4.4 Water pollution

what are some examples of types of aquatic pollutants

organic material, inorganic plant nutrients, toxic metals, synthetic compounds, suspended solids, hot water, oil, radioactive pollution, pathogens, light, noise, invasive species

what types of parameters can be used to directly test the quality of aquatic systems

pH, temperature, suspended solids, metals, nitrates, phosphates

what are some negative results of biodegradation of organic materials

it uses oxygen which can lead to anoxic conditions and subsequent anaerobic decomposition which leads to formation of methane, hydrogen sulphide and ammonia

what is biochemical oxygen demand

a measure of the amount of dissolved oxygen required to break down the organic material in a given volume of water through aerobic biological activity

what is biochemical oxygen demand used to measure

indirectly measures the amount of organic matter within a sample

what does a biotic index measure

indirectly measures pollution by assaying the impact on species within the community according to their tolerance, diversity and relative abundance

when can eutrophication occur

when lakes, estuaries and coastal waters receive inputs of nutrients which result in an excess growth of plants and phytoplankton

when do dead zones in oceans and freshwater occur

when there is not enough oxygen to support marine life

what is water pollution

the contamination of bodies of water by pollutants either directly or indirectly

how many people are killed by water pollution every day

over 14,000

how many people do not have access to clean, safe drinking water

nearly half a billion people

what are the four main types of water pollution

anthropogenic or natural, point source or non point source, organic or inorganic, direct or indirect

what are the effects of sewage, animal waste, biological detergents and food processing waste

eutrophication and smell

what is the effect of pesticides from agriculture

loss of biodiversity

what are the effects of chemicals from industry

may be carcinogenic, growth-promoting hormones

what are the effects of pathogens

disease

what is the effect of invasive species

decimates indigenous species

what are the effects of nitrates and phosphates

eutrophication, changes in biodiversity

what is the effect of heavy toxic metals

bioaccumulation and biomagnification in food chains, poisonous

what is the effect of hot water

changes physical property of water, kills fish, changes biodiversity

what is the effect of oil

floats on surface, contaminates seabirds, reduces oxygen levels

what is the effect of radioactive materials

radiation sickness

what is the effect of light and noise

disrupts turtle nesting sites, upsets whale navigation, change plant growth, upset bird cycles

what is the effect of suspended solids

damages corals and filter feeders

what is the effect of solid domestic waste and debris

can suffocate and cause starvation

what are some sources of freshwater pollution

agricultural run-off, sewage, industrial discharge, solid domestic waste

what are some examples of marine pollution

rivers, pipelines, the atmosphere and human activities at sea, both operational and accidental discharges

what is an indicator species

plants and animals that show something about their presence, absence, abundance or scarcity

why are indicator species early warning signs that something may have changed in an ecosystem

they are most sensitive to change

what is a biotic index

a scale that gives a measure of the quality of an ecosystem by the presence and abundance of the species living in it

why are invertebrates used to estimate levels of pollution

they are sensitive to decreases in oxygen concentration in water, caused by the action of aerobic bacteria as they decompose organic matter

what is eutrophication

when excess nutrients are added to an aquatic ecosystem, it can be a natural process but anthropogenic eutrophication is more common

what happens when eutrophication is severe

it results in dead zones where there is not enough oxygen to support life

what happens in less severe cases of eutrophication

biodegradation of organic material uses up oxygen which can lead to anoxic conditions and then anaerobic decomposition, this can release methane, hydrogen sulphide and ammonia which are all toxic gases

what are some easily noticeable effects of eutrophication

leads to unsightly rivers, ponds and lakes covered by green algal scum and duckweed, give off foul-smelling gases like hydrogen sulphide

what are some less noticeable effects of eutrophication

oxygen deficient water, loss of biodiversity and shortened food chains, death of higher plants, death of aerobic organisms, increased turbitity

where do the excess nutrients in eutrophication come from

detergents, fertilizers, drainage from intensive livestock rearing units, sewage, increased erosion of topsoil into the water

explain the process of eutrophication

fertilizers wash into the river or lake, high levels of phosphate in particular allow algae to grow faster, algal blooms form that block out light to plants beneath them, which die, more algae mean more food for the zooplankton and small animals that feed on them, they are food to fish which multiply as there is more food so there are then fewer zooplankton to eat the algae, algae die and are decomposed by aerobic bacteria, but there is not enough oxygen in the water so,soon, everything dies as food chains collapse, oxygen levels fall lower, dead organic material forms sediments on the lake or river bed and turbidity increases, eventually all life is gone and the sediment settles to leave a clear blue lake

where is the largest dead zone in the USA

the gulf of Mexico

what is the dead zone in the Gulf of Mexico caused by

excess nitrates and phosphates from the Mississippi River basin agriculture

what is one solution proposed to solve the dead zone in the gulf of Mexico

a strategy of nutrient trading as a voluntary marked based reduction of nutrient use, it allows those that can reduce nutrients at low cost to sell credits to those facing higher cost nutrient reduction options, this allows pollution sources to meet their targets in a cost effective manner

when do algal blooms look red

if the phytoplankton are a specie sof dinoflagellate

why can red algal blooms be dangerous

they produce toxins, which kill fish and accumulate in shellfish, which can make humans seriously ill

what does eutrophication lead to in slow moving water bodies

a series of damaging changes which severely reduces biodiversity

what is the result of eutrophication in fast moving water

a temporary reduction in biodiversity downstream which can be followed by a recovery and restoration of clean water

what is an example of altering the human activity producing pollution

ban or limit detergents with phosphates, use ecodetergents with no phosphates or new technology in washing machines, plant buffer zones between the fields and water courses to absorb the excess nutrients, stop leaching of slurry or sewage from their sources, educate farmers about more effective timing for fertilizer application

what is an example of regulating and reducing the pollutants at the point of emission

treat wastewater before release to remove phosphates and nitrates, divert of treat sewage waste effectively, minimize fertilizer dosage on agricultural lands or use organic matter instead

what is an example of clean up and restoration of eutrophication

pumping air through the lakes, dredging sentiments with high nutrient levels from the river and lake beds, remove excess weeds physically or by herbicides and algicides, restock ponds or water bodies with appropriate organisms