Christina Zeri

TRACE METAL BEHAVIOUR DURING SUMMER IN A STRATIFIED MEDITERRANEAN SYSTEM: THE LOUROS ESTUARY (GREECE)

Trace metals (Al, Pb, Zn, Cr, Cu, Ni, Fe, Mn) were studied in waters (dissolved and particulate phases) and sediments of the Louros Estuary in the Amvrakikos Gulf, one of the most important European wetlands located at the NW coast of Greece.The study system is small, with a relatively narrow mixing zone, typical for Mediterranean estuaries. Particular emphasis was given to understanding the conditions prevailing in summer. During this season saline water intrudes the estuary along the river bed, despite the existing shallow sill, and forms a thin salt-wedge water mass, which occupies the near bottom layer with its thin end pointed upstream.Particulate metal concentrations within this saline bottom layer are considerably higher than in the riverine and marine sections of the estuary. Since the metal content of particles collected upstream is higher than that of the marine ones, there is a clear evidence that the salt-wedge acts as a ‘sink’ for most metals during the summer.Coexistance in the same zone of high dissolved metal concentrations indicate that loosely associated metals are desorbed from riverine particles, whereas newly formed suspended matter is deposited together with particles, transported by the river. The accumulation of metals in the near bottom layer affects directly their distribution in the sediments. The maximum concentrations of the metal fraction which is loosely held in sediments, are found primarily at the same site. The distribution of the ‘non-labile’ metal fraction of the sediments (particularly for Cu and Pb) is broadly constant throughout the estuary, confirming the absence of any significant natural or industrial point sources, at the lower part of the river.However, the analysis of sediment cores reveals an enrichment of this metal fraction at the top, near surface sections of the mouth area, indicating relatively recent pollution.

Microplastic Abundance and Polymer Types in a Mediterranean Environment

Microplastics have become a more and more dominant threat to marine ecosystems. The ubiquity of microplastics is one of the major problems; from the sea surface and water column to the beach and seabed sediment or even ingested by marine organisms, small plastic particles have been found. This study is focused on monitoring and assessment of microplastic pollution (plastic particles <5 mm) on the sea surface, in beach sediments, and in marine biota in the Corfu Island area (Northern Ionian Sea). Microplastics detected in samples from water, sediment, fish gut or mussel tissue were stereoscopically observed, categorized by shape, size, colour and their polymer type was identified by FTIR analysis. Microplastic items in sea surface water ranged from 0 to 1.61 particles/m2. Microplastics average abundance in beach sediments ranged from 17 to 95 items/m2. Out of all fish and mussels tested, the percentage of individuals detected with microplastics was 41.25% and 46.25% respectively. The average abundance of small microplastics (<1 mm) in positive fish and mussels was 1.66 particles/fish and 1.83 particles/mussel, while the no large microplastic (1–5 mm) was detected. The majority of microplastics in all environmental compartments were identified as polyethylene. Relations in size classes and polymer type among environmental compartments are investigated. Results describe a holistic image of the pollution caused by microplastics in the study area and can be useful for an integrated microplastic monitoring.

Floating plastics in Adriatic waters (Mediterranean Sea): From the macro- to the micro-scale

Macro- and microplastics abundances were determined in the Adriatic Sea following the MSFD TG10 protocol. The studied areas included populated gulfs, river outlets and offshore waters in five Adriatic countries. The use of small ships enabled us to detect small sized plastics (2.5-5 cm) and record average macroplastics densities of 251 ± 601 items km-2, one order of magnitude higher than previously considered. Results from manta net tows for microplastics revealed an average abundance of 315,009 ± 568,578 items km-2 (217 ± 575 g km-2). We found significantly higher microplastics abundances in nearshore (≤4 km) than in offshore waters (>4 km) and this trend seems to affect also the small sized macro plastic fragments (2.5-5 cm). The dominant polymers were polyethylene and polypropylene while the presence of some rare polymers and waxes used in food and dentistry indicated waste water treatment plants as potential sources of microplastics.

Chemical Evaluation of Compost Produced at a Large Greek Mechanical Biological Treatment Plant: Metal Availability and Phytotoxicity

ABSTRACT The present work investigates the impact of municipal solid waste mechanical separation and industrial composting on the metal content of composts and assesses the availability of Cu, Cd, Cr, Pb, and Zn at different maturation stages of compost produced at the largest mechanical biological treatment plant in Greece. Substantial metal contamination of composts was found to take place within the industrial facility, attributed to segmentation and sorption mechanisms during composting. In fresh compost, Zn is present in mobile fractions (41%), Cu is mostly held on the less mobile organic phases (57%), Cd is mostly present in bioavailable forms (51%), whereas Pb and Cr are associated with less mobile phases, such as Fe-Mn oxides and organic molecules. Cd, Cu, and Zn migrate to more inert phases during compost maturation, paralleled by the decrease of overall metal leachability. Cu and Pb concentrations (mg kg−1) exceeded the permissible limits in both composts (Fresh: Cu: 213 ± 48, Pb: 128 ± 69; Mature: Cu: 263 ± 1, Pb: 158 ± 29) and water leachates (Fresh: Cu: 106 ± 4, Zn: 126 ± 13; Mature: Cu: 50 ± 0.50, Zn: 118 ± 20). Nevertheless, toxic effects were not observed in monocot, dicot, or aquatic biosensor plants as indicated by radicle and shoot growth and visual quality ratings. Since metal availability in composts is related to their leaching potential, metal speciation studies should be conducted in leachates for the appropriate characterization of industrial composts.

An integrated magnetic-chemical approach to the study of iron in Rhône estuary sediments

Abstract Measurement of magnetic parameters in combination with the partitioning of iron in various sediment fractions (authigenic-lithogenous) have been used in order to obtain information concerning the fate of iron within the sediment. Through this approach, it is shown that in the Rhone estuary sediments there is a dominance of the lattice-held iron, represented by the abundance of ferrimagnetic minerals. A considerable part (∼ 17 %) of the iron present is authigenic, associated mainly with the oxide-hydroxide forms and originating from direct fluvial inputs and in situ diagenetic processes. Iron oxides and hydroxides are formed in the water column and/or porewaters and are accumulated mainly in the surface layer (0–2 cm) of the sediment column corresponding to the mineral goethite.

Marine litter on the beaches of the Adriatic and Ionian Seas: An assessment of their abundance, composition and sources

The abundance, composition and sources of marine litter were determined on beaches located in the seven countries of the Adriatic-Ionian macroregion, namely Albania, Bosnia and Herzegovina, Croatia, Greece, Italy, Montenegro and Slovenia. A total of 70,581 marine litter items were classified and recorded through one-year long surveys carried out in 31 sites. The average litter density of 0.67 items/m2 found within this study is considered to be relatively high. The beaches investigated differed in terms of human-induced pressures; their majority is classified either as semi-urban or semi-rural, while very few beaches could be characterized as urban or remote/natural. The majority of litter items were made of artificial/anthropogenic polymer materials accounting for 91.1% of all litter. Litter from shoreline sources accounted for 33.4% of all litter collected. The amount of litter from sea-based sources ranged in the different countries from 1.54% to 14.84%, with an average of 6.30% at regional level.