About the lab

La!DOM, a research group at the Institute of Biophysics (CNR), was the first group in Italy to develop the method for the treatment of samples and the analysis of the concentration of DOC in seawater. Since 2000, we have collected more than 10000 samples from all over the Mediterranean Sea.

Our research activities:
- Role of the Mediterranean Sea in the global carbon cycle
- DOM biological lability
- DOM dynamics in rivers
- Atmospheric deposition of DOM
- Optical properties (absorption and fluorescence) of CDOM
- Use of fluorescence as an indicator of organic contamination
- Extracellular enzimatic activity
- DOM release from bioplastics
- DOM dynamics during COVID-19 pandemic

Visit our website https://www.ladom.it/en/

Featured research (9)

The fast spread of SARS-CoV-2 virus in Italy resulted in a 3-months lockdown of the entire country. During this period, the effect of the relieved anthropogenic activities on the environment was plainly clear all over the country. Herein, we provide the first evidence of the lockdown effects on riverine dissolved organic matter (DOM) dynamics. The strong reduction in anthropogenic activities resulted in a marked decrease in dissolved organic carbon (DOC) concentration in the Arno River (−44%) and the coastal area affected by its input (−15%), compared to previous conditions. The DOM optical properties (absorption and fluorescence) showed a change in its quality, with a shift toward smaller and less aromatic molecules during the lockdown. The reduced human activity and the consequent change in DOM dynamics affected the abundance and annual dynamics of heterotrophic prokaryotes. The results of this study highlight the extent to which DOM dynamics in small rivers is affected by secondary and tertiary human activities as well as the quite short time scales to return to the impacted conditions. Our work also supports the importance of long-term research to disentangle the effects of casual events from the natural variability.
Lateral advection affects the spatial distribution of dissolved substances in the ocean but very few studies, so far, have been devoted to describe and quantify its impact on the distribution of dissolved organic carbon (DOC) which, in oligotrophic environments, accounts for the largest fraction of chemical energy. In this contribution, using an integrated approach, we explore the importance of surface advection on carbon dynamics in the Western Mediterranean Sea, where strong inter-basin differences in primary production do exist. Detailed information on the surface circulation, derived from high-resolution model simulations, is combined with the analysis of spatially resolved, accurate DOC vertical profiles, repeated over time. Our data show that surface circulation plays a crucial role in regulating DOC concentrations and distributions in the Tyrrhenian Sea and that horizontal transport of DOC into the Tyrrhenian Sea is of the same order of magnitude as in-situ DOC production. Our study addresses this process for the first time in the Mediterranean Sea, whose small size allows for fast, inter-basin transfer times which, in turn, favors the preservation of the DOC stock produced elsewhere. We highlight that this mechanism may be important also in other regions of the oceans, where surface advection may set up a sort of compensation among regions with different trophic regimes, thus smoothing trophic gradients. We posit that understanding these transport processes is a crucial and preliminary step to understand and quantify all the other processes (biological, chemical, geological) that influence DOC distribution on a variety of timescales.
Estuarine processes play a key role in determining the amount and quality of land-derived dissolved organic matter (DOM) reaching the oceans. Microbial-mediated reactions can affect the concentration, quality, and bioavailability of DOM within an estuary. In this study, we investigated biological DOM removal in a small estuary and its variability in two contrasting seasons (spring and autumn) characterized by natural differences in the concentration and quality of the riverine DOM. Two incubation experiments were carried out using natural DOM and heterotrophic prokaryotes community collected at the estuary in March and September. Dissolved organic carbon (DOC) concentration, DOM fluorescence, and the heterotrophic prokaryotes abundance (HPA) showed marked differences between the two seasons. These parameters were followed through time for up to two months. Despite the marked differences in the initial conditions, the DOC removal rates were surprisingly similar in the two periods (16 µM DOC month −1 in March and 18 µM DOC month −1 in September), with the biggest removal in the first 48 h. The trend of fluorescent DOM (FDOM) during the incubation showed marked differences between the two periods. In March, the net removal of all the FDOM components was observed consistently with the decrease in DOC; whereas, in September, the net production of humic-like substances was observed.
Photodegradation is a natural process that strongly affects the chromophoric fraction of dissolved organic matter (DOM), especially in surface water of the oceans. In the euphotic zone, the concentration and quality of DOM are mostly dependent on primary production by phytoplankton. The effect of photodegradation on algal DOM has not been investigated as much as on terrestrial DOM. In this study, we explored the effect of different spectral regions (i.e., full sun spectrum, visible light, 295-800 nm, 305-800 nm, and 320-800 nm) on algal exudates by Emiliania huxleyi, a ubiquitous coccolithophore. The optical properties (absorption and fluorescence) of algal DOM were investigated before and after irradiation with the different spectral regions. The absorption and fluorescence spectra were compared before and after irradiation. The results showed an increase in the effect of photobleaching with increasing irradiation energy for all of the absorbance indices. Similarly, the protein-like fluorescence decreased at increasing irradiation energy. The humic-like fluorescence, which was the most affected, did not show a linear trend between photobleaching and irradiation energy, which suggested that irradiation mainly determined a change in these molecules' quantum yield.
In this study, dissolved organic carbon (DOC) data and optical properties (absorbance and fluorescence) of DOM, weekly collected in the Arno River for 2 years, are used to investigate the main processes determining DOM temporal dynamics in a small Mediterranean river, with torrential hydrology and medium-high human impact, and to quantify the contribution of this river to Med Sea carbon budget. A clear seasonal cycle of DOM, with DOC values ranging between 170 and 490 μM, was observed. Optical properties indicates that DOM quality in the river is different depending on the season; terrestrial humic-like substances prevail in winter, when discharge and floods are the main drivers of DOM concentration and quality, whereas autochthonous protein-like substances prevail in spring and summer, when biological processes dominate. Our results provide a robust estimate of the DOC flux to the Med Sea (9.6 · 10⁹ g DOC yr⁻¹) and of its range of variability (12.95 · 10⁹–5.12 · 10⁹ g DOC yr⁻¹). The 80% of this flux was generally delivered during autumn/winter with significant amounts ascribed to single flood events (up to 26% in 2014). This study, by providing a rich dataset on water quantity and quality and by quantifying the importance of the hydrological regime on DOC transport, represents an important step toward a quantitative modeling of the Arno River.

Lab head

Chiara Santinelli
Department
  • Institute of Biophysics IBF

Members (5)

Margherita Gonnelli
  • Italian National Research Council
Stefano Vestri
  • Italian National Research Council
Simona Retelletti Brogi
  • Italian National Research Council
Giancarlo Bachi
  • Università di Pisa
Valtere Evangelista
  • Italian National Research Council
Yuri Galletti
Yuri Galletti
  • Not confirmed yet
Giovanni Checcucci
Giovanni Checcucci
  • Not confirmed yet