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The role of nitrilotriacetic acid as a modyfying factor of phytoplankton growth

100%

Kosakowska A.

Oceanological Studies

1998

vol. 27

issue 1

61-68

The paper presents results of studies on the influence of fresh and aged for 6-12 months aqueous solutions of nitrilotriacetic acid (NTA) on the growth of phytoplankton cells. Axenic strain of unicellular algae Scenedesmus microspina (B2-76) and cyanobacteria Chroococcus minor (A-101) (Gleocapsa minor) were used in the experiments as test organisms. These or-ganisms are common in waters of the Gulf of Gdansk and are important components in the food chain. Concentration of chlorophyll a in test cultures served as a measure of the growth of phytoplankton cell studied. NTA, when added to the culture of Scenedesmus or Chroococcus in the concentration range from 1 to 50 mmol/dm3 exerted a strong growth promoting effect on the cells. NTA solutions aged for 9-12 months stimulated the growth of cyano-bacteria Chroococcus minor to a much larger extent than green algae Scenedesmus microspina. These results indicate that the biological activity of NTA, after long-term incubation as an aqueous solution, undergoes a considerable modification. The effects biological of the end products of such a modification depend on the time of adding of NTA, its initial, concentration as well as on the sensitivity of phytoplankton strains. It is concluded therefore that, the presence of NTA in estuarine and coastal waters may significantly affect the metabolism and growth of phytoplanktonic cells, especially cyanobacteria.

The effect of amino and polycarboxylic acids on the toxicity of cobalt to phytoplankton cells

86%

Kosakowska A.

Oceanological Studies

1996

vol. 25

issue 4

47-54

The effect of the amino acids l-cysteine (CYS-SH), l-aspartic acid (ASP-OH) and l-glutamic acid (GLU-OH), and of polycarboxylic acids (PCAs) on the biological activity of co-balt in cultures of Scenedesmus armatus (Chodat) and Synechocystis aquatilis (Sauvageau) was investigated. The influence of metal ions was determined by measurements of chlorophyll a content in the cultures and rates of carbon fixation by the phytoplankton cells. The addition of cobalt (2.5*10-6 M) to the cultures caused inhibition of growth, monitored by the chlorophyll a concentration and the photosynthetic rate of both green algae and cyano-bacteria. It was found that these acids significantly increased the chlorophyll a content in both algal species when treated with cobalt. Polycarboxylates, CYS-SH and ASP-OH also increased the rate of C-14 incorporation into algal cells in both cultures, whereas GLU-OH was effective in cultures of Synechocystis only.The results indicate that organic compounds, polycarboxylates and amino acids modify the biological activity of the cobalt. The environmental consequences of these processes are considered.

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2 Oceanological Studies

1 1998

1 1996

2 Kosakowska A.

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The role of nitrilotriacetic acid as a modyfying factor of phytoplankton growth

The effect of amino and polycarboxylic acids on the toxicity of cobalt to phytoplankton cells