This study investigated the role of a municipal wastewater treatment plant (WWTP) effluent and an abandoned coastal landfill as pathways for microplastics (MPs) input into the marine environment. MPs were first analyzed in raw sewage influent, sludge and effluent samples, and their fate was studied along a distance gradient from the WWTP in three matrices: surface water, sediments and wild mussels. All suspected MPs were characterized according to their polymer nature using micro-Raman spectroscopy. The investigated WWTP had an estimated daily discharge of 227 million MPs. MPs were found in all matrices with a decreasing abundance from the effluent. Strong MPs abundances (higher than those found near the WWTP effluent) were observed in the vicinity of the coastal landfill suggesting its importance as a MPs entry route into the marine coastal environment. Our study supports the idea that blue mussels are a promising sentinel species for MPs (<200 μm).
Pollution and Marine Debris
Phosphate mining activities on Christmas Island began in the late 1800's providing a unique, long-term case study in which to assess the impacts of mining on coral reef development. Watershed modelling was used to identify potential “hotspots” of mining runoff on to adjacent reefs. Pollution hotspots were also confirmed by analysis of reef sediment. Phosphate rich mining runoff flowed from local watersheds onto nearshore coral reefs with levels of up to 54,000 mg/kg of total phosphate recorded in reef sediment at the Dryers reef site adjacent to the main phosphate storage facility. Using this combination of watershed modelling and in-situ sediment contamination data we identified six coral reef sites along an environmental impact gradient. In-situ benthic transects were paired with a new rubble-encruster method enabling the analysis to combine large scale transect information alongside fine-scale data on epibenthic and encruster assemblages. Results demonstrate that phosphate rich sediment loading negatively impacted coral reef building communities, in particular, branching corals and calcareous encrusting organisms, critical to the future survival of coral reef ecosystems. These findings highlight the importance of curtailing runoff and pollution from catchment based mining activities and protecting reefs for the future.
Marine plastic pollution is heavily driven by escaped plastic waste from land. Effectively reducing flows of plastic pollution into the oceans requires incentivizing efficient disposal decisions, discouraging production and consumption of products with low recyclability and reuse potential, and encouraging lower-impact, easily recyclable product and packaging designs. We examine the economic literature on waste management and integrated environmental policy to assess how particular policies target these individual pathways and can efficiently reduce flows of plastics into waterways. These policies include production/retail bans and standards, extended producer responsibility, price-based policies such as advance disposal fees and two-part instruments, and interventions grounded in behavioral economics and psychology. We also consider the applicability of these policies in coastal developing nations that often rely upon the informal sector for waste management services. We conclude by identifying important issues for future research.
The Deepwater Horizon (DWH) oil spill may be indicative of future large, deep spills that may occur in the coming decades. Given that future deepwater spills are possible, critical considerations include (1) establishing baselines for oceanic marine mammal and populations in at-risk areas, (2) understanding the implications of response choices for oceanic marine mammals, (3) designing studies with adequate coverage for post-spill monitoring, and (4) identifying effective strategies for oceanic marine mammal restoration. In this chapter, we consider these four stages in the context of a series of hypothetical oil spill scenarios, identifying ways that lessons learned from the DWH oil spill and prior events can be applied to future disasters.
The rapid environmental changes in Australia prompt a more thorough investigation of the influence of transportation, local emissions, and optical–chemical properties on aerosol production across the region. A month-long intensive measurement campaign was conducted during spring 2016 at Mission Beach, a remote coastal site west of the Great Barrier Reef (GBR) on the north-east coast of Australia. One aerosol pollution episode was investigated in early October. This event was governed by meteorological conditions and characterized by the increase in black carbon (BC) mass concentration (averaged value of 0.35 ± 0.20 μg m−3). Under the influence of the continental transportation, a new layer of nucleation-mode aerosols with an initial size diameter of 20 nm was observed and aerosol number concentrations reached the peak of 6733 cm−3 at a diameter of 29 nm. The averaged aerosol extinction coefficient at the height of 2 km was 150 Mm−1, with a small depolarized ratio (3.5–5%). Simultaneously, the boundary layer height presented a fall–rise trend in the presence of these enhanced aerosol concentrations and became stable in a later stage of the episode. We did not observe clear boundary layer height diurnal variations from the LiDAR observations or from the Weather Research and Forecasting (WRF) model outputs, except in an earlier stage of the aerosol episode for the former. Although the sea breeze may have been responsible for these particles, on the balance of available data, we suggest that the aerosol properties at the GBR surface during this period are more likely influenced by regional transportation of continental sources, including biomass-burning aerosols.
We present a study of small microplastic particles (S-MPPs) in the sediments of mangrove ecosystem of Khor-e- Khoran, a Ramsar site in Iran. The spatial distribution of S-MPPs (<1 mm) in mangrove surface sediments were investigated, which provided new insights into the detection and composition of S-MPPs in the study area. S-MPPs were extracted via the air-induced overflow (AIO) extraction procedure, and then they were counted and categorized according to the particle shape, color and size. The mean number of S-MPPs at the five sampling sites ranged from 19.5 to 34.5 particles per kg dry sediment in Bandar Gelkan and Bandar Lengeh, respectively. In general, microfibres followed by fragments were the most common type of S-MPPs isolated in each site (>56% and ~35%, respectively). Sewage discharge is probably the main source of extracted fibres in almost all the sites. The observed S-MPPs were classified into two size groups (10–300 μm and 300–1000 μm). The majority of S-MPPs fell into the smallest size group which accounted for 70–97% of the total S-MPPs. Fourier transform infrared (FTIR) analysis of some subsamples showed that polyethylene (PE) was the most common recovered polymer. Some non-plastic particles were also isolated from plastic-like particles of suspected S-MPPs in the mangrove sediments using a Scanning Electron Microscope (FE-SEM). This study provided the first evidence of S-MPPs contamination in the mangroves of the Iranian coast of the Persian Gulf. Long-term studies are required to understand, monitor and prevent further microplastics pollution in the region.
Plastic pollution is an omnipresent problem that threatens marine animals through ingestion and entanglement. Marine mammals are no exception to this rule but their interaction with plastic remains understudied in the Mediterranean Sea. Here we highlight this problem by analyzing the stomach contents of 34 individuals from seven odontocete species stranded in Greece. Macroplastic (>5 mm) were found in the stomachs of nine individuals from four species (harbour porpoise Phocoena phocoena, Risso's dolphin Grampus griseus, Cuvier's beaked whale Ziphius cavirostrisand sperm whale Physeter macrocephalus) with the highest frequency of occurrence in sperm whales (60%). Gastric blockage from plastic was presumably lethal in three cases, with plastic bags being the most common finding (46%). Plastic ingestion is of particular conservation concern for the endangered Mediterranean sperm whales. A regular examination of stranded cetaceans with a standardised protocol is critical for allowing spatiotemporal comparisons within and across species.
The role of rivers as a major transport pathway for all sizes of plastic debris into the ocean is widely recognized. Global modelling studies ranked the Changjiang River as the largest contributor of plastic waste to the marine environment, but these estimates were based on insufficient empirical data. To better understand the role of rivers in delivering terrestrial plastic debris to the ocean, the spatial and temporal patterns of microplastics (MP) in the Changjiang Estuary (CE) and the East China Sea (ECS) were studied based on surface water samples in February, May, and July 2017. A total of 3225 MP (60–5000 μm) were identified by Fourier-transform infrared (FTIR) spectrometry. MP abundance in July was higher than in February and May due to higher river discharge. Density stratification in CE significantly influenced the surface MP abundances. A temporal accumulation zone within the river-sea interface for plastics was indicated by stations with apparently higher abundances in the river plume. Fibers were the most common MP (>80%) over three months. Small MP (<1000 μm) composed 75.0% of the total plastics on average. The average mass of MP was 0.000033 g/particle, which was two orders of magnitude lower than the empirical mass in literature. Without considering tidal effects, we estimate 16–20 trillion MP particles, weighing 537.6–905.9 tons, entered the sea through the surface water layer of the Changjiang River in 2017. These findings of this study provide reliable information on MP waste in a large river, which should be considered in further studies for estimating the riverine plastic loads.
The accumulation of plastic wastes in the marine environment represents a steadily increasing global environmental threat. The replacement of conventional plastics with bio-based biodegradable materials may contribute to alleviating the problem in the long run. This work studies the disintegration behaviour of three bio-based plastic materials, namely Polyhydroxybutyrate (PHB), Polybutylene sebacate (PBSe), Polybutylene sebacate-co-terephthalate (PBSeT), in three different coastal zone marine environments under natural conditions. The three studied environments were: 1) the seashore zone which is periodically covered by the seawater due to waves or tide, called eulittoral or intertidal zone; 2) the water column zone of small depth (about 10 m), called pelagic zone; and 3) the interface zone between the water column and the seabed sediment at small depth (about 20 m), called sublittoral or benthic zone. The experiments took place in the Aegean Sea at the SW coast of Salamis Island. The results showed that disintegration, as an indicative measure of biodegradation, occurs in all three tested environments, even though the rate depends on the material, the habitat, and the prevailing during the testing period environmental conditions. The degrees of disintegration of all materials in the three environments exhibited significant differences: Benthic > Intertidal > Pelagic. The observed disintegration can be attributed to biodegradation since the negative reference Low-density Polyethylene (LLDPE) material did not disintegrate.
Plastic pollution in the marine environment is a pervasive and increasing threat to global biodiversity. Prioritising management actions that target marine plastic pollution require spatial information on the dispersal and settlement of plastics from both local and external sources. However, there is a mismatch between the scale of most plastic dispersal studies (regional, national and global) and the scale relevant to management action (local). We use a fine-resolution hydrodynamic model to predict the potential exposure of coastal habitats and species (mangroves, coral reefs and marine turtles) to plastic pollution at the local scale of a management region (the 1,700 km2 Whitsunday Islands, Queensland, Australia). We assessed the potential exposure of mangroves, coral reefs and marine turtles to plastics during the two dominant wind conditions of the region; the trade wind and monsoon wind seasons. We found that in the trade wind season (April to September) all habitats and species had lower exposure than during the monsoon wind season (October to March). In both wind seasons we found a small proportion of coral reef habitat and large area of turtle habitat were in high potential exposure categories. Unlike coral reefs or marine turtles, mangroves had consistent hotspots of high exposure across wind seasons. Local scale management requires data at fine resolution to capture the variability that occurs at this scale. The outputs of our study can inform the development of conservation resources and local scale management action.