lettre wp3n°2

MERMEX – WP3
C 3A
C O PEL
RIV E RS
C ASC ADE
C O BEC
SG D
La Lettre – 2
Edito
O.Radakovitch, C.Rabouille
It has been a year since our last WP3 newsletter, and a large research effort on the “Land-­‐Ocean interaction including extreme events” has been going on since then. In this letter, we present the results from two ongoing projects: CASCADE and C3A. The main cruise of CASCADE (Cascading, Storm, Convection, Advection, and Downwelling Events) was conducted 2 years ago on the RV Atalante. It followed the formation of dense water over the year 2012 in the Gulf of Lion, trying to disentangle the processes driving this phenomenom. The action C3A (Contaminant inputs from large Cities in the Coastal Area) studies the fate of contaminants and its consequence for ecosystems around two large cities in the French Mediterranean coast: Marseille and Toulon. The ongoing effort on other programs (COBEC, RIVERS, and SGD) has also continued with an unprecedented intensity. WP3 has also contributed to the international side of MERMEX, hence this editorial in English. MERMEX is now an affiliated project of LOICZ (Land-­‐Ocean Interaction in the Coastal Zone, www.loicz.org), related more especially to the priority topic “Assess and predict impact of environmental change on coastal ecosystems ». Mermex scientists have also developed their international collaborations. Hence, numerous research topics related to coastal processes were discussed during the international MERMEX meeting in Zagreb (June 2013); a research program was started in Tunisia on the contamination of sediments and the response of bacteria and some starting links were made with Algerian, Moroccan Croatian, Italian and Lebanon colleagues. We have no doubt that year 2014 will show even more success of our research programs. The research at the land-­‐ocean interface is a long-­‐term task, especially when extreme events are sought, and long-­‐term observation is definitely needed. Year 2014 will also be the one where a large integrated research effort will be proposed for WP3, and a meeting on the 8th October 2013 will be the time to discuss such an integration. This letter is available through the Mermex Website : http://mermex.pytheas.univ-­‐amu.fr/ 1 Letter WP3 n°2 – September 2013
WP3 Structure
The WP3 of the Mermex program focuses on processes acting at the continent-­‐ocean interface, including extreme events. It is coordinated by O. Radakovitch and C. Rabouille and structured around 6 actions with their own responsibles: • Action 1 -­‐ RIVERS: Influence of extreme events on river delivery of particulate organic carbon, nutrient and contaminants, their fate in the delta and continental shelf and their impact on ecosystems (C. Rabouille) • Action 2 -­‐CASCADE: Cascading, Storm, Convection, Advection, and Downwelling Events (X. Durrieu de Madron) • Action 3 and 4-­‐ COPEL and COBEC : Characterize and model transfers and impacts of contaminants through the marine Benthic (COBEC) and Pelagic (COPEL) food web (J.Tronczynski, O. Pringault et O. Radakovitch) • Action 5 -­‐ C3A : Contaminant inputs from large Cities in the Coastal Area (C. Garnier et I. Pairaud) • Action 6 -­‐ SGD : Characterize and quantify the influence of submarine groundwater discharge (SGD) on marine ecosystems (C. Claude) Cascade
X. Durrieu de Madron
Contributors : L. Houpert, P. Puig, A. Sanchez-­‐Vidal, P. Testor, A. Bosse, C. Estournel, S. Somot, F. Bourrin, M.N Bouin, M. Beauverger, L. Beguery, A. Calafat, M. Canals, L. Coppola, D. Dausse, F. D’Ortenzio, J. Font-­‐, S. Heussner, S. Kunesch, H. Le Goff, J. Martín, L. Mortier, A. Palanques, P. Raimbault Dans le golfe du Lion, la convection en mer ouverte est le mécanisme principal pour le renouvellement des eaux profondes de Méditerranée occidentale. Cependant, la présence épisodique d’anomalies thermo-­‐
halines près du fond suggère une contribution des eaux denses formées sur le plateau continental, avec une récurrence subdécennale. De nouvelles observations acquises pendant l’hiver et l’été 2012 ont permis de mettre en évidence l'interaction de ces processus et confirmer leur rôle dans les caractéristiques des eaux profondes. Récurrence depuis 1970 de l’apparition d’anomalies thermo-­‐halines de fond dans le bassin nord-­‐occidental (adapté de Béthoux et al., 2002) 2 Letter WP3 n°2 – September 2013
Le régime atmosphérique de type « dorsale atlantique » prédominait lors de l'hiver 2012. Ce régime, caractérisé par une anomalie anticyclonique sur l'Atlantique Nord et une anomalie cyclonique sur la mer Baltique, est particulièrement favorable à l’occurrence de vents du nord forts, froids et secs dans le golfe du Lion qui intensifient les pertes de chaleur entre la mer et l’atmosphère. La plupart des hivers avec d’importantes anomalies positives du nombre de jours du régime « dorsale atlantique » correspondent aux années où des anomalies thermo-­‐halines impliquant une formation d’eau profonde d’origine côtière et de mer ouverte ont été observées dans le bassin. Champs de hauteur geopotentielle à 500 hPa pour le régime de dorsale atlantique. Six lignes de mouillage déployées entre 1000m et 2500m de profondeur, et deux bouées de surface sur le plateau et dans le bassin constituaient le réseau d’observation. Ces mouillages sont gérés par le CEFREM et Météo-­‐France dans le cadre du système d’observation MOOSE, ainsi que l’ICM-­‐CSIC et l’UB de Barcelone. Position des lignes de mouillage (PLC, LDC, CCC, HC, FOFA) et bouées (MF-­‐LION, POEM) et carte de la chlorophylle de surface le 22 février 2012 indiquant l’étendue de la zone de convection au large. La zone de formation d’eau dense côtière est délimitée par les eaux de température inférieures à 11°C sur le plateau. La trace en V correspond à la température à 450 m de profondeur mesurée par un glider en février. 3 Letter WP3 n°2 – September 2013
Des eaux particulièrement froides et denses formées sur le plateau en début d’hiver 2012 ont été exportées pendant le mois de février 2012 vers la pente continentale profonde (> 2000 m) en cascadant essentiellement par les canyons du Lacaze-­‐Duthiers et du Cap de Creus. En même temps, la formation d’eau dense était également très active dans le bassin, où la convection atteint le fond en février 2012. Dès mars, cette eau nouvellement formée est soulevée par une intrusion d’une couche d’eau de fond plus froide, moins salée et plus dense, ayant pour origine les eaux denses côtières. À partir des observations, le taux de production d'eau dense (moyennée sur une année) formée par convection en mer ouverte a été estimé (~ 1.1x106 m3s-­‐1). Il est environ un ordre de grandeur supérieur au flux d’eau dense côtière exportée au-­‐delà de 1000 m de profondeur (~ 0.07 x106 m3s-­‐1) Séries temporelles des flux de chaleur et de température au niveau du plateau et du basin, de température de fond dans les canyons (PLC, LDC, CCC) et sur la pente profonde (HC, FOFA), et dans la zone de convection (LION) Quelques mois après, l’intrusion des eaux denses d'origine côtière a créé une couche de fond épaisse de quelques centaines de mètres dans la partie centrale du bassin de la Méditerranée NW. Cette couche de fond est recouverte par une couche d'eau profonde nouvellement formée par la convection en mer ouverte. Les deux couches modifient sensiblement les caractéristiques thermo-­‐halines du bassin profond, contribuant ainsi à amplifier la WMT (Western Mediterranean Transition) initiée en 2005. 4 Letter WP3 n°2 – September 2013
Carte de l’épaisseur de l’anomalie thermo-­‐haline (en rouge sur le diagramme q-­‐S, avec une anomalie de densité potentielle > 29.125 kg m-­‐3) observée pendant le campagne MOOSE en juillet-­‐août 2012. Ces observations ont permis de valider les hypothèses d’interaction dans le bassin profond du Golfe du Lion entre ces deux processus de formation d’eau dense qui avait été conjecturé dès 1999 (Béthoux et al, 2002), puis en 2005 (Canals et al., 2006). Le phénomène de cascade d’eaux dense côtière et son interaction avec la convection en mer ouverte sont susceptibles d’avoir des conséquences importantes sur le transport de matière particulaire et dissoute et sur le fonctionnement des écosystèmes profonds, ainsi que le suggèrent les études récentes de Puig et al. (2013) sur les couches néphéloides profondes et de Tamburini et al (2013) sur la bioluminescence profonde. References • Béthoux J.P., X. Durrieu de Madron, F. Nyffeler & D. Taillez (2002). Deep water in the western Mediterranean: peculiar 1999 and 2000 characteristics, shelf formation hypothesis, variability since 1970 and geochemical inferences. Journal of Marine Systems, 33-­‐34, 117-­‐131 • Canals M., P. Puig, X. Durrieu de Madron, S. Heussner, A. Palanques, J. Fabrès (2006). Flushing submarine canyons. Nature, 444, 354-­‐357. • Durrieu de Madron X., L. Houpert, P. Puig, A. Sanchez-­‐Vidal, P. Testor, A. Bosse, C. Estournel, S. Somot, F. Bourrin, M.N Bouin , M. Beauverger, L. Beguery, A. Calafat, M. Canals, L. Coppola, D. Dausse, F. D'Ortenzio, J. Font, S. Heussner, S. Kunesch, D. Lefevre, H. Le Goff, J. Martín , L. Mortier, A. Palanques, P. Raimbault (2013) Interaction of dense dense shelf water cascading and open-­‐sea convection in the Northwestern Mediterranean during winter 2012. Geophysical Research Letters, 40, 1379-­‐1385, doi:10.1002/grl.50331. • Puig. P., X. Durrieu de Madron, J. Salat; K. Schroeder, J. Martín, A.P Karageorgis, A.Palanques, F. Roullier, J.L Lopez-­‐Jurado, M. Emelianov; T. Moutin, L. Houpert (2013) Thick bottom nepheloid layers in the western Mediterranean generated by deep dense shelf water cascading. Progress in Oceanography, 111, 1-­‐23 • Tamburini C, M. Canals M, X. Durrieu de Madron, L. Houpert, D. Lefèvre, et al. (2013) Deep-­‐sea bioluminescence blooms after dense water formation at the ocean surface. PLoS ONE 8(7): e67523. doi:10.1371/journal.pone.0067523 5 Letter WP3 n°2 – September 2013
C3A
C. Garnier
Contributors : C. Brach-­‐Papa, D. Cossa, D.H. Dang, M. Goutx, B. Oursel, I. Pairaud, C. Pinazo, J. Schäfer, M. Tedetti, B. Thouvenin Large coastal cities are among the most worrying sources of marine pollution, especially in the Mediterranean Sea. A typical example is Marseille, the largest Mediterranean French city, with over 1.7 million inhabitants. Two small rivers, the Huveaune and the Jarret, run through the agglomeration and join before their outlet to the sea. The uniqueness of this system is that the river waters are mixed with the city waste water treatment plants (WWTP) effluents and then rapidly discharged into the open sea without passing through an estuary, so that the WWTPs’ contribution to the water characteristics at the outlet is most likely predominant during baseflow periods. These inputs have a certain impact on the local coastal ecosystem, however, a high number of such anthropized sources along the coast is likely to impact the Contribution to the coastal input (%)
whole Mediterranean Sea. 0
25
50
75
100
Concerning inorganic pollutants, numerous sampling Bi
campaigns (2010 to 2012) were conducted during dry and Cd
wet periods, under contrasting conditions with regard to Ag
river
NO2season, wind and waves (Oursel et al., 2013). One of these Sn
WWTP
Pb
campaigns was performed during an abnormal event, PO43characterized by very high DOC and metal concentrations, NH4+
K+
probably due to the WWTP dysfunction. Water samples Fe
DOC
were systematically collected in rivers, effluents and along ClRb
the salinity gradient to cover the whole freshwater/ Na+
seawater mixing zone. Collected samples were then Cu
Mn
treated and analyzed for DOC/DIC/POC, POC
Zn
dissolved/particulate major/minor/trace elements. In Cs
order to better understand the mechanisms that operate Al
Cr
in the salinity gradient, remobilization experiments were Ti
Co
performed in lab to simulate the outlet effluent/seawater Ni
mixing. NO3As
During baseflow conditions, dissolved and total organic Tl
V
carbon and metal concentrations in the rivers considered Sb
Fwere comparable to values observed for other small Li
coastal Mediterranean rivers, surpassing the world SO42DIC
average river values. Concerning the trace metal dynamics Ca2+
Mo
in the plume salinity gradient, Cu, Cd, Co, Pb and Zn are Be
desorbed from the SPM, increasing the potentially Mg2+
U
bioavailable fraction of these metals. It was clearly Sr
Ba
demonstrated that the release of metal ions can occur at low salinity with fast kinetics followed by partial re-­‐
Figure 1: Contribution of river vs. WWTP at the
adsorption onto SPM; a behavior especially observed for outlet. The dotted line represents equal contribution
of rivers and WWTP (adapted from Oursel et al.,
Cu. Other metals (e.g. Ni) can undergo a fast adsorption 2013).
onto SPM followed by slower desorption. Such unusual behaviors make mandatory the practice of filtration immediately after sampling to avoid under-­‐ or over-­‐estimation of dissolved metal concentrations. A second important point of this study is that, at the outlet, the river signatures were hidden by the WWTP anthropogenic input for most elements or compounds. Indeed, such anthropogenic input was higher than 80% of the total input to the sea for most of the studied inorganic pollutants (dissolved + particulate) or nutrient (dissolved) (Fig. 1). The daily variation of these inputs followed the fluctuations of the TWW issued from WWTP. Although most likely not frequent, the observed abnormal event linked to a WWTP 6 Letter WP3 n°2 – September 2013
malfunction or bypass can temporally strongly enhance the impact of an urbanized area on the coastal zone. Similar phenomena all around the Mediterranean are more than probable, especially in countries without wastewater treatment plants. This underlines the need for such treatment facilities for an improvement of local coastal water quality, but most likely also at a more global scale. Such chronic fluxes of pollutants require better study in comparison to other main sources (large rivers, aerosols, etc.). During wet conditions, trace metals fluxes increased, with a main contribution from rivers (compared to WWTP). Through the adaptation of an original instrumental laboratory device to separate particles accordingly to their settling velocity in seawater followed by the analysis of the elemental (minor, major and trace) content of each particle size fraction, it has been shown that if a main fraction of particulate pollutants settled rapidly in the coastal zone, increasing the pollution status of surface sediments, a non-­‐
negligible fraction remained at the surface of the water column, thereafter exported offshore (Oursel et al., submitted). Considering the high anthropogenic organic matter and trace element contents of the output to the sea, a detailed study of their chemical speciations, which are known to be strongly influenced by dissolved organic ligands, must be performed to evaluate their bioavailability for marine biota. Several campaigns were also performed (2008 to 2012) during dry and wet periods to assess the composition and the spatio-­‐temporal variability of organic pollutants (hydrocarbons) and of fluorescent dissolved organic matter (FDOM) in the vicinity of the Marseille sewage effluent outlet. Subsurface water (SSW) and surface micro-­‐layer water (SML) were collected along a coast–open sea transect. In addition, in situ measurements of temperature, salinity, turbidity, chlorophyll a and FDOM were carried out using a CTD profiler equipped with optical sensors. At the sewage outlet under dry weather conditions, the concentrations in dissolved aliphatic hydrocarbons (AHs) in the SSW and SML ranged from 0.15 to 0.26 µg l-­‐1 and from 0.32 to 0.63 µg l-­‐1, respectively in summer 2009 and winter 2010, with enrichment factors (EFs) varying from 1.9 to 4.2. The concentrations in particulate AHs ranged from 0.05 to 1.4 µg l-­‐1 in the SSW and from 1.4 to 6.4 µg l-­‐1 in the SML, with EFs varying from 4.2 (winter) up to 128 (summer). The AH molecular distributions were very similar in the dissolved and particulate phases, with C16–C23/R ratio ranging from 0.26 to 0.46, indicating the predominance of heavy n-­‐alkanes. UCM was present in the SML in both phases. After heavy rains, particulate AHs in the SSW displayed significant changes in terms of composition (appearance of UCM) and concentration (increase by a factor 4–28), while dissolved samples were little affected (Guigue et al., 2011). For dissolved and particulate phases, the concentrations in polycyclic aromatic hydrocarbons-­‐parents (PAHs-­‐P) in the SSW ranged from 5.7 to 12 ng l-­‐1 and from 4.7 to 21 ng l-­‐1, respectively, while the concentrations in the SML ranged from 127 to 176 ng l-­‐1 (EF = 15–17) and from 6.4 to 137 ng l-­‐1 (EF = 0.7–
29), respectively. The PAHs-­‐P molecular distributions were characterized by rather heavy compounds with a majority of LMW/HMW values < 1. Moreover, according to what was observed for AHs, the heavy rain event impacted mainly the particulate phase with an increase in PAHs-­‐P concentrations by a factor 2–4 (Guigue et al., 2011). FDOM of discrete water samples was investigated using fluorescence excitation-­‐emission matrices (EEMs) combined with parallel factor analysis (PARAFAC). From the sewage effluent outlet to the central Bay of Marseille, a gradient appeared with decreasing FDOM intensities, decreasing DOC, nutrients and faecal bacteria concentrations and increasing salinity values. This gradient was associated with decreasing abundances in protein-­‐like fluorophores and rising abundances in humic-­‐like materials. This shift in FDOM composition illustrated the decrease in wastewater inputs and the increase in marine sources of DOM along the transect. Under dry conditions, FDOM data showed that the sewage effluent spread up to 1300 m off the outlet, but it did not reach the central Bay. Tryptophan-­‐like material was the dominant fluorophore in the sewage effluent and displayed the highest correlations with biogeochemical parameters (organic carbon, phosphates, faecal bacteria). Therefore, we proposed to use its fluorescence intensity to detect and track sewage effluents inputs in the Marseilles coastal marine waters (Tedetti et al., 2012). In situ FDOM measurements performed with the EnviroFlu-­‐HC TRIOS sensor also confirmed that the impact of the sewage effluent remains detectable from its tryptophan signature at least up to 850 m from the discharge point, during periods of low wind (Tedetti et al., 2010). 7 Letter WP3 n°2 – September 2013
More recently in 2013, the MIO built up a new prototype of “Mini-­‐Fluo” submersible fluorometer able of measuring simultaneously phenanthrene and tryptophan-­‐like fluorophores at the µg l-­‐1 (detection limits: 0.1 and 0.4 µg l-­‐1, respectively). This sensor deployed along the Cortiou sewage outlet – marine station transect at Cortiou site. Results show again an extent (circa 1300 m) of the effluent signatures on the Cortiou marine sites together with inputs likely occurring from sediment resuspension (Fig. 2). These results stress the high spatio-­‐temporal variability of urban wastes inputs and the importance of continuously monitoring concentrations of organic contaminants for better evaluating their impact in urban coastal marine areas. Figure 2: Distribution of salinity (S), turbidity, chlorophyll a (Chla), humic C-­‐like fluorophore (Humic C), tryptophan-­‐like fluorophore (TRY) and phenanthrene-­‐like fluorophore (PHE) along the Cortiou transect (from the sewage effluent outlet to open sea) in the Southern Bay of Marseille. In situ measurements were performed in July 2013 under dry weather conditions using a CTD profiler equipped with optical sensors. PHE and TRY were measured with the MiniFluo fluorometer developed at MIO. Tedetti et al. (2013). In order to improve our knowledge of the fate of chemical contaminants issued from large cities and the marine ecosystem's response to the anthropogenic supplies (from rivers, sewage outflows), a modelling strategy of the Bay of Marseille was developed. A hydrodynamic model MARS3D (Pairaud et al., 2011), coupled with a sedimentary model (Verney et al., 2013), a biogeochemical model (Fraysse et al., 2013) and a model of chemical contamination were used. In this paper, we focus on the MASSILIA project, whose goal was to underline how the physical forcing decreases or increases the anthropogenic impact on the coastal ecosystem and the assessment of the chemical contaminant (PCB) inputs (from city to sea) and exports (from mid-­‐sea to open sea). 8 Letter WP3 n°2 – September 2013
The coastal area off Marseille is characterized by numerous physical and biogeochemical forcing. The physical forcing are: wind induced upwelling and downwelling, eddies, intrusion of the Northern Current on the shelf, wind vertical mixing or stratification by heat fluxes. The biogeochemical inputs come from the Rhone River plume, the urban rivers in case of rainfall, the Waste Water Treatment Plant (WWTP), the seabed sediments, the atmosphere and the biogeochemical characteristics of large-­‐scale waters surrounding the Marseille area. The numerical tools and in-­‐situ observations were used in the area off Marseille to answer the following questions: i) What are the respective contributions of the physical forcing in the modulation of the oligotrophic level of this coastal ecosystem submitted to strong anthropogenic supplies? ii) What is the influence of extreme events, which frequency increases with global warming (floods, storms, heat events), on the changes in the first trophic level (phytoplankton) in the Bay of Marseille? iii) Are the chemical contaminant (PCB) inputs from the city to the sea off Marseille, stocked inside the coastal marine area or exported to the open sea? The approach was to study realistic typical and extreme events observed during the years 2007 and 2008. Mistral wind events induced two spots of upwelling (centered at the "Côte Bleue" and off "Cassis") with strong upwards vertical velocity (maximum of 5 cm.s-­‐1 during an upwelling event in November 2008) (Pairaud et al., 2011). The area impacted by ascent of deep water was characterized by low temperature and high nutrient concentrations. These nutrient concentrations induced an increase in chlorophyll-­‐a concentrations in the upwelling spot and at the front between the upwelled water and the Rhone River plume water. In addition, sediment erosion occurred in the south part of the Bay of Marseille, where the fetch for Mistral wind was the larger. The suspended particulate matter and the adsorbed chemical contaminant (PCB) were mostly exported offshore by currents. South-­‐Easterly wind events induced strong intrusion of large-­‐scale waters inside the domain and a downwelling at the coast, inducing a vertical homogenization of the water column. This wind was associated with waves, which induced sediment erosion near the WWTP outlets, especially during storms. The suspended particulate matter and the adsorbed chemical contaminant (PCB) were transported nearshore or alongshore by currents in the Calanques area. The end of summer rainfall had a weak impact on hydrodynamics, but induced significant nutrients, suspended matter and PCB inputs (Figure 3) in the Bay of Marseille by urban rivers and by the WWTP. The nutrients did not promote a significant phytoplankton production, which was limited by light and temperature in fall. The intrusion event of Rhone Marseille
River diluted water in the Bay of Marseille induced a decrease in salinity and an increase in nutrients, suspended matter and PCB concentrations. The nutrient enrichment induced a phytoplankton production and an increase in chlorophyll-­‐a concentrations, potentially associated with PCB biosorption. These events ©B. Thouvenin, Ifremer
could be associated with an anticyclonic eddy located off Figure 3: Percentile 95 of total (dissolved and particulate) CB153 at the surface during
the Rhone River mouth (Fraysse a 8-day period of strong rainfall events in december 2008 (B. Thouvenin, Ifremer) et al., 2013). 9 Letter WP3 n°2 – September 2013
Depth (cm)
Depth (cm)
Toulon: Toulon bay is divided in two non-­‐equal parts, a small part (9.8 km2, semi-­‐enclosed) submitted to various anthropogenic inputs (French Navy, commercial traffic, raw sewage of urban area, industry) and a large part (42.2 km2), less impacted and open to the sea. The small bay is the final gathering place of the town catchment area streaming. Low tides in the Mediterranean Sea associated with weak currents in the Toulon bay have significant implications on the contaminants accumulation in sediments. Based on a fine scale mapping of sediments contamination carried out in the framework of the CARTOCHIM project, Tessier et al. (2011) have shown that the Toulon bay is hugely polluted, by numerous compounds (metals, metalloids, organo-­‐metallic and organic). For instance, Hg content can reach level as high as 125 µg g-­‐1, 4 orders of magnitude higher than the local background, and the Hg stock was estimated at 26 t. Such huge multi-­‐
contamination status asked numerous scientific questions regarding pollutants modification (e.g. methylation, debuthylation) and dynamic (e.g. dissolved/particulate fractionation) in the sediment and at the water/sediment interface, transfer to the water column and ultimately to the food chain, controlled by different processes such as early diagenesis. Cossa et al. (submitted) have analyzed methylmercury in a large set of sediment samples, covering more than 3 orders of magnitude in terms of total Hg content. The obtained results, compared with ~1300 data gathered from published and unpublished literature, suggested that the MeHg dependence on total Hg in aquatic sediments could be described by a Michaelis-­‐Menten type equation, showing a limit in the bacterial methylation possibly linked to toxic effects and/or a decrease of Hg bioavailability. Further studies have to be performed, which can greatly benefit from the peculiarities of the Toulon bay, to better understand the main processes which controlled the methylation/demethylation rates. Sn speciation (TBT, DBT, MBT and inorganic Sn) has also been studied (Pougnet et al., in preparation). Despite the ban of TBT use as antifouling paint, the levels recorded in surface sediments remained very high, overpassing 4400 ng g-­‐1 (ΣBT). Deeper, the levels increased and showed the successive debuthlyation steps. The obtained results suggested that a non-­‐negligible fraction of inorganic Sn could come from a total debuthylation of BTs species, probably due to the juxtaposition of 2 processes: (1) a fast (photo-­‐
)debuthylation of BTs compounds in the water column during sediment resuspension events, followed after particles settling with (2) a slow (bio-­‐)debuthlyation in suboxic/anoxic sediments. If numerous studies have been performed during or immediately after the use of TBT as antifouling paint, these researches aren't directly transposable to the actual (and future) state. They have to be continued in coastal environments such as the Toulon Bay, to better understand the key parameters which governed the actual debuthylation status either in "normal condition" or in "forced" ones (e.g. storm or dredging resuspension) and to predict the future evolution or 25
50
Jun Jul
Aug Sep Oct Nov Dec Jan 0
15
these toxic species. 10
As (nM)
As (µg g-­‐1)
10
Field campaigns, lab 100
5
1000
experiments and 0
{As} (ppm)
modeling are actually -5
performed to study the -10
dynamic of trace -15
15
100
metals/metalloids in the 10
Fe (nM)
Fe (%)
1000
sediment. For instance, 5
10000
Dang et al. (submitted) 100000
0
have shown the strong {Fe} (%)
-5
link between As and Fe -10
-15
dynamics in surface Jun Jul Aug Sep Oct Nov Dec Jan 0
5
10
sediments, governed by 2013
2012
early diagenesis with a Figure 4: (Left) Monitoring of As and Fe concentrations in sea/pore water,
significant seasonal (Right) and corresponding contents in the solid phase of sediments.
variation (Fig. 4). In 10 Letter WP3 n°2 – September 2013
deeper (anoxic) sediments, As dynamic appeared to be controlled by complexation with sulfides and organic matter, and sorption on various carrier phases. Similar approach on other trace elements will provide a comprehensive view of their dynamic in the sediment and possible transfer to the water column. Studying the possible risks associated with such huge multi-­‐contamination of the sedimentary compartment for the surrounding organisms remains challenging, needing convenient approaches. For instance, filter-­‐feeding organisms such as mussels can be exposed to pollutants both from dissolved and particulate phases. Linking between mussel contamination and sediment one remained anyway not easy. Mussel watch programs have shown that commercialized mussels from the Toulon Bay present a significant Pb anomaly, with contents closed or even over-­‐passing the French limit of consumption (8 µg g-­‐1). Accordingly, Pb sediments pollution could be one possible explanation which still remains to be proven. In such context, Pb stable isotopes (2006, 207 and 208) analysis both in surface/deep sediments from contrasted areas of the Toulon bay and in the 1979-­‐2011 mussel bank (IFREMER) were performed. The obtained results on sediments demonstrated that the sediments of the whole bay were dominantly polluted by a unique source, probably due to the 2nd World War events, an hypothesis which was already suggested regarding the significant correlation between different pollutants in surface/deep sediments (Tessier et al., 2011). Similar marked Pb isotopes signature is observed in all the mussels analyzed from the studied period, which suggest a link between Pb contamination in sediments and in these organisms. Further studies have to be performed to better understand the main contaminant pathway involved. References: • Cossa D., C. Garnier, R. Buscail, F. Elbaz-­‐Poulichet, N. Mikac, N. Patel-­‐Sorrentino, E. Tessier, S. Rigaud, C. Gobeil A Michaelis-­‐Menten type equation for describing methylmercury dependence on total mercury in aquatic sediments. Biogeochemistry, submitted. • Dang D.H, E. Tessier, V. Lenoble, G. Durrieu, D. Omanovic, J.-­‐U. Mullot, H.R. Pfeifer, S. Mounier, C. Garnier. Key parameters controlling arsenic dynamics in coastal sediments, an analytical and modelling approach. Marine Chemistry, submitted. • Fraysse M., C. Pinazo, V. Faure, R. Fuchs, P. Lazzari, P. Raimbault, I. Pairaud. 3D Coupled physical-­‐biogeochemical model development around Marseille’s coastal area (NW Mediterranean Sea): What complexity is required in coastal zone? Plos One, 2013, accepted. • Guigue C., M Tedetti, S Giorgi, M Goutx. (2013) Occurrence and distribution of hydrocarbons in the surface microlayer and subsurface water from the urban coastal marine area off Marseilles, Northwestern Mediterranean Sea. Marine -­‐ B. Oursel, C. Garnier, G. Durrieu, S. Mounier, D. Omanović, Y. Lucas. Dynamic and fate of trace metals in coastal zone impacted by large urban area diffusive inputs: the case of Marseille (France). Marine Pollution Bulletin, , 69, 137-­‐149 • Oursel B., C. Garnier, I. Pairaud, D. Omanović, G. Durrieu, A.D. Syakti, C. Le Poupon, B. Thouvenin, Y. Lucas. (submitted) Behaviour and fate of urban particles in coastal waters: settling rate, size distribution and metals contamination characterization. Estuarine, Coastal and Shelf Science. • Pairaud I., J. Gatti, N. Bensoussan, R. Verney, P. Garreau. (2011) Hydrology and circulation in a coastal area off Marseille: Validation of a nested 3D model with observations. Journal of Marine Systems, 88, 20-­‐33. • Pougnet F., J. Schäfer, L. Dutruch, C. Garnier, E. Tessier, H. Dang, L. Lanceleur, J.-­‐U. Mullot, V. Lenoble, G. Blanc. (In prep) Sources and historical record of tin and butyl-­‐tin species in a Mediterranean bay (Toulon Bay; France). In preparation • Tedetti M., C Guigue, M Goutx. (2010) Utilization of a submersible UV fluorometer for monitoring anthropogenic inputs in the Mediterranean coastal waters. Marine Pollution Bulletin, 60, 350-­‐362. • Tedetti M., R Longhitano, N Garcia, G Guigue, N Ferretto, M Goutx. (2012)Fluorescence properties of dissolved organic matter in coastal Mediterranean waters influenced by a municipal sewage effluent (Bay of Marseilles, France). Environmental Chemistry, 9, 438-­‐449. • Tedetti M., C. Bachet, P. Joffre, N. Ferretto, C. Guigue, M. Goutx. (2013) Development of a submersible fluorometer for the detection of phenanthrene-­‐ and tryptophan-­‐like compounds in marine waters. WOMS’13 workshop, Toulon. • Tessier E., C. Garnier, J.-­‐U. Mullot, V. Lenoble, M. Arnaud, M. Raynaud, S. Mounier. (2011) Study of the spatial and historical distribution of sediment inorganic contamination in the Toulon bay (France). Marine Pollution Bulletin, 62, 2075–2086. • Verney R., C. Jany, B. Thouvenin, I. Pairaud, M. Vousdoukas, C. Pinazo, F. Ardhuin, P. Cann. Sediment transport in the bay of Marseille: role of extreme events. Proceedings of Coastal Dynamics'13, Arcachon, France, 1811-­‐1822. 11 Letter WP3 n°2 – September 2013
International
A MERMEX workshop took place in June 2013 at the Rudjer Boskovic Institute in Zagreb, Croatia. This workshop was co-­‐funded by Eurocean network, Aix Marseille University and LABEX OT-­‐Med. It aims to increase the internationalization of the MERMEX project (now endorsed by SOLAS, IMBER, LOICZ). More specifically, the objectives of the workshop were (1) to organize a coastal marine research and observation network in Mediterranean Sea with Mediterranean and Eurocean scientists; and (2) to better understand impacts of global change on the Mediterranean Sea functioning. Four international projects, partly issued from the discussion during the Zagreb meeting, have been submitted to the ENVIMED call in summer 2013. Two of them are directly related to the WP3 objectives. ARCCHI-­‐MED (Appréciation des impacts liés à la contamination chimique ds zones côtières de la rive Sud du bassin Méditerranéen) involves France, Algeria and Tunisia. COMECOM-­‐Mermex (Contaminants Métalliques dans l’environnement côtier méditerranéen) involves France, Croatia, Algeria, Italia and Lebanon. 12 Letter WP3 n°2 – September 2013