Aarhus University Seal / Aarhus Universitets segl

No. 274: Water Environment and Nature 2016

Jensen, P.N., Boutrup, S., Fredshavn, J.R., Nielsen, V.V., Svendsen, L.M., Blicher-Mathiesen, G., Thodsen, H., Johansson, L.S., Hansen, J.W., Therkildsen, O.R., Holm, T.E., Ellermann, T., Thorling, L. & Holm, A.G. 2018. Vandmiljø og Natur 2016. NOVANA. Tilstand og udvikling - faglig sammenfatning. Aarhus Universitet, DCE – Nationalt Center for Miljø og Energi, 58 s. - Videnskabelig rapport fra DCE - Nationalt Center for Miljø og Energi nr. 274.  http://dce2.au.dk/pub/SR274.pdf 

Summary 

This report summarizes the results from the National Danish Monitoring program NOVANA for the year 2016 and the development in a number of parameters for the period 1990-2016. 

The reporting of 2016 data was influenced by the use of an unauthorized method for analyzing total nitrogen (TN) and total phosphorus (TP) in 2016 and the beginning of 2017. Prior to using the results, a “reconstruction” was necessary, which was finalized in March 2018. The unauthorized method only influences the organic part of TN and TP in surface water – not the dissolved inorganic parts. 

The unauthorized method was also used in the period 2008-14. It has not yet been possible to reconstruct these results, so they may need to be corrected.  

Nutrients 

Since 1990, there has been a nearly 50 % reduction in the content of nitrogen in surface water. Overall, this corresponds well with a reduction in the sources, here seen as the use of fertilizers and discharge from wastewater treatment plants. There was an increase in the nitrogen surplus from 2015 to 2016. 

Considering precipitation etc. (normalized), the load was 59.000 ton N in 2016, compared to 62.000 ton N in 2015. 

For phosphorus, it is a different situation. Since 1990, there has been a 50-60% reduction in the phosphorus content in surface waters, caused entirely by improved wastewater treatment, mainly in the larger plants, until the year 2000. 

In 2016, the total load of phosphorus to marine areas was in 2.300 ton P – somewhat less than in 2015. 

Metals and organic hazardous substances 

Zinc is one of the metals found most often in sediments from lakes and rivers and is the metal with the highest atmospheric deposition. In addition to zinc, metals like nickel, copper and lead have been found in the highest concentrations among heavy metals in rivers and lakes. In some cases, the concentrations of the three metals in rivers exceeded the environmental quality standards. 

Pesticides are among the substances measured in the monitoring program. As in previous years, the pesticide prosulfocarb was found in the highest concentration among the 19 pesticides analyzed in the rain samples. Prosulfocarb is also among the substances most frequently found in rivers. 

Among the organic substances are brominated flame retardants, which, as in previous years, in 2016 were detected in marine fish in concentrations exceeding the environmental quality standards. The tendency towards a decline in TBT content in marine areas seems to have continued in 2016. 

Air quality 

The main conclusions from air monitoring in 2016 are: 

  • The quality standard for nitrogen oxide (NO2) was exceeded at one (H.C. Andersens Boulevard) out of two street measuring stations in Copenhagen. There were no exceedances in the remaining parts of Denmark. 
  • No exceedances of the quality standards for particles were found. 
  • The concentration of ozone was at the same level as in 2015. The threshold for informing the public about high ozone levels was exceeded in 2016 at the measuring station at Risø. The Environmental Protection Agency informed the public about the high ozone levels. 
  • There has been no development in the deposition of Nitrogen during the resent years. 

Groundwater  

The different action plans for the environment have had an effect on the content of nitrate in groundwater. This is clearly seen in the connection between nitrate content in oxygenated groundwater and the nitrogen surplus in agricultural production. During the last 10 years, the average nitrate concentration in ground water that contains oxygen has varied around the quality standard of 50 mg/l. In 2016, one or more pesticides or metabolites were found in 34 % of the examined intakes in the monitoring program for groundwater. The quality standard of 0.1 ug/l was exceeded in 8.6 % of the intakes. In most cases, the exceedance was caused by pesticides or metabolites that are no longer allowed.  

Rivers

The proportion of water courses in at least good status (approx. 50 %) based on the appearance of invertebrates has been stable during the past 5 years – although at a lower level in 2016, probably due to insufficient sampling. This level is a significant improvement compared to 20 years ago, when the share was approx. 20%. 

Lakes 

In general, the development in central parameters such as chlorophyll a in lakes has been slightly positive during the period 1990-2016. The most significant improvements have been detected in lakes in which the pollution was most severe in 1990. 

Marine areas 

The oxygen depletion in August 2016 was considerably lower compared to the previous year, whereas the extent of oxygen depletion in September 2016 was considerably higher than in September 2015. 

The amount of algae in the coastal waters measured as chlorophyll a was higher in 2016 compared to the previous years and reached a level comparable to the level in the 1990’ies and the mid 2000’s.  

The appearance of higher plants (eelgrass and macro algae) has increased significantly during the past 10 years. 

Thus, when looking at the latest 10 years, there seem to be diverse signals from the various marine parameters. 

Habitat and species 

Monitoring results for habitats are available on novana.au.dk. In 2016, three marine mammals and four vascular plant species were monitored. Another three lamprey species were monitored in the NOVANA fresh water subprogram. 

The harbor seal (Phoca vitulina) and the grey seal (Halichoerus grypus) populations have both increased. Where the population of harbor seal seems to have reached the carrying capacity of the environment, the population of grey seal is expected to increase further over the coming years. The populations of the vascular plant species Fen orchid (Liparis loeselii), Marsh saxifrage (saxifrage hirculus), the Little Grapefern (Botrychium simplex) and Lady's Slipper orchid (Cypripedium calceolus) are all very small and vulnerable and only found on a few locations. However, all species seems to be rather stable over time.  

Monitoring of bird species on the EU Birds Directive annex include 17 breeding species and 39 overwintering species. The population of the breeding species Spotted crake (Porzana porzana), has decreased dramatically since the 19th century, but the population is now the largest since 2011 after years of successful nature restoration projects. Barnacle goose (Branta leucopsis) is monitored as both a breeding species and an overwintering species. Outside the large breeding populations on Saltholm and Peberholm close to Copenhagen, only three pairs of barnacle goose were found in the rest of Denmark in 2016. There is a very large overwintering population of barnacle goose, which have now reached more than 250,000 birds. Whooper swan (Cygnus cygnus) is also a sparse breeding bird and a very numerous overwintering bird, which have now reached more than 60,000 individuals in the winter period. The increase in the population of whooper swan is particularly the volunteer grains on the inland maize and cereal fields.