Related Experiment Video
Updated: Mar 25, 2026

Laboratory-determined Phosphorus Flux from Lake Sediments as a Measure of Internal Phosphorus Loading
Published on: March 6, 2014
Temporal trends of persistent organic pollutant concentrations in precipitation around the Great Lakes
Marta Venier1, Amina Salamova1, Ronald A Hites1
1School of Public and Environmental Affairsm, Indiana University, Bloomington, IN 47405, USA.
Abstract:
The concentrations of polychlorinated biphenyls (PCBs), polycyclic aromatic hydrocarbons (PAHs), and several chlorinated insecticides in precipitation have been measured in samples collected every month since 1997 at six sites on the shores of the North American Great Lakes. We report here the geometric mean concentrations for each of these compounds for each year and at each site. Assuming a first-order rate decline for these data, we have calculated the time it takes for these concentrations to decrease by half. The halving times are not statistically distinguishable among the sites. Overall, the observed halving times are 11 ± 2 years for the PCBs, 14 ± 3 years for the PAHs, 4.0 ± 0.2 for the hexachlorocyclohexanes, 8.0 ± 0.9 for the DDTs, 5.1 ± 0.8 for the chlordanes, and 8.4 ± 0.6 for the endosulfans. In general, the halving times calculated from precipitation concentrations agree with those calculated from atmospheric vapor and particle phase concentrations.
Related Concept Videos
Gravimetry: Inorganic And Organic Precipitating Agents
Precipitation and Co-precipitation
Freshwater Microbial Ecology
Global Climate Change
Precipitation Titration: Endpoint Detection Methods
In the Volhard method, a standard excess of AgNO3 is first added to the...
Types of Coprecipitation
Sometimes, ions in a crystal lattice can undergo isomorphous replacement by inclusions of similar charge and size. For...

