Lecture 7 - Overview Lecture #7 Overview What are common...

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Overview ± Lecture #7 ± Risk and Contaminant Concentrations ± NAAQS (ppmv) and MCLs (ppm) (ICP#4,5) ± Flow and Flux Units (ICP#6) ± Reading: V: Ch. 2 (pg 26-28); course pack N: 1.C.1 (pg. 7-10) Overview ± What are common concentrations units for water and air pollutants? ± How does one convert weight per weight (e.g., ppmw) or volume per volume (e.g., ppmv) concentration units to weight per unit volume (e.g., mg/m 3 or mg/L) units? (ICP#4,5) ± What is volumetric flow rate and mass flow rate? ± How does one convert between flow and flux units? (ICP#6) Risk Assessment ± risk evaluation is performed in terms of the probability for an individual to suffer an adverse effect (e.g., cancer or toxic response) from exposure to a chemical ± risk = f (hazard, exposure) ± hazard: toxic properties of a chemical ± exposure: ingestion, inhalation, or dermal ± we need to be able to model exposure from emission source to receptor (i.e., human or other target of concern) ± mass balance equation models ± but first back to NAAQS and MCLs (concentration units!) that we will be modeling see V: Ch 2 (SI units and conversions) NAAQS (ppmv or mg/m 3 ) MCLs (mg/L or ppm) b Maximum Contaminant Level (MCL); c Maximum Contaminant Level Goal; e million fibers per liter Air Quality Concentrations (ppmv) ± PV = nRT (ideal gas law) ± P: pressure (Pa; 1 atm = 1.01325 x 10 5 Pa) ± T: temperature (ºK = ºC + 273.15) ± R: gas constant (8.314 J-mol -1 K -1 =8.205x10 -5 atm-m 3 - mol -1 K -1 ) ± Σ i P i =P; Σ i V i = V; Σ i n i = n ± P = (n/V)RT; P i = (n i /V)(RT) ± Likewise V = (n/P)(RT); V
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Lecture 7 - Overview Lecture #7 Overview What are common...

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