[newbie!]

1st of all i couldnt find a fitting sub- forum for this stuff so since i'm a undergrad i figured i'd post it here. (but if you can tell me a better place it might fit?)
the course its self it called "Environmental and ANalytical CHemistry" but i guess the environmental stuff doesnt really fit into the analytical sub-forum.

anyways questions:

1)Sketch a Pourbaix diagram for water and indicate where on the diagram can the condition be found for a volcanic lake through which SO2 percolates and for sewage water.
ok so i know the x and y axis (pH vs E) and i know toput in the boundaries for water stability.
i think SO2 (marked X) would give an acidic pH and sewage (marked Y) maybe alkaine?
this is what i have:
i know its wrong, but idk where the x and y should be?


2) Construct a diagram in which the species of mercury in seawater and in freshwater can be identified. The following possible mercury species have to be considered: HgCl2, Hg(OH)2, HgCl42−.
dont have much clue here. know the basic set up of pourbaix like axis and stuff but dont know where to start withthis q.

3) What is the molecular formula of CFC 11?
ok so add 90 = 101 so i have CF
i know the answer to this question is CFCl3 but i dont know where the Cl3 is coming from?

4) Explain why in many river estuaries mud flats are formed and why those sediments show higher concentrations of DDT than further upstream in the riverbed.
know how they're formed, but dont know why the ddt conc is higher...?

4b)
i think pH would be alkaline but idk how far up on the y-axis i'm supposed to go?
4c) How would iron behave when the colloids at the river mouth have a PZC of 2.0 ?
in my notes i have is pH<pHo the surface protonates, if pH>pHo the colloid is negative
in environmental situations pH is ~7. common situation iron develops positive surface.
so from that i assume Fe2+ or Fe3+, but again how do i know which.. like how far up the y axis do i go?
(d) Is it expected to find elemental iron and hexavalent iron in natural waters? Give your reasoning.
no clue
(e) Suggest how iron binds to clay minerals and humic acid.
not sure

5a) The sediment profile for the element lead in an undisturbed lagoon near a busy industrialised harbour is shown below.

for the 2 marker, i put that it wouldnt change? coz in my notes it says that Pb is not very redox active and sticks to particles in higer conc in the surface of the water.
but idk i guess the fact its polluted orsomething is impportant?
the 6 marker i put that at diferent locations the concs and presnce of elements and comoounds are different therefore various samples are required as the conditions of the environment need to be taken into acount. but i think i've misunderstood thequestion.
b) Describe and explain an analytical methodology if a lead sample is taken and assessed for the following:
(i) bioavailability,
(ii) its association to iron oxide particles,
(iii) for its fraction on ion exchange sites,
(iv) for its fraction bound in silicate minerals.
no clue

6a)A chemical company develops a new compound for use as a pesticide to be sprayed on crops. One of the breakdown products of this material is volatile and needs to be tested for environmental impact.
(i) How can you determine whether this compound is a potential greenhouse gas? Describe and explain a method that gives qualitative and quantitative information on its greenhouse potential.
if it absorbs uv radiation it is a potential greenhouse gas.
dunno bout the tests?
(ii)Which properties determine whether this compound may also act as an ozone depleter in the stratosphere?
no clue
What are the major pollutants ejected into the atmosphere by volcanic eruptions? Name five major pollutants and their environmental impact.
from my notes the 5 pollutants were:
SO2, CO2, HCl, HF and Hg
not sure about impacts?

hope you can help