1.Introduction
The Baltic Sea, located in North Europe, has a bit more than 100.000 km² and it receives discharges of a population around 70 million inhabitants with a high level of industrial development, because of 15% of world industry production is located in that area. Before 1960 their waters were so clean, but after that the sea has been changed and now it's one of the most polluted seas in the world.
There are some natural factors that contribute to that the Baltic Sea is one of the most polluted seas in the world; the Baltic is a inland sea, it has high population in 9 coastal states and 5 states partly inside the drainage basin. More than 200 rivers and streams discharge into the Baltic Sea. In Sweden there are more rivers than in the rest of the countries that are inside drainage basin. Another factor is the clearly stratification of the water; the water is salted but the sea receives big quantities of fresh water from the rivers that flow in it. Those two kinds of water don't mix enough and it forms two different layers: one in the deep with the salt and the other above that because it's less dense. Because of those two layers don't mix, the salt water doesn't have much oxygen and with any factor of pollution that decreases that oxygen's level has terrible consequences.
Also is a shallow sea, the islands of Denmark work as a dam which stop the shallow waters of the Baltic Sea before mixing with the ocean. Because of this the water of the Baltic Sea has a long residence time, almost 33 years.
The catchment areas are very important for an aquatic system due to the water conditions depended of these areas. The mountains
produce the water divide that is transported from high levels (mountain peaks) to low levels (lakes, oceans). During this transport from high to low levels, water infiltration occurs, which infiltrate solid contaminants and nutrients.
In the Baltic Sea catchment area are included some 9 coastal states and 5 states partly inside the drainage basin. The most important are Sweden, Finland, Estonia, Latvia, Lithuania, Russia, Poland, and Denmark like coastal states, and Norway, Russia, Belarus and Germany like states partly inside the drainage basin. In the south of the Baltic drainage basin there is more farmland and a higher density of population than in the north. Some of the most important rivers are: torne, kalix, lule, pite, skellefte, ume, angerman, indals, ljungan, dalälven (Sweden), oulujoki (Finland), narva (Estonia), neva (Russia), daugava (Latvia), nemunas (Lithuania), wisla (Poland)...Etc.
Another point is the biodiversity of this brackish water sea. There are few species as a food web and they are more important in the Baltic than in other ecosystems because Baltic Sea is quite sensitive to these changes. So, if one key-specie disappears, the ecosystem is not able to survive reasonably intact.
Figure1: Map of Baltic Sea
The main problems of pollution in that sea are:
-Oil spills. Every year there is an average of three accidents who pour around 225 tons of petrol (10%). The rest come from the land. For example, one of the most dangerous is the PAH and in the Baltic the proportion is three times bigger than in North Sea.
-Eutrophication. In that see there are more than 500.000 metric tons of nitrogen and around 50.000 tons of phosphorus every year that comes from deposition of fertilizer, residual waters, untreated water and air pollution. It causes the massive increase of green-blue seaweed that, when they die in the end of autumn, fall down to the seabed where they being decomposed and that decrease the oxygen level.
-Harmful substances. The accumulation of substances like PCBs in the animal tissue (seals) means that's the reason of their decrease. From 20 years ago, due to special agreements substances like PCB and other toxic metals are decreasing, but nowadays the level is 3 or 4 times more than North Sea levels. Also the Chernobyl accident multiplied per 5 the level of Cs137. It's decreasing, but today is between 5 and 10 times higher than North Sea.
2. Materials and Methods
Before to understand this article and the importance of the topic, we must know the situation of the Baltic Sea area in the past, how it has evolved until the present and how it will continue in the future. For this, we have to include some graphics and numerical data which represent the state of the area, and how is polluted. We can obtain several data from books and websites, one of those sources is HELCOM.
HELCOM is the principal body of "Convention on the Protection of the Marine Environment of the
Baltic Sea Area" known as the Helsinki Convention. They produce periodic studies of the state of this area to check the development of policies aimed at protecting the marine environment of the Baltic Sea area. HELCOM initiated joint monitoring programs in the decade of 1970 to provide reliable information on the state of the marine environment. Quantified data entry is a prerequisite to interpret and evaluate the state of the environment and related changes in the open sea and coastal waters.
We can find a good source of data in some interesting books related with the topic. All of them come from Swedish Environmental Protection Agency and there are good titles like Change beneath the surface
Use and misuse of the nature's resources.
Figure 2 and 3: Baltic sea Scorecard, WWF Baltic Ecoregion Programme 2008. Toxic emissions (Tables 1 and 2) Cadmium and mercury, two highly toxic heavy metals, have been a particular focus of a number of regulatory agreements and reduction efforts in the Baltic in the past two decades. Further commitments to address emissions of cadmium and mercury were agreed on in the Baltic Sea Action Plan (BSAP). A similar commitment was given for the reductions in dioxins and furans (Table 2), with a particular focus on emissions from small-scale combustion appliances. Two analyses are made for each of these groups of toxins - the first looks at change in emission levels between 1990 and 2005. The second assessment zooms in on the last few years to see what the current trend is.
-Led: Combustion for energy production as well as waste incineration is still an important source and a significant stream of lead also enters the environment with products such as different instruments and electronic equipment.
Figure4: Estimated proportion of contributions fromdifferent sectors to the total annua anthropogenic emissions of lead from HELCOM countries in 2004.
-Cadmium: Baltic Sea originates from industrial activity, waste water treatment plants, the use
and environmentally unsafe handling of NiCd batteries, as well as agricultural fertilizers.
The main contributing industrial activities in the Baltic Sea catchment area include e.g. electronics, metallurgic industry, and production of paints, lacquers and varnishes, chemical products and plastic (mainly PVC). Soils and rocks also naturally contain small amounts of cadmium of which some ends up in the Baltic Sea.
Figure5: Estimated proportion of contributions from differentsectors to the total annual anthropogenic emmissions of cadmium from HELCOM conuntries in 2004
-Mercury: The chlor-alkali industry is the main contributor to mercury air emission as regards the intentional use of mercury, Other industries still represent minor sources of mercury emission, mainly due to contamination of the materials being processed.
Another significant source of air emissions of mercury is cremation. A significant stream of mercury also enters the environment via products such as dental fillings (amalgam), batteries, biocides, pesticides and fertilizers as well as various laboratory and medical instruments and lightning equipment
Figure 6: Annual estimated anthropogenic emissions of mercury of HELCOM countries from different sectors in 2004
Figure7a: Data source: HELCOM, Baltic Sea Environmental Proceedings No. 70 The Third Baltic Sea Pollution Load Compilation
Figure7b: Data source: HELCOM, Baltic Sea Environmental Proceedings No. 70 The Third Baltic Sea Pollution Load Compilation
Figure8: Number of detected oil discharges in the Baltic Sea, 1988-2001. The percentage of double-hulled, double-bottomed and single-hulled oil tankers at the main oil terminals around the Baltic Sea, May/June 2001.
In the tables below we can see the amount of Nitrogen and Phosphorus that countries inputs to the Baltic Sea from 1994 to 2003. The inputs of Nitrogen and Phosphorus have decreased around 40% in ten years.
Figure9: Riverine and coastal inputs of Ntotal of 9 countries in 1994-2003 as totals, t/year.
Figure10: Riverine and coastal inputs of Ptotal of 9 countries in 1994-2003 as totals, t/year.
3. Results
The combination of several factors contributes to the environmental problem of Baltic areas. A large drainage basin in relation to sea area provokes high pollutant input in relation to water volume and a high nutrient concentration from the agriculture.
Eutrophication starts in the marine environment when amounts of nutrients cause increased production of plant biomass. That process elevates amounts of organic matter in the ecosystem. The consequence is the decrease of oxygen and the formation of toxic hydrogen in the deeper regions. This has created dead bottom areas, with no typical animals of sea-bottom. This area cover a third of the bottom area of the Baltic Sea. The amount of nutrients imputed to the Baltic Sea has increased around five times the 1940's level.
Agriculture is the most important human-related source of these nutrients in the Baltic Sea. Farmers use artificial fertilizers and manure in big amounts and the surplus arrive to the rivers and ends in the sea. Residual waters from urban and industrial sources are another sign of eutrophication in the sea.
Figure11: The vicious cycle of eutrophication.
Changes of land use, the loss of wetlands and the discharge of sewage from urban and industrial sources have aggravated this problem. The development of microscopic plants of plankton and filamentous green benthic algae, they die and decay and that case are one of the first signs of eutrophication in the sea. Some of the plankton reduction gives harmful blooms. These excessive blooms and associated problems cause reduction of water quality, oxygen deficiency and increased turbidity. That increased levels of nutrients finally cause extinction of rare species and habitats.
Figure12: Areas of oxygen concentration in the Baltic Sea.
Not only the high load of nutrient affect directly the Baltic, also harmful substances like organic pollutants and heavy metals have direct consequences in this ecosystem. Men have produced more than 100.000 new chemicals last century and many of them are more or less toxic. Some of these compounds have been manufactured for use as pesticides, primarily against insect pests. They include DDT, toxaphene, chlordane... all of which have been applied in large quantities to farmland, for example. In Sweden and most other industrial nations, these agents have long since been banned, but some of them are still in use in a number of more southerly countries. Toxic and persistent industrial chemicals never intended to be released into the natural environment may nevertheless end up there.
Figure 13: Where affect of toxic pollutants
In relation with the northerly location, the low water temperature limits the capacity of micro-organism to break down organic pollutants, including oil and toxic organic substances. In winter, ice and the lack of light can slow down decomposition.
To understand better why pollutants affect the ecosystem in this way, we have to look at the properties of organic pollutants and heavy metals.
The organic pollutants are very stable. A stable chemical can cause damage over a long period of time, and can spread over large areas. The organic pollutants also are persistent because are resistant to degradation and thus comparatively long-lived in the ecosystem. These properties are due to their chemical structure, it means that are formed by aromatic hydrocarbons. If such compounds are halogenated (i.e. if some or all of their hydrogen atoms are replaced by chlorine, bromine or other halogens), both their stability and their fat solubility are usually further increased. They are lipophilic (fat-soluble); due to this property the organic pollutants are accumulated in living tissues of organism. In the case of persistent organic compounds, solubility in fats tends to be the main factor that enables bioaccumulation to occur. Of course they are toxic, particularly genotoxic even at low concentrations. A substance´s potential to act as a toxic pollutant is further enhanced if it is also to bioaccumulate.
With the cold climate, toxic substances could entry easily on the organism, increasing bioaccumulation and biomagnification. Bioaccumulation is the accumulation over time of pollutants in living tissues of organisms. In the case of persistent organic compounds, solubility in fats tends to be the main factor that enables bioaccumulation to occur. In the fatty tissues of aquatic animals, fat soluble pollutants can build up
to concentrations thousands of times higher than in the surrounding water.
Figure14: Bioaccumulation and biomagnifications.
Biomagnification occur with the increase in the concentration of a substance in the food chain, it means that there is a bigger accumulation on the top of the food chain. The organic pollutants have several effects on predatory species like grey seals or sea eagles, as well as fishes. About grey seals, they have several problems in the reproduction because are produced uterine occlusions, it means that is avoid embryo´s developed. Pathological changes as an effect of decreased immunity. Are produced cancer tumors and lose of teeth.
Sea eagles have reproduction problems due to eggshell thinning, and also problem with their prey (fishes) due to the surplus of dioxins.
Contaminants such as heavy metals may cause evolutionary changes due to harmful effects on plants. Examples of heavy metals are copper (Cu), lead (Pb), zinc (Zn), mercury (Hg), arsenic (As), etc. Heavy metals are potentially polluting devastating because they pollute the air, water and land used by plants and other links in food chains. The contaminated substrates come usually from mining work, pollution, and foundry industry plating, using fertilizers and pesticides, and the deposition of sludge and sewage sludge.
Heavy metals is manifested mainly in the water, because of human activities, it's case many heavy metal in the soil and water, Like this, When Heavy metals enter the ecosystem, it will remain, accumulate and move .When the concentrations are too high, heavy metal will affect animal and vegetation for example, heavy metal can accumulate algae and substrate sludge, it also can absorb with shellfish and fish. Then, chemical in water will change and many creatures will dead or mutation if they eat, so food chain and ecosystem problem become serious. Heavy metal also could enter the water by industry discharge, many industry are built close to the Baltic Sea, its discharge many chemical substance, toxic and heavy included. Because heavy metals in water are difficult to resolve, it's also easy to accumulate. So heavy metal is irreversible, now, there are five heavy metals are more affect for the human, there are lead, cadmium, mercury, arsenic and chromium. In 1967, many rivers and
Swedish lakes were so contaminated by
mercury that fishing was banned there. Mercury is deposited on the floor of the lakes and slowly is converted by bacteria into compounds soluble mercury. These can be introduced into food chains. The problem is that metals cannot be chemically degraded.
Figure15: Map of cadmium emissions to air as totals in tonnes/year for the period 1990-2004.
Oil pollution is another of the serious problems in the sea. One example occurs in November 2002, the oil tanker Prestige collided with a floating container off the Spanish coast; it leads many tones of fuel oil in the sea. Because the sea breeze. This oil pollution cause four hundreds kilometer of coast and 179 beaches were polluted, ten thousand seabirds dead and lose a lot of money. Not only lose money but also destroy ecosystem
Oil in the sea will spread oil film. Normal condition, one ton oil form oil film can affect about 12 square kilometer areas. Oil film can reduce the power radiation from the sun. It also affects sea-plant photosynthesis and food chain directly, thus, destroys the ecosystem and eubiosis. In the other hand, oil pollution can lead oxygen-poor. Its mean many sea animal and plant will dead and reduce ability of its ingestion, propagation and growth. Influence the cell and make some animals variation.
Oil pollution has four main reasons to product the pollutant:
1. Stricken tanker
2. Oilcan burst
3. Refinery pollution discharge
4. Sea oil-well blowing
Now, government from each country has already set different rules to limit the ship, some ways for monitoring pollution is used frequently. for example, remote sensing. Its fast way for us to find the area where are polluted. In the other hand, technique improves also affect the ships, with the development of ship, oil pollution are decreasing.
Figure16: Reference: oil pollution Monitoring in the northem Baltic sea
All of these substances affect and are accumulated on the living organisms. In the Baltic, which have special conditions, we can find pollutants in plants and animals, some of them really important to the food chain.
Key-species are species that maintain crucial ecosystem functions, and a lot of others species depend of them. They are more important in the Baltic than in other ecosystems because Baltic Sea is quite sensitive to these changes. It could take thousands of years for the species once again to develop adaptations to the brackish water there as effective as those we find in the present Baltic Sea stock. So, if one key-specie disappears, the ecosystem is not able to survive reasonably intact. One example is the common mussel, which plays a key role in the food webs of the Baltic proper and the Bothnian Sea. If for some reason the common mussel were to disappear, fish production would probably decline markedly there as well. They also filter the water which contains plankton (control of the plankton quantity) and return nutrients to the water.
Figure17: Specific features and processes which make the Baltic Sea sensitive (green-natural characteristics, white-human impacts, yellow-harmful effects)
The most dramatic effect is in the food chain: most of species doesn't have food, even when normal levels of oxygen recover. Fresh water and poor oxygen waters doesn't mix. With high level of nutrients, dead zone is created. Permanent hypoxia has developed the anoxia (deficiency of oxygen) in big areas. That sea has lost around 30% of his food chain and it has decreased the efficiency of fisheries. If we removed dead zones, Baltic would be around 40% more productive. The only solution is to minimize the arrival of nutrients.
4. Discussion
Baltic as the large area sea, with the long time development, many animals and plants are suitable living here, but human activities destroy and make pollution in Baltic Sea. Many creature dead and ecosystem changed. Now, Baltic Sea can't recover, Creature extinguish, environment destroyed and sea area changed make us have to consider more about how to save the Baltic sea, how to save ourselves.
Obviously, human activities at the Baltic Sea and surrounding the sea affect the local environment seriously. Sustainable development in Baltic Sea is necessary. We have to make some measures to restrict ourselves, if that. We can ease the environment, even can solve. Here, there are some practical planes:
A set of policy, legal and regulatory reforms that can establish in each country.
Institutional strengthening and human resource development.
Improve the infrastructure and make some rules about reduce the pollutants discharge.
To aid in the management in the coastal.
Encourage public awareness and environmental education to develop a broad and sustainable base of support for implementation of the other components.
A serious problem we have to consider is that not all the country can establish the effective policy for obeying the rules. It's mean that different country has different national conditions. How to unify the policy is become more seriously rent years.
-How can we minimize that arrival of nutrients?-
Trees are big consumers of nutrients and the most important part of nutrients come from agriculture, so having big areas of trees near those agriculture areas, could be a good complement to decrease that amount of nutrients, before arriving to groundwater. Cutting the trees near agriculture areas is not interesting for groundwater.
Another option is to limit the number of animals that could be kept per hectare of arable land. But the most important factor is the arrival of fertilizers, so maybe governments have to prevent excessive their use or develop cleaner fertilizers.
Thanks to measures such as improved flue-gas cleaning. Sweden has reduced its emissions of dioxins and similar pollutants in recent years, but it is almost impossible to eliminate them altogether.
About mining, there are risks of long-term leaching from mine wastes The portion of the ore richest in metals in the concentration process is separated out and sent for smelting, but the remainder also contains some sulphide minerals; if these minerals are exposed to atmospheric oxygen they will gradually be converted into sulphuric acid and mineral salts than can easily migrate into nearby waters, turning its inmediate vicinity water acidic and contaminated with metals. It can be reduced covering the sulphide ore wastes with clay or submerged in order to cut off the supply of oxygen and thus slow down leaching of metals and sulphuric acid.
Conclusion
After our study, we obtain some conclusions about the Baltic Sea region. It is clear that this area is really polluted and now, after studying natural characteristics, human impact and harmful effects we recognize where pollutant comes from and the difficulty of remove them.
First of all, natural conditions of this sea are not really good because it can't depurate quickly its harmful substances and another that comes from human activities. Maybe another sea like Mediterranean Sea could have the same quantity of eutrophication, heavy metals or human factors. But the natural conditions of Mediterranean Sea are better than Baltic Sea so we cannot see that effects.
Policies and actions become more important for human, Because of human activities, Baltic Sea can't recover. Though we had already done many of things to change the current situation, it does only can reduce the destruction of environment. We also learn look the environment problem from the scientific point in our daily life. Environment problem could be the endless topic for human, once we keep a slack hand.
Environment problem will affect us soon. Like the Baltic Sea.
