The Solent Forum
Working in partnership for the future
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.
In November 2024, a new bill that sets out legal limits for the use of a group of toxic chemicals known as PFAS was introduced to the UK Government, following pressure from world-leading scientists. Per- and polyfluoroalkyl substances (PFAS) are a complex group of nearly 15,000 synthetic substances used in consumer products around the world since the 1950s. They keep food from sticking to packaging or cookware, make clothes and carpets resistant to stains, and are found in firefighting foam. The so-called ‘forever chemicals’ don't break down easily in the environment. They have been linked to adverse effects on human health and wildlife.
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.
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
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.
Biological
Specific pollutants
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.
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.
Metals enter the marine environment from many sources such as industrial and sewage inputs, anti-fouling paints and sacrificial anodes. They often accumulate in sediments (e.g. mudflats) so sediment-dwelling worms such as king (Alitta virens) and harbour ragworms (Hediste diversicolor) are highly relevant for studying the effects. However, the ecological and biological differences in these species could influence their metal accumulation and suitability for monitoring contamination. A University of Portsmouth and partners study looked at trace element contamination and biomonitoring and in the Solent. This study is the first Solent-wide assessment of the sediment concentrations of the top 10 metals polluting our coasts combined with a species comparison of two ecologically and economically important species. Risk assessments to benthic species living in the sediments can now be generated, but these will likely change as future metal inputs could significantly increase under global decarbonisation.
This study measured sediment and tissue concentrations from multiple populations of these two species across the Solent (Chichester Harbour, Langstone Harbour, Portsmouth Harbour, Medina Estuary, Western Solent, Itchenor and Warsash). Despite diverse anthropogenic activity, the majority of metals present low levels of sediment contamination at the sites.
For nickel, lead and mercury, a combination of tissue and sediment concentrations indicate a slight toxicological risk, whilst copper, arsenic and mercury were the greatest risk to benthic species, thus requiring identification of the sources and their subsequent control. Except for cadmium, correlations between sediment and tissue concentration were generally negative indicating that both species' have limited scope as biomonitors for lower-contamination sites. Species differences in tissue concentration were also metal specific: H. diversicolor had significantly higher concentrations for silver, copper, mercury, nickel and zinc, whilst the reverse was true for cadmium, iron, chromium and arsenic. This suggests that the biochemical regulation processes to reduce metal toxicity differ between species.
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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