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Clearing the Waters A focus on water quality solutions
Reproduction
This publication may be reproduced in whole or in part and in any form for educational or nonprofit purposes without special permission from the copyright holders, provided acknowledgement of the source is made. UNEP would appreciate receiving a copy of any publication that uses this publication as a source. No use of this publication may be made for resale or for any other commercial purpose whatsoever without prior permission in writing from the United Nations Environment Programme.
Clearing the Waters A focus on water quality solutions
Reproduction
This publication may be reproduced in whole or in part and in any form for educational or nonprofit purposes without special permission from the copyright holders, provided acknowledgement of the source is made. UNEP would appreciate receiving a copy of any publication that uses this publication as a source. No use of this publication may be made for resale or for any other commercial purpose whatsoever without prior permission in writing from the United Nations Environment Programme.
Effects of Heavy Metals on Cell Density, Size, Specific Growth Rate and Chlorophyll a of Tetraselmis Tetrathele Under Controlled Laboratory Conditions
Abstract
The effects of the varying levels of mercury (Hg) and cadmium (Cd) (0, 0.1, 0.3, 0.5, 1.0, 2.0, 3.0, 4.0 and 5.0 mg L⁻¹) to the cellular density of the green microalgae Tetraselmis tetrathele were evaluated every 24 h for 120 h. Specific growth rate, cell sizes and chlorophyll a were also monitored in the 5.0 mg L⁻¹ Hg and Cd and were compared to the unexposed at 0, 12, 24, 36, 48 and 120h. Results showed that the algal density of T. tetrathele exposed to various levels of Hg were similar with the control up to 48 h. Variations on different concentrations at different times were observed but the results suggest that T. tetrathele was not affected by Hg even at concentrations up to 5.0 mg L⁻¹ for 48 h but started to show toxicity from 3.0 to 5.0 mg L⁻¹ after 72 h and longer. Cd on the other hand also showed toxicity at 3.0, 4.0 and 5.0 mg L⁻¹ beyond 24 h exposure. The specific growth rate of T. tetrathele exposed to both 5.0 mg L⁻¹ Hg and Cd was statistically similar with those of the unexposed from 0 to 12 h and negative growth rates then followed up to 36 h. The chlorophyll a was significantly lower in the metal -exposed algae than did those unexposed. Chlorophyll a also decreased in T. tetrathele exposed to both heavy metals but algal cell sizes were not affected with the presence of Hg or Cd in the culture system.
Effects of Heavy Metals on Cell Density, Size, Specific Growth Rate and Chlorophyll a of Tetraselmis Tetrathele Under Controlled Laboratory Conditions
Abstract
The effects of the varying levels of mercury (Hg) and cadmium (Cd) (0, 0.1, 0.3, 0.5, 1.0, 2.0, 3.0, 4.0 and 5.0 mg L⁻¹) to the cellular density of the green microalgae Tetraselmis tetrathele were evaluated every 24 h for 120 h. Specific growth rate, cell sizes and chlorophyll a were also monitored in the 5.0 mg L⁻¹ Hg and Cd and were compared to the unexposed at 0, 12, 24, 36, 48 and 120h. Results showed that the algal density of T. tetrathele exposed to various levels of Hg were similar with the control up to 48 h. Variations on different concentrations at different times were observed but the results suggest that T. tetrathele was not affected by Hg even at concentrations up to 5.0 mg L⁻¹ for 48 h but started to show toxicity from 3.0 to 5.0 mg L⁻¹ after 72 h and longer. Cd on the other hand also showed toxicity at 3.0, 4.0 and 5.0 mg L⁻¹ beyond 24 h exposure. The specific growth rate of T. tetrathele exposed to both 5.0 mg L⁻¹ Hg and Cd was statistically similar with those of the unexposed from 0 to 12 h and negative growth rates then followed up to 36 h. The chlorophyll a was significantly lower in the metal -exposed algae than did those unexposed. Chlorophyll a also decreased in T. tetrathele exposed to both heavy metals but algal cell sizes were not affected with the presence of Hg or Cd in the culture system.
Investigation of The Quality of Water Treated by Magnetic Fields
Abstract
Passing water through a magnetic field has been claimed to improve chemical, physical and bacteriological quality of water in many different applications. Although the treatment process has been used for decades, it still remains in the realms of pseudoscience. If the claims of treating water with magnets are true, the process offers improvements on many of our applications of water in today’s world. A large number of peer reviewed journal articles have reported contradictory claims about the treatment.. Some of the most beneficial claimed water applications from magnetically treated water include improvement in scale reduction in pipes and enhanced crop yields with reduced water usage. Today we are still unsure whether the technology works and those who do believe it works are still trying to understand the mechanisms of how it works. Many research papers are starting to develop similar theories behind the mechanism of the treatment. From previous studies, it has been determined that the most successful MTD’s are those with alternating poles. The majority of the experiments performed during this research were determined to have insufficient controls to produce conclusive results. The conclusions from this research were focused on designing improved experiments to provide more conclusive results. A theory was developed to explain the MTD’s mechanisms of scale reduction. While the experimental results were not conclusive, the results attained backed the theory. Magnetically treated water does not do all that it is claimed it does. However, some of the positive results obtained during this research suggest that the improved experiments developed from this research may provide conclusive results on this controversial topic.
Investigation of The Quality of Water Treated by Magnetic Fields
Abstract
Passing water through a magnetic field has been claimed to improve chemical, physical and bacteriological quality of water in many different applications. Although the treatment process has been used for decades, it still remains in the realms of pseudoscience. If the claims of treating water with magnets are true, the process offers improvements on many of our applications of water in today’s world. A large number of peer reviewed journal articles have reported contradictory claims about the treatment.. Some of the most beneficial claimed water applications from magnetically treated water include improvement in scale reduction in pipes and enhanced crop yields with reduced water usage. Today we are still unsure whether the technology works and those who do believe it works are still trying to understand the mechanisms of how it works. Many research papers are starting to develop similar theories behind the mechanism of the treatment. From previous studies, it has been determined that the most successful MTD’s are those with alternating poles. The majority of the experiments performed during this research were determined to have insufficient controls to produce conclusive results. The conclusions from this research were focused on designing improved experiments to provide more conclusive results. A theory was developed to explain the MTD’s mechanisms of scale reduction. While the experimental results were not conclusive, the results attained backed the theory. Magnetically treated water does not do all that it is claimed it does. However, some of the positive results obtained during this research suggest that the improved experiments developed from this research may provide conclusive results on this controversial topic.
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