Download or read book Influence of UVB Radiation on the Capacity of Dissolved Organic Carbon to Protect Freshwater Phytoplankton from Metal Toxicity written by Susan Winch and published by . This book was released on 2002 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Water samples from the Raisin River, Grand River, Lake Simcoe and St. Lawrence River were irradiated in the laboratory for up to 10 d under fluorescent lamps with maximum irradiance in the ultraviolet B waveband (at 310 nm). These waters were chosen to represent a range of dissolved organic carbon (DOC - 30.3, 17.4, 4.4 and 1.9 mg C L-1, respectively). Changes in toxicity of Cu, Zn, Co, Pb, Ni and Cd to Pseudokirchneriella subcapitata in response to irradiation depended on sample source and on the metal tested. Newington Bog water (35.5mg C L-1) was irradiated for 20 d under UVB lamps in the laboratory and under natural solar radiation. Further experiments were performed using a second sample of Raisin River water (20.7 mg C L-1) exposed to 20 d artificial UVA and UVB radiation at or below the maximum irradiance of natural solar radiation. (Abstract shortened by UMI.).
Download or read book The Influence of Dissolved Organic Carbon DOC and Calcium on the Toxicity of Copper and Nickel to the Freshwater Alga Selenastrum Capricornutum and the Zooplankter Daphnia Magna written by Ucu Rahayu and published by . This book was released on 2000 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: The toxicity of copper and nickel was measured in algal cultures of Selenastrum capricornutum and zooplankton cultures of Daphnia magna to determine if dissolved organic carbon (DOC) and/or calcium concentrations can influence toxicity of these two metals. Water samples were collected from the Raisin River (high DOC and high calcium), the St. Lawrence River (low DOC and high calcium), the Ottawa River (medium DOC and calcium) as well as two lakes in Nova Scotia. The concentration sufficient to kill half the population of Daphnia magna after 48h of exposure (LC50), and the inhibition of cell growth of S. capricornutum after 72 h of exposure (IC50) were used to determine the sensitivity of these species to copper or nickel toxicity in these 5 water samples. In Part 3, I showed that the protection against copper or nickel toxicity was reduced with UVB radiation even though the total DOC was reduced by only 18%. The role of EDTA in the toxicity of copper and nickel on S. capricornutum was investigated in part 4. (Abstract shortened by UMI.).
Download or read book Interactive Effects of Temperature Nutrient Availability and Dissolved Organic Carbon Concentrations on the Response of Alpine Phytoplankton Population Growth to Ultraviolet Radiation written by Shaina A. Doyle and published by . This book was released on 2005 with total page 96 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Release of UV absorbing Compounds by Marine Phytoplankton and Their Effect on the Absorption Properties of Particulate and Dissolved Organic Matter written by Kenia Whitehead and published by . This book was released on 1996 with total page 224 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Influence of Dissolved Organic Carbon on the Speciation Bioavailability and Toxicity of Metals to Aquatic Biota in Soft Water Lakes written by and published by . This book was released on 1997 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Selected Water Resources Abstracts written by and published by . This book was released on 1981 with total page 768 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Physiological Responses of Marine Organisms to Environmental Stresses written by Janet V. Dorigan and published by . This book was released on 1987 with total page 524 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Influence of Dissolved Organic Carbon on the Speciation Bioavailability and Toxicity of Metals to Aquatic Biota in Soft Water Lakes written by and published by . This book was released on 1997 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book The Interaction of Ultraviolet Radiation Dissolved Organic Carbon and Primary Production by Laurentian Great Lake Phytoplankton Communities written by Daniel T. Hamilton and published by . This book was released on 2011 with total page 140 pages. Available in PDF, EPUB and Kindle. Book excerpt: Man-made chemicals are continuing to erode the ozone layer, and recovery of the ozone layer is slow. Therefore aquatic ecosystems are continuing to receive elevated ultraviolet radiation (UVR). The aim of this work was to investigate and quantify the impact of ultraviolet light on photosynthesis at various near-shore Great Lakes sites (Hamilton Harbour, Lake Ontario, Bay of Quinte, Woods Bay, Georgian Bay) using both oxygen metabolism and carbon assimilation. Enhanced UVR suppressed primary production at all stations when compared to incubations with photosynthetically active radiation (PAR) only. The average decline in net O2 production was greater than 90% and sometime exceeded 100%; that is, enhanced UVR often produced net consumption of oxygen. Carbon was always assimilated with UVR+PAR exposure, although C- assimilation declined on average between 40 and 60% relative to PAR only, so there must have been some photosynthetic activity taking place as well as enhanced oxygen consumption. The oxygen consumption appears to be biotic, as tests for abiotic oxygen consumption failed to demonstrate any O2 loss. Dark respiration after 4-h light treatments with PAR or PAR+UVR was sometimes different, but not in a consistent way even at the same site. For example, at Hamilton Harbour on two occasions respiration after the PAR+ UVR exposure exceeded the PAR only treatments, while on the remaining dates dark respiration after the PAR- only treatments exceeded the PAR+UV treatment. While there is some evidence of enhanced dark respiration as a result of exposure during incubation in enhanced ultraviolet radiation, it appears that the decline in net photosynthesis is caused mainly be the decline in gross photosynthesis rather than an increase in respiration. Carbon assimilation was suppressed under enhanced ultraviolet radiation, and the degree of suppression was negatively related to the 14-day cumulative average of ultraviolet radiation (at 295 nm) prior to the experiment. I interpret this as evidence that phytoplankton to adapt to UVR exposure. Neither chlorophyll nor DOC appeared to be important factors. Bacterial productivity also responded to the PAR + UVR irradiation compared to the PAR alone incubations although the response appeared to vary with season. Experimental PAR + UVR incubations carried out during the mid season appeared to have higher production during the 12 h post-treatment dark incubation compared to incubations under PAR, while those from later in the season tended to respond with suppressed productivity in the PAR + UVR incubations compared to the PAR alone.
Download or read book Effects of Nutrients Photoinhibition Photoacclimation on Photosystem II Function of Freshwater Phytoplankton Communities written by Joel Harrison and published by . This book was released on 2011 with total page 142 pages. Available in PDF, EPUB and Kindle. Book excerpt: Electron flow through Photosystem II (PSII) is essential to all life on Earth. The efficiency of this process in freshwater phytoplankton can be depressed by nutrient limitation, ultraviolet radiation (UVR), and excessive photosynthetically active radiation (PAR). The effects of nutrients and radiation on PSII function of natural communities were assessed using changes in the variable fluorescence of PSII (PSII VF), as determined by a pulse amplitude modulation (PAM) fluorometer. The net susceptibility to photoinhibition of PSII depends upon the sensitivity of the assemblage to photodamage and the efficiency of recovery. Damage and recovery rates were quantified by fitting changes in FV:FM during experimental spectral exposures to the model of Kok (1956). Phytoplankton from deep chlorophyll maxima were found to exhibit much higher photosynthetic impairment under UVR exposure than epilimnetic communities in two lakes, due to differences in both damage and recovery rates. In six temperate lakes of the Dorset-Haliburton region, the susceptibility to UVR-induced photoinhibition of PSII was found to be a function of the water transparency (dissolved organic carbon content) of the systems from which the plankton were isolated, with no obvious taxonomic pattern to the responses. Nutrient (nitrogen & phosphorus) supplementation of communities from the Dorset Lakes and from Lake Ontario did not have strong effects on PSII VF, and did not alter the response of Lake Ontario phytoplankton to spectral irradiance. Diurnal changes in FV:FM of Lake Ontario phytoplankton were modeled and average values for the upper half of the water column showed reasonable agreement with observed data; however it is suggested that the addition of a model to simulate vertical mixing could improve the depth-specific accuracy of the predictions. It is concluded that the light history (photoacclimation status) of phytoplankton is the major determinant of the sensitivity of PSII to UVR, and that the nutrient status and taxonomic composition of phytoplankton communities have a comparatively minor influence.
Download or read book Impact of dissolved organic carbon phosphorus and grazing on phytoplankton biomass and production in experimental lakes written by S.R. CARPENTER and published by . This book was released on 1998 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Seasonal Variation in the Effects of Nutrient and Dissolved Organic Matter Concentrations on the Response of Phytoplankton Community Structure to Ultraviolet Radiation written by Caren E. Scott and published by . This book was released on 2006 with total page 54 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Effects of Dissolved Organic Carbon as a Bacterial Growth Substrate and as an Ultraviolet B Radiation Sunscreen for Aquatic Microbial Foodwebs in Mackenzie Delta Lakes Northwest Territories microform written by Christopher J. (Christopher John) Teichreb and published by National Library of Canada = Bibliothèque nationale du Canada. This book was released on 1999 with total page 392 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Pollution Abstracts written by and published by . This book was released on 1995 with total page 662 pages. Available in PDF, EPUB and Kindle. Book excerpt: Indexes material from conference proceedings and hard-to-find documents, in addition to journal articles. Over 1,000 journals are indexed and literature published from 1981 to the present is covered. Topics in pollution and its management are extensively covered from the standpoints of atmosphere, emissions, mathematical models, effects on people and animals, and environmental action. Major areas of coverage include: air pollution, marine pollution, freshwater pollution, sewage and wastewater treatment, waste management, land pollution, toxicology and health, noise, and radiation.
Download or read book Impact of Dissolved Organic Nitrogen on Freshwater Phytoplankton written by Dorothea Fiedler and published by . This book was released on 2016 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Implications of Phytoplanktonic Light Limitation in Stratified Lakes with Contrasting Dissolved Organic Carbon Content written by David L. Christensen and published by . This book was released on 1995 with total page 198 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Effects of Dissolved Organic Carbon as a Bacterial Growth Substrate and as an Ultraviolet B Radiation Sunscreen for Aquatic Microbial Foodwebs in Mackenzie Delta Lakes Northwest Territories written by and published by . This book was released on 1999 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
