WQ Parameters Flashcards
What is Water Quality?
Water quality refers to the chemical, physical, biological/ecological characteristics of water.
WQ is a measure of the condition of water relative to the requirements of one or more biotic species and/or to any human need or purpose. It is most frequently referenced to a set of (WQ) standards against which compliance can be assessed. The most common standards used to assess water quality relate to - health of ecosystems, safety of human contact/consumption (also secondary poisoning) and safe drinking water
What are important WQ Parameters?
Temperature
- affects water density, gas solubility chemical reaction rates, organism growth rate, evaporative water losses
- varies seasonally, diurnally, warming climate, thermal stratification, size and temp of inflows
Dissolved Oxygen
- Increase in organic waste -> increase biological growth -> increase in algae (plant vegetation) -> decrease in DO available to organisms -> damage ecosystems
- Saturation concentration of DO: highest at low temperature but demand for basic metabolism is highest at high temperatures
- Warming climate -> warming ocean -> increased biological metabolism -> less O2 + increased nutrients -> loss of biological species
pH
- controls the solubility of nutrients and trace metals, determines availability of these chemicals for use by aquatic life
- determined largely by geology and soils BUT also affected by acid rain and ocean acidification by atmospheric CO2
- change in pH can alter protein functions in organisms
- pH can affect the toxicity of many substances in water
BOD5: amount of oxygen consumed by bacteria and other microorganisms to decompose organic matter
Alkalinity: ability of water to neutralize incoming acid/bases
- low alkalinity = low buffering capacity
- alkalinity is mostly due to presence of carbonates
Hardness: presence of Ca and Mg usually
Turbidity: In open waters: phytoplankton, Closer to shore: re-suspended bottom sediments (e.g. wind in shallow lakes)
- Effects: Modify light penetration, Increase sedimentation rate, Smother benthic habitats, Reduced photosynthesis can lead to lower daytime release of oxygen, Aesthetic character of natural waters
- measured by TSS or Secchi disk
Nitrates: naturally occurring in soil -> forms by microbial decomposition of fertilizers, plants, manures, or other organic residues -> plants uptake nitrates
Phosphates: naturally occurs in rocks, minerals and fertilizers -> plants use P for growth ->animals ingest plants -> plants are degraded releasing P -> water soluble
Conductivity/salinity: ability of a substance/solution to conduct an electrical current. Depends on total ion content in water
What are lake characteristics important to water quality?
Watershed Area / Lake Area: how big is the watershed area compared to the surface area of the lake? surface/area ratio
- 1-5 have lower productivity = better quality water
- > 10 anthropogenic activities, precipitation etc have a bigger effect on the lake
Water residence time: How long does it take for the lake to be “flushed”? time = V/Q
- longer retention time: lake is flushed infrequently, lake is slower to respond, pollutants are trapped
Wind direction - fetch: the length of water over which a given wind has blown without obstruction. Physical disturbance of surface water, waves created
- shallow lake = bottom of sediment is resuspended
What is oligotrophic and eutrophic?
Oligotrophic have low conc. of plant nutrients, usually accompanied by an abundance of dissolved oxygen
Eutrophic lakes (high nutrient load) experience enhanced biological production & excess algal blooms typical of poor water quality
What is the effect of ocean acidification?
increasing acidity = decreasing ability of ocean to act as a sink for CO2
CO2 + H2O -> H2C03 -> will form H+ and carbonates making water more acid
How are lakes formed?
Glacial activity, Crustal movement, Meandering Rivers, Human activity
What effects the chemical processes in estuaries?
Estuary: where river meets the sea
- The quantity and kind of materials transported by the fresh and salt water sources;
- Different chemical reactions that occur in fresh vs. salt water;
- The residence time of river water in the estuary
