Rivers – Nutrients, Organic Matter and General Physico-Chemical Determinands

Table 1 provides an overview by determinands (highest priority nutrients) of the number of river stations per year for the period 1992 to 2012.  

Note: In the current data set the reporting of some high priority determinands has stopped or there has been a change in the determinands in the database (e.g. CODMn/CODCr). EEA wants to clarify if these changes are real changes or it has been errors/misinterpretations introduced in compiling the databases. In addition, the aim is to ensure that the high priority determinands (e.g. nitrate or orthophosphate) have as complete temporal and spatial coverage as possible.

Country specific text to be added. Country reports data on nutrients in rivers since year. (Table 1).

Sweden has been reporting data from nutrients in rivers from 1965 on. Table 1 below provides an overview by determinands of the number of river stations per year for the period 1992 to 2012.

Table 1: Number of river stations per determinand/year (nutrients of highest EEA priority)

Note: One aspect of the quality factsheet is to improve the spatial coverage and ensure that stations are reported for all RBDs.

Table 2 shows the number of river stations by River Basin Districts which reported on nutrients for the period from 1992 – 2012. Sweden reported data from around 127 river stations for nutrients in 7 RBDs in this period. The reporting on nutrients was stable during this period.

Table 2: Number of river stations for nutrients by River Basin Districts for the period 1992 – 2012

The figure below illustrates the river stations with nutrient reporting in 2013 (covering the year 2012) in Sweden.

Figure 1: SoE river stations with nutrient data reported in 2013 in Sweden`s RBDs

Note: EEA water quality indicators are used for trend assessments based on consistent time series with some gap filling. For a single country consistent time series are established for the defined period (e.g. 1992-2012; or 2000-2012) with some gap filling (e.g. up to 3 years) and only stations with values for all years in the defined period are used. This ensures that any trend is because of change in the observations and not in the stations included.

For the period 1992 to 2012 Sweden has reported around 127 river stations with monitoring of total oxidised nitrogen, nearly all stations have a very long period - 21 years - of observation (Table 3).

Table 3: Length of total oxidized nitrogen time series in Sweden for period 1992 – 2012 (value in the table fields is number of stations with x years’ time series)

 

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Note: In the current data set the reporting of some high priority determinands has stopped or there has been a change in the determinands in the database (e.g. CODMn/CODCr). EEA wants to clarify if these changes are real changes or it has been errors/misinterpretations introduced in compiling the databases. In addition, the aim is to ensure that the high priority determinands (e.g. nitrate or orthophosphate) have as complete temporal and spatial coverage as possible.

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Questions to Sweden regarding the reporting on general water quality in rivers:

1. Clarifying questions on data in current database

- question 1 CODCr has been changed to CODMn in 2004 – what is the reason for this, was there a change in the methodology?

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- question 2 Not much data on BOD have been reported, are there more stations where BOD is measured? Can they be redelivered?

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- question 3

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2. Improving coverage of determinands, temporal and spatial coverage

- Can more stations be reported to increase spatial coverage?

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