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ENVS 4113 > Module 3 > Flashcards

Module 3 Flashcards

ENVS 4113 Midterm

1
Q

How do Pesticides Enter Drinking Water Sources?

A
  • Dissolved in agricultural field runoff water
  • Sorbed to soil particles in eroded soil
  • Leaching below agricultural field into groundwater
  • Drift from pesticide application
    –aerial
    –ground
    –other methods (i.e., orchard airblast, chemigation)
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2
Q

What is the primary factor that affects pesticide movement?

A

Water, but there’s also wind that can play a role.

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3
Q

What are two major components in surface water exposure modeling?

A

Hydrology and Sediment Transport

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4
Q

How can models be used to estimate exposure and explain the bigger picture?

A

Can be used to interpret field studies, extrapolate field studies to other environments, soils, weather, or crops, can evaluate sources of uncertainty, and are less expensive then field or lab studies.

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5
Q

True or False? Pesticide residues go where the water goes.

A

True

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6
Q

What is forced convection?

A

Involves the transport of fluid by atmospheric convection currents which can be set up by local heating effects such as solar radiation (heating and rising) or contact with cold surface masses (cooling and sinking).

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7
Q

What is convection?

A

The process by which heat is transferred by movement of a heated fluid such as air or water.

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8
Q

What is convection currents?

A

Primarily move vertically and account for many atmospheric phenomena, such as clouds and thunderstorms.

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9
Q

What is advection?

A

Is the transport of a substance or quantity by bulk motion.

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10
Q

Usually what is the form when a substance is advected?

A

Fluid form

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11
Q

True / False. An example of advection is the transport of pollutants or silt in a river by bulk water flow downstream

A

True

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12
Q

True / False. Another commonly advected quantity is energy or enthalpy.

A

True

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13
Q

During advection, the fluid in motion can be described mathematically as a __________? And the transported material is described as a ________ showing its distribution over space.

A

Vector Field & Scalar Field

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14
Q

Advection requires _________ in the fluid.

A

Currents

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15
Q

__________ is the combination of advective transport and diffusive transport.

A

Convection

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16
Q

In meteorology and physical oceanography, _______ often refers to the transport of some property of the atmosphere or ocean, such as heat, humidity (i.e., moisture), or salinity.

A

Advection

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16
Q

Dispersion

A

The process where matter flows from a high concentration to a low concentration.

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17
Q

Dispersion is discussed in what 3 things?

A

Optics, Sound Waves, and Water Waves

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18
Q

The process of ________ occurs when a high concentration of diffused matter is present.

A

Dispersion

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19
Q

What process causes particles to move in random directions and spread out in a medium and once the spreading out has finished, the system is considered to be in ___________.

A

Dispersion, Equilibrium

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20
Q

What is fusion?

A

The process where particles, molecules, or atoms combine to form larger units.

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21
Q

What is the reverse of fusion?

A

Diffusion

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22
Q

In ______, particles or molecules are separated from the original unit.

A

Diffusion

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23
Q

_____is required to break bonds regarding diffusion; therefore, the process is always _______.

A

Energy, Endothermic (The higher the temp the higher amount of diffusion.

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23
Q

True / False. The diffusion process does not always require breaking of bonds.

A

False - it always requires breaking of bonds.

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24
Q

The water and Ice example is related to what transformation process?

A

Diffusion

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25
Q

_______ describes physical phenomena where particles, energy, or other physical quantities are transferred inside a physical system due to two processes: _____ & _______

A

1) Convection-diffusion equation
2) Diffusion & Convection

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26
Q

In the convection-diffusion equation, c is considered what?

A

The variable of interest (Example: concentration of salt in a river)

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27
Q

In the convection-diffusion equation, D is considered what?

A

Diffusion coefficient

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28
Q

In the convection-diffusion equation, v is considered what?

A

Velocity Field

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29
Q

True / False. In the convection-diffusion equation, the equation means that the change in concentration over time is equal to the diffusion minus convection.

A

True

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30
Q

What is referred to as the predicted pesticide concentration in surface water?

A

Estimated Environmental Concentrations (EECs)

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31
Q

The _______ can be derived in a straightforward way from the _______, which states that the rate of change for a scalar quantity in a differential control volume is given by flow and diffusion into and out of that part of the system along with any generation or consumption inside the control volume

A

1) convection-diffusion equation
2) continuity equation

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32
Q

For Drinking Water assessments, the EECs are adjusted for the percent of the watershed receiving pesticide application. The adjusted EECs are called?

A

Estimated Drinking Water Concentrations (EDWCs)

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33
Q

The ________ or ________ states that for any system closed to all transfers of matter and energy, the mass of the system must remain constant over time because a system’s mass cannot change. Thus, a quantity can neither be added nor be removed. Hence, the quantity of mass is conserved over time.

A

Law of conservation mass
Principle of mass conservation

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34
Q

True / False. Matter can neither be created or destroyed, but it can be rearranged or change form.

A

True - Law of conservation mass

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35
Q

What is mass balance in modeling?

A

The total mass can not increase or decrease and must be accounted for in the output of the model. It can be rearranged.

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36
Q

What are the three processes that affect the fate of pesticides in the environment?

A

Transport, Transfer, Transformation

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37
Q

What does the term transformation mean in terms of pesticide movement?

A

Refers to biological and chemical processes that change the structure of a pesticide or completely degrade it

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38
Q

What does the term transfer mean in terms of pesticide movement?

A

Refers to the way in which a pesticide is distributed between solids and liquids (e.g., between soil and soil water) or between solids and gases (as between soil and the air it contains)

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39
Q

What does the term transport mean in terms of pesticide movement?

A

Movement from one environmental compartment to another, such as the leaching of pesticides through soil to groundwater, volatilization into the air, or runoff to surface water

40
Q

What are 3 examples of pesticide transport process?

A

Leeching through soil to groundwater, runoff to surface water, volatilization into the air (evaporate).

41
Q

What transport process degrades or changes the structure of a pesticide?

A

Transformation

42
Q

What are the 3 principle processes when understanding the environmental fate parameters?

A

Adsorption / Desorption to soil particles (Sorbed)
Degradation
Volatility

43
Q

________ is the average weight of a molecule of an element or compound.

A

Molecular Weight

44
Q

What is the sum of the atomic weights of all the atoms in a molecule.

A

Molecular Weight

45
Q

Define Solubility

A

The maximum quantity of a substance (i.e., solute) that may be dissolved in a solvent.

46
Q

1) When the maximum amount of solute is dissolved in a solvent at equilibrium, this leads to a ________. 2) What can be added to cause additional solution to be dissolved? 3) What does #2 produce?

A

Saturated Solution
Heat
Supersaturated Solution

47
Q

________ is a process that occurs when a gas or liquid solute accumulates on the surface of a solid or a liquid

A

Adsorption

48
Q

________ is a process in which a substance diffuses into a liquid or solid to form a solution.

A

Absorption

49
Q

1) What term encompasses both adsorption and absorption and 2) what is the reverse process?

A

Sorption
Desorption

50
Q

______ is a transfer process in which pesticides are dispersed between solid matter and water.

A

Sorption

51
Q

What is one environmental sink (retention or storage site) for many pesticides?

A

Organic Matter

52
Q

For pesticides, the pesticide residues _____ and _____ to ______ on the surface of soil particles.

A

adsorb & desorb
organic matter

53
Q

Pesticides that are _______ tend to remain at the surface of soil organic matter.

A

water soluble

54
Q

Pesticides that are ______ tend to penetrate to the hydrophobic interior

A

Insoluble

55
Q

The amount of pesticide sorbed is largely a function of the total amount of _____ (sorption regions) in the soil and the pesticide’s _______.

A

organic matter
water solubility

56
Q

Organic Matter is also known as what?

A

Humus

57
Q

What is DOC?

A

Dissolved Organic Carbon

58
Q

What is POC?

A

Particulate Organic Carbon

59
Q

What is formula for % Organic Carbon?

A

% Organic Carbon = % Organic Matter / 1.72

60
Q

The ________ can be used to estimate the adsorbed fraction for any chemical.

A

Soil/water equilibrium partition coefficient (Kd)

61
Q

The __________ is preferred for pesticides for which there is a strong positive correlation between the organic carbon and rate of adsorption.

A

Organic carbon normalized soil/water equilibrium partition coefficient (Koc)

62
Q

______ is basically is an indicator of whether a pesticide “prefers” to remain dissolved in soil pore water or sorb to organic carbon on the soil particles in a soil profile

A

Koc

63
Q

What is the First Order Degradation Equation?

A

ln(2.0)/t1/2 = k

64
Q

What is Photolysis in terms of pesticides?

A

Pesticides absorb energy from sunlight or other energy and degrade.

65
Q

What is an example of transformation process in terms of pesticides?

A

Microbial Degradation

66
Q

What is Microbial Degradation in terms of pesticides?

A

When bacteria or fungi partially or fully breakdown (metabolize) a pesticide.

67
Q

What are 2 types of microbial degradation?

A

Aerobic metabolism
Anaerobic metabolism

68
Q

Aerobic Metabolism Degradation is transformed into what?

A

Co2 and water

69
Q

Aqueous aerobic metabolism half-life is used to simulate pesticide degradation in the ______.

A

water column of water body

70
Q

Aerobic soil metabolism half-life is used to simulate the degradation of pesticides in the _____.

A

Field

71
Q

Anaerobic metabolism half-life is used to simulate pesticide degradation in the _______.

A

benthic sediment of a water body

72
Q

__________ are a simplification in a mathematical model of a physical system where variables that are spatially distributed fields are represented as single scalars instead.

A

Lumped Parameters

72
Q

What is this an example of? An electrical network, graphically represented by a circuit diagram in which voltages are assigned to the vertices and currents to the edges of the diagram.

A

Lumped Parameter

73
Q

Aerobic and anaerobic metabolism half-lives are examples of?

A

Lumped Parameters

74
Q

True / False? The metabolism studies generate “lumped” half-life estimates for the water and soil.

A

True

75
Q

What is hydrolysis in terms of a pesticide?

A

A process by which a pesticide reacts with a water molecule.

76
Q

The extent of pesticide breakdown is dependent on what?

A

pH

77
Q

Environmental factors that tend to increase volatilization include:

A

high temperature
low relative humidity
air movement

78
Q

What is volatilization in terms of a pesticide?

A

A process whereby a solid or liquid evaporates into the atmosphere as a gas

79
Q

A pesticide that is tightly sorbed to soil will have a ______ solution concentration and be _____ likely to volatilize.

A

Lower
Less

80
Q

_______ and ________ are typically used to estimate volatility in the models.

A

Vapor Pressure
Henry’s Law of Constant

81
Q

The solubility of a gas in a liquid is proportional to the pressure of that gas above the liquid is referred to as what?

A

Henry’s Law Constant

82
Q

Toxicologically significant metabolites are metabolites that comprise >= ____ of the parent compound.

A

10%

83
Q

Generally, toxicologically significant metabolites are simulated as _______ chemicals.

A

Independent

84
Q

____ or ______ processes transform one compound to another through chemical or biological reactions in different environmental compartments. ​

A

Degradation or transformation

84
Q

______ usually breaks down substances by such processes as hydrolysis or photolysis, but may also result in larger molecules by such processes as biosynthesis or polymerization.

A

Degradation

85
Q

A kinetic parameter describing an aspect of the rate at which a substance dissipates from the environment or an environmental compartment. ​

A

Degradation Rate

86
Q

True or False? Rate constants will only depend on the temperature or pH.

A

True

87
Q

The time taken for 50% degradation/dissipation of a test substance described by single first-order kinetics and following the concept of exponential decay, where the rate constant is independent of concentration and time. ​

A

Half-life

87
Q

Time required for a concentration or mass to decline by 50% or 90%, respectively.​

A

DT50 and DT90

88
Q

True / False. DT50 and DT90 do differentiate between transfer processes and degradation processes

A

False - they do not

89
Q

The EPA regulatory guidelines use 3 empirical models to estimate degradation half-lives:​

A

(1) Single First-Order Rate Model (SFO)​

(2) Nth Order Rate Model or also called​ Indeterminate Order Rate Equation Model (IORE)​

(3) Double First Order in Parallel (DFOP)​

89
Q

An equation or set of equations used to describe the decrease of substances from the environment or an environmental compartment by various dissipation/degradation processes.​

A

Kinetics models

90
Q

There are two software systems which use this kinetics guidance along with non-linear regression to estimate regulatory half-life estimates from laboratory and field data.​ What are they?

A

PESTDF from EPA & CAKE from Syngenta

91
Q

What does FOCUS stand for?

A

Forum for Coordination of pesticide fate models and their use

92
Q

The standard abiotic studies (hydrolysis and photolysis) more commonly follow ____ and derivation of appropriate rate constants is straightforward.

A

First Order Patterns

93
Q

If the SSFO value is less than the Sc value, use the ____ model.

A

SFO

94
Q

The _____ model consists of the sum of two first-order terms.

A

DFOP

94
Q

FOMC

A

First-Order Multi-Compartmental Model

ENVS 4113 (6 decks)

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