Topic 4 - Water and aquatic food production

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116 Terms

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Domestic sewage

The most universal pollutant, consisting mainly of organic matter from households, including carbohydrates, proteins, fats, and pathogens.

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Industrial discharge

Wastewater from industries that varies in composition and may contain organic matter, toxic metals, or synthetic non-biodegradable compounds.

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Agricultural run-off

Water that carries pesticides, fertilizers, and organic material from farms, especially from intensive farming practices.

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Urban run-off

Polluted water resulting from rainwater accumulating pollutants from urban areas as it flows into nearby water systems.

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Landfill sites

Areas where waste is disposed of, potentially leading to leachates that contaminate groundwater or surface waters.

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Acid mine drainage

Pollution resulting from rainwater interacting with iron pyrite in mines, leading to acidic water that dissolves toxic metals.

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Eutrophication

The enrichment of waters with nutrients leading to excessive plant growth and subsequent depletion of oxygen in the water.

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Synthetic compounds

Man-made substances, often non-biodegradable, which can accumulate in the environment and have harmful biological effects.

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Bioaccumulation

The buildup of substances, such as toxic metals, within organisms over time.

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Biochemical oxygen demand (BOD)

A measure of the amount of dissolved oxygen used by microorganisms in breaking down organic material in water.

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Biotic index

A method used to assess water quality based on the diversity of living organisms in the water.

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Pathogens

Microorganisms such as bacteria and viruses, often found in sewage effluent, which can pose health risks if water is consumed.

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Suspended solids

Small particles in water that reduce light penetration and can smother aquatic organisms, affecting photosynthesis.

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Toxic metals

Heavy metals that, at high concentrations, can be harmful to aquatic life and may accumulate through the food chain.

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Organic pollution

Pollution resulting from organic materials like sewage and agricultural waste, which can deplete oxygen levels in water.

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Outfall pipes

Pipes used to discharge material, such as sewage or wastewater, directly into the sea or water bodies.

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Hot water discharge

Release of heated water from power stations that can elevate local water temperatures, impacting aquatic ecosystems.

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Invasive species

Non-native species introduced to new environments, often disrupting local ecosystems and causing ecological harm.

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Indicator species

Species used to assess the health of an aquatic environment based on their sensitivity to pollution levels.

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Leachates

Liquid that has percolated through waste and leached out various substances, potentially contaminating groundwater.

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Accidental discharges

Unintentional release of pollutants, such as oil or hazardous materials, into water systems.

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what percentage of earth is covered by water

70%

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what percentage of earths water salt water and fresh water

97% salt water, 3% fresh water

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where is freshwater stored (+how much percent)

  • 0.3% in lakes and rivers

  • 2.7% ice caps, ground water, lakes, soil water, atmospheric water, biota

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hydrological cycle

process whereby water is constantly recycled between sea, air and land

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storages in the water cycle

  • snow and ice

  • groundwater

  • lakes and rivers

  • oceans

  • atmosphere

    • gas = water vapour

    • liquid = water droplets

  • soil

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flows in the water cycle

  • precipitation

  • melting

  • interception

  • Infiltration

  • surface run offs

  • groundwater flow

  • percolation

  • evapotranspiration

  • evaporation

  • condensation

  • discharge

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Interception

process of interrupting the flow of water into streams

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Infiltration

physical process of moving water into soil (accumulates minerals and nutrients)

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percolation

movement of water through the soil (through gravity and capillary forces)

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evapotranspiration

processes by which water moves from the land surface to the atmosphere via evaporation and transpiration

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transpiration

the process of water movement through a plant and its evaporation from aerial parts, such as leaves, stems and flowers

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discharge

the volumetric amount of water carried by a body of water

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ocean currents play an important role in…

global energy distribution

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how are surface currents moved?

wind

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how are deep water currents moved?

oceanic conveyor belt

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upwellings

  • warm water can hold less salt than cold water

  • therefore warm water rises

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downwellings

  • cold water rises to replace the rising warm water

  • warm water replaces cold water

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El nino

above-average sea surface temperatures that periodically develop across the east-central equatorial Pacific

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La nina

periodic cooling of sea-surface temperatures across the east-central equatorial Pacific

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why do el nino and la nina occur?

  • result from interactions between the ocean surface and the atmosphere over the tropical Pacific

  • changes in the ocean surface temperatures affect tropical rainfall patterns and atmospheric winds over the Pacific ocean

  • which impacts the ocean temperatures and currents

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how often do el nina and el nino occur?

every 3-5 years

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water stress

when demand exceeds the available supply over a certain time period or when the quality of water restricts its use

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parameters of water stress

when supply is less than 1700 cubic meters/person/year (m3/person/year)

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water scarcity

water supplies fall below 1000 m3/person/year

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water scarcity issues

  • Growing population increases need for water and food

  • Climate change affecting precipitation rates and changing monsoons

  • Agricultural practices can produce high evaporation rates

  • Low water levels in many surface water sources

  • Aquifers being exhausted due to over pumping

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water scarcity large scale solutions

  • Build dams

  • Desalination

  • Rainwater harvesting

  • •Artificially recharged aquifers

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water scarcity small scale solutions

  • More efficient domestic use (low flow applications and faucets)

  • Grey water recycling

  • Rainwater harvesting

  • Drought resistant crops

  • Drip irrigation

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water degredation issues

  • Water Degradation Issues

  • Contamination of aquifers with arsenic, salt and other substances

  • Salinization of top solid due to high evaporation rates

  • Use of fertilizers and pesticides

  • Industrial release of pollutants

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Water Degradation Solutions

•Using organic farming methods

•Use highly selective pesticides

•Industry must remove pollutants from wastewater

•Regulate the temperature of water being released from cooling towers

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Main goal of a dam and reservoir system

  • Capture and store runoff

  • Release runoff as needed to control

  • Flood control

  • Fisheries

  • Hydropower

  • Supply irrigation water

  • Recreational, aesthetic and scenic value

  • Navigation

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What drives the hydrological cycle

solar radiation

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How does deforestation impact the hydrological cycle?

  • Reduces interception, allowing rainfall to directly impact the soil, increasing erosion

  • Speeds up surface run-off, reducing infiltration and percolation

  • Decreases transpiration, reducing local air moisture and rainfall, potentially causing drier climates

  • increasing evaporation

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How does urbanisation affect the hydrological cycle?

  • Replaces permeable surfaces with impervious materials, preventing infiltration and increasing surface run-off

  • Channels water into drainage systems, leading to higher river flow and flood risks

  • Polluted run-off from streets and roofs degrades water quality and aquatic ecosystems

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How does agriculture affect the hydrological cycle?

  • Excessive irrigation uses up water and makes soil salty due to evaporation.

  • Farm run-off carries fertilizers and pesticides into water, causing eutrophication

  • Livestock waste adds nutrients and organic matter to water, lowering oxygen levels and harming aquatic life

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what is the relationship between the hydrological cycle and ecosystem

Precipitation patterns determine ecosystem distribution and agricultural potential

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water security

The ability to ensure sustainable access to adequate quantities of safe, clean water for people, ecosystems, and agriculture

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what are the 2 types of water scarcity

  • physical scarcity

  • economic scarcity

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what factors impact water security?

  • Population growth

  • climate change

  • pollution

  • overuse

  • infrastructure

  • political/economic factors

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what is a water footprint

  • blue water (surface and groundwater)

  • green water (rainwater for crops)

  • grey water (water to dilute pollutants)

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what causes water stress?

  • Rapid urbanization

  • industrialization

  • overextraction of groundwater

  • pollution

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what are domestic water conservation techniques?

  • fixing leaks

  • using greywater for irrigation

  • rainwater harvesting

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What are some industrial water conservation techniques?

  • recycling water

  • adopting water-efficient technologies

  • implementing zero-liquid discharge systems

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What role do phytoplankton play in aquatic ecosystems?

form the foundation of aquatic food webs by converting sunlight and nutrients into organic matter

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What are the areas of highest aquatic productivity?

  • coastlines

  • shallow seas

  • upwellings

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aquaculture

The farming of aquatic organisms to meet increasing demand for seafood

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pros of aquaculture

  • increased food supply

  • economic benefit (job opportunities)

  • efficient use of resources (max sustainable yield, less water and land than lifestok farming

  • reduces overfishing of wild species

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cons of aquaculture

  • loss of habitat

  • pollution

  • spread of diseases

  • introduction of non-native species, that competes with wild species

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fishing methods

  • trawler fishing

  • purse-seine net

  • long-lining

  • drift net

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Trawler fishing

fishing vessel drags a trawl through water behind one or more trawlers

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trawler fishing evaluated (selectivity, sea bed damage, yield)

  • selectivity = medium

  • sea bed damage = high

  • yield = high

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purse-seine net evaluated (selectivity, sea bed damage, yield)

  • selectivity = low

  • sea bed damage = none

  • yield = high

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long-lining evaluated (selectivity, sea bed damage, yield)

  • selectivity = high

  • sea bed damage = none

  • yield = medium

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long-lining evaluated (selectivity, sea bed damage, yield)

  • selectivity = high

  • sea bed damage = none

  • yield = low

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what is water pollution?

water pollution occurs when harmful substances contaminate water, degrading the quality of the water

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types of water pollution

  • inland and coastal pollution

  • marine based

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inland and coast polution

  • domestic sewage

  • industrial discharge

  • agricultural run off

  • urban run off

  • land development

  • landfill sites

  • accidental discharges

  • acid mine drainage

  • atmospheric input

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marine based

  • materials dumped at sea

  • shipping activities

  • exploitation of resources

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effects of water pollution

  • organic pollution

  • inorganic plant nutrients

  • eutrophication

  • toxic metals

  • synthetic compounds

  • inert suspended solids

  • thermal pollution

  • oil

  • pathogens

  • plastic debris

  • light pollution

  • noise pollution

  • invasive species

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assessing water quality (physical and chemical parameters)

  • Ph

  • temperature

  • suspended solids

  • total dissolved solids and conductivity

  • dissolved oxygen (DO2)

  • Biochemical oxygen demand (BOD)

  • Nutrients

  • Metals

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assessing water quality (biological parameters)

  • kick sampling of macro-invertebrates

  • biotic index

  • microbial test

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measuring suspended solids

  • filtering known volume of water sample using pre-weighed filter paper

  • drying out the filter paper and collected residue

  • weighing the dried filter paper and residue

  • calculate the weigh of the dried residue (final weigh of filter paper - initial weight of the filter paper) in mg/l

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total dissolved solids (TDS) what does it measure?

indicates the amount of salts present, geology and type of effluent

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total dissolved solids (TDS) how is it measured?

measured indirectly using conductivity meter

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increasing levels of TDS …

higher conductivity readings

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turbidity meter what does it measure?

amount of light scattered by particles in the water

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secchi disk what does it measure?

water transparency

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the greater the amount of suspended solids …

the lower the light transparency of the water

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Dissolved Oxygen (DO2) how is it measured?

  • filling bottle with water sample

  • add reagents to sample to fix oxygen by converting it to acid

  • titrating the sample in which reagent is gradually added to neutralize the acid

  • amount of reagent used to neutralize the acid is used to calculate the amount of dissolved oxygen levels

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biochemical oxygen demand (BOD) what does it measure?

the amount of dissolved oxygen used to breakdown the organic material in a given volume of water through aerobic activity

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biochemical oxygen demand (BOD) how is it measured?

  • initial dissolved oxygen reading of the sample is taken in mg/l

  • one litre bottle is filled with the sample and sealed

  • bottle is incubated in the dark at 20C for 5 days

  • dissolved oxygen levels are measured again

  • difference between the initial and final oxygen readings is BOD5

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BOD5 < 2 mg/l

unspoilt water

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BOD5 = 20mg/l

badly polluted water

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nutrients test what does it measure

measures amount of nutrients such as nitrates, phosphates and silica

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nutrients test how is it measured

  • measured using chemical analysis methods

  • on-site testing kits differ but rely on nutrients reacting with reagents to produce a color change

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limitations to testing for physical and chemical parameters

  • provides information for that specific sample at that particular time

  • does not indicate whether the water is safe for drinking

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why is examination of only physical and chemical parameters not sufficient to determine if the water is safe to use

  • pathogens may be present in the water

  • pollutants may be washed away even though they may have severely damaged ecosystem

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why are macro-invertebrates used for biological monotoring

  • stationary, representative of the environment they are found in

  • relatively long life history providing summary of conditions over time

  • abundant

  • relatively easy to sample

  • consists of diverse groups of organisms

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biological monitoring what is it?

using biological organisms to indicate whether water quality decline and whether there have been episodes of pollution between samples

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kick sampling

bottom of stream is agitated by kicking the riverbed, organisms are swept into net for analysis