Journal cover Journal topic
Hydrology and Earth System Sciences An interactive open-access journal of the European Geosciences Union
doi:10.5194/hessd-12-705-2015
© Author(s) 2015. This work is distributed
under the Creative Commons Attribution 3.0 License.
Research article
16 Jan 2015
Review status
This discussion paper has been under review for the journal Hydrology and Earth System Sciences (HESS). The manuscript was not accepted for further review after discussion.
Inter-annual variability of dissolved inorganic nitrogen in the Biobío River, Central Chile: an analysis base on a decadal database along with 1-D reactive transport modeling
M. Yévenes1, R. Figueroa2, O. Parra2, and L. Farías3 1Centro de Ciencia del Clima y la Resiliencia (CR)2, Laboratorio de Procesos Oceanográficos y clima (PROFC), Universidad de Concepción, Concepción, Chile
2Facultad de Ciencias Ambientales, Centro de Ciencias Ambientales EULA, Universidad de Concepción, Concepción, Chile
3Departamento de Oceanografía, Centro de Ciencia del Clima y la Resiliencia (CR)2, Universidad de Concepción, Concepción, Chile
Abstract. Rivers may act as important sinks (filters) or sources for inorganic nutrients between the land and the sea, depending on the biogeochemical processes and nutrient inputs along the river. This study examines the inter-annual variability of dissolved inorganic nitrogen (DIN) seasonal (wet–dry) cycle for the Biobío River, one of the largest and most industrialized rivers of Central Chile (36°45'–38°49' S and 71°00'–73°20' W). Long-term water flow (1990–2012) and water quality datasets (2004–2012) were used along with a one-dimensional reactive transport ecosystem model to evaluate the effects of water flow and N inputs on seasonal pattern of DIN. From 2004 to 2012, annual average nitrate levels significantly increased from 1.73 ± 2.17 μmol L−1 (upstream of the river) to 18.4 ± 12.7 μmol L−1 (in the river mouth); while the annual average oxygen concentration decreased from 348 ± 22 to 278 ± 42 μmol L−1 between upstream and downstream, indicating an additional oxygen consumption. Variability in the mid-section of the river (station BB8) was identified as a major influence on the inter-annual variability and appeared to be the site of a major anthropogenic disturbance. However, there was also an influence of climate on riverine DIN concentrations; high DIN production occurred during wet years, whereas high consumption proceeded during dry years. Extremely reduced river flow and drought during summer also strongly affected the annual DIN concentration, reducing the DIN production. Additionally, summer storm events during drought periods appeared to cause significant runoff resulting in nitrate inputs to the river. The total DIN input reaching the river mouth was 0.159 Gmol yr−1, implying that internal production exceeds consumption processes, and identifying nitrification as one of the predominant processes occurring in the estuary. In the following, the impact on the river of DIN increases as a nutrient source, as well as climate and biogeochemical factors are discussed.

Citation: Yévenes, M., Figueroa, R., Parra, O., and Farías, L.: Inter-annual variability of dissolved inorganic nitrogen in the Biobío River, Central Chile: an analysis base on a decadal database along with 1-D reactive transport modeling, Hydrol. Earth Syst. Sci. Discuss., 12, 705-738, doi:10.5194/hessd-12-705-2015, 2015.
M. Yévenes et al.
M. Yévenes et al.

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This study examines the inter-annual variability of dissolved inorganic nitrogen (DIN) seasonal cycle for the Biobío River in Central Chile. Historical water flow and water quality datasets were used along with a one-dimensional reactive transport ecosystem model to evaluate the effects of water flow and N inputs on seasonal pattern of DIN. Results showed that high DIN production occurred during wet years, whereas high consumption proceeded during dry years. Nitrification was identified as one o
This study examines the inter-annual variability of dissolved inorganic nitrogen (DIN) seasonal...
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