**Cruise:** Cape Hatteras

**Dates:** May 17-26, 2006

**Chief Scientist:** Dr. Wei-Jun Cai, University of Georgia

**Equipment**: 12 bottle CTD with dual C, T, and O~2~ sensors and LADCP

**Number of Stations:** 64

**Ship:** R/V *Cape Hatteras*

**AOML CO~2~ Group Participant:** Heike Lueger

**[Chemical Measurements]{.underline}:**

**O~2~**: 140 samples taken in 120 ml iodine Erlenmeyer flasks, 20
duplicate samples.

PI: Dr. Chris Langdon, RSMAS

Analyzed by: George Berberian, AOML

O~2~ units are umol/kg

**Nutrients:** 146 samples taken in 8-ml vials, 30 duplicate samples

PI: Dr. Jia-Zhong Zhang, AOML

Analyzed by: Charles Fischer, AOML

Nutrient units are umol/kg

**DIC:** 35 stations, 149 samples each 500-ml, 14 duplicate samples

PI: Dr. Rik Wanninkhof, AOML

Analyzed by: Esa Peltola, AOML

DIC units are umol/kg

**TALK:** 12 stations, 32 samples, 0 duplicates

PI: Dr. Frank Millero, RSMAS

Analyzed by: Fen Huang, RSMAS

TALK units are umol/kg

**[Details]{.underline}:**

**DIC Sampling and Analysis**

DIC samples were taken in 500-ml ground glass-stoppered Pyrex bottles
and preserved with 0.2 ul of mercuric chloride solution. Samples were
transported to AOML for analysis. Analyses were performed following DOE
(1994).

Analysis Date: June 7-21, 2006

Coulometers used: AOML1 and AOML2

Blank range: 12.0-30.0 counts/min

CRM \# used and assigned value: Batch 59, c: 2007.10 umol/kg, S:33.316,

> Batch 66, c: 1969.57  umol/kg, S:32.962.

CRM value measured: AOML 1, Batch 59: offset 7.1 umol/kg (2000.0
umol/kg)

AOML 1: Batch 66: offset 5.3 umol/kg (1964.3 umol/kg)

> AOML-2: Batch 59: offset 6.8 umol/kg (2000.3 umol/kg)
>
> AOML-2: Batch 66: offset 7.5 umol/kg (1962.1 umol/kg)

The average run time was 13 minutes, the minimum run time was 8 minutes,
and the maximum run time was 20 minutes.

Reproducibility: (# samples and average difference): 7 sets of duplicate
samples; average difference = 1.5 umol/kg.

CRM, salinity and HgCl2 correction applied: yes

Location of analyses files: Esa\'s computer file/directory/name:

My Documents/SOMMA/Lab Studies/2006 (5) Heike

## DOE, 1994: Handbook of methods for the analysis of the various parameters of the carbon dioxide system in seawater, version 2.0 (A. Dickson and C. Goyet, eds.).

### O~2~ Sampling and Analysis

O2 samples were taken in 120 ml ground glass-stoppered Pyrex Erlenmeyer
flasks (iodine flasks). The samples were pickled with magnanous chloride
and sodium hydroxide. Sample bottles were stored under water. Samples
were transported to AOML for analyses.

Analysis Date: June 6-14, 2006

An automatic titration system was used for the oxygen analysis with the
Carpenter modification of the Winkler method using a photometric
determined endpoint. Reagents for the Carpenter method titration were
mixed by the AOML/OCD group of George Berberian as specified in
Friederich\'s MBARI Technical Report #91-6 (Friederich *et al.*, 1991).
Apparent oxygen utilization (AOU) is defined as O~2~ measured- O~2~
sat., where O~2~ sat. is the saturation value at potential temperature
and salinity of the sample determined according to Benson and Krause
(1984).

Reproducibility: (# samples and average difference): 10 sets of
duplicate samples;

average difference = 0.9 umol/kg:

  --------------------- ----------- ----------- ---------------- --------------
  **Station**           **Depth**   **O~2~**    **Difference**   **O~2~
                                                                 Average**

  A05                   51          175.4       0.3              175.5

  A05                   51          175.7                        

  B01                   2           218.5       0.2              218.4

  B01                   2           218.3                        

  B09/1                 3           206.2       0.1              206.3

  B09/1                 3           206.3                        

  C09                   33          216.9       0.4              217.1

  C09                   33          217.3                        

  C15/1                 461         138.4       0.2              138.3

  C15/1                 461         138.2                        

  D05                   25          186.4       0.5              186.1

  D05                   25          185.9                        

  D09                   26          212.2       0.3              212.4

  D09                   26          212.5                        

  D11/2                 2           201.2       3.9              199.2

  D11/2                 2           197.3                        

  E09                   100         179.8       3.3              181.5

  E09                   100         183.1                        

  E11/1                 101         177.7       0.3              177.9

  E11/1                 101         178.0                        

  **Average                                     **0.9**          
  Difference**                                                   
  --------------------- ----------- ----------- ---------------- --------------

Benson, B. B., and D. Krause, 1984: The concentration and isotopic
fractionation of oxygen dissolved in freshwater and seawater in
equilibrium with the atmosphere. *Limnol. Oceanogr.,* 29, 620-632.

Friederich, G.E., Codispoti, L.A., and C.M. Sakamoto, 1991: An
easy-to-construct automated Winkler titration system. MBARI Tech. Rept.
91-6.

#### Nutrient and Sampling Analysis

Analysis Date: June 5-8, 2006

Nutrient samples were taken from 10-L "Niskin" bottles in acid washed
25-ml linear polyethylene bottles after three complete seawater rinses
and stored frozen on board the ship. Frozen samples were brought back to
AOML and thawed to room temperature prior to analysis. Concentrations of
nitrite (NO2 ), nitrate (NO3 ), phosphate (PO~4~^-3^) and silicic acid
(H4SiO4) were determined using an Alpkem Flow Solution Auto-Analyzer.

[Nitrate and Nitrite]{.underline}:

Nitrite was determined by diazotizing with sulfanilamide and coupling
with N-1 naphthyl ethylenediamine dihydrochloride to form an azo dye.
The color produced is measured at 540 nm (Zhang *et al.,* 1997a).
Samples for nitrate analysis were passed through a home made cadmium
column (Zhang *et al.,* 2000), which reduced nitrate to nitrite and the
resulting nitrite concentration was then determined as described above.
Nitrate concentrations were determined from the difference of nitrate +
nitrite and nitrite.

[Phosphate]{.underline}:

Phosphate in the samples was determined by reacting with molybdenum (VI)
and antimony (III) in an acidic medium to form an
anti-monyphosphomolybdate complex at room temperature. This complex was
subsequently reduced with ascorbic acid to form a blue complex and the
absorbance was measured at 710 nm (Zhang *et al.,* 1998).

[Silicic Acid]{.underline}:

Silicic acid in the sample was analyzed by reacting the aliquot with
molybdate in an acidic solution to form β-molybdosilicic acid. The
β-molybdosilicic acid was then reduced by ascorbic acid to form
molybdenum blue (Zhang *et al.,* 1997b). The absorbance of the
molybdenum blue was measured at 660 nm.

[Calibration and Standards]{.underline}:

Stock standard solutions were prepared by dissolving high purity
standard materials (KNO3, NaNO2, KH2PO4, and Na2SiF6) in deionized
water. Working standards were freshly prepared by diluting the stock
solutions in low nutrient seawater. Low nutrient seawater was used for
the preparation of working standards. Determination of blank and wash
between samples was filtered seawater collected from the surface of the
Gulf Stream. Standardizations were performed prior to each sample run
with working standard solutions. The overall precision of the sample
analysis was 0.04 umol/kg for nitrate, 0.01 umol/kg for phosphate and
0.1 umol/kg for silicic acid.

Reproducibility: (# samples and average difference): 15 sets of
duplicate samples;

average difference: NO~2~+NO~3~ -- 0.18 umol/kg, SIO~3~ -- 0.05 umol/kg,
and PO~4~ -- 0.02 umol/kg:

  --------------- ----------- ----------------- ----------- ---------- ------------ ----------- ---------- ----------- ----------- ----------
  **Station**     **Depth**   **N0~2~+NO~3~**   **Diff.**   **Avg.**   **SIO~3~**   **Diff.**   **Avg.**   **PO~4~**   **Diff.**   **Avg.**

  E05             2           0.00              0.00        0.00       0.00         0.00        0.00       0.00        0.00        0.00

  E05             2           0.00                                     0.00                                0.00                    

  E09             100         5.70              0.00        5.70       0.00         0.00        0.00       0.27        0.01        0.26

  E09             100         5.70                                     0.00                                0.26                    

  E11/1           51          0.00              0.00        0.00       0.00         0.00        0.00       0.00        0.00        0.00

  E11/1           51          0.00                                     0.00                                0.00                    

  D07             11          0.00              0.00        0.00       0.00         0.00        0.00       0.00        0.00        0.01

  D07             11          0.00                                     0.00                                0.01                    

  D09             52          0.22              0.12        0.16       0.00         0.00        0.00       0.07        0.07        0.04

  D09             52          0.10                                     0.00                                0.01                    

  D11/1           386         21.51             0.65        21.19      6.56         0.18        6.47       1.28        0.01        1.28

  D11/1           386         20.86                                    6.38                                1.29                    

  C01             6           0.00              0.00        0.00       1.64         0.12        1.58       0.31        0.01        0.31

  C01             6           0.00                                     1.52                                0.32                    

  C09             2           0.00              0.00        0.00       0.00         0.00        0.00       0.05        0.00        0.05

  C09             2           0.00                                     0.00                                0.05                    

  C13             25          0.00              0.00        0.00       0.00         0.00        0.00       0.00        0.00        0.00

  C13             25          0.00                                     0.00                                0.00                    

  C15/1           461         28.72             0.56        28.44      15.70        0.04        15.68      1.69        0.04        1.67

  C15/1           461         28.16                                    15.66                               1.65                    

  C16/1           304         22.23             0.09        22.28      7.57         0.16        7.49       1.18        0.09        1.22

  C16/1           304         22.32                                    7.41                                1.27                    

  B03             16          0.00              0.00        0.00       0.00         0.00        0.00       0.08        0.00        0.08

  B03             16          0.00                                     0.00                                0.00                    

  B11/2           1203        32.87             1.27        32.24      17.53        0.17        17.62      1.85        0.05        1.88

  B11/2           1203        31.60                                    17.70                               1.90                    

  AO3             2           0.00              0.00        0.00       0.08         0.05        0.11       0.06        0.00        0.06

  A03             2           0.00                                     0.13                                0.07                    

  A08/1           2           0.00              0.00        0.00       0.00         0.00        0.00       0.00        0.00        0.00

  A08/1           2           0.00                                     0.00                                0.00                    

  **Average                                     **0.18**                            **0.05**                           **0.02**    
  Difference:**                                                                                                                    
  --------------- ----------- ----------------- ----------- ---------- ------------ ----------- ---------- ----------- ----------- ----------

Zhang, J-Z., P. B. Ortner, and C. Fischer, 1997a: Determination of
nitrite and nitrate in estuarine and coastal waters by gas segmented
continuous flow colorimetric analysis. In *Methods for the Determination
of Chemical Substances in Marine and Estuarine Environmental Matrices,
2nd Edition.* EPA-600-R-97-072, September 1997.

Zhang, J-Z., and G. A. Berberian, 1997b: Determination of dissolved
silicate in estuarine and coastal waters by gas segmented continuous
flow colorimetric analysis. In *Methods for the Determination of
Chemical Substances in Marine and Estuarine Environmental Matrices, 2nd
Edition*. EPA-600-R-97-072, September 1997.

Zhang, J.-Z., C. Fischer, and P. B. Ortner, 1999: Optimization of
performance and minimization of silicate interference in continuous flow
phosphate analysis. *Talanta*, 49(2):293-304.

# Zhang, J-Z., C. Fischer, and P. B. Ortner, 2000: Comparison of open tubular cadmium reactor and packed cadmium column in automated gas-segmented continuous flow nitrate analysis. *International Journal of Environmental Analytical Chemistry*, 76(2):99-113.