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<h2>HPLC Pigment methods</h2>
<b>Method by Wright et al (Mar. Ecol. Prog. Ser. 1991, 77:183-196) CHLA1,
CHLA2, CHLB1 and CHLB2 estimated following the method of Latasa et al
(Mar. Chem. 1996, 51:315-324)</b>
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Pigment data for P2 & P5:
A comparison of the TURNER-determined chlorophyll a concentrations with the
HPLC-determined TOTCHLA concentrations (monovinyl chlorophyll a + divinyl
chlorophyll a + monovinyl chlorophyllide a; units = ng Chl a
equivalents/L) was performed for Process Cruise #2 (TTN-045) and Process
Cruise #5 (TTN-050). While good correlations were obtained for both
cruises, the slope obtained for Process Cruise #5 was significantly
different from 1 (i.e., TURNER > HPLC). This difference was probably
caused by the presence of Chl a-related pigments during Process Cruise #5.
Thus, we recommend that whenever possible use the HPLC pigment data and not
the TURNER pigment data. If HPLC data is not available for a given cast,
we further recommend that you use the following equations to transform the
TURNER data into HPLC-equivalent concentrations (cf., Babin, M., A. Morel,
H. Claustre, A. Bricaud, Z. Kolber and P.G. Falkowski. 1996. Nitrogen-
and irradiance-dependent variations of the maximum quantum yield of carbon
fixation in eutrophic, mesotrophic and oligotrophic marine systems.
Deep-Sea Research, in press).
Results of geometric mean regression analyses (reduced major axis):
Y = HPLC TOTCHLA (monovinyl chlorophyll a + divinyl chlorophyll a +
monovinyl chlorophyllide a), units = ng Chl a equivalents/L
X = TURNER chlorophyll a (it is necessary to convert the Turner Chl a
concentrations in the Arabian Sea data base from mg/m3 to ng/L by
multiplying concentrations by 1000)
(1) Process Cruise #2 (TTN-045)
HPLC TOTCHLA = TURNER*(0.975) + 4.833 (r = 0.9822, n = 146)
(2) Process Cruise #5 (TTN-050)
HPLC TOTCHLA = TURNER*(0.708) + 12.881 (r = 0.9772, n = 575)
Robert R. Bidigare
Department of Oceanography
University of Hawaii
Honolulu, HI 96822
808-956-6567 (voice mail)
808-956-9516 (fax)
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