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Biogeochemical constraints on transparent exopolymeric particle production in a coastal bay of the Baltic Sea
2000 (English)Independent thesis Advanced level (professional degree), 20 credits / 30 HE creditsStudent thesis
Abstract [en]

The transparent Exopolymeric Particle (TEP) is a rather new kind of particle that have been observed and studied in marine systems during the last ten years. TEPs are formed from polysaccharides exuded by phytoplankton and due to their stickiness TEP can, through coagulation and aggregation with other elements, be essential for some sedimentation and flux processes in aquatic systems. Although TEPs are transparent they can be stained with alcian blue and thereby be made visible for counting in a microscope or quantified by spectrophotometry with Gum Xanthan as reference. In this project the abundance of TEP has been measured in Ekhagen in Stockholm, an inner coastal bay of the Baltic Sea. The measurements were preformed during winter and spring -2000. Between Jan 19th to May 19th a total of 46 samples were collected. The concentrations of TEP in Ekhagen were analyzed both by microscopy and by photospectrometry. To investigate if the presence of TEP had any impact on the biogeochemical conditions in Ekhagen, measurements of particulate organic carbon (POC), particulate organic nitrogen (PON), stable carbon isotope ratio (d13C), nitrogen isotope ratio (d15N), chlorophyll_a, chlorophyll_b, chlorophyll_c and phaeopigment were carried out simultaneous as the TEP analysis. The results from the spectrophotometric TEP quantification method showed that the concentrations of TEP in Ekhagen followed a two-phase pattern, i.e. the TEP concentrations were modest during winter (~160 [µg Xanthan equiv./L], mean value Jan to May) but increased rapidly as spring bloom progressed (~700 [µg Xanthan equiv./L], mean value May). POC and chlorophyll_a followed the same two-phase pattern as TEP and the concentrations of both chlorophyll_a and POC were found to correlate with the amount of TEP. We also found that the composition of particulate organic matter (POM) seemed to get enriched in carbon (compared to the normal POC/PON ratio in general plankton) as spring bloom progressed. This, along with the fact that (TEP) max ~ 870 [µg Xanthan equiv./L] and (POC) max ~1800 [µg/L], indicated that formation of TEP could have been a significant part of the POC origin in Ekhagen during algae bloom. The counting of TEP in microscope showed that the mean area of TEP increased as spring bloom progressed. This increase in TEP size was due to aggregation of TEP with other TEP and algae and it confirms the hypothesis that formation of TEP could be an important factor in sedimentation processes in aquatic systems.

Place, publisher, year, edition, pages
Keyword [en]
Technology, TEP, Transparent exopolymeric particles, phytoplankton, biogeochemistry, Chlorophyll_a, POC, Alcian Blue
Keyword [sv]
URN: urn:nbn:se:ltu:diva-54334ISRN: LTU-EX--00/274--SELocal ID: b48783e5-870a-4f64-80a0-4d9d9ac1b46cOAI: diva2:1027715
Subject / course
Student thesis, at least 30 credits
Educational program
Environmental Engineering, master's level
Validerat; 20101217 (root)Available from: 2016-10-04 Created: 2016-10-04Bibliographically approved

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