Phosphate balance and spatial variability on the continental shelf off the western US-Mexico border region
A cruise was conducted along the northwestern coast of Baja California, off the US-Mexico border region, to determine the physical, biological and anthropogenic factors affecting the concentration and distribution of phosphates (PO43–). The vertical distribution of temperature and PO43– sh...
| Autores: | , , , , , , |
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| Tipo de recurso: | artículo |
| Estado: | Versión publicada |
| Fecha de publicación: | 2007 |
| País: | México |
| Institución: | UNIVERSIDAD AUTÓNOMA DE BAJA CALIFORNIA |
| Repositorio: | Ciencias Marinas |
| Idioma: | inglés |
| OAI Identifier: | oai:cienciasmarinas.com.mx:article/1078 |
| Acceso en línea: | https://www.cienciasmarinas.com.mx/index.php/cmarinas/article/view/1078 |
| Access Level: | acceso abierto |
| Palabra clave: | phosphates upwelling mass balance pollution fosfatos surgencias balance de masas contaminación |
| Sumario: | A cruise was conducted along the northwestern coast of Baja California, off the US-Mexico border region, to determine the physical, biological and anthropogenic factors affecting the concentration and distribution of phosphates (PO43–). The vertical distribution of temperature and PO43– showed isograms (13ºC and 0.75 µM, respectively) rising towards the shore. Although this phenomenon was observed in all the study area, it was more abrupt in the southern part than in the northern, resulting in lower phosphate concentrations in the north (0.50 µM) associated with high chlorophyll a concentrations (10.0 mg m–3). A principal components analysis indicated that the PO43– concentrations were related to upwelling (51%) and phytoplankton biomass (23%). A PO43– mass balance indicated that sewage discharge had a very local effect, contributing 3.0 ± 0.12 t d–1 (5%), while horizontal advection contributed 20.0 ± 2.2 t d–1 (32%) and upwelling supply was 41.1 ± 2.3 t d–1 (63%). If the PO43– sewage contribution trend does not change, we predict that in 2035 the anthropogenic contribution will be as high as the amount delivered to the area by the Californian Current. Conversely, if Mexico´ s sewage treatment systems improve to a level similar to that in the USA, we estimate that by 2012 the anthropogenic sources will be insignificant. |
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