Module 3

Question 1

How do Pesticides Enter Drinking Water Sources?

Answer 1

• 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)

Question 2

What is the primary factor that affects pesticide movement?

Answer 2

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

Question 3

What are two major components in surface water exposure modeling?

Answer 3

Hydrology and Sediment Transport

Question 4

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

Answer 4

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.

Question 5

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

Answer 5

True

Question 6

What is forced convection?

Answer 6

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).

Question 7

What is convection?

Answer 7

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

Question 8

What is convection currents?

Answer 8

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

Question 9

What is advection?

Answer 9

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

Question 10

Usually what is the form when a substance is advected?

Answer 10

Fluid form

Question 11

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

Answer 11

True

Question 12

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

Answer 12

True

Question 13

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.

Answer 13

Vector Field & Scalar Field

Question 14

Advection requires _________ in the fluid.

Answer 14

Currents

Question 15

__________ is the combination of advective transport and diffusive transport.

Answer 15

Convection

Question 16

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.

Answer 16

Advection

Question 16

Dispersion

Answer 16

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

Question 17

Dispersion is discussed in what 3 things?

Answer 17

Optics, Sound Waves, and Water Waves

Question 18

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

Answer 18

Dispersion

Question 19

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 ___________.

Answer 19

Dispersion, Equilibrium

Question 20

What is fusion?

Answer 20

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

Question 21

What is the reverse of fusion?

Answer 21

Diffusion

Question 22

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

Answer 22

Diffusion

Question 23

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

Answer 23

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

Question 23

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

Answer 23

False - it always requires breaking of bonds.

Question 24

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

Answer 24

Diffusion

Question 25

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

Answer 25

1) Convection-diffusion equation 2) Diffusion & Convection

Question 26

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

Answer 26

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

Question 27

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

Answer 27

Diffusion coefficient

Question 28

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

Answer 28

Velocity Field

Question 29

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

Answer 29

True

Question 30

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

Answer 30

Estimated Environmental Concentrations (EECs)

Question 31

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

Answer 31

1) convection-diffusion equation 2) continuity equation

Question 32

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

Answer 32

Estimated Drinking Water Concentrations (EDWCs)

Question 33

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.

Answer 33

Law of conservation mass Principle of mass conservation

Question 34

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

Answer 34

True - Law of conservation mass

Question 35

What is mass balance in modeling?

Answer 35

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

Question 36

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

Answer 36

Transport, Transfer, Transformation

Question 37

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

Answer 37

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

Question 38

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

Answer 38

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)

Question 39

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

Answer 39

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

Question 40

What are 3 examples of pesticide transport process?

Answer 40

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

Question 41

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

Answer 41

Transformation

Question 42

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

Answer 42

Adsorption / Desorption to soil particles (Sorbed) Degradation Volatility

Question 43

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

Answer 43

Molecular Weight

Question 44

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

Answer 44

Molecular Weight

Question 45

Define Solubility

Answer 45

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

Question 46

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?

Answer 46

Saturated Solution Heat Supersaturated Solution

Question 47

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

Answer 47

Adsorption

Question 48

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

Answer 48

Absorption

Question 49

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

Answer 49

Sorption Desorption

Question 50

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

Answer 50

Sorption

Question 51

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

Answer 51

Organic Matter

Question 52

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

Answer 52

adsorb & desorb organic matter

Question 53

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

Answer 53

water soluble

Question 54

Pesticides that are ______ tend to penetrate to the hydrophobic interior

Answer 54

Insoluble

Question 55

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

Answer 55

organic matter water solubility

Question 56

Organic Matter is also known as what?

Answer 56

Humus

Question 57

What is DOC?

Answer 57

Dissolved Organic Carbon

Question 58

What is POC?

Answer 58

Particulate Organic Carbon

Question 59

What is formula for % Organic Carbon?

Answer 59

% Organic Carbon = % Organic Matter / 1.72

Question 60

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

Answer 60

Soil/water equilibrium partition coefficient (Kd)

Question 61

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

Answer 61

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

Question 62

______ 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

Answer 62

Koc

Question 63

What is the First Order Degradation Equation?

Answer 63

ln(2.0)/t1/2 = k

Question 64

What is Photolysis in terms of pesticides?

Answer 64

Pesticides absorb energy from sunlight or other energy and degrade.

Question 65

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

Answer 65

Microbial Degradation

Question 66

What is Microbial Degradation in terms of pesticides?

Answer 66

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

Question 67

What are 2 types of microbial degradation?

Answer 67

Aerobic metabolism Anaerobic metabolism

Question 68

Aerobic Metabolism Degradation is transformed into what?

Answer 68

Co2 and water

Question 69

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

Answer 69

water column of water body

Question 70

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

Answer 70

Field

Question 71

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

Answer 71

benthic sediment of a water body

Question 72

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

Answer 72

Lumped Parameters

Question 72

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.

Answer 72

Lumped Parameter

Question 73

Aerobic and anaerobic metabolism half-lives are examples of?

Answer 73

Lumped Parameters

Question 74

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

Answer 74

True

Question 75

What is hydrolysis in terms of a pesticide?

Answer 75

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

Question 76

The extent of pesticide breakdown is dependent on what?

Answer 76

pH

Question 77

Environmental factors that tend to increase volatilization include:

Answer 77

high temperature low relative humidity air movement

Question 78

What is volatilization in terms of a pesticide?

Answer 78

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

Question 79

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

Answer 79

Lower Less

Question 80

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

Answer 80

Vapor Pressure Henry's Law of Constant

Question 81

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

Answer 81

Henry’s Law Constant

Question 82

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

Answer 82

10%

Question 83

Generally, toxicologically significant metabolites are simulated as _______ chemicals.

Answer 83

Independent

Question 84

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

Answer 84

Degradation or transformation

Question 84

______ 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.

Answer 84

Degradation

Question 85

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

Answer 85

Degradation Rate

Question 86

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

Answer 86

True

Question 87

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. ​

Answer 87

Half-life

Question 87

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

Answer 87

DT50 and DT90

Question 88

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

Answer 88

False - they do not

Question 89

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

Answer 89

(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)​

Question 89

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.​

Answer 89

Kinetics models

Question 90

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?

Answer 90

PESTDF from EPA & CAKE from Syngenta

Question 91

What does FOCUS stand for?

Answer 91

Forum for Coordination of pesticide fate models and their use

Question 92

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

Answer 92

First Order Patterns

Question 93

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

Answer 93

SFO

Question 94

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

Answer 94

DFOP

Question 94

FOMC

Answer 94

First-Order Multi-Compartmental Model