14-7 Ocean water pollution
“oceans are the ultimate sink for much of our waste”
oceans dilute a lot of pollution, and some forms of marine life may be “more resilient” to pollution than previously thought
coastal areas “bear the brunt” of ocean pollution
40% of world’s population lives within 100 km (60 miles) of a coast, so there are a lot of people in this area
world’s 15 largest metro areas (each > 10,000,000) are on coasts
coastal areas growing fast
Municipal sewage & waste, sometimes untreated
Runoff of fertilizer, etc
Deposition from atmosphere
These all bring in nutrients that promote “explosive” algae growth that is ultimately harmful to fish, seafood, birds.
Good example of this is , depleted oxygen zone that forms every year off the mouth of Mississippi R., fed by a huge drainage basin in middle of U.S.
Miller cites big problems in Chesapeake Bay , where there is much pollution due to large population, but only 1% of waste entering the Bay actually gets “flushed” into the ocean.
However, an integrated coastal mgmt program has started to achieve “impressive” results, reducing nitrogen and phosphate
US has stopped dumping industrial waste offshore, but many countries still do it.
But we still dump “dredge spoils” …these are sediments dredged from bottoms of rivers and harbors to maintain shipping channels….Maintenance of shipping channels is a major task of the US Army Corps of Engineers
Other countries also dump sewage sludge (waste material that is removed from wastewater at sewage treatment plants), but US stopped doing this in 1992.
The most dramatic incidents (tanker spills and well blowouts) are not necessarily the most damaging…..Miller cites releases during normal oil well operations, pipeline leaks, and washing of oil tankers as more important.
Other sources are natural, such as seeps.