This is one chapter of The Invisible Wave, Back to Blue’s recent report on marine chemical pollution

Most marine chemical pollution begins on land—about 80% versus 20% thought to originate at sea, according to The Invisible Wave—with freshwater environments such as rivers and lakes providing direct or indirect routes to the ocean.

Yet, for several reasons, this 80:20 proportion is not as helpful as it might appear, says Dr Peter Kershaw, an independent consultant on marine environmental protection. For one thing, he says, you cannot apply it to every substance of concern, as they are released in different quantities in different regions and have different effects.

Another factor is the impact that chemicals have. While the global quantity of a particular chemical entering the ocean could be large, more damage might well be done in a particular area by a sea-based source of pollution—for example, the case in 2021 of a tanker carrying tons of nitric acid, other chemicals and plastic pellets that caught fire and sank off Sri Lanka.

The sources of marine chemical pollution, then, are varied and often complex. To try to make sense of them, The Invisible Wave breaks them down into six broad categories (which inevitably overlap to some degree):

  • the chemicals industry
  • other industries that use chemicals for their products and processes
  • consumers
  • public use and legacy chemicals
  • accidents and
  • waste management and disposal

The chemicals lifecycle: From raw material to disposal
Chemical pollution takes place at every stage of the process. According to UNEP, the industries responsible for the largest releases of hazardous chemicals include mining, agriculture, wastewater treatment, energy generation, chemical production, and product-manufacturing use and disposal

The chemicals sector value chain

Raw materials

Basic chemicals

Olefins (ethylene, propylene, butylene) Aromatics (benzene, toluene, xylenes)
Chlor-Alkali (chlorine, caustic soda) Methanol Bio-based materials (eg, sugars, starches, natural
oils and acids) Others (eg, ammonia, phosphorous)

Chemical intermediaries

Commodities Differentiated commodities Technical specialities

Formulated products and product materials

Plastics and engineering resins Extruded films, pipes, profiles, coatings, sheets,
foams Blow-molded parts Injection molded parts Composites Synthetic Fibres Rubber products Paints
and coatings Adhesives and sealants Lubricants Water treatment products Cleaning products Industrial
chemicals Flame retardants Many others…

Customers of the chemical sector

Automotive/transport Consumer products Packaging Building and construction
Recreation/sport Industrial Medical Pharmaceuticals Personal care Textiles Electrical/electronics
Aircraft/aerospace Food Bio-based materials

Source: Chemical Sector SDG Roadmap, World Business Council for Sustainable Development (WBCSD) (2018)

The Invisible Wave seeks to map accountability for marine chemical pollution across the chemicals lifecycle, from those involved in the pre-production phase—including extracting the fossil fuels, minerals and metals that are used to manufacture industrial chemicals—to those who make and use chemicals, and the public- and private-sector operators that manage the end-of-life waste process.

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