Water-Resources Investigations Report 98-4016
Concentrations of arsenic exceed the New Jersey State Cleanup Criterion of 20 parts per million in sandy and clay-rich soils of two residential areas in the vicinity of the Imperial Oil Company Superfund site in Marlboro Township, Monmouth County, New Jersey. Industrial activities at this Superfund site included possible roasting of arsenical ores and the production of arsenical pesticides from about 1917 to 1945; arsenic concentrations that greatly exceed 20 parts per million have been measured in soils at the Superfund site. Although the Imperial Oil Company Superfund site potentially is a source of the arsenic found in the soils of nearby residential areas, identification of the source is complicated by the presence of minerals in the geologic substrate that can contain arsenic, and possible past use of arsenical pesticides in the orchards upon which the residential areas were built. Residential area 1 is adjacent to the Superfund site; residential area 2 is 0.5 mile to the north-northeast and was developed on former orchard land.In order to determine the source of the arsenic and metals in soils in the two residential areas, soil samples were collected from (1) long-term forested areas, to determine background geologic and regional atmospheric inputs of arsenic and metals; (2) former and current orchards, to assess the range of concentrations of arsenic and metals that could be contributed by past use of pesticides; (3) the Imperial Oil Company Superfund site, to characterize the chemical composition of contamination from activities at the site; (4) a wooded area adjacent to the Superfund site, to determine whether arsenic and metals from the Superfund site were evident; and (5) the two residential areas, to compare soil chemistry in these areas with the chemistry of soils from forests, orchards, and the Superfund site. The soil samples were divided by soil horizon and were analyzed for 23 metals and metaloids, total organic carbon, and total sulfur. Results of chemical analyses were stratified by horizon and analyzed statistically to compare data sets among land uses. A chemical signature for A-horizon soils in each "endmember" land-use group (undeveloped, geologic and regional atmospheric input; orchard, pesticide input; and Imperial Oil Company Superfund site, industrial input) was developed by using graphical methods and multivariate statistical procedures. Additionally, air-flow models were used to determine whether roasting of arsenic at the Imperial Oil Company Superfund site was a possible source of arsenic in the soils. The precision and accuracy of the soil analyses achieved by the laboratories did not meet the low analytical uncertainty required in the workplan developed at the beginning of the study, and analytical difficulties prevented use of data for a few analytes. Nor was it possible to collect undisturbed, contaminated soil samples from the Imperial Oil Company Superfund site, as specified in the workplan. Nevertheless, despite these modifications to the workplan, the chemistry of soils from the various land-use groups was sufficiently different that groups of samples could be statistically distinguished from each other on the basis of chemistry, and representative samples of soil horizons from the disturbed soils at the Imperial Oil Company Superfund site could be identified. Therefore, it was posssible to identify background concentrations of arsenic, lead, and other metals, orchard inputs of the same metallic substances, and effects of former industrial activities at the Imperial Oil Company Superfund site on residential soils, where these existed. Results of the analyses of soils from undeveloped forested areas indicated that background (geologic and regional atmospheric) concentrations of arsenic generally are small (less than 10 parts per million (or mg/kg (milligrams per kilogram)) in sandy soils but concentrations up to about 40 mg/kg were measured in clays. Sandy orchard soils contained more arsenic (median 12 mg/kg) than did sandy undeveloped forest soils (median 5 mg/kg). Arsenic concentrations in soil samples collected in the wooded area adjacent to the Imperial Oil Company Superfund site were found to be within the range measured for undeveloped forested areas, although the median value for soils from the A horizon was slightly higher than the median for background concentrations in A-horizon soils. Soil samples collected at the Superfund site as part of the study reported here generally contained elevated concentrations of arsenic, barium, copper, and lead (up to 114, 106, 167, and 284 mg/kg, respectively); concentrations of these constituents in previously collected soil samples also were highly elevated. The chemical signature of A-horizon soil samples from residential area 1, although similar, overall, to the signature of orchard soils, showed similarities to the chemical signature of soils at the Imperial Oil Company Superfund site in that concentrations of barium and copper were large. The chemical signature of A-horizon soil samples from residential area 2 also was statistically similar to the chemical signature of A-horizon soil samples from orchards. Results of the air-flow simulations indicated that emissions from smokestacks at the Imperial Oil Company Superfund site are unlikely to have deposited arsenic as fallout on soils at residential area 2. Soil samples from residential area 1, adjacent to the Imperial Oil Company Superfund site, contained cinders and brick debris similar to that found onsite. The results of the investigations indicate that arsenic concentrations above background in upper soil horizons in residential area 2 probably are the result of former pesticide use and that arsenic also is contributed by geologic materials, whereas elevated arsenic concentrations in residential area 1 soils adjacent to the Imperial Oil Company Superfund site appear to be related in part to earth-moving activities at the site.
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Barringer, J.L., Szabo, Zoltan, and Barringer, T.H., 1998, Arsenic and metals in soils
in the vicinity of the Imperial Oil Company Superfund site, Marlboro Township, Monmouth County,
New Jersey: U.S. Geological Survey Water-Resources Investigations Report 98-4016, 251 p.
Study approach and methods
Soil-profile characteristics and mineralogy at sample-collection sites
Distribution of arsenic and metals in soils
Relations of soil characterisitics and concentrations of arsenic and metals to land use
Sources of arsenic and metals in soils
Summary and conclusions
Appendix 1--Summary of analytical methods and chemical and field data for soil samples collected during 1995-96,
Imperial Oil Company Superfund site study area, New Jersey
Appendix 2--Sample collection, preparation, and documentation
Appendix 3--Preliminary air-emission model
Appendix 4--Quality assurance
Appendix 5--Statistical analysis of chemical data