Causes ans consequences of increasing demand for abiotic resources of oceans
Minerals - Seafloor Mining
The ocean contains a complex combination of physical, chemical, biological, and geological processes that sometimes result in commercially viable forms of a wide range of minerals. This is particularly true in the deep ocean at areas around hydrothermal vents where hot, chemical-rich fluids pouring up from beneath the seafloor produce potentially valuable deposits. A few efforts to mine deposits on the seafloor have succeeded, but to date, not many have overcome the technical challenges involved in retrieving large amounts of material from the deep ocean.
Cause
Seafloor mining has the potential to help meet demand for many minerals used worldwide and could help bolster the economies of developing nations in one of two ways. The mining could take place in a nation’s own exclusive economic zone, or it could take place on the seafloor under international waters, where the International Seabed Authority dictates that a portion of all mining profits benefit developing nations.
Consequence
However, seafloor mining also has the potential to take a toll on the life in the sea. Anytime the seafloor is disturbed, so too are its fragile ecosystems—though the mining industry maintains that it is using and developing environmentally sensitive techniques, and many ocean habitats often appear to recover from damage. At the same time, the interest in mining is helping scientists study both the oceans’ chemistry and clues about how the planet formed.
Should we be mining the seabed for minerals?
Natural gas and oil
Specialists distinguish different kinds of reservoirs in which large amounts of natural gas or oil have accumulated. Typical reservoir types include:
- ANTICLINE: An anticline is an arching structure of rock layers, a kind of underground hill. It is formed when dense rock layers undergo pressure from the sides caused by movement of the Earth’s crust. When the anticline is composed of impermeable rocks, the rising gas and oil can accumulate there, as in an inverted bowl.
- FLANK OF A SALT STOCK: Salt stocks are large underground accumulations of solid rock salt that can be as much as thousands of metres thick. If an impermeable rock layer (a trap structure) abuts on the flank of a salt stock, then ascending oil and gas will be trapped between the rock layer and the flank, because the salt is also impermeable.
- UNCONFORMITY: An unconformity arises at locations where rock layers abut obliquely, or at an angle to one another. Unconformities are formed by lifting, subsidence, or squeezing of rock packages that are subsequently overlain by younger sediments. If these overlying sediment layers are impermeable, ascending gas and oil can accumulate and concentrate in the underlying rock packages.
- CORAL REEFS:In many instances, natural gas and oil collect in very porous limestone that has formed from ancient coral reefs.
- SALT STOCK OVERHANG: Some salt stocks are mushroom-shaped with a wide dome at the top, which forms a kind of umbrella, known as the overhang. Gas and oil can accumulate beneath this. Salt stock overhangs are mainly the result of immense underground pressure. Salt rises because it is less dense than the overlying strata. It bulges upward into domes or the mushroom-shaped overhangs. These movements are referred to as salt tectonics.
Causes
Throughout the Earth’s history, natural gas and mineral oil have formed from the remains of marine algae and land plants, with large deposits accumulating In certain rock strata. Today, using modern drilling techniques and giant platforms, these resources are being extracted from ever greater depths. Production systems are even being installed on the sea floor.
Source: http://worldoceanreview.com/en/wor-3-overview/oil-and-gas/where-and-how-extraction-proceeds/
Consequences
Offshore drilling operations create various forms of pollution that have considerable negative effects on marine and other wildlife.
These include drilling muds, brine wastes, deck runoff water and flowline and pipeline leaks. Catastrophic spills and blowouts are also a threat from offshore drilling operations. These operations also pose a threat to human health, especially to oil platform workers themselves.
Drilling muds and produced water are disposed of daily by offshore rigs. Offshore rigs can dump tons of drilling fluid, metal cuttings, including toxic metals, such as lead chromium and mercury, as well as carcinogens, such as benzene, into the ocean.
Effects of Drilling Muds
Drilling muds are used for the lubrication and cooling of the drill bit and pipe. The muds also remove the cuttings that come from the bottom of the oil well and help prevent blowouts by acting as a sealant. There are different types of drilling muds used in oil drilling operations, but all release toxic chemicals that can affect marine life. One drilling platform normally drills between seventy and one hundred wells and discharges more than 90,000 metric tons of drilling fluids and metal cuttings into the ocean.
Effects of Produced Water
Produced water is fluid trapped underground and brought up with oil and gas. It makes up about 20 percent of the waste associated with offshore drilling. Produced waters usually have an oil content of 30 to 40 parts per million. As a result, the nearly 2 billion gallons of produced water released into the Cook Inlet in Alaska each year contain about 70,000 gallons of oil.
Effects of Exploration
Factors other than pollutants can affect marine wildlife as well. Exploration for offshore oil involves firing air guns which send a strong shock across the seabed that can decrease fish catch, damage the hearing capacity of various marine species and may lead to marine mammal strandings.
More drilling muds and fluids are discharged into the ocean during exploratory drilling than in developmental drilling because exploratory wells are generally deeper, drilled slower and are larger in diameter. The drilling waste, including metal cuttings, from exploratory drilling are generally dumped in the ocean, rather than being brought back up to the platform.
Effects of Offshore Oil Rigs
Offshore oil rigs may also attract seabirds at night due to their lighting and flaring and because fish aggregate near them. Bird mortality has been associated with physical collisions with the rigs, as well as incineration by the flare and oil from leaks. This process of flaring involves the burning off of fossil fuels which produces black carbon.
Black carbon contributes to climate change as it is a potent warmer both in the atmosphere and when deposited on snow and ice. Drilling activity around oil rigs is suspected of contributing to elevated levels of mercury in Gulf of Mexico fish.
Methane hydrates
When gas molecules are trapped in a lattice of water molecules at temperatures above 0°C and pressures above one atmosphere, they can form a stable solid. These solids are gas hydrates.
Most gas hydrates are formed from methane (CH4). Methane is the simplest hydrocarbon, and is the primary component of the natural gas that we burn for energy. If you hold a hydrate nodule in your hand and light it with a match, it will burn like a lantern wick. There is fire in this ice!
Gas hydrate deposits along ocean margins are estimated to exceed known petroleum reserves by about a factor of three. These hydrate beds leak gases into the water, forming cold seeps on the ocean floor. This hydrocarbon seepage is common on continental margins around the world.
Chemosynthetic communities similar to those found at hydrothermal vents form at cold seeps, using hydrocarbons or hydrogen sulfide for carbon and energy. Seep tube worms, mussels, and clams form two-meter-high bushes over kilometer-sized beds. Most seeps are also characterized by high microbial productivity.
Hydrates influence ocean carbon cycling, global climate change, and coastal sediment stability. Localized meltdowns have caused massive continental slope failure, which can present a geological hazard for shelf oil and gas production. Massive hydrate dissolution events, releasing vast amounts of the greenhouse gas methane, are possible causes of some of the abrupt climate changes seen in the geologic record.
Causes
Methane gas comes from fermenting organic matter and can be distilled from coal and natural gas. As the biomass of dead plants endures the Earth’s heat and pressure, its energy-rich carbon molecules become materials from which methane can be extracted. Methane is the main component of natural gas. Chemistry professor Bassam Shakhashiri of the University of Wisconsin says, “The energy released by the combustion of methane, in the form of natural gas, is used directly” in homes and businesses.
INDUSTRIAL USES
Methane, in the form of natural gas, is used in a variety of industries. It’s a common fabric, plastic, anti-freeze and fertilizer ingredient. Industrial natural gas consumers include companies that make pulp and paper. Food processors, petroleum refineries and companies that work with stone, clay and glass, use the energy it releases. Methane-based combustion helps businesses dry, dehumidify, melt and sanitize their products. The use of methane natural gas in commercial settings also resembles home uses.
HOME USES
Natural gas is cheaper than electricity, according to the Natural Gas Supply Association. They affirm it is the “lowest-cost conventional energy source available for residential use.” Home uses vary. Some consumers use the methane in natural gas as a source of energy while cooking. Others use it to heat and cool their homes.
DISTRIBUTED GENERATION
Through a process called distributed generation, the methane in natural gas can create electricity. Microturbines (heat engines) and natural gas fuel cells can produce enough electrical energy to power a home. While distributed generation technology remains in its infancy, it has a promising future. The Natural Gas Supply Association predicts that distributed generation will offer homeowners energy independence. The first system of this kind was installed in a Latham, New York, home. The home strictly relies on a fuel cell and its natural gas line for its energy needs.
Consequences
Vast amounts of methane hydrate are buried in sediment deposits on the continental slopes. The total global amount of methane carbon bound up in these hydrate deposits is in the order of 1000 to 5000 gigatonnes – i.e. about 100 to 500 times more carbon than is released annually into the atmosphere by the burning of fossil fuels (coal, oil and gas). At low temperatures the methane hydrates on the sea floor are stable, but if the water and the sea floor become warmer, then the hydrates can break down. Because microorganisms then oxidize the resulting methane gas to form the greenhouse gas carbon dioxide (CO2), methane hydrates have recently become a topic of intense discussion within the context of climate change. Methane, which itself acts as a strong greenhouse gas, does not escape directly out of the sea as methane because it is transformed into CO2. But the formation and release of carbon dioxide are considerable. An additional problem is that the oxygen in seawater is consumed through the formation of carbon dioxide.
In 2008 British and German researchers discovered gas seeps at a depth of 350 metres on the continental slope off Spitsbergen that are probably fed by melting hydrates. Long-term measurements of the water temperatures off Spitsbergen indicate that the bottom-water masses and thus also the slope sediments have significantly warmed in recent decades. Models also predict that the sea floor in Arctic areas will continue to heat up in the coming decades and centuries due to climate change. Scientists therefore fear that large quantities of methane hydrate will melt there in the future, releasing increased amounts of CO2 into the ocean and the atmosphere. The oxygen content of the seawater will decrease accordingly.
Furthermore, the CO2 released not only contributes to further global warming, it also leads to acidification of the oceans. Examples from the geological past support this scenario. Based on geological records it can be assumed that hydrates have broken down on a large scale numerous times in the Earth’s history, leading to extreme global warming and massive extinctions of organisms on the sea floor. Further investigations are necessary to determine the scale at which changes in the climate and oceans will accelerate in the future due to the release of methane gas at the sea floor.
Deepwater horizon oil spill
Deepwater Horizon oil spill of 2010, also called Gulf of Mexico oil spill of 2010, largest marine oil spill in history, caused by an April 20, 2010, explosion on the Deepwater Horizon oil rig—located in the Gulf of Mexico, approximately 41 miles (66 km) off the coast of Louisiana—and its subsequent sinking on April 22.
Oil Disaster (Deepwater Horizon): The Rig That Blew Up
Trends in biotic resource use
Source: https://www.sciencenews.org/sites/default/files/2016/09/091716_fish_production-graph_free.png
The viability of alternatives to overfishing
Aquaculture
Aquaculture -- also known as fish or shellfish farming -- refers to the breeding, rearing, and harvesting of plants and animals in all types of water environments including ponds, rivers, lakes, and the ocean. Researchers and aquaculture producers are "farming" all kinds of freshwater and marine species of fish, shellfish, and plants. Aquaculture produces food fish, sport fish, bait fish, ornamental fish, crustaceans, mollusks, algae, sea vegetables, and fish eggs.
Aquaculture includes the production of seafood from hatchery fish and shellfish which are grown to market size in ponds, tanks, cages, or raceways. Stock restoration or "enhancement" is a form of aquaculture in which hatchery fish and shellfish are released into the wild to rebuild wild populations or coastal habitats such as oyster reefs. Aquaculture also includes the production of ornamental fish for the aquarium trade, and growing plant species used in a range of food, pharmaceutical, nutritional, and biotechnology products.
Conservation areas
Marine Conservation Zones are areas that protect a range of nationally important, rare or threatened habitats and species.
There are 50 MCZs in waters around England. These were designated in two phases after a process closely involving stakeholders. The first 27 zones were designated on 21 November 2013. Following consultation, 23 sites in the second phase were announced on 17 January 2016, bringing the total area protected to 7,886 square miles. Updated GIS data for all designated MCZs has been published.
A third phase will be consulted on in 2017, and designated in 2018. The third phase will aim to complete the UK Blue Belt and our contribution to the ecologically coherent network in the North East Atlantic.
Similar schemes are operating in Wales, Scotland and Northern Ireland to contribute to a UK wide network of marine protected areas.
Quotas
For many years, authorities have been attempting to control fishing with a variety of regulatory instruments in order to conserve stocks. These instruments include fishing quotas, limits on the number of fishing days, and restrictions on the engine power of fishing vessels. However, many of these measures fail because the quotas and restrictions introduced are not stringent enough, are not properly monitored, or because fishing practice simply ignores the regulations.
Overfishing means that the annual catch volumes are ecologically and economically unsustainable. Ultimately, excessively high catches are the result of too much fishing effort. As fish stocks decline, the effort required to catch a given quantity of fish continually increases. Fisheries policy or centralized fisheries management has responded to this situation by adopting direct measures that aim to limit catch volumes or indirect measures focussing on fishing effort.
Reducing catches
In order to reduce total catch to a biologically and economically sustainable level, authorities frequently introduce Total Allowable Catches (TACs). Ideally, the TACs should be set at a level that allows the maximum economic yield (MEY) to be achieved in the long term. However, TACs alone are not enough to safeguard economic efficiency, for at the start of every new fishing season with a limited TAC, each fisherman would attempt to secure the largest possible share of the quota for himself by engaging in a very high fishing effort for a short period (also known as the “race to fish”). If the quota is thus exhausted within a relatively short time, fishing capacity then remains unused until the next fishing season. In order to give the individual fishermen a modicum of planning security throughout the entire fishing season, the TACs are therefore allocated to individual vessels, fishermen or cooperatives.
Managing ocean pollution
Regulating ocean dumping
What was dumped into the ocean before 1972?
In the past, communities around the world used the ocean for waste disposal, including the disposal of chemical and industrial wastes, radioactive wastes, trash, munitions, sewage sludge, and contaminated dredged material. Little attention was given to the negative impacts of waste disposal on the marine environment. Even less attention was focused on opportunities to recycle or reuse such materials. Wastes were frequently dumped in coastal and ocean waters based on the assumption that marine waters had an unlimited capacity to mix and disperse wastes.
Although no complete records exist of the volumes and types of materials disposed in ocean waters in the United States prior to 1972, several reports indicate a vast magnitude of historic ocean dumping:
In 1968, the National Academy of Sciences estimated annual volumes of ocean dumping by vessel or pipes:
- 100 million tons of petroleum products;
- two to four million tons of acid chemical wastes from pulp mills;
- more than one million tons of heavy metals in industrial wastes; and
- more than 100,000 tons of organic chemical wastes.
A 1970 Report to the President from the Council on Environmental Quality on ocean dumping described that in 1968 the following were dumped in the ocean in the United States:
- 38 million tons of dredged material (34 percent of which was polluted),
- 4.5 million tons of industrial wastes,
- 4.5 million tons of sewage sludge (significantly contaminated with heavy metals), and
- 0.5 million tons of construction and demolition debris.
EPA records indicate that more than 55,000 containers of radioactive wastes were dumped at three ocean sites in the Pacific Ocean between 1946 and 1970. Almost 34,000 containers of radioactive wastes were dumped at three ocean sites off the East Coast of the United States from 1951 to 1962.
Following decades of uncontrolled dumping, some areas of the ocean became demonstrably contaminated with high concentrations of harmful pollutants including heavy metals, inorganic nutrients, and chlorinated petrochemicals. The uncontrolled ocean dumping caused severe depletion of oxygen levels in some ocean waters. In the New York Bight (ocean waters off the mouth of the Hudson River), where New York City dumped sewage sludge and other materials, oxygen concentrations in waters near the seafloor declined significantly between 1949 and 1969.
Why is regulating ocean dumping important? How does EPA help protect the ocean?
Unregulated disposal of wastes and other materials into the ocean degrades marine and natural resources and poses human health risks. For nearly 45 years, EPA’s Ocean Dumping Management Program has stopped many harmful materials from being ocean dumped, worked to limit ocean dumping generally, and worked to prevent adverse impacts to human health, the marine environment, and other legitimate uses of the ocean (e.g., navigation, fishing) from pollution caused by ocean dumping.
What materials are dumped into the ocean today?
Today, the vast majority of material disposed in the ocean is uncontaminated sediment (dredged material) removed from our nation’s waterways to support a network of coastal ports and harbors for commercial, transportation, national defense and recreational purposes. Other materials disposed in the ocean include human remains for burial at sea, vessels, man-made ice piers in Antarctica, and fish wastes.
Source: https://www.epa.gov/ocean-dumping/learn-about-ocean-dumping
Great Pacific Garbage Patch (GPGP)
The Great Pacific Garbage Patch is a collection of marine debris in the North Pacific Ocean. Marine debris is litter that ends up in oceans, seas, and other large bodies of water.
The Great Pacific Garbage Patch, also known as the Pacific trash vortex, spans waters from the West Coast of North America to Japan. The patch is actually comprised of the Western Garbage Patch, located near Japan, and the Eastern Garbage Patch, located between the U.S. states of Hawaii and California.
These areas of spinning debris are linked together by the North Pacific Subtropical Convergence Zone, located a few hundred kilometers north of Hawaii. This convergence zone is where warm water from the South Pacific meets up with cooler water from the Arctic. The zone acts like a highway that moves debris from one patch to another.
The amount of debris in the Great Pacific Garbage Patch accumulates because much of it is not biodegradable. Many plastics, for instance, do not wear down; they simply break into tinier and tinier pieces.
The seafloor beneath the Great Pacific Garbage Patch may also be an underwater trash heap. Oceanographers and ecologists recently discovered that about 70% of marine debris actually sinks to the bottom of the ocean.
The strategic value of oceans - South China Sea
Territorial spats over the waters and islands of the South China Sea have roiled relations between China and countries like Philippines, Vietnam, Taiwan, Malaysia, and Brunei in recent years, and tensions continue to escalate in the wake of U.S. President Barack Obama’s announced “pivot” of focus to the region. A handful of islands comprise the epicenter of the territorial dispute, making up an area known as the “cow’s tongue” that spans roughly the entire South China Sea. The region is home to a wealth of natural resources, fisheries, trade routes, and military bases, all of which are at stake in the increasingly frequent diplomatic standoffs. China’s blanket claims to sovereignty across the region and its strong resistance to handling disputes in an international arena have mired attempts at resolving the crises and intensified nationalist postures in all countries involved, particularly Vietnam and the Philippines. Experts say the potential for an escalated conflict in the South China Sea—while seemingly distant for now—presents an ongoing crisis for the region, as well as for U.S. interests in the area.
Source and more at: https://www.cfr.org/backgrounder/south-china-sea-tensions
Synthesis and evaluation
Use the content from this post to answer the following exam style question: ‘Explain how ocean exploitation and management take place at varying scales’. 10 marks
Extra - microplastics
Why there are plastics in Pacific Northwest shellfish
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