The response of planktonic phosphate uptake and turnover to ultraviolet radiation in Lake Erie

2002 ◽  
Vol 59 (5) ◽  
pp. 778-786 ◽  
Author(s):  
C D Allen ◽  
R E.H Smith
Keyword(s):  
Ultraviolet Radiation ◽  
Lake Erie ◽  
Radiation Treatment ◽  
Phosphate Uptake ◽  
Ultraviolet B ◽  
Phosphate Limitation ◽  
Bacterial Cells ◽  
Near Surface ◽  
Ambient Concentrations ◽  
Uptake Activity

The hypothesis that ambient ultraviolet radiation (UVR), at near-surface intensities, may diminish phosphorus availability to phytoplankton was tested in Lake Erie in July and August of 1998 and 1999. Relative to samples exposed to photosynthetically active radiation (PAR, 400–700 nm) only, those exposed to ultraviolet-B (UVB, 280–320) and (or) ultraviolet-A (UVA, 320–400 nm) in natural sunlight, or kept in darkness, had diminished phosphate uptake rates at elevated (1 µM P) dissolved phosphate concentrations. By contrast, the specific uptake rate of dissolved phosphate at ambient concentrations (turnover rate) was not significantly affected by UVR or darkness. Turnover was usually dominated by particles smaller than 0.8 µm, whereas uptake from elevated concentrations was dominated by larger particles. The size distribution of turnover and uptake activity was not affected by radiation treatment. Chlorophyll a concentrations were decreased by sufficient exposure to UVB and (or) UVA and increased by deprivation of PAR (dark controls), but the concentration of bacterial cells was unaffected. The results showed that UVR inhibited the phosphate uptake potential of larger, probably algal, plankton but did not change the apparent severity of phosphate limitation at ambient concentrations.

Atmospheric transport and deposition of trace elements to lake erie from Urban areas

1996 ◽  
Vol 33 (4-5) ◽  
pp. 259-265
Author(s):  
Gerald J. Keeler ◽  
Nicola Pirrone
Keyword(s):  
Trace Elements ◽  
Urban Areas ◽  
Lake Erie ◽  
Atmospheric Transport ◽  
Spatial And Temporal Variation ◽  
Deposition Flux ◽  
Emission Sources ◽  
Dry Deposition Flux ◽  
Ambient Concentration ◽  
Ambient Concentrations

A hybrid receptor-deposition (HRD) modeling approach was used to determine the spatial and temporal variation in the ambient concentration and dry deposition flux of trace elements on fine (< 2.5 mm) and coarse (> 2.5 mm) particulate matter over Lake Erie. Upper-air observations from the National Weather Service (NWS) and ambient concentrations measured at two sampling sites downwind of major emission sources in the Lake Erie basin were input to the model. An evaluation of the deposition flux of size-segregated trace elements to the lake during the over-water transport was performed. The average total (fine + coarse) deposition flux was 9.6 ng/m2-h for V, 70 ng/m2-h for Mn, 3.2 ng/m2-h for As, 4.2 ng/m2-h for Se, 10 ng/m2-h for Cd, and 43.3 ng/m2-h for Pb.

The stability of the stratospheric ozone layer during the end-Permian eruption of the Siberian Traps

2007 ◽  
Vol 365 (1856) ◽  
pp. 1843-1866 ◽  
Author(s):  
David J Beerling ◽  
Michael Harfoot ◽  
Barry Lomax ◽  
John A Pyle
Keyword(s):  
Organic Matter ◽  
Transport Model ◽  
Stratospheric Ozone ◽  
Ultraviolet B ◽  
Large Reservoir ◽  
Near Surface ◽  
Siberian Traps ◽  
Northern Latitudes ◽  
The Stability ◽  
Mutagenic Effects

The discovery of mutated palynomorphs in end-Permian rocks led to the hypothesis that the eruption of the Siberian Traps through older organic-rich sediments synthesized and released massive quantities of organohalogens, which caused widespread O 3 depletion and allowed increased terrestrial incidence of harmful ultraviolet-B radiation (UV-B, 280–315 nm; Visscher et al . 2004 Proc. Natl Acad. Sci. USA 101 , 12 952–12 956). Here, we use an extended version of the Cambridge two-dimensional chemistry–transport model to evaluate quantitatively this possibility along with two other potential causes of O 3 loss at this time: (i) direct effects of HCl release by the Siberian Traps and (ii) the indirect release of organohalogens from dispersed organic matter. According to our simulations, CH 3 Cl released from the heating of coals alone caused comparatively minor O 3 depletion (5–20% maximum) because this mechanism fails to deliver sufficiently large amounts of Cl into the stratosphere. The unusual explosive nature of the Siberian Traps, combined with the direct release of large quantities of HCl, depleted the model O 3 layer in the high northern latitudes by 33–55%, given a main eruptive phase of less than or equal to 200 kyr. Nevertheless, O 3 depletion was most extensive when HCl release from the Siberian Traps was combined with massive CH 3 Cl release synthesized from a large reservoir of dispersed organic matter in Siberian rocks. This suite of model experiments produced column O 3 depletion of 70–85% and 55–80% in the high northern and southern latitudes, respectively, given eruption durations of 100–200 kyr. On longer eruption time scales of 400–600 kyr, corresponding O 3 depletion was 30–40% and 20–30%, respectively. Calculated year-round increases in total near-surface biologically effective (BE) UV-B radiation following these reductions in O 3 layer range from 30–60 (kJ m −2  d −1 ) BE up to 50–100 (kJ m −2  d −1 ) BE . These ranges of daily UV-B doses appear sufficient to exert mutagenic effects on plants, especially if sustained over tens of thousands of years, unlike either rising temperatures or SO 2 concentrations.

Photoinhibition of natural phytoplankton assemblages in Lake Erie exposed to solar ultraviolet radiation

2000 ◽  
Vol 57 (2) ◽  
pp. 371-379 ◽  
Author(s):  
Christopher A Marwood ◽  
Ralph EH Smith ◽  
John A Furgal ◽  
Murray N Charlton ◽  
Keith R Solomon ◽  
...  
Keyword(s):  
Lake Erie ◽  
Pulse Amplitude ◽  
Ultraviolet B ◽  
Surface Radiation ◽  
Low Light ◽  
Solar Ultraviolet Radiation ◽  
Phytoplankton Assemblages ◽  
Photosystem Ii Efficiency ◽  
Kinetics Of ◽  
Modulated Chlorophyll Fluorescence

Photoinhibition was examined in natural assemblages of phytoplankton from Lake Erie exposed to ambient solar radiation. The impacts on photosynthesis of photosynthetically active radiation (400-700 nm) (PAR), ultraviolet-A radiation (320-400 nm) (UVA), and ultraviolet-B radiation (295-320 nm) (UVB) were assessed at three sites on the lake using pulse amplitude modulated chlorophyll fluorescence. Short exposures (<= 30 min) to sunlight containing UVB (1.8-4.4 mmol·m-2) resulted in the rapid loss of up to 60% of photosystem II efficiency (in the dark-adapted state) (Fv/Fm) and quantum yield (in the light-adapted state) (ΔF/F'm). Exposure to UVA (46-105 mmol·m-2) generally diminished Fv/Fm and, to a lesser extent, ΔF/F'm. Short exposures to PAR (733-1588 mmol·m-2) had no significant effects on electron transport. Recovery from UVA- or UVB-induced photoinhibition was complete for Fv/Fm and 90% complete for ΔF/F'm after 2 h in low light. The results indicate that exposures of phytoplankton to surface radiation need only be short in duration to cause substantial UV inhibition of photosynthesis. However, depending on the kinetics of mixing of the water column, recovery of photosynthesis is possible if there is sufficient time for repair of UV damage. Future elevated levels of solar UVB due to ozone depletion could significantly inhibit primary production in mesotrophic lakes such as Lake Erie.

Physiological responses of natural plankton communities to ultraviolet-B radiation in Redberry Lake (Saskatchewan, Canada)

1997 ◽  
Vol 54 (3) ◽  
pp. 705-714 ◽  
Author(s):  
G A Ferreyra ◽  
S Demers ◽  
P A del Giorgio ◽  
J -P Chanut
Keyword(s):  
Electron Transport ◽  
Ultraviolet Radiation ◽  
Chlorophyll A ◽  
Transport System ◽  
Carbon Assimilation ◽  
Cell Number ◽  
Ultraviolet B ◽  
Electron Transport System ◽  
Experimental Conditions ◽  
Anthropogenic Modifications

Damaging effects of ultraviolet radiation on the aquatic biota, related to anthropogenic modifications in the ozone layer, have been extensively described. However, most of the research has focused on marine environments, and information about the effects of ultraviolet radiation on saline prairie lakes of Canada is lacking. To test the deleterious effects of ultraviolet-B (UV-B) radiation on the planktonic community, two exposure experiments were performed in Redberry Lake, Saskatchewan. The responses of primary productivity, phytoplankton chlorophyll a and size, bacterial changes, and the electron transport system to natural UV-B fluxes reaching the surface of the lake were studied. No clear effects of UV-B on phytoplankton carbon assimilation and chlorophyll a were observed. However, significant responses were found for the two phytoplankton size fractions studied (0.7-2 and >2 µm), which were more related to the experimental conditions than to UV-B effects. Bacteria presented a clear decrease in cell number under the highest UV-B doses, whereas the opposite was observed for the electron transport system activity.

scholarly journals Cumulative Effects of Ultraviolet Radiation and Photosyntheically Active Radiation on Phycobiliproteins of A Hot-Spring Cyanobacatrium Nostoc sp. strain HKAR-2

2016 ◽  
Vol 4 (3) ◽  
pp. 247-253
Author(s):  
Vinod K. Kannaujiya ◽  
Akhlaqur Rahman ◽  
. Adinath ◽  
Arun S. Sonker ◽  
Jainendra Pathak ◽  
...  
Keyword(s):  
Ultraviolet Radiation ◽  
Environmental Conditions ◽  
Photosynthetically Active Radiation ◽  
Biomedical Applications ◽  
Hot Spring ◽  
Ultraviolet B ◽  
Cumulative Effects ◽  
Key Factors ◽  
Active Radiation ◽  
Continuous Induction

Cyanobacteria are cosmopolitan in distribution and have adapted to diverse habitats. Adaptation of cyanobacteria is one of the key factors to withstand harsh environmental conditions. We have investigated the effects of photosynthetically active radiation (PAR; 400–700 nm), ultraviolet-B (UV-B; 280–315 nm) radiation and PAR+UV-B radiations on phycobiliproteins (PBPs) of a hot-spring cyanobacterium Nostoc sp. HKAR-2. There was a continuous induction of both phycoerythrin (PE) and phycocyanin (PC) after exposure of PAR up to 300 min. However, there was an induction in the synthesis of both PE and PC up to 240 min exposure of UV-B and PAR+UV-B radiations. Further exposure showed decline in the synthesis due to rapid uncoupling, bleaching and degradation of PBPs. Similarly, emission fluorescence also showed an induction with a shift towards longer wavelengths after 240 min of UV-B and PAR+UV-B exposure. These results indicate that short duration of UV radiation may promote the synthesis of PBPs that can be utilized in various biotechnological and biomedical applications. Int J Appl Sci Biotechnol, Vol 4(3): 247-253

scholarly journals Models for ultraviolet radiation-dependent photoinhibition of Lake Erie phytoplankton

2004 ◽  
Vol 49 (1) ◽  
pp. 202-214 ◽  
Author(s):  
Véronique P. Hiriart-Baer ◽  
Ralph E. H. Smith
Keyword(s):  
Ultraviolet Radiation ◽  
Lake Erie
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