The kinetics of UV-B induced photoinhibition of photosynthesis in the context of vertical mixing

Conference · Tue Jan 09 04:00:00 EST 1990 · EOS, Transactions, American Geophysical Union; (United States)

OSTI ID:6617408

Lesser, M P; Cullen, J J ^[1]

---

1. Bigelow Lab. for Ocean Sciences, W. Boothbay Harbor, ME (United States)

The effect of ultraviolet radiation on primary productivity is conventionally assessed by putting natural samples in containers with different transmission characteristics and measuring the effects of specified wavebands on the uptake of [sup 14]C-bicarbonate. In the marine environment, the waveband of principal importance is the middle ultraviolet (UV-B). Because the time scale of the experiment may not match the time scale of vertical mixing, it is implicitly or explicitly assumed that the relative reduction of photosynthesis associated with UV-B is independent of the duration of exposure. It this were true, vertical mixing in the surface layer of the sea would not change the effect of ultraviolet radiation on integral photosynthesis, even though it would have a profound effect on the per-cell exposures to UV. These assumptions are not supported for photoinhibition of photosynthesis by visible light, but the question is unresolved for UV-B. Here we examine the assumptions underlying the experimental assessment of photoinhibition in nature, with particular emphasis on the kinetics of UV-B induced photoinhibition of photosynthesis. It is shown that if photoinhibition is modeled as dose-dependent reduction in the instantaneous rate of photosynthesis, the relative reduction of [sup 14]C-bicarbonate uptake associated with UV-B exposure will increase with time. If, as suggested by published results, the process of photoinhibition is a function of irradiance as well as dose, models and interpretations become more complicated. We use previously published and new experimental results to demonstrate how experiments can overestimate UV-induced photoinhibition when incubation time is longer than the temporal scale of vertical mixing.

• OSTI ID: 6617408
• Report Number(s): CONF-9002174--
• Conference Information: Journal Name: EOS, Transactions, American Geophysical Union; (United States) Journal Volume: 71:2
• Country of Publication: United States
• Language: English

Related Subjects

560120* -- Radiation Effects on Biochemicals
Cells
& Tissue Culture
63 RADIATION, THERMAL, AND OTHER ENVIRON. POLLUTANT EFFECTS ON LIVING ORGS. AND BIOL. MAT.
BIOLOGICAL EFFECTS
CHEMICAL REACTIONS
ELECTROMAGNETIC RADIATION
ENVIRONMENT
INHIBITION
KINETICS
MIXING
PHOTOCHEMICAL REACTIONS
PHOTOSYNTHESIS
PRODUCTIVITY
RADIATIONS
REACTION KINETICS
SYNTHESIS
ULTRAVIOLET RADIATION