Metals and bacteria partitioning to various size particles in Ballona creek storm water runoff

Abstract

Abstract-Many storm water best management practice (BMP) devices function primarily by capturing particulate matter to take advantage of the well-documented association between storm water particles and pollutants. The hydrodynamic separation or settling methods used by most BMP devices are most effective at capturing medium to large particles; however, these may not be the most predominant particles associated with urban runoff. The present study examined particle size distribution in storm water runoff from an urban watershed in southern California and investigated the pollutant-particle associations of metals (Cu, Pb, Ni, and Zn) and bacteria (enterococci and Escherichia coli). During small storm events ( 0.7 cm rain), the highest concentration of pollutants were associated with a <6-mm filter fraction, which accounted for 70% of the per storm contaminant mass but made up more than 20% of the total particle mass. The pollutant-particle association changed with storm size. Most pollutant mass was associated with >35 mm size particles during a 5-cm rain event. These results suggest that much of the contaminant load in storm water runoff will not be captured by the most commonly used BMP devices, because most of these devices (e.g., hydrodynamic separators) are unable to capture particles smaller than 75 mm. Environ. Toxicol. Chem. 2013;32:320-328. # 2012 SETAC

Pollutant association with suspended solids in stormwater in Tijuana, Mexico

“…Suspended solids play an important role in the transport of anthropogenic nutrients and heavy metals in streams (Horowitz et al 2008). The concentration of sediment-bound contaminants varies with particle size, with large amounts attached to the finer particles (Taylor and Owens 2009;Brown et al 2013). Hvitved-Jacobsen et al (1994) found 60-80 % of phosphorus and lead, 50-60 % of nitrogen, and 30-40 % of zinc in road runoff to be associated with particulates.…”

The Importance of Particle Characterization in Stormwater Runoff

“…In their study, the highest concentration of pollutants was in the < 6 \im filter fraction, probably because of the pollutants in the dissolved phase being present in this phase. For this study, copper, nickel and zinc (same metals reported by Brown et al, 2013) have the highest influent concentration in the dissolved phase, which when added to the F2 (0.45-8 |xm) size fraction, gives a concentration higher than the F3 (8-20 |.im) size fraction.…”

“…The implication is that, bydrodynamic devices would not be appropriate to reduce the concentration of these pollutants, given that HD units remove only particles above 100 |im. Brown et al (2013) have made the same observation for urban runoff entering a creek in southern California. In their study, the highest concentration of pollutants was in the < 6 \im filter fraction, probably because of the pollutants in the dissolved phase being present in this phase.…”

“…Thus, the actual removal of particles will be smaller than the theoretically predicted. However, selection of treatment units based on the PSD of the stormwater to be treated has rarely been the case, as shown in the case of Ballona creek (Brown et al, 2013). Sediment Removal by Hydrodynamic Devices.…”

Wpływ pokrycia dachu na ilość i wielkość zawiesin w spływach deszczowych

“…Każde z zastosowanych rozwiązań materiałowych dachu może w odmienny sposób wpływać na jakość odprowadzanych wód opadowych. Jednym z istotnych zanieczyszczeń identyfikowanych w spływach są zawiesiny bę-dące nośnikiem innych zanieczyszczeń, w tym jonów metali ciężkich i domieszek mikrobiologicznych (Brown, Stein, Ackerman, Dorsey, Lyon i Carter, 2013). Wyniki badań Vaze'a i Chiewa (2004) wykazały, że transport mikrozanieczyszczeń odbywa się głównie z zawiesinami o średnicach mniejszych od 50 μm.…”