Dissolved organic carbon and nitrogen dynamics in the Douro River estuary, Portugal
Dissolved organic carbon (DOC) and dissolved organic nitrogen (DON) are metabolically important in estuaries. Their availability is influenced by organic matter inputs (internal and external) as well as by internal microbial transformations within the system. In this study, spatial and seasonal dyn...
| Main Authors: | , , , , , |
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| Format: | Article |
| Language: | English |
| Published: |
Universidad Autónoma de Baja California
2008-09-01
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| Series: | Ciencias Marinas |
| Subjects: | |
| Online Access: | https://www.cienciasmarinas.com.mx/index.php/cmarinas/article/view/1393 |
| _version_ | 1797279436923469824 |
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| author | C Magalhães C Teixeira R Teixeira A Machado I Azevedo AA Bordalo |
| author_facet | C Magalhães C Teixeira R Teixeira A Machado I Azevedo AA Bordalo |
| author_sort | C Magalhães |
| collection | DOAJ |
| description |
Dissolved organic carbon (DOC) and dissolved organic nitrogen (DON) are metabolically important in estuaries. Their availability is influenced by organic matter inputs (internal and external) as well as by internal microbial transformations within the system. In this study, spatial and seasonal dynamics of DOC and DON were evaluated in the Douro River estuary (Portugal). Monthly surveys were performed from October 2005 to December 2006 along a salinity gradient at three different depths. DOC and DON were calculated by subtracting the respective inorganic components (dissolved inorganic carbon, DIC, and dissolved inorganic nitrogen, DIN) from total dissolved carbon (TDC) and total dissolved nitrogen (TDN). In the Douro River estuary, DIC exhibits a linear and positive distribution as a function of salinity, indicating an input of DIC into the estuary from coastal waters. This pattern of distribution along the salinity gradient was also observed for total particulate matter, since a decreasing trend upstream was observed. In contrast, the results showed a general nonconservative behaviour of DOC along the estuarine transect during most months. This typical deviation from conservative mixing was mainly associated with sewage DOC sources into the lower and middle estuary. On average, DON concentrations represented 52–88% of the TDN. Along the transect, relationships between DIN and DON with salinity were generally conservative, decreasing towards the mouth, highlighting the fluvial source of such nitrogen forms; however, occasional DON sewage loads were registered. Estimated global Douro River watershed exports of DOC and DON to coastal waters yielded values of 420 kg C m–2 yr–1 and 125 kg N m–2 yr–1, respectively, which are high when compared with previously predicted levels from global models of DOC and DON export.
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| first_indexed | 2024-03-07T16:25:19Z |
| format | Article |
| id | doaj.art-10d9638622e9428cbfdc82ed57a8ecda |
| institution | Directory Open Access Journal |
| issn | 0185-3880 2395-9053 |
| language | English |
| last_indexed | 2024-03-07T16:25:19Z |
| publishDate | 2008-09-01 |
| publisher | Universidad Autónoma de Baja California |
| record_format | Article |
| series | Ciencias Marinas |
| spelling | doaj.art-10d9638622e9428cbfdc82ed57a8ecda2024-03-03T18:16:13ZengUniversidad Autónoma de Baja CaliforniaCiencias Marinas0185-38802395-90532008-09-0134310.7773/cm.v34i3.1393Dissolved organic carbon and nitrogen dynamics in the Douro River estuary, PortugalC Magalhães0C Teixeira1R Teixeira2A Machado3I Azevedo4AA Bordalo5Centre of Marine and Environmental ResearchCentre of Marine and Environmental ResearchCentre of Marine and Environmental ResearchCentre of Marine and Environmental ResearchCentre of Marine and Environmental ResearchCentre of Marine and Environmental Research Dissolved organic carbon (DOC) and dissolved organic nitrogen (DON) are metabolically important in estuaries. Their availability is influenced by organic matter inputs (internal and external) as well as by internal microbial transformations within the system. In this study, spatial and seasonal dynamics of DOC and DON were evaluated in the Douro River estuary (Portugal). Monthly surveys were performed from October 2005 to December 2006 along a salinity gradient at three different depths. DOC and DON were calculated by subtracting the respective inorganic components (dissolved inorganic carbon, DIC, and dissolved inorganic nitrogen, DIN) from total dissolved carbon (TDC) and total dissolved nitrogen (TDN). In the Douro River estuary, DIC exhibits a linear and positive distribution as a function of salinity, indicating an input of DIC into the estuary from coastal waters. This pattern of distribution along the salinity gradient was also observed for total particulate matter, since a decreasing trend upstream was observed. In contrast, the results showed a general nonconservative behaviour of DOC along the estuarine transect during most months. This typical deviation from conservative mixing was mainly associated with sewage DOC sources into the lower and middle estuary. On average, DON concentrations represented 52–88% of the TDN. Along the transect, relationships between DIN and DON with salinity were generally conservative, decreasing towards the mouth, highlighting the fluvial source of such nitrogen forms; however, occasional DON sewage loads were registered. Estimated global Douro River watershed exports of DOC and DON to coastal waters yielded values of 420 kg C m–2 yr–1 and 125 kg N m–2 yr–1, respectively, which are high when compared with previously predicted levels from global models of DOC and DON export. https://www.cienciasmarinas.com.mx/index.php/cmarinas/article/view/1393dissolved organic nitrogendissolved organic carbonDouro River estuary |
| spellingShingle | C Magalhães C Teixeira R Teixeira A Machado I Azevedo AA Bordalo Dissolved organic carbon and nitrogen dynamics in the Douro River estuary, Portugal Ciencias Marinas dissolved organic nitrogen dissolved organic carbon Douro River estuary |
| title | Dissolved organic carbon and nitrogen dynamics in the Douro River estuary, Portugal |
| title_full | Dissolved organic carbon and nitrogen dynamics in the Douro River estuary, Portugal |
| title_fullStr | Dissolved organic carbon and nitrogen dynamics in the Douro River estuary, Portugal |
| title_full_unstemmed | Dissolved organic carbon and nitrogen dynamics in the Douro River estuary, Portugal |
| title_short | Dissolved organic carbon and nitrogen dynamics in the Douro River estuary, Portugal |
| title_sort | dissolved organic carbon and nitrogen dynamics in the douro river estuary portugal |
| topic | dissolved organic nitrogen dissolved organic carbon Douro River estuary |
| url | https://www.cienciasmarinas.com.mx/index.php/cmarinas/article/view/1393 |
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