Identification of landscape and socioeconomic factors contributing to sediment contamination in urban streams and assessment of potential ecotoxicological effects: A case study in metropolitan Kansas City area (Missouri)

Information regarding nonpoint source impact on urban stream sediment quality was still incomplete. This study uses five streams in metropolitan Kansas City area to assess sediment contamination, and to identify contributing landscape and socioeconomic factors. Characterized by similar physical features, heterogeneous urbanization histories, and predominantly residential urban use, these watersheds provided an opportunity to examine a watershed/stream sediment relationship along a continuum of urban development.; Twenty-nine composite sediment samples from approximately 150 depositional zones were analyzed for conventional parameters, polycyclic aromatic hydrocarbons (PAHs), pesticides and their metabolites, and 28-day Hyalella azteca toxicity. Macroinvertebrate community metrics were calculated for fifteen samples. Blockgroup census variables and land use data were examined to determine spatial and temporal variations within the watersheds over the past three decades. Statistical methods were used to identify socioeconomic and landscape factors associated with sediment contaminants.; This study has identified population pressure and residential land use as significant sources of impacts on stream system quality. Both the occurrence and levels of PAHs were associated with current populous residential subwatersheds. PAH levels at individual sites are comparable to those of other urban and heavy industrial areas in North America. While agricultural land use negatively correlates with contaminant levels and stream impairment, economic status and education and other land use categories generally do not show noticeable impact. Organochlorinated pesticides and their metabolites were found restricted in stream sediment where the drainage areas had high population pressure during the 1970s and 1980s, indicative of their exclusive historical urban application. The predominance of isomer p,p'-dichlorodiphenyldichloroethylene (DDE) in dichlorodiphenyltrichloroethane (DDT) compounds reflects long-term weathering processes, confirming their environmental persistence. Measures related to macroinvertebrate community health were generally better in less populous subwatersheds, regardless of urbanization history.; Acid volatile sulfide is found to be a common constituent of local sediments, a factor of consideration when addressing metal toxicity. Amphipod mortality is possibly attributed to sedimentary organic contaminants, rather than metals, aligning with the fact that residential land use dominates the study watersheds. No significant negative impact on stream condition from the Combined Sewer System or Wastewater Treatment Plant has been observed.