Homework answers / question archive / Use the attached graphs showing the vertical sections of dissolved inorganic carbon (DIC), carbonate alkalinity (ALK), dissolved total phosphate (PO3), dissolved nitrate (NO3), dissolved silicic acid (Si(OH)4) and dissolved oxygen (O2) to answer the following questions in the space provided: Write down the concentrations (mmol/kg) of the following chemical constituents at the given latitudes and depths: (Graph units  are umol/L) Chemical Constituent ATLANTIC 45oN, 100m ATLANTIC 30oN, 3000m ATLANTIC 45oS, 3000m PACIFIC 30oS, 3000m PACIFIC 30oN, 2000m DIC             ALK             PO4             NO3             Si(OH)4             O2               Write the CHANGE in the concentration (mmol/kg) of the following chemical constituents between the given latitudes and depths (roughly following thermohaline circulation)

Use the attached graphs showing the vertical sections of dissolved inorganic carbon (DIC), carbonate alkalinity (ALK), dissolved total phosphate (PO3), dissolved nitrate (NO3), dissolved silicic acid (Si(OH)4) and dissolved oxygen (O2) to answer the following questions in the space provided: Write down the concentrations (mmol/kg) of the following chemical constituents at the given latitudes and depths: (Graph units  are umol/L) Chemical Constituent ATLANTIC 45oN, 100m ATLANTIC 30oN, 3000m ATLANTIC 45oS, 3000m PACIFIC 30oS, 3000m PACIFIC 30oN, 2000m DIC             ALK             PO4             NO3             Si(OH)4             O2               Write the CHANGE in the concentration (mmol/kg) of the following chemical constituents between the given latitudes and depths (roughly following thermohaline circulation)

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Use the attached graphs showing the vertical sections of dissolved inorganic carbon (DIC), carbonate alkalinity (ALK), dissolved total phosphate (PO3), dissolved nitrate (NO3), dissolved silicic acid (Si(OH)4) and dissolved oxygen (O2) to answer the following questions in the space provided:

1. Write down the concentrations (mmol/kg) of the following chemical constituents at the given latitudes and depths: (Graph units  are umol/L)

Chemical Constituent	ATLANTIC 45oN, 100m	ATLANTIC 30oN, 3000m	ATLANTIC 45oS, 3000m	PACIFIC 30oS, 3000m	PACIFIC 30oN, 2000m
DIC
ALK
PO4
NO3
Si(OH)4
O2

 

Write the CHANGE in the concentration (mmol/kg) of the following chemical constituents between the given latitudes and depths (roughly following thermohaline circulation). Express increases in concentration along circulation pathway as positive numbers (decreases as negative):

Change in Chemical Constituent	From ATLANTIC 45oN, 100m to ATLANTIC 30oN, 3000m	From ATLANTIC 30oN, 3000m to ATLANTIC 45oS, 3000m	From ATLANTIC 45oS, 3000m to PACIFIC30oS, 3000m	From PACIFIC 30oS, 3000m to PACIFIC 30oN, 2000m
DDIC
DALK
DPO4
DNO3
DSi(OH)4
DO2

2. What processes are responsible for the observed changes in each chemical constituent:

Chemical Change	Short description of the processes responsible for the changes observed along the thermohaline circulation pathway
DDIC
DALK
DPO4
DNO3
DSi(OH)4
DO2

3.  Evaluation of biomineral dissolution in the deep ocean. Using your knowledge of DIC and ALK relationships, calculate the change in DIC concentrations in the deep ocean (> 2000 m) due to carbonate dissolution. Compare these results to the changes in Si(OH)4 concentrations due to opal dissolution.  Calculate the ratio between carbonate/opal dissolution across each of the oceanographic sections. 

Change in Chemical Constituent	From ATLANTIC 30oN, 3000m to ATLANTIC 45oS, 3000m	From ATLANTIC 45oS, 3000m to PACIFIC30oS, 3000m	From PACIFIC 30oS, 3000m to PACIFIC 30oN, 2000m
DDIC due to Carbonate dissolution
DSi(OH)4 due to opal dissolution
DDIC / DSi(OH)4 (mmol/mmol)

 

1. How do these ratios change among different ocean regions?
   
   
    
2. In what section of the deep ocean does carbonate dissolution dominate over opal dissolution?
   
   
    
3. In what section of the deep ocean does opal dissolution dominate over carbonate dissolution?
   
   
   
   
    
4. What does this tell us about supply/recycling of biominerals in the deep ocean?
   
    

 

4. Stoichiometric relationships between elements associated with organic matter mineralization.  Calculate the change in DIC due to organic matter mineralization. Once you have done that for the four different sections calculate the ratios shown in the table below. Remember all units are the same (mmol/kg):

Change in Chemical Constituent	From ATLANTIC 45oN, 100m to ATLANTIC 30oN, 3000m	From ATLANTIC 30oN, 3000m to ATLANTIC 45oS, 3000m	From ATLANTIC 45oS, 3000m to PACIFIC30oS, 3000m	From PACIFIC 30oS, 3000m to PACIFIC 30oN, 2000m
DDIC due to OM degradation
DDICOM/DPO4
DNO3/DPO4
DO2/DPO4

 

Using these data write the stoichiometric ratios among all four constituents for each of the four sections.  Do the calculations per 1 mmol/kg of PO4 è In the style of the RKR Ratio

i.e., 106C:16N:1P:138O₂

 

Change in Chemical Constituent	From ATLANTIC 45oN, 100m to ATLANTIC 30oN, 3000m	From ATLANTIC 30oN, 3000m to ATLANTIC 45oS, 3000m	From ATLANTIC 45oS, 3000m to PACIFIC30oS, 3000m	From PACIFIC 30oS, 3000m to PACIFIC 30oN, 2000m
xC:yN:1P:wO2

 

Evaluate how the stoichiometries of these sections compares to the RKR ratio. What processes may explain these deviations?