Quiz 2 Lecture 2 Flashcards
What three things can happen when light interacts with water?
It can absorbed- Converted to heat
Transmitted- Goes to deeper layers of the water
Reflected- goes back to the atmosphere
Why are absorbance and transmittance plots in the opposite direction?
what is not absorbed gets transmitted
In pure water what wavelengths get absorbed? What wavelengths get transmitted?
Longer wavelengths (red-orange) will get absorbed, shorter wavelengths (purple-blue-green) will get transmitted.
What impacts lakes color in terms of light?
The wavelengths of light that are transmitted
Are aborsbance and transmission curves the same in all water bodies?
No, for example if a lot of algae which has pigments that absorb more blue and red, lake can look a lot more greener- more green wavelengths transmitted
Different plant pigments have what kind of different rates of absorption?
they have diff absorption percentages for diff wavelengths
How does photosynthesis rates vary with different wavelengths?
as wavelengths not absorbed by certain plants pigments, photosynthesis rate decreases
How does clarity of water impact photosynthesis?
it will impact how much radiation will be transmitted to different depths and what wavelengths are being transmitted which will impact primary production in the water- for example if a bunch of algae on top for chlorophyll A, radiation may not be transmitted, and red wavelengths of light may not be transmitted as their already absorbed stopping plants at the bottom from absorbing that wavelength and reducing photosynthesis.
The colour of a lake we see is the result of what?
Of what is in the water, particles and dissolves substances will impact how deep the water will penetrate and the wavelengths absorbed/transmitted/scattered
Lake colour depends on the interaction between?
Apparent colour (some wavelengths absorbed, others and transmitted and then scattered) and real colour (the color of the stuff in the water).
What are the physical indicators of water quality? (6)
Total dissolved solids
Conductivity
Total Suspended Solids
Turbidity
Water Colour
What are the chemical indicators of water quality?
pH
* Biological Oxygen Demand
(BOD)
* Dissolved Oxygen (DO)
* Hardness
* Total Nitrogen
* Total Phosphorus
* Heavy metals, pesticides, toxic
substances
What are the biological indicators of water quality?
Bacterial content: E.coli,
Coliform bacteria
* Ephemeroptera
* Plecoptera
* Trichoptera
* Community composition
metrics
* Diversity indices
* Dominance of pollution tolerant
organisms
What indicators do we start with?
Biological indicators bcuz they need low level equipment, then move onto the others
Is the distinction between dissolved and particulate matter arbitrary? What else is it referred to?
Yes, usually defined based on their ability to pass through a filter (can be 0.5-1 um)
other thing it is referred to colloidal and gravitoidal (larger due to settling down due to gravity)
What are Total dissolved solids?
mass of material (inorganic and organic) dissolved
in water, usually measured in ppm.
What’s the ideal range of tds for drinking water? What is the threshold?
0-50 ppm, as u go up more tds (average tap water), near 0 is the closer u are to pure water. Often 2 um.
What is conductivity?
Relative amount of electricity that can be conducted by water
Is pure water very conductive? What makes it more conductive?
No, but as we get more ions then more conductive, is why seawater is more conductive but distilled water not.
What is specific conductance? Why do you have this?
conductivity measure corrected to
25°C to allow for comparison between reported measures of
conductivity, this is because temperature impacts conductivity so it’s just to standarize it
How are conductivity and TDS related? Why do we use conductivity metre field?
conductivity is only impacted by ions that can conduct, TDS is all particles. We use conductivity as proxy of what’s in water bcuz TDS hard to measure.
What is TSS?
dry weight of particles trapped on a filter paper, don’t make it through filter
Can TSS be easily obtained in field?
No
what is Turbidity?
Is measured as the light absorption or scattering of water in order to ascertain how many particles in water, how particles- higher turbidity- more cloudy.
Is turbidity used as a proxy for TSS?
Yes as easier to measure and denotes particles in water.
What is pH?
concentration of hydrogen ions, measures acidity
Why is pH central to aquatic ecosystems?
Central for biological activity
◦ Most aquatic systems are found near neutrality (pH= 7±1)
How does pH impact what organisms we see?
species need diff ph’s, big driver of ecosystem biology
How does pH effect water chemistry?
certain toxic metals are more soluble at low phs
What is alkalinity?
Is buffering capacity, is ability to neutralize changes’ in ph
What is alkalinity measured in?
is mg of equivalent carbonate per litre of water
Why do we care about alkalinity?
Because if you have something alkaline it will be bale to buffer changes in pH
What effects alkalinity?
geology and runoff around water, for ex have geology be limestone and have intense runoff due to snowmelt and ppt
What is hardness? What is it often associated with?
the sum of magnesium and calcium ions present, an indicator of the
ability of water to precipitate soap, important in domestic water supplies.
Often associated with high alkalinity
Soft water has a low ionic content because?
It’s surrounded by rocks that don’t weather easily- ex igneous rock
in hard water have high weathering rocks- shale liemstone
Why is the influence of ppt on softwater high but hard water low?
Hard water can buffer acidic ph
What is biogeochemistry?
chemistry in an environmental context with an emphasis on the living and non-living components of
an ecosystem.
What are the elements essential for macronutrients and micronutrients?
Macronutrients? C, H, O, N, P, K, S, Mg, Ca, (Si) (are essential and relatively high in concentration)
micronutrients? Fe, Cl, Cu, Mn, Zn, Mo, Bo (required in small conc)
What does algae need to grow? How does anthropogenic impacts effect?
need organic and inorganic nutrients, these come from rock weathering, soil leaching, but also human sources - such as agricultural drainage, fertilizer etc
Is silica a macronutrient for all organisms? What organisms are they required for?
No, but diatoms need silica to build their shells
What are nutrients?
any element required by organisms for growth
What are important nutrients?
lipids are phosphorus and carbon rich
* Amino acids and proteins require relatively more nitrogen than most
* Nucleotides and nucleic acids require significant amounts of nitrogen and phosphorus
Can bacteria and primary producers use inorganic nutrients?
inorganic
nutrients, such as nitrate and phosphate can be used
do higher order organisms need organic nutrients?
yes, heterotrophic animals and eukaryotic unicellular organisms acquire their
nutrients in organic form
What’s a biological source of nutrients?
decomposition, ex salmon will reproduce somewhere else and die , they decompose and then bring nutrients into freshwater systems
What is stoichiometry?
how the balance of energy and elements influences living systems
How can you see nutrients availability and requirements?
divide demand by supply, larger numbers mean higher demands
What nutrients are in high demand?
Phosphorus and nitrogen
What is the redfield ratio?
The stoichiometry of carbon, nitrogen and phosphorus at balanced growth is
106:16:1
What is Leibig’s Law of the Minimum?
The element or resource with the least relative amount will limit growth and production, therefore the rate of a process will be limited by the rate of it’s slowest sub process (for ex limited phosphorus means limited lipid production)
Where did the redfield ration originally come from?
ocean, can work in freshwaters generally with some variation- this variation is what causes us to see seasonal cycling in species
How do you experimentally test Leibigs law?
David schindler, did an experiment where he fertilized one side of a lake with carbon and nitrogen and then fertilized the other with carbon, nitrogen, and phosphorus, saw blue-green alage bloom in phosphorus side
What nutrients primarily limit aquatic systems?
Nitrogen and phosphorus (main one)
What is assimilation?
acquisition of nutrients by organisms
What is remineralization?
breakdown of organic matter into biologically available forms
Do we need a balance of assimilation and remineralization?
yes
What are the three processes leading to remineralization?
- Decomposition (plants and organisms will decompose)
- Leakage (leaves falling into water before they decompose, cells break and release content)
- Heterotrophic organisms (organisms that eat plants/ sloppy feeders will release nutrients)
