Highlights of NERI’s activities

NERI undertakes research, monitoring and scientific consultancy work relating to nature and the environment. The various aspects of NERI’s work are examined in the sections below. Emphasis is placed on describing both the results of the activities undertaken, and the perspectives for the coming years’ work.

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Reducing nitrogen loading from agricultural sources
The marine environment - improvement in sight
Nitrogen removal in coastal waters
Utilization of livestock manure
Modelling the fate of pesticides
Genetically modified plants in the environment
Biotechnology in agriculture

NERI’s work in this area encompasses: nutrients, pesticides, new agricultural practices, and the effects of introduced microorganisms and genetically modified plants.

Environmental impact of agriculture

Reducing nitrogen loading from agricultural sources

By far the majority of nitrogen input to the aquatic environment derives from agriculture. In order to limit nitrogen loading of the aquatic environment from agricultural sources, Parliament adopted the Action Plan on the Aquatic Environment II (VMP II) in spring 1998. The parliamentary agreement on VMP II also commits the Government to draw up an action plan to reduce nitrogen emissions to the air as ammonia. In both cases, NERI and the Danish Institute of Agricultural Sciences were jointly responsible for providing the scientific foundation for the action plans.

High concentrations of nitrate-nitrogen render the groundwater unsuitable as drinking water. In our estuarine fjords and marine waters, excess nitrate results in algal blooms and subsequent oxygen deficit, which changes the natural flora and fauna. This is basically the reason why the 1987 Action Plan on the Aquatic Environment (VMP I) required the agricultural sector to reduce nitrogen loading from fields by 100,000 tonnes.

While wastewater treatment plants and industry have largely met the goals stipulated in the action plans for both phosphorus and nitrogen, it has been clear for some years that the agricultural sector would not be able to reduce nitrogen loading by 100,000 tonnes. The political agreement on the second Action Plan on the Aquatic Environment (VMP II) is based on estimates that the measures hitherto adopted will reduce nitrogen loading from agricultural sources by approx. 63,000 tonnes, the goal thus being that VMP II should reduce loading by the remaining 37,000 tonnes nitrogen.

VMP II will eventually reduce the nitrate concentration of the groundwater. Moreover, wetlands will be reestablished, and the state of the environment will be improved - especially in the estuarine fjords and coastal waters. VMP II will be gradually implemented up to the year 2003, but a number of years will pass before the full effect is attained.

In an international context, VMP II is clearly the most ambitious initiative to reduce nitrogen loading of the aquatic environment. The EU Commission has just acknowledged that with VMP II, Denmark is the first country to essentially comply with the EU Nitrates Directive. In its official letter, the Commission emphasizes the fact that the Action Plan was accompanied by an overall scientific evaluation prepared by NERI in collaboration with the Danish Institute of Agricultural Sciences.

As part of VMP II, agreement was reached that the Government should draw up a proposal for an action plan to reduce agricultural emissions of ammonia to the air. NERI and the Danish Institute of Agricultural Sciences have just completed the reports providing the scientific foundation for the proposed plan. The conclusion is that nitrogen input as ammonia poses a significant environmental problem on the land, where many of the Danish forests and natural ecosystems currently receive more than they can tolerate. A few of the Danish oligotrophic lakes are threatened and the marine environment is also affected, even though other nitrogen sources are of greater significance in this case.





Foto: National Forest and Nature Agency, Bent Lauge Madsen





Foto: National Forest and Nature Agency, Bent Lauge Madsen

Fhoto: National Forest and Nature Agency, Bent Lauge Madsen

Re-establishment of wet meadows is an important measure in the new Action Plan on the Aquatic Environment (VMP II). The aim is that the wet meadows should help reduce nitrogen loading of the aquatic environment. Up to the year 2003, 16,000 ha of wetlands are to be re-established. This is expected to result in the removal of 5,600 tonnes nitrogen per year.

In the coming years, monitoring of nitrogen loading of the aquatic environment from agricultural sources will be continued in a revised nationwide monitoring programme for the period 1998-2003, NOVA 2003. A special programme has been agreed upon to follow the effects of the new wetlands to be established under VMP II. The results will be incorporated in the assessments of the effects of VMP II to be undertaken by NERI and the Danish Institute of Agricultural Sciences in the years 2000 and 2003 in accordance with the parliamentary agreement on VMP II.

The marine environment - improvement in sight

Nitrogen loading of the sea from the Danish land mass has fallen approx. 15% since the 1980s. This is primarily due to improved wastewater treatment, as well as improved utilization of the nitrogen content of livestock manure and reduced consumption of commercial fertilizer. The actual level of nitrogen loading also depends on freshwater runoff, however, and thus varies considerably from year to year. Results from the very dry years of 1996 and 1997 indicate that when nitrogen loading is reduced to the level stipulated in the Action Plan on the Aquatic Environment, the state of the aquatic environment will markedly improve, not only in the estuarine fjords, but also in the open marine waters.

The results of the regular monitoring undertaken by the Counties and NERI show that the concentration of phosphorus in the sea has fallen over the period 1989-97 in step with improved treatment of wastewater. There is also a tendency towards decreasing nitrogen concentrations in the sea corresponding to the variation in freshwater runoff, the concentration being particularly low in 1996 and 1997.

Our enclosed estuarine fjords are of considerable significance in determining how great a part of nutrient runoff from the land will reach the open marine waters. In the case of nitrogen, net removal takes place in the fjords. In fjords with a long hydraulic retention time such as Limfjorden, Ringkjøbing Fjord, Mariager Fjord and Nissum Fjord, the reduction averaged about 40% over the period 1990-96. In the case of phosphorus, the opposite is true. Phosphorus has accumulated in the fjord sediment over the years, and now that phosphorus loading has been reduced to around 20% of the level in the mid 1980s, net export of phosphorus is taking place from the fjord sediment to the open marine waters. In the Kattegat, phosphorus input from the fjords is so great that no overall reduction in phosphorus loading is apparent.






Photo: NERI






Photo: NERI






Photo: NERI

NERI has strengthened cooperation with the Counties on monitoring of our estuarine fjords and marine waters by holding more frequent meetings, drawing up technical guidelines and starting a quarterly newsletter on marine monitoring.

The oxygen content of the sea is normally lowest in August-October. Over the period 1989-97, the concentration of oxygen increased slightly in the southern Kattegat and Øresund. This was not the case in the southern Belt Sea, where the oxygen content increased in the spring. In 1998, oxygen conditions again deteriorated in the southern Kattegat, Øresund and Belt Sea in accordance with the higher freshwater runoff and nitrogen loading that year. Nevertheless, this does not change the fact that the general picture of the situation is one of slight improvement.

Model calculations show that a permanent reduction in nitrogen loading of the magnitude assumed in the Action Plan on the Aquatic Environment will markedly improve oxygen conditions in the inner Danish marine waters. This will not completely hinder the occurrence of oxygen deficit, especially in unfavourable years, but it will be less frequent and widespread than previously.

Life in the sea has benefited from the trend in the nutrient and oxygen content of the water. Biologists have detected a decrease in the amount of phytoplankton and zooplankton. This means that less oxygen is consumed to degrade dead algae on the sea floor and the water becomes more transparent, enhancing light penetration. As a consequence, eelgrass has slowly started to recolonize.

In the coming years, NERI will continue the cooperation with the Counties on monitoring of the marine environment and will expand the use of models to assess relationships between input and transport of nutrients and life in the sea.

Nitrogen removal in coastal waters

We have long known that bacteria are able to remove nitrogen. Scientists are now investigating how much nitrogen bacteria remove in Europe’s coastal waters - and what determines the magnitude of this nitrogen removal. NERI coordinates an EU-financed project aimed at elucidating the factors that control the work done by these useful bacteria.

Too little and too much. That is the crux of the nitrogen problem. On the fields, farmers want to apply nitrogen fertilizer to promote crop growth - in the aquatic environment, the excess nitrogen that leaches from agricultural land results in unintended eutrophication. It is this diffuse loading from the fields that Danish politicians try to reduce through the Action Plan on the Aquatic Environment II.

Luckily, however, part of this nitrogen is removed in our estuarine fjords and coastal waters, thereby reducing the negative effects that the nitrogen loss from agricultural land would otherwise have on the marine environment. It is bacteria in the marine sediment that remove the nitrogen, and their activity is markedly affected by such factors as the benthic vegetation. In step with the anticipated increase in the transparency of the water as a result of the planned reductions in nitrogen loading, light will be able to penetrate to the sea bed at increasing depths. Benthic macrophytes will consequently colonize, thereby also affecting bacterial nitrogen removal.




Photo: NERI






Photo: NERI

Photo: Peter Bondo Christensen, NERI

NERI is heading an EU project aimed at determining how much nitrogen is removed in coastal waters. It is bacteria in the marine sediment that remove the nitrogen, and their activity is markedly affected by the benthic macrophytes.

NERI is coordinating an EU project aimed at providing new insight into nitrogen removal in the coastal waters. The project involves participants from Portugal, Italy, England, Sweden and Denmark. The scientists started in 1996 by drawing up a joint experimental protocol so as to ensure that the results from all the laboratories involved were comparable. Nitrogen removal was then followed monthly at a total of 22 field sites selected to represent various types of vegetation, climate and tidal conditions.

Based on the results of the monthly measurements, a number of hypotheses for nitrogen removal were put forward and subsequently tested by joint field campaigns in Italy, Portugal and Sweden. One particular hypothesis concerning inhibition of nitrogen removal (denitrification) by benthic macrophytes was investigated in detail. The preliminary results confirm that the plants inhibit denitrification. The results thus contribute to a greater understanding of the regulation of nitrogen removal.

In the remaining part of the project, the scientists will collate all the measurements in a database in order to ascertain how the removal of nitrogen varies in different European water bodies. The objective is to establish a general model incorporating the factors that control nitrogen removal. This will enable nitrogen removal in a given marine water to be determined on the basis of simple measurements measurements that in Denmark, for example, are part of the Counties’ routine environmental monitoring of the estuarine fjords and coastal waters.

The project will be completed during 1999. Further information is available on NERI’s Internet home-page at address:http://www.NERI.dk/LakeandEstuarineEcology/nice

Relationship between the applied and recommended levels of nitrogen at field level. Each column represents 10% of the area. Data from the 6 agricultural catchments included in the Nationwide Monitoring Programme under the Action Plan on the Aquatic Environment. The fertilizer value of the livestock manure is incorporated in the nitrogen fertilizer at field level.

Utilization of livestock manure

In recent years, farmers have reduced consumption of commercial fertilizer in step with increasing requirements on utilization of the nitrogen content of livestock manure. A study of the farms included in the Nationwide Monitoring Programme under the Action Plan on the Aquatic Environment shows that one or more fields are overfertilized on over half of the farms - especially those with a large livestock herd. In part this is due to the fact that it is expensive to transport the manure to those fields that lie furthest away from the manure stores. Conversely, there are also fields that receive less than the recommended level of fertilizer.

The study is based on interviews with the farmers. Just over 90% of the fields lay within a radius of 2 km from the manure stores. Of these, just over half were fertilized with livestock manure while those fields further than 2 km from the stores more rarely received livestock manure. Thus at a distance of 2-3 km, approx. 40% of the fields received manure, while only 10-20% of the fields lying more than 3 km from the manure stores received livestock manure.

Photo: CDanmark

Photo:  Anna Bodil Hald, NERI

NERI has also investigated the costs of applying slurry to fields lying at different distances from the slurry tanks. The study shows that the cost doubles from DKK 5-6 to DKK 10–12 per kg effective nitrogen when the distance increases from approx. 100 metres to approx. 5 km for cattle manure and to 8 km for pig manure, these being the maximum distances manure was moved on the farms studied. These costs can be compared with the retail price of commercial fertilizer, currently DKK 4 per kg nitrogen.

NERI has therefore examined the possibilities to sway farmers towards more optimal distribution of fertilizer. The study was undertaken in collaboration with the Danish Institute of Agricultural and Fisheries Economics. Among other things, the results indicate that measures should be directed towards the use of livestock manure if fertilizer consumption is to be reduced effectively on livestock farms. This is because commercial fertilizer only accounts for about one quarter of fertilizer consumption on pig farms. Changes in the price of commercial fertilizer or measures directed towards the consumption of commercial fertilizer will therefore have little major effect. The situation will be different in the case of changes in total fertilizer consumption at farm level, for which limits are already in force.

In the coming years, NERI will continue to investigate farmers’ fertilization practice as part of the monitoring activities under the Action Plan on the Aquatic Environment II. NERI will also continue the development of models to calculate the environmental and economic consequences of agricultural and environmental policy measures. In addition to continual improvement of the models, NERI scientists will also include new aspects in the calculations, e.g. phosphorus fertilizer and pesticides.

Modelling the fate of pesticides

NERI has developed a model describing the fate of certain pesticides in small ponds. More pesticides will be included in the coming years. The project is part of a major modelling project aimed at describing the dispersal of pesticides in the environment and is used by the Danish EPA as a tool in its work on regulating pesticides.

NERI has used a system of four artificial ponds to investigate what happens to pesticides in field ponds. In the first instance, four different pyrethroid insecticides were investigated: Deltamethrin, permethrin, esfenvalerat and fenpropathrin, all of which are relatively fat-soluble (low solubility in water).

The insecticides were sprayed on the water surface, and NERI scientists then followed the concentration in the ultrathin surface layer, in the water column itself, and in the sediment.


























Outline of the pond model. The mechanisms of greatest significance for the fate of pesticides in ponds are indicated on the figure.

Testing of mathematical models has provided a number of valuable results. In the case of the water column/sediment system, the most convincing model comprised diffusion, binding to particles and degradation in the sediment. This means that the substances were accumulated in the uppermost layer of the sediment.

On the basis of the experiments, NERI scientists have established a general mathematical model describing the presence of the substances in the water column and sediment, as well as their transport between these two media. The model predicts that the concentration in the water column will largely be proportional to the input to the surface and virtually independent of the water depth. This is primarily attributable to the fact that the substances disappear from the water column within just a few days. The model thus predicts that all fat-soluble substances that are rapidly taken up by the sediment will behave in this way. The measurements showed a marked tendency for pyrethroids to accumulate in the surface microlayer. This is probably due to their low water solubility. Only a small part of the total amount of insecticide remained in the surface microlayer, though, by far the majority being mixed into the water column within a few hours after application.

The study not only enhances our knowledge of the fate of pesticides in ponds, but can also be used to design new experiments with other pesticides. Besides the transport of substances to and from the surface microlayer, there is a particular need to be able to distinguish between the significance of diffusion and adsorption to particles in the sediment.The study is reported in two reports published by the Danish EPA and in a recently published issue of NERI’s popular science theme report series. NERI also participated actively in the preparation of the report recently put before Parliament on the economic and environmental conse-quences of a complete or partial ban on the use of pesticides, the so-called Bichel Committee Report.

In the coming years, NERI will continue development of the pond model, in part to describe the missing steps in the model, in part to extend the model to also describe the fate of other types of pesticide. In addition, NERI will work on developing models of pesticide transport and degradation in watercourses, lakes, the air, etc.

Genetically modified plants in the environment

A large number of genetically modified crops, vegetables, flowers and trees are on their way out to the fields. NERI is examining the possible environmental consequences.

The new agreement with industry and agriculture on genetically modified crops in Denmark contains a special section on openness and dialogue on the use of genetically modified crops. To support this dialogue, NERI has recently published a report on genetically modified plants in its popular science theme report series.

The report describes how genetic engineering differs from traditional breeding. In addition, it describes the properties that scientists are trying to alter and what risks genetically modified plants entail. The authors discuss resistance to herbicides, pests and disease, as well as tolerance to salt, drought and cold. Moreover, they describe how the authorities assess the risks of genetically modified plants within the areas ecology, health and agriculture.

The environmental effects of a genetically modified plant depend on the plant’s characteristics and the genes introduced. The ability to compete with other plants is particularly important. Once the genetically modified plant is established, it can affect the flora and other organisms in the food chain.

Genetically modified plants can spread directly in the environment via seeds, rhizomes, etc., or the genes can spread to related species. The report describes how the environment can be affected. In this context, the authors particularly emphasize the stresstolerant plants now being designed, i.e. plants that have been genetically modified to be tolerant to drought, salinity, etc. Such plants will have particularly good possibilities to establish themselves outside the farmer’s fields in dry or salty areas.

NERI is working on developing methods and procuring knowledge to support and develop the assessment of the effects of genetically modified plants in nature. It is important that the plants are assessed thoroughly so that harm to the environment can be avoided.

NERI’s knowledge in this field is regularly exploited in national and international expert committees working on risk assessment of genetically modified plants. Moreover, NERI co-arranged an international conference on the topic in 1998.

In the coming years, NERI will continue the work under the Danish Environmental Research Programme, with the emphasis being on the ecological effects of the cultivation of genetically modified plants resistant to fungal infections. Work will also be undertaken on insectresistant plants and plants given so-called allelopathic action, i.e. the crop can fight weeds in the field by secreting substances that are toxic to weeds. Within the next decade, the first genetically modified trees will appear in Denmark. In this context, NERI is participating in a network in which a number of projects will be initiated to investigate the special problems that can arise when genetically modified trees are released into the environment.

Biotechnology in agriculture

The effects of the use of modern biotechnology in agriculture are now being examined. NERI is investigating whether the use of microbial -pesticides will be able to change the composition and activity of the soil microflora.

Microbial pest control will become an important alternative to chemical pest control. NERI expects that new products will be placed on the market in the coming years, and that their use will become common practice in agriculture and market gardening. It is therefore important to elucidate the environmental consequences before the new agents enter into use. NERI is therefore investigating whether the new agents can have unintended effects on soil bacteria and fungi.

In the first instance, NERI scientists have examined the effects of two possible pesticides, both of which can combat fungal infections in the soil, namely strains of the bacteria Pseudomonas fluorescens and Bacillus cereus. The preliminary results show that the two bacteria do not affect the microflora’s total respiration but that an effect becomes apparent upon detailed examination of the ability of the microflora to metabolize 95 specific carbon compounds. In order to more closely examine the changes in the soil bacterial community, NERI scientists tested the capacity of the two strains to inhibit a total of 4,500 bacterial strains from an organically farmed barley field. An effect was also found here in that the two bacteria inhibited the growth of 2-3% of the bacteria derived from the soil and 5-6% of those derived from the root zone. The scientists will now investigate the environmental significance of the fact that a few bacteria can be selectively inhibited as a result of the use of microbial pesticides.

In the coming years, NERI scientists will examine the mechanisms behind this growthinhibiting effect. NERI will also investigate what effect the use of Pseudomonas fluorescens to coat seeds has on the naturally occurring bacteria in the root zone and the surrounding soil. The results of the project are expected to comprise an important tool for future risk assessment of new microbial pesticides. The project will be completed in the year 2000 and is being undertaken within the framework of a centre headed by NERI under the Danish Environmental Research Programme.

Photo: Jens C. Pedersen, NERI

Photo: Klaus Holsting

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