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B5b. Marine pollution

Type: Pressure indicator

Introduction

The indicator shows the combined input of six of the most hazardous substances to the UK marine environment. The indicator is based on levels of five heavy metals (cadmium, mercury, copper, lead and zinc) and one organic compound (lindane). Pollution in the marine environment from these six substances should decrease to levels that are non-detrimental by 2020.

Key results

The combined inputs of all six of the hazardous materials included within this indicator have shown a long-term decrease of 78% since 1990. In the short term (since 2014), inputs of five out of six of these substances show decreases; one heavy metal (zinc) has increased.

Figure B5bi. Combined input of hazardous substances to the UK marine environment, as an index of estimated weight of substances per year, 1990 to 2019.

A line graph showing the combined input of hazardous substances to the UK marine environment, as an index of the estimated weight of substances per year from 1990 to 2019. The index has fluctuated considerably between 1990 and 2019 but overall, it has shown a long-term decrease of 78%.

Source: Defra Marine Strategy and Evidence Division, using data provided by: Environment Agency; Northern Ireland Environment Agency; and Scottish Environment Protection Agency.

Levels of all six substances declined over the period 1990 to 2019. The heavy metals, mercury, cadmium, lead, copper and zinc decreased by 91%, 88%, 59%, 59% and 55%, respectively. The organic compound lindane decreased by 86%.

In the short term, the combined inputs of all six hazardous substances decreased by 18% from 2014 to 2019 (using a three-year average for 2014). Inputs for five out of the six of the hazardous substances declined in the short term: lindane had the highest percentage decrease (-44%), cadmium decreased by 31%, mercury by 26%, copper by 8% and lead by 6%. By contrast, zinc increased by 17%.

Inputs into the marine environment are estimated from concentrations and flow rates in rivers entering the sea and those from estuarine and coastal point sources. Riverine inputs reflect both point and diffuse sources upstream of the sampling point and tend to be strongly influenced by flow rates. Flow rates are heavily affected by rainfall patterns so year-to-year fluctuations in pollutant loads are likely.

Assessment of change in input of hazardous substances to the marine environment

  Long term Short term Latest year
Combined input of hazardous substances


1990–2019

Improving
2014–2019

Increased (2019)

Note: Long- and short-term assessments are based on a 3% rule of thumb. Where possible, the base years for these assessments use a three-year average. See Assessing Indicators.

A detailed illustration of changing levels of each input is seen in Figure B5bii. The low point in 2003 is thought to be a consequence of reduced river flows during an exceptionally dry year. Conversely, levels increased in 2012 and again in 2014 corresponding with years of heavy rainfall. In 2012, England had the wettest year since records began in 1910; the summer was the wettest since 1912 and increased rainfall in November and December contributed to extensive flooding. In 2014, the winter (January to February) was the wettest since records began.

Figure B5bii. Inputs of hazardous substances to the UK marine environment, as an index of weight of substance per year, 1990 to 2019.

A line graph showing the input of six hazardous substances to the UK marine environment, as indices of the estimated weight of each substance per year from 1990 to 2019. The six indices have fluctuated considerably between 1990 and 2019 but overall, they have all shown a long-term decrease of between 55% (zinc) and 91% (mercury).

Source: Defra Marine Strategy and Evidence Division, using data provided by: Environment Agency; Northern Ireland Environment Agency; and Scottish Environment Protection Agency.

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Relevance

Pollution by hazardous heavy metals and pesticides can have adverse effects on the marine environment and biodiversity. Pollutants enter coastal waters either directly from point sources on UK coasts and estuaries or are carried via rivers.

One of the goals of the Convention for the Protection of the Marine Environment of the North-East Atlantic (the OSPAR Convention) is to implement the Hazardous Substances Strategy by making progressive endeavours, through appropriate actions and measures, to move towards the targets of the cessation of discharges, emissions and losses of hazardous substances by the year 2020.

While many measures have already been put in place to prevent these persistent contaminants from entering the environment (for example, bans on lead in petrol, marketing restrictions on the use of cadmium and mercury, a ban on the use of lindane), there are still reservoirs of these contaminants from legacy use in soils and sediments which are mobilised by various weather events.

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Background

The assessment of change for the indicator was made by applying a 3% rule of thumb. The arithmetic mean of the first three years of the data series was compared with the last point to determine the assessment for the long-term trend, and an arithmetic mean of the year five years back in the time series and the year either side calculated to compare with the last point to assess the short-term trend.

Although data for total UK (direct plus riverine) inputs to the marine environment are available as lower and upper estimates, for ease of interpretation only upper (that is, maximum) values have been used in this assessment, rather than presentation of the data range for each substance. The values for each pollutant are converted to an index scaled to 100 at the start year of 1990, and then combined with a geometric mean.

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Goals and Targets

Aichi Targets for which this is a primary indicator

Strategic Goal B. Reduce the direct pressures on biodiversity and promote sustainable use.

Aichi Target 8 icon

Target 8: By 2020, pollution, including from excess nutrients, has been brought to levels that are not detrimental to ecosystem function and biodiversity.

Aichi Target for which this is a relevant indicator

Strategic Goal B. Reduce the direct pressures on biodiversity and promote sustainable use.

Aichi Target 10 icon

Target 10: By 2015, the multiple anthropogenic pressures on coral reefs, and other vulnerable ecosystems impacted by climate change or ocean acidification are minimized, so as to maintain their integrity and functioning.

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Reference Title
Convention for the Protection of the Marine Environment of the North-East Atlantic (OSPAR) Convention for the Protection of the Marine Environment of the North-East Atlantic (OSPAR)
Defra Clean Seas CP2 index of hazardous substances

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Downloads

Download the Datasheet from JNCC's Resource Hub.

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Last updated: October 2021

Latest data available: 2019

 

This content is available on request as a pdf in non-accessible format. If you wish for a copy please go to the enquiries page.

Categories:

UK Biodiversity Indicators 2021

Published: .

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