[] TL: Nutrient conditions, eutrophication and its effects in the Baltic Sea (GP) SO: Report prepared for Greenpeace International DT: August 1990 Keywords: oceans baltic sea greenpeace gp reports / [part 1 of 5] Contents Abstract 2 Nutrient conditions in the Baltic Sea area 3 Definition 3 Unique conditions 3 Nutrient conditions 3 Nutrient sources 4 Limiting factors 5 Effects 6 Effects on phytoplankton 7 Effects on macroalgae in the coastal zone 7 Effects on oxygen content 9 Counteraction 10 Is a 50 % reduction enough? 11 Annex 1 Water protection measures in Estonia 14 Water protection measures in Latvia and Lithuania 14 Excerpts from the Danish Water Protection Programme, dated Jan. and April 1987 15 Excerpts from the Finnish Water Protection Programme to 1995 16 Excerpts from Water Protection Plan for the Federal Republic of Germany 18 Annex 2 The Baltic Marine Biologists: Statement about drastic changes in the Arcona Sea 1989 20 References 21 Figures 25 NUTRIENT CONDITIONS, EUTROPHICATION AND ITS EFFECTS IN THE BALTIC SEA ABSTRACT The Baltic Sea area, as defined by the statutes of the Helsinki convention is severely affected by eutrophication (increased levels of the nutrient salts, nitrogen and phosphorus). The level of phosphorus in the surface water in the central Baltic Proper has increased by a factor 8, and for nitrogen by factor 4 in twenty five years. For the Kattegat area, the increase may be even larger. A reduction of at least 50 % or even up to 70-80 % have been proposed by some experts. When estimating the nutrient balance of the Baltic Sea area the balance between high fishproduction and fishcatch must be considered. The biological effects are manifested in an increased production of organic matter by phytoplankton (plankton blooms, algal blooms) and macroalgae. The sedimentation of organic matter to the bottom has resulted in reduced oxygen level or completely anoxic conditions in the bottom water. Anoxic conditions are now found at approx. 100 000 km2, or 30% of the bottom surface in the Baltic Sea area. Vast areas of anoxic bottoms, bottoms with with very low oxygen content, are now frequently found in the south part of Kaftegat, in the north part of Oresund and in the Kiel Bight adjacent Danish coastal waters. This is now a serious threat to the whole Baltic marine environment and to the important cod fishery, as the reproduction areas are destroyed. The only counter action is a rapid reduction of nitrogen and phosphorus in the whole area. The decisions, by the Baltic countries, to reduce the nutrient outflow by 50 % to 1995, may not be enough, and can hardly be implemented. The nutrient load is, to a large extent, of antropogenic origin. NUTRIENT CONDITIONS IN THE BALTIC SEA Definition According to the definition the Baltic area consists of the following areas: The Bothnian Bay, Bothnian Sea, Aland Sea, the Gulf of Finland, the Baltic Proper, the Belt Sea including the Oresund (the Sound) and Kattegat to the line Gothenburg - Skagen (map 1). Unique conditions The area, which is the largest brackish area in the world, is characterized by a unique salinity gradient, from the Kaftegat to the Bothnian Bay. The surface water salinity has its maximum in the northern part of the Kattegat, with about 25 - 30 o/oo (parts per thousand), and is then slowly decreasing to about 2 o/oo in the northern most part of the Bothnian Bay. Along the coast of Kattegat, and especially in the Belt area, the salinity gradient is very unstable and characterized by a large daily, seasonal and long term variation. Beside the salinity gradient there exists a marked stratification in salinity, with lower salinity in the surface water, and a higher salinity in the bottom water. The halocline in the Belt Sea and Kaftegat area is normally to be found at about 10 - 15 m in depths, and in the Baltic Proper normally at 80 - 100 m in depths. One factor, which is very important for creating these phenomena, are the thresholds in the Belt area. In Oresund, between Malmo and Copenhagen, the sill depth is not more than 8 m, and in the Great Belt the sill depth is about 17 m. The salinity situation is affecting both the organisms in the area, as well as the bottom conditions in the Kattegat, the Belt area and in the Baltic Proper. The salinity has a very strong influence on the species distribution along the gradient. The number of species are very much decreased. In the Bothnian Bay only a few percent of all the marine species can survive. Beside the number of species, their size is reduced, their vertical distribution is changed, the reproduction is disturbed and the metabolism rate is changed, etc. Nutrient conditions The whole area is affected by elevated levels of nutrient salts, e.g. nitrogenand phosphorus, "eutrophication". During the last 25 years the nitratenitrogen, in the surface water of central parts of the Baltic Proper, on average, has increased from I to 4 /umol/l, thus a factor four (4), and the phosphate-phosphorus from 0.1 to 0.7 /umol/l, Nehring 1984, fig. 1. The concentration of nutrients have increased in almost all parts of the Baltic, with the exception of the Bothnian Bay, Wulff & Rahm (1 988). The corresponding increase in the Belt area and in the Kaftegat is 6 resp. 1 0 times, Anon (1 988). 3 From Nehfing (1988) a slight decrease in the nitrogen- and phosphorus values in the central Baltic can be found. Whether this is due to a real reduction of the input, or just some inter-annual variation due to other factors, is too early to say, fig. 2. Nutrient sources The main sources for the increased nutrient content are domestic- and industrial sewage, land run-off, atmospheric downfall, nitrogen fixation and fishfarming. According to Larsson et al (1985) the total annual amount of nitrogen and phosphorus brought into the entire Baltic is about 1 million tons resp. 70 000 tons, tab. 1. Wulff & Rahm (1988) have revised these figures, and got about the same results; a difference of about 10 % was found. Tab. 1 Total input of nitrogen and phosphorus and BOD (Biological Oxygen Demand) in tons/year. Larsson et al 1985. BOD TOT-P TOT-N 5/7 Bothnian Bay 179.300 3.400 60.100 Bothnian Sea 231.400 3.800 85.000 Gulf of Finland 330.100 5.000 75.000 Baltic Proper Municipal 109.600 12.0000 54.900 Industrial 80.800 600 5.700 Rivers 592.400 40.800 466.600 Atmosphere - 9.000 260.000 N2-fixation - - 130.000 Total 782.800 62.400 917.200 Oresund and Balt Sea 174.400 7.700 65.800 Baltic Sea total 1.698.000 82.300 1.203.600 The urban and industrial waste water contribute only to about 20 % of the total phosphorus input and 6 % of the total nitrogen input. The major sources are land run-off and atmospheric downfall. The latter consists of both dry and wet deposition. A recent estimation by Iversen et al (1989) found the total deposition to the Baltic Sea, in 1988, to be 315 000 tons. This originates from about 20 different countries. One also has to bear in mind that the nitrogen from atmospheric downfall over the land surface, to a larger or smaller extent, sooner or later is transported from the soil to rivulets and rivers, to lakes and to the sea. As the drainage area of the Baltic Sea is at least three times bigger than the Baltic Sea, even a small leakage/ha will end up with a substantial contribution to the eutrophication. The downfall of nitrogen has been estimated to approx. 60 kg N/ha and year in the Netherlands, in Denmark and the south part of Sweden to 30-40 kg, and in the north part of Sweden and Finland to about 8-1 0 kg/ha and year. The agriculture in all the Baltic countries are also contributing to the excess of nutrients by land run-off, both in form of high doses of fertilizers and from extensive animal farming. Nitrogen fixation in the sea is made by blue-green algae. In the Baltic Proper and partly in the Belt area, it is mostly done by Nodularia spumigena. In condition with low nitrogen content in the water, and some surplus of phosphorus, the algae starts to take up atmospheric nitrogen and include it in the cell material. The nitrogen fixation takes place in the warmest part of the summer, in July, August and sometimes the first week of September. During optimal conditions the uptake rate can be several mg nitrogen/m2 and hour. When the algae are decaying, ammonium nitrogen is released to the water, and can be utilized by other algae. The fishfarming in the Baltic Sea is still of little importance. Probably a maximum of 10 - 15 000 tons are produced annually. The phosphorus contribution is maybe 150 tons/year and for nitrogen about 1 000 tons. For the whole area the effects are negligible, though in some local areas, especially in the Aland area, the effects are quite obvious, Ronnberg 1990. Limiting factor A high level of nitrogen or phosphorus is not eutrophicating in itself. Both elements have to be present in balanced proportions. For optimal algal growth, the nitrogen content should be 7 - 10 times the phosphorus content, by weight. Most scientists, in the Baltic area, agree that for the whole area, except for the Bothnian Bay, nitrogen is the most limiting growth factor. However, one scientist, Soderstrom (1988) has the opinion that phosphorus is the most limiting compound. [] TL: Nutrient conditions, eutrophication and its effects in the Baltic Sea (GP) SO: Report prepared for Greenpeace International DT: August 1990 Keywords: oceans baltic sea greenpeace gp reports / [part 2 of 5] Contents Abstract 2 Nutrient conditions in the Baltic Sea area 3 Definition 3 Unique conditions 3 Nutrient conditions 3 Nutrient sources 4 Limiting factors 5 Effects 6 Effects on phytoplankton 7 Effects on macroalgae in the coastal zone 7 Effects on oxygen content 9 Counteraction 10 Is a 50 % reduction enough? 11 Annex 1 Water protection measures in Estonia 14 Water protection measures in Latvia and Lithuania 14 Excerpts from the Danish Water Protection Programme, dated Jan. and April 1987 15 Excerpts from the Finnish Water Protection Programme to 1995 16 Excerpts from Water Protection Plan for the Federal Republic of Germany 18 Annex 2 The Baltic Marine Biologists: Statement about drastic changes in the Arcona Sea 1989 20 References 21 Figures 25 NUTRIENT CONDITIONS, EUTROPHICATION AND ITS EFFECTS IN THE BALTIC SEA ABSTRACT The Baltic Sea area, as defined by the statutes of the Helsinki convention is severely affected by eutrophication (increased levels of the nutrient salts, nitrogen and phosphorus). The level of phosphorus in the surface water in the central Baltic Proper has increased by a factor 8, and for nitrogen by a factor 4 in twenty five years. For the Kattegat area, the increase may be even larger. A reduction of at least 50 % or even up to 70-80 % have been proposed by some experts. When estimating the nutrient balance of the Baltic Sea area the balance between high fish production and fish catch must be considered. The biological effects are manifested in an increased production of organic matter by phytoplankton (plankton blooms, algal blooms) and macroalgae. The sedimentation of organic matter to the bottom has resulted in reduced oxygen level or completely anoxic conditions in the bottom water. Anoxic conditions are now found at approx. 1 00 000 km2, or 30% of the bottom surface in the Baltic Sea area. Vast areas of anoxic bottoms, bottoms with with very low oxygen content, are now frequently found in the south part of Kaftegat, in the north part of (bresund and in the Kiel Bight adjacent Danish coastal waters. This is now a serious threat to the whole Baltic marine environment and to the important cod fishery, as the reproduction areas are destroyed. The only counter action is a rapid reduction of nitrogen and phosphorus in the whole area. The decisions, by the Baltic countries, to reduce the nutrient outflow by 50 % to 1995, may not be enough, and can hardly be implemented. The nutrient load is, to a large extent, of antropogenic origin. NUTRIENT CONDITIONS IN THE BALTIC SEA Definition According to the definition the Baltic area consists of the following areas: The Bothnian Bay, Bothnian Sea, Aland Sea, the Gulf of Finland, the Baltic Proper, the Belt Sea including the Oresund (the Sound) and Kattegat to the line Gothenburg -Skagen (map 1). Unique conditions The area, which is the largest brackish area in the world, is characterized by a unique salinity gradient, from the Kaftegat to the Bothnian Bay. The surface water salinity has its maximum in the northern part of the Kattegat, with about 25 - 30 o/oo (parts per thousand), and is then slowly decreasing to about 2 o/oo in the northern most part of the Bothnian Bay. Along the coast of Kattegat, and especially in the Belt area, the salinity gradient is very unstable and characterized by a large daily, seasonal and long term variation. Beside the salinity gradient there exists a marked stratification in salinity, with lower salinity in the surface water, and a higher salinity in the bottom water. The halocline in the Belt Sea and Kaftegat area is normally to be found at about 10 - 15 m in depths, and in the Baltic Proper normally at 80 - 100 m in depths. One factor, which is very important for creating these phenomena, are the thresholds in the Belt area. In (Dresund, between Malmb and Copenhagen, the sill depth is not more than 8 m, and in the Great Belt the sill depth is about 17 m. The salinity situation is affecting both the organisms in the area, as well as the bottom conditions in the Kattegat, the Belt area and in the Baltic Proper. The salinity has a very strong influence on the species distribution along the gradient. The number of species are very much decreased. In the Bothnian Bay only a few percent of all the marine species can survive. Beside the number of species, their size is reduced, their vertical distribution is changed, the reproduction is disturbed and the metabolism rate is changed, etc. Nutrient conditions The whole area is affected by elevated levels of nutrient salts, e.g. nitrogen and phosphorus, 'eutrophication". During the last 25 years the nitrate nitrogen, in the surface water of central parts of the Baltic Proper, on average, has increased from 1 to 4 lumov), thus a factor four (4), and the phosphate phosphorus from 0.1 to 0.7 /umol/l, Nehring 1984, fig. 1. The concentration of nutrients have increased in almost all parts of the Baltic, with the exception of the Bothnian Bay, Wulff & Rahm (1 988). The corresponding increase in the Belt area and in the Kaftegat is 6 resp. 1 0 times, Anon (1 988). From Nehfing (1 988) a slight decrease in the nitrogen- and phosphorus values in the central Baltic can be found. Whether this is due to a real reduction of the input, or just some inter-annual variation due to other factors, is too early to say, fig. 2. Nutrient sources The main sources for the increased nutrient content are domestic and industrial sewage, land run-off, atmospheric downfall, nitrogen fixation and fish farming. According to Larsson et al (1 985) the total annual amount of nitrogen and phosphorus brought into the entire Baltic is about 1 million tons resp. 70 000 tons, tab. 1. Wulff & Rahm (1 988) have revised these figures, and got about the same results; a difference of about 1 0 % was found. Tab. 1 Total input of nitrogen and phosphorus and BOD (Biological Oxygen Demand) in tons/year. Larsson et al 1985. BOD TOT-P TOT-N 5/7 Bothnian Bay 179.300 3.400 60.100 Bothnian Sea 231.400 3.800 85.000 Gulf of Finland 330.100 5.000 75.000 Baltic Proper Municipal 109.600 12.0000 54.900 Industrial 80.800 600 5.700 Rivers 592.400 40.800 466.600 Atmosphere - 9.000 260.000 N2-fixation - - 130.000 Total 782.800 62.400 917.200 Oresund and Baltic Sea 174.400 7.700 65.800 Baltic Sea total 1.698.000 82.300 1.203.600 The urban and industrial waste water contribute only to about 20 % of the total phosphorus input and 6 % of the total nitrogen input. The major sources are land run-off and atmospheric downfall. The latter consists of both dry and wet deposition. A recent estimation by Iversen et al (1 989) found the total deposition to the Baltic Sea, in 1988, to be 315 000 tons. This originates from about 20 different countries. One also has to bear in mind that the nitrogen from atmospheric downfall over the land surface, to a larger or smaller extent, sooner or later is transported from the soil to rivulets and rivers, to lakes and to the sea. As the drainage area of the Baltic Sea is at least three times bigger than the Baltic Sea, even a small leakage/ha will end up with a substantial contribution to the eutrophication. The downfall of nitrogen has been estimated to approx. 60 kg N/ha and year in the Netherlands, in Denmark and the south part of Sweden to 30-40 kg, and in the north part of Sweden and Finland to about 8-1 0 kg/ha and year. The agriculture in all the Baltic countries are also contributing to the excess of nutrients by land run-off, both in form of high doses of fertilizers and from extensive animal farming. Nitrogen fixation in the sea is made by blue-green algae. In the Baltic Proper and partly in the Belt area, it is mostly done by Nodularia spumigena. In condition with low nitrogen content in the water, and some surplus of phosphorus, the algae starts to take up atmospheric nitrogen and include it in the cell material. The nitrogen fixation takes place in the warmest part of the summer, in July, August and sometimes the first week of September. During optimal conditions the uptake rate can be several mg nitrogen/m2 and hour. When the algae are decaying, ammonium nitrogen is released to the water, and can be utilized by other algae. The fish farming in the Baltic Sea is still of little importance. Probably a maximum of 10 - 15 000 tons are produced annually. The phosphorus contribution is maybe 150 tons/year and for nitrogen about 1 000 tons. For the whole area the effects are negligible, though in some local areas, especially in the Aland area, the effects are quite obvious, Ronnberg 1990. Limiting factor A high level of nitrogen or phosphorus is not eutrophicating in itself. Both elements have to be present in balanced proportions. For optimal algal growth, the nitrogen content should be 7 - 1 0 times the phosphorus content, by weight. Most scientists, in the Baltic area, agree that for the whole area, except for the Bothnian Bay, nitrogen is the most limiting growth factor. However, one scientist, Sbderstr6m (1 988) has the opinion that phosphorus is the most limiting compound. 5 [] TL: Nutrient conditions, eutrophication and its effects in the Baltic Sea (GP) SO: Report prepared for Greenpeace International DT: August 1990 Keywords: oceans baltic sea greenpeace gp reports / [part 3 of 5] Effects Increased levels of nutrient salts may increase the growth of plants. in the Oresund and Great Belt area it was concluded already in the middle of the 70-ties, that the primary production of phytoplankton had increased. For Oresund Edler (1977) estimated the increase to three times the values in the 50-ties, which showed a good agreement with Steeman Nielsen (1933) values from 1931. For the Great Belt area the primary production was more or less doubled, Gargas et al (1 978) and Aertebjerg et al (1984). For the Baltic Proper the time series are not long enough to allow precise statement. There are indications that, since the beginning of the 60-ties, the production values have been doubled, Schulz (1985). Older data for phytoplankton production is veryscarce. Fonselius (1972) calculated the production to be 26 x 10(6) ton Carbon/year. Hallefors & Niemi (1981) gave the number 30 x 10(6) ton Carbon/year. Schulz (1985) reported 47 x 10(6) ton Carbon/year, and gave the following basic data for dfferent subareas of the Baltic area. tab. 2. Tab. 2 Area x Primary production Total production (Surface area km2) g C.m2.a1 t.10(6)C.a1 The Belt area 19.109 165 3.15 The Sound 1.243 165 0.21 Arkona Sea 18.673 154 2.88 Bornholm Sea 38.990 129 5.03 Gulf of Gdansk 25.600 129 3.30 Gotland Sea 125.950 129 16.25 Gulf of Finland 29 571 140 4.14 Bothnian Bay 36.804 25 0.92 Bothnian Sea 64.537 110 7.10 Aland Sea 5.496 110 0.60 Archipelago area 9 042 140 1.27 Riga Bay 18.096 140 2.53 Total 393 111 km2 47,38 (Schulz 1985) 6 Schulz (1985) gives an account for the trend in primary production and biomass (chlorophyll a ) from 1975 - 1983. For the biomass he found an increasing trend for both coastal and open sea areas. In the Gotland Sea the biomass increased with ca 47 % from 1975 - 1978 to 1979 - 1983. The corresponding value for coastal water (Arkona Sea) was 56 %. The increase in primary production for the same areas were 6 % and in coastal water 41 %. Effects on phytoplankton The elevated nutrient level has thus increased the primary production and biomass in the Baltic region. This could also be seen as an increased mass occurrence of phytoplankton (plankton blooms/algal blooms) of several species. In the Baltic Proper especially the increased frequency and duration of the blue-green algal blooms must be pointed out. In the Kattegat area the frequency and magnitude of dinoflagellate blooms has increased during the 1980s (Graneli, 1986). These algae can sometimes be poisonous which have affected, for instance, the mussel cultivations. The heavy bloom of the strongly poisonous Chrysochromulina polylepis in the Kattegat and Belt area in 1988 is another example of this phenomenon (Lindahl and Rosenberg, 1989). Changes in the species'composition of the phytoplankton flora have been recorded in parts of the Baltic Proper and in the Kattegat area. The increased phytoplankton production and the following increase in biomass is one of the most important factors for the drastic changes in the oxygen conditions in the whole Baltic area. Effects on macroalgae in the coastal zone Concerning the larger seaweeds and macroalgae, there are very few, if any, measurements that can prove an increase in production or biomass. On the other hand, many investigations show that changes in species composition have taken place during the last 25 years. The macroalgal flora has changed from more slow growing perennial species, like Fucus vesiculosus (bladder wrack) and Fucus serratus, to more fast growing annual species of green , brown and red algae. This is shown from the Danish waters by Mathiesen (1990), for West Germany areas by Schramm et a] (I988), along the East German coast by von Oertzen et al (1989), in Poland by Plinsky (1986), in Estonia by Trei (1985) and for Finland by Ronnberg et al (1985), the Oresund area by Wachenfeldt (1975). Judging from theoretical calculations, with the use of Mitcherlisch-Boules equation it is obvious that the macroalgal biomass has more of less been doubled during the last 25-30 years. This is also in good agreement with more subjective fieldassessments. The decrease of the Fucus- and Characommunities are summarized by von Wachenfeldt et al (1986). In Kiel Bight only 20 % of the Fucus biomass remains in comparison with measurements 20 years ago, Schramm et al (1988). The increased biomass of macroalgae is creating problems in many ways. Some parts are sedimenting to the bottom, and are transported to deeper parts of the Baltic. Some parts of the biomass are trapped in fishing nets and trawls, and thus creating problems for the fisheries. Sometimes very large amounts are washed ashore and cause nuisance by smelling etc. In some areas of the Baltic, the sandy beaches, due to fertilization, are transformed to grassland covered with high growing grass- species. The increased biomass also has a capability to bioaccumulate nitrogen and phosphorus, as well as trace elements and chlorinated hydrocarbons. The increased level in the seaweed is also a good indicator of the increasing load in the water fig. 3 and tab. 3. Tab. 3 Content of nitrogen and phosphorus in mg/g dry weight in FUCUS VESICULOSUS from different times from the southern coast of Sweden. @ Weibull 1919 ** Kornfeldt 1982 Min N/X Max Min P/X Max N/P Oresund 1900-1930 5,0 14,3 20,7 0,3 0,9 1,3 15,9 Oresund* 1919 14,0 1,0 14,0 Kullen 1972-1974 9,4 23,3 35,8 0,4 2,0 5,2 11,7 Kullen** 1979-1980 20,0 23,1 35,0 1,1 2,1 3,0 11,0 Halland 1984-1985 24,0 26,5 32,0 3,5 5,5 7,0 4,8 Blekinge 1973 11,6 13,5 15,4 1,1 1,4 1,9 9,6 Blekinge 1981 20,5 22,3 31,3 1,8 2,3 3,3 9,7 Blekinge 1982 20,3 24,4 31,5 2,1 2,3 2,6 10,6 Blekinge 1987 21,9 24,1 31,6 2,1 2,8 3,7 8,6 In the south part of Kattegat the phosphorus level in the Fucus tissues has increased 6 times during the last 50 years, for nitrogen the increase is 4 times, von Wachenfeldt & Waidemarsson (1988). The same tendency is also documented from the Kiel Bight area by Schramm (1988). The decrease in Fucus plants and the increase of filamentous algae has also another serious effect in the Baltic Proper. The Baltic herring, when spawning, are normally attaching their eggs to the Fucus plants. When these disappear, the herring has to attach the eggs to other seaweeds, with very negative results, Persson et al 1989. Aneer (1987 and 1990) has convincingly shown that some of the filamentous algae, which have increased their biomass, produce some compounds which strongly reduce the number of living eggs. The increased production of organic matters has lead to large scale changes in the pelagic communities. Although very few convincing investigations have been made, the benthic fauna, above the halocline in the Baltic Proper, have increased 3-5 times during the last 50 years, Cederwall & Elmgren (1980). Effects on oxygen content The most dramatic changes have taken place below the halocline. The increased sedimentation of organic matter have resulted in vast areas of bottom water, with low or non oxygen content, which have resulted in formation of hydrogen sulphide (H2S), which is a strong poison, fig. 4. The Swedish scientist Fonselius, already in 1969, wrote "if this development continues in the Baltic deep water, the whole water mass below the halocline will soon turn into a lifeless "oceanic desert" such as is found in the Black Sea. The present stagnation will probably lead to a catastrophe for the bottom fauna in the deep areas of the whole Baltic Proper." The first sign of H2S was found in the Gotland deep in 1960, since then it has increased in area and volume, which can be seen in fig. 5, Andersin et al (1988). Today about 100 000 km2 bottom surface in the Baltic Proper have, more of less, permanent anoxic conditions. In these areas the fauna, of course, is completely wiped out, fig. 6. This is about 30 % of the bottom area. This has decreased the feeding areas for cod, and is now also affecting the reproduction of the cod in a negative direction, This is one of the grounds for the decreasing catches of fish in the Baltic Proper, Sjostrand (1989). In the north part of Oresund and the south part of the Kattegat anoxic conditions have been frequent during parts of the years since 1977, even in shallow water areas from 15-20 m in depths. This has created large problems for the fishermen in the area. The catches of for instance cod, have gone down with 50 %, Pihl (1988). 9 As can be seen in fig. 7 there has been no inflow of oxygen rich water to the deeper parts of the Baltic Proper since 1976, Matthaus (1986). The salinity of the bottom water below the halocline, has slowly decreased and it is possible to expect an inflow of oxygen-rich water during the coming years, Nehring (1989) The question is then, what will happen to the nutrients, which have been stored in the bottom water and sediment? The increasing anoxic conditions in the deepwater has been regarded as a sign of eutrophication by many scientists, for instance, Jansson 1978. Fonselius (1969), on the other hand, was of the opinion that natural hydrographical changes could have caused the present condition. This may be possible as there are indications of anoxic conditions during earlier centuries, Hallberg (1974). Calculation by Schaffer (1979) showed however that the present conditions is a result of an increased organic load due to eutrophication. Rosenberg et al. (1990) is of the same opinion. Counteraction Within the Helsinki Commission an unanimous decision was taken: Declaration on the protection of the marine environment of the Baltic Sea area - adopted on 15 February 1988 in Helsinki by the ministers responsible for the environmental protection in the Baltic Sea States with the following statement: "Do hereby declare their firm determination to make further provisions for reducing discharges from point source, such as industrial installations and urban wastewater treatment plants, of toxic or persistent substances, nutrients, heavy metals and hydrocarbons by construction and operation of installations and equipment in conformity with the best available technology. In this context it is noted that actions concerning nonpoint sources will also be needed. In order to fulfil these objectives current and new efforts on reduction of the load of pollutants should aim at a substantive reduction of the substances mot harmful to the ecosystem of the Baltic Sea, especially ofheavy metals and toxic or persistent organic substances, and - nutrients, for example in the order of 50 per cent of the total discharges of each of them, as soon as possible but not later than 1995". In accordance with this decision all the Baltic countries have adapted national programmes about eutrophication. (Some of these are presented in abstract form Annex 1). Besides this also the Paris Convention/Commission has taken a decision to reduce the nitrogen and phosphorus outlet from urban sewage treatment plants. 10 Is a 50 % reduction enough? This question is very difficult to answer, due to the differences in volume, salinity, current conditions (for instance the inflow of deeper water from Skagerrak, with relatively high nitrogen content) in the different parts of the Baltic Sea area. If one agrees that the total annual load to the Baltic Sea area is 82 000 tons of phosphorus and 1 203 600 tons of nitrogen, a 50% reduction means about 40 000 resp. 600 000 tons per year. The most easy way to act is to increase the efforts in the treatment plants. For the whole Baltic area this would yield maximum 10 000 resp. 100 000 tons, which is only 25% of the goal for phosphorus and 15% of the nitrogen goal. To get a substantial cut down of the load, the land run-off and the atmospheric downfall must be drastically reduced. If both these sources are cut down by 50% it means a reduction with altogether 25 000 tons of phosphorus and 355 000 tons of nitrogen. Together with the enhanced sewage treatment, the sum will be approx. 35 000 tons of phosphorus and 455 000 tons of nitrogen. This is about 90% of the wanted phosphorus reduction and 75% of assumed nitrogen reduction. In a larger perspective the nitrogen fixation, as a result of the other actions mentioned above, will be slowly reduced. It is possible that a 50% reduction of the inflow of nitrogen to the Baltic Proper, would reduce the concentration of nitrogen, in the surface water, during wintertime (this means a reduction from 4.6 - 2.3 /umol/1), as there is very little input from the water below the halocline. This would also affect the conditions in the Belt Sea and the south part of Kaftegat. Fleischer et al (1989) have estimated the reduction to 1.2 /umol/l, tab. 4. Tab 4. Concentration of dissolved inorganic nitrogen in /uM, in the surface water at different parts of the Baltic Sea area, before the spring-bloom during 1982-1985 (salinity in brackets) at different reduction levels for the different areas. The difference between the lines 1 and 2 is equal to line 3, which gives the importance of the local nitrogen contribution. Changes like a 50% reduction of the dissolved inorganic nitrogen in different areas show, line 4 to 6, which levels can be achieved, Fleischer et al 1988. Tab. 4 Skaggerak Baltic P Kattegat SEKattegat Laholm measured conc. 9.8 (33) 4.1 (8) 8.2 (18) 7.9 (22) 10.6 (17) without local sources 9.8 4.1 7.3 6.4 6.1 local sources - - 0.6 1.8 4.5 50% reduct. in the 9.8 2.3 7.1 7.1 9.4 Baltic Proper 50% reduct. in the 9.8 4.1 7.8 7.8 8.9 Laholm Bay only 50% reduct. in the 9.8 2.3 6.8 6.0 7.0 Baltic, Oresund, Sklilderviken and Laholm Bay In the Bothnian Bay, which still is considered to be oligotrophic, the effect probably will be rather small, Wulff & Rahm 1988. On the other hand, in the Gulf of Finland, with very high nitrogen content, and a comparatively small volume, the effect should be noticeable. The improved conditions in this area will, of course, also have some effect on the conditions in the Baltic Proper. If one reduce the nitrogen level in the Baltic Proper with 50%, from 4.5 to 2.2 /umol/I in the surface water, during wintertime, this will mean the same conditions as the beginning of the 1970-ties. The same is valid for the phosphorus situation. Even at that time the signs of eutrophication were quite evident. Judging from Schulz (1985) the primary production at the beginning of the 1970-ties was in the order of 120-130 g Carbon/m2 and year, with a corresponding biomass of about 35 mg Chl a/m2. Probably the primary production should be reduced to about 80-100 g C/m2 and year to get a substantial reduction of the organic load. 12 [] TL: Nutrient conditions, eutrophication and its effects in the Baltic Sea (GP) SO: Report prepared for Greenpeace International DT: August 1990 Keywords: oceans baltic sea greenpeace gp reports / [part 4 of 5] As nitrogen is believed to be the most limiting nutrient in the Baltic Sea area except for the Bothnian Bay and the Bothnian Sea, the most important goal is to reduce the nitrogen load. One important factor that must be discussed and taken into consideration is the denitrification, which is a bacterial process which converts nitrate to nitrogen gas at anoxic/near anoxic conditions. This process in the Baltic has been discussed in detail by Ronner 1985. He comes to the conclusion that the denitrification prevents excessive eutrophication by removing nitrogen from the system. According to his budget calculations a total loss of nitrogen through denitrification should be in the order of about 500 000 tons of nitrogen per year. It is however uncertain if the capacity is large enough to remove an increased flow of nitrogen in the Baltic. According to Larsson et al (1985) at least 15 000 tons of phosphorus or more, may be lost from the system by accumulation in the sediment in the oxygenated parts of the Baltic. Larsson et al (1985) have also made an attempt to estimate the input before the 20th century when the antropogenic influence was very small, and came to the result, that the annual addition was about 9 600 tons of phosphorus and approx 300 000 tons of nitrogen. This is about 15% for phosphorus and 25% for nitrogen of the values today. Ackefors and Lindahl (1979) estimated the primary production in the Baltic proper to be 169 g C per m2 and year. This production needs about 520 000 tons of nitrogen, Ronner 1985. A primary production of 80-100 g C per year could be considered to be more natural to the Baltic Proper. This would require about 260-300 000 tons of nitrogen. These figures are in good agreement with the estimation of Larsson et al for the historical value of about 300 000 tons of nitrogen per year. It is of great importance that the primary production is high enough to maintain a high fishproduction. Thus it can be concluded that a 50% reduction of the nitrogen out- flow to the Baltic Sea area is a minimum goal and it may not be substantial enough to improve the condition in the Baltic. Judging from reports from the different Baltic countries it is not likely that this goal can be achieved by 1995, compare Annex 1, Finnish Water Protection Programme to 1995.. In Sweden at least some of the larger sewage treatment plants with the Baltic sea area as a recipient will have their nitrogen reduction of 50% in 1992 and to 75% in 1995 in use in time. In many of the other countries this will not be the case. None of the countries will be able to reach the goal to reduce the land run off to 50% of the present values to 1995. 13 ANNEX 1. Water Protection measures In Estonia On Dec 6, 1988 the Supreme Soviet and the Estonian SSR (the Parliament) passed a resolution "Concerning the aims and the situation of nature protection and the utilization of natural resources in the Estonian SSR". Along with this resolution "Conception of nature protection and rational utilization of natural resources in the Estonian SSR" was passed. Its article c. 6. proposes the lessening of conducting into water bodies waste substances especially dangerous to the ecosystem (heavy metals, nutments, toxic compounds, etc.) by the year 1995, by at least 50%. This resolution corresponds totally to the Ministerial Declaration signed at the 9th meeting of the Baltic Marine Environment Protection Commission. In 1989-1995 in 32 Estonian towns and settlements new biological sewage treatment plants must be constructed or existing ones enlarged. All biological purification plants for whole towns are intended to include phosphorus removal. Also the application of nitrogen removal is planned. The greatest obstacle in constructing purification plants, is the lack or shortage and inferior quality of the necessary equipment. Besides towns and settlements also needs of industrial and agricultural purification systems must be taken into account. Water Protection measures In Latvia and Lithuania The new biological purification plants of Riga is planned to be in operation before 1995. The first step (ca 50% of the total capacity) should be in operation before 1991. The biggest pollutant of the Riga Bay, the Sloka sulphate pulp mill, should be closed. That means that the beaches in Jurmala can be reopened. A biological purification plant should be constructed in Liepaja. In Lithuania the main problem is to restore the water quality in the Kura Bay and in the river Neman. In Kaunas a biological-chemical sewage purification plant (ca 420-th-m3/d) should be constructed. The Klaipeda sulphate pulp mill should be reconstructed using advanced environmentally sound technology. Also the biological purification plant in Vilnius should be finalized. Removal of phosphorus compounds should be done in all towns and settlements. In the future also removal of nitrogen compounds must be examined. 14 EXCERPTS from the Danish Water Protection Programme, dated Jan. and April 1987 This programme contains among others the following points: - To reduce the outlets of nitrogen with 50%, and for phosphorus with 80% before 1994. - About 270 larger sewage treatment plants will reduce the phosphorus content with 90% to ca 1.5 mg/l. This means a total reduction from 7 500 tons to 2 000 tons/year. - About 1 1 0 sewage treatment plants will reduce the nitrogen content to maximum 8 mg/l. This means a total reduction from 25 000 tons to 1 0 000 tons/year. - From agriculture the leakage shall be reduced from ca 4 400 tons of phosphorus/year to approx. 400 tons, and for nitrogen from 270 000 tons to 143 000 tons/year. - Compulsory storing capacity for manure for 9 months production, including coverage for manure tanks. - Planning of land use and special planning for fertilizing, will reduce the consumption of fertilizers to 50% of todays values, which is equal to a reduction of approx. 190 000 tons of nitrogen/year. If this goal is not achieved, there will be a special tax on fertilizers. - Compulsory crops in autumn and winter on 45% of the acreage in 1988, and 65% in 1990. - No spreading on bare land from harvest to the 1st of November. - Spreading of liquid manure on bare land must be covered within 12 hours. 15 EXCERPTS from the Finnish Water Protection Programme to 1995 - On 6 October 1988, the Finnish Council of State issued a decision-in- principle on a programme of objectives for water protection to be achieved by 1995. This document represents its political stance on water protection and is a means of setting out both the objectives of the promotion and direction of water protection in Finland, and the practical approach to it. - The main purpose of the decision-in-principle as a programme for water protection is to improve the state of Finnish waters and ensure their continuing usability. The document states that the most effective economically feasible measures must be adopted for water protection, and these will be selected, as far as possible, on the basis of assessments of need and of the overall targets set for load reduction, on a case-by-case basis. - Among the major problems affecting Finnish watercourses are: oxygen deficiency caused by the discharge of effluent, eutrophication, the effects of toxic substances on organisms, and acidification of waters. Almost 90 per cent of the oxygen demand loading in waste water in Finland originates from the pulp and paper industry. The main cause of eutrophication is phosphorus loading, although in some areas it is caused by nitrogen loading. The major sources of phosphorus loading are agriculture, the pulp and paper industry and the activities of the communities. The main sources of toxic substances are industrial effluent, agricultural pesticides, refuse dumps, and deposition from the air, which also causes nitrogen loading of the lakes. In many areas, the natural environment and the watercourses themselves have been radically altered by water-regulation and control of flow in watercourses and by other construction in surface waters. - The decision-in-principle will result in a considerable reduction in water loads, producing a fundamental improvement in the condition of Finnish waters. The oxygen demand loading from the pulp and paper industry will fall by about 65 per cent and phosphorus loading by about 25 per cent below their 1986 levels. At the same time, the amount of organic chlorine compounds entering watercourses will be considerably reduced. Oxygen demand loading originating from communities will fall by about 30 per cent, and phosphorus loading from this source by about 15 per cent below 1986 levels. Phosphorus loading from agriculture will fall to about half the present level of 1800 tonnes per year. - The implementation of the decision-in-principle will result in an overall reduction by 1995 of oxygen demand loading of waters from various sources to less than half the 1986 level, accompanied by a reduction of almost 40 per cent in phosphorus loading. Other substances which are harmful to the aquatic environment will also be significantly reduced. Although the objectives spring from Finland's need to reduce loading of its own watercourses and coastal waters, the loading of the Baltic Sea and its Gulfs will also be reduced by an amount sufficient to satisfy Finland's international commitments. 16 - Waste water treatment will be considerably intensified both in those industrial plants which are connected to the public sewer systems and in small industrial plants which have their own discharge sewers, In the treatment of municipal waste water, steps will be taken to ensure that, on average, the results are those of an effective biochemical treatment method. This means, from the point of view of total loading, purification efficiency of at least 90% in the removal of organic matter and phosphorus. Elimination of 95% of phosphorus, i.e., a residual concentration of 0.3 - 0.5 mg P/l, will be required when the receiving body of water is of particular significance from the point of view of use or conservation. - If the ammonium in the waste water has a harmful effect on the oxygen balance of a watercourse, on the stock of fish or on the water withdrawals, it will be required that the waste water shall be nitrificated, i.e. the ammonium shall be oxidized into nitrate. A feasibility study will be made into more effective methods of eliminating the nitrogen content of municipal waste water, particularly in treatment plants which give rise to a nitrogen loading that produces a marked increase in eutrophication. Any necessary measures for this will be put into effect. - Requirements for loading reductions of water will be imposed on agriculture similar to those imposed on other activities which give rise to loading of marine and inland waters. In order to reduce the loading from agriculture, water protection measures will be developed and introduced both in animal husbandry and in arable farming. At the same time efforts will be made to ensure that financial support will be available from the government to accelerate activities aimed at reducing loading. - The storage, handling and spreading of manure and silage liquor from old cattlesheds will be brought largely to the same standard as is currently required of new farms, except in cases where it is planned to cease animal husbandry by the year 1995. This will markedly reduce direct discharges from animal husbandry. At the same time the oxygen demand loading of watercourses will decrease significantly and the sanitary quality of waters will improve. 17 Excerpts from Water Protection plan for the Federal Republic of Germany IV. Additional activities by Schleswig-Holstein for the Implementation of the resolutions/recommendations of the Ninth Meeting of the Helsinki Commission All measures mentioned in sections I - Ill also apply to the State of Schleswig-Holstein - the most northerly region of the Federal Republic of Germany with coasts bordering the North and Baltic Seas - which is solely responsible for the input of pollutants into the Baltic Sea. None of the other regions of the Federal Republic are involved. In order to comply with requirements laid down by the London and Helsinki conferences, Schleswig-Holstein has taken independent steps to achieve a drastic reduction in the input of nutrients and pollutants into the North and Baltic Seas. These measures are entirely independent of the legal regulations already enforced or planned for the field of water protection. Within the framework of a special programme taking immediate effect, all of the larger waste water treatment plants in Schleswig-Holstein handling more than 1 million cubic metres of waste water per year (38 of 80 plants) have been equipped with chemical precipitation facilities for the reduction of phosphate input. This required additional construction work in the case of 20 waste water treatment plants - 18 were already equipped with chemical precipitation facilities in 1988. In January 1990, 35 waste water treatment plants were equipped with chemical precipitation facilities and operative. The last three waste water treatment plants will become operative by June 1990 at the latest. Concentrations of phosphate in the effluents of their waste water treatment plants may not exceed 2 mg/l. In fact, the annual mean value is less than 1.5 mg/l. Further measures are planned to be taken, through which a control value of 0,5 mg/l is sought to be complied with by 1995. As a result of all of these measures combined, 67% of the population of Schleswig-Holstein is served by phosphate elimination facilities and 80% of the collected polluted water is treated by this technology. This will lead to a reduction in the input of phosphates into the Baltic Sea by approx. 50%. In parallel to this, a further extension measures for treatment plants is being taken within the context of a priority programme, which will lead to the maximum possible elimination of nitrogen by means of nitrification and denitrification. In addition to this, it is planned to install a filter system in the waste water treatment plants and to improve chemical phosphate precipitation by constructing a biological phosphate elimination installation. This wilI reduce the input of precipitation agents and the occurrence of sludge. As a result, the elimination of phosphorus will also be increased to 98 % in the individual plants. Under this process, all pollutants which are still bonded to suspended particulate matter in the waste water will also be eliminated. These highly ambitious goals can only be achieved through the use of the best available technology. 18 Schleswig-Holstein is therefore working in close cooperation with institutes of the Universities of Hannover and Hamburg which are highly specialized and experienced in this field. The entire extension measures are to be completed by 1995. Costs will amount to approximately DM 450 million. This will allow the development of a waste treatment system which will more than satisfy the requirements of HELCOM-Recommendations 9/2. Schleswig-Holstein is currently drafting a regulation to reduce the application of nutrients within the agricultural sector. This regulation will restrict the periods when manure can be applied, and, with respect to existing areas used for agricultural purposes, will also limit the quantities used. The application of manure within five metres of water boundaries will also be generally prohibited. Large agricultural areas will be set aside in order to prevent the over-production of agricultural products. The selection of areas will be based on the criterion of water protection. In addition, within the context of a special programme, strips of land of 1 0 to 20 metres alongside specific water bodies are to be excluded from any kind of fertilization or the use of plant protection agents. Special compensation will be awarded to farmers. Preliminary investigations estimate that the input of phosphates and nitrates may be reduced by as much as 80 % by natural vegetation which will as a result occur. In addition, Schleswig-Holstein is also promoting the development of new technologies for the treatment and application of manure in order to prevent leaching into the groundwater and surface water in the future. In the catchment area of the Baltic Sea in the Land of Schleswig-Holstein, only a few industrial plants are equipped with discharge outlets with direct access to waters. Talks are currently being held with these firms in order to optimize waste water treatment in this area, too, and to ensure that the best available technology is introduced as quickly as possible, even if not yet required by law or stipulated for a later date. It is expected that the firms will improve their water treatment systems on a voluntary basis if the technology is available. It can generally be assumed that, through the further expansion of waste water treatment systems in cities and smaller communities and in the industrial sector as well as supplementary measures in the agricultural sector, the input of pollutants and nutrients into the Baltic Sea by the Federal Republic of Germany will be significantly reduced by 1995 and that the recommendations of the Helsinki Commission will thus be fully complied with. 19 [] TL: Nutrient conditions, eutrophication and its effects in the Baltic Sea (GP) SO: Report prepared for Greenpeace International DT: August 1990 Keywords: oceans baltic sea greenpeace gp reports / [part 5 of 5] ANNEX 2 The Baltic Marine Biologists (BMB) Statement about drastic changes in the Arcona Sea 1989 The Baltic Marine Biologists express their deep concern about recent changes in the Arkona Basin reported by Dr Heye Rumohr, Inst. f. Meereskunde, Kiel to the BMB Symposium held in Szczezcin this year. During a Monitoring cruise with RV "Littorina" in June 1989 TV-recordings revealed wide-spread spots of sulfur bacteria (Beggiatoa) on the sea floor surface, together with dying macrofauna. Grab samples as well as dredge tows showed no living macrofauna at a station that in the preceeding years - although impoverished - was still vital (BYl). Additional sediment-profile photographs (REMOTS) showed a black organic layer on top of the normal muddy sediment covered by the above mentioned layer of sulfur bacteria. As seen from other Baltic Basins these findings indicate a severe change in the ecosystem. Before 1989 there was a rich mollusc-dominated bottom fauna community which served as good food for bottom living fish. Food items for fish are now very scarce on these bottoms. The severe consequences for the fish populations can only be speculated at this moment. The high organic load must be oxidized and will cause in short time oxygen deficiency in the bottom water, which in turn prevents new fauna from settling and starting a new recolonization. The actual reason for this drastic change in the Arkona Sea is still unknown, although it is quite obvious that a high organic input both from coastal primary production as well as from plankton blooms goes beyond the uptake and conversion capacity of the seafloor system. The present condition in the Arkona basin are certainly linked to the deterioration of the water quality in the southern Kattegat, the Belt Sea, Kieler and Mecklenburger Bucht. This process is nevertheless also governed by hydro-meteorological conditions. This complex will be investigated with priority at 1990 monitoring cruises. 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