Institute of Ecosystem Studies

2007 BES Annual Meeting Presentation and Poster Abstracts

Particulate Organic Matter in Urban Streams: TSS and FPOM Concentrations and Transport.
Runyan, Christiane
Co-Authors: Kenneth Belt, Christiane Runyan, William Greenwood, and Istvan Turcsanyi
Abstract: Fine particles in streams (seston), are important to lotic food webs, as substrates for pathogens and contaminants, and for microbial processes. Seston is composed of total suspended solids (TSS), and an organic fraction, measured as Fine Particulate Organic Matter (FPOM). We discuss TSS & FPOM concentrations and fluxes for several years of data for 16 streams of the BES LTER network. FPOM concentrations were greater in the catchments with the least and most dense storm drainage networks with the highest levels in the densest catchments. This bimodal distribution pattern across an urban drainage density gradient may be due to gutter mediated carbon and nutrient inputs and associated increases in stream productivity. Mean dry weather FPOM concentrations ranged from 0.4 mg/l (suburban) to 2.8 mg/l (forested), with the highest concentrations at the buried streams in storm drains. FPOM as a percentage of TSS ranged from ca. 13% (suburban) to ca. 31 % (forested), and was ca. 62% at a sewage impacted underground stream (Gwynns Run). We also examined the FPOM distribution within four size fractions. Most FPOM was retained by the 0.7 um filter and 53 um sieve, with lesser proportions found in the 250 and 1000 um sieves. This pattern was weaker at the underground stream storm drain sites where distribution among the four size classes was more equitable, suggesting a less processed state for this OM. These results suggest that urban catchments, with their altered drainage pathways and strong terrestrial-aquatic linkages, have FPOM levels similar to natural streams, with even higher levels for catchments with high storm drainage densities. This has important implications for aquatic food webs and productivity, and for pollutant fates.