This topic contains a solution. Click here to go to the answer

Author Question: Why are plastics a more serious threat than oil spills, and how are they harmful to marine mammals ... (Read 40 times)

Mr. Wonderful

  • Hero Member
  • *****
  • Posts: 866
Why are plastics a more serious threat than oil spills, and how are they harmful to marine mammals and seabirds?

Question 2

If the levels of synthetic organic chemicals are very low in seawater, then how is chlorinated hydrocarbons found in dolphins at dangerous levels?



Related Topics

Need homework help now?

Ask unlimited questions for free

Ask a Question
Marked as best answer by a Subject Expert

katara

  • Sr. Member
  • ****
  • Posts: 305
Answer to Question 1

Although we typically think of pollutants as something that enters the ocean in a dissolved state, much of the burden can also arrive in solid form. About 275 million metric tons of plastic produced each year, and approximately 8 million metric tons ends up in the ocean. While oil spills get more attention as a potential environmental threat, plastic is far more serious danger. Oil is harmful but, unlike plastic, it eventually biodegrades. Scientists estimate that some kinds of synthetic materials-plastic six-pack holders, for example-will not decompose for about 400 years.


Hundreds of marine mammals and thousands of seabirds die each year after ingesting or being caught in plastic debris. Sea turtles mistake plastic bags for their jellyfish prey and die of intestinal blockages. Seals and sea lions starve after becoming entangled in nets or muzzled by six-pack rings. The same kinds of rings strangle fish and seabirds. About a quarter of a million Laysan albatross chicks die each year when their parents feed them bits of plastic instead of food.

Answer to Question 2

The level of synthetic organic chemicals in seawater is usually very low, but some organisms at higher levels in the food chain can concentrate these toxic substances in their flesh. This biomagnification is especially hazardous to top carnivores in a food web. Biologists have discovered that some nearshore dolphins off U.S. coasts are intensely contaminated. Past studies have found concentration of chlorinated hydrocarbons in these animals as high as 6,900 parts per million (ppm), which is high enough to disrupt the dolphins' immune systems, hormone production, reproductive success, neural function, and ability to stave off cancers. These levels vastly exceed the 50 ppm limit the U.S. government considers hazardous for animals, and 5 ppm considered the maximum acceptable for humans




katara

  • Sr. Member
  • ****
  • Posts: 305

 

Did you know?

The average adult has about 21 square feet of skin.

Did you know?

According to the CDC, approximately 31.7% of the U.S. population has high low-density lipoprotein (LDL) or "bad cholesterol" levels.

Did you know?

Though methadone is often used to treat dependency on other opioids, the drug itself can be abused. Crushing or snorting methadone can achieve the opiate "rush" desired by addicts. Improper use such as these can lead to a dangerous dependency on methadone. This drug now accounts for nearly one-third of opioid-related deaths.

Did you know?

Elderly adults are living longer, and causes of death are shifting. At the same time, autopsy rates are at or near their lowest in history.

Did you know?

In 2010, opiate painkllers, such as morphine, OxyContin®, and Vicodin®, were tied to almost 60% of drug overdose deaths.

For a complete list of videos, visit our video library