The record of human impact in the sedimentary record at Portus, the harbor of ancient Rome

International audienceThe present study focuses on the analysis of palaeo-pollutions and the sedimentary environments in which they were trapped in the Roman Portus harbor. Portus received heavy-metals pollution both from local foundries, fulling, and tanning and from distal upstream development in Rome. Rome wastewaters, which accounted for up to 3 percent of the total Tiber discharge, were forwarded to Portus through a network of canals (Canale Romano and Canale Trasverso) connecting the river to the sea. In this manner, harbor basins accumulated both allochthonous and autochthonous heavy metals. We determined major and trace element concentrations as well as Pb isotope compositions in a high-resolution set of samples from sediment cores recovered in the Portus area. Principal component analysis of elements that are less prone to the influence of human activities, such as Ca, Mg, Mn, Zr, K, Al, Ti, Na, Sr, and Mn, was used in conjunction with metallic elements to break down the sedimentary load into local and regional components. The record of Pb concentrations and isotopic compositions reveals an overall general trend on which other signatures are superimposed. The geochemical background of the Tiber catchment (24.7-26.2 ppm Pb and 206 Pb/ 207 Pb ~ 1.198) represents geologically young (model age Tm <50 Ma) Pb derived from natural runoff over young sediments and volcanics in the Latium. From the 1 st century AD to the end of the roman period, the harbor regime evolved from a dominant fluvial (enriched in Al, Ti, Mg, K, and Zr) to a more marine influence (high Ca/Mg, Na/Al, Sr, and CaCO3) in the upper part of the harbor unit. "Imperial" Pb (90.5-35.4 ppm Pb and 20

Geochemical investigation of a sediment core from the Trajan basin at Portus, the harbor of ancient Rome

International audiencea journal published by Elsevier. The attached copy is furnished to the author for internal non-commercial research and education use, including for instruction at the authors institution and sharing with colleagues. Other uses, including reproduction and distribution, or selling or licensing copies, or posting to personal, institutional or third party websites are prohibited. In most cases authors are permitted to post their version of the article (e.g. in Word or Tex form) to their personal website or institutional repository. Authors requiring further information regarding Elsevier's archiving and manuscript policies are encouraged to visit: a b s t r a c t From the 1st century AD and for the duration of the Roman Empire, the Portus complex was the main harbor of Rome. Its location on the Tiber delta next to the Tyrrhenian Sea produced rapid environmental changes that, together with historical vicissitudes, largely determined the fate of the harbor. We have assembled data on the mineralogy, sedimentology, geochemistry, and ostracod populations of a sediment core drilled in the access channel of the hexagonal basin of Trajan, with the expectation that such a combined data set will shed new light on how the connections of the inland Trajan basin with the Tiber river, the earlier Claudius harbor on the nearby shoreline, and the sea evolved through the centuries. The data define four distinct periods which geochemistry characterizes by different conditions of salinity and oxygenation. These in turn can be related to historical periods and events by means of 1

Dynamics of chemical pollution fluxes throughout the Rhône River catchment and at its outlet (France)

International audienceLand-based human activities are known to be the largest sources of marine pollution. Once released into the hydrographic networks, metals and hydrophobic organic micropollutants reach coastal ecosystems mainly through suspended particulate matter (SPM). As a result, the accurate assessment of micropollutant fluxes discharged by rivers is critical to appraise the related environmental and health risks. Unfortunately, our current knowledge on pollutant fluxes in large river systems is limited, especially on their inter-seasonal dynamics. This is typically the case for the Rhône River, the largest source of freshwater and SPM of the Western Mediterranean Sea. Thanks to the comprehensive monitoring network implemented within the Rhône catchment, covering about 80 % of its area, daily time-series of micropollutant fluxes over the 2008-2018 period have been computed. Firstly, through the concentration levels of 29 organic and inorganic micropollutants, the stations can be ranked and the sub-catchments chemical fingerprints can be used to identify the main anthropogenic and geographical pollution sources. Secondly, the present work explores the range, seasonality, and inter-annual averages of pollutant fluxes at the Rhône River outlet and from its main tributaries. Thus, the mean inter-annual fluxes of particulate pollutants discharged to the Mediterranean are about 61 kg yr-1 for Ʃ5PCB, 3 t yr-1 for Ʃ13PAH, 1802 t yr-1 for Ʃ9TM (trace metal elements), 97 kg yr-1 for glyphosate, and 220 kg yr-1 for AMPA. Moreover, we observe a strong seasonal variability. Indeed, the inter-annual monthly pollutant fluxes display a three-mode profile with peaks centered in November, January, and May-June, respectively. During those months, two thirds of the total micropollutant annual fluxes are released at the Rhône River outlet. These micropollutant discharge periods closely follow the modes of the complex hydrological regime of the Rhône River combining Mediterranean, oceanic pluvial, and nival floods. The deconvolution of the three-mode profile of micropollutant fluxes shows that the Durance, Saône, and Isère rivers contribute at about 19% of the Mediterranean component, 18% of the oceanic pluvial component, and 59% of the nival component, respectively

Contribution du SIG à la reconstitution des processus de progradation de la Medjerda : Quels enjeux pour le port d'Utique ?

Cité des Sciences de TunisInternational audienc

The record of human impact in the sedimentary record at Portus, the harbor of ancient Rome

International audienceThe present study focuses on the analysis of palaeo-pollutions and the sedimentary environments in which they were trapped in the Roman Portus harbor. Portus received heavy-metals pollution both from local foundries, fulling, and tanning and from distal upstream development in Rome. Rome wastewaters, which accounted for up to 3 percent of the total Tiber discharge, were forwarded to Portus through a network of canals (Canale Romano and Canale Trasverso) connecting the river to the sea. In this manner, harbor basins accumulated both allochthonous and autochthonous heavy metals. We determined major and trace element concentrations as well as Pb isotope compositions in a high-resolution set of samples from sediment cores recovered in the Portus area. Principal component analysis of elements that are less prone to the influence of human activities, such as Ca, Mg, Mn, Zr, K, Al, Ti, Na, Sr, and Mn, was used in conjunction with metallic elements to break down the sedimentary load into local and regional components. The record of Pb concentrations and isotopic compositions reveals an overall general trend on which other signatures are superimposed. The geochemical background of the Tiber catchment (24.7-26.2 ppm Pb and 206 Pb/ 207 Pb ~ 1.198) represents geologically young (model age Tm <50 Ma) Pb derived from natural runoff over young sediments and volcanics in the Latium. From the 1 st century AD to the end of the roman period, the harbor regime evolved from a dominant fluvial (enriched in Al, Ti, Mg, K, and Zr) to a more marine influence (high Ca/Mg, Na/Al, Sr, and CaCO3) in the upper part of the harbor unit. "Imperial" Pb (90.5-35.4 ppm Pb and 20

Contribution du SIG à la reconstitution des processus de progradation de la Medjerda : Quels enjeux pour le port d'Utique ?

Cité des Sciences de TunisInternational audienc

Exploration of the maritime façade of Utica: the potential location of the Phoenician and Roman harbours

peer reviewedAccording to ancient literary tradition, Utica is considered to be one of the first three Phoenician foundations in the Western Mediterranean, supposedly founded in 1101 BC by Levantines from Tyre. In the Phoenician and Roman periods, it was an important merchant coastal town, on a promontory facing the sea. Over the centuries Utica lost its access to the sea, and its ports silted up as a consequence of the activity of the wadi Medjerda, which flowed to the south of the city. Despite over a century of investigation by archaeologists and associated researchers, the location of the city’s harbour structures from the Phoenician and Roman periods remains unknown, buried under sediments resulting from the progradation of the Medjerda. Based on the study of sedimentary cores, the research presented here highlights the existence of a long maritime façade to the north of the Utica promontory in Phoenician and Roman times. A deep-water marine environment is attested in the former bay from the 6th mill. BC and the depth of the water column along the northern façade was still 2 m around the 4th – 3rd c. BC. Another core to the east of the Kalaat El Andalous promontory showed the possibilitythat this sector was a sheltered harbour during the Phoenician and Roman periods. This paper illustrates the contribution of geoarchaeology to address this archaeological problem and to understand the relations of this important port city with the sea

The economic resilience of Carthage during the Punic Wars: Insights from the sediments of the Medjerda delta around Utica (Tunisia)

While the Punic Wars (264–146 BC) have been the subject of numerous studies, generally focused on their most sensational aspects (major battles, techniques of warfare, geopolitical strategies, etc.), curiously, the exceptional economic resilience of the Carthaginians in the face of successive defeats, loss of mining territory, and the imposition of war reparations has attracted hardly any attention. Here, we address this issue using a newly developed powerful tracer in geoarchaeology, that of Pb isotopes applied to paleopollution. We measured the Pb isotopic compositions of a well-dated suite of eight deep cores taken in the Medjerda delta around the city of Utica. The data provide robust evidence of ancient lead–silver mining in Tunisia and lay out a chronology for its exploitation, which appears to follow the main periods of geopolitical instability at the time: the Greco-Punic Wars (480–307 BC) and the Punic Wars (264–146 BC). During the last conflict, the data further suggest that Carthage was still able to pay indemnities and fund armies despite the loss of its traditional silver sources in the Mediterranean. This work shows that the mining of Tunisian metalliferous ores between the second half of the fourth and the beginning of the third century BC contributed to the emergence of Punic coinage and the development of the Carthaginian economy

Palaeogeographical and palaeoenvironmental reconstruction of the Medjerda delta (Tunisia) during the Holocene

International audienceThe progradation of the Medjerda delta has been the subject of many studies since the 19th century. Thescale and the rapidity of this phenomenon interested researchers in various fields early on, such asgeomorphology, geology, palaeogeography, history, archaeology, or geoarchaeology. Indeed, the deltaprograded by around 10 km over 3 millennia. At the time of its foundation supposedly at the end of the12th century BC, the Phoenician city of Utica was located on a promontory bathed by the sea, but thesediments carried by the Medjerda progressively sealed the bay, leaving the tip of the Utica promontorynow 10 km inland. This area is therefore an exception to the general pattern along the Tunisian coast,since as over the same period everywhere else there is a regression of the coastline, owing to a sea levelrise of several decimeters. Based on multi-proxy analyses of two coring transects, this paper aims toreconstruct the palaeoenvironments and the palaeogeography of the Medjerda delta’s progradation sincethe mid-Holocene, some aspects of which are described in ancient sources. The results highlight inparticular an episode of high-intensity flooding around the 4th century AD, which is consistent withepisodes of high floods and an increase in sedimentation rates recorded in the watershed at the end ofthe Roman period. The gradual abandonment of the city of Utica can certainly be related to the activity ofthe Medjerda River, but our results show that it is because of an increase of fluvial sediment contributionin connection with an erosive crisis in the headwaters, and not because of the change of course of theriver, which had occurred long before