Transcript MARINE POLLUTION Pollutant Hazards

CIV 913 Environmental Assessment and
Sustainability
ESTUARINE AND MARINE
POLLUTION
ESTUARIES
• Definition.
– A semi-enclosed coastal body of water which has
a free connection with the open sea, and within
which sea water is measurably diluted with fresh
water derived from land drainage.
ESTUARIES
• Mixing is a function of:
– River flow
– Tidal Volume
– Width and Depth of the Estuary.
ESTUARIES
• Characteristics of Mixing
– Stratification (Depends on shape and flows)
• Denser sea water flows upstream in a wedge
shape.
• River water flows out to sea over the top of the
sea water.
ESTUARIES
• Mixing Characteristics.
– Least mixing when QFW >> Qsea
– Stratification causes a salinity gradient.
– Stratification results in higher velocities than in the
highly mixed estuary.
– A vertical salinity gradient results in the upstream
movement of sediment.
ESTUARIES
• Flow
– Due to tides net seaward movement may be small
– e.g. Thames.
• downstream flow high to low water - 15km
• upstream flow low to high water - 13 km
• net seaward flow - 2 km per tidal cycle.
ESTUARIES
• Residence Time
– Can be long eg 30days in the Thames estuary.
– Thus dilution capacity is correspondingly reduced.
– More pronounced oxygen sag.
– Affects migratory fish and macroinvertebrates.
ESTUARIES
• Sedimentation.
– Important characteristic of estuaries.
• elevated by salt / freshwater mixing
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Sedimentation of suspended matter.
Flocculation and sedimentation of e.g. clays
Absorption of metals.
Sedimentation of organic matter from river,
material from the sea (and dredging) and waste.
– Sediment Oxygen Demand (SOD)
Marine Pollution
MARINE POLLUTION
Types of Pollution
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Organics
Solids
Pathogens
Metals
Halogenated Hydrocarbons (e.g. PCBs)
Oil
Radioactivity
MARINE POLLUTION
Inputs
• Atmospheric deposition
• Rivers
• Direct outfalls
– Sewage
– Industrial
• Solids disposal
• Shipping
MARINE POLLUTION
Contamination and Pollution
Pollution.
– The introduction by man, directly or indirectly, of
substances or energy to the marine environment,
resulting in deleterious effects such as:
• hazards to human health
• hindrance of marine activities
• impairment of quality (in terms of use) of
seawater
• reduction of amenities.
MARINE POLLUTION
Inputs
• Many inputs are not deliberate:
– Vegetation and dead organisms from rivers
– Mercury from volcanoes
• e.g 5000 to 25000 tpa from volcanoes and weathering of
mercury-bearing ores.
• 8000 tpa from industry and burning fossil fuels.
• Hence knowledge of background concentrations
important.
MARINE POLLUTION
Regulation
• International Conventions
– North Sea (Oslo, Paris, North Sea)
– Baltic (Helsinki)
– Mediterranean (UNEP/Barcelona)
– Regional Seas programme (UNEP)
• Scientific Committees recommend areas for
monitoring and control.
MARINE POLLUTION
Oil
• Sources of Oil to the Marine Environment.
Source
Anthropogenic
Transportation
Fixed installations
Municipal & Industrial WWT
Urban & river run-off
Atmospheric fallout(oil-derived)
Natural
Marine phytoplankton
Atmospheric fallout
Estimate (m tpa)
1.47 (0.568 spills)
0.17
0.90
0.12
0.3
36,000
220
MARINE POLLUTION
Oil
• Effects of Weathering on an Oil Slick
Evaporation
Rapid (24hr)
Dissolution
Fairly rapid
Dispersion
Rapid early stages
Emulsification
Rapid early stages
Photochemical oxidation
Dependent on light
Adsorption
Dependent on SS
Biodegradation
Fairly rapid early
stages.
MARINE POLLUTION
Oil
• Types of Damage to Marine Organisms.
Organism
Damage
Plankton
Seaweed
Invertebrates
Fish
Birds
Marine mammals
Possible growth inhibition of
phytoplankton.
Major Damage to inter-tidal
species. Rapid recovery. Excessive
growth if grazers badly affected.
Large scale mortality due to toxicity
and smothering.
Minor effects.
Diving birds badly affected.
Rarely affected. Coastal populations
vulnerable.
MARINE POLLUTION
Oil
• Treatment Techniques.
Process
Comment
Chemical
Dispersion enhances degradation.
Protects coasts but increases acute
toxicity.
Containment
Small spills, enclosed/calm waters
Recovery
Small spills, calm waters. Disposal
problems.
Adsorption/sinking Short term protection/long term
benthic contamination.
Burning
Fresh oil. Leaves tarry residues.
MARINE POLLUTION
Sewage Sludges
• UK ceased disposal of sewage sludge to sea.
• Need to consider hydrodynamics of the disposal site
– dispersive (low concentrations, but larger area
affected). Typical for UK.
– accumulating ( local effects/monitoring)
• Typically reduces diversity, but increases biomass in
the benthic community
MARINE POLLUTION
Monitoring
• Chemical and Biological
– Biological - Population Change
• Key species i.e high conservation interest,
commercial value, those whose presence or
absence has major repercussions on the
community.
• Indicator species.
– Biological - Community Response
• Preferred. Avoids errors due e.g. to climatic
changes.
MARINE POLLUTION
Monitoring
• Limitations of Toxicity Testing of Marine Pollution
– valency changes, alter form.
– metal salt solubility. (Lead citrate>>Lead nitrate)
– organic complexes of heavy metals>>inorganic
compounds eg mercury (but NOT arsenic)
– oil (dissolved and particulate components)
– chlorinated hydrocarbon pesticides
• low solubility in water, particulate ingestion important
MARINE POLLUTION
Monitoring
• Sub-Lethal Effects and Biomarkers
– Non-specific pre-cancerous growths on flatfish (e.g.
observed for sewage sludge, oil and titanium dioxide).
– Skeletal deformities in fish e.g. herring affected by
chlorinated hydrocarbons, oils and heavy metals.
– Detoxification mechanisms
• formation of metalothioneins to complex metals (urchins,
crabs, seals, rockfish)
• production of mixed function oxygenases in livers of fish
due to exposure to lipophilic organic compounds
MARINE POLLUTION
Monitoring
• Analysis of Community Responses.
– Use soft sediment invertebrates.
– Diversity
• Univariate analysis e.g. number of species per unit area,
• Graphical methods e.g. abundance-biomass comparison
(comparison of sites, but does not differentiate the actual
species).
– Species composition.
• Multi-variate statistical analysis e.g. comparison of
similarities of species in different samples.
MARINE POLLUTION
Pollutant Hazards
• Sewage and Sewage Sludge
– Affects coastal waters.
– Reduced diversity, increased biomass in
sediments.
– Can get oxygen depletion e.g. New York Bight, the
German Bight and some Norwegian fjords.
– Nutrient addition - Eutrophication.
– Changing nutrient balance affects distribution of
plankton, and can stimulate production of toxins.
MARINE POLLUTION
Pollutant Hazards
• Sewage and Sewage Sludge
– Direct infection, and contamination of sea food.
• Most terrestrially derived bacteria and viruses die
within 12-24hrs in the sea.
– due to UV, high salt concentrations, low concentrations of
antibiotic inorganic and organic chemicals.
• Some enter a dormant phase, not measured in
routine tests. Can become active when ingested by
bathers.
– Control bathing and shellfish waters.
MARINE POLLUTION
Pollutant Hazards
• Persistent Organic Compounds.
– e.g. List I Substances. Persistence, bioaccumulation
potential and toxicity.
– Few studied in the marine environment e.g. halogenated
compounds.
• organochlorine pesticides (DDT, dieldrin, aldrin and
endrin, lindane, hexachlorobenzene). Lipophilic.
• Banned in developed economies.
• Still widespread in emerging and developing economies
due to low cost.
– Dioxins.
– 2,4,5 Trichlorophenoxyacetic acid (Agent Orange)
– PCBs. Type important. Coplanar most toxic. Effects sublethal. Widespread in the marine environment.
MARINE POLLUTION
Pollutant Hazards
Persistent Organic Compounds
• Effects.
– Primary production rates of plankton reduced at >
1 mg/l
– Fish 96 hr LC50 1-100mg/l
– Typical concentration in seas at pg/l and ng/l
levels i.e. much below the acute concentrations.
– Effects mainly eggshell thinning in birds and
reproductive abnormalities in mammals eg seals
in the North and Baltic seas.
MARINE POLLUTION
Pollutant Hazards
• Distribution of PCBs Between Different
Environmental Compartments.
Environment
PCB Load(t)
% of Load
Land&Coast
Sediment
130000
35
Sea Water
2400
0.64
Other
10700
2.6
Open Ocean
Sea Water
230000
61
Sediment
110
0.03
Other
1060
0.73
MARINE POLLUTION
Pollutant Hazards
• Trace Metals
– Take account of metal speciation and condition of organism.
– Mercury
• Important marine species: Elemental, divalent and methyl
mercury.
• Key factors
– high affinity for organics, hence accumulates in
marine biota.
– inorganic mercury may be bio-converted to methyl
mercury.
– Accumulates in fine-grained coastal sediments.
MARINE POLLUTION
Pollutant Hazards
• Lead
– Main inputs to the sea are from the air.
– Long range effects due to this airborne pathway
– Main effects seen in coastal environments with a
build-up of lead in sediments.
– Lead in the marine environment presents a
negligible source to humans.
MARINE POLLUTION
Pollutant Hazards
• Tin
– A potentially serious marine pollutant.
– Organotin compounds provide the hazard (e.g. tributyl tin oxide TBTO)
– Main uses, PVC stabilisers and biocides (antifoulants on ships)
– Two main sources
• bacterial methylation of inorganic tin.
• leaching of aryl and alkyl tin from ant-fouling
paints.
MARINE POLLUTION
Pollutant Hazards
• Tin (contd)
– Harmful responses in a number of marine
organisms.
– Commercial stocks e.g. Pacific oysters,
dogwhelks, farmed slamon.
– Concentrations believed to affect shellfish
– 0.01 ug/l
– Causes reduced growth in young POs and
loss of fertility in female DWs
MARINE POLLUTION
Pollutant Hazards
• Tin (contd)
– Acutely toxic to planktonic organisms. e.g.
mollusc larvae at 1.0mg/l
– Banned in mariculture installations and on boats
< 25 m in EU, USA, Australia, NZ
– Rapid recovery (few years) of dogwhelks following
the ban.
MARINE POLLUTION
Pollutant Hazards
• Radionuclides
– natural potassium-40
– detectable at great distance from discharge
– accumulation in sediments
– local ecological impact
• bottom dwelling fish
• shellfish (human health risk)
– international pressures on nuclear industry
• Sellafield
MARINE POLLUTION
Pollutant Hazards
• Conclusions.
– Widespread anthropogenic effects can be
detected, even in remote regions.
– Main impacts are in coastal waters.
– Control of risks associated with marine
pollution is increasing, but still has a long
way to go.