Andersen, J.M., Boutrup, S., van der Bijl, L., Svendsen, L.M., Bøgestrand, J., Grant, R., Lauridsen, T.L., Ellermann, T., Ærtebjerg, G., Nielsen, K.E., Søgaard, B., Jørgensen, L.F. & Dahlgren, K. Faglig rapport fra DMU nr. 579, 136 s.
Summary
The National Monitoring Programme for the Aquatic and Terrestrial Environments (NOVANA) replaced the former solely aquatic monitoring programme NOVA-2003 on 1 January 2004. With NOVANA, <st1:country-region w:st="on"><st1:place w:st="on">Denmark</st1:place></st1:country-region> initiated integrated systematic monitoring of the aquatic and terrestrial nature and environments.
Wastewater discharges of nitrogen, phosphorus and organic matter and losses of nitrogen from cultivated land have decreased markedly since monitoring began in 1989. The decrease in nutrient discharges has resulted in moderate improvements in environmental conditions in the lakes and marine waters, where the concentration of nitrogen and phosphorus in the water has decreased. This has led to improvements, particularly in the most polluted lakes and fjords. In the more open marine waters, monitoring has only revealed minor improvements in biological conditions – among other reasons because of the level of pollution is lower.
The environmental status of the watercourses has slowly but steadily improved in recent years. The status of the watercourses is mainly determined by the physical conditions and organic matter loading.
In 2004, the currently applicable quality objectives were fulfilled in just over half of the watercourses, in less than 1/3 of the lakes and, as far as concerns the marine waters, only in Skagerrak and in the open parts of the <st1:place w:st="on">North Sea</st1:place> .
A reduction in nitrate concentration has been recorded in the youngest groundwater as a result of reduced leaching of nitrate from cultivated fields.
The 2004 results of the terrestrial natural habitat and species monitoring under NOVANA provide information about the status of the monitored special areas of conservation (Natura 2000 sites), but it is not possible to describe the trend after just one year of monitoring. Once operational quality criteria have been established for terrestrial nature, the monitoring results can be used to determine compliance with the Habitats Directive.
Wastewater
Wastewater discharges from towns, industry, fish farms and sparsely built-up areas account for a considerable proportion of total pollutant input to Danish water bodies. In 2004, wastewater discharges accounted for approx. 10% of the total input of nitrogen to marine waters from the land, approx. 45% of the corresponding phosphorus load and approx. 56% of the degradable organic matter load. These calculations do not take into account the amount converted and retained in watercourses and lakes.
Nitrogen, phosphorus and organic matter
Discharges of nitrogen have decreased by approx. 73% since 1989, mainly due to the fact that nitrogen is removed at municipal wastewater treatment plants. Discharges from industry have also decreased markedly.
Discharges of phosphorus have decreased by 85% since 1989 due to the fact that phosphorus is removed at municipal wastewater treatment plants and from industrial wastewater.
Discharges of organic matter (measured as BOD5) have decreased by 85% since 1989, mainly due to improved biological treatment at municipal wastewater treatment plants but also to a marked decrease in discharges from industry. At the same time, discharges from sparsely built-up areas and freshwater fish farms have also decreased.
The general national reduction targets for wastewater discharges of nitrogen, phosphorus and organic matter have been fulfilled since the mid 1990s. Since then, discharges from wastewater treatment plants have slowly decreased even further. In 2003, biological treatment was established at the last enterprise that discharges large amounts of organic matter via its own industrial outfall.
Hazardous substances
Few hazardous substances have been detected in discharges from municipal wastewater treatment plants, and generally only in low concentrations. In the case of substances for which quality criteria have been set, the concentrations determined are lower than the quality criteria for surface water. The concentrations of heavy metals in the discharged water are also lower than the quality criteria as the wastewater is usually diluted at least 10-fold at the outfall. Many of the hazardous substances are found in the sewage sludge produced during wastewater treatment. A small proportion of the sewage sludge contains hazardous substances in concentrations exceeding the quality criteria for sludge intended for agricultural use. This applies to mercury, nickel, LAS, nonylphenols and DEHP.
Heavy metal and hazardous substance concentrations exceeding the quality criteria for surface water have also been detected in discharges from a few industrial enterprises with separate outfalls.
Input of pollutants via the atmosphere
In 2004, inputs of pollutants to the Danish landmass and water bodies were calculated using a new, improved air pollution model. With this new model the calculated inputs of nitrogen to the landmass and water bodies were 29% and 13% lower, respectively, than those calculated using the model previously employed.
The calculations made with the new model for both 2003 and 2004 show that the input of pollutants via the atmosphere in 2004 was of the same level as in 2003. Thus the calculated nitrogen input to Danish marine waters from the atmosphere in 2004 amounted to approx. 107,000 tonnes N. The corresponding input to the landmass was approx. 68,000 tonnes. The total inputs of nitrogen to the Danish landmass and water bodies from the air have decreased by approx. 20% and 23%, respectively, over the period 1989–2004 due to a reduction in emissions to the atmosphere in both <st1:country-region w:st="on"><st1:place w:st="on">Denmark</st1:place></st1:country-region> and at the European level. The calculated inputs of nitrogen remain high, and the resultant pollution considerably affects the majority of natural countryside and the marine waters.
The inputs and concentrations of heavy metals in 2004 do not differ markedly from those in previous years. Inputs of heavy metals have decreased two- to three-fold over the past 16 years, with the decrease being greatest for lead and cadmium.
Wet deposition of organopollutants in precipitation was included in the monitoring programme for the first time in 2004. Measurements made at Anholt and Sepstrup Sande show that wet deposition of pesticides is greatest at Sepstrup Sande in central <st1:place w:st="on">Jutland</st1:place> . Sepstrup Sande is located in an area with greater precipitation and greater agricultural production than Anholt, an island in the middle of the <st1:place w:st="on">Kattegat</st1:place> .
Agricultural monitoring catchments
Nitrogen
The field nitrogen surplus has decreased by approx. 33% at the national level over the period 1990–2004. The surplus is the difference between the amount of nitrogen applied to the fields and the amount removed in the crops. The decrease is primarily attributable to reduced consumption of commercial fertilizer combined with other changes in production conditions. During that period, annual consumption of commercial fertilizer decreased by approx. 49% from 394,000 tonnes nitrogen to 202,000 tonnes nitrogen. The nitrogen surplus is greatest for livestock holdings, and increases with livestock density. In 2004, the mean surplus was 95 kg N/ha.
Model calculations for the agricultural monitoring catchments have shown that leaching of nitrogen from the agricultural monitoring catchments has decreased by 46% over the period 1990–2004. Measurements have also shown that the concentration of nitrogen in the root zone water has decreased by approx. 34–50%. The concentration of nitrogen in the upper groundwater under sandy soils has decreased, whereas no marked changes have been recorded under clayey soils. The nitrogen concentration in the watercourses draining the agricultural monitoring catchments has decreased by approx. 20–47% over the period 1990–2004.
Phosphorus
The field phosphorus surplus was 10 kg P/ha at the national level in 2004 as compared with approx. 15 kg P/ha in 1990. On average, only livestock holdings exhibited a surplus, whereas crop holdings exhibited a deficit. Over the period 1990–2004, the input of phosphorus to watercourses averaged 0.21–0.51 kg/ha per year in the agricultural monitoring catchments. Thus only a small proportion of the net input is lost from the fields to surface water. The remainder accumulates in the surface soil or leaches to deeper soil layers. In most places the loss of phosphorus to watercourses from fields mainly takes place via surface runoff or drainage water. The loss increases with increasing accumulation of phosphorus in the field. On the other hand, the phosphorus concentration in the water percolating down from the soil to the groundwater is usually low. No change has been detected over the period 1989–2004 in phosphorus loss from cultivated land or in runoff of phosphorus via the watercourses draining the agricultural monitoring catchments.
Pesticides
One of the objectives of the first Action Plan on Pesticides was that total sales of active ingredient should be reduced 50% by 2003 relative to the level in 1981–1985. This objective has been met. Another objective was to reduce application frequency from 2.04 in 2002 to 1.7 in 2009, but this has not yet been met. The application frequency at the national level expresses the number of times the total area of cultivated land could be treated if the approved dose of each pesticide had been applied.
Pesticides or degradation products were detected one or more times in 69% of the investigated filters located in the upper groundwater. The limit value for drinking water was exceeded one or more times in 25% of the filters located in the agricultural monitoring catchments. Four of the most commonly used pesticides are among those most frequently detected in the near-surface groundwater in the agricultural monitoring catchments over the period 1993–2004, namely bentazon, glyphosate, metamitron and MCPA.
Groundwater
The available groundwater resource in <st1:country-region w:st="on"><st1:place w:st="on">Denmark</st1:place></st1:country-region> is approx. 1,000 million m3 per year. At the national level there is sufficient water to meet requirements for the water supply, which has fluctuated around 600–700 million m3 per year in recent years. Around the large towns, however, the groundwater resource is too small to meet requirements without markedly affecting watercourses and wetlands.
The limit value for nitrate in drinking water (50 mg nitrate/l) is met by approx. 99% of the water utilized for the drinking water supply. Of the uppermost, newly formed groundwater, about half contains more nitrate than the limit value, although the variation is considerable. The nitrate concentration in the uppermost, newly formed groundwater in sandy areas has decreased in recent years. The decrease is attributable to the measures implemented to reduce leaching of nitrate from cultivated land following adoption of Action Plan on the Aquatic Environment I in 1987. The water in the remaining groundwater bodies is generally formed prior to 1987 and hence is unaffected by the initiatives implemented in connection with the action plan.
The limit value for phosphorus in drinking water is exceeded in the groundwater at approx. 20% of all water supply wells. This is of no great importance, however, as the phosphorus is removed at the waterworks. The measured phosphorus concentration in the groundwater largely reflects the natural phosphorus concentration in the groundwater. The phosphorus concentration is elevated in a small proportion of the very uppermost groundwater, however.
The decline in pesticide detection frequency in water supply wells seen in the preceding year continued in 2004. One of the main reasons for the lower detection frequency is closure of pesticide-contaminated wells. In contrast, the frequency of pesticide detection at the groundwater monitoring sites has increased for concentrations both below and above the limit value for drinking water.
Watercourses
Nutrients
The concentration and transport of nitrogen is generally decreasing in the watercourses that drain cultivated catchments and/or receive large amounts of wastewater. For all watercourses as a whole, the concentration of nitrogen in the water has decreased by an average of 29% since 1989 while the transport of nitrogen has decreased by 34%. The decrease is attributable to a decrease in nitrate leaching from cultivated land and to the fact that nitrogen removal is now carried out at all wastewater treatment plants exceeding 5,000 PE.
The concentration and transport of phosphorus in watercourses receiving wastewater discharges decreased markedly during the first half of the 1990s. It is only slightly higher than that in watercourses draining the agricultural monitoring catchments. The concentration of phosphorus in watercourses has decreased by an average of 43% since 1989, while the transport of phosphorus has decreased by 39%. The decrease is attributable to the upgrading of wastewater treatment plants with phosphorus removal, including at small treatment plants to protect local recipients. The decrease during the early 1990s was a continuation of the decrease that started when phosphorus removal at wastewater treatment plants was introduced around 1980.
Pesticides and heavy metals
The concentrations of heavy metals and pesticides are measured in five watercourses. The heavy metals concentrations recorded in 2004 were considerably lower than the quality criteria for surface waters. In a few cases the concentrations of lead and copper exceeded the quality criteria.
The pesticide monitoring encompasses 10 herbicides and eight of their degradation products. The majority of the samples analysed were found to contain one or more pesticides. Three of the most commonly used herbicides are frequently detected in both watercourses and beneath the fields in the agricultural monitoring catchments, namely glyphosate, MCPA and terbutylazine. Three herbicides whose use is now prohibited are detected in a large proportion of the samples, namely trichloroacetic acid (55%), DNOC (15%) and atrazine (8%). Quality criteria have not been set for the substances analysed for.
Compliance with objectives
The ecological status of watercourses is assessed from the presence of macroinvertebrates. The monitoring results show that the ecological status of Danish watercourses has gradually improved since 1994. This is due to improved wastewater treatment and more environmentally sound watercourse maintenance. Nationwide, 58% of the investigated watercourses met their quality objective in 2004. On Bornholm, all six monitored watercourses met their quality objective as compared with 61% on Funen, 62% in Jutland and only 34% on the island part of Denmark east of the Great Belt. Compliance with objectives is best (88%) for the watercourses with the highest quality objective.
Lakes
Nutrients
The monitoring programme was modified in 2004 and now encompasses extensive monitoring of 1,074 lakes and ponds with a limited programme every 3rd or 6th year. At the same time the intensive monitoring has been cut back from 31 to 23 lakes, of which 20 have been included in the programme since 1989. These changes will ensure that knowledge is procured over the next six years about the status of a large representative part of Danish lakes.
The results from the lakes that were intensively monitored in 2004 show that the environmental status has improved since 1989 due to the decrease in phosphorus loading. The latter varies considerably from lake to lake depending on the degree to which wastewater discharges in the lake catchment have been reduced. On average, the phosphorus concentration in the lakes has almost halved since 1989. Of the phosphorus input to lakes in 2004, approx. 34% derived from wastewater, approx. 44% from cultivation of the land in the catchment and the remaining approx. 22% was natural background loading.
Nitrogen loading and lake water nitrogen concentration have decreased due to the reduction in leaching of nitrate from cultivated land.
In approximately half of the intensively monitored lakes the nutrient concentration in the lake water has decreased. In approx. 1/3 of these lakes this has led to a reduction in the amount of phytoplankton.
Compliance with objectives
Even though the environmental status of the lakes has improved, the current environmental objectives were only met by five of the 23 intensively monitored lakes in 2004. The environmental status of some of the lakes will probably improve further when phosphorus release from the sediment has tailed off. This phosphorus derives from earlier wastewater inputs to the lakes.
The nutrient and algae concentrations in the large number of extensively monitored lakes are higher than in the intensively monitored lakes. As a consequence, the environmental status of Danish lakes as a whole is generally poorer than that of the intensively monitored lakes. One reason for this could be that the extensively monitored lakes are smaller and shallower than the intensively monitored lakes.
Marine waters
Nutrients and eutrophication
The concentrations of inorganic nitrogen and phosphorus have roughly halved in fjords/coastal waters since 1989. This is mainly due to the fact that phosphorus is removed from the wastewater and that leaching of nitrate from cultivated land has decreased. In the open marine waters the change in concentration is less. Due to the lower nutrient concentration, the amount of algae in the marine waters has decreased and Secchi depth has increased since the 1980s, algal production now being more limited by a lack of nitrogen and/or phosphorus than was previously the case.
In 2004 the ecological status of the open water masses was generally poorer than in the preceding five years. Among other reasons this was due to an algal bloom (silicoflagellates) in the <st1:place w:st="on"><st1:PlaceName w:st="on">Belt</st1:PlaceName> <st1:PlaceType w:st="on">Sea</st1:PlaceType></st1:place> in April–June 2004 that probably resulted from the input of nutrients from the bottom water. The generally poorer ecological status in 2004 could also be an after-effect of the extraordinarily great oxygen deficit in 2002 combined with the effects of the climate and sea currents. Oxygen deficit was less extensive in 2004 and lasted a shorter time than in the two preceding years. The oxygen concentration in the bottom water of the fjords/coastal waters has generally been low during the past six years.
No major changes occurred in the abundance and depth distribution of submerged macrophytes in the coastal waters except for a decrease in eelgrass coverage and depth distribution in the innermost part of the fjords. In contrast, the density of benthic invertebrates and the number of species detected in each sediment sample in the inner open marine waters have declined steadily since 1994. Pollution-sensitive species of benthic invertebrates have declined more than the more pollution-tolerant species. In the fjords/coastal waters the decline was due to the extreme oxygen deficit in 2002.
Hazardous substances
In most areas, PCB has been detected in concentrations that could possibly be ecotoxic. Brominated flame retardants were included in the monitoring for the first time in 2004. They were detected in 75% of the samples, with the highest levels being recorded in Vejle Fjord and Øresund, although in much lower concentrations than PCB.
Tributyl tin (TBT) was generally detected in lower concentrations in 2004 than in 2003. In all the areas investigated the concentrations were such as to pose a great risk of causing adverse effects in animals. The concentrations were highest in Randers Fjord and in the fjords of Funen, where there is much shipping and related activities. The use of TBT in antifouling paints is being phased out.
Evidence indicates that eelpout and mussels are affected by hazardous substances in certain coastal waters.
Compliance with objectives
The current quality objective that the flora and fauna should at most be only slightly affected by man’s activities is generally considered to be met in the Skagerrak and in the open parts of the North Sea and close to being met in the open northern and central Kattegat. In the remaining Danish marine waters the quality objective is not met, primarily due to nutrient loading. In certain areas compliance with objectives is hindered by high concentrations of TBT, organochlorines, PAH or heavy metals.
Terrestrial natural habitats
Monitoring of terrestrial natural habitats was incorporated into the national monitoring programme from 2004 onwards. The monitoring carried out in 2004 concentrated on areas designated as Special Areas of Conservation (Natura 2000 sites) pursuant to the Habitats Directive. One of the main objectives was to assess <st1:country-region w:st="on"><st1:place w:st="on">Denmark</st1:place></st1:country-region> ’s compliance with the directive.
Development of the majority of Danish terrestrial natural habitats has been governed by a combination of the natural conditions and extensive exploitation of the areas. The monitored areas have been extensively managed as heaths, dry grasslands and meadows. Only a small proportion of the natural habitats, e.g. raised bogs and dunes, have arisen independently of man’s activities. The main reasons for the changes in the natural habitats are changes in the management of the land, including drainage and fertilization, and the input via the air of pollutants derived from combustion processes and agriculture. The input of nitrogen from the air favours the nutrient-demanding species at the cost of the vegetation that is characteristic for nutrient-poor natural habitats. The cessation of grazing often results in the habitats becoming overgrown with trees and bushes.
2004 was the first year in which terrestrial natural habitats were included in the monitoring programme. The results provide a foundation for assessing the environmental status of the natural habitats that are encompassed by the Habitats Directive. It is not possible to assess whether their status complies with the objectives, however, as specific operational criteria for favourable conservation status have not yet been set.
Species monitoring
Species monitoring was incorporated into the national monitoring programme from 2004 onwards. The monitoring focuses on the occurrence of selected plant and animal species encompassed by the Habitats Directive and breeding birds encompassed by the Birds Directive, as well as species of which more than 20% of the global population occurs in Denmark (vascular plants, moths and regularly occurring migratory birds). One of the main aims of the monitoring is to assess whether <st1:country-region w:st="on"><st1:place w:st="on">Denmark</st1:place></st1:country-region> meets its obligations under the Habitats Directive and Birds Directive.
Some species have been monitored for many years under other programmes. By way of example, the main conclusions are presented here for four species: Otter, floating water-plantain, marsh fritillary and greylag goose.
Otter range and population size have increased markedly since 1984–86. The positive trend in the population is due to improvements in habitats, the establishment of fauna passages at roads and obligatory use of otter guards on eel traps.
The floating water-plantain grows in ponds and watercourses with slowly flowing or stagnant water at a few localities in western <st1:place w:st="on">Jutland</st1:place> . No marked changes in occurrence have been detected since 2002.
The marsh fritillary butterfly lives on humid heaths and unfertilized meadows on infertile soil vegetated with their preferred host plant, the devil’s-bit scabious. It was only detected in northern <st1:place w:st="on">Jutland</st1:place> in 2004, and there are no signs of marked changes in its occurrence in recent years.
In connection with an international census, greylag geese have been counted each year in September at selected localities since 1984. The number of greylag geese has increased steadily over the period, although most markedly since 1995.
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