『Abstract
Relations between urbanization and particle-associated contaminants
in New England were evaluated using a combination of samples from
sediment cores, streambed sediments, and suspended stream sediments.
Concentrations of PAHs, PCBs, DDT, and seven trace metals (Cd,
Cr, Cu, Hg, Ni, Pb, Zn) were correlated strongly with urbanization,
with the strongest relations to percentage commercial, industrial,
and transportation (CIT) land use. Average PAH and metal concentrations
in the most urbanized watersheds were approximately 30 and 6 times
the reference concentrations, respectively, in remote, undeveloped
watersheds. One-quarter to one--half of sampling sites had concentrations
of PAHs, Cu, Pb, or Zn above the probable effects concentration,
a set of sediment quality guidelines for adverse effects to aquatic
biota, and sediments were predicted to be toxic, on average, when
CIT land use exceeded about 10％. Trends in metals in cores from
urban watersheds were dominantly downward, whereas trends in PAHs
in a suburban watershed were upward. A regional atmospheric-fallout
gradient was indicated by as much as order-of-magnitude-greater
concentrations and accumulation rates of contaminants in cores
from an undeveloped reference lake in Boston compared to those
from remote reference watersheds. Contaminant accumulation rates
in the lakes with urbanization in their watersheds, however, were
1-3 orders of magnitude greater than those of reference lakes,
which indicate the dominance of local sources and fluvial transport
of contaminants to urban lakes. These analyses demonstrate the
magnitude of urban contamination of aquatic systems and air sheds,
and suggests that, despite reductions in contaminant emissions
in urban settings, streams and lakes will decline in quality as
urbanization of their watersheds takes place
Keywords: Sediments; Trace elements; Polycyclic aromatic hydrocarbons;
Urbanization; Paleolimnology; Atmospheric fallout』
1. Introduction
2. Methods
2.1. Sample collection
2.2. Chemical analyses
2.3. Data analysis
2.4. Age dating and sediment focusing in cores
3. Results
3.1. Relations between contaminant occurrence and urbanization
3.2. Trends
3.3. Contaminant mass accumulation rates and fallout fluxes
4. Discussion
4.1. Urban-rural fallout gradient
4.2. The urban land-use gradient
4.3. Effects of urbanization on sediment quality
Acknowledgements
References