Protocol Bundle For the Science and Measurements of Water Quality

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I. Overview

Water—the main reason for life on Earth—continuously circulates through one of Earth’s most powerful systems: the water cycle. As water interacts with the atmosphere, soil and the surrounding land cover bordering water bodies, and the surface over which the water flows, the water quality changes. Human activity also affects water quality in major ways. Water quality determines what can live in the water body and how the water may be used.

Water quality in general cannot be measured using remote sensing, so the data that GLOBE scientists, teachers, and students collect are vital and help us to become better informed and engaged stewards for the water in our environment. By taking measurements following the protocols in this bundle the GLOBE community will learn about water in their local environment and can collaborate with others around the world. There is no end to what we can achieve through collaboration and cooperation!


II. GLOBE Protocols to study water quality

Precipitation and Precipitation pH

Soil pH

Water pH


Salinity or Conductivity

Dissolved Oxygen


Water Transparency

Water Temperature

Freshwater Macroinvertebrates


III. Science of Water Quality

The temperature of a water body depends on many factors including whether it is shaded or exposed to direct sunlight, depth of water, inputs of melt water from snow or glaciers, heat from geothermal processes, and human uses of the water such as for cooling power plants. Heat exchange occurs between the atmosphere and the water body’s surface. Solar energy warms the water while latent heat released by evaporation cools water.


The transparency of water determines the depth to which light penetrates the water body. It determines how much photosynthesis can occur in the water and influences the amount and types of plants that can live in the water such as submerged aquatic grasses. Transparency and turbidity are closely related terms and more or less opposite terms: transparency measures the extent that light can penetrate a water body, while turbidity examines the amount of materials suspended in the water. The turbidity of water depends on the input of soil particles from the surrounding land through the process of erosion and particles from the atmosphere through interaction at the water’s surface and precipitation. Additionally, the turbulence of the water causes particles to be suspended in the water; greater turbulence allows larger and more particles to be suspended. Larger particles such as sand settle out of the water column much faster than small particles such as clays, particularly in less turbulent water.


As water flows over and through soils and rocks it dissolves salt compounds in them. Precipitation falls as fresh water, but salinity is picked up as it flows with the ocean having an average salinity of 35 parts per thousand. Evaporation increases salinity as water is removed but the salts stay n solution. Estuaries are the regions of intermediate salinity where fresh water in rivers mixes with ocean water.


Chemicals dissolved in water affect its pH, which then determines what can live there. Fresh water in equilibrium with the atmosphere and the carbon dioxide in the air has a pH of about 5.5, Alkalinity buffers the input of acids into water bodies and leads to more stable pH levels in waters with high alkalinity.


As water mixes with air, oxygen (O2) dissolves in the water and is then available for fish and other aquatic animals. Aquatic plants generate oxygen through photosynthesis. When plants die, bacteria digesting the plants remove oxygen from the water sometimes faster than plants and mixing can replace oxygen. This  can produce dead zones where there is not enough dissolved oxygen for fish and other organisms to live.


Although aquatic plants need nutrients to grow and reproduce an excess of nutrients can cause a bloom in plants, particularly the microscopic plants called phytoplankton. An excess of nitrogen and phosphorus compounds are commonly found in excess in water bodies around the world since human activities such as farming and waste water have lots of these compounds flowing into the water either through runoff from the surrounding soils and land cover, point source pollution from sewer outlets, and inputs from the atmosphere.


Water quality is a product of many processes and interactions in the Earth system. Living organisms such as freshwater macroinvertebrates, can be a way to examine the products of the many, often complex interactions. An examination of freshwater macroinvertebrates can indicate water quality as certain types are only found in clean water while others tend to thrive in water of poor quality.


IV. Water Quality Protocols


o   Precipitation l and Precipitation  pH: Aerosols and gases are removed from the atmosphere by precipitation. These aerosols and gases affect the pH of the precipitation. This then affects the pH of soil and surface water. Materials: Installed rain gauge, snowboard, clean containers for pH samples 100-mL or larger, two or three containers for snow samples, Carpenter’s level, meter stick, pH paper OR meter and pH buffers, salt and salt card or tweezers, sampling jar with lid, 300-mL beakers or cups, stirring rods or spoon, latex gloves

Pedosphere (Soil)

o   Soil pH: As water flows through soil it dissolves chemicals that can change the pH or alkalinity of the water body., Materials: [Measuring using pH Paper:pH Paper,100-mLbeaker,Lake glove][Measuring with pH meter:pH meter,distilled water, clean paper towel or soft tissue,pH 7.0,4.0,10.0 buffer solution, Three 100-mL jars with lids, 100-mL Beaker)


o   pH Protocol: pH affects most chemical and biological processes in water, and. has a strong influence on what can live there; aquatic organisms have certain pH ranges they prefer or require. Materials: pH paper, 50-mL or 100-mL beaker, latex glove, pH meter and calibration solutions

o   Alkalinity Protocol: Alkalinity is the measure of the pH buffering capacity of the water. This is strongly influenced by the surrounding geology. Places with limestone tend to have higher alkalinity values. Materials: Alkalinity test kit, distilled water, latex gloves, safety goggles

o   Dissolved Oxygen Protocol: There is much more oxygen available in the atmosphere for animal respiration than in water. Roughly, two out of ten air molecules are molecular oxygen. In water, however, there are only five or six oxygen molecules for every million water molecules. The amount of dissolved oxygen in the water determines what can live there. Materials: Dissolved oxygen kit or probe, 100-mL graduated cylinder, 250-mL polyethylene bottle with lid, watch, thermometer, Solubility of Oxygen Table, Correction for Elevation Table

o   Water Transparency Protocol: How clear is the water? This influences what can live in the water an how people can use the water such as for drinking or irrigation. . Materials: Secchi disk, meter stick, transparency tube cup, latex gloves, Cloud chart

o   Water Temperature Protocol: Water temperature influences the amount and diversity of aquatic life, and the rate of chemical reactions going on in the water. Materials: Thermometer, watch, string, rubber band, latex gloves.

o   Nitrates Protocol: Nitrogen is an essential nutrient for the growth and reproduction of plants. Materials: Nitrate test kit, watch, latex gloves, goggles, surgical mask, distilled water

o   Freshwater Macroinvertebrates Protocol: Macroinvertebrates can tell us a lot about the conditions within a water body. Many macroinvertebrates are sensitive to changes in pH, dissolved oxygen, temperature, salinity, turbidity and other changes in their habitat. Materials: Equipment used to collect water chemistry measurements at your Hydrosphere Study Site (optional), latex gloves, many clear plastic jars (0.5 to 3 L), many small plastic vials, one to four plastic squirt or spray bottles (1 to 2 L), many 20-mL bulb basting syringes (end should be approximately 5 mm diameter), several eyedroppers (end should be approximately 2 mm diameter),large and small plastic or metal forceps, several magnifying glasses or loupes, two to six 5-L white buckets, white trays, two sieves: one 0.5 mm (or smaller), and one between 2-5 mm locally-applicable macroinvertebrate identification key, kick-net, stopwatch, square or white fabric (110cm x 110cm), D-net, trowel or shovel


Guiding Questions:

-       What is the quality of the water in my environment?

o   Is my water safe to drink?

o   Is my water safe to swim or bathe in?

o   Is my water safe to water crops and plants?

-       What impacts does water- both above and below ground- have on our environment?

o   If we have a large rain event, will it flood?

o   Can we grow crops in our soil now?

o   Is my area prone to erosion and landslides?

-       How does water quality impact living organisms?

o    What types of macroinvertebrates in the water body? How has water quality been affected by human activities?


Data reported from measurements included in this bundle can have many uses locally, for downstream communities, and throughout your watershed.




Compiled by: Claudia Caro and Olawale Oluwafemi (Femi)

Edited by: Dr. Dixon and Prof. Cartalis