Occurrence, sources and water column distribution trends of suspended particle-associated aliphatic and polycyclic aromatic hydrocarbons in the open northeastern Mediterranean Sea

Herein, we study the occurrence and water column distribution trends of suspended particle-associated aliphatic (AHCs) and polycyclic aromatic hydrocarbons (PAHs) collected from 36 offshore/deep sea locations across the open northeastern Mediterranean Sea. Total concentrations of the determined compounds fall within the range previously reported for non-polluted coastal and open sea locations worldwide. Mixed natural and anthropogenic sources were evident for the studied compounds, based on their molecular profile and several diagnostic indices. In all cases, an enhanced fossil signal typifying chronic oil pollution was evident along the water column. AHCs and PAHs mixtures characteristics varied significantly within the studied sub-regions, highlighting the importance of inputs from various point sources and dispersion pathways. The circulation characteristics of water masses along with biogeochemical features impact on the water column distribution trends and overall fate of the determined compounds in the study area.

Organic contaminants levels, distribution and risk assessment in Jeddah marine coastal zone sediments

Herein, various organic contaminants were determined in surface sediments collected from the Jeddah coastal zone, Saudi Arabia, to assess their levels, origin and probable toxic effects on marine organisms. High hydrocarbons concentrations, indicative of an enhanced pollutant burden, were recorded in the Jeddah Lagoon (mean value 4100 mg/kg for total aliphatic hydrocarbons (∑AHC) and 5800 μg/kg for total polycyclic aromatic hydrocarbons (∑PAH)), whereas mean values in Mena Jeddah were 258 mg/kg for ∑AHC and 615 μg/kg for ∑PAH. By using molecular diagnostic ratios/indices and applying Positive Matrix Factorization, petroleum related pollution seems to predominate in Jeddah lagoons, whereas carcinogenic contaminants of pyrolytic origin were dominant in Mena Jedda. Additionally, municipal wastewaters were identified as a major source of pollution in Jeddah lagoons. Comparison of the concentrations of individual PAHs and polychlorinated biphenyls with sediment quality guidelines indicates that, despite their high total values, adverse biological effects are unlikely to occur.

Thirty years of a bottom oxygen depletion-renewal cycle in the coastal yet deep environment of the West Saronikos Gulf (Greece): Its drivers and the impact on the benthic communities

In the period 1987-2017, a series of physical and chemical measurements related to oxygen variability at a trough area with a maximum depth of ~420 m in the West Saronikos Gulf, reveal the following: In the early 90s, deep winter mixing occurred resulting in an oxygenation down to ~420 m followed by an oxygen decline. This decline reached near-bottom hypoxic conditions (O2 < ~62 μM (μmol/L)) after 1998, while a denitrification phase occurred after 2000 and a complete bottom anoxia in 2005. In June 2012, an oxygenation down to ~350 m was detected that most likely occurred in winter 2012. The 2012 oxygenation raised the until-then anoxic bottom concentrations to hypoxic ones in the years towards 2017 via vertical diffusive oxygen transfer. Observations of the benthic communities during the hypoxia, severe hypoxia (O2 < ~15 μM) and oxygen recovery phases showed a peak of opportunists in the hypoxia and a long faunal depletion in the severe hypoxia phases. A reversal in the benthic community structure appeared after the oxygenation of 2012 with the (re)appearance of opportunists while, in 2017, the community showed signs of retreat to earlier stages. The main anthropogenic pressure that could tentatively affect the oxygen concentration in the study area is posed by the Athens treated-sewage outfall at ~40 km away from the trough, which inputs organic matter into the Saronikos Gulf through effluent water of reduced salinity that, in addition, may alter the stratification opposing the vertical mixing. We show that the treated sewage output had no influence on a) the stratification, b) the particulate and dissolved organic carbon and c) the sewage-derived organic matter. Instead, the long-term dissolved oxygen variability with the deep renewal events was mostly driven by the large-scale atmosphere-ocean conditions (heat exchange and evaporation-minus-precipitation budget) that determine the hydrographic characteristics and the winter mixing.

Pollution status determination using trace metals and organic contaminants of the water column in coastal areas of the Red Sea and the Gulf of Aqaba: A baseline assessment

Herein, we aim to provide a baseline assessment of the pollution status of the water column in coastal areas of Saudi Arabia (Red Sea and the Gulf of Aqaba), using trace metals (Cd, Co, Cr, Cu, Ni, Pb and Zn), total petroleum hydrocarbons (TPHs) and polycyclic aromatic hydrocarbons (PAHs), in seawater samples obtained from 71 sampling stations in June-July 2021. Concerning trace metals, the maximum concentrations for Co, Cu and Ni were detected in Al-Shuqaiq, whereas the highest Pb and Zn concentrations were found in the Jeddah lagoon waters. Elevated concentrations of TPHs and the highest sum of PAHs were recorded in surface waters of Al Lith, Jeddah lagoon and Jeddah Mena. Overall, the concentrations of all trace metals, TPHs and individual PAHs for which environmental standards have been stipulated for the Kingdom of Saudi Arabia fall well below the threshold values.

Trace metals and polycyclic aromatic hydrocarbons in the Eastern Mediterranean sediments: Concentration ranges as a tool for quality control of large data collections

Assessing the status of marine pollution at regional and sub-regional scales requires the use of comparable and harmonized data provided by multiple institutions, located in several countries. Standardized data management and quality control are crucial for supporting a coherent evaluation of marine pollution. Taking the Eastern Mediterranean Sea as a case study, we propose an approach to improve the quality control procedures used for sediment pollution data, thus supporting a harmonized environmental assessment. The regional ranges of contaminant concentrations in sediments were identified based on an in-depth literature review, and the lowest measured concentrations were evaluated to determine the "background concentrations" of chemical substances not yet targeted in the Mediterranean Sea. In addition, to verify the suitability of the approach for validating large data collections provided by multiple sources, the determined ranges were used to validate a regional dataset available through EMODnet data infrastructure.

Polycyclic aromatic hydrocarbons in surface sediments of the Aegean Sea (eastern Mediterranean Sea)

In this study, we provide baseline data on the composition, major sources and mechanisms driving the distribution of polycyclic aromatic hydrocarbons (PAHs) mixtures in surficial sediments collected from 43 offshore and open/deep sea locations across the north, central and south Aegean Sea. The determined total concentrations of the considered PAH compounds were generally low, comparable to those reported in relatively non-polluted coastal and open/deep Mediterranean marine sites. Their molecular profile and diagnostic indices reveal mixed contributions from both pyrolytic and petrogenic sources across the study area. Organic carbon exerts an important control on the transport and ultimate accumulation of PAHs, however, the presented results highlight a significant variability in sedimentary PAHs concentrations and compositional patterns within the studied Aegean Sea sub-regions. This could be likely attributed to a combination of distinct hydrological and biogeochemical characteristics, surface and near bottom water mass circulation patterns and the relative importance of PAH sources.

Imprint and short-term fate of the Agia Zoni II tanker oil spill on the marine ecosystem of Saronikos Gulf

In this study we investigate the spatial and temporal imprint of the September 2017 Agia Zoni II tanker heavy fuel oil spill on the marine ecosystem of Saronikos Gulf (Greece). Based on the chemical fingerprinting approach, by means of gas chromatography - flame ionization detector, gas chromatography-mass spectrometry and the use of various diagnostic ratios, we characterize changes in the composition of the spilled oil at various sampling sites and evaluate major mechanisms affecting its fate i.e. dissolution/dispersion, evaporation, biodegradation, photo-oxidation and sedimentation during the first six months from the spill. Overall, the main effects of the incident were confined to the coastal zone during the first three months after the spill, where an extended petroleum imprint was recorded in many cases, with the determined concentrations of the total petroleum hydrocarbons and polycyclic aromatic hydrocarbons falling within the highest range of concentrations previously reported for similar oil spill incidents worldwide. In the first three months following the spill the oil was affected by a combination of volatilization, rapid biodegradation and photodegradation, the later playing a role in its early days weathering. Concerning sediments, an imprint related to the incident was recorded in a few cases, being, however, mild in respect to the high chronic petroleum-associated anthropogenic background of the impacted area.

Dataset on the imprint of the Agia Zoni II tanker oil spill on the marine ecosystem of Saronikos Gulf

These data relate to the research article entitled “Imprint and short-term fate of the Agia Zoni II tanker oil spill on the marine ecosystem of Saronikos Gulf” by Parinos et al., 2019 [1]. The dataset includes the concentrations of 32 individual compounds/groups of polycyclic aromatic hydrocarbons (PAHs) determined in 235 seawater samples and 55 sediment samples analyzed during the monitoring survey conducted by the Hellenic Centre for Marine Research (H.C.M.R.) following the September 2017 Agia Zoni II heavy fuel oil (HFO) spill incident in Saronikos Gulf, Greece. The survey effort included 69 seawater sampling sites, of which 55 coastal and 14 open sea areas, and 22 sediment sampling sites across the inner Saronikos Gulf, aiming to assess the spatial and temporal imprint of the spilled oil during the first six months from the incident. The data were acquired by means of gas chromatography - mass spectrometry, following proper pre-treatment of the collected samples. This dataset is, to the best of our knowledge, the very first PAHs record related to the Agia Zoni II oil spill incident, that should be of interest for future scientific research on this and HFO spills in general.

A Biomass Upscale System for the Marine Dinoflagellate Prorocentrum lima and the Production of Bioactive Lipophilic Toxins

Biotechnological applications of toxic marine dinoflagellates include seafood safety and biomedical, pharmaceutical and research purposes of their toxins among other bioproducts and bioactive compounds that they produce. The supply of sufficient quantities of phycotoxins for investigational uses remains in demand. Some of these toxins, available in small amounts, are quite expensive while their chemical synthesis is complex and costly. However, some quantities of these toxins could be produced with mass cultures of the appropriate dinoflagellates, which are however difficult to handle. Prorocentrum lima is a cosmopolitan marine dinoflagellate, which synthesizes toxins that cause a diarrheic syndrome to humans through the consumption of contaminated shellfish and fish (Diarrheic Shellfish Poisoning, DSP). The aim of this study was to design and develop a biomass upscale system for the production of the lipophilic toxins okadaic acid (OA) and dinophysistoxin 1 (DTX1) from the produced biomass of Prorocentrum lima. In our study, P. lima was grown in large scale semi-continuous cultures under controlled laboratory conditions. The maximum biomass produced was 20690 cells/mL. Maximum toxin production was 63.66 ng/mL for OA and 8.07 ng/mL for DTX1. Toxin quota in P. lima cells was 88.7% OA and 11.3% DTX1. The produced culture volume was 300 L and the total volume capacity of the upscale system could reach 500 L.Int. J. Appl. Sci. Biotechnol. Vol 5(4): 479-485

Occurrence and spatial distribution of 158 pharmaceuticals, drugs of abuse and related metabolites in offshore seawater

The occurrence and spatial distribution of 158 pharmaceuticals and drugs of abuse were studied in seawater of the Eastern Mediterranean Sea (Saronikos Gulf and Elefsis Bay in central Aegean Sea). This area is affected by various anthropogenic pressures as it receives the treated wastewater of the greatest Athens area and off-shore input fluxes. This study constitutes the largest one in terms of number of analytes in this environmental compartment. It provides the first evidence on the occurrence of several pharmaceuticals in marine environment including amoxicillin, lidocaine, citalopram or tramadol, among others. 22 samples were collected at three different depths in 9 sampling stations in order to assess the presence and the spatial distribution of the target compounds. A multi-residue method based on solid phase extraction and liquid chromatography coupled to tandem mass spectrometry was developed for the determination of the 158 target substances and validated for seawater sample analysis. 38 out of the 158 target compounds were detected, 15 of them with frequencies of detection equal to or higher than 50%. The highest detected values corresponded to amoxicillin, caffeine and salicylic acid, with concentrations in the range of < 5.0-127.8 ng L(-1); 5.2-78.2 ng L(-1) and < 0.4-53.3 ng L(-1), respectively. Inputs from the wastewater treatment plant (WWTP) of Athens revealed to be the main source of pollution in the Inner Saronikos Gulf, whereas, other anthropogenic pressures such as contamination from shipping activity, industrial effluents, dredging and/or inputs from land proved to be also relevant. Τhe concentrations of some compounds varied significantly with depth suggesting that currents play an important role in the dilution of the target compounds.

Biochemical biomarker responses to pollution in selected sentinel organisms across the Eastern Mediterranean and the Black Sea

Pollution effects were assessed by means of biochemical biomarkers (catalase, glutathione S-transferase and acetylcholinesterase activities, and metallothioneins content) in five species at selected coastal sites across the Eastern Mediterranean and the Black Sea. The mussel Mytilus galloprovincialis, a well-established sentinel species, was investigated in the Adriatic Sea, Aegean Sea, and Black Sea. The mussel Brachidontes pharaonis and the striped red mullet Mullus surmuletus were used in the Levantine Sea where M. galloprovincialis is not present. The white seabream Diplodus sargus sargus and the gastropod Rapana venosa were additionally sampled in the Adriatic and the Black Sea, respectively. Mussels showed catalase, glutathione S-transferase, and acetylcholinesterase responses to pollution in most geographical areas while the response of metallothioneins was restricted to a few sites. R. venosa showed marked responses of catalase and metallothioneins whereas both fish species did not generally exhibit variations in biomarker values among sites. The approach based on the reference deviation concept using the "Integrated Biological Responses version 2" index was useful for the interpretation of overall biomarker responses.

A MSFD complementary approach for the assessment of pressures, knowledge and data gaps in Southern European Seas: The PERSEUS experience

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-analysis of existing literature on pressure/impact/knowledge gaps summarized in tables related to the MSFD descriptors, discriminating open waters from coastal areas. A comparative assessment of the Initial Assessments (IAs) for five SES countries has been also independently performed. The comparison between meta-analysis results and IAs shows similarities for coastal areas only. Major knowledge gaps have been detected for the biodiversity, marine food web, marine litter and underwater noise descriptors. The meta-analysis also allowed the identification of additional research themes targeting research topics that are requested to the achievement of GES.

Impacts of dredged-material disposal on the coastal soft-bottom macrofauna, Saronikos Gulf, Greece

Dredged sediments derived by the low course and estuary of the metropolitan river of Athens (Kifissos River) were dumped every day for 21 months to an open-sea site in the Saronikos Gulf. The spoil-ground and surrounding area was monitored prior, during and post to dumping for 24 months, over 6-month intervals. Dumping significantly changed the granulometry of the pre-existing superficial sediments to finer-grained only in the spoil ground and increased the sediment contamination load (aliphatic, polycyclic aromatic hydrocarbons and heavy metals) throughout the study area. Microtox® SPT showed that sediment toxicity levels were high at almost all sampling stations. During dumping, burial of natural soft-bottom habitats degraded severely the communities of the spoil-ground resulting in an almost azoic state, as well as significantly declined the species number and abundance of benthic communities in locations up to 3.2 km away from the spoil-ground, due to dispersion of the spoil and smothering. Benthic indices on the surrounding sites were significantly correlated with hydrocarbon concentrations and sediment toxicity levels. Post to dumping, the macrofauna communities of the spoil-ground were still significantly degraded, but the surrounding areas showed patterns of recovery. However, the high concentrations of aliphatic, polycyclic aromatic hydrocarbons and levels of toxicity persisted in the sediments after the ceasing of dumping operations in the study area, implying the ecological hazard imposed on the area.

Effects of olive oil wastes on river basins and an oligotrophic coastal marine ecosystem: a case study in Greece

This work aims to contribute to the knowledge of the impacts of olive oil waste discharge to freshwater and oligotrophic marine environments, since the ecological impact of olive oil wastes in riverine and coastal marine ecosystems, which are the final repositories of the pollutants, is a great environmental problem on a global scale, mostly concerning all the Mediterranean countries with olive oil production. Messinia, in southwestern Greece, is one of the greatest olive oil production areas in Europe. During the last decade around 1.4×10(6)tons of olive oil mill wastewater has been disposed in the rivers of Messinia and finally entered the marine ecosystem of Messiniakos gulf. The pollution from olive oil mill wastewater in the main rivers of Messinia and the oligotrophic coastal zone of Messiniakos gulf and its effects on marine organisms were evaluated, before, during and after the olive oil production period. Elevated amounts of phenols (36.2-178 mg L(-1)) and high concentrations of ammonium (7.29-18.9 mmol L(-1)) and inorganic phosphorus (0.5-7.48 mmol L(-1)) were measured in small streams where the liquid disposals from several olive oil industries were gathered before their discharge in the major rivers of Messinia. The large number of olive oil units has downgraded the riverine and marine ecosystems during the productive period and a period more than five months is needed for the recovery of the ecosystem. Statistical analysis showed that the enrichment of freshwater and the coastal zone of Messiniakos gulf in ammonia, nitrite, phenols, total organic carbon, copper, manganese and nickel was directly correlated with the wastes from olive oil. Toxicity tests using 24h LC50 Palaemonidae shrimp confirm that olive mill wastewater possesses very high toxicity in the aquatic environment.

Chemical inputs from a karstic submarine groundwater discharge (SGD) into an oligotrophic Mediterranean coastal area

The impacts of nutrient and other chemical inputs released by a submarine groundwater discharge (SGD) on the marine environment of an oligotrophic Mediterranean coastal area (Messiniakos Gulf, SE Ionian Sea) are investigated through a multidisciplinary approach. Nutrients and organic pollutants associated with the SGD are presented to study the chemical characteristics of the SGD and to investigate its effect on the marine ecosystem in comparison to freshwater discharges of the water bodies of Messinia Prefecture. Nutrient and organic pollutant fluxes were calculated from (214)Bi-based SGD estimates. An average of 22×10(3) mol of silicate per month and 8×10(3) mol of nitrate per month were released via the SGD. Nutrient concentrations at the mouth of the SGD were three times higher than in Messiniakos Gulf, and NO3(-) was the primary Dissolved Inorganic Nitrogen form discharged by SGD. Organic pollutant concentrations associated with agricultural activities were low at the SGD. The implementation of a Eutrophication Index (E.I.) showed that the water column at the SGD site corresponds to Moderate/Bad ecological quality, whereas the status switches rapidly to Good at a small distance from the SGD. Coastal areas influenced by river or sewage discharge correspond to a Moderate/Good ecological status. The BENTIX index used for the classification of the ecological quality status of the benthic macroinvertebrate communities showed that the SGD has a minor influence compared to the other freshwater discharges in Messiniakos Gulf. Though the SGD has a considerable outflow, morphology and hydrodynamics of the area favor the rapid dispersion of the upwelling water and degrades the SGD's effect even on a regional scale.

Impact of dredged urban river sediment on a Saronikos Gulf dumping site (Eastern Mediterranean): sediment toxicity, contaminant levels, and biomarkers in caged mussels

Impacts of chemical contaminants associated with dumping of dredged urban river sediments at a coastal disposal area in Saronikos Gulf (Eastern Mediterranean) were investigated through a combined approach of sediment toxicity testing and active biomonitoring with caged mussels. Chemical analyses of aliphatic hydrocarbons (AHs), polycyclic aromatic hydrocarbons (PAHs), Cu, and Zn in combination with the solid phase Microtox® test were performed on sediments. Concentrations of PAHs, AHs, Cu, and Zn as well as multiple biomarkers of contaminant exposure and/or effects were measured in caged mussels. Sediments in the disposal and neighboring area showed elevated PAHs and AHs concentrations and were characterized as toxic by the solid-phase Microtox® test during and after dumping operations. Biomarker results in the caged mussels indicated sublethal effects mainly during dumping operations, concomitantly with high concentrations of PAHs and AHs in the caged mussel tissues. Cu and Zn concentrations in sediments and caged mussels were generally not elevated except for sediments at the site in the disposal area that received the major amount of dredges. High PAHs and AHs levels as well as sublethal effects in the caged mussels were not persistent after termination of operations. The combined bioassay-biomarker approach proved useful for detecting toxicological impacts of dredged river sediment disposal in sediments and the water column. Nevertheless, further research is needed to evaluate whether sediment toxicity will have long-term effects on benthic communities of the disposal area.

Organic contamination of surface sediments in the metropolitan coastal zone of Athens, Greece: sources, degree, and ecological risk

Bottom sediments represent a crucial component of the marine environment, since they constitute a habitat, a trophic resource, and a spawning place for various organisms. Unfortunately, the sediments of urban coastal areas are deeply impacted by anthropogenic activities that degrade their quality. In the Drapetsona-Keratsini metropolitan coastal zone of Athens, current industrial and shipping activities together with the effluents from a sewage outfall, which was in operation in the past, have resulted in one of the most contaminated sedimentary environments, in terms of organic compound loads, in Mediterranean. Exceptionally high concentrations of aliphatic hydrocarbons (up to 4457 μg g⁻¹), carcinogenic PAHs (up to 7284 ng g⁻¹), and organochlorines (up to 544 ng g⁻¹ for PCBs; up to 208 ng g⁻¹ for DDTs) constitute a major threat to the marine life of the associated Saronikos Gulf.

A screening procedure for selecting the most suitable dredged material placement site at the sea. The case of the South Euboean Gulf, Greece

The selection of the best site for the placement of dredged sedimentary material (∼7,000 m(3)) from the Aliveri coastal area in the adjacent South Euboean Gulf (Greece) was accomplished through a screening procedure. The initial stage comprised the determination of physical, chemical, and biological characteristics of the dredged sediment before the commencement of any dredging operation. Grain size measurements, geochemical analyses together with the use of pollution/toxicity indices and empirical sediment quality guidelines, and the conduct of an acute toxicity test showed that the dredged material consisted of "unpolluted to slightly polluted" silty sands and sandy silts. However, the local authorities planned to place this sediment in the neighboring open sea area, i.e., the South Euboean Gulf, due to the absence of any beneficial use or alternative dumping option (i.e., dumping on public lands). Therefore, the next stage of the screening procedure, based on criteria such as the national legislation, seabed and seawater column characteristics, influence of the water mass circulation pattern on the post-placement migration of dredged sediment, impact on living resources and human activities (i.e., aquaculture and fishing), effect on significant marine sites (i.e., sites of scientific, ecological, and historical importance, navigation routes, military zones), and seafloor engineering uses, led to the evaluation of the suitability of the South Euboean Gulf as a potential dumping area. Then, the identification of the appropriate dredged material placement sites in the South Euboean Gulf was based on a cluster analysis, which tested the physicochemical resemblance of the dredged material and the surface sediments of 19 potential placement locations in the gulf. After the statistical process, only four sites situated near the north shoreline of the South Euboean Gulf were qualified as the best dredged material placement locations.

Influence of pollution history on the response of coastal bacterial and nanoeukaryote communities to crude oil and biostimulation assays

Pollution history has often been proposed to explain site-dependent bioremediation efficiencies, but this hypothesis has been poorly explored. Here, bacteria and their heterotrophic nanoflagellates (HNF) predators originating from pristine and chronically oil-polluted coastal sites were subjected to crude oil ± nutrients or emulsifier amendments. The addition of crude oil had a more visible effect on bacteria originating from the pristine site with a higher increase in the activity of given OTU and inactivation of other petroleum-sensitive bacteria, as revealed by DNA and RNA-based comparison. Such changes resulted in a delay in microbial growth and in a lower bacterial degradation of the more complex hydrocarbons. Biostimulation provoked a selection of different bacterial community assemblages and stirred metabolically active bacteria. This resulted in a clear increase of the peak of bacteria and their HNF predators and higher oil degradation, irrespective of the pollution history of the site.

Active biomonitoring in Greek coastal waters: application of the integrated biomarker response index in relation to contaminant levels in caged mussels

An integrated approach using biomarkers and contaminant levels in mussels Mytilus galloprovincialis L. was employed to assess chemical contamination in Greek coastal waters within the framework of the MYTIMED program. Biomarkers (metallothioneins, glutathione S-transferase, catalase, acetylcholinesterase and RNA:DNA ratio) have been previously described in mussels caged at 14 sites in coastal areas influenced by different types of anthropogenic activities. This study applied a biomarker index, the Integrated Biomarker Response (IBR) to summarize biomarker responses and relate stress levels to concentrations of organochlorine compounds (PCBs, DDTs), polycyclic aromatic hydrocarbons (PAHs), and metals (Cu, Ni, Fe, Zn) measured in the mussel tissues. The IBR index indicated environmental stress at sites near cities and industries and was overall related to organic contaminants, but also elevated metal concentrations at certain sites. Slightly increased IBR values at few sites away from known pollution sources were not accompanied with increased contaminant levels suggesting stress possibly caused by natural factors. Results confirmed the usefulness of integration of biological effects measurements and chemical analysis for the assessment of chemical contamination in coastal waters.

A multi-criteria approach for the dumping of dredged material in the Thermaikos Gulf, Northern Greece

A multi-criteria approach was applied for the disposal into the sea of ∼1,100,000 m(3) of sediment, dredged from a coastal area in the northeastern part of the Thermaikos Gulf. This sediment (classified as muddy) is distributed vertically into two distinct Layers (A and B) with the thickness of the surficial sedimentary unit ranging from 7 to 54 cm. Its geochemistry reveals increased Cr and Ni concentrations, which may be attributed to natural enrichment through the erosion of the adjacent igneous and metamorphic rocks. In addition, a low to moderate contamination from urban-originated heavy metals, like Cu, Pb and Zn as well as from aliphatic and polycyclic hydrocarbons was identified for the upper Layer A. However, the limited proportion (5.5%) of the polluted Layer A in the total volume of the dredged material could not affect the good quality (assessed by the Sediment Quality Guidelines) of the bulk sediment. The identification of the optimum marine dumping site was based on (a) the physicochemical similarity (detected by the application of a cluster analysis) of the dredged material with the surficial deposits of potential dumping sites in the Outer Thermaikos Gulf, and (b) the consideration, based on previous studies, of various criteria related to the disposal area such as deep-water circulation, influence on living resources, impact on economical (aquaculture, fishing, navigation), recreational (fishing) and military activities.

Biodegradation of lindane by Pleurotus ostreatus via central composite design

The degradation of lindane was studied in liquid-agitated cultures using a commercial strain of the fungus Pleurotus ostreatus as the biodegrading organism. The biodegradation was accomplished with the action of extracellular oxidative enzymes, produced by the fungus to decompose woody substrates. Enzyme activities of manganese peroxidase and laccase were measured in a liquid mineral medium. An orthogonal Central Composite Design of experiments was used to construct second-order response surfaces with the fungus growth, final pH and the lindane biodegradation as optimization parameters. The initial lindane concentration, the nitrogen content, the incubation time and the temperature were used as design factors. Optimal conditions found for all these parameters will be used for the continuation of this project aiming at the bioremediation of contaminated sites with persistent organic pollutants such as lindane.