Bioremediation of plastics in the marine environment and development of measures for mitigating plastic pollution in the Aegean Sea

Transcription

1 Bioremediation of plastics in the marine environment and development of measures for mitigating plastic pollution in the Aegean Sea S. Kiparissis, E. Yantzi, A. Perraki, E. Psillakis and N. Kalogerakis School of Environmental Engineering Technical University of Crete, Chania, Greece

2 Plastic Debris Pollution Pollution with plastics has evolved to a major ecological issue in a global scale The marine environment is severely threatened by this type of pollution and in the end of the line it is public health that is jeopardized Pollution with plastics generates a twofold problem for the marine environment: Direct impact on marine life Traumatization and death of marine animals Indirect impact on marine life Toxicant transfer to body tissue and entrance to food web

3 Direct Impact of Plastic Debris on Marine Life Cetaceans, Seals, Turtles and seabirds mistake plastic bags for prey and ingest them, or very frequently get entangled and eventually die. 1,000,000 marine mammals and seabirds die every year from plastic ingestion or entanglement Very small plastic fragments float along with plankton and are ingested by filter-feeders who are eventually deprived from necessary nutrients The fact that plastics are very durable enlarges the severity of the problem, increasing the possibility of a marine animal to encounter and ingest a drifting plastic object.

4 Indirect Impact of Plastic Debris on Marine Life Because of the nature of microplastics, hydrophobic pollutants such as polychlorinated biphenyls (PCBs) and polycyclic aromatic hydrocarbons (PAHs) can be sorbed onto plastic fragments and pellets from the surrounding seawater with concentration factors up to 10 6 The relatively high pollutant concentrations on the floating plastic pellets may also be due to the sea water micro layer where hydrophobic contaminants are known to be enriched. Along with the plastic fragments ingested by filterfeeders, sorbed toxicants are also ingested and transferred to their body tissues Bioaccumulation of persistent organic compounds (POPs) in the food chain may evolve to a serious health hazard in the long run.

5 POPs in pellets - A worldwide problem Concentration of PCBs (ng/g pellet) in beached resin pellets.

6 Confronting the problem requires: 1_ Good assessment Quantify the pollution by plastics in the marine environment Monitor the densities in the sea Monitor the densities in the beaches Explore the types of toxicants sorbed on pellets and quantify their densities Examine the extent of pollutant absorption in live tissue (biotransfer) 2_ Remediation actions 3_ Appropriate legislation based on research findings

7 Assessment of the problem in the Island of Crete Current circulation regime in the Aegean and Cretan Sea Crete constitutes a natural obstacle in the route of the currents in the Aegean as they move southwards

8 Assessment of the problem in the Island of Crete The six most heavily polluted beaches were selected as sampling sites. These sites are affected by different current systems. Sampling Sites Balos Almyrida Pachia Ammos Dionysos Cape Sidero Phalasarna

9 Assessment of the problem in the Island of Crete Sampling Sites Pachia Ammos Cape Sidero Phalasarna Almyrida Balos Dionysos

10 Assessment of the problem in the Island of Crete Categorization of plastic debris Several size class categorizations have been proposed, e.g: macrodebris (>20mm), mesodebris (2-20mm), microdebris (<2mm) [e.g. Galgani & Lecornu 2004, Thompson et al. 2009b] macroplastics (>25mm), mesoplastics (5 to <25mm), microplastics (1 to <5mm) [e.g. Lee et al. 2013] The value of 5mm is the most commonly used for defining microplastics In the present research plastic fragments and resin pellets 1-5mm were examined

11 Assessment of the problem in the Island of Crete In each sampling site: Sand was scooped down to 5cm and sieved by a 0.5mm stainless steel mesh. Large non plastic objects were removed in situ Samples were transferred to the lab in glass jars and were elaborately shorted for the complete isolation of plastics. The jars with the sorted samples are kept in a low temperature and illumination environment Sampling Procedure

12 Assessment of the problem in the Island of Crete Chemical analysis preliminary results Pellets from each site were examined for hydrophobic organic pollutants (namely PCBs and PAHs) sorbed on their surface Only brown colored, aged pellets were used for the analysis, since they are the ones most likely presenting the highest concentration of pollutants Sample preparation and analysis The internal standards used for the chemical analysis were: DBOFB for PCBs and acenaphthene-d10, chrysene-d12, phenanthrene-d10 for PAHs and Ultrasound extraction of PCBs and PAHs in 10 ml DCM and 10 ml hexane was then performed.

13 Chemical analysis preliminary results / PCBs PCBs concentrations on beached plastic pellets (consetrations in ng/g). CS= Sampling Sites. CS1:Falasarna, CS2:Balos, CS3:Almyrida, CS4:Pachia Ammos, CS5:Dyonissos, CS6:Cape Sidero

14 Chemical analysis preliminary results / PAHs PAHs concentrations on beached plastic pellets (concentrations in ng/g).

15 Chemical analysis preliminary results / PCBs = PCB sum 572 ng/g = PCB sums ng/g = PCB sum 29.4 ng/g

16 Chemical analysis preliminary results / PAHs = PAH sum 1453 ng/g = PAH sums ng/g = PAH sum <330 ng/g

17 Chemical analysis preliminary results / Ratios PAHs Phenanthrene/Anthracene >10 = petrogenic source of pollution Phenanthrene/Anthracene <10 = pyrogenic source of pollution (coal combustion) Fluoranthene/Pyrene >1 = pyrogenic source of pollution Fluoranthene/Pyrene <1 = petrogenic source of pollution Sampling site 3 (beach located in a bay of an urban area) was found to have a pyrogenic origin of PAHs contamination. Sampling sites 1,2,4 and 5 (rural areas) were found to have petrogenic PAHs, and sampling site 6 had PAHs of mixed origin.

18 Next steps Quantitative assessment of the problem of coastal pollution from plastic fragments and pellets, examining their temporal and spatial (horizontal and vertical) dispersion in the sea and the seashore Buried plastics eventually become embedded in the coastal environment. The impact of this situation on the supralittoral fauna is still unkown. Elaborate quantification of sorbed POPs on microplastics and pellets and examination of possible seasonal trends on their densities Pilot scale experiments for validation of the optimized bioaugmentation protocols in controlled marine environment Direct field testing of the bioremediation efficiency of the selected microbial strains on polymers, in the sea

19 Mitigation Actions Actions should focus firstly on assessing and handling the problem of the existing pollution and secondly on avoiding future pollution: I. Assessment of the problem Monitor with quantitative sampling the densities of plastic debris large pieces and microplastics in the water column, on the seabfloor and on the shores, for assessing the extend of the pollution Assess the degree of pollutants biotransfer. This will disclose the urgency of the problem and the urgency for appropriate measures.

20 Mitigation Actions Actions should focus firstly on assessing and handling the problem of the existing pollution and secondly on avoiding future pollution: II. Collect & remove existing debris from plastics from the water column, the seafloor and the shore Cooperate with pelagic and benthic trawlers Along with the catch, trawls bring on board large quantities of plastics they have swept from the seafloor

21 Mitigation Actions Actions should focus firstly on assessing and handling the problem of the existing pollution and secondly on avoiding future pollution: III. Develop measures to reduce the influx of plastics into the sea Control at the source: Secure the loss to the environment of disposed plastics in the landfills Designate stricter measures in handling plastic pellets in factories to reduce accidental loses Prohibit or restrict the use of plastic microgranules in cosmetics and personal care products IV. Develop new generation of plastics which are 100% biodegradable in the marine environment.