Bio 346 - Freshwater Eco. (Chpt 28) --> Contaminants Flashcards
What are 4 common contaminants?
- H+
- SOx
- NOx
- Al
What are the principle environmental issues in limnology?
Toxic chemicals
What 2 practices can better reserve eutrophication?
- Better waste water treatment
2. Better agriculture practices
Many contaminants come from where?
Industrial processes
- Some are produced in nature during degradation
What are 3 chemicals that have great concern?
- Fungicides
- Insecticides
- Herbicides
- Which are all used in the production of human food
Negative effects of chemicals on…
- Specie diversity
- Community structure
- Human health
What does POPs stand for?
Persistent organic pollutants
What can POPs do?
They can alter of block the hormone system of individual invertebrate and can chain immune system and possibly produce carcinogenic effects
What are the chemicals of greatest concern worldwide?
Highly chlorinated organic molecules known as organochlorines (OCs)
POP has what kind of solubility in water and accumulation in fat?
- Low solubility
- High accumulation
What does PCH stand for?
Polychlorinated hydrocarbons
What does PCB stand for?
Polychlorinated biphenyls
What are PCHs examples of?
PCB
What are PCB?
They are organic chlorine compounds that vary based on the ratio of chlorine to biphenyl and the production temp
Acute toxicity
Quick death
Sublethal/chronic toxicity
Impairment of growth, breeding success
Carcinogenicity toxicity
Impairment, death
Mutagenicity and teratogenicity toxicity
Effects on future generations
Genotoxicity
Possible effects on future generations
- Effects genes/ DNA
What happens to the [ ] of bioaccumulation over time?
It increases
What is the 2nd attribute of many toxic substances?
Resistance to degradation
How are toxins that have a vapour phase transported?
Through the atmosphere
How do hydrophobic contaminants that contain high bioaccumulation get absorbed? (3 things)
Through the…
- Gills
- Guts
- External surfaces of living organisms
How do hydrophilic contaminants that contain high bioaccumulation get absorbed?
Usually reminded dissolved in the water
How are PCBs released?
- Leakage
- Spills
- Escape from waste storage sites
What are 4 examples of toxic trace metals?
- As
- Cd
- Hg
- Pb
What is an important contaminant for wetlands?
Mercury
What is one of the worst chemicals humans every synthesized?
PCBs
Why are lead levels increasing?
It is due to human activity
- Industrial revolution
Lake Superior is now acting more like a ____ rather than a ____
- source
- sink
Hydrophilic
Those that dissolve readily in water (water-loving) = high solubility
Hydrophobic
Those that don’t readily dissolve in water (water fearing) = low solubility
Where does mercury accumulate?
In tissues
- not fat
What causes dips in the graph?
High sediment loading followed by dilution
The extent to which a contaminant is bioavailable upon its arrival in aquatic systems is mainly determined by what?
By its solubility in water
Hydrophilic contaminants are more likely and less likely to do what compared to hydrophobic?
- Contaminants are more available for direct nutrient uptake
- Less likely to be removed by sedimentation or filter-feeding organisms
What does electronegativity represent?
The power of an atom to attract electrons to itself in a covalent bond
The greater the electronegativity is the ____ the solubility is
Lower
What does QSAR stand for?
Quantitative Structure Activity Relationships
What is QSAR?
It is a model that first summarizes a supposed relationship between chemical structures and biological activities in a data-set of chemicals
Octanol
Describes the equilibrium [ ] between water and a solvent
What does Kow indicate? (4 things)
- The uptake potential by organisms
- The potential for bioaccumulation from the water
- The biomagnification potential in food webs
- The residence time of persistent organic pollutants in the enviro
More electronegativity has a ___ octanol solubility
High
Least soluble
Highest octanol
High Kow
More neutrophilic the more they accumulate in fat
- Hydrophobic
What does Kow serve as?
A surrogate for the solubility of toxic compounds in water
Low Kow
Hydrophilic
Biomagnification
The cumulative increase observed in the [ ] of persistent contaminants at successively high levels in food webs
- Obtained from the predator:prey [ ] ratio
Bioaccumulation Factor (BAF)
Represents the organism [ ] : enviro [ ] ratio
What class is most effected by bioaccumulation and least affected?
Most = Class 3 (long food chain) Least = Class 1 (short food chain)
What happens to PCB levels in the body as trophic levels increase?
They increase
- Cause harm/damage
