Land-based Sources Research Articles

Unraveling the land-based discharge of microplastics from sewers to oceans – A comprehensive study and risk assessment in wastewaters of Goa, India

Owing to their pervasive dispersion in the environment and their potential ramifications on both marine life and human health, microplastics (MPs) are of increasing concern. However, there is still a lack of research on the release of MPs from different land-based pathways like creeks, drainage outfalls, and conduits into coastal water systems in India. This study represents comprehensive research into the attribution of MPs in the estuarine system, specifically those emanating from wastewater sources in Panjim City, Goa, India. Urban wastewater collected from different locations in and around Panjim City exhibited values ranging from 79 ± 21 to 338 ± 7 MPs/L, with a prevalence of fibrous and black MP particles. The size range of the MPs at all sampling sites was 100–300 μm. Analysis by μ-FTIR revealed 35 distinct polymeric compositions in wastewater, with a dominance of polyacrylamide (PAM), polyvinyl chloride (PVC), and polyamide (PA). Additionally, primary and secondary MPs were studied to unravel the contributions from land-based sources. This included the quantification of MPs in ten samples from personal care products (PCPs) and twenty samples from washing machine effluents (WMEs). MPs in PCPs ranged from 1.8 to 1554 MPs/g. Microfibres and fragments were predominant in WMEs (3986 to 4898 MPs/L). This study suggests a strong relation between polymers found in wastewater effluent and those present in PCPs and WMEs. The identified polymers showed high polymer hazard indices (IV and V), posing a significant threat to the ecosystem and a potential risk to human health.

Spatial distribution of microplastics in a coastal upwelling region: Offshore dispersal from urban sources in the Humboldt Current System

In coastal waters, higher concentrations of microplastics (MPs) are generally related to densely populated and industrialized areas, but intense upwelling and offshore transport in the Eastern Boundary Upwelling Systems (EBUS) may influence this pattern. The Humboldt Current System (HCS) along the coast of northern-central Chile represents a perfect model to test whether the abundance of MP at the sea surface decreases with distance from land-based sources, e.g., river mouths, harbors, and submarine wastewater outfalls. The sea surface was sampled with a manta trawl to examine the abundance, composition, and distribution of floating MPs, and Generalized Additive Mixed Models (GAMMs) were performed to examine the relationship between MP abundance (particles km−2) and the distance to putative sources. MPs were found in all 57 net tows, with an average of ⁓120,000 MP km−2 and maximum values of ⁓1,500,000 MP km−2. The composition of MPs was dominated by fragments (>50% of the total count) and over 80% of all MPs were ≥1 mm. The combined effect of the various sources, spatially concentrated in urban areas, makes it difficult to distinguish their relative contributions, but the MP composition suggested that rivers are more important sources, followed by submarine wastewater outfalls and then harbors. A significant and steep negative relationship with the “distance to source” explained 15.2% of the variance of “MP abundance”, suggesting rapid offshore displacement within the HCS. This is the first study to report this pattern along the edges of the South Pacific Subtropical Gyre (SPSG), revealing that continuous offshore transport of microplastic from land-based sources is occurring over large scales and contributing to the accumulation of microplastics in the center of the SPSG. However, the findings additionally suggested that processes at meso- and submeso-spatial scales (driven by geographic and seasonal variables) are disrupting the general pattern.

A baseline assessment of anthropogenic macrolitter on dunes along the Bulgarian Black Sea Coast using visual census and Unmanned Aerial Systems

Beach-dune systems are among the most dynamic and sensitive elements of coastal ecosystems in the world. They represent an intersection between human activities, flora, fauna and economic interests in tourism. The Bulgarian Black Sea shoreline spans 518.7 km and comprises 131 km (25%) of the depositional coast, including beaches and 46 dune systems. Over the past three decades, heavy anthropogenic impacts have been observed, significantly altering the cleanliness of the beach-dune systems along the Bulgarian Black Sea Coast (BBSC). The research initially began as an initial assessment of macrolitter on dunes (MLD) using Unmanned Aerial Systems (UAS). However, due to concerning data obtained in the first year, it transitioned into a mid-term monitoring program conducted between 2018 and 2022. The baseline assessment is based on a visual census, UAS mapping and manual image screening procedure in a GIS environment for litter mapping in 40 areas of litter monitoring (ALMs) along the Bulgarian Coast. Throughout the five-year monitoring period, the most abundant type of MLD was “Artificial polymer materials,” accounting for 83.4% of the total number, followed by “Paper/Cardboard” (6.2%), “Glass/Ceramics” (2.8%), “Metal” (2.8%), “Processed/Worked wood” (1.83%), “Rubber” (1.29%), and “Cloth/Textile” (1.17%). Generally, 95% of the total litter amount was assessed from Land-based sources and 5% from Sea-based sources. The COVID-19 pandemic indirectly affected the cleanliness of the Bulgarian dunes due to restrictions on foreign travel, which increased the domestic tourist pressure on the Bulgarian beaches, resulting in a more significant amount of waste accumulating on the beaches and dunes. The abundance experienced an increase of 39% between 2018 and 2021. A similar upward trend (+41%) was observed in the density of macrolitter on the dunes. Based on visual census data, the average density was estimated to be 0.54 ± 0.35 items/m2. The spatial distribution of MLD is a complex combination of anthropogenic impact and wind processes that affect various eco-geomorphological elements of the beach-dune system. The embryonic dunes retained only 16% of the total items (Dav: 0.32 ± 0.12 items/m2). The highest litter density was registered on the foredunes (Dav: 0.71 ± 0.21 items/m2; 28% of total items). The backdunes contained the highest litter abundance, accounting for 55% in larger areas (Dav:0.59 items/m2). Density litter maps established that dune vegetation acted as a natural trap, retaining 40% more macrolitter compared to areas without dune plants. A Clean Dune Index (CDI) was developed to evaluate the cleanliness of Bulgarian dunes. Based on aggregated CDI data for 2018–2022, the cleanliness of the dunes along the Bulgarian Coast was categorised as “moderate” (CDIav:10.89). Dune systems near the most visited resorts were classified as “extremely dirty”, with the highest CDI values recorded at Kavatsite (27.22), Nessebar – South (25.01), Bolata (24.69), Asparuhovo - Varna (24.33) and Slanchev bryag (24.09). On the other hand, the dune systems at Ropotamo and Lipite were rated with the lowest CDI – 0.95 and 1.2. Dunes are sensitive habitats and require minimal anthropogenic impact, which requires the intensification of the use of high-resolution remote sensing methods for litter mapping. The quality of the presented data and the results obtained outline drones as a future primary tool for beach and dune surveys.

Finding equitable solutions to the land-based sources of marine plastic pollution: Sovereignty as a double-edged sword

Marine litter is a global and transboundary pollution problem. Recent attention has focused on the impact of this issue on areas beyond national jurisdiction. In many cases, marine litter is traced to a coastal State where debris have been released into the sea. Effective and legally-binding commitments at the global level to tackle land-based sources of marine pollution are rare, in large part because of the sensitive nature of territorial sovereignty. When it comes to addressing the marine plastics crisis, sovereignty is a double-edged sword. On the one hand, the international legal regime traditionally addressing marine litter, the United Nations Convention on the Law of the Sea, does not specifically respond to, and is not able to adequately address, the issue of plastics as a land-based source of marine pollution. While it contributes to social equity by recognizing the special position of developing States in terms of capacity and need for economic development, this deference to domestic decisions is not conducive to the adoption of binding and global standards. Since a large majority of plastics in the oceans originate from land, this weakness is a major concern. On the other hand, sovereignty might contribute to a solution within the regime regulating trade in waste products: unilateral actions taken in application of sovereign powers and aimed at reducing trade in plastic waste led to major multilateral actions with the potential to reduce the issue of marine plastic pollution. In recent times, the Basel Convention on the Control of Transboundary Movements of Hazardous Waste and their Disposal has indeed become an important forum to respond to the plastic waste issue, with the potential to contribute to a solution to the marine dimension of this crisis. This regime is not perfect, especially in that its complexity and reliance on enforcement at the customs level leave ample opportunities for criminal activities to flourish. Areas for improvement include addressing the legal uncertainty regarding bilateral, regional, and multilateral agreements as well as certain key definitions; strengthening the prior informed consent procedure and the Mechanism for Promoting Implementation and Compliance; and heavily investing in capacity building and technology transfer. Nonetheless, this regime provides a widely-ratified framework to decrease trade in plastic waste considered hazardous or requiring special consideration – these two categories cover most hard-to-recycle plastics. In that sense, the Basel Convention regime has the potential to reduce mismanaged plastic waste leaking into the oceans and to contribute to social equity between States–if not domestically–by reducing the practice of wealthy countries using developing States as dumping grounds under the pretense of mutually beneficial trade in waste products.

Spatiotemporal distribution, source analysis and ecological risk assessment of polychlorinated biphenyls (PCBs) in the Bohai Bay, China

As a class of persistent organic pollutants (POPs), the spatial and temporal distribution of polychlorinated biphenyls (PCBs) in seawater is important for environmental assessment. Surface water samples were collected from 35 stations during summer and 36 stations during autumn of 2020 in the Bohai Bay. The concentration, composition, distribution and sources of PCBs were analyzed to assess the ecological impact of PCBs. The average concentration of ∑18PCBs was 124.6 ng/L (range of 28.1–445.5 ng/L) in summer and 122.8 ng/L (range of 21.0–581.4 ng/L) in autumn. PCBs in surface seawater of the Bohai Bay showed high near-shore and low far-shore characteristics, indicating the serious influence of land-based sources such as port activities and river inputs. Proportion analysis showed that Tetra-PCBs and Penta-PCBs were the major constituents in most stations. It was assessed as moderate and high risk (MRQ > 0.1) by mixture risk quotient (MRQ) and concentration addition (CA) model in surface seawater of the Bohai Bay. Principal component analysis (PCA) was used to explain the sources of PCBs in the Bohai Bay. PCBs in the Bohai Bay may come from commercial PCBs and their incineration products, municipal landfills, wood and coal combustion, and industrial activities, etc.

Polychlorinated biphenyl and polybrominated diphenyl ether profiles vary with feeding ecology and marine rearing distribution among 10 Chinook salmon (Oncorhynchus tshawytscha) stocks in the North Pacific Ocean

Chinook salmon (Oncorhynchus tshawytscha) along the west coast of North America have experienced significant declines in abundance and body size over recent decades due to several anthropogenic stressors. Understanding the reasons underlying the relatively high levels of persistent organic pollutants (POPs) in Chinook stocks is an important need, as it informs recovery planning for this foundation species, as well for the Chinook-dependent Resident killer whales (Orcinus orca, RKW) of British Columbia (Canada) and Washington State (USA). We evaluated the influence of stock-related differences in feeding ecology, using stable isotopes, and marine rearing ground on the concentrations and patterns of polychlorinated biphenyls (PCBs) and polybrominated diphenyl ethers (PBDEs) in Chinook salmon. A principal components analysis (PCA) revealed a clear divergence of PCB and PBDE congener patterns between Chinook with a nearshore rearing distribution (‘shelf resident’) versus a more offshore distribution. Shelf resident Chinook had 12-fold higher PCB concentrations and 46-fold higher PBDE concentrations relative to offshore stocks. Shelf resident Chinook had PCB and PBDE profiles that were heavier and dominated by more bioaccumulative congeners, respectively. The higher δ13C and δ15N in shelf resident Chinook compared to the offshore rearing stocks, and their different marine distributions explain the large divergence in contaminant levels and profiles, with shelf resident stocks being heavily influenced by land-based sources of industrial contamination. Results provide compelling new insight into the drivers of contaminant accumulation in Chinook salmon, raise important questions about the consequences for their health, and explain a major pathway to the heavily POP-contaminated Resident killer whales that consume them.

Assessment of beach macrolitter using unmanned aerial systems: A study along the Bulgarian Black Sea Coast

Over the years, the Black Sea has been impacted by the issue of marine litter, which poses ecological and health threats. A mid-term monitoring program initiated in 2018 assessed the abundance, density, and composition of beach litter (BL) on 40 frequently visited beaches. From 2018 to 2022, there was a significant increase in average abundance, rising by 261 %. Artificial polymer materials accounted for the majority (84 %) of the litter. Land-based sources dominated 77 % of the litter. The Clean Coast Index (CCI) categorized the beaches as “moderate” with an average value of 8.9 for the period between 2018 and 2022. However, the years 2021 and 2022, during the COVID-19 epidemic, were identified as the “dirtiest period” with 11 beaches classified as “extremely dirty” due to high domestic tourist pressure. The study demonstrates a successful combination of standard in situ visual assessment supported by unmanned aerial systems for beach litter surveys.

BIODEGRADATION OF WASTED BIOPLASTICS

Bioplastic is plastic made from renewable biological material, usually plants, bio-waste or microorganisms, rather than petroleum or natural gas. Most bioplastics are environmentally friendly compared to plastics that are made from fossil fuels. But this is not always the case - a lot depends on how bioplastic is produced and disposed of. The bioplastics industry is young—accounting for only 1% of global plastics production in 2019. Standardization of raw material sources, types of plastic, or labeling of what is biodegradable or compostable is poorly developed. This often confuses consumers because not everything made from plants is biodegradable. However, growing awareness of the dangers of overuse of plastics and increased government regulation of plastic waste have led to a surge of interest and investment in bioplastics, an industry expected to grow 10-14% in the next few years. It is possible that this will partially help solve one of the most serious environmental problems in the world: plastic pollution. Marine plastic pollution is a growing global problem. The most striking example is the Great Pacific Garbage Patch. According to the EPA (U.S. Environmental Protection Agency), of the approximately 36 million tons of plastic produced annually in the United States, less than 1% is recycled. Globally, only about 9% of plastic waste is recycled. About 11 million tons of plastic waste are dumped into the world's oceans every year. Even more comes from land-based sources, where plastic slowly breaks down into smaller and smaller particles. According to some estimates, there are up to 51 trillion microplastic particles floating in our oceans. Scientists estimate that the average adult ingests approximately 883 microplastic particles every day, which accumulate in our body tissues. Ingestion of plastic by marine and terrestrial animals can have extremely adverse effects on their health, including death.

Sedimentary records of contaminant inputs in Frobisher Bay, Nunavut

Contaminants, such as polychlorinated biphenyls (PCBs), polycyclic aromatic hydrocarbons (PAHs), heavy metals, and per and polyfluoroalkyl substances (PFASs), primarily reach the Arctic through long-range atmospheric and oceanic transport. However, local sources within the Arctic also contribute to the levels observed in the environment, including legacy sources and new sources that arise from activities associated with increasing commercial and industrial development. The City of Iqaluit in Frobisher Bay, Nunavut (Canada), has seen rapid population growth and associated development during recent decades yet remains a site of interest for ocean protection, where Inuit continue to harvest country food. In the present study, seven dated marine sediment cores collected in Koojesse Inlet near Iqaluit, and from sites in inner and outer Frobisher Bay, respectively, were analyzed for total mercury (THg), major and trace elements, PAHs, PCBs, and PFASs. The sedimentary record in Koojesse Inlet shows a period of Aroclor 1260-like PCB input concurrent with military site presence in the 1950–60s, followed by decades of input of pyrogenic PAHs, averaging about ten times background levels. Near-surface sediments in Koojesse Inlet also show evidence of transient local-source inputs of THg and PFASs, and recycling or continued slow release of PCBs from legacy land-based sources. Differences in PFAS congener composition clearly distinguish the local sources from long-range transport. Outside Koojesse Inlet but still in inner Frobisher Bay, 9.2 km from Iqaluit, sediments showed evidence of both local source (PCB) and long-range transport. In outer Frobisher Bay, an up-core increase in THg and PFASs in sediments may be explained by ongoing inputs of these contaminants from long-range transport. The context for ocean protection and country food harvesting in this region of the Arctic clearly involves both local sources and long-range transport, with past human activities leaving a long legacy insofar as levels of persistent organic pollutants are concerned.

Chemical Oxygen Demand(COD) Composition and Contribution in Typical Waters of Baiyangdian Lake

Chemical oxygen demand (COD) is an important index used to assess organic oxygen consumption pollution. To explore COD composition in the natural water in Baiyangdian Lake, the main composition, source, and influencing factors of oxygen-consuming organic substances in the water body were revealed through physical continuous classification, three-dimensional fluorescence, and other methods. The results showed that the COD of the two waters was affected by dissolved organic substances (protein-like and humus-like organic matters) with size of less than 220 nm (59%-93%), and inorganic substances had little effect on COD. The source of organic matter in overlying water was primarily affected by endophytic vegetation decomposition, sediment release (the release flux of TOC was in the range of 1.55-2.28 mg·(m2·d)-1), and other endogenous sources (biological index>0.8), as well as by land-based sources such as reed platform and artificial pollution (1.4<fluorescence index<1.9). The sediment organic matter was primarily affected by terrestrial sources like reeds. Furthermore, COD in Baiyangdian Lake was primarily controlled by refractory dissolved organic matter (RDOC). In a natural water body, RDOC could undergo a long-term degradation reaction, and the potassium dichromate method would rapidly oxidize most RDOC within a short time, leading to the overestimation of the organic oxygen consumption pollution in Baiyangdian Lake.

Source, transport, and fate of perfluoroalkyl acids (PFAAs) in turbid bay environments: Significant roles of suspended sediment and water column stratification.

The coastal area was the major region receiving pollution from land-based sources into the sea. Perfluoroalkyl acids (PFAAs) in famous bays had aroused wide concern, but the importance of underdeveloped or small bays with notable levels of PFAAs were often neglected. Moreover, the roles of suspended sediment (SPS) and water column stratification on PFAA behaviors were unclear. In this study, PFAAs distribution in multiphase-multilayer in four underdeveloped bays (two urban bays and two island bays) were investigated. The urban bays not only had higher PFAA contamination but also posed a greater threat of short-chain PFAAs in water-SPS-sediment system than the island bays. The major source of PFAAs in water and SPS was domestic sewage in urban bays and was rainfall-runoff in island bays. Water column stratification with higher PFAA partition in water-SPS system in the surface layer than in the bottom layer was only found in the urban bays due to the higher human activity intensity. These provided new perspectives for managing emerging contaminants and establishing water quality criteria in the turbid coastal environment. The key role of SPS as a carrier offered possibilities to accurately differentiate the effects of dissolved and particulate PFAAs on bioavailability.

Macrolitter and mesolitter in the Thames Estuary: A temporal litter assessment and brand audit of submerged and riverbed debris

Macroplastic is a growing concern for marine environments with estuaries providing a major pathway for pollution from land-based sources to the sea. In the Thames Estuary, plastic was abundant floating below the surface and on the riverbed, with an average catch per unit effort of 0.57 ± 0.42 and 2.75 ± 2.44 item per minute respectively. Whilst the abundance of litter differed between midwater and benthic zones, the types of products recovered did not. These were identified through visual examination and use of a unique citizen science engagement protocol, allowing for the item age, brand and countries of origin to be established. The majority of litter from the present study (n = 1335) was packaging (40%), some of which was over 30-years old and may have originated from landfill run off. Also abundant was sewage-related debris, the inputs of which was related to heavy or prolonged rainfall. Peaks in this material were recorded in September 2020 following the greatest volume of rain recorded in a single day and in June 2019 after the longest period of continuous rainfall. The Covid-19 pandemic did not influence the abundance or diversity of plastic recovered between December 2018 and September 2020. The durability of plastic ensures it has high potential for harm through entanglement, deoxygenation of sediment and ingestion. The retention in the environment also increases opportunities to fragment into micro- or nanoplastics and, therefore, it is important to monitor plastics at both a macro- and micro-scale.

Characterizing microplastics in urban runoff: A multi-land use assessment with a focus on 1–125 μm size particles

Urban areas play a significant role in generating microplastics (MPs) through increased vehicular and human activities, making urban runoff a key source of MP pollution in receiving waterways. The composition of MPs is anticipated to vary with land use; hence, identifying the hotspots of contamination within urban areas is imperative for the targeted interventions to reduce MPs at their sources. This study collected one-liter stormwater runoffs from three different land uses as sheet flow during two storm events to quantify the MPs and identify the polymers transported from land-based sources. The analytical method included a combination of Fourier transform infrared spectrometer, Raman microscope, and Nile red staining techniques. This study analyzed the broad spectrum of MPs, i.e., 1 μm–5 mm, and tire wear and bitumen particles, considered the two major research gaps in stormwater studies. The MP concentrations were 67.7 ± 11.3 pL‐1in commercial, 23 ± 10.3 pL‐1 in residential, and 168.7 ± 37.1 pL‐1in highways. The trend of MP concentrations followed an order of highway > commercial > residential with an exclusive presence of polymethylmethacrylate and ethylene-vinyl acetate in highways; cellophane, methylcellulose, polystyrene, polyamide, and polytetrafluorethylene in commercial; and high-density polyethylene in residential areas. The dominant MP morphology consisted of fragments, accounting for 89 % of the identified MPs, followed by 10 % fibers and 1 % films. This study observed a prevalence of MPs sizes <125 μm constituting 49 % of the total composition. These findings underscore the vital role of land use patterns in shaping MP abundance and reinforce the urgency of implementing effective management strategies to mitigate MP pollution in stormwater runoff.

Spatiotemporal Nutrient Patterns, Stoichiometry, and Eutrophication Assessment in the Tieshan Bay Coastal Water, China

Land-source inputs into coastal water have increased remarkably in recent years, resulting in the deterioration of water quality, eutrophication, and algae blooms. However, we have limited understanding of spatiotemporal nutrient patterns, stoichiometry, and eutrophication assessment in Tieshan Bay coastal water at present. To investigate the rapid development of the coastal areas in Tieshan Bay in the South China Sea, nutrients and other physicochemical parameters were observed in Tieshan Bay during the normal season (April), wet season (July), and dry season (October) in 2021. The results showed that the average concentrations of dissolved inorganic nitrogen (DIN), dissolved inorganic phosphorus (DIP), and chemical oxygen demand (COD) in Tieshan Bay are 0.071 ± 0.115 mg/L, 0.008 ± 0.013 mg/L, and 0.71 ± 0.219 mg/L, respectively. DIN/DIP ratio ranges from 9.1–69.3, with an average value of 19.9 ± 19.2, which exceeds the Redfield value, behaving P limitations. In addition, the mean eutrophication index (EI) was low in Tieshan Bay, with an average value of 0.5 ± 1.5. Moreover, the hotspot coastal water with high DIN, DIP, and COD concentrations was located in the upper half of Tieshan Bay in all seasons. In addition to the DIN, DIP, and COD contributions to EI, the average contribution rates of DIN, DIP, and COD are 26.6%, 8.8%, and 64.6%, respectively, which leads to the largest contribution of COD to EI. Furthermore, the average comprehensive index (CI) of organic pollution in Tieshan Bay surface seawater ranged from −1 to 5.6. The seawater near Hepu in S8 station has organic pollution in wet and dry seasons, and Tieshan Bay’s middle region also has slight organic pollution. Additionally, the DIN, DIP, and COD had significant relationships with salinity (p &lt; 0.05), suggesting that coastal water quality is affected by land-based sources input. To achieve the seawater quality target and mitigate regional eutrophication, it is critical to implement land-based source management across the river-bay-coastal water continuum.

Modelled and observed plastic pollution on remote Scottish beaches: The importance of local marine sources

Beach-cleans conducted on the west coast of Scotland investigated the distribution of land- and marine-sourced litter and compared these with a particle tracking model representing the presumed principal land-based source. Modelled particles dispersed widely, even reaching the remote northwest coast, with ‘hotspots’ and ‘coldspots’ on windward and leeward coasts respectively. In beach sampling, however, land-sourced litter represented only 19% of items by count and 8% by weight, while marine-sourced litter represented 46% by count and 62% by weight. The source of the remainder could not be identified. Windward coasts had an average count of 1859 litter items per 100 m, and weight of 14,862 g per 100 m. Leeward coasts had an average count of 32 litter items per 100 m and weight of 738 g per 100 m. Field observations and model predictions were consistent in many respects for land-sourced litter, however marine-sourced litter is dominant on many coastlines.

Application of the Principle of Prevention to land-based sources of marine pollution: an International Law approach

Despite being a major environmental issue, marine pollution of onshore origin has not been addressed through a clear and coherent international legal framework. The aim of this article is, therefore, to reconduct such fragmented framework to a single international rule, with the potential of effectively facing the issue. This led the investigation to focus on the Principle of Prevention, which, despite being a cornerstone of international environmental law, has remained quite evanescent as to its normative content. With this in mind, the article attempts to reconstruct the actual content of the rule with specific regard to the issue at stake. In order to do so, it has been essential to identify the standard of “diligence” States are held to in such regard and to verify how such “due diligence” interacts with the primary rule and contributes to fill it with normative content. The result is a single legal rule with a renewed potential, especially in terms of enforcement opportunities.

Modelling the relative risk of plastic pollution to wildlife when data are scarce: an applied approach in the Mekong and Ganges river basins

Plastic pollution of aquatic ecosystems is a growing environmental problem. Most plastic pollution originates from land-based sources and is transported via rivers, where plastic densities can exceed those at sea. Rivers in southeast Asia are regularly identified among those transporting the greatest plastic loads globally, yet are among the least studied major river systems. This is particularly concerning since they provide habitat for commercially, culturally and ecologically important species. We present a four-step risk framework to assess the relative risk to wildlife at different sections of a river, particularly where data may be sparse. We apply this method to a case study in the Ganges and Mekong rivers. The first step is to estimate litter density and abandoned fishing gear (ALDFG) to determine the relative level of pressure from ingestion or entanglement. Step two uses a risk assessment to determine the likelihood of a species interacting with a given item, and the further likelihood of a negative outcome of that encounter. Step three determines the overlap of the habitat of the species with the litter present in the environment, and the final step integrates all of these factors to present an overall relative risk to migratory species within each watershed. In the Ganges and Mekong rivers, entanglement represents the highest risk to species. The methods presented here estimate the relative risk to vertebrate fauna from litter interactions in rivers where empirical data are not available, aiming to determine (i) where in each river do we expect to find the most plastic and ALDFG and (ii) whether species suspected to be threatened by plastic pollution overlap with these predicted high-risk regions. This approach will aid decision-makers to make informed precautionary assessments bridging data gaps about relative plastic loads and associated risks in aquatic systems, until empirical data becomes available.

Sources of sedimentary organic matter in Arctic fjords: Evidence from lipid molecular markers

The identification of the origin of organic matter in Arctic fjord systems is especially challenging due to complex and highly variable environmental settings, which are impacted by ongoing rapid climate changes. In this study we use a multiproxy approach based on various lipid biomarkers to investigate the provenance of organic matter deposited in surface sediments in the four high-Arctic fjords located in the western part of Spitsbergen (Hornsund, Adventfjorden, Kongsfjorden, and Raudfjorden). This work focuses on the analyses of several classes of lipid biomarkers such as n-alkanes, saturated cyclic hydrocarbons (hopanes, steranes), highly branched isoprenoid (IP25 – ice proxy), alkenones and polar steroids, including sterols and stanols. The findings of this research indicate the occurrence of sedimentary organic matter derived from multiple marine and land-based sources in the studied fjords. The analysis of biomarkers reveals pronounced differences between fjords located in southern and northern parts of western Spitsbergen with regard to contributions of sedimentary organic matter derived from biogenic sources (phytoplankton, animal-derived material as well as terrestrial vascular plants), relative abundances of specific phytoplankton genera (diatoms vs. dinoflagellates), and intensity of bio-advection (Emiliania huxleyi) related to inflows of warm Atlantic Water. The uncommon n-alkane profiles, especially in the short-chain range, reported for investigated sediments are likely to reflect probable contributions related to ancient organic matter and/or microbial sources/activities. To our knowledge, this is the first such comprehensive research on the origin of organic matter deposited in surface sediments from the western Spitsbergen fjords, based on lipid molecular biomarkers.

Microplastics in surface coastal waters around Plymouth, UK, and the contribution of boating and shipping activities

Microplastics determined in surface water trawls from coastal waters around Plymouth, southwest England, ranged from 0.26 to 0.68 n m−3, with a decrease evident from the lower estuaries of the Tamar and Plym to areas in Plymouth Sound more remote from urbanisation. Microplastics were dominated by fibres of rayon and polypropylene and fragments of polyester and epoxy resins, with fragment concentration demonstrating a significant and positive linear relationship with concentration of floating and suspended matter retrieved by the trawls. Observations are attributed to the suspension of land-based (e.g., treated municipal waste) sources of textile fibres, and the flotation of land-based and in situ emissions of paints and resins from boating and shipping activities. The implied decoupling of microplastic transport based on shape and origin merits further investigation while the more general determination of floating and suspended matter concentration in microplastic studies is recommended.

Indonesian policy and researches toward 70% reduction of marine plastic pollution by 2025

Marine plastic litter has become an emerging pollution issue in Indonesia. In this review, we examined policies related to plastic litter and their impact on reducing plastic litter in Indonesian seas and analyzed the progress in marine plastic research to contribute to the policy. Then, synthesized gaps to improve policy and possible scientific contributions to reduce marine plastic pollution. Our review showed that Indonesia's policy on reducing marine plastic litter pollution was largely focused on land-based sources, lack of sea-based leakage, and limited community behavior change in plastic use. Most research was done in the central region of Indonesia where a hotspot of marine plastic pollution occurred, and understudied in western and eastern regions. The national policy to reduce 70% of marine plastic litter entering the Indonesian seas by 2025 requires an extended period. The active role of local governments, improvement of solid waste management information system, and establishment of a marine plastic research agenda are among the most crucial for achieving national targets.