Estuaries awash in contaminants.Estuaries awash in contaminants
Oceanographers have long realized that nutrients and pollutants from land sources travel downriver down·riv·er
adv. & adj.
Toward or near the mouth of a river; in the direction of the current: swam downriver; a downriver canoe race.
Adv. 1. and collect in the waters of estuaries -- the ecologically critical zone where river meets ocean. But new research suggests pollutants from the ocean also concentrate in estuaries -- a finding that helps explain coastal pollution and may have implications for dumping practices in the ocean, says Curtis R. Olsen, a researcher at the Oak Ridge (Tenn.) National Laboratory who has studied the Savannah River estuary on the Georgia-South Carolina border with colleagues from Oak Ridge and the Skidaway Institute of Oceanography After the American Civil War (1861-1865), many of the plantations on the island were unable to continue without slave labor, and their owners gradually sold them to wealthy northerners, who mostly held them on speculation. in Savannah Savannah, city, United States
Savannah, city (1990 pop. 137,560), seat of Chatham co., SE Ga., a port of entry on the Savannah River near its mouth; inc. 1789. .
The researchers measured the estuarian concentration of several different isotopes of plutonium Plutonium (Pu) has no stable isotopes. A standard atomic mass cannot be given. Decay modes
Twenty plutonium radioisotopes have been characterized. The most stable are Pu-244, with a half-life of 80. (Pu), which binds to small particles in the water. One isotope, Pu-238, is released upriver in minuscule amounts by the Department of Energy's Savannah River Plant, a nuclear facility. On the other hand, Pu-239 and Pu-240 are fallout from above-ground testing of nuclear weapons and therefore come predominantly from the ocean. When they measured the concentration of the three isotopes, the researchers found the estuaries enriched in the oceanic plutonium -- meaning particles in the ocean must gradually migrate landward land·ward
adv. & adj.
To or toward land: sailing landward; the landward side of a coastal fortification.
land and concentrate whatever pollutants they carry within the estuaries, says Olsen. While people who study ocean sediments have known of such landward motion, he says, those who study contaminants in estuaries have not considered this process before.
This finding is not limited to plutonium, Olsen says, because particles also can bind and carry other pollutants such as heavy metals, the insecticide DDT DDT or 2,2-bis(p-chlorophenyl)-1,1,1,-trichloroethane, chlorinated hydrocarbon compound used as an insecticide. First introduced during the 1940s, it killed insects that spread disease and feed on crops. and PCBs (polychlorinated biphenyls). As well, he adds, this transportation process may carry contaminants landward into such coastal environments as bays and fjords.