The Solent Forum

Working in partnership for the future

Polluting Contaminants

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The Water Environment Regulations (WER) 2017 (emerging from the Water Framework Directive) are the main legal instrument for water quality protection in England including for transitional and coastal waters. They detail the elements that need to be taken into account in assessing ecological and chemical status, set environmental water quality standards and regulate chemicals identified as priority substances, including a sub-set of priority 'hazardous' substances. 

The WER, 2017 actions are taken forward in River Basin Management Plans such as the South East RBMP which includes the Solent, see Solent Forum - River Basin Management Plans.

Polluting substances Monitored in the River Basin Management Plans

Water Quality Objectives for River Basin Management Plans

The Water Environment Regulations 2017 set surface waters objectives for good ecological and chemical status. For artificial or heavily modified surface water bodies, such as the Solent, the objectives are set for good ecological potential and chemical status. Target dates vary and tend to be by 2027 although in some cases for chemical status it can be as long 40 years to achieve. Some chemicals, known as ubiquitous persistent, bio accumulative and toxic substances (uPBTs), can remain in the water environment for decades after actions to reduce or eliminate emissions are in place. The target date of 2063 for achieving good status for some of these chemicals, where the required actions are already in place, reflects this extended recovery time.

Priority Chemicals and other Potentially Damaging Chemicals

The identification of priority chemicals is a challenge for regulators, managers and researchers as the overall number of chemicals lies in the 10’s of thousands. A report commissioned by the EU in 2017, 'Potential chemical contaminants in the marine environment,' provided an overview. It compiled a list of more than 2700 chemical substances (or groups of substances) compiled by relevant global conventions, European legislation and dedicated research work. There is a lack of ecotoxicity data for both vertebrates and invertebrates. Even less is known about the potential impact of chemicals such as fungicides and antimicrobials on microorganisms.

The Environment Agency use environmental quality standards (EQSs), which are regularly reviewed, to assess these chemicals. They consider two categories of chemicals when assessing the chemical status of surface waters -  Priority and Priority hazardous substances.


Priority Substances

Priority Hazardous Chemical Substances 

Ecological Status

The ecological Status classification of a waterbody is derived from individual quality element assessments for biology, physico-chemical parameters and specific pollutants, as well as hydromorphological assessments and a check of Invasive Non-Native Species (INNS). Ecological Status is reported as High, Good, Moderate, Poor or Bad. Artificial and Heavily Modified Water Bodies (A/HMWBs), like the Solent, are classified using Ecological Potential. The Solent is currently at moderate ecological potential.


Specific pollutants

Chemical status within RBMPs

The Environment Agency produced a consultation document on chemicals in the water environment which considered priority and priority hazardous substances when assessing the chemical status of surface waters. It set out how to understand whether chemicals are causing stresses on the aquatic environment by measuring data against EU environmental quality standards (EQSs). The following concerns were found since 2016:

More information on chemical status and how a more advanced approach to classify the more peristant substances can be found in the EAs River Basin process overview report March 2023. 

Solent Context and Issues

The Solent has priority chemical failures for:

The ecological status of the Solent has elements that are moderate and poor for the following attributes.  See the Solent Forum RBMP section linked above.

The Solent benefits from a rich source of studies on water quality and the effects of chemicals in the marine environment.


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