Effects of recirculation of seawater enriched in inorganic nitrogen on dissolved organic carbon processing in sandy seepage face sediments

Abstract

Please cite this article as: Ibánhez, J. Severino P., Rocha, Carlos, Effects of recirculation of seawater enriched in inorganic nitrogen on dissolved organic carbon processing in sandy seepage face sediments, Marine Chemistry (2014Chemistry ( ), doi: 10.1016Chemistry ( /j.marchem.2014 This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain. suggest that the availability of DIN in permeable seepage faces increases the net production of labile DOC, by enhancing the ability of the benthic microbial community to process refractory organic matter. Hence, we suggest that increasing DIN availability in coastal permeable sediments accelerates benthic organic C processing, promoting the release of more labile DOC to receiving water bodies.

Oxygen transport and reactivity within a sandy seepage face in a mesotidal lagoon (Ria Formosa, Southwestern Iberia)

“…Relevant sediment properties during the field sampling campaigns performed during December 2009 and April 2010 showed high similarity to those presented in Rocha et al () and Ibánhez and Rocha () for previous work at the site (including those reported for October 2010 and January 2011 when the experimental work presented here was performed). Sediment porosity at the seepage face (Stations A and B) was characterized by low temporal variability (Supporting Information Fig.…”

“…Those findings together with the vertical distribution of aerobic respiration rates and the absence of substantial seasonal difference among both experimental periods suggest that at the highest imposed seepage rates and under O 2 saturated porewater, aerobic heterotrophic processes are ultimately constrained by OM availability and quality at the seepage face. Low standing stocks of OM within the sediment (Rocha et al ; Ibánhez and Rocha ; Supporting Information Fig. 1) together with the measured aerobic respiration rates suggest the fast turnover of OM within the seepage face sediment.…”

“…FTR experiments aiming to elucidate the dynamics of benthic aerobic respiration were run in triplicate with sediment and porewater collected in situ at the peak of the discharge within the seepage face (Station A) during October 2010 and January 2011. A complete description of the FTR experiments can be found in Ibánhez and Rocha (). There, the reactivity of the dissolved organic matter at the seepage face was explored in a series of FTR experiments, which included those used here during January 2011.…”

“…Thus, the magnitude and dynamics of interfacial water transport coupled to the benthic metabolism in place determine the oxygenation levels of beach groundwater (Anschutz et al ; Charbonnier et al ). As a consequence, tidal sands can act as biogeochemical reactors and actively mediate the transfer of elements between land and the coastal ocean, thus contributing to the turnover of C, O, N, or P, among others, in the coastal zone (Moore ; de Beer et al ; Anschutz et al ; Rocha et al ; Ibánhez et al ; Ibánhez and Rocha ). However, little information is available on how coupling between porewater advection and benthic metabolism might result in strong O 2 porewater gradients across which oxic and suboxic/anoxic biogeochemical processes may occur in close proximity.…”

Does Nitrate Enrichment Accelerate Organic Matter Turnover in Subterranean Estuaries?

“…Due to the high mobility of N compounds in the environment and the role N plays in microbial and primary producer metabolism, anthropogenic N enrichment of STEs could also promote alterations on the cycling of other elements such as C. Hence, mobilization of organic C from high residence time reservoirs like peat bogs (Bragazza et al, 2006), the Artic tundra (Mack et al, 2004), or alpine steppes (Chen et al, 2020) is increasingly linked to the enhancement of microbial and enzymatic activity caused by anthropogenic N enrichment. Nevertheless, to our knowledge, the effect of N enrichment on the transformation of organic matter in STEs has only been explored to date in incubation experiments (Ibánhez and Rocha, 2014a). In this study, we use an extensive field dataset collected in an STE seepage face to explore the effects of changing N enrichment within the STE over the quantity and quality of the fluorescent dissolved organic matter (FDOM).…”