Chiara Santinelli

Italian National Research Council | CNR · Institute of Biophysics IBF

The measurements of dissolved organic carbon (DOC), nitrogen (DON), and phosphorus (DOP) are used to characterize the dissolved organic matter (DOM) pool and are important components of biogeochemical cycling in the coastal ocean. Here, we present the first edition of a global database (CoastDOM v1; available at https://figshare.com/s/512289eb43c4f...

Fluorescence excitation-emission matrices (EEMs) are a useful tool in aquatic sciences for monitoring and studying the biogeochemistry of organic matter in natural waters and engineered systems. Yet, the interpretation of the wealth of information available in EEMs requires the use of appropriate software. Existing software tools for the analysis o...

In the marine coastal environment, freshwater and seawater coalescing communities are facing a complex set of abiotic and biotic cross-influences. This study aimed at evaluating the respective influences of blending and prokaryotic dynamics on community structure. For that, the surface salinity gradient of a nutrient-rich estuary (Arno River, Medit...

Exudates by the diatom Phaeodactylum tricornutum were incubated with a natural community of marine heterotrophic prokaryotes for 24 d in order to investigate the link between the biological lability and the molecular weight, fluorescence, and polarity of phytoplankton dissolved organic matter (DOM). Dissolved organic carbon (DOC) removal, changes i...

This chapter gives an overview of the general biogeochemistry in the Mediterranean Sea explaining the particularities of the main biogeochemical variables and the physical, biological, and geochemical processes driving their distribution in the main basins of this marginal sea. Each subsection focuses on one essential variable, starting from dissol...

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...

In the dark ocean, the balance between the heterotrophic carbon demand and the supply of sinking carbon through the biological carbon pump remains poorly constrained. In situ tracking of the dynamics of microbial degradation processes occurring on the gravitational sinking particles is still challenging. Our particle sinking simulator system (PASS)...

Marine dissolved organic matter (DOM) contains more carbon than the combined stocks of Earth’s biota. Organisms in the ocean continuously release a myriad of molecules that become food for microheterotrophs, but, for unknown reasons, a residual fraction persists as DOM for millennia. In this Perspective, we discuss and compare two concepts that cou...

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 in...

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 i...

The determination of copper (Cu) speciation and its bioavailability in natural waters is an important issue due to its specific role as an essential micronutrient but also a toxic element at elevated concentrations. Here, we report an improved anodic stripping voltammetry (ASV) method for organic Cu speciation, intended to eliminate the important p...

Most of the ocean is deep with the majority of its volume (> 80%) lying under a depth greater than 1000 m. Deep-ocean substrates input is mainly supplied as organic matter (in particulate and/or dissolved forms) by physical and biological processes. Bioavailable dissolved organic carbon (DOC) is mainly consumed in surface water by prokaryotes, whil...

In the oligotrophic ocean where inorganic phosphate (Pi) concentrations are low, microorganisms supplement their nutrient requirements with phosphorus (P) extracted from dissolved organic matter (DOM). Most P in DOM is bound as phosphate esters, which are hydrolyzed by phosphoesterases to Pi. However, a large fraction of DOM‐P occurs as phosphonate...

The last few decades have seen dramatic changes in the hydrography and biogeochemistry of the Mediterranean Sea. The complex bathymetry and highly variable spatial and temporal scales of atmospheric forcing, convective and ventilation processes contribute to generate complex and unsteady circulation patterns and significant variability in biogeoche...

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 investiga...

Atmospheric fluxes of dissolved organic matter (DOM) were studied for the first time on the island of Lampedusa, a remote site in the central Mediterranean Sea (Med Sea), between 19 March 2015 and 1 April 2017. The main goals of this study were to quantify total atmospheric deposition of DOM in this area and to evaluate the impact of Saharan dust d...

The last decades have seen dramatic changes in the hydrography and biogeochemistry of the Mediterranean Sea. The complex bathymetry, highly variable spatial and temporal scales of atmospheric forcing and internal processes contribute to generate complex and unsteady circulation patterns and significant variability in biogeochemical systems. Part of...

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 contr...

Abstract. Atmospheric fluxes of dissolved organic matter (DOM) were studied for the first time at the Island of Lampedusa, a remote site in the Central Mediterranean Sea (Med Sea), close to the Sahara desert, between 19 March 2015 and 1 April 2017. The main goals of this work are: to quantify total atmospheric deposition of DOM in this area and to...

The study of dissolved organic matter (DOM) in natural waters is hindered by its complex structure and low concentration. Spectroscopic methods (e.g. UV–Vis spectrometry) can be used for the characterization of its chromophoric fraction (CDOM) due to their simplicity, rapid response, low price and high sensitivity. The absorption spectrum of CDOM i...

Southern Adriatic (Eastern Mediterranean Sea) is a region strongly dominated by large-scale oceanographic processes and local open-ocean dense water formation. In this study, picoplankton biomass, distribution, and activity were examined during two oceanographic cruises and analyzed in relation to environmental parameters and hydrographic condition...

The northern Red Sea (NRS) is a low-nutrient, low-chlorophyll (LNLC) ecosystem with high rates of atmospheric deposition due to its proximity to arid regions. Impacts of atmospheric deposition on LNLC ecosystems have been attributed to the chemical constituents of dust, while overlooking bioaerosols. Understanding how these vast areas of the ocean...

In the Mediterranean Sea (Med Sea), Dissolved Organic Matter (DOM) dynamics shows some peculiarities that can be investigated by using its optical properties. Despite being a marginal sea, the Med Sea behaves as a miniature ocean for DOM concentrations and distribution. Its surface waters are “greener” than it would normally result from their gener...

The JRC exploratory project RIMMEL provides information about litter, mainly plastic waste, entering the European Seas through river systems. RIMMEL has collected data on riverine floating macro litter inputs to the sea. Data acquisition was based on the Riverine Litter Observation Network (RiLON) activities, which collected data from rivers in the...

Natural organic matter (NOM) is one of the major components of aquatic ecosystems which controls functioning of ecological processes and biogeochemical cycles. Coloured dissolved organic matter (CDOM), as an important part of the NOM, is responsible for the light absorption. For many estuarine systems, riverine discharge is considered as the main s...

Characterizing carbon cycling and redistribution in the ocean is an important issue for Mankind, because it may affect key ecosystem services, e.g., support to climate system and food provision. In this paper, using an integrated approach, we explore the impact of the surface circulation on carbon dynamics in the Western Mediterranean Sea, where st...

Desert dust storms are frequent in the Northern Red Sea region, providing nutrients (i.e., PO4) and trace-metals (i.e., Fe) that may stimulate dinitrogen (N2) fixation. Dust also carries a high diversity of airborne microbes (bacteria and archaea), including diazotrophs, that may remain viable during transport and upon deposition. Here we evaluate...

Microbial processes involved in water biogeochemistry are linked to physical and chemical variability of water masses. While the occurrence of hydrological changes in the Eastern Mediterranean Sea has been documented, its effects on microbial dynamics and processes have been poorly investigated. An interdisciplinary survey was carried out in Novemb...

To obtain qualitative information on the Black Sea's dissolved organic matter (DOM) pool, the optical properties (absorption and fluorescence) were measured in 111 samples collected across the basin. Chromophoric dissolved organic matter (CDOM) was considered at three wavelengths (254 nm, 280 nm, and 325 nm), along with the spectral slope between 2...

We present concentration and isotopic profiles of total, size, and polarity fractionated dissolved organic carbon (DOC) from Station ALOHA, an oligotrophic site in the North Pacific Ocean. The data show that between the surface and 3500 m, low molecular weight (LMW) hydrophilic DOC, LMW hydrophobic DOC and high molecular weight (HMW) DOC constitute...

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In the deep ocean, fluxes of particulate organic carbon (POC) and calcium carbonate are positively correlated, suggesting that CaCO3 could increase sinking particle densities and/or protect the organic matter from degradation by prokaryotes, the so called “ballast effect”. Here, we used the PArticle Sinking Simulator (PASS) system to investigate th...

Trace metal (TM) concentrations in water samples collected in the Arno River, its main tributaries and estuarine transect were measured in order to evaluate anthropogenic influence, TM dynamics and a potential impact on the coastal sea. A downstream increase of concentration for most of TM was observed in the river, whereas a (near)conservative beh...

Organic matter concentration and the optical properties of its chromophoric fraction (CDOM) were measured along the Arno River and in its estuary, in September 2015. Organic matter concentration strongly increased along the river, while in the estuary it was mainly affected by conservative mixing.

During the SESAME EU FP6 project, all available particulate organic carbon (POC) data collected from drifting sediment trap and Underwater Vision Profiler deployments (INSU PROOF database, 1991-2011) were gathered in order to assess carbon export at the scale of the Mediterranean Sea. In this study, we observed that particle size, POC export, and t...

Dissolved organic carbon (DOC), chromophoric and fluorescent dissolved organic matter (CDOM and FDOM, respectively) surface distribution was studied during the Serious Game exercise carried out in the Eastern Ligurian Sea, where an oil spill was localized by using satellite images and models. This paper reports the first DOC, CDOM and FDOM data for...

This chapter summarizes the present knowledge of dissolved organic carbon (DOC) dynamics in the Mediterranean Sea, highlighting the basin as a natural laboratory for DOC dynamics in the global ocean. After a general description of the main characteristics of the Mediterranean Sea and its thermohaline circulation pattern, the basin-scale DOC distrib...

Estuaries are the primary interface between land and sea where most of the organic carbon undergoes physical, chemical and biological transformation before it enters into the marine environment. Arno river (Tuscany, Italy) has a low discharge (2.6 Km3/y), compared to the main Mediterranean Sea rivers, however it represents an important source of di...

Abstract One of the most intriguing aspects of dissolved organic carbon (DOC) dynamics in the Mediterranean Sea (Med Sea) is that in the intermediate and deep waters, DOC concentrations are equal to the lowest values found in the deep Atlantic and Pacific (36–42 μM). The very low DOC values in the deep Med Sea were unexpected since the renewal time...

PERSEUS project aims to identify the most relevant pressures exerted on the ecosystems of the Southern European Seas (SES), highlighting knowledge and data gaps that endanger the achievement of SES Good Environmental Status (GES) as mandated by the Marine Strategy Framework Directive (MSFD). A complementary approach has been adopted, by a meta-anal...

DOC concentration and CDOM optical properties (absorption and fluorescence) were measured weekly in the Arno river (Italy) during 2014. Despite its low discharge (2.6 Km3/y), compared to the major rivers of the Mediterranean Sea, Arno river represents an important source of DOC and CDOM to the coastal area, due to its high DOC concentration ( ~300...

Significance Oceanic dissolved organic carbon (DOC) contains as much carbon as Earth’s atmosphere, yet its cycling timescales and composition remain poorly constrained. We use serial oxidation experiments to measure the quantitative distribution of carbon isotopes inside the DOC reservoir, allowing us to estimate both its cycling timescales and sou...

Dissolved organic carbon (DOC) and optical properties (absorption and fluorescence) of chromophoric dissolved organic matter (CDOM) were measured in October 2012, at the Arno river mouth and in a coastal station close to it. The data reported indicates that the Arno river represents an important source of DOC and CDOM to this coastal area, with a t...

This study report the first Dissolved Organic Carbon (DOC) and Cromoforic Dissolved Organic Matter (CDOM) data for a large coastal area of the southern Tyrrhenian Sea strongly impacted by river inputs. The input of both DOC and CDOM is well visible at the mouth of all rivers and it is correlated to the river discharge. CDOM optical properties show...

This study reports the first information on extracellular enzymatic activity (EEA) combined with a study of DOM dynamics at the Arno River mouth. DOM dynamics was investigated from both a quantitative (dissolved organic carbon, DOC) and a qualitative (absorption and fluorescence of chromophoric DOM, CDOM) perspective. The data here reported highlig...

The oxidative decoloration of Rhodamine B (RhB) was performed in a photochemical reactor which enables microwave (MW) and UV radiation to be applied simultaneously. We used an immersed microwave source, with no need for an oven. Controlling the temperature, MW power, and UV emission of the reactor all led to a greater overall control of the process...

Total (TOC) and dissolved (DOC) organic carbon vertical profiles were analyzed from 11 stations located in various regions of the Mediterranean Sea, together with the distribution of other physical, chemical and biological parameters. TOC showed the highest concentrations (68-83 μM) above the pycnocline, followed by a marked decrease to values of 4...

To date the contribution of the Mediterranean Sea (MS) to the global carbon budget is still under debate. Due to the extensive coast line and high population density, terrestrial inputs and anthropogenic pressures strongly influence the dissolved organic carbon (DOC) cycle in the MS. There is a great debate about the biophysical processes affecting...

The distribution of extracellular enzymatic activities (EEA) [leucine aminopeptidase (LAP), ß-glucosidase (GLU), alkaline phosphatase (AP)], as well as that of prokaryotic abundance (PA) and biomass (PB), dissolved organic carbon (DOC), particulate organic carbon and particulate total nitrogen (POC, PTN), was determined in the epi-, meso-, and bath...

Seven years (2001–2008) of dissolved organic carbon (DOC) vertical profiles were examined in order to assess the main processes determining DOC concentration and distribution in the meso- and bathypelagic layers of the Mediterranean Sea. As expected, DOC showed high and highly variable concentrations in the surface layer of 57–68 μM (average values...

In this study, we present results on seasonal and spatial changes in CDOM absorption and fluorescence (fCDOM) in a deep mountain lake (Salto Lake, Italy). A novel approach was used to describe the shape of CDOM absorption between 250-700 nm (distribution of the spectral slope, S(lambda)) and a new fluorescence ratio is used to distinguish between h...

The winters 2004/2005 and 2005/2006 were characterised by the formation in the north-western Mediterranean Sea of dense waters, which were significantly warmer and saltier than previously. The temperature-salinity diagrams show the presence of three different deep water types, a resident one and two newly formed ones. In order to quantitatively eva...

Two surveys (March and September 2001), were carried out in the Sardinian Sea in order to investigate dissolved organic carbon (DOC) dynamics in a coastal area affected by intense mesoscale activity. DOC ranged from 38 μM to 94 μM without a clear seasonality, but with marked differences between the two surveys in the processes driving its surface d...

Multivariate statistical techniques are used to demonstrate the fundamental role of CDOM optical properties in the description of water masses during the summer stratification of a deep lake. PC1 was linked with dissolved species and PC2 with suspended particles. In the first principal component that the role of CDOM bio-optical properties give a b...

Vertical profiles of dissolved organic carbon (DOC) in different areas of the Mediterranean Sea were studied during 6 oceanographic surveys conducted between January 1999 and September 2001. The study areas were located at key points of water mass circulation of the entire Mediterranean basin. DOC showed similar behaviors at all hydrological statio...

This paper concerns the current debate as to whether oceans are heterotrophic or autotrophic environments. Microbes are responsible for the assimilation and remineralization of CO2 in the sea and microbial processes are involved in the Earth climatic change. The variability of microbial biomass and activities were studied in the Mediterranean Sea w...

An investigation on the distribution of dissolved organic carbon (DOC) and chromophoric dissolved organic matter (CDOM) in coastal waters of the northern Tyrrhenian Sea, affected by the Arno River discharge, is reported and discussed. Data refer to a survey carried out aboard of the R/V Urania in January 2000. The study period was characterized by...

[1] Dissolved and particulate organic carbon, bacterial biomass, microbial enzymatic activities (EEA: leucine aminopeptidase, beta-glucosidase, and alkaline phosphatase), bacterial production, respiration rates, and bacterial growth efficiency were determined in 10 stations of the Ionian Sea (winter 1998-1999) with the aim of characterizing the rec...

Dissolved organic carbon (DOC) and particulate organic carbon (POC) distribution in the water column were investigated at eight hydrological stations, located in the Ionian Sea, during January 1999. DOC and POC exhibited values in the range 50-73 muM and 0.7-2.7 muM, respectively, in the surface waters, and 31-62 muM and 0.2-0.8 muM in the intermed...

Estuarine and coastal water samples were collected in 61 stations located close to the Arno estuary, in the winter 2000, in order to investigate the role played by the Arno river on the distribution of DOC and CDOM in this area. Contour plots of physical and chemical properties together with contour plots of DOC and CDOM fluorescence (Fn(280) and F...

Vertical profiles of dissolved organic carbon (DOC) from eight hydrological stations in the Tyrrhenian Sea, Sardinia Channel and Algerian Sea, are reported. DOC exhibits concentrations ranging from 58 to 88μM in surface water, 43–57μM in the intermediate layer and 49–63μM in deep waters. The assessment of the hydrological characteristics allows dif...