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Lesson #13 Humans and the ocean: Pollution. Vernon Asper USM. The Human Presence in the Ocean. In this chapter we will focus our attention on some of the ways in which humans are stressing and disrupting marine ecosystems. We will first define pollution and then consider: Hydrocarbons

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Lesson #13 Humans and the ocean: Pollution


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    1. Lesson #13Humans and the ocean: Pollution Vernon Asper USM

    2. The Human Presence in the Ocean • In this chapter we will focus our attention on some of the ways in which humans are stressing and disrupting marine ecosystems. We will first define pollution and then consider: • Hydrocarbons • Municipal and Industrial Effluent • Coastal Development • Ocean Dredging and Mining • Debris

    3. Pollution • Pollution is the introduction by humans, directly or indirectly, of substances or energy into the marine environment (including estuaries) resulting in deleterious effects • Effects include: • harm to living resources • hazards to human health • hindrance of marine activities • (including fishing) • impairing quality of sea water

    4. Pollution (Cont.) Some pollutants in the ocean also may be present because of natural causes. TABLE 12-1 Some pollutants in the ocean. Natural Sources Seeps, rivers, volcanoes, atmosphere, bacteria Volcanoes, rivers, sediments, weathering of rocks Rivers, upwelling, atmosphere, bacterial decomposition None Pollutant Hydrocarbons Heavy metals Nutrients Synthetic chemicals Human Sources Transportation, production, aerosols Industrial and municipal effluents Municipal effluents, agricultural fertilizers Manufacturing, transportation, agricultural fertilizers, and pesticides Source: Adapted from R.A. Geyer, ed., Marine Environmental Pollution, I Hydrocarbons NY, Elsevier Scientific Publishing Company, 1980).

    5. Pollution • Pollutants tend to be concentrated in three parts of the ocean. • The sea bottombecause they chemically attach to silt and clay sized particles. • Along pycnoclines, especially in estuaries because the particles are trapped by the density discontinuity. • At the surface where conditions promote particle aggregation.

    6. Pollution • A commonly held belief is that the ocean’s capacity for accepting human refuse and for self-cleansing is limitless. • It is not. • The coastal ocean has a finite, natural capacity that in many cases has already been exceeded.

    7. Pollution • The most seriously polluted region is the coastal zone that borders large urban centers. • However, even the open ocean is showing signs of pollution. Areas that coincide with the major shipping channels are showing signs of contamination.

    8. Pollution • Since the ocean is a dynamic system and water is exchanged regularly no part of the ocean and for that matter the Earth is truly free of human influence. • All nations must work together to develop regulations to protect the environment.

    9. Pollution • The human population already at 5.4 billion people is expanding at an exponential rate. • This growth rate will place increasing pressure on the environment. • It is essential to protect the Earth system from unnecessary degradation. • As individuals we can make a difference if we choose a lifestyle that mitigates harm of the Earth’s ecosystems.

    10. Hydrocarbons • Hydrocarbons are volatile compounds composed of hydrogen and carbon (hence the name) • The C-H bond is strong and, when it is broken, energy is given off. • Hydrocarbons burn • The hydrocarbons we’ll talk about are natural but many are not. www.its.caltech.edu

    11. Mineral Resources: Oil and Gas • Oil and gas are hydrocarbons derived from sedimentary rocks • these were deposited in quiet, productive regions with anoxic bottom waters in which the remains of phytoplankton accumulated. • Oil does NOT come from dead dinosaurs!

    12. Mineral Resources: Oil and Gas • Deep burial results in high temperature and pressure • This converted the organic remains into hydrocarbons. • Initially oil, but at higher temperatures and pressures, natural gas (methane, CH4) is generated.

    13. Mineral Resources: Oil and Gas • Pressure forces the oil and gas from the source rock into water-filled porous and permeable strata above. • Because they are lighter than water, they continue to migrate upwards. • If an impermeable (cap rock) is present above, the oil and gas are trapped.

    14. Mineral Resources: Oil and Gas • This is a simple picture of what the formations look like • Actually much more complex • Imagine this in 3-D • The challenge is to find these formations • And even then, there is no guarantee that there will be oil

    15. Mineral Resources: Oil and Gas • Location of possible accumulations of oil and gas can be determined using seismic reflection and refraction methods to determine the configuration of rock layers.

    16. Mineral Resources: Oil and Gas • The only way to know for sure if a formation holds oil is to drill it and find out • This requires the construction of huge drilling rigs like these

    17. Mineral Resources: Oil and Gas • Once the oil is discovered, it must be “produced” • This involves a production platform which pumps the oil into tanks which are periodically unloaded • During this operation, “useless” but dangerous gas is “flared off”

    18. Mineral Resources: Oil and Gas • In many parts of the Gulf, virtual cites of production platforms are set up

    19. Mineral Resources: Oil and Gas • The rigs provide a hard “substrate” for things to grow on. • That these “things” attract fish which like to eat them • VERY good fishing around the rigs

    20. Risks • Katrina and Rita destroyed 113 platforms and damaged 457 pipelines

    21. The BP spill of 2010 was enormous but: • Deep water: much of it never reached the surface • Far from shore: much oil was degraded before it reached the sensitive coastal habitats.

    22. Hydrocarbons in the Sea (Cont.) • Petroleum (cont.) • Oil can be light or dense depending on it’s size. The different types have different boiling properties. • In the process of refining, crude oil is heated and the different fractions are separated out to give rise to kerosene, diesel fuel, gasoline, and other petroleum products.

    23. Hydrocarbons in the Sea (Cont.) • Much of the oil pollution in the ocean occurs when petroleum is transported from where it is pumped out of the ground to where it is refined and consumed. • This is mostly due to “standard operational discharge” related to pumping bilges and ballasting ships. • Relatively little pollution occurs due to tanker accidents (like the Exxon Valdez).

    24. Hydrocarbons in the Sea (Cont.) • A substantial amount of oil is supplied by rivers which carry untreated domestic and industrial wastes to the sea. • Natural inputs of oil originate with phytoplankton and sea bed seeps.

    25. Hydrocarbons in the Sea (Cont.) • At these natural seep sites, communities of organisms grow which depend on the oil and gas • These include tube worms, mussels and other specialized creatures

    26. Hydrocarbons in the Sea(Cont.) • Oil released by humans usually occurs at the surface, far away from where these communities can deal with it.

    27. Hydrocarbons in the Sea (Cont.) • The rate of dissipation of an oil spill by natural processes depends on it’s specific composition, the weather, and the strength of surface currents. • Light fractions tend to evaporate. • Water soluble fractions dissolve and are mixed downwards by turbulence. • Heavy fractions form globules and tar-balls.

    28. Hydrocarbons in the Sea (Cont.) • Oil compounds are toxic to marine organisms. • The effect of a spill depends on the habitat. TABLE 12-3 The environmental impact of oil spillage. (1 of 4) Recovery Moderate to slow: Persistence of oil prolongs toxicity. Biological succession occurs at a moderate rate once oil is removed. Initial impact Heavy: widespread mortality of plants and animals leading to decreases in population densities and changes in species abundances and diversity. Major impact on biological diversity. Ecosystem Wetlands, salt marshes, and mangroves

    29. Hydrocarbons in the Sea (Cont.) • Oil compounds are toxic to marine organisms. • The effect of a spill depends on the habitat. TABLE 12-3 The environmental impact of oil spillage. (2 of 4) Recovery Fast to slow: Dependent on current flow, shoreline, characteristics, and community stability. Initial impact Moderate to heavy: Depends on the season (spawning, migration) and oil’s persistence. Depresses populations and alters the species composition and abundance. Ecosystem Estuaries, bays, and harbors

    30. Hydrocarbons in the Sea (Cont.) • Oil compounds are toxic to marine organisms. • The effect of a spill depends on the habitat. TABLE 12-3 The environmental impact of oil spillage. (3 of 4) Recovery Fast to moderate: Fast recovery for plankton because of rapid times. Moderate recovery rate of benthos, if affected. Initial impact Light to moderate: Impact on plankton light and on fish larvae severe. Moderate impact on the benthos, if oil reaches the sea bottom. Ecosystem Outer continental shelf

    31. Hydrocarbons in the Sea (Cont.) • Oil compounds are toxic to marine organisms. • The effect of a spill depends on the habitat. TABLE 12-3 The environmental impact of oil spillage. (4 of 4) Recovery Fast: Rapid dispersion and degradation of oil. Initial impact Light: Many organisms avoid spill. Impact on plankton is local and depends on chance encounter with spill. Usually water is too deep for significant impact on benthos. Ecosystem Open ocean Source: J. Hyland, Bioscience 26 (1976): 463-506

    32. Hydrocarbons in the Sea (Cont.) • A variety of techniques are used to contain oil spills. • Floating booms • Do NOT work in rough water! • Chemical dispersants • COREXIT • More harm than good? • Burning • Bioremediation

    33. Municipal and Industrial Effluent • Human activity creates an enormous amount of waste each year and much of it ends up in the ocean. Much of this waste includes toxicchemicalsand pathogens(disease-producing organisms).

    34. Municipal and Industrial Effluent(Cont.) • Human wastes fall into 3 major categories: • Sewage • Metals • Artificial biocides Before considering the effects of these materials let’s first look at how they enter the ocean.

    35. Municipal and Industrial Effluent(Cont.) • The human population tends to be concentrated along rivers. As a result rivers contain a large proportion of contaminants and this material is transported to the coastal ocean. • Other material is discharged from underwater pipes.

    36. Municipal and Industrial Effluent (Cont.) • Fate of effluents discharged from a pipe. • The area close to an outfall pipe may consist of few infauna. • With increasing distance from the pipe depleted populations gradually reach normal densities.

    37. Municipal and Industrial Effluent: Sewage • Sewageconsists of a messy sludge, a heterogeneous mixture of organic and inorganic chemicals. • A major component is human wastewhich contains organic matter, inorganic nutrients such as nitrogen and phosphorus, bacteria and viruses.

    38. Municipal and Industrial Effluent: Sewage • Sewage (cont.) • The introduction of nutrients can promote phytoplankton blooms, especially in estuaries. Eventually the bloom dies, sinks and is degraded by bacteria. • The decomposition process uses upoxygen and may cause the water column and sediments to become hypoxic or even anoxic. • This sequence of events is referred to as eutrophication.

    39. Municipal and Industrial Effluent: Sewage • Sewage (cont.) • Fish and invertebrate killsoften occur as a result of eutrophication because they cannot survive without oxygen. • The effects of sewage dumping also extend to the continental shelf where zones of hypoxic bottom water are becoming more and more common. • Chemical poisoning that damages fish (e.g. fin rot) is also evident.

    40. Municipal and Industrial Effluent: Sewage Hypoxic water off Louisiana.

    41. Municipal and Industrial Effluent: Metals • Most metalsoccur naturally in seawater at very low concentrations. • They enter in river water and via volcanic eruptions. • Many organisms require trace amounts of metals for the proper functioning of various physiological processes. • As a result of human activity, many metals enter the ocean, increasing the normal concentrations to such high levels that they become toxic.

    42. Municipal and Industrial Effluent: Metals • Narragansett Bay, RI is an example of a system that • shows heavy contamination due to industrial activity.

    43. Municipal and Industrial Effluent: Metals • Metals (cont.) • Mercury is a by-product of the chlorine-alkali and paper-pulp industries, is released from anti-fouling paints used to paint the hulls of ships, and is an ingredient of pesticides. • Once in the ocean it is adsorbed onto particles and settles out to the sediment. In this form it is very stable and resists biodegradation. For example, large amounts of mercury are used in some gold mining operations to concentrate the precious metal.

    44. Municipal and Industrial Effluent: Metals • Metals (cont.) • Mercury is subject to bioaccumulation by organisms which consume the contaminated particles. • Very high concentrations can build up in the tissues. • Consumption of mercury contaminated shellfish and finfish can lead to neurological damage, kidney malfunction and death in humans. Bioaccumulation: the contaminant is ingested but the organism has no means of getting rid of it, so it accumulates in its tissue - the more it eats, the more poison it has

    45. Municipal and Industrial Effluent: Biocides • Many artificial biocides are manufactured to control the growth of organisms e.g. insect pests. Others have biocidal properties, but they are used in manufacturing. Unfortunately, many of these compounds have entered the sea via run-off and have had devastating effects on sea life. Untreated effluent from a factory

    46. Municipal and Industrial Effluent: Biocides • Several halogenated hydrocarbons or organochlorines, in particular DDT and PCBs are potent biocides. • Unlike other hydrocarbons they are not readily degraded by bacteria. Thus, they persist for a long time in the environment. • Animals which ingest them have difficulty excreting them resulting in bioaccumulation.

    47. Municipal and Industrial Effluent: Biocides • The use of DDT was banned in the United States in the late 1960s, • it is still being manufactured and used in other parts of the world. • It is typically applied by aerial sprayingand much of it ends up being dispersed great distances by winds. • It has been found in deep sea mudsand in the ice of Antarctica. Biomagnification: as Contaminants are passed Up a food chain, the Concentrations increase Or are “magnified”. - upper level carnivores will have the highest concentrations

    48. Municipal and Industrial Effluent: Biocides • Biocides (cont.) • PCBs are used to manufacture plastics, paints, electrical equipment and other products. • They enter the ocean as fine particles following the incineration of discarded products. • Their use was banned in the United States in 1979. • Nevertheless, they are widespread in the oceans because they are not easily degraded.

    49. Municipal and Industrial Effluent: Biocides • Both DDT and PCBs accumulate in the fatty deposits of organisms. • Their concentrations in organisms are biomagnified.

    50. Municipal and Industrial Effluent: Biocides • Biocides (cont.) • Toxic effects of DDT and PCBs include: • The incomplete development of copepods and oysters. • The death of shrimp and a variety of fish. • The death of fish-eating birds.