Flows from Economy to Environment

1. Outcome

This Circular provides guidance on compiling accounts for flows from the economy to the marine and coastal environment, encompassing pollution, residuals, and physical pressures. Upon completing this Circular, readers will understand:

• Why tracking economy-to-environment flows matters for ocean policy and management
• How to compile physical flow accounts for emissions, waste, and residuals that reach marine waters
• How to attribute land-based pollution to coastal and marine areas using drainage basin allocation
• How to measure physical pressures such as underwater noise and habitat disturbance
• How to link residual flow accounts to pressure indicators and ecosystem condition accounts

The guidance enables compilation of residual flow accounts consistent with the System of Environmental-Economic Accounting Central Framework (SEEA CF)^[1] and integrates with the broader Ocean Accounts framework described in TG-0.1 General Introduction. This Circular builds on the physical flow accounting framework established in TG-3.1 Physical Flow Accounts and the economic activity classifications detailed in TG-3.3 Economic Activity Relevant to the Ocean. The accounts compiled using this guidance support derivation of indicators for environmental pressure assessment (TG-2.7 Environmental Pressures) and ecosystem degradation monitoring (TG-2.8 Ecosystem Degradation).

2. Requirements

This Circular requires familiarity with:

• TG-0.1 General Introduction to Ocean Accounts -- for the conceptual framework and key components of Ocean Accounts
• TG-3.1 Physical Flow Accounts -- for the general framework of physical supply and use tables and residual flow accounting
• TG-3.3 Economic Activity Relevant to the Ocean -- for industry classifications and economic sector definitions relevant to ocean accounting

3. Guidance Material

3.0 Decision Use-Case Framing

Residual flows from the economy to the marine environment represent critical pressures that affect ecosystem health, fisheries productivity, coastal protection capacity, and human well-being. Policy-makers require systematic information on these flows to answer questions such as:

• Which economic sectors contribute most to nutrient loading in coastal waters, and how can agricultural and aquaculture practices be adjusted to reduce eutrophication?
• What is the trajectory of plastic waste reaching the ocean from land-based sources, and are waste management interventions reducing marine litter?
• How do ship emissions contribute to ocean acidification and coastal air quality, and what would be the impact of stricter fuel standards?
• Which coastal areas face the greatest pollution pressure from multiple sources, and where should marine spatial planning prioritize environmental protection?

Ocean accounts for residual flows provide the empirical foundation for addressing these questions. By organizing data on emissions, waste, and physical disturbances within a coherent accounting framework, compilers enable systematic tracking of pressures over time, consistent attribution to economic sources, and integration with ecosystem condition accounts to assess environmental outcomes. This supports evidence-based policy design, monitoring of international commitments (including SDG Target 14.1 on marine pollution), and evaluation of intervention effectiveness.

3.1 Conceptual Framework for Residual Flows

The marine environment receives substantial flows of residuals from economic activity, including pollutants discharged to water, solid waste and marine litter, atmospheric emissions that deposit in ocean waters, and physical disturbances such as underwater noise and light pollution. These flows constitute pressures on marine ecosystems that can affect ecosystem condition and the capacity of marine ecosystems to deliver services. Accounting for these flows enables assessment of the environmental impact of economic activity and supports policy responses aimed at reducing pressures on the marine environment.

The accounting framework for residual flows draws on the physical supply and use table (PSUT) structure established in the SEEA Central Framework^[2]. Residuals are defined as flows of solid, liquid, and gaseous materials, and energy, that are discarded, discharged, or emitted by establishments and households through processes of production, consumption, or accumulation^[3]. For ocean accounting purposes, the focus is on residual flows that reach marine and coastal waters either directly or through intermediary pathways.

Residual flows correspond to the 'Pressures' component in the widely used Drivers-Pressures-State-Impact-Response (DPSIR) framework for environmental assessment. Economic activities (Drivers) generate residual flows (Pressures) that affect marine ecosystem condition (State), resulting in consequences for ecosystem services and human welfare (Impact), which in turn prompt policy actions (Response). The accounting framework presented in this Circular provides a systematic, quantitative basis for measuring the Pressures component and linking it to the economic Drivers through industry attribution.

3.2 Pollution and Emissions

Marine pollution encompasses substances released to water resources and the atmosphere that subsequently affect ocean waters. The SEEA framework distinguishes between emissions to air, emissions to water, and emissions to soil, each of which can contribute to marine environmental degradation^[4].

3.2.1 Emissions to water

Emissions to water are substances released to water resources by establishments and households as a result of production, consumption, and accumulation processes^[5]. These emissions can reach marine waters through several pathways:

1. Direct discharges -- substances released directly to marine or coastal waters from industrial facilities, vessels, or coastal infrastructure
2. Indirect discharges via sewerage -- substances released to sewerage systems that subsequently discharge to marine waters, either treated or untreated
3. Non-point source emissions -- diffuse releases including urban runoff, agricultural runoff carrying fertilizers and pesticides, and leaching from contaminated sites

The SEEA water emissions account records the quantity of substances added to water by establishments and households during an accounting period, expressed in mass units (kilograms or tonnes depending on the substance)^[6]. Key substance categories for marine water quality include:

• Nutrients -- nitrogen and phosphorus compounds that contribute to eutrophication. SDG indicator 14.1.1 specifically addresses coastal eutrophication through an index that includes nutrient loading^[7]. Agricultural activities are a primary source of nutrient emissions, particularly through application of fertilizers and management of livestock manure, as documented in the SEEA Agriculture, Forestry and Fisheries (SEEA AFF) guidance on nutrient flow accounts^[8]
• Organic matter -- measured through biological oxygen demand (BOD) and chemical oxygen demand (COD), indicating substances that affect oxygen balance in receiving waters
• Heavy metals -- including mercury, cadmium, lead, and other metals that accumulate in marine food chains
• Persistent organic pollutants -- chemicals that resist degradation and bioaccumulate, including legacy pollutants such as PCBs and contemporary substances of concern
• Oil and petroleum products -- from operational discharges, spills, and urban runoff
• Pharmaceuticals and personal care products -- emerging contaminants of increasing concern for marine ecosystems

Microplastics--particles less than 5mm resulting from fragmentation of larger items or manufactured as primary microplastics (e.g., microbeads, pellets)--represent a growing concern for marine ecosystems. In accounting terms, microplastics may be classified as either waterborne emissions (when suspended in wastewater) or solid waste (when accumulated in sediments or on shorelines). Compilers should adopt a consistent treatment and document their classification choice.

For ocean accounting, the water emissions account should be extended to distinguish between:

• Emissions to inland water resources that subsequently flow to marine waters
• Emissions directly to coastal and marine waters
• Emissions collected by sewerage systems with discharge to marine waters

The SEEA Technical Note on Water Accounting provides detailed guidance on the structure of water emission accounts, including treatment of point and non-point sources^[9].

3.2.2 Atmospheric emissions affecting marine waters

Certain atmospheric emissions ultimately deposit in ocean waters and contribute to marine environmental change. Air emissions accounts record gaseous and particulate substances released to the atmosphere by establishments and households^[10]. Substances of particular relevance for marine impacts include:

• Carbon dioxide (CO2) -- contributing to ocean acidification through absorption of atmospheric CO2 by ocean surface waters. Ocean acidification affects calcifying organisms including corals, molluscs, and some plankton species, with implications for marine food webs and fisheries productivity
• Nitrogen compounds (NOx, NH3) -- contributing to atmospheric deposition of nitrogen to marine waters, supplementing waterborne nutrient loading
• Sulphur compounds (SOx) -- contributing to atmospheric deposition and affecting marine chemistry
• Mercury and other metals -- depositing through wet and dry atmospheric deposition, entering marine food chains

The accounting challenge is to link atmospheric emissions to their marine deposition, which requires integration with atmospheric modelling or use of deposition coefficients. The SEEA CF notes that such atmospheric transfers occur within the environment and are generally not recorded in the air emissions account; however, for ocean accounting purposes, the atmospheric pathway from economic activity to marine impact may warrant supplementary recording^[11].

Ocean acidification--the decrease in ocean pH resulting from absorption of atmospheric CO2--represents one of the most significant indirect pathways from economic residual flows to marine environmental change. The ocean absorbs approximately 25-30% of anthropogenic CO2 emissions, with measurable effects on marine chemistry. SDG indicator 14.3.1 tracks ocean acidification using mean marine acidity (pH) measurements. For ocean accounts, the air emissions account provides the upstream measure (CO2 generated by economic activity), while the ecosystem condition account captures the downstream effect (changes in ocean pH).

The carbon cycle illustrates how carbon flows between the atmosphere, biosphere, oceans, geosphere, and the economy. Understanding this cycle is essential for compiling residual flow accounts that capture the full pathway from economic emissions to marine environmental impact. Figure 3.4.1 presents the main components of the carbon cycle as described in SEEA EA^[12].

Figure 3.4.1: Main components of the carbon cycle (adapted from SEEA EA Figure 13.1)^[13]

For ocean accounting, the key pathways include: emissions from combustion of fossil fuels (geosphere → economy → atmosphere), ocean uptake of atmospheric CO2 (atmosphere → oceans), and sequestration by coastal ecosystems such as mangroves and seagrasses (atmosphere → biosphere). The residual flow accounts described in this Circular capture the economy-to-atmosphere pathway; the ecosystem service accounts in TG-3.2 Flows from Environment to Economy capture the ocean and biosphere absorption pathways.

3.2.3 Marine-specific pollution sources

Certain pollution sources are specific to marine environments:

• Vessel emissions -- discharges from ships including bilge water, ballast water (with associated invasive species risk), sewage, and cargo residues. The International Maritime Organization's MARPOL Convention provides regulatory framework for these discharges^[14]. Ballast water management is also addressed under the IMO Ballast Water Management Convention (2004, entered into force 2017)
• Offshore operational discharges -- produced water from oil and gas extraction, drilling fluids, and platform discharges. Guidance on offshore energy accounting is provided in TG-3.10 Offshore Energy
• Aquaculture effluent -- nutrient-rich discharges, pharmaceutical residues, and organic matter from marine aquaculture operations. These flows should be recorded as part of aquaculture industry emissions (ISIC 0321)
• Port operations -- dredging spoils, stormwater runoff, and operational discharges from port facilities

3.3 Solid Waste

Solid waste accounts organise information on the generation of solid waste and the management of flows to recycling facilities, controlled landfills, or the environment^[15]. For ocean accounting, the critical concern is marine litter -- solid waste that enters the marine environment.

3.3.1 Marine litter and plastics

Marine litter comprises manufactured or processed solid material that enters the marine environment from any source^[16]. SDG Target 14.1 calls for prevention and significant reduction of marine pollution of all kinds, including marine debris, with indicator 14.1.1 including floating plastic debris density^[17].

Plastic pollution is the dominant component of marine litter by item count and is of particular concern due to:

• Persistence in the marine environment over decades to centuries
• Fragmentation into microplastics (particles less than 5mm) that enter marine food webs
• Accumulation in ocean gyres, coastal areas, and deep-sea sediments
• Harm to marine fauna through ingestion and entanglement

The TNFD disclosure framework identifies plastic pollution as a specific metric for nature-related disclosure, including plastic footprint measured as total weight of plastics used or sold, disaggregated by reusable, compostable, and technically recyclable categories^[18].

The international framework for plastic pollution management is evolving. The UN Environment Assembly initiated negotiations for an international legally binding instrument on plastic pollution (UNEA Resolution 5/14, 2022), which may establish new reporting requirements that complement ocean accounting frameworks. Compilers should monitor developments in this area.

3.3.2 Accounting for solid waste flows to marine environment

The SEEA solid waste account structure can be adapted for ocean accounting by:

1. Identifying marine leakage pathways -- waste that escapes from collection systems, landfills, or other waste management infrastructure and enters marine waters
2. Recording direct dumping -- waste disposed directly into marine waters (noting that ocean dumping is regulated under the London Convention and Protocol)
3. Tracking coastal and riverine sources -- waste from coastal zones and rivers that enters the marine environment

Compilation requires estimation of:

• Waste generated by coastal industries and households
• Share of mismanaged waste that reaches marine waters
• Waste transported by rivers to the ocean
• Waste generated by marine activities (shipping, fishing, offshore operations)

The European Waste Catalogue (EWC-Stat) classification provides a basis for categorising solid waste types, with particular attention to:

• Plastic waste by polymer type and product category
• Fishing gear (abandoned, lost, or discarded fishing gear -- ALDFG)
• Packaging waste
• Single-use products

The SF-MST (Statistical Framework for Measuring the Sustainability of Tourism) provides guidance on tourism solid waste accounting that can inform measurement of coastal tourism waste generation^[19].

3.4 Compilation Procedure for Physical Flow Accounts

The physical supply and use table for residuals records the generation of residuals by economic units (supply) and their destination (use). Table 1 provides a comprehensive residual flow account template for ocean-related economic activities following the SEEA CF structure^[20].

Table 1: Residual Flow Account Template (Physical Supply-Use)

SUPPLY OF RESIDUALS (by generating industry)

USE OF RESIDUALS (by receiving medium or treatment)

Note: This is a worked example with synthetic data illustrating the account structure. The supply-use identity requires Total Supply = Total Use for each residual type. The "Collection & Treatment" column records residuals that are collected by waste management industries rather than released directly to the environment. "Marine Water" includes direct discharges and untreated coastal runoff. Atmospheric emissions may subsequently deposit in marine waters but are recorded in the atmosphere use column following SEEA CF convention.

3.4.1 Compilation steps

The compilation procedure for residual flow accounts follows these steps:

Step 1: Identify industries in scope

Determine which industries generate significant residuals that reach marine waters, either directly or indirectly. Use the ISIC classification framework detailed in TG-3.3 Economic Activity Relevant to the Ocean. At minimum, include:

• Marine-based industries: fishing (ISIC 03), shipping (ISIC 50), offshore extraction (ISIC 06)
• Coastal industries: aquaculture (ISIC 03), ports (ISIC 52), fish processing (ISIC 10), coastal tourism (ISIC 55-56)
• Land-based sources: agriculture (ISIC 01), manufacturing (ISIC 10-33), sewerage (ISIC 37)
• Households in coastal drainage basins

Step 2: Determine substance priorities

Select substances based on policy relevance, data availability, and environmental significance. Priority substances typically include:

• Air emissions: CO2, SOx, NOx (linked to acidification and deposition)
• Water emissions: nitrogen, phosphorus, BOD, COD, heavy metals, oil
• Solid waste: plastics (by type), fishing gear, general waste

Step 3: Compile supply-side data

For each industry-substance combination, estimate the quantity generated using:

• Direct measurement from monitoring systems (e.g., continuous emissions monitoring)
• Activity data × emission factors (e.g., fuel consumption × CO2 coefficient)
• Industry surveys and reporting systems
• Administrative records (discharge permits, waste manifests)
• Modelling (e.g., nutrient loading models for agriculture)

Sources are detailed in Section 4 (Data Sources and Compilation).

Step 4: Compile use-side data

Track the destination of residuals:

• Atmosphere: all air emissions by convention
• Marine water: direct discharges + untreated coastal runoff + riverine transport
• Seabed: dumped waste, settled solids
• Collection & treatment: residuals entering waste management systems
• Recycling: recovered materials

Step 5: Balance supply and use

Verify that Total Supply = Total Use for each substance. Discrepancies indicate:

• Missing treatment/disposal pathways
• Unaccounted intermediate flows (e.g., retention in soils or freshwater systems)
• Measurement error requiring reconciliation

Step 6: Extend with spatial disaggregation

Where feasible, disaggregate accounts by:

• Drainage basin (for land-based sources) -- see Section 3.5.3
• Marine area (coastal zone, EEZ zones)
• Ecosystem receiving area (coral reef, mangrove, open water)

This spatial extension supports targeted pressure assessment and links to ecosystem condition accounts.

3.5 Attribution to Economic Sectors

A fundamental principle of environmental-economic accounting is the attribution of residual flows to the economic units responsible for their generation. This attribution enables:

• Analysis of which industries contribute most to environmental pressures
• Assessment of intensity (emissions per unit output or value added)
• Policy targeting and evaluation
• Responsibility allocation for environmental management

3.5.1 Classification framework

The International Standard Industrial Classification of All Economic Activities (ISIC) provides the standard framework for classifying economic units by industry^[21]. Detailed guidance on ISIC application for ocean-related activities is provided in TG-3.3 Economic Activity Relevant to the Ocean. Key industries for ocean-related residual flows include:

Primary industries

• ISIC 01-03: Agriculture, forestry and fishing -- sources of nutrient runoff, aquaculture discharges
• ISIC 05-09: Mining and quarrying -- offshore extraction discharges, drilling wastes

Manufacturing

• ISIC 10-33: Manufacturing -- industrial discharges, waste generation, including fish processing (ISIC 1020)

Utilities and waste management

• ISIC 35: Electricity, gas, steam and air conditioning supply -- cooling water discharges, emissions from power generation
• ISIC 36-39: Water supply, sewerage, waste management -- wastewater discharges, solid waste flows

Transport

• ISIC 50: Water transport -- vessel emissions and discharges, ballast water, operational waste
• ISIC 52: Warehousing and support activities for transportation -- port operations

Tourism and recreation

• ISIC 55-56: Accommodation and food service -- coastal tourism waste and wastewater
• ISIC 79: Travel agency and related activities -- tourism-related pressures
• ISIC 93: Sports, amusement and recreation -- marine recreation impacts

Construction

• ISIC 41-43: Construction -- coastal development, dredging, infrastructure installation

Table 2 provides an illustrative example of how key residual types can be attributed to the industries that generate them, following the ISIC classification used in TG-3.3 Economic Activity Relevant to the Ocean.

Table 2: Illustrative Attribution of Residual Types to Ocean Industries

3.5.2 Attribution methodology

The physical supply table for residuals records the generation of residuals by industry sector, with the use table recording their destination (collection by waste management, flows to environment)^[22]. Key methodological considerations include:

1. Point source versus non-point source -- point sources can be directly attributed to specific industries; non-point sources (e.g., agricultural runoff, urban stormwater) require modelling or allocation methods

2. Direct versus indirect flows -- industries may generate residuals that flow directly to the environment or that are collected by other economic units (e.g., sewerage industry) before environmental release

3. Residence principle -- following national accounts conventions, residual flows are attributed to the resident economic unit generating them, regardless of where the release occurs. This is particularly relevant for shipping, where vessel emissions in foreign or international waters are attributed to the country of the vessel operator's residence^[23]

4. Territorial versus production-based attribution -- territorial accounts record emissions within national territory; production-based accounts attribute emissions to resident producers. For marine emissions, territorial accounts would include emissions within the EEZ while excluding emissions from resident vessels operating elsewhere

5. Consumption-based attribution -- for comprehensive assessment, consumption-based attribution allocates emissions embodied in imported goods to the consuming economy. This requires input-output analysis linking production emissions to final consumption^[24]

3.5.3 Spatial attribution using drainage basins

A key challenge in ocean accounting is attributing land-based pollution flows to specific marine areas. Drainage basins--the geographic areas from which surface water flows to a common outlet such as a river mouth or coastal discharge point--provide a natural spatial framework for linking terrestrial economic activity to marine pollution pressures^[25]. By overlaying information on economic activity and population distribution with drainage basin boundaries, compilers can estimate the contributions of specific land areas to residual flows reaching the coast.

Allocation from national totals

Where SEEA CF water emission accounts or solid waste accounts have been compiled at the national level, these totals can be allocated to drainage basins using spatially detailed indicators of economic activity. For example, if the national water emissions account records that agriculture generates 5,000 tonnes of biological oxygen demand (BOD) per year, and a particular drainage basin contains 60% of the nation's agricultural employment, an initial estimate of BOD generated by agriculture in that basin would be 3,000 tonnes per year. This activity-proportional allocation approach can be applied to any industry for which suitable spatial indicators are available, such as employment counts, output data, or land-use statistics^[26].

The allocation formula is:

Residual flow in basin i = National residual flow × (Activity indicator in basin i / National activity indicator)

Example spatial indicators by industry:

• Agriculture (ISIC 01): agricultural employment, fertilizer sales by district, irrigated area
• Manufacturing (ISIC 10-33): industrial employment, facility locations, output by region
• Households: population in drainage basin, housing units
• Aquaculture (ISIC 03): licensed farm locations, production tonnage by basin

Bottom-up estimation from activity data

Where no SEEA CF flow accounts exist at the national level, compilers can estimate residual flows by applying per-unit emission or waste generation factors to spatially detailed data on economic activity and population. For example, if 5,000 people reside within a drainage basin and the estimated per-capita generation rate of untreated solid waste is 0.365 tonnes per year, the population in that basin generates approximately 1,825 tonnes of untreated solid waste annually. Such per-capita and per-unit factors may be drawn from national waste surveys, regional studies, or international benchmarks and applied to census or administrative data at the drainage basin level.

General formula:

Residual flow = Activity level × Emission/waste factor

Example emission factors:

• Nutrient loading from agriculture: kg N per hectare of fertilized cropland
• BOD from households: kg BOD per capita per year for unsewered population
• Plastic waste: kg plastic per capita per year × share mismanaged × share reaching marine environment

Transport and retention considerations

It should be noted that not all residuals generated within a drainage basin necessarily reach the ocean. Retention in soils, uptake by vegetation, storage in freshwater systems, and losses during transport may reduce the quantity ultimately reaching marine waters. Treatment systems (sewerage networks, wastewater treatment plants) intercept and process portions of the generated load before discharge. Compilers should:

• Document assumptions about retention rates and treatment coverage
• Use watershed models where available to estimate delivery ratios (proportion of generated load reaching the coast)
• Distinguish between generated residuals (all sources within the basin) and delivered residuals (those reaching marine waters)

For example, if agricultural activities generate 3,000 tonnes BOD per year in a drainage basin, but watershed modelling indicates that only 40% of nutrient loading reaches coastal waters due to riparian vegetation, wetland filtration, and in-stream processing, the delivered load would be 1,200 tonnes BOD per year.

Marine redistribution

Conversely, residuals that do reach the ocean may not remain at the point of coastal discharge; ocean currents, tides, and biogeochemical processes redistribute pollutants over time and space. Further dispersion modelling would be required for more precise estimates of marine pollution loading and exposure patterns. Nonetheless, linking land-based sources of pollution with coastal and marine conditions through drainage basin attribution represents a critical first step in connecting economic drivers to environmental outcomes.

Implementation guidance

Including terrestrial and freshwater areas in the spatial database underlying ocean accounts facilitates estimation of land-based sources of pollution and supports integrated catchment-to-coast analysis as outlined in TG-3.1 Physical Flow Accounts. Practical steps include:

1. Obtain drainage basin boundaries from hydrological datasets (national water agencies, HydroSHEDS, regional GIS layers)
2. Overlay economic activity data (employment, facilities, land use) using GIS
3. Calculate activity shares by basin for each relevant industry
4. Apply shares to national residual flow totals, or apply emission factors to basin-level activity data
5. Adjust for treatment coverage and delivery ratios where data permit
6. Document methodology, data sources, and assumptions in account metadata

This methodology supports policy analysis by identifying:

• Which drainage basins contribute most to coastal pollution
• Which industries within priority basins require intervention
• Where land-use planning and waste infrastructure investments would have greatest marine benefit

Guidance on linking these residual flow estimates to marine ecosystem condition and pressure indicators is provided in TG-2.7 Environmental Pressures.

3.6 Physical Pressures

Beyond material pollution, economic activities exert physical pressures on marine ecosystems that do not involve material flows but nonetheless affect ecosystem condition and function. These pressures are increasingly recognised in ecosystem accounting frameworks, including SEEA Ecosystem Accounting guidance on ecosystem condition indicators^[27].

3.6.1 Underwater noise

Anthropogenic underwater noise is a significant marine pressure, particularly affecting marine mammals and other species that rely on acoustic communication and echolocation^[28]. Sources include:

• Shipping -- continuous low-frequency noise from vessel propulsion and machinery
• Seismic surveys -- high-intensity impulsive noise from airguns used in oil and gas exploration
• Pile driving -- high-intensity impulsive noise from construction of offshore infrastructure including wind farms
• Sonar -- military and commercial sonar systems
• Dredging and drilling -- operational noise from coastal and offshore construction

The Classification of Environmental Protection Activities (CEPA) includes noise and vibration abatement (CEPA 5), covering activities aimed at control, reduction, and abatement of industrial and transport noise^[29]. For ocean accounting, this framework can be adapted to address underwater noise from maritime activities.

Accounting for underwater noise requires:

• Identification of noise-generating activities and their acoustic characteristics
• Spatial mapping of noise exposure in marine areas
• Attribution to economic sectors responsible for noise generation
• Recording of mitigation measures (e.g., speed reductions, operational restrictions, noise barriers)

Underwater noise measurement remains an emerging field with limited standardisation. The IMO has developed voluntary guidelines for reducing underwater noise from commercial shipping (MEPC.1/Circ.833), and several regional seas conventions have adopted noise monitoring indicators. Compilers may need to collaborate with marine scientists to develop appropriate noise indicators for their accounting area and should document the measurement methods used. For quality considerations regarding emerging indicators, see TG-0.7 Quality Assurance.

3.6.2 Light pollution

Artificial light at night (ALAN) affects marine and coastal ecosystems, disrupting navigation, reproduction, and predator-prey relationships for marine species including sea turtles, seabirds, and coral spawning^[30]. Sources include:

• Coastal urban lighting
• Offshore platform lighting
• Vessel lighting
• Fishing operations using light attraction

Light pollution accounting would record:

• Light emissions from coastal installations by industry sector
• Light emissions from vessels and offshore structures
• Mitigation measures (shielded lighting, reduced illumination periods)

3.6.3 Habitat disturbance

Physical disturbance of marine habitats results from activities including:

• Bottom trawling -- physical impact on seabed habitats from mobile fishing gear
• Dredging -- removal of sediments from ports, channels, and coastal areas
• Coastal development -- construction affecting coastal and nearshore habitats
• Cable and pipeline installation -- seabed disturbance from infrastructure installation
• Anchoring -- localised damage from vessel anchoring, particularly on sensitive habitats such as seagrass and coral

The SEEA Ecosystem Accounting framework addresses ecosystem modification and habitat disturbance as factors affecting ecosystem condition^[27:1]. For ocean accounting, physical pressures should be recorded in terms of:

• Area affected by disturbance type and economic activity
• Intensity or severity of disturbance
• Recovery status where applicable

Guidance on linking physical pressures to ecosystem condition accounts is provided in TG-2.3 Ecosystem Condition.

3.7 Combined Presentations and Indicators

The SEEA framework supports combined presentations that bring together physical and monetary data to enable derivation of indicators^[31]. For residual flows to the marine environment, combined presentations would include:

Table 3: Combined Presentation Framework for Ocean-Related Residual Flows

From such presentations, indicators can be derived including:

• Emissions intensity: emissions per unit GVA or output (e.g., kg N per million currency of aquaculture output)
• Waste generation intensity: tonnes waste per FTE (e.g., kg plastic per employee in fishing industry)
• Environmental expenditure share: environmental expenditure as percentage of industry output
• Decoupling indicators: tracking emissions relative to economic growth (e.g., ratio of emission growth rate to GDP growth rate)

Example derived indicators:

This analysis reveals that while agriculture generates a larger absolute load, aquaculture has lower emissions intensity per unit of economic output in this example. Such indicators support:

• Benchmarking across industries and jurisdictions
• Monitoring progress toward pollution reduction targets
• Identifying high-intensity activities for policy intervention
• Evaluating effectiveness of environmental protection expenditure

Guidance on indicator derivation and interpretation is provided in TG-2.7 Environmental Pressures and TG-2.11 Resource Efficiency.

3.8 Cross-Stack Connections

Residual flow accounts sit at the center of an integrated information system linking economic drivers, environmental pressures, ecosystem condition, and policy responses:

Upward connections (to indicators and policy frameworks):

• TG-2.7 Environmental Pressures -- derives pressure indicators from residual flow data (nutrient loading rates, plastic leakage, emission trends)
• TG-2.8 Ecosystem Degradation -- links CO2 emissions to ocean acidification indicators and climate-related marine impacts
• SDG 14.1.1 -- coastal eutrophication index draws on nutrient loading data; floating plastic debris density draws on plastic waste flows
• TNFD disclosures -- plastic pollution metrics and pollution-related dependencies

Downward connections (to data sources):

• TG-4.2 Survey Methods -- industry surveys on waste generation, environmental practices
• TG-4.3 Administrative Data -- discharge permits, compliance monitoring, waste manifests, ship reporting systems
• TG-4.4 Earth Observation -- satellite detection of oil spills, floating debris, coastal development
• National pollution inventories, water quality monitoring networks, marine litter surveys

Lateral connections (to related physical accounts):

• TG-3.1 Asset Accounts -- links residual flows to changes in asset quality (water quality degradation, seabed contamination)
• TG-3.2 Flows from Environment to Economy -- contrasts resource extraction flows with waste return flows
• TG-3.3 Economic Activity -- provides ISIC framework for industry attribution
• TG-3.5 Flows within the Environment -- tracks redistribution of pollutants by currents, tides, biogeochemical processes

These connections ensure that residual flow accounts contribute to a coherent analytical framework rather than standing as isolated statistics.

4. Data Sources and Compilation

Compilation of residual flow accounts for ocean accounting draws on multiple data sources. TG-4.3 Administrative Data provides detailed guidance on administrative data sources for ocean accounting.

Key data sources include:

Environmental monitoring data

• National pollution inventories and emission reporting systems
• Water quality monitoring networks (coastal stations, estuarine monitoring)
• Marine litter surveys and monitoring programmes
• Beach cleanup data and citizen science initiatives

Administrative records

• Discharge permits and compliance monitoring (point sources)
• Waste management records and tracking systems
• Port reception facility records (MARPOL waste from vessels)
• Ship monitoring and reporting systems (fuel consumption, ballast water exchange)
• Aquaculture licensing and feed records

Survey data

• Industry surveys on environmental practices
• Waste characterisation studies
• Tourism surveys for visitor-generated waste estimation
• Fishing gear loss surveys

Modelling and estimation

• Atmospheric deposition models (linking air emissions to marine deposition)
• River loading models (watershed models estimating pollutant delivery)
• Waste leakage models (e.g., Jambeck methodology for plastic waste)^[32]
• Nutrient balance models for agriculture

International reporting frameworks

• UNFCCC greenhouse gas inventories (CO2, CH4, N2O by sector)
• UNECE Convention on Long-Range Transboundary Air Pollution reporting
• Regional seas convention reporting (e.g., OSPAR, HELCOM, Barcelona Convention)
• IMO reporting under MARPOL (vessel discharges and emissions)

Example data pathway: Nutrient loading from agriculture

1. Activity data: Agricultural census provides hectares of cropland by district and drainage basin
2. Emission factor: National studies estimate 45 kg N per hectare leached from fertilized cropland
3. Initial estimate: 10,000 hectares in Coastal Basin A × 45 kg N/ha = 450,000 kg N generated
4. Delivery adjustment: Watershed model indicates 35% delivery ratio to coast → 157,500 kg N delivered
5. Account entry: Agriculture (ISIC 01) in Basin A contributes 157.5 tonnes N to coastal waters

Quality assurance considerations for residual flow accounts are addressed in TG-0.7 Quality Assurance.

5. Acknowledgements

This Circular has been approved for public circulation and comment by the GOAP Technical Experts Group in accordance with the Circular Publication Procedure.

Authors: [Names and affiliations]

Reviewers: [Names and affiliations]

6. References