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Questions and Answers
What effect does a steeper ground gradient have on overland flow?
What effect does a steeper ground gradient have on overland flow?
What characterizes a gaining stream?
What characterizes a gaining stream?
What is a primary concern with groundwater abstraction?
What is a primary concern with groundwater abstraction?
Which statement accurately describes aquifers?
Which statement accurately describes aquifers?
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How can surface water catchments differ from groundwater catchments?
How can surface water catchments differ from groundwater catchments?
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What is the role of vegetative cover in water infiltration?
What is the role of vegetative cover in water infiltration?
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In what way can better groundwater management address water shortages?
In what way can better groundwater management address water shortages?
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What describes an unconfined aquifer?
What describes an unconfined aquifer?
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What is the role of hydrogen bonds in water?
What is the role of hydrogen bonds in water?
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What concept explains why water can absorb large amounts of heat without significant temperature change?
What concept explains why water can absorb large amounts of heat without significant temperature change?
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How does the presence of solutes affect the boiling and freezing points of water?
How does the presence of solutes affect the boiling and freezing points of water?
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Which property of water is responsible for insects being able to walk on its surface?
Which property of water is responsible for insects being able to walk on its surface?
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What is the primary outcome of the transpiration process in plants?
What is the primary outcome of the transpiration process in plants?
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What is a significant contributor to climate variability and extreme weather events?
What is a significant contributor to climate variability and extreme weather events?
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What phenomenon affects climate and the water cycle every 3-6 years?
What phenomenon affects climate and the water cycle every 3-6 years?
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Which water property allows it to be an effective coolant?
Which water property allows it to be an effective coolant?
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Why does water play a crucial role in homeostasis?
Why does water play a crucial role in homeostasis?
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What are the two primary forms of water precipitation?
What are the two primary forms of water precipitation?
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How does deforestation impact river flow rates?
How does deforestation impact river flow rates?
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What effect does urban development have on local river systems?
What effect does urban development have on local river systems?
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Which of the following is a consequence of fluvial flooding?
Which of the following is a consequence of fluvial flooding?
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How do meandering rivers typically change over time?
How do meandering rivers typically change over time?
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What role does vegetation along riverbanks play?
What role does vegetation along riverbanks play?
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What effect does temperature have on dissolved oxygen levels in water?
What effect does temperature have on dissolved oxygen levels in water?
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What characterizes oligotrophic lakes?
What characterizes oligotrophic lakes?
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What is a primary factor contributing to the increase of total dissolved solids (TDS) in surface waters?
What is a primary factor contributing to the increase of total dissolved solids (TDS) in surface waters?
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What is the significance of the thermocline in lakes?
What is the significance of the thermocline in lakes?
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Which human activity significantly contributes to eutrophication?
Which human activity significantly contributes to eutrophication?
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What is the primary source of suspended sediments in surface waters?
What is the primary source of suspended sediments in surface waters?
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How do smaller sediment particles move in a river system?
How do smaller sediment particles move in a river system?
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What is the main purpose of catchment-wide solutions in river management?
What is the main purpose of catchment-wide solutions in river management?
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What characterizes Well B in relation to the aquifer?
What characterizes Well B in relation to the aquifer?
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What type of rocks typically make the best aquifers?
What type of rocks typically make the best aquifers?
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Which statement accurately describes hydraulic head?
Which statement accurately describes hydraulic head?
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What is one factor that influences the primary productivity of aquatic ecosystems?
What is one factor that influences the primary productivity of aquatic ecosystems?
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Which type of diversity refers to the change in species diversity across habitats or ecosystems?
Which type of diversity refers to the change in species diversity across habitats or ecosystems?
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Which zone of a lake receives abundant sunlight and supports plant life?
Which zone of a lake receives abundant sunlight and supports plant life?
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What is a key consequence of eutrophication in aquatic ecosystems?
What is a key consequence of eutrophication in aquatic ecosystems?
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In terms of nutrient cycling, how does nutrient spiraling differ?
In terms of nutrient cycling, how does nutrient spiraling differ?
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What does hypoxia refer to in aquatic environments?
What does hypoxia refer to in aquatic environments?
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Which of the following statements is true about invasive species?
Which of the following statements is true about invasive species?
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What is the ecological role of primary producers in aquatic ecosystems?
What is the ecological role of primary producers in aquatic ecosystems?
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Which type of respiration involves the use of dissolved oxygen by organisms in aquatic ecosystems?
Which type of respiration involves the use of dissolved oxygen by organisms in aquatic ecosystems?
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What limitation does nitrogen impose in many ecosystems?
What limitation does nitrogen impose in many ecosystems?
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What is the impact of biodegradable materials on the environment?
What is the impact of biodegradable materials on the environment?
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Which type of pollution source is characterized by a single identifiable source?
Which type of pollution source is characterized by a single identifiable source?
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How does intermittent pollution primarily affect ecosystems?
How does intermittent pollution primarily affect ecosystems?
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What was one of the consequences of the Deepwater Horizon oil spill?
What was one of the consequences of the Deepwater Horizon oil spill?
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What process is stimulated by nutrient overloads in aquatic systems, leading to oxygen depletion?
What process is stimulated by nutrient overloads in aquatic systems, leading to oxygen depletion?
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What are endocrine disruptors known to affect?
What are endocrine disruptors known to affect?
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What is a major consequence of heavy metals in aquatic environments?
What is a major consequence of heavy metals in aquatic environments?
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Which of the following is NOT a category of infectious disease related to water?
Which of the following is NOT a category of infectious disease related to water?
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Which action is NOT recommended for cleaning up pollution?
Which action is NOT recommended for cleaning up pollution?
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What adverse effect does marine acidification have on marine life?
What adverse effect does marine acidification have on marine life?
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What is the best practicable environmental option (BPEO) focused on?
What is the best practicable environmental option (BPEO) focused on?
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How do inert solids primarily affect water quality?
How do inert solids primarily affect water quality?
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What is a common effect of natural disasters on water bodies?
What is a common effect of natural disasters on water bodies?
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Study Notes
Water on earth
- 73% of Earth’s surface is covered by water.
- Canada possesses 7% of the world's renewable freshwater supply.
Properties of water
- All life relies on water.
- H2O is the most abundant molecule found in cells.
- Many chemical reactions in nature occur with molecules dissolved in water.
- A solution comprises solutes dissolved in a solvent.
- Water's polarity makes it an effective solvent, capable of dissolving various molecules.
Polar covalent bonds
- The unequal distribution of electrons in water molecules creates a polarity, leading to a difference in charge across the molecule.
Hydrogen bonds
- Hydrogen atoms from one polar molecule are attracted to electronegative atoms of another polar molecule.
- While individually weak, these bonds collectively contribute to strong interactions.
Cohesion
- Cohesion refers to the attraction between particles of the same substance, explaining why water molecules stick together.
- It leads to surface tension, measured by the strength of the water's surface.
- This surface tension allows some insects to walk on water.
Adhesion
- Adhesion is the attraction between two different substances.
- Water forms hydrogen bonds with various surfaces like glass, soil, plant tissues, and cotton.
- Capillary action occurs when water molecules pull each other along thin glass tubes.
- This mechanism plays a role in the transpiration process, where plants draw water from the soil.
High specific heat
- Specific heat refers to the amount of heat required to raise or lower the temperature of 1 gram of a substance by 1 degree Celsius.
- Water resists temperature changes, both for heating and cooling.
- It can absorb or release significant amounts of heat energy with minimal actual temperature alterations.
High heat of vaporization
- Heat of vaporization refers to the energy needed to convert 1 gram of a substance from liquid to gas.
- Hydrogen bonds must break for water to evaporate.
- As water evaporates, it carries away substantial heat, resulting in a cooling effect.
Water in 3 states of matter
- State changes in water involve energy input or release.
- Water remains stable in its liquid form.
- The freezing and boiling points of a solution are influenced by dissolved solutes.
- Adding solutes to water lowers the freezing point and raises the boiling point.
Homeostasis
- Homeostasis represents the ability to maintain a steady state despite fluctuating conditions.
- Water plays a crucial role in this process due to its: insulating properties, resistance to temperature changes, universal solvent capabilities, cooling effect, and ability to insulate frozen lakes against temperature extremes.
Water shapes landscapes
- Weathering, erosion, and transportation of materials are processes influenced by water.
- Water has shaped our landscapes.
- Water freezing between rocks can create pressure, leading to splitting and further weathering.
Water uses
- Essential for sustaining life.
- Serves as an industrial cooling agent.
- Used in power generation.
- Holds cultural and religious significance.
Agriculture
- Domestication of plants and animals led to the development of irrigation systems.
- Human settlements often emerged near reliable water sources.
- Alterations to water flow have resulted from agricultural practices.
Global water resources
- The water cycle involves a constant exchange of water between the atmosphere, land, and oceans through processes such as evaporation, transpiration, and precipitation.
- Evaporation rates are driven by solar radiation.
- Transpiration is the movement of water from the soil to the atmosphere through plants.
Water and energy
- The water cycle is interconnected with the global energy budget.
- Water vapor is a greenhouse gas, contributing significantly to the natural greenhouse effect.
- Differences in solar radiation across latitudes drive atmospheric and oceanic circulation, influencing climate and weather patterns.
Precipitation
- Precipitation encompasses all liquid and frozen forms of water, primarily rain and snow.
- Most of the water evaporating from the ocean returns to the ocean as precipitation.
- Approximately 40% of precipitation on land originates from water vapor transported from the ocean.
Climate variability and change
- The water cycle exhibits variation spatially and temporally.
- Extreme weather events can be linked to disruptions in normal air flow patterns.
- Research suggests human contributions to increased extreme weather events.
Multi-annual timescales
- The El Niño Southern Oscillation (ENSO) affects climate in extensive regions worldwide.
- Occurring every 3-6 years, ENSO intensity varies and can affect climate and the water cycle globally.
Land management and the water cycle
- Direct impacts of land management on the water cycle include dam construction, water extraction, and modifications to river channels.
- Equatorial rivers generally exhibit regular flow regimes influenced by seasonal rainfall patterns.
Impacts of land management on river flow
- Significant alterations to river flow can occur due to various human activities.
- Dams alter natural river regimes.
- Deforestation reduces transpiration, leading to increased flow rates.
- Agricultural practices can impact soil infiltration.
- Urban development reduces infiltration capacity, increasing the risk of downstream flooding.
Impacts of land management on river flow
- Sustainable urban drainage systems aim to mitigate the impacts of urban development on river flow.
- This involves incorporating permeable surfaces, discharge pipes into ponds or channels, dedicated stormwater spaces, and parks near rivers.
Flooding
- Flooding is a natural phenomenon that can bring nutrients to terrestrial soils.
- However, it can also devastate residential areas.
- Fluvial flooding occurs when heavy rainfall causes concentrated overland flow, inundating an area.
- Coastal flooding arises from high tides, storm surges, and tsunamis.
- Floodplains are low-lying areas prone to flooding but often favored for human settlements due to fertile soils and proximity to waterways.
River channel dynamics
- Rivers change over time, typically forming branching networks.
- Their shapes are shaped by topography and geology.
- River channels can vary in shape, including braided, meandering, and straight.
River cross-sections
- River cross-sections generally become larger downstream, enhancing their water-carrying capacity.
- Vegetation along riverbanks can influence the shape through its roots.
- Water velocity tends to be slower near riverbanks, leading to sediment deposition.
- Helicoidal flow occurs in river bends, with faster water on the outer banks causing erosion, while slower water on the inner banks deposits sediment.
Sediment transport
- Suspended sediment refers to particles less than 1 mm wide, transported within the water column.
- Bedload is sediment transported along the riverbed through rolling, sliding, or hopping movements.
- Finer particles are preferentially transported downstream, while larger sizes tend to be found upstream.
- This natural sorting leads to a size gradation of sediments along the river.
Surface water quality
- Surface waters encompass various bodies like rivers, lakes, estuaries, and wetlands, each with different flow rates and characteristics.
Surface water sources
- Runoff, groundwater, and discharges contribute to surface water.
- Groundwater replenishment increases during periods of low flow, contributing to solutes and sediment levels.
- The amount of solutes and sediment varies depending on the pathway, with groundwater flow typically resulting in higher concentrations.
- Water chemistry is influenced by geology, vegetation, and hydrological processes.
Waste disposal
- Waste disposal can create conflicts with drinking water usage.
- A significant portion of municipal and industrial wastewater is discharged without treatment, resulting in pollution.
- These pollutants pose risks to human health and the environment.
- Heavily populated areas and regions with rapid economic growth are particularly vulnerable to water pollution.
Dissolved inorganic substances
- Minerals are typically found in the form of ions or colloids.
- Some minerals exhibit high solubility, while others attach to suspended sediments.
- TDS (Total Dissolved Solids) is the sum of all dissolved solutes, including silica.
- Dissolved inorganic substances significantly affect aquatic ecosystems, impacting water quality and the health of organisms.
Hydrogen ions (H+)
- Abrupt changes in pH can be detrimental to aquatic organisms.
- Most aquatic ecosystems maintain pH levels between 6.5 and 9.0.
- Significant deviations outside this range can negatively impact aquatic life.
- Metals exhibit higher solubility and thus higher toxicity at lower pH levels.
Suspended sediment
- Suspended sediment includes soil particles, algae, plankton, and microbes.
- Sources include soil erosion, water discharges, and runoff.
- In lakes, decaying matter and bottom-feeding fish help regulate suspended sediments.
- Excessive sediment can block sunlight, hinder photosynthesis, lower dissolved oxygen levels, increase water temperature, and enhance turbidity, which obstructs light penetration.
Dissolved gases - O2 and CO2
- Dissolved oxygen (DO) is a key indicator of water health.
- DO levels typically range from 0 to 18 mg/L.
- Fish require DO levels above 9 mg/L, while levels below 5 mg/L can stress fish.
- DO levels below 1-2 mg/L can kill fish within hours.
- The concentration of dissolved gases increases with pressure and decreases with temperature.
Organic substances
- Organic substances are carbon-based compounds.
- DOM (Dissolved Organic Matter) and DOC (Dissolved Organic Carbon) are part of the carbon cycle and primary food sources for aquatic food webs.
- Wastewater discharges, livestock farming, and urbanization contribute to elevated organic substance levels in water bodies.
Temperature
- Temperature significantly influences biological activity in aquatic ecosystems.
- Organisms have preferred temperature ranges.
- Mortality rates increase when temperatures deviate from these ranges.
- Stratification occurs in lakes, with alternating periods of vertical mixing.
- Temperature changes can alter the concentration of metals, influencing their availability and potential toxicity.
Trophic status
- Trophic status is determined by factors like phosphorus, chlorophyll, and transparency, which provide insights into nutrient levels and the balance of aquatic ecosystems.
- Eutrophication occurs when water bodies are enriched with nutrients, typically phosphorus in freshwater systems and nitrogen in marine systems.
- Eutrophication disrupts the ecological balance, favoring phytoplankton growth over other organisms.
- While naturally occurring, eutrophication is often amplified by human activities.
Temporal variations in surface water chemistry
- Surface water chemistry exhibits temporal variations.
- Changes in hydrological flow paths due to storms deliver varying sources and amounts of solutes, resulting in fluctuations in water chemistry.
- Diurnal variations in water chemistry occur in tropical regions, with heavy downpours contributing to surface overland flow.
Groundwater steam interactions
- The interaction between groundwater and streams depends on the relative heights of the water table and streambed.
- Gaining streams occur when groundwater contributes to stream flow, indicating a higher water table than the streambed.
- Losing streams occur when water from the stream recharges groundwater, indicating a lower water table than the streambed.
Groundwater management
- Groundwater catchments are defined areas with specific inflows and outflows of water.
- Surface water catchments can differ from groundwater catchments due to geological variations.
- Water balance evaluations assess changes in groundwater storage over time.
- Groundwater management strategies include limiting groundwater abstraction, implementing integrated catchment management, and considering the environmental consequences of abstraction.
Groundwater resources of the world
- Groundwater distribution is heterogeneous.
- Geological conditions and climate affect regional groundwater supplies.
- Some argue that improved groundwater management could address water shortages.
- Access to and the means to exploit groundwater resources vary, posing challenges for equitable access.
Aquifers
- An aquifer is a geological stratum containing water and allowing water movement within it.
- Aquifers are typically characterized by porosity and permeability.
Confined and unconfined aquifers
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Unconfined aquifers are directly connected to the surface, while confined aquifers are separated from the surface by an impermeable layer.### Groundwater
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Confined aquifers are under pressure, water rises above the top of the aquifer
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Artesian wells occur when the piezometric surface is above ground level, causing water to overflow naturally
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Sedimentary rocks make the best aquifers due to their pore space
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Igneous and metamorphic rocks are usually poor aquifers as they have less pore space
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Porosity can increase over time due to weathering and tectonic activity
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Hydraulic head refers to the potential energy of groundwater, determined by the elevation to which water will rise in a well
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Water flows from areas of high hydraulic head to low hydraulic head.
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Darcy's Law calculates the amount of groundwater flow through sand
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Groundwater flow models use hydrological maps to predict the effects of changing stressors like recharge rates, pumping rates, and river stages
Aquatic Ecosystems
- A community is an assemblage of interacting living organisms within a location
- Adjacent communities can interact, such as terrestrial predators on aquatic critters
- An ecosystem includes both biotic and abiotic components that interact
- The niche describes a species' position within an ecosystem, including its persistence conditions and ecological role
- Important ecological niche dimensions for aquatic organisms include temperature, dissolved oxygen, habitat structure, predation, and plant nutrients
- Biological diversity encompasses genetic diversity, species diversity, alpha diversity, beta diversity, gamma diversity and ecosystem diversity
- Ecological functioning refers to the processes by which biological and non-biological elements interact to generate change in an ecosystem
- Disrupting ecological functioning can affect a single organism and the entire ecosystem due to interconnectedness
- Lotic systems are flowing waters, characterized by variability at different levels: whole catchment, river reaches, segments, and patches/microhabitats
- Lentic systems are still or standing waters.
- Lakes have distinct zones: littoral, pelagic photic, profundal, and benthic
- Aquatic ecosystems typically have high biodiversity, including amphibians, mammals, birds, macrophytes, and algae.
- Organisms in aquatic ecosystems are grouped by trophic role: producers, consumers, detritivores, and parasites
- Autochthonous resources originate within the aquatic ecosystem
- Allochthonous resources originate from adjacent terrestrial ecosystems
- Primary producers use photosynthesis to create energy for the food web.
- Consumers are heterotrophic and link energy and biomass from primary producers or terrestrial inputs to the food web.
- Food webs are complex, making predictions about environmental change difficult.
- The number of species and biomass decreases with food web height due to energy transfer inefficiencies.
- Food webs vary in space and time, with terrestrial ecosystems feeding aquatic ecosystems
- Community respiration is the biological process of using organic matter in the presence of dissolved oxygen for metabolism, growth, and reproduction.
- Nutrient spiraling differs from nutrient cycling due to downstream water flow, measuring nutrient movement in the ecosystem.
- Nitrogen is essential for all organisms, and its availability depends on microorganisms.
- Phosphorus is essential for chemical processes, but its supply is limited.
- Stratification hinders nutrient cycling due to vertical mixing of water, influenced by factors like energy input, wind, and density differences.
- Estuaries and salt marshes are highly productive due to plentiful nutrients from rivers and tidal flow.
- Eutrophication is the overproduction of organic matter in a lake or river, potentially causing oxygen depletion.
- Hypoxic zones in shallow marine ecosystems are characterized by low oxygen levels, often caused by high nutrient concentrations.
- Ocean production is typically low due to a lack of nutrients, though temperature and climate factors also play a role.
- Invasive species can affect trophic interactions, alter the effects of competitors, and impact native ecosystems.
- Invasive species can act as ecosystem engineers, drastically altering the environment and reducing biodiversity.
Water and Health
- Pollution is a substance causing environmental degradation
- Pollution solutions used to focus on dilution, but the environment can no longer handle the amount of waste produced.
- New, non-biodegradable products pose further challenges to pollution management.
- Biodegradable wastes break down through microbial action.
- Non-biodegradable wastes remain unaltered, polluting the environment
- Point source pollution is from a single, identifiable location, like sewage outflows.
- Diffuse discharge is from an unidentifiable location, such as acid rain or fertilizer runoff.
- Pollutants can have direct toxic effects on aquatic organisms or indirect effects by altering the habitat.
- Ecological shifts can occur due to continuous pollution, leading to changes in species composition.
- Intermittent pollution causes the most damage to ecosystems.
- Sewage discharge can alter the physical environment, reduce oxygen concentrations, change species composition, and spread diseases.
- Oil spills can directly impact organisms through ingestion or contamination, and indirectly by smothering habitats or altering shoreline sensitivity.
- The Deepwater Horizon oil spill in 2010 caused severe damage to the Gulf of Mexico ecosystem, impacting marine life and coastal habitats.
- Nutrients can be limiting factors for plant and algae growth, leading to eutrophication.
- Accumulating toxic wastes, like heavy metals, PCBs, and radioactive discharges, can bioaccumulate and biomagnify in organisms.
- Pesticides, PCBs, and CHCs can cause fish kills, long-term subacute effects, and sterility in wildlife.
- Endocrine disruptors mimic and disrupt hormone-mediated processes, potentially affecting fertility and causing feminization in organisms.
- Inert solids physically impact the environment by clouding waterways.
- Microplastics and nanoplastics are a global contaminant, impacting aquatic organisms and human health.
- Mine wastes can cause high TSS, toxic metals, and ecosystem degradation.
- Acidification in freshwater ecosystems occurs when atmospheric acid deposition exceeds the buffering capacity of the water, impacting aquatic organisms.
- Marine acidification increases ocean acidity, harming calcifying organisms like corals and shellfish.
- There are four categories of infectious diseases related to water: waterborne, water-washed, water-based, and vector-based water-related.
- Water-related infections are a leading cause of death worldwide.
- Natural disasters impact water quality and quantity, increasing disease risks.
- Water pollution can be cleaned up through reduction, treatment, and biological cleaning.
- BPEO (Best Practicable Environmental Option) and BATNEEC (Best Available Technology Not Entailing Excessive Costs) are used to guide cost-effective pollution management strategies.
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