The effect of the freshwater-sea transition on short-term dissolved organic carbon bio-reactivity : the case of Baltic Sea river mouths
(2014) In Student thesis series INES NGEM01 20132Dept of Physical Geography and Ecosystem Science
- Abstract
- Terrestrially-derived dissolved organic carbon (DOC) is transported to estuarine systems via river runoff, where it is largely degraded by microbial communities. I studied the combined influence of salinity (NaCl), microbial community (marine vs. freshwater) and inorganic nitrogen (N) and phosphorus (P) availability on DOC degradation rates in 10 major rivers in Sweden sampled during summer. The DOC degradation (inferred from dissolved O2 consumption rates) was determined on filtered river water during one week (7-days) in vitro experimental bioassays, applying the factors alone and in all possible combinations. Compared to the controls, addition of salt (10 psu) caused significant decreases in the DOC degradation in most cases, by 21-49%.... (More)
- Terrestrially-derived dissolved organic carbon (DOC) is transported to estuarine systems via river runoff, where it is largely degraded by microbial communities. I studied the combined influence of salinity (NaCl), microbial community (marine vs. freshwater) and inorganic nitrogen (N) and phosphorus (P) availability on DOC degradation rates in 10 major rivers in Sweden sampled during summer. The DOC degradation (inferred from dissolved O2 consumption rates) was determined on filtered river water during one week (7-days) in vitro experimental bioassays, applying the factors alone and in all possible combinations. Compared to the controls, addition of salt (10 psu) caused significant decreases in the DOC degradation in most cases, by 21-49%. In two cases, a significant P limitation was found, and a few additional rivers responded positively to P addition, although the effect was not statistically significant. Additions of N had no significant effect on the DOC degradation. Only one river – Pite älv – showed significant interactions effects between N and P, or N and S, but these effects were relatively small. Interactions between P and salt were found in two cases (Helgeån and Nyköpingsån).These interactions were strong and the results suggest that P additions significantly dampened the salt stress. Tests in which the microbial community was manipulated showed that salt stress was similar for both freshwater and marine microbes. In fact bacteria from the coast outside Malmö and ambient river mouth communities showed a similar negative response to salt additions. Finally, possible salt induced flocculation and particle formation was tested. According to results, there was no particle formation that significantly affected the DOC degradation rates. This study highlights the need for further studies of interactions between nutrient and salt concentrations on the fate of the terrestrially-derived DOC in the marine environment. (Less)
- Abstract (Swedish)
- Popular science
Dissolve organic carbon degradation in the estuarine environment
Dissolve Organic Carbon (DOC) is transported to the estuarine systems via river runoff where it is largely degraded by microbial communities. The availability of DOC effects aquatic ecosystems by causing changes in the bioavailability of toxic compounds, and by increasing the acidity of water . DOC degradation causes lowering of oxygen that severely effects the aquatic living organisms. In the water environment DOC degradation is limited by the presence of nitrogen (N) and phosphorous (P). But it is unclear if this applies to the Baltic Sea estuarine and coastal water. In this research work I have studied the combined influence of salinity (NaCl), microbial... (More) - Popular science
Dissolve organic carbon degradation in the estuarine environment
Dissolve Organic Carbon (DOC) is transported to the estuarine systems via river runoff where it is largely degraded by microbial communities. The availability of DOC effects aquatic ecosystems by causing changes in the bioavailability of toxic compounds, and by increasing the acidity of water . DOC degradation causes lowering of oxygen that severely effects the aquatic living organisms. In the water environment DOC degradation is limited by the presence of nitrogen (N) and phosphorous (P). But it is unclear if this applies to the Baltic Sea estuarine and coastal water. In this research work I have studied the combined influence of salinity (NaCl), microbial community and inorganic N and P availability on DOC degradation in 10 major rivers of Sweden. The samples were taken in summer 2013 for lab tests. The DOC degradation of filtered river water was determined from one week of lab experiment, by considering the regulating factors alone and in all possible combinations. Addition of salt caused significant decrease in the DOC degradation compared to the raw sample. In two cases, P significantly enhanced DOC degradation and few rivers responded positively to P addition although the effect was not statistically significant. Addition of N had no significant effect on the DOC degradation. Only one river – Pite älv – showed significant interaction effects between N and P, or N and S, but these effects were relatively small. Interactions between P and salt were found in two cases (Helgeån and Nyköpingsån). These interactions were strong and the results suggest that P addition significantly decreases the salt stress. Tests in which the microbial community was manipulated showed that salt stress was similar for both freshwater and marine microbes. In fact bacteria from the coast outside Malmö and ambient river mouth communities showed a similar negative response to salt additions. Finally, the possible salt induced flocculation and particle formation was tested. According to the results, there was no particle formation that significantly affected the DOC degradation rates. This study highlights the need of further studies about interactions between nutrient and salt concentrations on the fate of the terrestrially-derived DOC in the marine environment (Less)
Please use this url to cite or link to this publication:
http://lup.lub.lu.se/student-papers/record/4342479
- author
- Islam, Sohidul LU
- supervisor
- organization
- course
- NGEM01 20132
- year
- 2014
- type
- H2 - Master's Degree (Two Years)
- subject
- keywords
- estuary, microbial community, nutrients, degradation, DOC, reactivity, bioavailability, physical geography and ecosystems science
- publication/series
- Student thesis series INES
- report number
- 303
- funder
- Oscar & Lili Lamm's Foundation
- language
- English
- id
- 4342479
- date added to LUP
- 2014-03-04 12:55:25
- date last changed
- 2014-03-04 12:55:25
@misc{4342479,
abstract = {{Terrestrially-derived dissolved organic carbon (DOC) is transported to estuarine systems via river runoff, where it is largely degraded by microbial communities. I studied the combined influence of salinity (NaCl), microbial community (marine vs. freshwater) and inorganic nitrogen (N) and phosphorus (P) availability on DOC degradation rates in 10 major rivers in Sweden sampled during summer. The DOC degradation (inferred from dissolved O2 consumption rates) was determined on filtered river water during one week (7-days) in vitro experimental bioassays, applying the factors alone and in all possible combinations. Compared to the controls, addition of salt (10 psu) caused significant decreases in the DOC degradation in most cases, by 21-49%. In two cases, a significant P limitation was found, and a few additional rivers responded positively to P addition, although the effect was not statistically significant. Additions of N had no significant effect on the DOC degradation. Only one river – Pite älv – showed significant interactions effects between N and P, or N and S, but these effects were relatively small. Interactions between P and salt were found in two cases (Helgeån and Nyköpingsån).These interactions were strong and the results suggest that P additions significantly dampened the salt stress. Tests in which the microbial community was manipulated showed that salt stress was similar for both freshwater and marine microbes. In fact bacteria from the coast outside Malmö and ambient river mouth communities showed a similar negative response to salt additions. Finally, possible salt induced flocculation and particle formation was tested. According to results, there was no particle formation that significantly affected the DOC degradation rates. This study highlights the need for further studies of interactions between nutrient and salt concentrations on the fate of the terrestrially-derived DOC in the marine environment.}},
author = {{Islam, Sohidul}},
language = {{eng}},
note = {{Student Paper}},
series = {{Student thesis series INES}},
title = {{The effect of the freshwater-sea transition on short-term dissolved organic carbon bio-reactivity : the case of Baltic Sea river mouths}},
year = {{2014}},
}