Ngư nghiệp - Marine pollution

GOOD MORNING CLASS!上午好学生们！Shang wu hao xue sheng men!videoMarine PollutionProblem:Pollution of the world's oceans is quickly becoming a major problem on Earth. We know very little about the effect that pollution has on the oceans but we continue to dispose of chemicals, sewage and garbage into it. Marine pollution"Introduction of man, directly or indirectly, of substances or energy into the marine environment (including estuaries) resulting in such deleterious effects as harm to living resources, hazard to human health, hindrance to marine activities including fishing, impairment of quality for use of sea-water, and reduction of amenities.” – GESAMP DefinitionImpacts on living resourcesHazards to human healthHindrance to marine activitiesImpairment of quality of seawaterReduction of amenitiesLoss of aesthetic beautyImpacts on the sensitive habitats General impactsMarine pollutionContd..Pollution in coastal waters• Coastal waters especially are highly affected by pollution because they are:– Heavily used– Close to sources of pollution– Shallow-water bodies– Not as well circulated as the open ocean• Coastal pollution is made up of marine pollution and marine debrisSources of pollutionLand-based sources Agricultural run-off Municipal and industrial wastesSea-based sources Oceanic dumpingOffshore oil spillsPoint and Non-Point SourcesPoint source – refers to a single identifiable source of pollutants eg. effluent outfallNon-point source – refers to diffuse source of pollutants eg. Acid rain, dust stormsNONPOINT SOURCESPOINT SOURCESUrban streetsSuburban developmentWastewater treatment plantRural homesCroplandFactoryAnimal feedlotContd..Discrete vs. Chronic PollutionDiscrete (short term) – eg. an oil spill, the effects of which diminish with timeChronic (long term) – eg. nutrient input, effluent dischargeTypes of pollutionTypes of pollutionPollutionOil(Petroleum hydrocarbons)EutrophicationConservativeMetalsHalogenated hydrocarbonsThermalRadioactiveLitter & Plastic debrisContd.. Oil pollutionOil pollution is mostly used to describe marine oil spills, where oil is released into the ocean or coastal waters. Oil spills are due to the following:crude oil from tankersoffshore platformsdrilling rigs and wellsspills of refined petroleum products (such as gasoline, diesel) spill of any oily refuse or waste oilSources of Oil Pollution Oil pollution SourcesContd..Source: UNEPWhen oil is spilled on sea it spreads over the surface to form a thin film – called oil slickLight oil spreads faster than heavy wax oilLow molecular weight fractions evaporateWater soluble components dissolveNon-water soluble components emulsify and forms a viscous mass – “chocolate mousse”Heavy residues form tar balls Oil pollution FateContd..Chocolate mousseTar balls Oil pollutionFateContd..Some Major Oil Spill CatastrophiesThe Components and Effects of OilEffects – Impairment of marine lifePlankton, esp. neuston at highest risk – exposed to water soluble components leaching from oilFixed vegetation –Sea grass beds– killed or flowering inhibitedIn Mangroves – lenticels clogged with oil oxygen level in sediments drops – deathSea birds –buoyancy and thermal insulation lost Oil pollutionImpactsContd..Commercial damageMortality of fish, reduction in catchDeath of fish eggs and larvaeTourism – becomes nuisance – avoided by beach goers – loss of revenueLoss of sensitive marine habitats – loss of flora and fauna Oil pollution ImpactsContd..Cleaning-up oil spills:1. Dispersants: Oil can be broken down more quickly by spraying dispersants (chemicals) on the oil slick from boats or planes. This method only works on fresh, small oil spills.2. Booms: A boom has a floating skirt suspended down in the water and a sail holding it above the water line. The floating skirt stops the oil from passing. These are used to prevent oil from entering delicate and protected areas.3. Slick-lickers: This method uses a belt of oil absorbing material that sucks up the oil from the ocean water. The oil is then squeezed out of the absorbing material into a collecting bin.24Akpe na mi!Eutrophication“The enrichment of water by nutrients, especially nitrogen and/or phosphorus, causing an accelerated growth of algae and higher forms of plant life to produce an undesirable disturbance to the balance of organisms present in the water and to the quality of water concerned” - OSPAR (Oslo/Paris convention for the Protection of the Marine Environment of the North-East Atlantic)EutrophicationWastewater effluent (municipal and industrial)Runoff and leachate from waste disposal systemsRunoff from agriculture/irrigation Runoff from pasture and rangeRunoff from mines, oil fields, unsewered industrial sitesOverflows of combined storm and sanitary sewersUntreated sewage SourcesContd..Over-productivityReduction in phytoplankton species diversity Growth of harmful algal bloomsReduction in dissolved oxygen contentAnoxia and mass mortalities of marine organismsContd.. ImpactsEutrophicationGlobal map of dead zones related to human-caused eutrophication (Scientific American, 2008)Contd..EutrophicationAn example of Marine outfalls in Tarut Bay Safwa STPSanabis STP Awamiya STP & Nasira Agricultural Jaruadiyah STP Majidia Agricultural Discharge Anak North Agricultural Discharge Anak South Agriculture discharge Contd..EutrophicationConservative pollutants - MetalsA heavy metal is a member of a loosely-defined subset of elements that exhibit metallic properties. It mainly includes the transition metals, some metalloids, lanthanides, and actinides. There is an alternative term for heavy metal and is called as toxic metalThe major sources of metals are:Natural sourcesManmade sourcesErosion of ore-bearing rocksAtmospheric inputs - wind blown dustVolcanic activityForest firesRiverine inputs into oceansConservative pollutants - MetalsContd.. Natural SourcesIndustrial discharge SewageRe-suspension of sediments by dredging and trenchingConservative pollutants - MetalsContd.. Manmade SourcesMetalNatural sources(in thousand tonnes/year)Anthropogenic sources(in thousand tonnes/year)Arsenic1218Cadmium1.37.6Copper2835Lead12332Nickel3056Zinc45132World-wide emissions (Clark, 2001)Conservative pollutants - MetalsContd..Arsenic (As) Phytoplankton most sensitive & accumulate from water columnHigher trophic levels accumulate via food.Cadmium (Cd)Divalent cadmium is more toxicTends to bioaccumulateLead (Pb)Forms strong complex with clay and suspended materialBioaccumulates in most marine organisms – no significant problems.Conservative pollutants - MetalsContd..ImpactsAn example of Mercury pollution in Minamata Bay, Japan (1953-1960)SourcePollution from plastic plant- dumped mercuric chloride into the bayImpactShellfishes contaminated with mercuryPeople who consumed shellfish severely affected43 dead and 700 permanently disabledBay is still unusable for fishing and shell fishingConservative pollutants - MetalsContd..Impacts of metal pollution by Bioaccumulation and BiomagnificationBioaccumulationIncrease in concentration of a substance(s) in an organism or a part of that organismThe affected organism has a higher concentration of the substance than the concentration in the organism’s surrounding environment Not excreted or metabolised and failure of the target organ Also called bioamplification Increase in concentration of a substance in a food chain, not an organismBiomagnificationHydrocarbons containing chlorine, fluorine, bromine or iodineDiffers from petroleum hydrocarbons – not degraded by chemical oxidation or by bacteriaLow molecular weight compounds – eg., Dichloroethane, Freons etc. High molecular weight compounds – eg., DDT, Drins, PCBsConservative pollutants – Halogenated hydrocarbonsAerial transportAerial spraying of pesticides as aerosols – travel great distancesFreshwater inputsRain washing of pesticides carried into sea by riversSilt from flood Direct inputsBy industrial outfalls – especially by Pesticide manufacturing companies. SourcesContd..Conservative pollutants – Halogenated hydrocarbonsLow solubility in water persist for long durationsFat-soluble , so incorporated into the tissue of marine organisms and sedimentsLethal to the animal Possibility of transmission through food webs – established in a number of animals ImpactsContd..Conservative pollutants – Halogenated hydrocarbonsThermal pollutionThermal pollution is the degradation of water quality by any process that changes ambient water temperature.Outfall from Qurrayah power plant, Saudi ArabiaThermal pollution SourcesIndustrial wastewaterPower plant dischargesDesalination plant dischargesUrban runoffContd..Thermal shock Decrease in dissolved oxygenIncrease in photosynthesisIncrease in metabolic rate of fishIncrease in oxygen consumptionThermal pollution ImpactsContd..Radioactive pollutionRadioactive wastes are usually by-products of nuclear power generation and other applications of research and medicine. Radioactive waste is hazardous to human healthPollution due to radioactive wastes – Radioactive pollutionWeapons testing – Testing of nuclear weapons – when exploded underwater release fission products and isotopesLiquid wastes – Discharge from the cooling water of nuclear reactorsSolid wastes – Dumping of radioactive wastes in Sea (now no longer practiced).Radioactive pollution SourcesContd..Highly lethal - Even low doses causes fatal damagePossibility of bioaccumulation – especially in algae and bivalves eg. Porphyra near a nuclear power plant location had 10 times more caesium-137 than in the surrounding watersRadioactive pollution ImpactsContd..Marine Garbage Garbage includes junked out fishing nets, plastics, general household garbage In one case an island 300 miles from the nearest inhabited island) had 950 pieces of garbage ranging from plastics to tin cans.Garbage in the oceans is a serious issue as fish entangle themselves in fishing nets and animals sometimes eat trash products and die. There are numerous examples each year of dolphins, sharks and whales entangling themselves in fishing nets and dying from oxygen starvationLitter and Plastics pollutionMarine litter, is human created waste that has deliberately or accidentally become afloat in a the sea or ocean.It tends to accumulate at the centre of gyres and on coastlines, frequently washing aground, when it is known as beach litter or tidewrack. Litter and Plastics pollution SourcesUp to 80% of the pollution is land-based.A wide variety of anthropogenic artifacts can become marine debris Plastic Bags, Balloons, Buoys etc.Contd..Litter and Plastics pollution ImpactsMany animals that live on or in the sea consume flotsam by mistake, as it often looks similar to their natural preyBlocks the passage of food and causing death through starvation or infection.Tiny floating particles also resemble zooplankton, which can lead filter feeders to consume them and cause them to enter the ocean food chain. In samples taken from the North Pacific Gyre in 1999 by the Algalita Marine Research Foundation, the mass of plastic exceeded that of zooplankton by a factor of six.Contd..Solution to pollutionReduce input of toxic pollutantsTreat sewage primary, secondary and tertiary treatmentBan dumping of wastes and raw sewage in nthe sea Ban ocean dumping of sludge and hazardous dredged materialProtect sensitive areas from development, oil drilling, and oil shippingRegulate coastal developmentThank you