11.3 What marine environmental problems are associated with non-petroleum chemical pollution?

There are many other types of pollution besides petroleum that are considered types of marine chemical pollution i.e. sewage sludge, DDT, PCBs, mercury, and even chemicals contained in prescription and non-prescription drugs

Sewage Sludge

Sewage treated at a facility typically undergoes primary treatment where solids are allowed to settle and separate from liquid, and secondary treatment, where it’s exposed to bacteria-killing chlorine.

  • sewage sludge = semisolid material that remains after the treatments, contains a toxic brew of:

    • human waste

    • oil

    • zinc

    • copper

    • lead

    • silver

    • mercury

    • pesticides

although clean water act of 1972 prohibited the dumping of sewage into the ocean after 1981, the high cost of treating and disposing of sewage sludge on land resulted in extension waivers being granted to many municipalities

  • summer of 1988: non-biodegradable debris including medical waster washed up on atlantic coast beaches and adversely affected tourist business

NY’s Sewage Sludge Disposal at Sea

  • sewage sludge from NY and Philly normally transported offshore by barge and dumped in the ocean at sites

  • both sites are shallow —> water column is relatively uniform —> even smallest sludge particles reach bottom w/out undergoing much horizontal transport —> ecology of dump site severely affected

    • large conc. of organic and inorganic matter seriously disrupts chemical cycling of nutrients —>greatly reduced species diversity —> sometimes overabundance of algae that causes dissolved oxygen to be reduced to very low levels

  • 1986: shallow-water sites abandoned, sewage transported to a deep-water site beyond the cont. shelf break, so usually well-developed density gradient and internal waves moving along density gradient can horizontally transport particles at rates 100times faster than they sinl

    • local fisherman reported adverse effects on fisheries after deep-water dumping began —. project terminated 1993 —> municipalities must dispose of sewage on land

Boston Harbor Sewage Project

prior to 1980s, 48 diff communities in boston used an antiquated sewage system to dump sludge and partially treated sewage at the entrance to boston harbor

  • tidal currents often swept the sewage back into the bay OR system became overloaded and dumped raw sewage directly into the bay, making Boston Harbor one of the most polluted bays in US

  • court-ordered cleanup of boston harbor in 1980s —> construction of new waste treatment facility at deer island

DDT and PCBs

DDT = pesticide ; PCBs = industrial chemicals

  • both persistent, biologically active chemicals that have been introduced into the oceans entirely as a result of human activities

  • bc of toxicity, persistence, and propensity for accumulating in food chains —> classified as persistent organic pollutants(POPs) capable of causing cancer, birth defects, etc.

DDT was widely used in agriculture during 1950s and improved crop productino throughout developing countries BUT extreme effectiveness as an insecticide and persistence as a toxin in the environment —> host of environmental problems i.e. devastating effects on marine food chains

PCBs = industrial chemicals once widely used as liquid coolants and insulation in industrial equipment i.e. power transformers, where they were released into the environment

  • widely used in wiring, paints, caulks, hydraulic oils, carbonless copy paper, etc.

  • cause liver cancer, harmful genetic mutations in animals

  • affect animal reproduction —> indicated as causes of spontaneous abortions in sea lions and death of shrimp in Escambia Bay, Florida

DDT and eggshells

  • 1972 - EPA banned use of DDT in US

  • worldwide banned from agricultural use but used in limited quantities for public health purposes —> US continues producing DDT and providing other countries with it

  • danger of DDT first became apparent in marine environment when it affected marine bird populations

    • 1960s - serious decline in brown pelican population of Anacapa Island off S California

    • high conc. of DDT in fish eaten by birds —> produced eggs w/ excessively thin shells bc DDT made it more difficult for calcium to be incorporated into egg shells

    • since DDT was banned, birds came back

  • osprey pop of Long Island Sound declined as well during this time

DDT and PCBs linger in the environment

both enter ocean through atmosphere and river runoff

  • initially concentrated in thin slick of organic chemicals at ocean surface —> sink to the bottom, attached to sinking particles

  • open ocean conc. of DDT and PCBs = 10 and 12 times less than in coastal waters

  • DDT and PCBs are so pervasive that even antarctic marine organisms contain measurable quantities of them

    • bc there hasn’t been agriculture of industry in antarctica to introduce them directly, these chemicals had to have been transported from distant sources by winds and ocean currents

Mercury and Minamata Disease

elemental metal mercury = silvery metal w/ rare property of being liquid at normal room temp, has many industrial uses

Ex. used in manufacture of industrial chemicals and for electrical and electronic applications. in its gaseous form also used in fluorescent lighting so very useful

where does mercury in the ocean come from?

  • some comes from natural sources i.e. volcanic eruptions and leaching from mercury-rich rocks

  • 2/3 comes from human activities:

    • single biggest source is burning of fossil fuels, especially coal which releases mercury into the atmosphere, which then gets washed into the ocean through precipitation and runoff

    • humans also discharge mercury-laden industrial effluent directly into rivers of the ocean

    • improper disposal of mercury batteries

    • mercury levels in ocean increased by 6 times since beginning of industrial revolution

  • large discharges of mercury wouldn’t pose a major threat to human health BUT mercury is converted by bacteria in low-oxygen environments to its toxic form, methylmercury, which diffuses into phytoplankton and then passes up marine food chains in ever-accumulating quantities

    • neurotoxin —> exposure is very bad

Minamata Disease

chemical plant built in 1938 on Minamata Bay, Japan produced acetaldehyde, which requires mercury in its manufacture

  • industrial wastewater that contained methylmercury was discharged into minamata bay —> chemical was ingested and concentrated in tissues of marine organisms including fish and shellfish

  • mercury poisoning now known as Minamata disease became an epidemic in 1956 when plant was only 18 yo

minamata disease = degenerative neurological disorder that affects the human nervous system and causes sensory disturbances including:

  • blindness

  • tremors

  • brain damage

  • birth defects

  • paralysis

  • death

mercury poisoning was the first major human disaster resulting from ocean pollution but japanese gov didn’t declare mercury as the cause of the disease until 1968 —> plant immediately shut down

Bioaccumulation and Biomagnification

during 1960s and 1970s, methylmercury contamination in seafood received a lot of attention; certain marine organisms concentrate within their tissues many substances found in minute concentrations in seawater in a process called bioaccumulation

when animals eat other animals, some of these substances move up food chains and become concentrated in tissues of larger animals = biomagnification

some seafood such as tuna and swordfish contain unusually high amounts of mercury

How much mercury-rich seafood is safe to eat?

3 variables considered to decide safe amount of mercury to eat:

(1) rate at which each group of ppl consumed fish

(2) methylmercury conc. in fish consumed by that people

(3) min. ingestion rate of methylmercury that induces disease symptoms

minimum level of methylmercury consumption that causes poisoning symptoms = 0.3 mg per day

graph shows that higher consumption of fish = greater change of mercury poisoning symptoms

Other types of Chemical Pollutants

  • non-prescription, prescription, and illegal drugs all enter municipal waste treatment systems, which separate solid materials but don’t remove all the dissolved chemicals from processed water —> chemicals make it to the ocean in the remaining liquid-waste stream although normally low in conc.

Ex. hromones from pharmaceuticals for human use and those naturally produced by humans, survive sewage treatment —> discharged into environment eventually making way to ocean

Ex. caffeine - passes through human bodies in urine, bcomes part of waste disposal stream that eventually enters the oceans

  • unknown effect on marine organisms

RECAP

many other types of pollution besides petroleum are considered marine chemical pollutants, including sewage sludge, DDT, PCBs, mercury, and chemicals contained in prescription and non-prescription drugs

CONCEPT CHECK 11.3

(1) how would dumping sewage in deeper water off east coast help reduce negative impacts on the ocean floor?

  • a pycnocline is developed in deeper water - not uniform so it can’t sink all the way to the bottom, damaging organisms. gets carried by an internal current along pycnocline which disperses it and eventually dissolves it

(2) discuss the animal populations that clearly suffered from the effects of DDT and the way in which this negative effect was manifested.

(3) what causes minamata disease? what are the symptoms of the disease in humans?

  • causes = ingestion of methylmercury - normally by eating seafood which has methylmercury in it

  • symptoms = brain damage, tumors, blindness, death, paralysis