NRES 251 - Water Exam II

What causes acid rain?

NO_x and SO_x.

Alkalinity

the ability of a water body to resist acidification. It comes from limestone in parent material.

Most waterbodies have a pH of…?

6-8.

What did the Romans use for pesticides?

Burning brimstone (sulfur) and heavy metals.

What was used circa 1900 to kill insects in apple orchards?

Lead arsenate.

What pesticide made the shells of bald eagle eggs dangerously thin and fragile?

DDT.

What intense chemical calls deformation and reproductive issues in amphibians after leaching into waterways?

Atrazine.

What affect did Roundup have on the surrounding organisms?

Research is now indicating that glyphosate impacts hormones in amphibians and embryo development in vertebrates. Weeds are also showing resistance to glyphosate.

What will using the same pesticides every year do to the local pests?

They will develop immunities.

Hydrocarbons

any compound that contains only C and H atoms.

Why is crude oil such an issue?

It is a combination of various hydrocarbons (75% aliphatic - nontoxic; 15% aromatic - toxic; 10% other).

What’s the deal with aromatic carbons?

These structures are in a ring form, each point representing a carbon. Because of this structure and that every carbon is double bound to itself, they are persistent. They don’t break down as readily and are very toxic to organisms.

Compare small amounts of oil to large oil spills.

Small amounts of oil are just as bad as the big oil spills, which also indicates our need to revise the stormwater drains we have. 

PCBs

Polychlorinated Biphenyls. They are used in electrical/industrial equipment, paints, plastics, and dyes in carbonless paper. They are very stable and persistent, and that’s why they were used. There are 209 different congeners (depending on where the Cl is located on benzene rings). 

PCBs have a half life of…?

23 years.

FCU’s

used as potential indicators of pathogens. If there are lots of them, there will likely be more pathogens.

Synergy

if you look at two separate contaminants at a low concentration, contaminant A and B should have little impact on pathogens. But, if you mix A and B together, they will make a lethal cocktail that will greatly impact aquatic organisms.

Water Table

the line that divides between the unsaturated zone (the vadose zone) and the saturated zone (groundwater). It can move seasonally or decline due to pumping, but it isn’t as erratic as surface water.

Cone of Depression

due to GW pumping, the water table will be depressed.

Radius of Influence

Where we start to notice a bend in the water table elevation that pulls down as a result of the pumping.

Artesian Wells

naturally have enough pressure built up that the water spills out of the wellhead without any pumping. Doesn’t always happen, it’s more of a hit or miss thing.

Capillary Fringe

thin band right above the water table where the soil is partially saturated with groundwater due to adhesion and cohesion. It is a function of soil structure; clay has the thickest capillary fringe due to smaller pores, and sand has the thinnest capillary fringe due to big pores.

Aquiclude

impermeable layer in the subsurface. Can be low permeability clay or rock outcropping/bedrock.

Confined Aquifer

GW with an aquiclude above it. Usually under pressure due to water building up against the aquiclude. 

Potentiometric Surface

level the water rises to in a well. 

Hydraulic Head

elevation of the water table relative to a datum (usually sea level).

How do you measure hydraulic gradient?

Change in water table elevation / distance between two points.

Seepage Velocity

V_s = (dh/dl x K) / n

Variable “Q” means…

Groundwater discharge.

“dh/dl” means…

hydraulic gradient (change in the elevation in the water table divided by the distance between the two points).

Variable “K” means…

hydraulic conductivity (measured in ft per day).

Variable “N” means…

The effective porosity. ALWAYS turn it into a decimal.

What is needed for an actively flowing Artesian well to occur on the landscape?

For the well to be in a confined aquifer and for the potentiometric surface to be above the well casing.

Darcy’s Law: Variable “s” means…

Hydraulic gradient.

Variable “A” means…

cross sectional area in ft². The hardest term to measure well.

What will result in a larger Hydraulic conductivity?

Materials with large pore spaces.

What is true about the groundwater that is located deeper in the aquifer?

It fell on the ground further way from the location you are located at.

Denitrification

using staggered aerobic and anaerobic cells to stimulate phosphorus uptake by bacteria and nitrogen removal by bacteria. They then trick the bacteria into gorging itself on the phosphorus due to stimulation.

Haber-Boesch Process

One of the most important inventions of the 20th century. (Haber received a Nobel prize in 1919 while Bosch got one in 1931). Under extreme temps. And pressure, H_2(g) and N_2(g) can be converted to NH_3(aq). Responsible for population explosion in 20th century due to fertilizer production and the green revolution.

This allows humans to industrially fix nitrogen out of the atmosphere

What is the most common source of chloride contamination in surface waters of the northern latitude regions of the United States?

Road salts.

What can cause a waterbody to have a dissolved oxygen percent saturation that is less than 100%?

Excessive respiration or decomposition.

Which nutrient tends to be the dominant limiting nutrient in saltwater ecosystems?

Nitrogen.

Mineralization or ammonification will release which form of nitrogen?

Ammonium.

Why is denitrification beneficial from a human perspective?

It removes nitrate from waterbodies which is a human health and ecological concern.

Precipitation in the phosphorus cycle is best described as…?

When free dissolved cations such as calcium create a solid species with orthophosphate and settle in the sediments.

What does phosphorus have a high affinity for?

Polyvalent cations such as calcium, iron, and aluminum.

Oligotrophic

low nutrients and “productivity;” usually high clarity.

Epilimnion

The top level. A high-temperature, low-density level of water in a lake.

Metalimnion

The middle level. Rapid temperature changes prevent mixing.

Hypolimnion

The bottom level. Cold water uninfluenced by the air temperature and stays near the maximum density value.

Isothermal

strong winds that can cause a big turnover from top to bottom.

How are riffle, run, pool sequences beneficial to stream ecosystems?

These locations provide diverse and valuable habitat for organisms.

Why are floodplains valuable?

They provide important habitat for fish, waterfowl, and amphibians; they mitigate against extreme flood events; they remove nutrients and trap eroded sediments in flood waters.

What is true of an oligotrophic lake?

It has low primary production, most likely due to low nutrients.

A deep lake that stratifies is prone to low dissolved conditions under which conditions?

When it is eutrophic, during stratification, and only in the hypolimnion.

Why are aerators useful for shallow ponds?

They disrupt ice formation during winter and help add additional dissolved oxygen throughout the year.

What conditions must an area meet to be considered a wetland?

There needs to be saturated soils and /or standing water within 12 inches of the soil surface existing for long enough during the growing season to develop hydric soils and plant communities dominated by hydrophytic vegetation. This needs to occur every five out of ten years. El Nino events, as they are dry, will cause dryer conditions. There must also be hydric soils and hydrophytic vegetation.

Hydric Soils

• soils that were developed under low oxygen conditions.

  • If all of the soil is being taken up by minerals and water, there will not be a lot of room for oxygen.

Hydrophytic Vegetation

plants that have adapted to growing in low oxygen conditions.

Why are wetlands good at carbon sequestration?

There is high primary production in wetland systems. Wetlands are great at taking plant matter and integrating it into soils because in anaerobic conditions slows down decomposition so much that it just accumulates in the soil. Standing water prevents oxygen from reaching organic-rich soils.

Why are wetlands good for denitrification?

Low oxygen conditions favor denitrification. They also help slow down water and capture eroded soil particles. Plant uptake can aid in nutrient removal, as well.

What is happening with the Ogallala Aquifer?

We’ve seen a lot of depletion from unsustainable use of the Ogallala. It’s not easy to do it to the point that these industrial companies have done. Alaska is getting slight gains in their portion of the Ogallala, but the arid regions are the problem right now.

Drawdown

The drawdown is the difference between the pumping water level and the static water level.

Piezometer

used to measure water quality and groundwater level.

How does groundwater move?

Groundwater follows flow paths because it flows through some sort of matrix. Contamination won’t mix throughout the entire aquifer because of this. The shallow groundwater will infiltrate the soil as precip falls, and the further away precip falls the farther groundwater gets pushed down the flow path. Agriculture from further away will take a deeper flow path and pose worse contamination concerns.

What three things does the flow of water through a pipe depend on?

1. Hydraulic head of water at each end and the length of the pipe (hydraulic gradient)

2. The medium (sand vs. clay) that filled the pipe (hydraulic conductivity)

3. The diameter of the pipe (cross sectional area)

Darcy’s Velocity (specific discharge)

Q/A = dh/dl x K

Hydrogen charges: explained

Hydrogen has one proton and electron, while Oxygen has eight protons and electrons. Most folks think the way to make water is to do this: H-O-H. That’s not the case. What ends up happening is they share electrons to bond together. Normally, a tetrahedron would have 109.5 degree angles but because unpaired electrons occupy two locations, the charges are pushed downward and the angle between the two H atoms becomes 104.5 degrees. The reason why this is important is because the bent shape pushes hydrogens to the other side of the water molecule, which gives rise to a negative charge near the unoccupied charges and a positive charge to the occupied charges.

Hydrogen Bonding

Structure of H2O creates a slightly positive charge and one slightly negative charge (dipolar). H2O is attracted to other H2O (cohesion) and other surfaces (adhesion). Hydrogen bonds allow H2O as a liquid to constantly form, break, and reform bonds (high density).

What are the physical parameters of water quality?

• Temperature

• Turbidity/Clarity

What are the chemical parameters of water quality?

• Nutrients

• Road Salts

• Specific Conductivity

• Heavy Metals

• Organic Pollutants (pesticides, hydrocarbons, PCB’s, Emerging Contaminants)

• Acidity

What are the biological parameters of water quality?

• Dissolved Oxygen

• BOD

• COD

• Chlorophyll

Biological Oxygen Demand (BOD)

measures oxygen consumption by decomposition of organic matter over a 5 or 7 day (we would then call it a BOD 5 or BOD 7) period at twenty-five degrees Celsius. ~60% of organic matter is broken down. The most natural method, and typically requires only a bottle of water.

Chemical Oxygen Demand (COD)

measures the amount of oxygen that is consumed by a strong chemical oxidant (titration). Instead of letting bacteria break down the organic matter, we add a chemical compound that is incredibly effective. ~95% of the organic matter is broken down. You can get results near instantly.

Rapid Bioassessment

Chemical analysis. Instantaneous conditions (snapshot at one location in time). Biotic community will reveal if the community was exposed and unexpected pollutants or interactions are occurring.

Eutrophication

increase in organic matter (typically N or P) that results in DO depletion.

Nitrogen Fixation

specific bacteria (rhizobia) attached to roots of leguminous plants are able to “fix” nitrogen out of the atmosphere. Requires a lot of energy → symbiotic relationship with the host plant. In aquatic systems cyanobacteria are capable of fixing nitrogen as well.

Nitrification

 a two-step process done by two different bacteria in aerobic conditions only. Together, they are called a consortia. Nitrosomonas oxidizes ammonium to nitrite and Nitrobacter oxidizes nitrite to nitrate.

Harmful Algal Blooms

Cyanobacteria (blue-green algae) produce a toxin that is harmful to humans and animals.

Red Tide

Algal blooms in marine ecosystems composed of dinoflagellate (Karenia brevis). The toxins stain the water red. They can be strong enough to kill marine organisms and cause respiratory issues with humans through aerosolization of the water. Regular algal blooms only last a couple days, but red tide blooms can last for months. 

Nitrate – NO₃

Highly mobile → leaches into groundwater, common form of inorganic fertilizer, human health concern.

Nitrite – NO₂

Unstable form of nitrogen → never in high abundance and usually indicates reactions are taking place.

Ammonium – NH₄⁺ or Ammonia – NH₃

Ionized form more commonly, abundant in manure, tends to sorb to soil colloids, potential form of inorganic fertilizer, more common form with manure applications.

Ammonium vs Ammonia

As soil increases to about 9 to 9.25, Ammonium will be less dominant and Ammonia is more dominant. As it turns out, Ammonia is very toxic to aquatic life. It basically fries the brains of fish. Luckily, it takes really high pH’s for this to occur. 

Rhizobia

saps sugar from plants. The plants are usually okay with that because when the rhizobia die, it’ll get plant-available nitrogen in response. It’s kind of like a symbiotic relationship.

Mesotrophic

 moderate nutrients, “productivity” and clarity.

Eutrophic

high nutrients and “productivity;” low clarity. High primary production, likely from high phosphorus, and in turn very low clarity. 

Hyper Eutrophic

pea green, not much life in it, and waaay too much algal growth.

Dimictic

There are two turnover events per year.

Dinitrogen gas – N_2(g)

78% of atmosphere, triple bonded → almost completely unavailable to biological organisms.

Organic nitrogen

Nitrogen trapped in organic matter, if mineralized it can slowly release inorganic forms.

Gaseous Nitrogen

NO_x → nitrogen dioxide - NO_2(g) and nitric oxide - NO_(g)

• Lead to acid rain, come from combustion of fossil fuels

Nitrous oxide – N₂O_(g)

• Potent greenhouse gas, potentially produce during nitrogen cycle

Mineralization/Ammonification

bacteria and fungi in the process of decomposition (aerobic and anaerobic) release nitrogen in the form of ammonium. Key process in creating plant available nutrients.

bacteria and fungi in the process of decomposition (aerobic and anaerobic) release phosphorus in the form of orthophosphate. Key process in creating plant available nutrients.

Nitrification

process done by a set of bacteria in aerobic conditions only. Nitrosomonas oxidizes ammonium to nitrite and Nitrobacter oxidizes nitrite to nitrate.

Sorption

Due to positive charge and negative charge on colloids (clay and organic matter) ammonium can sorb. If other cations become abundant then ammonium will de-sorb back into soil solution.

Due to Al/Fe present in clay structures, phosphorus is sorbed onto clay.

Plant Uptake/Assimilation

plants need nitrogen to create essential amino acids for growth. Can either be ammonium or nitrate. Plants also need phosphorus to create compounds such as ATP.

Immobilization

microbes need nitrogen to create essential amino acids for growth. Can either be ammonium or nitrate. Microbes also need phosphorus to create compounds such as ATP.

Erosion

Ammonium sorbed to soil will be eroded into adjacent waterbodies.

phosphorus sorbed to clay will be eroded into adjacent waterbodies.

Leaching

nitrate is very easily leached and moves with water. In accumulates in groundwater and is readily leached into adjacent stream, rivers, wetlands, and lakes.

Inorganic Phosphorous

PO₄^3- (orthophosphate) – inorganic form that is

readily assimilated by biota. Has a strong affinity for polyvalent cations: Ca2+, Mg2+, Al3+, and Fe3+