Enviro Biology

ecosystem ecology

the study of how living organisms interact with each other and the physical environment (helps understand human activities e.g. wastewater discharge and climate change)

1st law of thermodynamics

organisms do not create themselves, energy flows through ecosystems and is transformed from one form to another

2nd law of thermodynamics

only a small portion of energy is passed from one trophic level to the next because organisms use much of it for respiration, movement and growth

transformation of light to chemical energy

the process where plants convert solar energy to chemical energy through photosynthesis but the conversion is inefficient because some light is reflected by/passes through leaves or misses chloroplasts

ecological inefficiency

only 10% of energy at one trophic level is transferred to the next trophic level, while the rest is lost through respiration, heat and metabolic processes

food web

a microbial interaction network where microorganisms mainly exchange dissolved organic molecules and nutrients released by other microbes, rather than consuming entire cells

bioaccumulation

the gradual buildup of contaminants within an organism over time through repeated ingestion or absorption faster than the substance can be removed. important when assessing long term impacts of pollutants in organisms

biomagnification

the increase in concentration of persistent contaminants as they move up the food chain. causes highest levels in top predators

plants and stormwater

stormwater contains dissolved nutrients (nitrogen, phosphorus) collected from atmosphere and surrounding environmental

algal bloom events

driven by environmental conditions created by human activities such as excess nutrients in wastewater or fertilisers. warm temperature, sunlight and stagnant water further promotes growth

biogeochemical cycles

natural movement and recycling of elements (carbon, nitrogen, phosphorus, sulfure) between the atmosphere, water, soil and living organisms

reservoir

a storage location where a substance is held for a period of time

flux

the rate at which a substance moves between reservoirs such as CO2 exchange between atmosphere and plants

source

a location that releases more material than it absorbs

sink

a location that absorbs more material than it releases

organic carbon

carbon contained within living organisms or compounds produced by living systems e.g. carbohydrates and fossil fuels

inorganic carbon

carbon found in non living form such as CO2, carbonate minerals and dissolved CO2 in water

redox reaction

chemical reaction involving the loss (oxidation) or gain (reduction) of hydrogen. controls processes in wastewater treatment and contaminant breakdown

carbon reservoir

carbon storage e.g. sedimentary rocks such as limestone, the oceans and the atmosphere. it tells us about carbon cycling, human impacts and carbon sequestration potential (CO2 capture)

respiration

biological process where organisms break down organic compounds using oxygen to release energy. water and CO2 are byproducts

fermentation

anaerobic process where microorganisms break down organic matter without oxygen to produce energy

organic carbon decomposition

the breakdown of organic matter by decomposer organisms. organic matter entering the food web is partly converted to new biomass and decomposers further break dead organisms down into simpler compounds

carbon transformation in water

atmospheric CO2 dissolves into oceans where it mainly exists as inorganic carbon species. carbon is absorbed by autotrophs through photosynthesis and absorbed by aquatic organisms

abiotic carbon transformation

non living physical and chemical processes that convert carbon into different forms over long timescalesli

limestone formation

when calcium carbonate from shells and marine organisms is deposited and compacted into sedimentary rock

fossil fuel formation

when dead organic matter is subjected to high temperature and pressure converting it into coal, oil and natural gas

nitrogen fixation

biological conversion of N2 into ammonia or ammonium. Plants cannot directly fix N2, only certain nitrogen-fixing bacteria possess enzymes required for this processn

nitrification

an aerobic process where ammonia is oxidised first into nitrite then nitrate. occurs through special bacteria and is essential in wastewater treatment for removing toxic ammonia from water

denitrification

nitrate is converted into N2, returning nitrogen to the atmosphere. this occurs when oxygen is limited and microorganisms use nitrate as an alternative electron acceptor. removes excess nitrogen from wastewater and prevents eutrophication

assimilation

the uptake of nutrients such as nitrogen, phosphorus or carbon into living organisms to form biomass. plants do this through soil and water, animals do this through digestion

urea hydrolysis

the breakdown of urea into ammonia and CO2 through enzyme urease. recycles nitrogen from waste back into ecosystems

decomposition/ammonification

the microbial breakdown of organic nitrogen in dead organisms into ammonia, recycling nitrogen into environment

best conditions for nitrification

high dissolved oxygen (aerobic), warm and moist with adequate ammonia supply and low organic matter

organisms enriched by nitrification

ammonia oxidising bacteria (convert ammonia to nitrite) and nitrite oxidising bacteria (convert nitrite to nitrate)

phosphorus cycle

movement of phosphorus through rocks and soil. unlike carbon and nitrogen, phosphorus does not commonly exist as gas so cycle is slower

inorganic phosphorus

exists as phosphate minerals or dissolved phosphate ions in soil and water

organic phosphorus

phosphorus incorporated into living organisms such as DNA and cell membranes

unbalanced phosphorus cycle

human activities such as mining and fertiliser add phosphorus to ecosystems faster than nature systems can remove it which can disrupt ecosystem balance

eutrophication

the excessive enrichment of water bodies with nutrients causing rapid algae growth and poor water qualityli

limiting nutrient

biological growth is controlled by the nutrient in shortest supply relative to demand (usually phosphorus)

oxygen depletion

dead algae are decomposed by bacteria, which use up dissolved oxygen and can cause hypoxia

oligotrophic lake

nutrient poor, low algal growth, high dissolved oxygen and clear water

mesotrophic

moderate nutrient levels and intermediate productivity

eutrophic

nutrient rich, highly productive, often experience algal blooms and may suffer from oxygen depletion

biodegradability

ability for organic matter to be broken down my microorganisms into simpler substances. BOD/COD - high means most matter can be degraded

biocementation

processes that promote calcium carbonate precipitation which stabilises soils

biological oxygen demand (BOD)

the amount of dissolved oxygen that microorganisms need to biologically break down biodegradable organic matter in water

chemical oxygen demand (COD)

the amount of oxygen required to chemically oxidise all oxidisable material using strong chemical oxidants (measures both biodegradable AND non-biodegradable organics)

extremophiles

microorganisms that thrive in extreme environmental conditions that would normally be harmful to most life forms (e.g. high/low temperature, pH, pressure, oxygen levels)

microbial growth

the increase in the number of microorganisms through cell division when environmental conditions are favourable

metabolism

the sum of all chemical processes of the cell

catabolism

the break down of nutrients to obtain energy and building blocks and restore reducing power

anabolism

biosynthesis of more complex molecules from precursor molecules using stored energy

NAD+

an empty shuttle/battery that can carry electrons. when it picks up electrons it becomes NADH

reduction (in cells)

gain of electrons to form NADH which forms an energy rich electron carrier

catabolism process

cell breaks down food, electrons are removed from food, NAD+ picks up electrons. food gets oxidised, NAD+ reduced to NADH

ATP

main energy carrying molecule used by cells to store and transfer energy for biological processes. constantly being made and used

NADH

donates electrons to release energy and produce ATP

microbial metabolism conditions

water, nutrients, energy source, electron acceptor

autotrophs

organisms that make their own food using inorganic substances like CO2

heterotrophs

organisms that get food and carbon by consuming other organisms or organic matter

phototrophs

organisms that get energy from light

chemotrophs

organisms that get energy from chemical reactions

cellular respiration

cells break down organic molecules such as glucose to release energy and produce ATP

glycolysis

respiration starts by breaking down glucose into smaller molecules. some ATP and NADH made but no oxygen used

Krebs cycle

generates some ATP and lots of NADH. produces CO2 but does not directly involve oxygen

electron transport system

electrons from NADH are passed along a chain of proteins, and the energy released is used to make lots of ATP. NADH is oxidised to regenerate NAD+

anaerobic respiration

when organisms respirate using alternative terminal electron acceptors besides O2

fermentation

ETC pathway is not possible so less ATP is produced. NAD+ regenerated but some CO2 and other products formed as well

chemotrophs

organisms that obtain energy from chemical reactions

chemoheterotrophs

organisms that obtain energy from chemicals and obtain carbon from organic compounds

chemoautotrophs

organisms that obtain energy from chemical reactions and obtain carbon from CO2

phototrophs

organisms that obtain energy from light

photoheterotrophs

organisms that obtain energy from light and obtain carbon from organic compounds

photoautotrophs

organisms that obtain energy from light and obtain carbon from CO2

pyschrophiles

microorganisms found in icy regions

hyperthermophiles

microorganisms found in extremely hot regions

halophiles

microorganisms that require high salt concentrations to grow and survive

halotolerant

microorganisms that can tolerate high salt concentrations but does not require salt for growth

lag phase

interval between inoculation of a culture and beginning of growth. time needed for biosynthesis of new enzymes to meet new culture requirements

exponential phase

exponential cell growth (cells double every generation)

stationary phase

growth rate = death rate. net growth rate is zero. environmental stress due to depletion of an essential nutrient or accumulation of waste products

death phase

new cells deplete nutrients which worsens environmental conditions. death rate > growth rate

Monod model

microbes grow as fast as possible when there is a lot of available nutrients, adding more food does not increase growth. when nutrients run out, growth decreases

pathogen risk

can invade the body causing infectious diseases

organic matter risk

can create dead zones where excess is discharged to aquatic bodies and promotes growth of heterotrophic bacteria, which leads to oxygen depletion and death of other aquatic species

nutrient risk

partially treated sewage leads to eutrophication

primary treatment (WWTP)

reduce suspended solid and organic matter before biological treatment, heavy solid settle as sludge while oils and grease float to top and skimmed off

secondary treatment (WWTP)

use microorganisms to biologically break down dissolved carbon, nitrogen and phosphorus. remove biodegradable organic matter and reduce BOD

tertiary treatment (WWTP)

further disinfect water to avoid release of pathogens

sludge treatment (WWTP)

biologically remove carbon, reduce sludge volume and stabilise organic matter

organic carbon removal (WWTP)

use water with heterotrophic microorganisms (activated sludge) to break down compounds through respiration. some carbon comes biomass for new sludge

nitrification in WWTP

chemoautotrophic bacteria oxidise ammonia in aerobic tank, different bacteria converts to N2 in anoxic tank, some nitrogen becomes part of biomass

enhanced biological phosphorus removal (EBPR)

in aerobic tank, PAOs take in carbon and release phosphorus, in aerobic tank, PAOs use store carbon and absorb large amounts of phosphorus. sludge is removed

sludge process

large organic compounds in sludge are broken down to produce Volatile Fatty Acids (VFAs). This is converted into biogas which produces methane CO4, CO2 and stabilised sludge (anaerobic biomass)