Chem 1103: Lecture 14: The Ocean’s Resources: Chap. 14 & The Human Presence in the Ocean: Chap. 15
· This is the economics and policy part
· Law of the sea
o Several treaties regarding ownership and exploitation of the marine resources have been ratified in the last 50 years
§ President Truman extended U.S. control of the marine resources from the shoreline to a depth of 100 fathoms (183 m)
§ The 1958 and 1960 Geneva Conventions on the Law of the Sea resulted in a treaty that place the control of the sea bed, sea bed resources, and water of the continental shelf under the country that owns the nearest land
§ The 1982 United Nations’ Draft Convention on the Law of the Sea established:
· Territorial waters that extend seaward for 12 nautical miles from the coast and are under the direct jurisdiction of the coastal nation
· An exclusive economic zone (EEZ) that extends for 200 nautical miles offshore or to the edge of the continental shelf, if that is farther, giving coastal nations the right to regulate fishing, mineral resources, pollution, and research
· The right of vessels to free and innocent passage outside of the territorial waters and through international straits that lie within territorial waters
· That all private exploitation of mineral resources beyond the exclusive economic zones must be approved by the United Nations’ International Seabed Authority and that part of the revenue from the resources will be shared with the developing nations
§ Exclusive economic zones contain about 40% of the ocean and the high seas represent the remaining 60%
· The U.S. has the world’s largest EEZ because of the large areas surrounding various island possessions and states
· The U.S.’s EEZ is 30% larger than the land area of the U.S.
· Mineral Resources
o Petroleum is a complex mixture of hydrocarbons, combinations of hydrogen and carbon with various amounts of nitrogen and metals
§ Oil as it comes from the ground is called crude oil or petroleum
· The composition of the petroleum varies greatly depending upon the geologic history of the material
· The smaller the size of the hydrocarbon molecule, the lighter (less dense) the oil it is
· Oil can be separated into various densities by distillation because oils of different densities evaporate at different temperatures
o Petroleum, oil, and gas are hydrocarbons derived from sedimentary rocks which were deposited in quiet, productive regions with anoxic bottom waters in which the remains of phytoplankton accumulated
§ Deep burial resulting in high temperature and pressure converted the organic remains into hydrocarbons
· Initially oil, but at higher temperatures and pressures, methane (CH4) natural gas was generated
§ Pressure forced the oil and gas from the source rock into water-filled porous and permeable strata above
§ Because oil and gas are less dense than water, they migrated upwards until their path was blocked by an impermeable layer
§ Oil and gas accumulated, forming a large deposit within the pores of the rock, usually sandstone
§ Location of possible accumulations of oil and gas can be determined using seismic reflection and refraction methods to determine the configuration of rock layers
· These methods only indicate if the configurations of rock layers have the potential to trap oil and gas. They do not indicate if oil and gas are present
§ Large reserves in ANWR and Mars (Gulf of Mexico), but only a fraction of what America consumes
o Gas Hydrates refer to the unusual hydrocarbon deposits that consist of frozen water molecules entrapping a single molecule of methane (natural gas)
§ Gas hydrates occur in polar sediments and in deposits of the continental slope between the depths of 300 and 500 m where cold water is in contact with the sea floor
§ These deposits contain incredibly large amounts of gas, but currently there is no economical method for its recovery
§ Deposits on continental shelf of North Carolina are enormous, roughly 350x annual US energy consumption (annual ~ 6.6 billions gallons/yr)
o Sand and gravel are natural aggregates of unconsolidated sediment with grain size greater than 0.0625 mm in diameter
§ Sand and gravel accumulate in high energy environments where strong currents and/or waves currently prevail and occur as relict sediments across the continental shelf from when sea level was lower
§ These materials are used for construction of roads an buildings and to replenish beaches which are undergoing erosion
§ Mining sand and gravel deposits from the shelf threatens both the benthic and pelagic communities and introduces large amounts of material into suspension
§ Presently only 1% of sand and grave come from offshore
o Manganese nodules are composed of about 20-30% manganese, 10-20 % iron oxide, 1.5% nickel, and less than 1 % copper, cobalt, zinc, and lead
§ Locally the nodules can be very abundant, as on the subtropical sea floor of the Pacific Ocean, where billions of kilograms occur
§ Currently, there is no economical method of recovering the nodules from the deep sea
o The sides of many seamounts and islands are enriched in cobalt between the depths of 1 and 2.5 km
§ Cobalt is a strategic metal used in making jet engines, and the U.S. cannot produce sufficient cobalt to meet its needs
o Phosphorus is required for growth by all organisms
§ Phosphate deposits generally form on submarine terraces where coastal upwelling generates high productivity
§ Organic wastes and remains accumulate in the sediment and as they decay they release phosphorus compounds which precipitate as phosphate nodules
§ Nodules grow at the rate of about 1-10 mm /1000 yr
§ World consumption of phosphate is about 150 million tons per year and known supplies should last until 2050
· Living Resources
o Marine finfish can be divided into the pelagic fish which live in the water column and the groundfish which live on the sea floor
§ Most of the ocean is sparsely populated because of low nutrient availability
§ Areas of major fish production are the coastal waters and regions of upwelling
§ Because they are economic to capture, major commercial fishes are those which form large schools
§ The fishing industry uses sonar, scouting vessels, airplanes, and satellites to locate schools and then deploy the fishing fleets to those areas
§ Drift nets are controversial because they capture everything too large to pass through the mesh of the net and needlessly kill many organisms
· The 1989 United Nations’ Convention for the Prohibition of Long Drift Nets prohibited drift nets longer than 2.5 km, but compliance is largely voluntary and impossible to enforce on the open sea
§ World ocean fish production appears to have leveled at between 80 and 90 million tons annually
§ Currently the expense incurred in fishing exceeds the profit from the sale of the fish and fishing industries only survive through government subsidy
o Overfishing is removing a living resource form the sea faster than it can replace itself, and if continued sufficiently long, the resource will collapse
§ 69% of fisheries are overfished
§ Overfishing is possible today because:
· Technology has made it easier to locate large schools of fish and direct fishing fleets to those locations
· Mismanagement of policies related to sustaining fish populations
· Fishermen resist quotas and misreport catches
§ Maximum sustainable yield is the theoretical maximum amount of fish that can be removed form a population without significantly interfering with the population’s ability to renew itself
· The maximum sustainable yield is based upon biological factors such as population dynamics, food webs and spawning success, and the fishing effort required to produce a given catch
· Problems with determining a maximum sustainable yield include:
o Under-reporting the amount of fish caught
o Natural fluctuations of populations due to predation and food supply
o The inherent difficulty in determining the size of fish populations
o The unknown impact of discard fish (those returned to the sea because they are too small or of poor quality) on the population
· Politics frequently result in altering the scientifically determined maximum sustainable yields to meet a political end
§ It has been suggested that the concept of the maximum sustainable yield be replace by the “precautionary principle” which is to avoid anything that may damage or negatively impact a fishery
o Mariculture is marine agriculture or fish farming of finfish, shell fish, and algae
§ Mariculture requires raising the organisms under favorable conditions until they are large enough to be harvested for food
§ Currently ,about one out of every four fish consumed spent part of its life in mariculture and for some organisms the percentage supplied by mariculture is even larger
§ For mariculture to be economically viable, the species must be:
· Marketable
· Inexpensive to grow
· Trophically efficient
· At marketable size within 1 to 2 years
· Disease resistant
· Mussels, oyster, salmon
BREAK
· Pollution: What is it
o Pollution is the introduction by man, directly or indirectly, of substances or energy into the environment, resulting in deleterious effects such as harm to living resources, hazards to human health, hindrance of marine activities, including fishing, impairing quality for use of sea water, an reduction of amenities
§ In studying pollution it is important to have a baseline from which to measure man’s impact upon the environment because some of what is considered to be pollution may be occurring naturally and not caused by man
§ Pollution tends to be concentrated in three parts of the ocean environment:
· Sea floor - accumulation on the bottom either by the settling out of particles or being chemically attached to sediment
o This mainly affects the benthos
· Pycnocline – some pollution accumulates along the pycnocline because it is too light to sink through the dense bottom water
o This is very common in estuaries
· Neuston layer – accumulation of pollution on the air-water interface
o This mainly affects the plankton
§ Pollutants are eventually broken down by various oceanographic and biological processes
· Hydrocarbons in the Sea
o Only a small fraction of the oil in the sea comes from major oil tanker accidents
§ About 32% if the oil in the sea comes from contaminated rivers
§ Another 32% of the oil is released by tankers as they pump out their bilges and from the incomplete burning of fuel in their engines and general shipping traffic
§ 13% of the oil enters the sea as leakage from coastal refineries
§ 21% of the oil is from natural oil seeps, atmospheric fallout
o Once in the environment, an oil spill begins to be altered
§ The oil slick naturally spreads outward and is additionally distributed by waves and currents
· This greatly increases the surface area of the spill
§ The light fraction of the oil evaporates, the soluble portion dissolves into the water and the heavy insoluble fraction emulsifies (mixing of one fluid into another without dissolving) and is vertically mixed in the water column
· Emulsified oil forms globules which eventually become floating tar balls that finally sink to the bottom or wash ashore where they weather or are buried
§ Microbes begin to degrade the petroleum into CO2
§ Larger organisms ingest and metabolize some of the oil
o The rate at which the oil is dispersed and dissipated depends upon the weather, composition of the crude, and the waves and currents
o All oil is toxic at all levels of the food chain, but the degree of damage depends upon the type of petroleum and upon the specific habitat and ecosystem
§ In a coastal environment, an oil spill kills benthic, pelagic, and nektonic organisms by poisoning or smothering
§ On a muddy intertidal flat a spill will decimate the benthos, both plants and animal
§ On the open sea a spill does less damage because the volume of water into which it mixes is much greater and the bottom is so deep it may be unaffected
o There are several methods employed in attempting to clean a spill
§ Floating booms are barriers placed around the spill to try and prevent it from dispersing so that it can be removed more easily
· This is not effective if waves are large or winds and currents are strong
§ Chemical dispersants disperse the oil into the water
· Dispersants do not actually remove the oil and frequently are as damaging or even more damaging to the environment than the oil
§ Burning the oil at the surface
· Oil is difficult to ignite and to keep burning. Additionally this method creates air pollution which later settles onto the sea
§ Skimming involves removing the surface water and recovering the oil
§ Bioremediation involves stimulating the growth of microbes that feed on the oil so that they decompose it
§ If oil reaches the shore, it should be removed without disturbing the substrate
· Municipal and Industrial Effluents
o Each year humans produce over 20 billion tons of wastes, much of which is disposed of in the ocean
§ Most of the wastes come from farmland, cities, and industrial areas and enter the sea by way of rivers
§ Wastes tend to be concentrated in harbors, bays, and estuaries
§ All bodies of water have a natural capacity to clean themselves of a certain amount of pollution, but dense populations can produce so much pollution that the self-cleaning capacity is exceeded
§ As pollution enters the sea, it can be greatly diluted depending upon the waves and currents
§ Various pollutants behave differently depending upon their temperature, density, and solubility
§ As effluents are released, they form a contaminant plume which increases in size with distance as the pollutant is diluted by surrounding water
· Particulate matter will settle out at greater distances form the source as particle size decreases
· Some of the material will be concentrated on the pycnocline