Limitations of sediment quality surveys: A case study of an urban watershed in British Columbia, Canada

This case study of a 7200 ha, urban watershed illustrates the challenges in volved in using sediment quality surveys to determine pollutant sources and trends. Trace metal and chlorinated hydrocarbon analyses were performed on sediment samples obtained from 33 stream, 24 street, and 1 lake (sediment core) locations. The stream and street sediment survey was initially conduc ted in 1973 and repeated in 1993. Consistent results across all sediment me dia indicate significant reductions in Pb, PCB, and DDT levels have occurre d since the 1970's as a result of source controls. While streambed results indicate Hg and Mn levels have increased significantly since 1973, neither a spatial analysis of streambed results or a comparison to street concentra tions indicate a source for the increase. A more detailed gee-chemical anal ysis and/or atmospheric contaminant survey may provide more conclusive sour ce information. (C) 1998 IAWQ Published by Elsevier Science Ltd. All rights reserved.