* Replicate samples
**Sample L2, with a high measured lead content, was not included in the plot average for 27 Linden St.

Methodology

A total of thirteen vacant lots were sampled in two days. Each lot was measured and marked with an X-transect. Surface soil samples were scooped into plastic baggies every 10 – 20 feet (the distance between each sample and the number of samples taken varied according to the size of the lot) along the transect. Visual assessments of the lots were noted in the charts drawn for each lot (litter, debris, surrounding houses, etc). Contiguous lots, 42 Harvard Avenue and 44-40 Harvard Avenue, were sampled with one large transect that covered both lots. I was unable to test certain lots because of the following: used as off street parking so that parked cars prohibited access to soil, concrete slabs or other large debris limited access, many of the 21 original lots had a fresh layer of top soil so that the presence of contamination was unlikely, one lot was not tested because there was a fight breaking out on it so for safety’s sake I avoided testing it that day.

Once all of the samples were collected, I air dried each sample for 24 hours. After air-drying, I sieved each sample with a 2mm sieve and oven dried them for another 24 hours. I then pulverized the samples and ground them together with 15% binder (copolymer wax) and 85% sample by weight so that each sample was approximately 5 grams. The samples were then pressed into press powdered pellets. The samples were analyzed using a Philips Sequential X-Ray Fluorescent spectrometer and the data was reduced using Uniquant 5.

The samples were tested for heavy metals, specifically lead, copper, cadmium, chromium and arsenic. According the Rhode Island Department of Environmental Management’s standards for copper, cadmium, and chromium, my soil samples did not show any significant levels of any of these metals. The standard level of arsenic (1.7 ppm) was not detectable using the Uniquant system (not sensitive enough to pick up these smaller amounts) thus I was unable to determine the presence of arsenic in the soil samples. Two samples of Montana Soil (SRM2711) were measured several times during the analysis of my samples. The published value for lead for this soil is 1162 ppm. The mean and standard deviations of the standards can be compared to the published amount to get an idea of the precision of my measurements. Also, one can compare the values between all the standard samples to get a sense of the accuracy of the measurement for the same sample. Certain soil samples were run twice (indicated with an asterisk in Table) and again one can get a sense of the accuracy by comparing the results of two runs of the same sample.

The lead concentrations originally reported in this table were determined to be elevated due to an inaccurate calibration of the XRF. After recalibration and some preventative maintenance the samples were reanalyzed by David Murray in July 2000.  With perimission, this table was updated with the revised measurements on March 25, 2004. A comparison of the original and revised data yields the following linear correction: Pb revised (ppm) = 0.59 * Pb original (ppm) + 12.7.