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marine ecotox > intro to marine ecotox > Flashcards

intro to marine ecotox Flashcards

1
Q

aquatic toxicology

A

the study of the effects of chemicals and other natural and anthropogenic materials (i.e. toxic agents) on aquatic organisms

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2
Q

ecotoxicology

A

a subset of aquatic toxicology that evaluates the changes in the communities of individual organisms in response to a toxic agent

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3
Q

toxicokinetics

A

the movement and transformation of pollutant compounds from the aquatic environment and into organisms.

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4
Q

endpoints (definition)

A

signals that indicate adverse impacts caused by exposure and include:

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5
Q

endpoints (examples)

A
  • Lethality - the number of organisms killed or survived after an exposure event
  • Reproductive success - in aquatic organisms this can be measured by egg production, hatchability, and recruitment—the number of juvenile organisms surviving to adulthood
  • Whole body or organ condition factors - these include physical measurements of length, weight, and health indices (e.g. motility, lethargy, behavior changes)
  • Mutagenesis or teratogenesis - molecular changes leading to tumors, birth defects, and cancer
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6
Q

bioaccumulation

A

the accumulation of environmental toxins within the body of an organism

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7
Q

PAH

A

polycyclic aromatic hydrocarbons -persistent type of contaminant associated with oil and gas exploration

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8
Q

biomedical toxicology

A

focuses on human health, using mammalian models as the basis for experimentation, testing, and data interpretation. The priority is to reduce the harmful effects of environmental pollutants on human populations.

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9
Q

ecotoxicology vs mammalian toxicology

A

ecotox :

  • protect communities of diverse species from toxic substances
  • can experiment directly on species of concern
  • organisms live in variable environmental conditions, are mostly poikilothermic. Toxicity may not be predictable
  • External exposure (dose) and duration from water, sediment can be known—actual absorbed does is often determined experimentally using metabolism and bioaccumulation and bioconcentration studies
  • less research, emphasis of toxic effects and threshold concentrations, regulatory purposes
  • test methods are new and usefulness uncertain

mammalian toxicology:

  • protect humans
  • uses animal models, cant feasibly experiment on humans
  • homeothermic organisms, toxicity predictable
  • doses of chemicals can be measured directly and accurately, administered through several routes
  • extensive research, focus on mechanisms of toxic action
  • test methods well developed, usefulness/limits understood
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10
Q

Phase of physical environment (4)

A
  • Air
  • Water
  • Soil and sediment
  • Biota (Tissue of living organisms)
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11
Q

Physical transport

A

the movement of chemical compounds without reaction or interaction with other environmental phases

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12
Q

reactivity

A

the chemical or biochemical reactions of chemical compounds with other environmental phases

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13
Q

Netric zone

A

nearshore regions

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14
Q

pelagic zone

A

deep ocean regions

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15
Q

abiotic components

A

nonliving elements that comprise the physical aquatic environment, including temperature, pH, salinity, dissolved gases, suspended particulates, and many more

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16
Q

Xenobiotics

A

any foreign substances or exogenous chemicals (e.g. from outside the organism) which the body does not recognize

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17
Q

duration

A

also referred to as an exposure event and can be acute or chronic in type. For example, intermittent chemical spills are classified as acute exposure events, where as continuous discharge of a waste stream into a water body is classified as a chronic exposure event.

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18
Q

resiliency properties

A

properties of an ecosystem enabling it to resist change that result from the presence of a pollutant. These properties include pH buffering capacity, dissolved organic matter (DOM) concentrations of the water column, tidal flushing events, and more

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19
Q

water

A
  • facilitates chemical reactions

- conduit for transport of nutrients and waste

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20
Q

water (specific heat)

A

water has highest specific heat of common fluids. Takes a lot of energy to alter water temperature. Buffering effect, keeps organisms in narrow range of temperature. Specific heat is LOWERED by addition of solutes.

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21
Q

water (density)

A

highest water density at 4 degrees C. Density decreases above and below this point. This phenomenon causes water to freeze from the surface downward. Cold water is more dense than warm, so it sinks, leads to vertical mixing in shallow water and thermal stratification in deep water.

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22
Q

viscosity

A

characterizes a liquids resistance to flow (high viscosity = high resistance). measured in poise/centipoise

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23
Q

viscosity of water

A

increases with decreasing temperature. viscosity caused by hydrogen bonds resulted in internal friction . affects the energy output of organisms via locomotion

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24
Q

Reynolds number

A

(Re) dimensionless value. Predicts laminar or turbulent flow. Ratio of momentum to viscosity.

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25
Q

Re formula

A

ReD = pVD/u = VD/v

V is flow velocity (velocity of the fluid with respect to the object)
D is characteristic linear dimension (related to the shape of the object)
ρ is fluid density
μ is dynamic viscosity (fluid)
ν is kinematic viscosity (the velocity of the fluid)

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26
Q

Laminar flow

A

Re < 2000

Rare, particles move in straight lines, layers of water move over each other at different velocities with no mixing

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27
Q

Turbulent flow

A

Re > 2000

high velocity fluid, particles move irregularly. Average motion is in one direction, common

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28
Q

surface tension

A

water has high surface tension due to hydrogen bonds in all directions but the surface-air interface. The surface has higher potential energy and is under tension.

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29
Q

surface tension relationship with other properties of water

A

ST decreases with increasing temperature
ST decreases with increasing conc. of organic substances in column
ST increases slightly in presence of dissolved salts

Substances that lower surface tension, such as organic matter, become positively sorbed to particulates. As such, concentrations of chemical compounds in the aqueous phase are affected by the interfacial tension between the substance (organic matter) and water.

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30
Q

turbidity

A

presence of suspended solids

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31
Q

conservative components of sea water

A

most abundant
non-reactive and have long residence times in the ocean water. They include: chlorine, sodium, calcium, potassium, magnesium, and sulfate.
together they make up 99% of dissolved solute, sodium and chlorine comprise 86% alone.
in estuarine and land locked seas elements may not be acting conservatively, especially with riverine input.
The ratio of conservative components to chloride concentrations are the same in all seawater.

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32
Q

nonconservative components of water

A

chemically or biologically active, vary from place to place in the ocean
O2, CO2, H2S, and more
potassium, phosphate
organic compounds like amino acids and humic substances
sand, clay, microorganisms
trace metals nickel, lithium, and iron
non conservative components comprise a very small percentage of total solute

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33
Q

salt

A

ocean salinity: 33-37%, average 35%
Venice System: marine (ocean water) is greater than 30 percent, estuaries range between 0.5 and 30 percent and freshwaters are those less than 0.5 percent.

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34
Q

oxygen

A

most oxygen in the water column comes from the atmosphere. Dissolution from atmosphere is primary means of reoxygenation after consumption of oxygen by organisms.
concentration of dissolved oxygen regulates organismal and metabolic processes (cellular respiration and decomp).

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35
Q

factors affecting atmospheric o2 dissolution rate

A

wave action - increases o2 conc. through aeration
partial pressure - greater diff. in pp between air and water increases dissolution of o2 based on Henry’s Law
photosynthetic algae - produces oxygen dissolved in column, not an efficient means of reoxygenation

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36
Q

solubility of oxygen in water

A

increase temp decreases solubility

increase salinity decrease solubility

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37
Q

hypoxia

A

low oxygen water, less than 2mg/L dissolved oxygen

38
Q

anoxia

A

complete depletion of dissolved oxygen

39
Q

carbon dioxide

A

along with oxygen most abundant gas in fresh/sea water
highly soluble in natural waters, solubility varies due to equilibrium with bicarbonate (HCO3-) and carbonate (CO3-2) ions

40
Q

co2 speciation

A

co2 speciation is pH dependent. Buffer action prevents shifts in acidity/alkalinity.
pH < 6, CO2 predominates
pH 6-10, HCO3- predominates (most natural waters)
pH>10, CO3-2 predominates

41
Q

co2 and biological processes

A

CO2 regulates plant growth and cellular respiration. CO2 is derived from bacterial decomposition of organic matter, a form of cellular respiration. some reactions between acids and carbonate compounds release CO2, and the atmosphere supplies some CO2.

42
Q

organic constituents

A

dissolved solids include hydrocarbons, carbohydrates, lipids, fatty acids, and amino and nucleic acids

43
Q

organic matter in the aqueous environment

A

an important source of electrons that drive biologically mediated redox reactions.
Heterotrophic organisms require organic compounds for carbo and chemical energy source for cell metabolic functions inc. respiration.

44
Q

what determines the distribution of organic compounds in the water column?

A

biological activity and the biogeochemical cycling of carbonaceous material

45
Q

autochthonous sources

A

carbon derived from primary production (photosynthesis) and other autotrophic processes
largest fraction of POC in algae-dominated systems and includes biomolecules of lipids, pigments, proteins, and polysaccharides. settle slowly in the water column and undergo microbial degradation. degradation continues after this fraction of organic matter reaches the sediments.

46
Q

allochthonous sources

A

plant and soil organic matter transported from the watershed into marine waters. These compounds are rich in plant structural material including lignins and cellulose. largely biologically recalcitrant and tier uptake and turnover in the water column happens slowly.

47
Q

POC

A

Particulate organic carbon

48
Q

primary productivity

A

plants assimilate energy by photosynthesis and produce biomass (glucose). transferred to heterotrophic consumers (primary and secondary)

49
Q

photosynthesis

A

6CO2 + 6H20 + light energy = C6H12O6 + 6O2

or

inorganic carbon + nutrients + light energy = biomass + heat

50
Q

GPP

A

gross primary production

total amount of energy fixed by plant matter.

51
Q

NPP

A

Net primary production
total amount of energy available for plant growth and reproduction after accounting for respiration

NPP = GPP - respiration

52
Q

particulate vs dissolved matter

A

particles retained by greater than .45 micrometer filter are solids or particulate matter and include sand, clay, microorganisms, and more
particles that pass through the .45 um filter are refereed to as dissolved matter and include colloidal compounds such as humic acid polymers and polysaccharides

53
Q

dissolved vs particulate organic matter

A

DOM vs POM

dissolved organic matter can adsorb to particles in the water column to from aggregates of POM.

54
Q

DOC

A

Dissolved organic carbon
chemically reactive fraction of the compound and provides the mass of organic carbon (OC) dissolved in water. measure of the organic molecules that make up the dissolved organic load in the water column.

55
Q

POC

A

Particulate organic carbon, analogous to suspended organic carbon and is comprised of plant and animal organic matter and silt and clay.

56
Q

TOC

A

total organic carbon in the aquatic system, sum of DOC, POC, and colloidal particles. Organic matter refers to the whole molecules and includes oxygen and hydrogen atoms. These concentrations are difficult to quantify so TOC is used instead.

57
Q

seawater DOC concentration

A

seawater has low DOC concentration (ranges from 1.0 mg/L in surface water to 0.5 mg/L in deep water system)
surface water has higher concentration due to photosynthetic activity of phytoplankton (also source of POC due to aggregation)

58
Q

seawater POC concentration

A

less than DOC concentration, range from 0.01 to 0.1 mg/L.

59
Q

coastal water DOC

A

coastal waters have higher concentrations of DOC due to increased rates of primary productivity, range from 1-3 mg/L. Organic matter is also introduced from riverine and terrestrial sources. DOC of larger rivers ranges from 2-10 mg/L. Increased concentrations of suspended solids (Total suspended solids (TSS)) strongly related to sediment loading and river discharge

60
Q

estuary DOC

A

concentration between river and marine level

61
Q

relationship between salinity and DOC

A

linear, inverse. Higher salinity, lower DOC

62
Q

humic substances

A

high molecular weight (500-5000 g/mol)
generated by microbial decomposition of organic matter
3 types: fulvic acid, humic acid, and humin (determined by solubility)
heterogonous mixtures of compounds, no single structural formula
natural chelating agents, affect the distribution and fate of aquatic pollutants

63
Q

fulvic acid

A

soluble in acid AND alkali environment
provides binding sites for metals
precipitates metal ion out of the solution
without fulvic acids, metal ions would partition into the sediment, form of phase transport.
represents most of the humic material in water

64
Q

humic acid

A

insoluble in acid, soluble in alkali environment
effectively exchange cation and organic substances with water, creating a nonpolar environment into which hydrophobic chemicals escape. also can reduce oxidized metal species, allowing the metal ion to be fixed to the humic matter
fixation makes metal unavailable for solubilization or uptake by living organisms (biounavailable)

65
Q

humic matter in seawater

A

low concentration (0.06 to 0.6 mg C/L

66
Q

properties of humic substances and their functions in soil

A

Properties and Function of Humic Material in Soils and Sediments

Properties

Comments

Function in Soil

Color

Dark color of soils is caused by organic matter

Facilitates soil warming

Water retention

Organic matter can hold up to 20 times its weight in water

Improves moisture retention of soils

Combination with clay minerals

Joins soil particles into structural aggregates

Permits gas exchange; stabilizes soil structure; increase permeability

Chelation

Forms stable complexes with metal ions

Buffers the available of metals to vegetation

Solubility in water

Insolubility of organic matter results from its association with clay; source of dissolved organic matter

Exports recalcitrant dissolved organic matter to adjacent aquatic systems

pH

Organic matter buffers soil pH in slightly acidic, neutral, and alkaline soils

Helps maintain a relatively constant pH

Cation exchange

Total acidities of humus fractions range from 3, 000 to 14,000 mmol/kg

Increase the cation exchange capacity (CEC) of the soil; 20 to 70 percent of the CEC capacity is due to organic matter

Mineralization

Decomposition of organic matter produces gases and nutrients

Energy source for microbes; source of nutrients for plan growth; source of greenhouse gases

Combination with organic molecules

Affects bioavailability, persistence and biodegradability of toxic organic compounds

Decreases bioavailability of toxic organic compounds to biota

67
Q

nutrient remineralization

A

organic matter is consumed by heterotrophs and passed through food chain to drive biologically mediated reactions like cell respiration. Biochemical processes convert nitrogen, phosphorous, and carbon to soluble forms and increase nutrient recycling rates and concentrations.

68
Q

solubility of xenobiotics

A

POM in the water column can bind to xenobiotics, can remain suspended in the water column, or be deposited on the sediment surface. (particle size, conc. , polarity, and spatial distribution influence the adsorption of foreign chemicals onto suspended particles). xenobiotics bound to particles in the aquatic environment reduce the bioavailability of potentially toxic chemical compounds to living organisms. soluble chem are more available for uptake/ more toxic to organisms

69
Q

active layer of sediment-water interface

A

top 10cm of aquatic sediment

70
Q

suspended aquatic sediments

A

0,1-200 micrometers in diameter, include fine sand, silt, and clays. Typically heterogenous mixtures and can include organic biota. inorganic constituents include silica, alumina, and iron- manganese oxides. can be pure mineral to pure organic

71
Q

clay particles

A

substantial adsorptive capacity due to large surface area to volume ratio and surface charge (-)

72
Q

Exchangeable cation status

A

(ECS) ability of clay particles to exchange cations with the aqueous phase

73
Q

cation exchange capacity

A

is the amount of exchangeable cations held in the soil. It is a measure of the capacity of a sediment (solid phase) to sorb cations and it varies based on both pH and salinity.

74
Q

freshwater sediment CEC

A

20-30 milliequivalents/100g

75
Q

freshwater sediment ECS

A

range from less than 1 to 20 milliequivalents/100g

76
Q

pore/interstitial water

A

fluid in open spaces between sediment particles.

77
Q

adsorption

A

chemical compounds are taken up by surface interaction with solids

78
Q

absorption

A

chemical compounds are incorporated into the body of the material (matrix) to which it is bound

79
Q

partitioning of nonionic nonpolar molecules

A

partitioned onto the organic carbon fraction contained in marine sediments

80
Q

partitioning of moderately polar organic molecules

A

sorbed through hydrogen bonding, cation exchange, and nonpolar partitioning interactions between the compound and the sediment surface.

81
Q

advection

A

movement of fluid masses carrying pollutants

82
Q

diffusion

A

the natural tendency of molecules to move from regions of higher concentration to regions of lower concentration. referred to as Fickian transport or molecular diffusion. approximated by turbulent mixing (eddies, stream flow)

83
Q

convection

A

the vertical movement or advection of water

84
Q

bioturbation

A

the restructuring of sediment deposits by benthic organisms. alters the physical processes that mediate chemical transport
(burrowing, swimming)
increases mobility, solubility, bioavailability of previously sequestered chemical compounds.

85
Q

bioturbation marine vs freshwater

A

effects of bioturbation are greater in marine ecosystem due to larger organisms that disturb the sediment layer (crustaceans, polychaetes, mollusks)

86
Q

oxic zone

A

upper 10cm of marine sediments
relatively homogeneous chemical distribution
oxidizing chemical reactions predominate

87
Q

anoxic sediments

A

well defined concentration gradients for particular chemical compounds (reducing reactions predominate in anoxic sediment layers)

88
Q

ingestion

A

plays largest role in bioaccumulation of environmental contaminants in aquatic organisms

89
Q

what abiotic processes cause movement of contaminant out of sediment into porewater or water column

A

1 elevation of salinity, changes speciation of compounds
2 changes in oxidation/reduction state of sediment layer. changes speciation of chemical compounds
3 reductions in sediment pH, releases mobile, free organic compounds and metals into the aqueous phase
4 presence of complexing agents, releases organically bounds organic compounds and metals into the aqueous phase

90
Q

reactions in natural aquatic systems:

A 
Acid-base reactions
Complexations
Dissolution-precipitation reactions
Oxidation-reduction reactions
Sorption-desorption mechanisms
Hydrolysis reactions
Photolysis reactions

marine ecotox (1 decks)

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