6 research outputs found
The influence of the Evros River on the recent sedimentation of the inner shelf of the NE Aegean Sea
Abstract The transboundary Evros River discharges into the Alexandroupolis Gulf, located in the inner shelf of the northeastern Aegean Sea, where it has formed an extended delta. Grain-size and mineralogical analyses of five sediment cores, collected in the subaqueous delta, provide the following information about recent sedimentation processes in the northeastern part of the Aegean shelf: (a) river mouth deposits, consisting of coarse-grained sediments, are mainly deposited in front of the active mouth, whilst some sandy material is expected to be transported alongshore by nearshore currents; (b) delta front deposits are characterised by fine-grained sediments that include evidence of human activities which have taken place, in a more intense way, since the 1950s; and (c) prodelta deposits are represented by almost uniform riverine mud that cover the pre-existed relict sands of the shelf, indicating also the limit (some 15 km to the SW) of the influence of riverine sedimentation on the seabed of the inner shelf of the Alexandroupolis Gulf
Assessment of the physical impact of a short-term dredging operation on a semi-enclosed environment: South Euboean Gulf, Greece
The potential influence of short-period (May-June 2012) dredging
activities (for the installation of a submarine gas pipeline) on
physical properties of the marine environment of two shallow-water sites
in the Aliveri and Varnavas areas of South Euboean Gulf (Greece) has
been evaluated. During the dredging operation in Varnavas, the induced
dredge plume traveled up to 750 m from the shoreline, featured by light
attenuation coefficient (c(p)) maxima of 4.01-4.61 m(-1) and suspended
particulate matter (SPM) concentrations up to 6.01 mg L-1. After
dredging the previous parameters reduced to the ambient seawater
condition, 0.45 m(-1) and < 2.8 mg L-1 on average, respectively.
Likewise in Aliveri, the dredging-associated sediment plume drifted
offshore up to 400 m from the shoreline, characterized by c(p) maxima of
2.11-4.86 m(-1) and SPM concentrations up to 13.07 mg L-1. After the
completion of the excavation and trenching activities, the c(p) and SPM
values were restored to the pre-disturbance condition, 0.6 m(-1) and <
2.2 mg L-1 on average, respectively. The migration of the dredge plume
in both dredging sites was accomplished through the formation of
intermediate and benthic nepheloid layers, whose development and
evolution were governed by seawater stratification and flow regime. The
dredging-derived SPM levels appeared to increase within a distance of no
more than 300 m from the shoreline (near-field zone). Based on data from
the literature, this SPM enhancement together with the deposition of a
post-dredging residual mud veneer in the near-field zone could
deteriorate local marine biota, but in a reversible way
Assessment of the Coastal Vulnerability to the Ongoing Sea Level Rise for the Exquisite Rhodes Island (SE Aegean Sea, Greece)
The foreseeable acceleration of global sea level rise could potentially
pose a major threat to the natural charm and functional integrity of the
world-renowned tourist coastal attractions of Rhodes Island, as a result
of the anticipated increasing frequency of flooding and erosion events.
Hence, this study aims to determine the most vulnerable segments (in
terms of physical impact) of the Rhodes coastline through the widely
accepted coastal vulnerability index (CVI), applying a combination of
well-known, broadly used approaches and methods. The frequency
distribution of the current CVI along the island’s coastline suggests a
rather worrying high to very high vulnerability of 40%. In addition, a
CVI projection to the end of the 21st century (based on the
Intergovernmental Panel on Climate Change predictive scenarios)
indicates an enhancement of the total vulnerability by 48%, mainly
focused on the majority of the western coastline. Hence, a considerable
number of popular coastal destinations in the island shall remain under
unignorable threat and, therefore, coastal managers and decision-makers
need to hatch an integrated plan to minimize economic and natural
losses, private property damage and tourism infrastructure deterioration
from flooding and erosion episodes, which will most likely be
intensified in the future
The impact of flash-floods on the adjacent marine environment: the case of Mandra and Nea Peramos (November 2017), Greece
Heavy metal contamination status in Greek surface waters: A review with application and evaluation of pollution indices
Authigenic carbonate mineral formation in the Pagassitikos palaeolake during the latest Pleistocene, central Greece
The Pagassitikos Gulf in Greece is a semi-enclosed bay with a maximum depth of 102 m. According to the present-day bathymetric configuration and the sea level during the latest Pleistocene, the gulf would have been isolated from the open sea, forming a palaeolake since ~32 cal. ka b.p. Sediment core B-4 was recovered from the deepest sector of the gulf and revealed evidence of a totally different depositional environment in the lowest part of the core: this contained light grey-coloured sediments, contrasting strongly with overlying olive grey muds. Multi-proxy analyses showed the predominance of carbonate minerals (aragonite, dolomite and calcite) and gypsum in the lowest part of the core. Carbonate mineral deposition can be attributed to autochthonous precipitation that took place in a saline palaeolake with high evaporation rates during the last glacial–early deglacial period; the lowest core sample to be AMS 14C dated provided an age of 19.53 cal. ka b.p. The palaeolake was presumably reconnected to the open sea at ~13.2 cal. ka b.p. during the last sea-level rise, marking the commencement of marine sedimentation characterised by the predominance of terrigenous aluminosilicates and fairly constant depositional conditions lasting up to the present day