11:32 am - Monday May 28, 2012

Marine Pollution

Marine pollution occurs when harmful, or potentially harmful effects, can result from the entry into the ocean of chemicals, particles, industrial, agricultural and residential waste, noise, or the spread of invasive organisms. Most sources of marine pollution are land based. The pollution often comes from nonpoint sources such as agricultural runoff and wind blown debris.

Many potentially toxic chemicals adhere to tiny particles which are then taken up by plankton and benthos animals, most of which are either deposit or filter feeders. In this way, the toxins are concentrated upward within ocean food chains. Many particles combine chemically in a manner highly depletive of oxygen, causing estuaries to become anoxic.

When pesticides are incorporated into the marine ecosystem, they quickly become absorbed into marine food webs. Once in the food webs, these pesticides can cause mutations, as well as diseases, which can be harmful to humans as well as the entire food web.

Toxic metals can also be introduced into marine food webs. These can cause a change to tissue matter, biochemistry, behaviour, reproduction, and suppress growth in marine life. Also, many animal feeds have a high fish meal or fish hydrolysate content. In this way, marine toxins can be transferred to land animals, and appear later in meat and dairy products.

Causes of Marine Pollution

The main cause of any type of pollution is humans. Our activities and carelessness is what produces the pollution that litters our oceans. Some of the major causes of ocean pollution are things such as oil spills, dumping toxic industrial waste, incorrect disposal of garbage, waste water and sewage, run off from agricultural endeavors and ocean mining. Each of these activities causes the oceans to become polluted.

Oil spills occur when crude oil is transported across the ocean to refineries or directly for ocean oil stations. In some cases the oil spill is accidental, but sometimes the ship or station needs to dump some of the waste oil. Statistics show that 45 percent of ocean water pollution is caused by marine transportation, while 32 percent is caused by loading, discharging, and flushing of oil tankers.

The dumping of toxic industrial waste into the ocean is common practice in many countries around the world. Many major industrial companies have outlets that run directly into the ocean. There has even been nuclear waste dumped into the oceans as a way of getting rid of it.

Waste water, sewage and water runoff are also major cause of ocean pollution. Many countries treat and then dump their sewage into the ocean rationalizing that the treatment of the sewage makes it a safe thing to do. Power plants often direct their waste water into the ocean. This water is often full of heavy metals. Runoff from farms can also cause problems in the ocean. Mush of the runoff includes pesticides and herbicides that can cause the death of some marine species and the overgrowth of other aquatic plant species such as blue green algae.

Effects of Marine Pollution

1) Untreated or partially treated sewage effluent, or organically rich industrial effluent such as that from fish processing plants, present a number of problems.

  • Decomposition of organic matter causes a drop in dissolved oxygen, particularly in calm weather and sheltered bays. This can cause the death of marine plants and animals, and may lead to changes in biodiversity (see Enviro Facts “Biodiversity”).
  • Effluent, rich in nitrogen and phosphorus, results in `eutrophication’ (overfertilization), which may cause algal blooms. These blooms can discolour the water, clog fish gills, or even be toxic, e.g. red tides. Microbial breakdown of dead algae can cause oxygen deficiencies.
  • Pathogenic microorganisms cause gastric and ear-nose- throat infections, hepatitis, and even cholera and typhoid. Filter feeding animals (e.g. mussels, clams, oysters) concentrate pathogens in their gut, so eating shellfish from polluted waters is a health risk.
  • Effects from industrial discharges in South Africa are generally limited to the area next to the discharge (the `mixing zone’). Water quality guidelines specify maximum levels of pollutants allowed in the receiving water.

2) Oil spills smother plants and animals, preventing respiration. In seabirds and mammals it can cause a breakdown in their thermal insulation. Chemical toxicity can cause behavioral changes, physiological damage, or impair reproduction. Oil pollution is an eyesore, and cleanup and subsequent disposal of oily wastes is difficult.

3) Pesticides, such as DDT, and other persistent chemicals e.g. PCBs, accumulate in the fatty tissue of animals. These chemicals can cause reproductive failure in marine mammals and birds.

4) Ships often paint their hulls with anti-fouling substances, e.g. tributyl-tin or TBT, to prevent growth of marine organisms. These substances leach into water and, in high traffic areas such as harbours and marinas, can affect animal life. There is a world wide trend towards limiting the use of TBT containing paints.

5) Plastics kill many marine animals. Turtles, for example, often swallow floating plastic bags, mistaking them for jelly- fish. Animals are often strangled when they become entangled with plastic debris.

Solution of Marine Pollution

Some quick fix tips to reduce pollution:
1. Keep a few disposable oil absorbent pillows on hand to sop up oil spillage from bilges.
2. Use absorbent pads to catch spills from oil changes or minor bilge spills.
3. Clean up spilled oil or diesel before you use bilge cleaner. A gallon of bilge cleaner and water mixed with a quart of oil produces 5 quarts of hazardous waste. It’s better to get the spill up first, then use bilge cleaner or detergent to clean up the residue.
4. If you have an oil or diesel leak, fix it. Or, if it’s one you can’t stop completely, use absorber pillows, tied securely so as not to foul your bilge pumps. Don’t let oily waste be pumped overboard.
5. Dispose of hazardous waste in approved dumps. If you don’t know what to do with your oily waste, contact the marina office for help.
6. Never flush toilets or waste overboard in prohibited areas. Almost all regulations now require waste be held in approved holding tanks until it can be removed at dockside sanitary pump-out facilities. Some regulations no longer allow overboard discharge even outside the three-mile coastal limit. Check before you discharge. If in doubt, use shore pump-out!
7. Porta-Potties can’t be dumped overboard either. They must be brought to a discharge area for release of their contents. Most public rest rooms will not allow them to be drained there, so you can use marina facilities, your toilet when you return home, or an RV facility.

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