Pollution Flashcards
(10 cards)
Define eutrophication.
Eutrophication is a process that occurs when a body of water becomes enriched with nutrients, which causes excessive plant and algae growth.
What are the causes of eutrophication?
Nutrient Leaching: Rainfall dissolves water-soluble nutrients from fertilizers, washing them into groundwater, rivers, and lakes.
Runoff: Nutrient-rich water flows into aquatic systems, overloading them with nutrients.
Describe the stages of eutrophication.
1. Nutrient Enrichment Fuels Algal Blooms: Excess nutrients stimulate the rapid growth of algae and aquatic plants.
2. Algal Blooms Block Sunlight: Dense algal blooms form, covering the water’s surface and preventing submerged plants from photosynthesizing.
3. Decomposition Depletes Oxygen: As algae die and decompose, bacteria consume oxygen, raising the biochemical oxygen demand (BOD).
4. Hypoxia and Aquatic Life Decline: Oxygen levels drop, creating hypoxic (low oxygen) or anoxic (no oxygen) conditions. Fish and other aerobic organisms die or migrate.
Explain the eutrophication of aquatic and marine ecosystems due to leaching.
A rapid growth in algal populations will occur (algal blooms) as a result of the increased availability of nutrients
As the algae die, there will be a subsequent spike in the numbers of saprotrophic microbes (decomposers)
The high rate of decomposition will result in an increased biochemical oxygen demand (BOD) by saprotrophic bacteria
The saprotrophs will consume available quantities of dissolved oxygen, leading to deoxygenation of the water supply
Eutrophication will also increase the turbidity of the water, which will reduce oxygen production by photosynthetic seaweeds
This will stress the survival of marine organisms, potentially leading to a reduction in biodiversity within the ecosystem
Define biomagnification.
Biomagnification is the process in which chemical substances become more concentrated at each trophic level.
Outline the process of biomagnification.
- Pollutant enters the environment.
- Pollutant is absorbed by producers.
- Bioaccumulation in consumers - herbivores ingest the producers, storing the toxins in their tissues
- Magnification at higher trophic levels - predators consume multiple prey, concentrating the toxins further
Discuss the cause and effect of mercury biomagnification in an ecosystem.
Mercury is a heavy metal that can be released into the environment through activities such as coal-fired power generation and gold mining
The mercury is then converted by microorganisms into highly toxic methyl-mercury, which accumulates in the bodies of consumers (such as fish)
At each subsequent trophic level, the concentrations of methyl-mercury within the tissues increases due to increased food intake
This can lead to mercury poisoning in humans who eat the larger predatory fish
Discuss the cause and effect of DDT biomagnification in an ecosystem.
DDT is a chemical pesticide that is sprayed on crops and subsequently washed into waterways at low concentrations
As it is fat soluble, it is retained within the tissues of aquatic algae instead of being excreted
At each subsequent trophic level the concentration of DDT stored in the body increases due to increased food intake
Very high levels of DDT were discovered in birds that preyed on fish, and was found to interfere with eggshell formation
Birds exposed to high levels of DDT were found to produce thinner shells, which decreased survival rates of fledglings
The use of DDT is now largely restricted in most countries
Explain how macroplastics harm marince life.
Entanglement: Marine animals like sea turtles and seals get trapped in fishing nets, leading to injury or death.
Ingestion: Animals mistake plastic for food.
Describe the effects of plastic pollution on marine life.
Loss of Biodiversity:
Species ingesting or becoming entangled in plastic face population declines.
Reduced biodiversity impacts ecosystem stability.
Disruption of Food Webs:
Affected key species alter predator-prey dynamics.
This destabilizes the entire food web.
Chemical Pollution:
Plastics release harmful toxins like carbon compounds.
Toxins bioaccumulate and biomagnify, impacting organisms across trophic levels.
