clean glass beaker. A NitraVer 5 Nitrate Reagent AccuVac Ampuls was then inserted upside down such that the score mark was well below the surface of the solutions. Pushed up against the side of the beaker, the ampul broke along the score mark withdrawing the solution from the beaker and into the ampul. The ampul was then inverted and swirled for a period of 1 minute to ensure complete mixture. After an additional reaction period of 5 minutes, the ampul was then inserted into the Hach DR3000 Spectrophotometer, also set to a wavelength of 400 nm and its absorbance (1/cm) recorded. To zero the instrument for this procedure, a vial filled with deionized water was inserted into the spectrophotometer and the “Zero” button pressed. For every successive standard solution however, the spectrophotometer had to be zeroed with a vial containing solution of the same concentration. For the samples, this meant zeroing the spectrophotometer using the sample water and then taking a reading of the ampul. contains the absorbance measurements obtained from each of the standard solutions. These measurements established a linear relationship, seen in , between the nitrate concentration of the standard solution and its absorbance. This calibration curve through interpolation of the water samples was used to determine the concentration of nitrogen as nitrate in each of the samples. Table : Absorbance measurements for nitrogen standard solutions Standard (mg/L) Absorbance (1/cm) 0 0.014 0.5 0.029 1 0.048 2 0.074 5 0.161 10 0.275 Figure : Nitrogen calibration curve from standard solutions Ammonia The last procedure utilizing the Hach DR3000 Spectrophotometer measured the concentration of ammonia present in the samples. A set of standards were created at concentrations of 0.2, 0.5, 1.0, and 3.0 mg/L of ammonia using an ampul containing a standard solution 50 mg/L of ammonia. Twenty-five (25) milliliters of the standard solution was poured
Appendix A: Sampling Locations Sample Description 10/5/2007 1 Up Time: 10:50 Location: Route 119 Pepperell-Groton bridge Lat./Long.: 45° 37' 35" 71° 35' 35" 2 Label: Pond A Time: 8:30 Location: 75 feet downstream of Pepperell boat ramp 50 feet away from boat ramp shore Depth: 5 feet Lat./Long.: 45° 39' 50" 71° 34' 39" 3 Label: Down Time: 10:13 Location: Covered bridge in Pepperell Lat./Long.: 45° 40' 11" 71° 34' 30" 4 Label: Pond B Time: 9:30 Location: 30 feet upstream of a at a point 10 feet offshore Surface Lat./Long.: 45° 39' 42" 71° 34' 42" 5 Label: Pond C Time: 9:30 Location: Middle of pond Depth: Surface Lat./Long.: 45° 37' 41" 71° 35' 37" Core 1 Time: 8:35 Location: 30 feet upstream of Pepperell boat ramp 20 feet away from boat ramp shore Lat./Long.: 45° 39' 50" 71° 34' 39" Core 2 Time: 9:30 Location: 30 feet upstream of a house at a point 10 feet offshore Lat./Long.: 45° 39' 42" 71° 34' 42"
Core 3 Time: 10:27 Location: 40 feet upstream of Groton boat ramp 20 feet offshore Lat./Long.: 45° 37' 41" 71° 35' 37" 6 Description: Ice House Location: Ice House Dam Impoundment 11/29/2007 7 Label: Ice House Up (IHU) Time: 13:30 Location: 5 feet upstream of Ice Dam impoundment 20 feet offshore Lat./Long.: 45° 33' 10" 71° 37' 9" 8 Ice House Down (IHD) Time: 13:30 Location: 100 feet downstream of Ice House Dam Impoundment 15 feet offshore Lat./Long.: 45° 33' 11" 71° 37' 5" 9 Label: 9 Time: 14:00 Location: Route 119 Pepperell-Groton bridge Lat./Long.: 45° 37' 35" 71° 35' 35" 10 Label: 10 Time: 14:15 Location: Launch Ramp for Pepperell Pond Pepperell, MA Lat./Long.: 45° 39' 48" 71° 34' 40" 11 Label: 11 Time: 14:45 Location: Covered bridge in Pepperell Lat./Long.: 45° 40' 11" 71° 34' 30" Appendix B: Alkalinity Results Sample 1: Vinitial(L): 0.100 Alkalinity (meq/L)= 0.7098 Alk (mg/L CaCO3)= 36 volume added pH Volume, uL meq/L [H+] R2 Alkalinity (meq/L) 0 7.05 0 0 9.24E-08 #DIV/0! 240 5.9 300 0.48 1.30E-06 0.9733 0.1545 280 5.64 350 0.56 2.37E-06 0.9137 0.2766 320 5.3 400 0.64 5.19E-06 0.8648 0.3987 340 5.03 425 0.68 9.67E-06 0.8478 0.4887 360 4.64 450 0.72 2.37E-05 0.7526 0.5860