Passage V were removed from the remain- Runoff from an urban area carries suspen
ID: 234609 • Letter: P
Question
Passage V were removed from the remain- Runoff from an urban area carries suspended and dising portion All the TSS rtion of each of Water Samples 1-14. The diameters solved pollutants into nearby streams. Three studies exam- ined the total suspended solids (TSS), total dissolved solids (TDS), and chemical oxygen demand (COD) in the runoff to 5 classes. The percent by mass from a 55-hectare area of a city. Some of any portion of the suspended and dissolved solids in urban runoff is organic matter: COD represents the mass of oxygen needed to oxi- dize the organic matter in a 1 L water sample. particles, in micrometers (pum). were measured ids and those measurements were ss of the TSS particles each class was then determined (see Figure 2) TSS particle diameter p>2500um-250.0 125.1 .m-250.0m 62.6 m-125.0 m 321 nn_ 62.5 m For each of 6 rain events during 1 summer, water sam- ples were collected at the sewer outlet that carried all the runoff away from the area. Once every 5 min while rain was falling, an automated sampling device collected I L of water, starting 5 min after the rain began. A portion of each sample was combined with an equal portion of each of the other samples from that rain event, and the combined por- tions were analyzed for TSS, TDS, and COD concentra- tions (see Table 1) Duration Rain of rainfall Concentration (mg/L) of: 12345 6789 10 11 12 13 14 Water Sample Event (min) TSS TDS COD 96 230 223 108 Table and figures adapted from José Anta et al., "A BIP select on Process Based on the Granulometry of Runoff Solids in a Separate Urban Catchment." 02006 by the Water Research Commission An equal portion of each of the 14 water samples col- lected during Rain Event 2 (Water Samples 1-14) was ana- lyzed for TSS concentration. The rate of water flow from e sewer outlet was also determined at each of the sam- pling times (see Figure 1) TSS concentration .. water flow rate 30. Based on the description of COD in the passage, the suspended and dissolved solids in the runoff from which rain event in Study 1 most likely had the highest organic matter content? F. Rain Event 1, because the runoff from that event G. Rain Event 1, because the runoff from that event H. Rain Event 3, because the runoff from that event J. Rain Event 3, because the runoff from that event had the highest COD concentration. had the lowest COD concentration. had the highest COD concentration had the lowest COD concentration. 1234 5678 9 1011 12 13 14Explanation / Answer
30.H
31.B
32.F
33.B
34.G
35.B