Effects of nitrate and phosphate supply on chromophoric and fluorescent dissolved organic matter in the Eastern Tropical North Atlantic: a mesocosm study.

Loginova, Alexandra N., Borchard, Corinna, Meyer, Judith, Hauss, Helena , Kiko, Rainer and Engel, Anja (2015) Effects of nitrate and phosphate supply on chromophoric and fluorescent dissolved organic matter in the Eastern Tropical North Atlantic: a mesocosm study. Open Access Biogeosciences (BG), 12 . pp. 6897-6914. DOI 10.5194/bg-12-6897-2015.

[img]
Preview
Text
bg-12-6897-2015.pdf - Published Version
Available under License Creative Commons: Attribution 3.0.

Download (1802Kb) | Preview
[img]
Preview
Text
bg-12-6897-2015-supplement.pdf - Supplemental Material
Available under License Creative Commons: Attribution 3.0.

Download (978Kb) | Preview

Supplementary data:

Abstract

In open-ocean regions, as is the Eastern Tropical North Atlantic (ETNA), pelagic production is the main source of dissolved organic matter (DOM) and is affected by dissolved inorganic nitrogen (DIN) and phosphorus (DIP) concentrations. Changes in pelagic production under nutrient amendments were shown to also modify DOM quantity and quality. However, little information is available about the effects of nutrient variability on chromophoric (CDOM) and fluorescent (FDOM) DOM dynamics. Here we present results from two mesocosm experiments ("Varied P" and "Varied N") conducted with a natural plankton community from the ETNA, where the effects of DIP and DIN supply on DOM optical properties were studied. CDOM accumulated proportionally to phytoplankton biomass during the experiments. Spectral slope (S) decreased over time indicating accumulation of high molecular weight DOM. In Varied N, an additional CDOM portion, as a result of bacterial DOM reworking, was determined. It increased the CDOM fraction in DOC proportionally to the supplied DIN. The humic-like FDOM component (Comp.1) was produced by bacteria proportionally to DIN supply. The protein-like FDOM component (Comp.2) was released irrespectively to phytoplankton or bacterial biomass, but depended on DIP and DIN concentrations. Under high DIN supply, Comp.2 was removed by bacterial reworking, leading to an accumulation of humic-like Comp.1. No influence of nutrient availability on amino acid-like FDOM component in peptide form (Comp.3) was observed. Comp.3 potentially acted as an intermediate product during formation or degradation of Comp.2. Our findings suggest that changes in nutrient concentrations may lead to substantial responses in the quantity and quality of optically active DOM and, therefore, might bias results of the applied in situ optical techniques for an estimation of DOC concentrations in open-ocean regions.

Document Type: Article
Research affiliation: OceanRep > SFB 754 > B2
OceanRep > SFB 754
OceanRep > SFB 754 > B8
OceanRep > GEOMAR > FB3 Marine Ecology > FB3-EOE-N Experimental Ecology - Food Webs
OceanRep > GEOMAR > FB2 Marine Biogeochemistry > FB2-BI Biological Oceanography
OceanRep > GEOMAR > FB3 Marine Ecology > FB3-EOE-B Experimental Ecology - Benthic Ecology
OceanRep > SFB 754 > B9
Refereed: Yes
Open Access Journal?: Yes
DOI etc.: 10.5194/bg-12-6897-2015
ISSN: 1726-4170
Related URLs:
Projects: SFB754
Expeditions/Models/Experiments:
Date Deposited: 22 May 2015 07:47
Last Modified: 11 Dec 2018 10:03
URI: http://oceanrep.geomar.de/id/eprint/28809

Actions (login required)

View Item View Item

Document Downloads

More statistics for this item...