SciOly Water Quality

summer stratification: layer - epilimnion

warm temps, high DO, photosynthesis

summer stratification: layer - metalimnion

rapid changing temps, variable DO, thermocline

summer stratification: layer - hypolimnion

cold temps, low DO, decomposition, can become anoxic

Fall/spring turnover

surface cools and sinks, wind mixes layers, oxygen & nutrients redistributed, can cause temporary algal blooms

winter

inverse stratification, coldest water near ice, low ligh → low photosynthesis

nitrogen cycle processes: fixation

N2→ NH3, anaerobic

nitrogen cycle processes: nitrification

NH4 → NO2 → NO3, aerobic, consumes oxygen

nitrogen cycle processes: assimilation

NO3 uptake, plants/algae

nitrogen cycle processes: ammonification

organic N→ NH4, decomposition

nitrogen cycle processes: denitrification

NO3→ N2, anaerobic sediments

phosphorus cycle

no atmospheric phase, exists PO4, comes from rock weathering, fertilizers, detergents, limiting nutrients in freshwater. Sediments = phosphorus sink, low oxygen → phosphorus released back into water

Carbon Cycle & pH

CO₂ + H₂O ⇌ H₂CO₃ ⇌ H⁺ + HCO, more CO2→lower pH, photosynthesis higher DO, higher pH, respiration lower DO, lower pH

DO

Measured in mg/L, Cold water holds more oxygen, ↓ DO caused by High temperature, High BOD, Nitrification, Decomposition

Biochemical Oxygen Demand

oxygen used to decompose organic matter, high BOD = pollution, common sources: sewage, manure, food waste

pH

logarithmic scale, each until 10× change, ideal freshwater 6.5-8, low pH: metal toxicity increases, egg mortality increases

turbidity

measures water clarity, high turbidity: blocks sunlight, raises temperature, smothers benthic habitat

conductivity

measures ions, high = pollution, sources : road salt, fertilizers, wastewater

hardness and alkalinity

hardness = Ca²⁺, Mg²⁺, Alkalinity = buffering capacity, high alkalinity → stable pH

pollution types: nutrient pollution

nitrates + phosphates, causes eutrophication

pollution types: thermal pollution

power plants, lower DO, thermal shock

pollution types: toxic pollution

heavy metals, pesticides, industrial waste

pollution types: point

pipe, easy to trace

pollution types: nonpoint

runoff, diffuse

eutrophication

nutrient input, algal bloom, light blocked, plants die, bacterial decomposition, oxygen depletion, fish kill (creates hypoxia/anoxia)

bioaccumulation

toxin builds up in the organism

biomagnification

concentration increases up the food chain

top predators

highest level

watershed

area draining into water

urbanization

increased runoff, increased pollution, decreased infiltration

Purple loosestrife

Thrives in moist, disturbed areas.

Outcompetes native vegetation, leading to reduced biodiversity.

Characterized by tall stems and purple flowers (3 to 10 feet high).

Produces numerous seeds that spread easily.

Forms dense stands that choke out native plants and impact wildlife.

Zebra Mussel

Characterized by its zebra-striped shell.

Can attach to surfaces and reproduce quickly, causing significant ecological and economic impacts.

Alters habitats by filtering large volumes of water, resulting in clearer water but reduced phytoplankton.

Causes fouling of water intakes and surfaces, increasing maintenance costs for water systems. invasive

spiny waterflea

Invasive zooplankton species found in freshwater lakes.

Characterized by a long tail spine and a body covered with spines.

Can reproduce rapidly, leading to large population outbreaks.

Competes with native zooplankton species for food resources.

Can affect the entire food web, impacting fish populations due to reduced food availability.

Lentic

Ponds, lakes Lakes, pondsStratification occurs Nutrients accumulate More eutrophication risk

Lotic

rivers streams, flowomg, High turbulence → higher DO Nutrients move downstream Organisms adapted to cling/flatten