Lecture 7 - Chemical pollution, methods, risk assessment Flashcards
Environmental vs. Eco-toxicology
Environmental toxicology: The study of the environmental factors that can influence the exposure of organisms to potentially toxic chemicals.
- How chemicals interact with the environment (ex. how they cycle and where they accumulate)
Ecotoxicology: The study of the directly poisonous effects of chemicals, in addition to their indirect ecological effects.
- Impacts of chemicals on the environment and its inhabitants (ex. how they alter species composition and how accumulation influences ecosystem processes).
Acute vs. chronic toxicity
Acute toxicity: Short-term exposure to a chemical at a high enough concentration to cause biochemical or anatomical damages, or even death.
Chronic toxicity: Long-term exposure to low or moderate concentrations of a chemical. Over time, chronic exposure may cause biochemical or anatomical damage, or even death.
How to measure toxicity: dose response curves
LD50: “lethal dose 50%”, the amount of a compound required to kill half of a population of experimental animals.
- usually measured in amount of chemical per unit bw
Dose response curves
- Therapeutic effect: ED50
- Toxic effect: TD50
- Lethal effect: LD50
Types of toxins
- Carcinogens
- Mutagens
- Teratogens
- Allergens
- Neurotoxins
- Endocrine disruptors
Examples of water pollution
Ex. Surface Water Pollution
- road run off from the rain
- farm run off
- human waste
- thermopollution
Decrease water pollution by:
- reduce agricultural runoff
- improve wastewater management systems
- stricter cooling regulations for power plants
Persistent organic pollutants: impacts and 3 main categories
Organic compounds that are resistant to degradation/decomposition via biological, chemical, and photolytic processes.
1. Pesticides
2. Industrial chemicals
3. By-products
Bioaccumulation vs. biomagnification: definition and impact on food webs
Bioaccumulation:
- accumulation within an individual over time
- starts at lower levels of a food chain
Biomagnification:
- concentration increases throughout trophic levels
- pollutants in the tissues of organisms reach higher concentrations
- ex, Mercury in an aquatic ecosystem
Environmental Risk Assessment: definition and step-by-step quantitative and qualitative evaluation
Quantitative:
Evaluation of the risks associated with some sort of hazard in the environment.
1. The likelihood of encountering the hazard
2. The likely intensity of the hazard
3. The biological damage that is likely to result from the predicted exposure
Short vs. long term methods of tracking environmental changes
Short-term: Monitoring
- ex. quantifying the amount of algae in a river upstream and downstream from a pipe discharging water from a municipal waste treatment facility
Long-term: Paleoecology
- uniformitarianism: the present is the key to the past
- analogy: application of modern organismic features to ancient organisms
- inform conservation and restoration practices
- guide to future decision making about the environment
What is Paleoecology?
Long-term method of tracking environmental changes
- uniformitarianism: the present is the key to the past
- analogy: application of modern organismic features to ancient organisms
- inform conservation and restoration practices
- guide to future decision making about the environment
What are the steps of the paleolimnological approach?
- Select study lake
- Select coring site and retrieve sediment core
- Section and date sediment core
- 1 varve = 1 yr sediment deposition
- light (summer) layer + dark (winter) layer - Sub-sample sediments and isolate indicator of interest
- Collect indicator data
- aquatic systems: diatoms, chrysophytes, chironomids
- land: pollen, mineral particles, insect remains
- atmosphere: carbon particles, fly ash, metals and pollutants - Analyze data
Methods of detecting the environmental impacts of pollution
- Mesocosm
- corrals (mesocosms) put into natural enviro, isolate the area, measure that area
- can apply dif test groups to the corals
- when we isolate these mesocosms over a period of time they will no longer reflect what is happening in the greater enviro - Whole-ecosystem approach
- Experimental Lakes Area (ELA)
- entire lake is the site of the experiment
- Lake 226: nitrogen, carbon on one side; nitrogen, carbon and phosphorus on the other
- Hubbard Brook Experimental Forest: forest equivalent of the ELA
Synergistic Effects
Interactive impacts of toxins that are more than, or different from, the simple sum of their constituent effects
Global Distillation Effect
aka the Grasshopper effect
- at low latitudes evaporation of pollutants exceeds deposition
- pollutants are transported by atmosphere and ocean curents
- at high latitudes, deposition of pollutants exceeds evaporation
- pollutants enter the polar food web and bioaccumulate
