Chemical and Biological Indicators Water Quality Chemical and Biological Indicators

Why is water quality important? Human health: drinking water Fisheries Water for industry and agriculture Aesthetic reasons Species habitat Water for recreation (swimming, fishing, boating) Ask students to brainstorm why water quality is important to them

What types of tests do we use to measure water quality? Dissolved oxygen Nitrogen (usually nitrate-nitrogen) pH Macroinvertebrates Phosphorus (usually phosphate-phosphorus) Alkalinity Conductivity Chloride Salinity Suspended solids Fecal coliform bacteria There are a large number of different types of water quality tests

Dissolved Oxygen The presence of oxygen gas molecules (O2) in the water. Why is it important? The oxygen in H2O is not dissolved oxygen. Dissolved oxygen is often the most common, and most important, water quality test. It will give you an immediate indication of the health of the aquatic system. What’s coming out of the diffuser?

Dissolved Oxygen How does oxygen get into the water? -diffusion from the surrounding air -during the process of photosynthesis

DO levels are affected by: Altitude Temperature Speed of water movement (dams as well as natural differences and tides) Addition of wastes Vegetation

Hudson River near Newburgh, NY, summer Hudson River near Warrensburg, NY, winter Cold water holds more DO than warm water; fast moving water generally has more oxygen than slower moving waters. However, plant growth (unknown from these images) will also affect DO levels. Which do you think has more DO: the stream on the left or the stream on the right? Why? What else do you need to know?

Different Organisms Require Different Amounts of DO Trout and salmon require high amounts of dissolved oxygen, as do most fish larvae Trout do not do well in waters below 4-5 ppm. Carp and catfish can survive with much less.

How do Humans Affect the Amount of DO in the Water? Addition of oxygen-consuming organic wastes www.al.nrcs.usda.gov

Changing the Flow of the Water Which dam is this? The Croton Dam

Activities That Raise the Water Temperature Allowing vegetation to grow along shorelines will reduce the water temperature. Riparian zone vegetation, power plant cooling Source: http://www.ger.com/indpt.jpg

pH The measure of the acidity of a solution Acids produce H+ (hydrogen ions) Bases produce OH- (hydroxide ions)

Why is pH important? If the pH is too low, it could indicate pollution from acid rain Acid rain can kill insects and other organisms, and harms vegetation, often killing forests (especially in high altitude areas because of acidic fog) Photo courtesy of C. Harris

How is pH measured? -pH is measured on a scale of 0 to 14. -A solution with equal hydrogen and hydroxide ions would have a pH of 7 -What would the pH of a solution be that had more hydrogen than hydroxide ions? -A decrease of one unit on the pH scale is the result of a 10 fold increase in hydrogen ions. Drawing by J. Jenkins

basic neutral The photo is from the Adirondacks, which generally suffers from high levels of acid rain. acidic

How Does pH Affect a River? It changes the availability of different nutrients and metals in the water, making it hard for some animals to survive Metals that leach from the soils when pH changes especially affect immature stages of aquatic insects and fish Fish larvae exposed to biotoxins that cause morphological abnormalities. www.nwfsc.noaa.gov

What Causes a pH Change? Atmospheric deposition (acid rain) Surrounding rocks and soils Wastewater discharges from business and industry Acid mine drainage

Acid Rain in U.S.

Nitrogen Pollution Do you contain nitrogen? Does the air contain nitrogen? What about plants and animals? Everything around us contains nitrogen

Nitrogen …so what? Plants and animals need nitrogen But…there can be too much of a good thing! Too much nitrogen results in…. There is both cultural (human) and natural eutrophication

Nitrogen Pollution Too much nitrogen can cause: Eutrophication Increase in nutrients Aquatic life suffers Increase in plant growth Dissolved oxygen declines as plants are decomposed

Nitrogen in the Hudson Where does it come from? -human waste -acid deposition -fertilizer -agriculture: fixation and feed Where does it go? The nitrogen from the Hudson River ends up in the Atlantic Ocean

Nitrogen: Why so much from the middle of the USA? The middle of the US uses a lot of nitrogen fertilizer to grow crops

1850s Iowa – beige color is prairie 1990s Iowa – beige color is prairie, gray is row crops Source:  Compiled from Landsat Thematic Mapper satellite imagery, Iowa Dept. of Natural Resources.

Humans and the Nitrogen Cycle Last 100 years: humans have more than doubled the amount of fixed nitrogen that is pumped into the atmosphere every year. Consequences: acid rain, ground level ozone, groundwater contamination, surface water pollution, eutrophication The map shows the amount of N deposition show as increased pH (nitrogen oxides from fossil fuel combustion)

Phosphorous Where does it come from? -not a gas -weathers from rock -reuse from already present phosphorous in detritus Why is it important? -less abundant and available than N -often the limiting nutrient in freshwater ecosystems

Phosphorus Cycle Phosphates in rocks are mined Dissolves in water Plants take up inorganic phosphate We create phosphate-rich fertilizer Organisms use organic phosphates Decomposers convert organic waste back to inorganic P in the soil Most of the phosphorous in the world is found in rocks (not as a gas) It is transported by water as the rocks are broken down by weathering Organisms use inorganic P to form bones and other important molecules It gets passed through food chains When the organisms die it is returned to the soil Phosphates are major components of fertilizers. They make plants grow, especially in aquatic ecosystems

Phosphorous in the Hudson Main source: detritus Used by plants during the growing season Some P is lost to the ocean and some becomes buried in sediment

Macroinvertebrates Why do we sample invertebrates?? It’s a way to measure the health of an ecosystem’s aquatic life Scientists usually take several samples, looking at diversity and abundance, as well as species evenness Dobsonfly larvae (helgrammite). Photo from Cary Institute.

Aquatic Ecosystem Biodiversity www.hainaultforest.co.uk www.fresc.usgs.gov www.dkimages.com www.eduwebs.org

Species Diversity Diversity differs depending on: time of year, habitat, ecosystem, sampling location, and water quality Macroinvertebrates are one way to assess water quality, but other measurements should be taken to ensure accuracy Students from Tabernacle Christian Academy, Poughkeepsie

Alkalinity A measure of the capacity of water to neutralize (or buffer) acids Streams with high alkalinity would be able to resist a change in pH more than a stream with low alkalinity Alkalinity is reported as mg/L of CaCO3

What are the Sources of Alkalinity? Compounds that create alkalinity include calcium carbonate, sodium bicarbonate, and calcium hydroxide. Limestone bedrock, like that in the Hudson River, produces water with relatively high alkalinity Photo by H. Malcom

Fecal coliform Fecal coliform bacteria refers to a group of micro-organisms that live in the digestive tracts of warm-blooded animals, such as humans Indicates: sewage or manure http://ucce.ucdavis.edu/files/filelibrary/5453/6581.gif

http://www.waterfilterreview.com/images/contaminants/ h20_contaminants_200/fecal_coliform_200.jpg Health risk for humans due to disease causing bacteria/viruses (hepatitis A and typhoid fever) http://www.water-research.net/images/ICE-TEA2.GIF

Suspended Solids Suspended solids is a measure of how many particles are suspended in the water Caused by soil erosion, sewage discharge, algal growth, and movement of the water It is often measured along with turbidity, which is faster to measure Usually measured in mg/L Photo courtesy of C. Harris

Suspended particles can clog fish gills, smother eggs of fish and aquatic insects, and reduce growth rates. High suspended solids can decrease dissolved oxygen by blocking sunlight for plants and increasing the temperature of the water by absorbing light from the sun. Photo: C. Harris http://www.kbac-hi.org/BMPs/images/tss2.gif