1. Measuring Total Suspended Solids (TSS)
Vacuum Filtration & Imhoff Cones
Image Source: oos.soest.hawaii.edu

2. Turbidity Turbidity: measure of relative sample clarity
Increases with TSS (or SPM)
Soil particles, algae, plankton, microbes, other debris
Size range of mm (clay) to 1.0 mm (sand)
Affects how much light is scattered
Increased turbidity = Increased scattering of light
Can affect water color
 Turbidity = the cloudiness or haziness of a fluid caused by large numbers of individual particles that are generally invisible to the naked eye, similar to smoke in air. The measurement of turbidity is a key test of water quality.

3. Turbidity Can be natural: Rainfall and Runoff Hurricanes and Flooding
Water currents
River deltas
Natural soil erosion & deposition
Decaying plants & animals
Animal activity (e.g., bottom feeding fish)
Algal blooms
Top left: Mississippi River Delta, Gulf of Mexico
Top right: ???
Bottom left: Lake Eerie (2011)
Bottom right: Gulf of Mexico (Hurricane Katrina)
Image Sources: noaa.gov; wired.com; tcmud.org; commons.wikimedia.org

4. Turbidity Can be anthropogenic: Dredging Boat activities Outfalls
Expedited soil erosion
Dredging image: Freemantle Port in Australia
Boat image: CFCC boat on Cape Fear
Outfall image: Puget Sound, Washington state
“Expedited Soil erosion”  Caused by human disturbance of land surfaces, such as:
Building and road construction
Forest fires
Logging
Mining
Image Sources: pugetsoundkeeper.org; cfcc.edu/martech; dredgeresearchcollaborative.org

5. Measuring Turbidity: Secchi Disk
In Slow-moving and/or Deep Waters:
Secchi disk: Measures light attenuation
Secchi disk = tells us how far light can penetrate (in meters)
Primarily used as an indicator of algal abundance and general water productivity
Rule of Thumb: light penetrates 2-3x Secchi depth
A Secchi disk is an 8-inch (20 cm) disk with alternating black and white quadrants. It is lowered into the water of a lake until it can be no longer seen by the observer. This depth of disappearance, called the Secchi depth, is a measure of the transparency of the water.
Attenuation: gradual loss in intensity
Image Sources: geoscientific.com; ecy.wa.gov

6. Measuring Turbidity: Nephelometer
In Fast-moving and/or shallow Waters:
Nephelometer (Turbidimeter): Measures scattered light
Nephelometric Turbidity Units (NTUs)
Has a photocells set at 45° and 90° to the direction of the light beam to estimate scattered light (rather than absorbed light)
This measurement generally provides a very good correlation with the concentration of particles in the water that affect clarity
Nephelometer  from “nephele” (Greek) meaning “cloud”
Nephelometry is the measurement of the Tyndall effect:
Tyndall effect = light scattering caused by the suspended particles (in any media, including water and air)
A turbidity meter consists of a light source that illuminates a water sample and a photoelectric cell that measures the intensity of light scattered at a 90 angle by the particles in the sample. It measures turbidity in nephelometric turbidity units or NTUs. Meters can measure turbidity over a wide range from 0 to 1000 NTUs. A clear mountain stream might have a turbidity of around 1 NTU, whereas a large river like the Mississippi might have a dry-weather turbidity of around 10 NTUs. These values can jump into hundreds of NTU during runoff events. Therefore, the turbidity meter to be used should be reliable over the range in which you will be working. Meters of this quality cost about $800. Many meters in this price range are designed for field or lab use.
Although turbidity meters can be used in the field, volunteers might want to collect samples and take them to a central point for turbidity measurements. This is because of the expense of the meter (most programs can afford only one and would have to pass it along from site to site, complicating logistics and increasing the risk of damage to the meter) and because the meter includes glass cells that must remain optically clear and free of scratches.
Image Sources: etslabs.com; hach.com

7. Turbidity: NC Waters Average NTUs: Marine: Approximately 25 NTUs
Fresh: Approximately 50 NTUs
Trout Waters: Approximately 10 NTUs
Trout waters are defined in the Environmental Management Commission Rule (15A NCAC 2B .0202) as “waters which have conditions which shall sustain and allow for trout propagation and survival of stocked trout on a year-round basis”. All named and unnamed tributaries to trout waters usually carry the trout waters classification. This classification does not and is not intended to provide public access to streams for fishing on private and public lands and does not regulate, in any way, fishing activities (seasons, size limits, creel limits, and bait and lure restrictions) handled by the NC Wildlife Resources Commission. (

8. Turbidity
&
Fish
Adapted from “Turbidity: A Water Quality Measure”, Water Action Volunteers, Monitoring Factsheet Series, UW-Extension, Environmental Resources Center
Generic, un-calibrated impact assessment model based on Newcombe, C.P., and J.O.T. Jenson Channel suspended sediment and fisheries: A synthesis for quantitative assessment of risk and impact. North American Journal of Fisheries Management. 16:
Image Sources: waterontheweb.org

9. Measuring TSS in the Lab
Millipore Vacuum Filtration & Imhoff Cones
Image Sources: medicalexpo.com; maxlabor.com.br

10. Millipore Vacuum Filtration
Measures all suspended particulate larger than 0.45 μm
Before Filtration
After Filtration
Filters that we are using = 0.45 micron
Image Source: emdmillipore.com

11. http://www. ecy. wa. gov/programs/wq/plants/management/joysmanual/4tss
Image Sources: ecy.wa.gov

12. Imhoff Cones Measures settleable solids Often used by:
in one liter of sample water
Often used by:
Waste water treatment facilities
Aquaculture facilities
Agriculture (irrigation runoff)
Image Source: bioaqua.vn

13. Example Data Table: One Water Sample
    Filter    #
    Tare    
    Gross    
    Net    
Corrected   Net    
Liters     Filtered    
TSS     [mg/L]    1 2 3
Blank 1 4
Blank 2 5
Blank 3 6
Avg. blank change
Blank Correction
Example Data Table: One Water Sample
(mg)
(mg)
CFR 1
66.5 mg
85.6 mg L
CFR 2
66.8 mg
86.9 mg L
CFR 3
66.7 mg
86.0 mg L
66.3 mg
65.9 mg
66.0 mg
66.2 mg
Have the students help fill in this table

14. Calculation SPM in mg/L = W2 – W1 ± X V Variables:
W2 = GROSS WEIGHT (in mg)
W1 = TARE WEIGHT (in mg)
X = BLANK CORRECTION (in mg)
(+ or - as appropriate)
V = VOLUME (in Liters)
Note: W2 – W1 ± X is the CORRECTED NET!