LECTURES 9-12 + TBL 3

Question 1

One of the most valuable wild salmon fisheries.

Answer 1

Pebble Mine in Bristol Bay, Alaska

Question 2

Cu toxicity is difficult to predict and depends on

Answer 2

Presence of chelating ligands, hard vs. soft water, transport (wind, currents, etc.)

Question 3

Copper is more toxic in ______ than in _____ waters because _____ waters have enhanced complexation capacity by _______, ______ and _____ which produce chelating ligands that bind to metals. ______ also produce ________ in response to Copper stress. This makes Copper less ______ in these waters

Answer 3

oligotrophic, eutrophic, eutrophic, fungi, cyanobacteria, algae, phytoplankton, phytochelatins, bioavailable

Question 4

Proteins that complex to copper that are made by phytoplankton

Answer 4

phytochelatins

Question 5

Chelating ligands that have a very high binding constant to metals

Answer 5

Metallotioneins

Question 6

With hard water, there is a lot of _____, which competes with copper for ___ _____ ___ on organisms such as salmon, thus _____ toxicity of dissolved copper. Thus, in ____ waters, even low copper concentrations can be lethal.

Answer 6

Ca2+, enzyme binding sites, reducing, soft

Question 7

Dissolved organic carbon contains many _____ ligands (ex. phytochelatins), which complexes with copper and typically ______ copper bioavailability

Answer 7

chelating, decreases

Question 8

The distribution of an element between its various chemical forms

Answer 8

Speciation

Question 9

The amount of a substance that can be in solution

Answer 9

Solubility

Question 10

In pure water, Pb can exist as soluble _____, or precipitate as _____. If carbonates are available, Pb can also precipitate as _____. In the presence of NTA, Pb can exist as soluble _______. Thus, NTA ____ the solubility of Pb

Answer 10

Pb2+, Pb(OH)2, PbCO3, Pb(NTA), increases

Question 11

Above the maximum ____ of Pb under a certain ______, adding more Pb will shift the equilibrium towards _____-

Answer 11

solubility, pH, Pb(OH)2

Question 12

By lowering the _______, chelation can increase the _____ of metals from solids

Answer 12

[free metal], solubility

Question 13

Chelation depends on

Answer 13

Stability of the metal chelate (Kf), [chelater] = [L], pH, presence of other cations, solubility of the metal complex, and solubility of the chelated metal complex

Question 14

The solid that allows the ______ maximum free metal under the conditions found in the environment is the least ______ solid, and the one that will form

Answer 14

least, soluble

Question 15

If the calculated free ______ in the presence of NTA or CO3 is ______ than maximum free Pb there is no _____. However, if _____ is greater than the maximum free Pb without NTA, it will.

Answer 15

Pb2+, lower, precipitation, total

Question 16

Other cations _____ with Pb2+ for NTA complexation. The most common is ____.

Answer 16

compete, Ca2+

Question 17

The real environment is very ____ and may require looking at the ___ species before the _____ interactions, and putting them into computer programs

Answer 17

complex, major, minor

Question 18

Reduction of O2 by organic matter (CH2O), can result in _____ (respiration)

Answer 18

O2 depletion/anoxic waters

Question 19

Wastewater treatment relies on oxidation of _____ but other oxidation reactions can cause things like iron rust

Answer 19

sewage

Question 20

Under anoxic conditions, C is reduced to _______ (methanogenesis)

Answer 20

CH4

Question 21

Involve changes in the oxidation state of the reactants

Answer 21

oxidation/reduction

Question 22

In the electrochemical cell, the _____ is oxidation, while the _____ is reduction. By convention all half reactions are defined as _____ reactions relative to the standard hydrogen electrode

Answer 22

anode, cathode, reduction

Question 23

A measure of how far a reaction mixture is from equilibrium; the greater the potential difference between the reduction and oxidation reactions, the stronger the “push” on a charged particle travelling between those points

Answer 23

Ecell

Question 24

Degree to which electrons are driven from the anode to the cathode; represents the availability of electrons in solution

Answer 24

Electron activity

Question 25

_____ electron activity and consequently, ____ pe, means greater electron ____ and thus a _____ environment, A ____ electron activity and consequently ______ pe, results in an _____ environment

Answer 25

high, low, pressure, reducing, low, high, oxidizing

Question 26

the ____ often has high pe, and therefore most species are in their oxidized forms, such as _____, ____, ___ and _____. ___ /____ exchange with the atmosphere and ____ keep the conditions _______

Answer 26

surface, NO3, SO4, Fe(OH)3, MnO2, CO2/O2, photosynthesis, oxidizing

Question 27

The ______ often has low pe and therefore most species are in their reduced forms, such as _____, _____, _____ and ____. ____ and _____, keep waters suboxic or _____

Answer 27

deep, NH4, H2S, Fe2+, Mn2+, respiration, microbial action, anoxic

Question 28

A more ______ E0 and pe0 leads to a greater tendency for reaction to proceed as written (reduction)

Answer 28

positive

Question 29

parameters that are fixed for a given environment and can be used to predict the distribution of various chemical species - such as pe and ph

Answer 29

environmental parameters

Question 30

At equilibrium in an electrochemical cell, ___ =K, and pe = _____, therefore, there is not net _____ flow at equilibrium

Answer 30

Q, 0, electron

Question 31

At a specific pH, the pe must be less than or equal to _______ and greater or equal to _____ for water to exist in equilibrium with the atmosphere,

Answer 31

20.75 - pH, -pH

Question 32

Above the oxidation limit for water, water is reduced to ______, and all dissolved species will be in the most ____ form

Answer 32

O2, oxidized

Question 33

In oxic environments, the _____ couple controls the pe

Answer 33

O2/H2O

Question 34

In anoxic waters, you must look at the species that are present such as _______, which you can assume are present in equal amounts. However, in high sulphate environments such as _____, the pe is controlled by the ____ couple

Answer 34

CO2/CH4, seawater, SO4/H2S

Question 35

At intermediate, ____ environments, the pe can be controlled by a variety of options such as ______, _____, _____, although nitrogen is usually not abundant enough. ______ and _____ may also be used

Answer 35

suboxic, NO3/NO2, NO3/N2, NO3/NH4, FeOOH/Fe2+, MnO2/Mn2+

Question 36

Reducing conditions are more common at depth in lakes that don’t ______. pe depends on the rate of _____ consumption (from sinking organic matter) vs ________. The pe helps us determine how _______ themselves in natural water species, and the species expected to exist at ____ under these conditions

Answer 36

overturn, O2, supply, redox species distribute themselves, equilibrium

Question 37

Most waters go from ___ to ____ with no inbetween because there are no ____ couples that control this environment

Answer 37

oxic, anoxic, redox

Question 38

Environments that are high in pe and low in pH

Answer 38

acid mine waste

Question 39

rain, lakes are generally ____ pe and _____ ph

Answer 39

high, middle

Question 40

rivers and oceans are generally _____ pe and ____ pH

Answer 40

middle, slightly higher

Question 41

submerged soils and swamps are generally ____ pe and ____ pH, controlled by the ____ couple

Answer 41

low, low, CO2/CH4

Question 42

marine sediments are generally _______ pe, and ____ pH, and controlled by the ______ couple

Answer 42

low, middle-high, SO4/H2S

Question 43

A chelator which 6 binding sites that is a common additive and causes issues in the environment

Answer 43

EDTA

Question 44

A chelator that is a common pollutant, used in water treatment and water softening

Answer 44

polyphosphates

Question 45

Natural chelators that breakdown products of biogenic materials; many specific complexes

Answer 45

humic substances

Question 46

A chelator that has 4 binding sites

Answer 46

NTA (nitrilotriacetic acid)

Question 47

Salts of polymeric phosphate species are used for _______ (to remove Ca2+), and _______ builders (sodium)

Answer 47

water softening, detergent

Question 48

PO4(3-)

Answer 48

orthophosphate

Question 49

H4P2O7

Answer 49

pyrophosphoric acid / phosphoric acid

Question 50

H5P3O10

Answer 50

triphosphoric acid

Question 51

With a longer phosphate chain, the ______ is very small, because it is more easily going to lose the first ______. Chain phosphates are very good _____

Answer 51

pka1, proton, chelators

Question 52

Polymeric phosphates can ____ to form simpler ______ species, such as from pyrophosphoric acid to _____. This reaction is catalyzed by _____ and other microorganisms. Because polymeric phosphates undergo this reaction rapidly, they are less of a problem in _____ _______ transport than NTA, EDTA and other organic ligands. However, the breakdown products such as _____ can be harmful in other ways, such as leading to ________, especially if P is the limiting nutrient. This prevents _____ from passing through for photosynthesis. Additionally, sinking of ______ _____ results in O2 consumption, causing deeper waters to become _______

Answer 52

hydrolyze, biodegradable, orthophosphoric acid, algae, heavy metal, HPO4, eutrophication, sunlight, organic matter, anoxic

Question 53

Humic substances are _____ in molecule weight (macromolecules), form during decomposition of _______, and. are classified into 3 groups on the basis of _______. The type depends on which _____ are present. They all have a _____ skeleton, high degree of _____ character, and many _______

Answer 53

high, vegetation, solubilities, plants, C, aromatic, functional groups

Question 54

When extracted with a strong base, the insoluble compound is _______, which is the highest in molecular weight. When the remaining solution is extracted with acid, the compound that is insoluble is _______, which is also high in molecular weight. The soluble compound is _____ acid which is low in molecular weight

Answer 54

humin, humic acid, fulvic acid

Question 55

Terrestrial and _____ humic substances are very different, and what forms also depends on ______, as this results in a smaller compound. This will determine the _______ character and the number of ________. ____ humic have more _____ character due to more _____ (woody blocks of trees and bushes)

Answer 55

ocean, degradation, aromatic, functional groups, aromatic, lignin

Question 56

Woody blocks of trees and bushes that increase aromatic character in terrestrial humics

Answer 56

lignin

Question 57

humic substances have functional groups with mostly ____, ____ and _____, such as ____ and ______. However, the ____ can be hard to determine as the rest of the molecule is very variable.

Answer 57

N, O, S, carboxyl, hydroxyl, pka

Question 58

A range of simple ____ molecules end up in natural waters due to decomposition of humic substances, such as ______, syringaldehyde, and 3,5-dihydroxo-benzoic acid

Answer 58

organic, catechol

Question 59

Humic substances have a strong effect on chemistry of natural waters, as it can bind metals by chelation with _____ and ____ group, or by 2 _______ groups, or just complexation with a ____ group. It binds ___ and ____ very strongly and _____, _____, ____, and ___ less strongly

Answer 59

carboxyl, hydroxyl, carboxyl, carboxyl, Fe, Al, Ni, Ca, Zn, Pb

Question 60

NTA has _____ exchangeable protons, meaning ___ will determine how good of a chelate it is. It is used in many ______ and can _____ and _____ heavy metal ions

Answer 60

3, pH, detergents, solubilize, transport

Question 61

______ of a chelating agent affects complexation, because the _____ compete with the metal for donor atoms.

Answer 61

protonation, protons

Question 62

Pka1 and pka2 of _____ are very close together, so ____ species must be considered in the range between pH ______. However, ______ is dominant over most natural pH range ______. From pH______, you only need to consider this species

Answer 62

NTA, 3, 1-4, H(NTA), 3-10, 5-8