Short description
This indicator will track changes in the inputs and discharges of selected contaminants such as nutrients and some toxic chemicals to rivers or directly to the sea, for example through sewage pipelines or activities such as agriculture inputting substances directly.
It will focus on the discharge/emission of contaminants that adversely affect the quality and uses of receiving waters and potentially increase the costs of water treatment. These also affect the wildlife and ecology of rivers, estuaries and coastal waters.
Data will be derived from the existing Riverine Input and Direct Discharges (RID) data collected under the Convention for the Protection of the Marine Environment of the North-East Atlantic (OSPAR) and the Environment Agency’s Emissions Inventory.
Readiness and links to data
This indicator is not available for reporting in 2021 in a finalised form. An interim indicator is presented here that shows relative changes in measured riverine loads (inputs) of selected metals and nutrients into English tidal waters between 2008 and 2019, covering cadmium, copper, lead, mercury, zinc, nitrogen and ortho-phosphate. Some data for this interim indicator have previously been published as part of the OSPAR assessments (Inputs of Mercury, Cadmium and Lead via Water and Air to the Greater North Sea) although for different time periods and so these data should be compared with caution. Further development is required to present statistical trends for the selected contaminants in an indicator. These data are taken from the existing OSPAR database. The Environment Agency reports a subset of these data to Defra on an annual basis known as the RIDS dataset, ‘Riverine and Industrial Discharges’ Contact the Environment Agency’s National Customer Contact Centre for the OSPAR database extract used for the interim indicator.
Note
Load (input) calculations (kg/day) are the product of the monitored concentration of substance and flow rate. The annual total loads (kg/year) for selected metals (total fraction), total nitrogen and ortho-phosphate are calculated using chemical concentration data reported in the Water quality data Archive and flow data reported in the Environment Agency’s core system of hydrometric and hydrological values (Water Information System by Kisters).
Observed fluctuations in the data could be influenced by a number of external factors affecting movement and loading within river systems such as flow caused by high or low rainfall in a given year or local impacts of changing industry or land use over time. Also, flow and load in 2008 were high compared to most years in the reporting period which influence the reduction seen against 2019.
Trend description
a) Riverine inputs of selected metals
Riverine inputs of cadmium, copper, lead, mercury and zinc into English tidal waters have fluctuated considerably between 2008 and 2019, but overall they have all fallen. Measured loads of cadmium, mercury, copper, zinc and lead were 49%, 45%, 41%, 32% and 21% respectively less in 2019 than they were in 2008.
b) Riverine inputs of selected nutrients
Riverine inputs of total nitrogen and ortho-phosphate have also fluctuated considerably between 2008 and 2019 but overall, both have fallen, and both have remained below their baseline value with measured loads in 2019 being 41% and 49% respectively less than those measured in 2008.
