Lecture 1. Introduction to Agricultural Pollution Control Including particular reference to Eastern and Central Europe Prepared by Assoc. Prof. Philip Chiverton, SLU
Pollution : ‘the introduction by man, directly or indirectly, of substances or energy into the environment, which are liable to create hazards to human health, to harm living resources and marine ecosystems’ Agricultural pollutionis, thus, the direct or indirect introduction of substances – particularlyexcessive nutrients(such as nitrates (N) and phosphorous (P) )- or energy into the environment as a result of mans agricultural activities.
Eutrophic means nutrient-rich, and eutrophication literally means enrichment with nutrients, although nowadays the term is more often used in a negative sense to mean over-enrichment. Nutrients - especiallynitrogenand phosphorus - are vital for marine life. But the presence of excessive nutrients can seriously disturb the functioning of marine ecosystems.
Excessive nutrient inputs into a water body induce biological, chemical and physical changes in aquatic plant and animal communities, often leading to oxygen depletion, especially in deeper waters. Greenish, murky water is typically the first sign ofeutrophication as microscopic plants and algae grow profusely, consuming the surplus nutrients. But algae are short-lived, and when they die they sink to the bottom of the sea, where their decomposition uses up oxygen. The worst affected areas can become completelyanoxic. In the absence of oxygen, decomposition can release toxichydrogen sulphide, poisoning organisms and making the sea-bed lifeless.
Bluegreen algal blooms, Gulf of Finland Photos from: Finnish Institute of Marine Research (http://www2.fimr.fi/en/itamerikanta/galleria/15.
Weather conditions can alleviate or accelerateeutrophication. Mild, wet winters are usually bad news for shallow, coastal waters, as nutrients are washed from farmland into rivers, lakes and ultimately the sea. This creates suitable condition for intense algal blooms in the spring, which can lead to serious oxygen depletion, especially if the summer is then warm and calm.
Bluegreen algal bloom, Gulf of Finland 6th August, 2002 Photos from: Finnish Institute of Marine Research (http://www2.fimr.fi/en/itamerikanta/galleria/15.
Algal bloom on the Fyris River near SLU in Uppsala – the river drains the intensively cultivated agricultural plain of Uppland
So the rivers and seas turn green for a while – Who cares!?!
There are many reasons why governments and authorities throughout the world are deeply concerned about the effects of agricultural pollution. Not least is the danger to • Public health. In drinking water, high concentrations of • nitrate can cause methemoglobinemia, a potentially fatal • disease in infants also known as blue baby syndrome. • Fish stocks and marine biodiversity. Eutrophication destroys • (a) spawning areas for economically valuable fish, and • (b) habitats for other marine life. • The tourist industry. Poisonous and/or unsightly and odorous • coastal waters discourage tourists!
Problems and causes - a summary • Nutrientover-enrichment of coastal ecosystems generally triggers ecological changes that decrease the biological diversity of bays and estuaries • While moderate N enrichment of some coastal waters may increase fish production, over-enrichment generally degrades the marine food web that supports commercially valuable fish. • The marked increase in nutrient pollution of coastal waters has been accompanied by an increase in harmful algal blooms, and in at least some cases, pollution has triggered these blooms.
Problems and causes cont’d • High nutrient levels and the changes they cause in water quality and the makeup of the algal community are detrimental to the health of coral reefs and the diversity of animal life supported by seaweed and kelp communities. • Research during the past decade confirms that N is the chief culprit in eutrophication and other impacts of nutrient over-enrichment in temperate coastal waters, while P is most problematic in eutrophication of freshwater lakes. • Human conversion of atmospheric N into biologically useable forms, principally synthetic inorganic fertilizers, now matches the natural rate of biological N fixation from all the land surfaces of the earth.
Problems and causes cont’d • Both agriculture and the burning of fossil fuels contribute significantly to non-point flows of N to coastal waters, either as direct runoff or airborne pollutants. • N from animal wastesthat leaks directly to surface waters or is volatilized to the atmosphere as ammoniamay be the largest single source of N that moves from agricultural operations into coastal waters.
How do different agricultural activities contribute to pollution, and how does this affect our ground and surface waters??
Agricultural impacts on water quality 1. Tillage/ploughing Agriculturalactivity Impacts Surface waterGroundwater Sediment/turbidity: sediments carry phosphorus and pesticides adsorbed to sediment particles; siltation of river beds and loss of habitat, spawning ground, etc.
2. Fertilizing Agricultural activity Impacts Surface waterGroundwater Runoff of nutrients, especially phosphorus, leading to eutrophication causing taste and odour in public water supply, excess algae growth leading to deoxygenating of water and fish kills. Leaching of nitrate to groundwater; excessive levels are a threat to public health.
3. Manure spreading Agricultural activity Impacts Surface waterGroundwater Contamination of ground-water, especially by nitrogen Carried out as a fertilizer activity; spreading on frozen ground results in high levels of contamination of receiving waters by pathogens, metals, phosphorus and nitrogen leading to eutrophication and potential contamination.
4. Feedlots/animal paddocks Agricultural activity Impacts Surface waterGroundwater Contamination of surface water with many pathogens (bacteria, viruses, etc.) leading to chronic public health problems. Also contamination by metals contained in urine and faeces. Potential leaching of nitrogen, metals, etc. to groundwater.
Agricultural activity 5. Irrigation Impacts Surface waterGroundwater Enrichment of groundwater with salts, nutrients (especially nitrate). Runoff of salts leading to salinization of surface waters; runoff of fertilizers and pesticides to surface waters with ecological damage, bioaccumulation in edible fish species, etc. High levels of trace elements such as selenium can occur with serious ecological damage and potential human health impacts.
6. Clear cutting Agricultural activity Impacts Surface waterGroundwater Disruption of hydrologic regime, often with increased surface runoff and decreased groundwater recharge; affects surface water by decreasing flow in dry periods and concentrating nutrients and contaminants in surface water. Erosion of land, leading to high levels of turbidity in rivers, siltation of bottom habitat, etc. Disruption and change of hydrologic regime, often with loss of perennial streams; causes public health problems due to loss of potable water.
7. Silviculture Agricultural activity Impacts Surface waterGroundwater Broad range of effects: pesticide runoff and contamination of surface water and fish; erosion and sedimentation problems.
8. Aquaculture Agricultural activity Impacts Surface waterGroundwater Release of high levels of nutrients to surface water and groundwater through feed and faeces, leading to serious eutrophication.
So, we have a problem and the authorities are aware of it. What policies exist within e.g. the European Union to alleviate the problem?
Ironically the EU’s Common Agricultural Policy has tended to exasperate the problem! A recent study carried out by the European Nature Heritage Fund concluded that: ’most of the EU’s agricultural subsidies exert a negative impact on the environment, for the majority of payments to farmers are not tied to any environmental regulations’ Over 60% of the agriculture budget’s total 44 billion Euro’s currently go to the arable crops sector, and these subsidies are not tied to environmental regulations
Grassland - so important for biological diversity and forage cropping – is excluded from the payments. Maize, on the other hand, is heavily subsidized such as no other crop, and ecologically it is highly problematic because especially large amounts of fertilizer are used in maize farming. In Germany this has lead to a massive increase in maize farming, and at least 25% reduction of meadows and pastures over the past twenty years.
Agricultural water pollution issues surfaced in connection with the 1980 EU directive on drinking water, which required member states to ensure that certain quality objectives for drinking water were met by 1985. But, during the second half of the 1980’s, it became clear that most member states had not achieved these quality objectives. In particular, the maximum pollutant level for nitrate in drinking water, set at 50 mg per liter, was exceeded in many areas.
We will see later that further reforms to the CAP in the late 1980’s (that offered subsidies to farmers who reduced livestock density, decreased fertilizer use or switched to organic farming or other extensive forms of production), some National control measures introduced by individual member states, and the introduction in 1991 of the Nitrate Directive, are having some effects. Annex 11 of the Nitrate directive outlines Code(s) of Good Agricultural Practice with the objective of reducing pollution by nitrates.
For some Candidate countries and Newly Applied States problems regarding agricultural pollution of water are compounded by the lack of a good Agricultural Advisory Service infrastructure.
Let us now examine the situation in and around our respective seas i.e. The Baltic Sea and The Black Sea
I’ll start with the sea nearest home which of course is The Baltic sea
Farming the land can pollute the sea During recent decades the Baltic Sea has been burdened with increasing inputs ofnutrientsfrom agricultural sources such as manure and fertilisers. The consequenteutrophication has widely disrupted marine ecosystems. There have been reductions in the most harmful agricultural emissions, butfarmland remains one of the main sources of the surplus nutrients entering the Baltic Sea.
The environmental quality of the Baltic Sea is largely influenced by the inputs of pollutants - particularly excessive nutrients Nutrientscan enter the sea in runoff from arable land, mainly via rivers and streams, but also along coasts; or in the form of deposition from the air. More than 25 of the 132 serious pollution hot spots identified around the Baltic Sea since 1992 have already been cleaned up.
http://maps.grida.no/scripts/esrimap.dll?name=hotspots&cmd=map.htmlhttp://maps.grida.no/scripts/esrimap.dll?name=hotspots&cmd=map.html Follow the above link to access an interactive map with details of all the knownHOT SPOTSin the Baltic sea drainage basin.
Marine Research Vessel on the Baltic Sea Photos from: Finnish Institute of Marine Research (http://www2.fimr.fi/en/itamerikanta/galleria/15.html)