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Project E-CLAW (Ecology and the Chemistry of the Los Angeles Watershed)
This page covers notes on the long term monitoring of the Los Angeles River.

Research notes on what may be monitored over time on the river.
Current data
National Geographic FieldScope page for the LA river project.
This project, and many of its protocols, are based on the earlier TIGER project.

Geotagging
Getting GPS readings from iPhone with Whereamiat?
Getting GPS readings with Android with AndroSensor

View LARiverSites in a full screen map


Description of entrance points along the river to take water samples and take observations.

Abstract


Introduction


Materials and Methods

Chemical tests

The majority of materials used to gather and test river samples was included in the "LaMotte low cost water monitoring kit" (product code: 3-5886). This kit included all of the necessary tablets and vials used for measuring coliform bacteria, dissolved oxygen, BOD, nitrate level, pH, phosphate levels, temperature, and turbidity.

Disolved Oxygen

Dissolved oxygen is a measure of the amount of oxygen gas dissolved in a water sample. It is a good indicator of aquatic photosynthetic activity, although turbulent river systems tend to have higher dissolved oxygen levels just through vigorous surface mixing.

Procedure

Before measuring dissolved oxygen record the temperature of the water sample. Then submerge the small vial (Lamotte part 0125) into the water sample. While removing vial from water sample keep it full to the top. Drop two dissolved oxygen test tablets into the vial and let the water overflow. Screw the cap tightly on the tube, more water will overflow. Make sure there are no air bubbles in the sample. Mix by inverting the tube until tablets are fully dissolved, this will take five to fifteen minutes. Use the Lamotte color chart to compare the reacted DO sample and determine the concentration of dissolved oxygen in the sample to the nearest part per million (ppm). To determine the dissolved oxygen percent saturation use the absolute DO concentration in ppm, the testing side altitude in meters, the water temperature in Celsius and the Five Creeks DO calculator site .


Biological Oxygen Demand

Biological oxygen demand (BOD) is a measure of the amount of dissolved oxygen needed by aerobic bacteria in a body of water in order to break down the dissolved organic matter. It's therefore an indicator of the amount of organic matter, such as algae and bacteria, present in an aquatic system.

Procedure

Procedurally, BOD is measured by completely filling a small vial with the desired water sample. After capping said vial, wrap in either aluminum foil or the provided uv-blocking metallic sleeve. Let vial incubate for five days. At the end of the previously-defined incubation period, remove sleeve/foil, remove the cap, and insert two Dissolved Oxygen tablets into the vial. Replace cap and nutate as necessary to dissolve the tablets. Compare the color of the sample to the Dissolved Oxygen color chart. The BOD is calculated by finding the difference between the uncovered Dissolved Oxygen tube and the covered Dissolved Oxygen tube.

pH

The pH is a direct measure of the acidity of a body of water. Running from a typical scale of 0, most acidic, to 14, most basic, the pH of healthy aquatic ecosystems tends to run near a neutral value of 7.

Procedure

Testing a water's pH is testing how acidic or basic the water is. Though a simple and overlooked test, pH is essential to aquatic life. Fish and aquatic invertebrates are adapted to certain pH ranges, indicating to researchers the quality of the water being tested. We test the LA river water's pH to understand it's ability to function as an ecosystem. To test pH a water quality test is needed and a test tube with pH tablets. Fill the line to 10mL and drop the tablet in and wait for 3 minutes for the water to change colors.

Total nitrates

Nitrates are a form of nitrogen found in aquatic ecosystems and are an essential for plant nutrient. However, in excess, nitrates can cause eutrophication by accelerating plant growth and limiting the amount of sunlight that reaches the aquatic life. High levels of nitrates can also be toxic to warm-blooded animals.

Procedure

To test nitrate levels a plastic test tube, from the LaMotte kit, is first filled to the 5mL line. Next the tube is put into a metal sleeve to block out UV light, which can give false readings as the compounds used in the nitrate test are photoactive. Finally one nitrate test table is put into the covered tube to react, with the depth of the resulting pink color used to measure overall nitrate levels.

Phosphates

Phosphorous, like nitrogen, forms the building block of many of the nutrients needed to sustain plant and animal life. Similar to nitrates, a rise in dissolved phosphate levels can also trigger the formation of algal blooms, which can subsequently lead to low dissolved oxygen levels, and an associated decrease in aquatic animal populations. Phosphates are naturally found in soil and rocks, as well as in animal waste.

Procedure

To test phosphorous a water quality kit is needed with test tubes and phosphate tablets. Fill the test tube to 10mL and drop a tablet it, then let it sit for 5 minutes. The level of blue color saturation is used to measure the overall phosphate levels.

Physical Tests

Turbidity


Turbidity is a metric used to determine how hazy or cloudy a fluid is. The more turbid a solution is, the less light passes through it. It is calculated as the percentage of light deflected more than 2.5 degrees from the incoming light (http://www.thermallaminatingfilms.com/haze.php).

Turbidity is useful for telling how many dissolved substances are in the water, but also since photosynthesis requires light, it helps to predict how likely it is for organic plant life to exist.

Procedure


Turbidity is measured by first placing the Secchi disk sticker in the bottom of the circular container supplied with the test kit supplied. The Secchi disk, which is a circular image of alternating black and white quadrants, should be placed slightly off center. Fill the bucket approximately to the turbidity fill line located on the outside of the container. Use the included turbidity chart to compare the appearance of the Secchi disk inside the container. The result is measured in units of Jackson Turbidity Units (JTU).

Air temperature

The air temperature is measured as it affects the water temperature.

Procedure

Air temperature is measured using the liquid crystal thermometer strip on the outside of the LaMotte kit bucket to the nearest degree Celsius. This thermometer strip, located on the outside of the bucket, is used to measure air temperature prior to water testing. If more than one temperature value is highlighted then the average of the highlighted values is taken as the temperature.

Water temperature

Water temperature is important factor in determining how much oxygen gas can be dissolved in the river water, as well as potential of the water to dissolve more solids. The solubility of oxygen is generally inversely proportional to the water temperature, while that of solids is generally in direct proportion.

Procedure

To find the water temperature empty all of the materials out of the water monitoring kit and fill it with water. Wait for two to three minutes and look at the temperature measuring strip located on the outside of the bucket. If more than one temperature value is highlighted then the average of the highlighted values is taken as the temperature.


Mapping and geospatial measurement

The other materials used included a smartphone or similar device for timing (stopwatch can also be used), taking a panorama or similar photograph (such as taking multiple photos and stitching them together using a service such as http://www.panomonkey.com/ is software on a phone itself is not available. Panoramas were then stored on http://www.360cities.net/), and gps location (along with error margin) by using androsensor for android or "where am I at?" for iPhones. Orange peals were used to help measure flow rate, and empty Gatorade bottles attached to twine or fishing line for gathering water samples where the river cannot be easily reached (such as standing above it on a bridge).

Distance

The distance from site 1 for each site along the river was done using the GPS coordinates for each site and the Free Map Tools website. These values were imported into the main data sets for later use in interpolating various metrics along the river as a function of distance downstream from site 1.

Interpolation

In order to estimate the statistically most likely values for river quality metrics along the river, in between the fixed data points, we use a Kriging method described here. There are additional notes on installing and managing this Python package.

Image Map Generation Protocol

  1. Go to “LA River” Google Doc
  2. Select tab for particular date to be mapped (at bottom of page)
  3. File --> Download As --> CSV
  4. Go to www.gpsvisualizer.com/
  5. Select "Plot data points"
  6. Under "Upload your GPS data files here", input the following:
    1. "File #" --> "Choose File" --> Select CSV you just created
  7. Under "General Map Parameters", input the following:
    1. “Output format"-->JPEG
    2. "Title"-->Enter date, no spaces (e.g. 25June2014)
    3. "Background map"--> "US: Demi street-level map w/relief background"
  8. Under "Data Point Options", input the following:
    1. "Colorize this Field"--> “custom field”
    2. "Min"/"Max"--> (Depends on specific map you're making. See values below.)
Water temp (C): 20-40
Water Temp for FOLAR Data (C): 10-40
DO (%):0-100
BOD (ppm): 0-8
PH: 4-10
Nitrate (ppm): 0-40
Phosphate (ppm): 0-4
Turbidity (JTU): 0-100
Trash Coverage (%): 0.0-0.5
Flow Rate (m/s): 0-6
    1. "Custom colorization field"--> Copy and paste name of test, because input is spacing and case-sensitive. Must match exactly……e.g. Air temperature (C)
    2. "Colorization legend"--> "Bottom right"
    3. "Show point names"--> "No"
    4. "Show point descriptions"--> "No"
  1. Select “draw the map”
  2. Click and drag map to desktop. (Make sure file name makes sense)
Note: Maps are generated for the following categories:
  • Air temperature
  • Water temperature
  • Dissolved Oxygen Percent Saturation
  • Biological Oxygen Demand
  • pH
  • Nitrate
  • Phosphate
  • Turbidity
  • Trash coverage
  • Flow rate

Biological Tests

Surface-adhering algae collection


To collect the rock colonizing algae a square piece of microscope slide glass is placed part way through a piece of cork with a groove cut into it (as seen on the adjacent figure). Several of these corks are tied up by a piece of string and tied on to a rock by the river. Rock colonizing algae begin to grow on the surface of the glass as the corks float in the river. After a week the corks are retrieved from the river and the glass slides are removed from the corks, using gloves to avoid possible contamination for later genetic testing, to be places in plastic vials filled with preservatives.
ECLAWCork.png

Free-floating algae collection


The free floating algae test consist of six pieces of unsterilized foam attached with a piece of string and set 10cm apart from each other. The string is tied to a rock by the river and left there for a week. The free floating algae will colonize the inside of the foam. After a week, we return to the testing site and retrieve the samples by squishing the foam into a vials filled with preservatives, using gloves to avoid possible contamination for later genetic testing.
ECLAWSponges.png
Photo of a sponge and cork algae collection string in a river.

Visual analysis

1. Install ImageJ.
2. Select an image from here.3. Using ImageJ select individual species from the image and make a sub-image. Record the upper left-hand corner coordinate of the sub-image in reference to the original image.4. Use one of the following guides to identify the microorganism:A. http://www.msnucleus.org/watersheds/mission/plankton.pdfB. http://wgbis.ces.iisc.ernet.in/energy/stc/biomonitoring_of_wetlands/keys_freshwater_algae.pdfC. http://algalweb.net/algweb2.htm5. Upload the sub-image, along with the classification and selection coordinate, to iNaturalist.6. The lists of links to the sub-images are posted here.

Genetic analysis




Once we retrieve the samples, we run two types of tests to both types of algae. The first test is to visually identify the type of algae. The algae samples in the vial are placed in formalin and then on a microscope. The second test is a genetic sequencing test using ethanol to better identify the algae and to see whether certain genes are being turned on or off.
The main purpose of the algae tests is to identify the type of algae living in the river.



Potentiostat

Software

Windows machines

  1. Download the latest version of Java. For best results use the JDK instead of the JRE for your architecture (64 bit is probably what you want, but 32bit is also available). It can be obtained from the manual download page here (Note: the manual download is the best because it does not try and automatically install McAfee anti virus and the ask toolbar, so use the manual download.).
  2. Once Java is installed, download rxtx from this site It is important to download the version for the processor architecture corresponding with your cpu (32bit or 64bit above). Save this file for the next step.
  3. Download the CheapStat package from this site.
  4. Decompress that file somewhere convenient (right click and choose extract).
  5. Copy the files RXTXcomm.jar, rxtxParallel.dll, and rxtxSerial.dll from the rxtx download to the gui folder from the cheapstat package.
    For best results, unplug all unnecessary usb devices from the computer (keyboards and mice should be fine to leave plugged in).
  6. At this point, when you plug in the cheapstat to the computer, the Windows driver detection should install the necessary usb serial drivers. For best results plug the cheapstat to a usb port at the back of the computer if using a desktop (try not to plug it into a usb hub unless absolutely necessary). If this does not work, you can try downloading them manually from this site (once again pay attention if the system is 32bit or 64bit).
  7. With the cheapstat plugged in open the file CheapStat_111810.jar from the gui folder of the cheapstat package.
  8. With the CheapStat software open, click on the drop down menu "Serial Port" and there should be a device labeled "COMx" (where x denotes a number representative of a usb port, usually between 1-5).
  9. Now use the 4 way d-pad to select a scan by going up/down to highlight menu items, and right to select them.
  10. Once the scan completes, the data should appear in the CheapStat software. Saving to a file is unreliable, but copying to the clipboard and pasting it into Excel works.

Mac Os X

  1. Download the CheapStat package from here.
  2. Open CheapStat_111810.jar from the gui folder, which should bring up a prompt to install Java. Install Java.
  3. When the install completes, download RXTXcomm.jar, and librxtxSerial.jnilib from here.
  4. Copy these files to /Library/Java/Extensions/
  5. At this point the CheapStat_111810.jar should be able to open and display the CheapStat software.
  6. Download the ft232rl serial usb driver from here From most modern Macs, the 64bit package should be used. Open the FTDIUSBSerialDriver.dmg file, and there should be two .pkg files contained within. One may tell you that your os version is incorrect, if this happens use the other .pkg file, and only one is required.
  7. For best results, unplug all unnecessary usb devices from the computer. The keyboards and mice should be fine to leave plugged in during the process.
  8. At this point, plug in the CheapStat via usb. For best results plug the CheapStat to a usb port at the back of the computer if using a desktop. Try not to plug it into a usb hub unless absolutely necessary. Open the CheapStat_111810.jar from the gui folder of the CheapStat package. The the bottom of the "Serial Port" dropdown menu there should be a device labled /dev/tty.usbserial or /dev/tcu.usbserial, followed by a series of numbers. If both exist. Choose either one.
  9. Now use the 4 way d-pad to select a scan by going up/down to highlight menu items, and right to select them.
  10. Once the scan completes, the data should appear in the CheapStat software. Saving to a file is unreliable, but copying to the clipboard and pasting it into Excel works.

Results and Discussion

E-CLAW physical data maps (2014)
Date
Air temperature
Water temperature
Dissolved oxygen percent saturation
Biological oxygen demand
pH
Nitrate
Phosphate
Turbidity
Trash coverage
Flow rate
25 June 2014
AirTemp25June2014
WaterTemp25June2014
DO25June2014
BOD25June2014
pH25June2014
Nitrates25June2014
Phosphate25june2014
Turbidity25june2014
Trash25June2014
Flowrate25June2014
27 June 2014
AirTemp27June2014
WaterTemp27June2014
DO27June2014
BOD27June2014
pH27June2014
Nitrates27June2014
Phosphate27June2014
Turbidity27June2014
Trash27June2014
Flowrate27June2014
1 July 2014
AirTemp1July2014
WaterTemp1July2014
DO1July2014
BOD1July2014
pH1July2014
Nitrates1July2014
Phosphate1July2014
Turbidity1July2014
Trash1July2014
Flowrate1July2014
3 July 2014
AirTemp3July2014
WaterTemp3July2014
DO3July2014
BOD3July2014
pH3July2014
Nitrates3July2014
Phosphate3July2014
Turbidity3July2014
Trash3July2014
Flowrate3July2014
8 July 2014
AirTemp8July2014
WaterTemp8July2014
DO8July2014
BOD8July2014
pH8July2014
Nitrates8July2014
Phosphate8July2014
Turbidity8July2014
Trash8July2014
Flowrate8July2014
10 July 2014
AirTemp10July2014
WaterTemp10July2014
DO10July2014
BOD10July2014
pH10July2014
Nitrates10July2014
Phosphate10July2014
Turbidity10July2014
Trash10July2014
Flowrate10July2014
14 July 2014
AirTemp14July2014
WaterTemp14July2014
DO14July2014
BOD14July2014
pH14July2014
Nitrates14July2014
Phosphate14July2014
Turbidity14July2014
Trash14July2014
Flowrate14July2014
17 July2 014
AirTemp17July2014
WaterTemp17July2014
DO17July2014
BOD17July2014
pH17July2014
Nitrates17July2014
Phosphate17July2014
Turbidity17July2014
Trash17July2014
Flowrate17July2014
22 July 2014
AirTemp22July2014
WaterTemp22July2014
DO22July2014
BOD22July2014
pH22July2014
Nitrates22July2014
Phosphate22July2014
Turbidity22July2014
Trash22July2014
Flowrate22July2014
24 July 2014
AirTemp24July2014
WaterTemp24July2014
DO24July2014
BOD24July2014
pH24July2014
Nitrate24July2014
Phosphate24July2014
Turbidity24July2014
Trash24July2014
Flowrate24July2014
29 July 2014
AirTemp29july2014
WaterTemp29July2014
DO29July2014

PH29July2014
Nitrates29July2014
Phosphate29July2014
Turbidity29July2014
Trash29July2014
Flowrate29July2014
31 July 2014
AirTemp31July2014
WaterTemp31July2014
DO31July2014

Ph31July2014
Nitrates31July2014
Phosphate31July2014
Turbidity31July2014
Trash31July2014
Flowrate31July2014
Animations










E-CLAW time series data (2014)
Air temperature
Water temperature
Nitrates
Turbidity
Dissolved oxygen
Phosphates
pH
Biological oxygen demand


E-CLAW algae data
Deployment date
Collection date
Site
Preservative
Algae type
String
Sample
Images
10 July 2014
17 July 2014
5
Formalin
Free floating
1
c
Link
10 July 2014
17 July 2014
5
Formalin
Free floating
1
a
Link
10 July 2014
17 July 2014
2
Formalin
Free floating
2
c
Link
10 July 2014
17 July 2014
2
Formalin
Free floating
2
b
Link
10 July 2014
17 July 2014
2
Formalin
Surface adhering
3
b
Link
10 July 2014
17 July 2014
2
Formalin
Surface adhering
3
a
Link

Data from FOLAR (2003)
Date
Air Temperature
Water Temperature
Dissolved oxygen
pH
Nitrate
Phosphate (High)
Phosphate (Low)
Turbidity
Flow rate
17
May
2003
AirTemp17May2003
WaterTemp17May2003
DO17May2003
PH17May2003
Nitrates17May2003
PhosHigh17May2003
PhosLow17May2003
Turbidity17May2003
Flow17May2003
28
June
2003
AirTemp28Jun2003
WaterTemp28June2003
DO28June2003
PH28June2003
Nitrates28June2003
PhosHigh28June2003
PhosLow28June2003
Turbidity28Jun2003
Flow28Jun2003
15
July
2003
AirTemp15Jul2003
WaterTemp15July2003
DO15Jul2003
PH15Jul2003
Nitrates15July2003
PhosHigh15July2003
PhosLow15July2003
Turbidity15Jul2003
Flow15July2003
22
July
2003
AirTemp22Jul2003
WaterTemp22July2003
DO22Jul2003
PH22Jul2003

PhosHigh22july2003
PhosLow22july2003
Turbidity22Jul2003
Flow22Jul2003
12
August
2003
AirTemp12Aug2003
WaterTemp12August2003
DOAug122003
PH12Aug2003
Nitrates12August2003
PhosHigh12Aug2003
PhosLow12Aug2003
Turbidity12Aug2003
Flow12Aug2003
9
September
2003
AirTemp9Sep2003
WaterTemp9September2003
DO9Sept2003
PH9Sep2003
Nitrate9September2003
PhosHigh9Sept2003
PhosLow9Sept2003
Turbidity9Sep2003
Flow9Sep2003
14
October
2003
AirTemp14Oct2003
WaterTemp14October2003
DO14Oct2003
PH14Oct2003
Nitrates14October2003
PhosHigh14Oct2003
PhosLow14Oct2003
Turbidity14Oct2003
Flow14Oct2003
11
November
2003
AirTemp11Nov2003
WaterTemp11November2003
DO11November2003
PH11Nov2003
Nitrates11November2003
PhosHigh11Nov2003
PhosLow11Nov2003
Turbidity11Nov2003
Flow11Nov2003
9
December
2003
AirTemp9Dec2003
WaterTemp9December2003
DO9Dcember2003
PH9Dec2003
Nitrates9Decemeber2003
PhosHigh9Dec2003
PhosLow9Dec2003
Turbidity9Dec2003
Flow9Dec2003
Animations
AirTempAnimation2003
WaterTempAnimation2003
DOanimation2003
PHanimation2003
NitratesAnimation2003
PhosHighAnimation2003
PhosLowanimation2003
Turbidityanimation2003
Flowanimation2003

Date
Air Temperature
Water Temperature
Dissolved Oxygen
pH
Nitrate
Phosphate (High)
Phosphate (Low)
Turbidity
Flow Rate
13 Jan 2004
AirTemp13jan2004
WaterTemp13January2004
DO13jan2004
pH13January2004
Nitrates13jan2004
PhosphateHigh13January2004
Phoslow13Jan2004
Turbidity13January2004
FlowRate13Jan2004
10 Feb 2004
AirTemp10Feb2004
WaterTemp10February2004
DO10Feb2004
pH10Febuary2004
nitrates10feb2004
PhosphateHigh10Feb2004
Phoslow10feb2004
Turbidity10Febuary2004
FlowRate10Feb2004
16 March 2004
AirTemp16March2004
WaterTemp16March2004
DO16march2004
pH16March2004
Nitrates16march2004
PhosphateHigh16March2004
Phoslow16March2004
Turbidity16March2004
FlowRate16March2004
13 April 2004
AirTemp13April2004
WaterTemp13April2004
DO13april2004
pH13April2004
Nitrates13April2004
PhosphateHigh13April2004
Phoslow13April2004
Turbidity13April2004
FlowRate13April2004
11 May 2004
AirTemp11May2004
WaterTemp11May2004
DO11may2004
pH11May2004
Nitrates11May2004
PhosphateHigh11May2004
Phoslow11May2004
Turbidity11May2004
FlowRate11May2004
Animations
AirTempAnimation2004
WaterTempAnimation2004
DOanimation2004
pHanimation2004
NitratesAnimation2004
PhosphateHighAnimation2004
Phoslowanimation2004
Turbidityanimation2004
FlowRateAnimation2004

Correlation analysis of FOLAR 2003 data
Motivating citation
Analysis
Independent variable
Error on independent variable
Dependent variable
Error on dependent variable
Best-fit function
Correlation coefficient
citation

Air temperature
0.1C
Dissolved oxygen
0.01mg/L
y = 0.2460983744x + 8.0092352692
0.0113553665
citation

Dissolved oxygen
0.01mg/L
pH
0.1
y = -0.0117925178x + 8.8886681574
0.0136721854
citation

Phosphates
0.01mg/L
Dissolved oxygen
0.01mg/L
y = 0.0030186107x + 1.489138175
0.0005520689
citation

Dissolved oxygen
0.01mg/L
Turbidity
0.1NTU
y = -0.3029922589x + 14.6245378161
0.0175673215


Dissolved solids
1 ppm
Water temperature
0.1 C
y = -0.0022x + 23.095
R² = 0.0038


Total dissolved solids
1 ppm
Dissolved oxygen
0.01 mg/L
y = 0.0107x + 7.7084
R² = 0.0174


Flow Rate
0.01 m/s
Dissolved oxygen
0.01 mg/L
y = -4.7487x + 17.984
R² = 0.0222


Dissolved oxygen
0.01 mg/L
pH
0.1
y = -0.0118x + 8.8887
R² = 0.0137


Dissolved oxygen
0.01 mg/L
Phosphate
1 ppm
y = 0.003x + 1.4891
R² = 0.0006


Dissolved solids
1 ppm
pH
0.1
y = -0.0015x + 9.6005
R² = 0.036


Dissolved solids
1 ppm
Turbidity
0.1 NTU
y = -0.0161x + 18.608
R² = 0.0128


Dissolved oxygen
1 ppm
Turbidity
0.1 NTU
y = 0.0453x + 8.7377
R² = 0.0025


Air temperature
0.1 C
Water temperature
0.1 C
y = -0.1413x + 24.303
R² = 0.4043


Dissolved oxygen
0.01 mg/L
Water temperature
0.1 C
y = -0.0006x + 22.04
R² = 2E-06



Phosphate vs Disolved Oxygen y = -0.7183x + 15.062
R² = 0.0224

Water Temp vs Nitrate y = 0.0068x + 4.2343
R² = 0.0003

Correlation analysis of FOLAR 2004 data
Motivating citation
Analysis
Independent variable
Error on independent variable
Dependent variable
Error on dependent variable
Best-fit function
Correlation coefficient
citation

Phosphates
0.01mg/L
Dissolved oxygen
0.01mg/L
y = -0.7182822063x + 15.061676415
0.0223990938


Water temperature
0.1 C
Nitrate
1 ppm
y = 0.001x + 4.3986
R² = 7E-06


Air temperature
0.1 C
Dissolved oxygen
0.01 mg/L
y = -0.0098x + 14.244
R² = 0.0007


Dissolved oxygen
1 ppm
pH
0.1
y = 0.0332x + 8.5076
R² = 0.1667


Dissolved oxygen
1 ppm
Turbidity
0.1 NTU
y = -0.0547x + 15.526
R² = 0.0004


Dissolved oxygen
1 ppm
Water temperature
0.1 C
y = 0.0711x + 19.254
R² = 0.0064


Nitrate
1 ppm
Phosphate
1 ppm
y = 0.001x + 1.8353
R² = 0.0002

Conclusions

Supporting Information