Rapid Communication / Communication RapideAmbient solar ultraviolet radiation and its effects on phosphorus flux into boreal lake phytoplankton communities

2002 ◽  
Vol 59 (7) ◽  
pp. 1090-1095 ◽  
Author(s):  
Paul C Frost ◽  
Marguerite A Xenopoulos
Keyword(s):  
Ultraviolet Radiation ◽  
P Uptake ◽  
Boreal Lakes ◽  
Particulate Phosphorus ◽  
Experimental Lakes Area ◽  
Solar Ultraviolet Radiation ◽  
Variable Effect ◽  
Phytoplankton Communities ◽  
P Flux ◽  
P Addition

We examined the effects of ultraviolet radiation (UVR) on net phosphorus (P) flux into phytoplankton communities in two boreal lakes at the Experimental Lakes Area (ELA), Canada. We manipulated P available to and irradiance received by phytoplankton during four different three-day incubations of dilution bioassays. Net P flux was estimated by measuring the accumulation of particulate P (that retained on glass fiber filters) over the incubation period. No effects of UVR on net P flux were found at ambient P levels in any of the experiments. At the highest levels of P addition, less particulate phosphorus (PP) accumulated in both the minus-UVB (~15–40%; photosynthetically active radiation (PAR) + UVA) and full-sunlight (~25–45%; PAR + UVA + UVB) exposed phytoplankton compared with those that received PAR only. Neither chlorophyll- nor carbon-specific net P flux was affected by UVR exposure at ambient P levels. However, at the highest levels of P enrichment, chlorophyll-specific net P flux increased in response to UVR in both lakes, whereas carbon-specific net P flux declined in one of the lakes and was unaffected by UV exposure in the second lake. Our results indicate that UVR can affect total PP accumulation in enriched systems, but not at ambient P levels, and that UVR has a weak and variable effect on biomass-specific P uptake in phytoplankton under enriched conditions.

Experimental Studies on the Effect of Arsenic on Microbial Degradation of Organic Matter and Algal Growth

1980 ◽  
Vol 37 (3) ◽  
pp. 415-423 ◽  
Author(s):  
G. J. Brunskill ◽  
B. W. Graham ◽  
J. W. M. Rudd
Keyword(s):  
Organic Matter ◽  
Microbial Degradation ◽  
Algal Blooms ◽  
Experimental Studies ◽  
Algal Growth ◽  
Inorganic Arsenic ◽  
P Uptake ◽  
Particulate Phosphorus ◽  
Experimental Lakes Area ◽  
Dissolved Phosphorus

Experiments were performed in tubes in Lake 303 at the Experimental Lakes Area to determine the effects of arsenate and arsenite on microbial degradation of organic matter, and to determine rates of reduction and oxidation of inorganic arsenic. Under winter ice, 40 μmol∙L−1 arsenate or arsenite inhibited microbial degradation of organic matter by 50%. Rates of oxidation of arsenite were about 2 μmol∙L−1∙d−1 under aerobic conditions, and rates of reduction of arsenate were about 1 μmol∙L−1∙d−1 under anaerobic conditions. During the ice-free season, arsenate and arsenite had little apparent effect upon rates of degradation of organic matter in lake tubes enriched with nutrients. Rates of formation of particulate phosphorus, and rates of planktonic uptake of dissolved phosphorus were depressed in the presence of arsenic. The observed rate of oxidation of arsenite in summer was similar to the winter value. Arsenate reduction rates ([Formula: see text]30 μmol∙L−1∙d−1) were very rapid under short periods of anaerobiosis. In the presence of large nutrient (N, P) concentrations, As did not inhibit the development of high algal biomass.Based on these experiments, we predict that addition of domestic sewage to arsenate-polluted Kam Lake (near Yellowknife, N.W.T.) will result in a state of restrained eutrophication. Degradation of organic matter will not be inhibited by As in summer, and dissolved phosphorus concentrations will remain high, due to As inhibition of P uptake by the plankton. During the summer, growth of algal blooms may be moderated by As, and more dissolved phosphorus will flow out of the lake to downstream waterbodies.Key words: arsenic, bacteria, algae, organic matter decomposition, eutrophication

Effects of solar ultraviolet radiation on epilithic metabolism, and nutrient and community composition in a clear-water boreal lake

2001 ◽  
Vol 58 (10) ◽  
pp. 2059-2070 ◽  
Author(s):  
Elise Marie Watkins ◽  
David W Schindler ◽  
Michael A Turner ◽  
David Findlay
Keyword(s):  
Ultraviolet Radiation ◽  
Stratospheric Ozone ◽  
Solar Spectrum ◽  
Taxonomic Composition ◽  
Experimental Lakes Area ◽  
Solar Ultraviolet Radiation ◽  
Northwestern Ontario ◽  
Boreal Lake ◽  
Algal Metabolism ◽  
Carbon And Nitrogen Content

Stratospheric ozone depletion, climate change, and acidification will increase the exposure of aquatic eco systems to ultraviolet radiation (UVR; 280–400 nm). The objective of this study was to determine the ecological effects of ambient UVR exposure on epilithon (algal communities attached to rocky substrata) relative to an artificially reduced UVR environment. UVR exposure was altered in the littoral zone of a boreal lake by selectively filtering segments of the solar spectrum with large acrylic sheets. This 130-day study took place at the Experimental Lakes Area, northwestern Ontario, in 1998. Epilithon were monitored for changes in productivity, biomass, pigment, and nutrient and taxonomic composition. The absence of UVR increased epilithic photosynthetic rates 37–46% above epilithon exposed to ambient UVR, increased cellular carbon and nitrogen content, and consequently lowered C:P. UVR effects on algal metabolism were dependent on seasonal trends. Epilithic respiration rates and chlorophyll a concentrations were not significantly different among treatments. A reduction in UV induced taxonomic shifts in epilithon, with diatoms increasingly favoured under low UV conditions. Species richness and diversity were not affected. Overall, the results of this study, considered together with previous research, suggest that the epilithic community is sensitive to changes in the UVR environment of aquatic ecosystems.

Simplified Calibration for Broadband Solar Ultraviolet Radiation Measurements¶

2003 ◽  
Vol 78 (6) ◽  
pp. 603 ◽  
Author(s):  
A. Oppenrieder ◽  
P. Hoeppe ◽  
P. Koepke ◽  
J. Reuder ◽  
J. Schween ◽  
...  
Keyword(s):  
Ultraviolet Radiation ◽  
Solar Ultraviolet Radiation ◽  
Solar Ultraviolet ◽  
Radiation Measurements

Spatiotemporal analysis of solar ultraviolet radiation based on Ozone Monitoring Instrument dataset in Iran, 2005–2019

2021 ◽  
pp. 117643
Author(s):  
Reza Gholamnia ◽  
Mehrnoosh Abtahi ◽  
Sina Dobaradaran ◽  
Ali Koolivand ◽  
Sahand Jorfi ◽  
...  
Keyword(s):  
Ultraviolet Radiation ◽  
Spatiotemporal Analysis ◽  
Ozone Monitoring Instrument ◽  
Solar Ultraviolet Radiation ◽  
Monitoring Instrument ◽  
Ozone Monitoring ◽  
Solar Ultraviolet

Measurement of solar ultraviolet radiation at a temperate and a tropical site using polysulphone film

1979 ◽  
Vol 1 (2) ◽  
pp. 121-132 ◽  
Author(s):  
A. Davis ◽  
B.V. Howes ◽  
K.J. Ledbury ◽  
P.J. Pearce
Keyword(s):  
Ultraviolet Radiation ◽  
Solar Ultraviolet Radiation ◽  
Solar Ultraviolet
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