B5b. Marine pollution
Type of indicator: Pressure Indicator
This indicator was not updated in 2023. It was last updated in 2021.
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.
For this indicator, the most recent data are from 2019.
Due to recent data availability it has not been possible to update this indicator beyond 2019. This indicator uses annual averages so to be representative of the real life conditions it is important to capture seasonal patterns in the monitoring otherwise the averages would be skewed. The coronavirus pandemic severely impacted monitoring efforts during 2020. In England, no riverine monitoring was carried out during the months of April through to September and sampling from October to December was extremely limited compared to previous years. Similarly in Northern Ireland, no monitoring was carried out in April and May and in Wales monitoring was not possible between from April to July. This is expected to have a significant impact on the 2020 data, and they have therefore not been included in the indicator.
There was also reduced monitoring in 2021 compared to previous (pre-pandemic years). This was due to a number of factors including prioritisation of resources within the UK Administrations. The absence of data due to this reduction in monitoring made 2021 inputs appear low compared to previous years. The 2021 data have therefore not been included in the indicator.
Due to a complex cyber-attack that took place in December 2020, it is not possible to report 2020 or 2021 monitoring data for Scotland.
Contents
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Key results
- 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
- Assessment of change in input of hazardous substances to the marine environment
- Figure B5bii. Inputs of hazardous substances to the UK marine environment, as an index of weight of substance per year, 1990 to 2019
- Relevance
- Background
- Goals and Targets
- Web links for further information
- Downloads
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
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 |
Improving 1990–2019 |
Improving 2014–2019 |
Increased (2019) |
Notes for Assessment of Change table:
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
Source: Defra Marine Strategy and Evidence Division, using data provided by: Environment Agency; Northern Ireland Environment Agency; and Scottish Environment Protection Agency.
The detection limits for analysis have gradually decreased over the period of 1990 to 2023. This is likely to have caused an overestimation in the input levels for early years compared to more recent years, leading to the reported decreases being overestimates.
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.
Background
The assessment of change for the indicator was made by applying a 3% rule of thumb (see Assessing Indicators). 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.
Goals and Targets
The UK and England Biodiversity Indicators are currently being assessed alongside the Environment Improvement Plan Targets, and the new Kunming-Montreal Global Biodiversity Framework Targets, when this work has been completed the references to Biodiversity 2020 and the Aichi Global Biodiversity Framework Targets will be updated.
Aichi Targets for which this is a primary indicator
Strategic Goal B. Reduce the direct pressures on biodiversity and promote sustainable use.
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.
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.
Web links for further information
Downloads
Download the Datasheet from JNCC's Resource Hub.
Last updated: October 2021
Latest data available: 2019
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