NCJ Number
60700
Date Published
1979
Length
16 pages
Annotation
FINDINGS ARE REPORTED FROM AN ANALYSIS OF POLYCYCLIC AROMATIC HYDROCARBONS (PAH) IN SOILS TO DETERMINE IF THE AMOUNT AND COMPOSITION OF PAH IN SOILS VARY WITH LOCATION.
Abstract
THE MAIN SOURCE OF PAH IN SOILS ARE THE AIR-BORN PARTICLES FORMED IN VARIOUS COMBUSTION PROCESSES (AUTOMOBILE EXHAUST, COMBUSTION OF OILS, COAL, REFUSE, ETC.). THE AMOUNT AND COMPOSITION OF PAH IN A SOIL SAMPLE SHOULD VARY WITH THE PLACE FROM WHICH THE SAMPLE WAS COLLECTED. THIS CAN MAKE THE ANALYSIS OF PAH USEFUL IN THE FORENSIC EXAMINATION OF SOILS. TO TEST THE HYPOTHESIS, SOIL SAMPLES, EACH WEIGHING ABOUT 20 GRAMS, WERE COLLECTED FROM SURFACE LAYERS (ABOUT ONE CENTIMETER IN DEPTH) OF TOPSOILS. THE SAMPLES WERE AIR-DRIED AT ROOM TEMPERATURE, CRUSHED IN AN AGATE MORTAR AND PASSED THROUGH A SIEVE. AFTER HOMOGENATION, 0.5 GRAMS OF EACH SAMPLE WAS SUSPENDED IN METHANOL AND SHAKEN. THE SUPERNATANT SOLUTION WAS ANALYZED BY HIGH-PRESSURE LIQUID CHROMATOGRAPHY. RESULTS SHOWED THAT DISCRIMINATION BETWEEN SOILS FROM DENSELY POPULATED AREAS AND THOSE FROM RURAL AREAS CAN BE ACHIEVED, SINCE THE TOTAL AMOUNT OF PAH IN URBAN SOILS IS MUCH HIGHER. THERE IS NO APPARENT CORRELATION BETWEEN PAH CONTENT AND DRY-SOIL COLOR. THE CHANGES IN PAH COMPOSITION WITH SAMPLE LOCATION ARE GRADUAL, THAT CHROMATOGRAMS OBTAINED FOR SAMPLES FROM THE SAME PLACE MAY BE USED LIKE FINGERPRINTS. THE MAIN LIMITATION OF THE METHOD IS THE RISK OF CONTAMINATION OF SAMPLES TAKEN FROM SUSPECTS. FURTHER, THE DISCRIMINATING CAPACITY FOR SOILS FROM RURAL AREAS IS RELATIVELY POOR. GRAPHIC DATA AND REFERENCES ARE PROVIDED. (RCB)