Download Chlorophyll

Light – life energy source
Light absorbed, reflected and transmitted
Absorption spectrum of Chlorophyll a
Absorption and action spectra (role of
accessory pigments)
Primary productivity
Chlorophyll a
Chlorophyll at the sea-surface in Eilat
Sea-surface Chlorophyll (Observatory Pier, daily)
4.0
3.5
ugr Chl / L
3.0
2.5
2.0
1.5
1.0
0.5
0.0
1988
1989
1990
1991
1992
1993
1994
1995
Year
1996
1997
1998
1999
2000
2001
2002
Measuring primary productivity
‫מדידת יצרנות ראשונית ונשימה ברמת החברה בבתי גידול‬
‫מימיים בשיטת החמצן‬
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Photosynthesis: 6CO2 + 6H2O  C6H12O6 + 6O2
Respiration:
C6H12O6 + 6O2 6CO2 + 6H2O
The goal: Determine the community's Gross Primary Productivity (GPP), the Net
Primary Productivity (NPP), and Respiration (R), all in [mg-C m-3 of water].
Since we measure C production and respiration indirectly, by measuring changes in
the concentration of dissolved oxygen, we need to convert masses of Oxygen to
Carbon. Note that photosynthesis generates 6 moles of O2 (192 gr-Oxygen / L) for
every 6 moles CO2 (72 gr-Carbon / L) that get fixed.
Thus a conversion factor needs to be used: 72/192 = 0.375
Also, since the efficiency of the process is about 86% (some 14% of the oxygen
produced is used for photosynthesis-related processed other than fixing carbon), an
equivalent ("Quotient") of 1.16 is used for the Oxygen-Carbon conversion
(1 / 1.16 = 0.86).
The Respiration Quotient (RQ) is 1.0 (since the source is a complete "burning" of
organic carbon)
‫מדידת יצרנות ראשונית ונשימה ברמת החברה בבתי גידול‬
‫ המשך‬- ‫מימיים בשיטת החמצן‬
Thus – if after T hours of incubation we measured Oxygen changes (mg/L) and
term these:
Il and Fl - the initial and final concentrations in the light bottle
Id and Fd- - the initial and final dark bottle
The following equations should be used:
Respiration rate (mg-C L-1 hr-1) = 0.375 * 1.0 * (Id – Fd) / T
Gross Primary Production (GPP) = 0.375 * 0.86 * [(Id-Fd) – (Il-Fl)] / T
Net Primary Production (NPP) = GPP - R
PI - Curve