Measuring dissolved oxygen in a body of water is necessary to determine whether or not it has enough oxygen content in order to be habitable to various aerobic organisms and marine life. This measurement gives us the amount of oxygen content per unit of volume (usually mg/L), and from this, we are able to determine the type of organisms that can thrive there. This concentration is dependent upon the salinity and chlorinity of the water, as well as the temperature, atmospheric pressure, flow rate, and distance along the stream from the deoxygenated parts of the water. The purpose of this laboratory assignment is to collect data about the concentration of dissolved oxygen in ...view middle of the document...
It should be noted that we started downstream so as to not disturb the stream at the other points, because any disturbance may significantly alter the readings. We were also careful to only insert the probe of the meter to where it was just barely touching the bottom of the pipe in order to mitigate further disturbances.
3) The process was repeated for the third, second, and first points in the seventh channel.
4) After finishing the readings in the seventh channel, one team member recorded the flow rate from the end of channel seven where the streamed emptied into a collection bucket by placing the graduated cylinder under the end of the channel for approximately 10 seconds, as ordered by another team member controlling the stopwatch. After this, the graduated cylinder was set on a flat surface to settle, and then a reading was taken and divided by ten (10), in order to get the flow rate per second, Q, for channel seven.
5) Channels six-through-two were much smaller than channel seven, so the process was abbreviated somewhat by inserting the DO meter into the midpoint of each channel for the concentration measurements, giving us a single C reading per channel, and then taking more Q (flow rate) readings via the graduated cylinder and stopwatch in the drops between the channels. These processes were repeated until the C and Q values for each channel (excluding channel one) were successfully recorded.
6) For channel one, we approached it the same way as we did for channel seven. There were four points where the concentration was recorded, and the flow rate at the end of channel one was recorded.
7) After the Q and C values have all been recorded, we measured the horizontal distances between the points. For channel seven, we measured the distance between the first point on the channel and the fourth point. We then repeat this process for the other two points on the channel. We should also note that our x = 0 value simply corresponds to the first point in channel seven.
8) After measuring the horizontal distances on the channel, we then measured the vertical distance between the sixth and the seventh channel. This is our drop height and corresponds the C and x values for the drop.
9) We repeated this process until the drop between the first and second channels was recorded. Our x = 0 values for each drop are simply the C values at the midpoints of each previous channel.
10) Then, for the first channel, we performed the same procedure that was performed on channel seven to obtain the x-values. After this, the data collection for the experiment was complete.
Experimental Data and Discussion:
Table 1 |
Channel # | x (cm) | C (mg/L) | (Cs-C)/ (Cs-C0) | LN((Cs-C)/ (Cs-C0)) |
1 | 0 | 0.68 | 1.0000 | 0.0000 |
| 102 | 0.69 | 0.9988 | -0.0012 |
| 169 | 0.80 | 0.9856 | -0.0145 |
| 250 | 0.80 | 0.9856 | -0.0145 |
7 | 0 | 5.72 | 1.0000 | 0.0000 |
| 102 | 5.85 | 0.9602 | -0.0406 |
| 169 | 5.86 | 0.9572 |...