flow-adjusted Concentrations
(Residuals) From Regression Of Concentration With Discharge
• Time Series Of Non-adjusted Concentrations
DESCRIPTION OF PROJECT
(CONTINUED)
• Form Of Linear Models
• Conservative Constituents (Dissolved Solids, Cations And Anions)
C  a  bf (Q )
C  ESTIMATED CONCENTRAT ION
a  INTERCEPT
b  SLOPE
Q  MEAN DAILY OR INSTANTANE OUS DISCHARGE
f (Q)  LINEAR, ln Q, INVERSE 1 , HYPERBOLIC 1
Q
(1  Q )
DESCRIPTION OF PROJECT
(CONTINUED)
• Form Of Linear Models (Continued)
• Non-conservative Constituents (Nitrogen And Phosphorus Species,
Suspended Sediment, Organic Carbon, Bacteria And
Phytoplankton)
LnC  a  b1 ln Q  b2(ln Q)
2
• Non-linear Method – Fitting Concentration/discharge Or
Log Concentration/log Discharge Relation By LOWESS
SUMMARY
•
Nutrient Concentrations Vary In The East Coast Canals
Based On Land Use Categories
•
No Statistical Differences Between EWI And Grab
Samples For Total Nitrogen But 25% Of Sites Showed
Differences For Total Phosphorus
•
Coefficients Of Determination (R2) For Nitrogen Models
Averaged 0.87 And 0.76 For Phosphorus Models
•
Long-term Trends At Miami Canal At S-26 And Tamiami
Canal Showed Both Improvement And Deterioration In
Water-Quality With Time
WHERE DO WE GO FROM HERE?
•
Continued Water-quality Monitoring At Tamiami Canal
And Miami Canal At S-26
•
Continued Water-quality Monitoring At East Coast Canal
Sites
ACKNOWLEDGEMENTS
• South Florida Water Management District Employees
• George Hwa, Control Room
• Ron Dempsey, Supervisor, Homestead Field Office
• Dawn Browning, Supervisor, Miami Field Office