Occurrence and sources of radium in groundwater associated with oil fields in the southern San Joaquin Valley, California
Environmental Science & Technology
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Abstract
Geochemical data from 40 water wells were used to examine the occurrence and sources of radium (Ra) in groundwater associated with three oil fields in California (Fruitvale, Lost Hills, South Belridge). 226Ra+228Ra activities (range=0.010-0.51 Bq/L) exceeded the 0.185 Bq/L drinking-water standard in 18% of the wells (not drinking-water wells). Radium activities were correlated with TDS concentrations (p<0.001, ρ=0.90, range=145-15,900 mg/L), Mn+Fe concentrations (p<0.001, ρ=0.82, range=<0.005-18.5 mg/L), and pH (p<0.001, ρ=-0.67, range=6.2-9.2), indicating Ra in groundwater was influenced by salinity, redox, and pH. Ra-rich groundwater was mixed with up to 45% oil-field water at some locations, primarily infiltrating through unlined disposal ponds, based on Cl, Li, noble-gas, and other data. Yet 228Ra/226Ra ratios in pond-impacted groundwater (median=3.1) differed from those in oil-field water (median=0.51). PHREEQC mixing calculations and spatial geochemical variations suggest the Ra in oil-field water was removed by co-precipitation with secondary barite and adsorption on Mn-Fe precipitates in the near-pond environment. The saline, organic-rich oil-field water subsequently mobilized Ra from downgradient aquifer sediments via Ra-desorption and Mn/Fe-reduction processes. This study demonstrates that infiltration of oil-field water may leach Ra into groundwater by changing salinity and redox conditions in the subsurface rather than by mixing with a high-Ra source.
Suggested Citation
McMahon, P.B., Avner Vengosh, Davis, T., Landon, M.K., Rebecca L. Tyne, Wright, M., Kulongoski, J.T., Hunt, A.G., Barry, P.H., Kondash, A., Wang, Z., Ballentine, C.J., 2019, Occurrence and sources of radium in groundwater associated with oil fields in the southern San Joaquin Valley, California: Environmental Science & Technology, v. 53, no. 16, p. 9398-9406, https://doi.org/10.1021/acs.est.9b02395.
ISSN: 1520-5851 (online)
Study Area
| Publication type | Article |
|---|---|
| Publication Subtype | Journal Article |
| Title | Occurrence and sources of radium in groundwater associated with oil fields in the southern San Joaquin Valley, California |
| Series title | Environmental Science & Technology |
| DOI | 10.1021/acs.est.9b02395 |
| Volume | 53 |
| Issue | 16 |
| Publication Date | August 07, 2019 |
| Year Published | 2019 |
| Language | English |
| Publisher | American Chemical Society |
| Contributing office(s) | California Water Science Center, Colorado Water Science Center, Crustal Geophysics and Geochemistry Science Center |
| Description | 9 p. |
| First page | 9398 |
| Last page | 9406 |
| Country | United States |
| State | California |
| Other Geospatial | San Joaquin Valley |