Evaluation of Perchlorate Sources in the Rialto-Colton and Chino California Subbasins using Chlorine and Oxygen Isotope Ratio Analysis

Abstract

T he public reporting burden for this collection of information is estimated to a ven:~~ge 1 hour per response. including t he time for reviewing instruction-;. search ing exist ing dat a sources. gathering and maintaining t he data needed. end completing and review ing th e collection of information_ Send comments reg arding t his burden estimate or any othe . Perchlorate in groundwater can be from synthetic or natmal sources. the latter of which include both historical application of impotted nitrate fertilizers fi·om the Atacama Desert of Chile and atmospheric perchlorate. The objective of this study was to evaluate the use of isotopic data to distinguish somces of perchlorate in groundwater in a specific region of the Rialto-Colton and Chino. CA groundwater subbasins. Perchlorate extrac ted from wells in tlus region was analyzed for chlorine and oxygen stable isotope ratios and radioactive chlorine-36 isotopic abundance. along w ith other geochenucal. isotopic. and hydrogeologic data. The stable isotope and chlOI~ne-36 data provided relatively unambiguous discrinunation of synthetic and Atacama perchlorate sources in most wells having relatively high concentt·ations. providing regional perspective on anthl'Opogenic perchlorate contamination in the Rialto-Colton and Cluno subbasins. Where indigenous natmal perchlorate was indicated as a substantial component. total perchlorate concentt·ations were low and concentrations of anthropogenic components were near backgrotmd levels.

Stable isotopic composition of perchlorate and nitrate accumulated in plants: Hydroponic experiments and field data

“…Given the low concentration of ClO 4 in groundwater used for irrigation at the Long Island experiment location (~ 0.3 μg/L), any combination of two or more sources would not be unreasonable. Similar ClO 4 isotopic compositions have been reported for groundwater with similarly low ClO 4 concentrations from mixed sources in southern California (Hatzinger et al, 2015;Sturchio et al, 2014). Our data indicate that it may be possible to evaluate foliar ClO 4 isotopic composition and origin in field-grown plants, even with near-background foliar ClO 4 concentrations (< 400 μg/kg dry weight).…”

“…and surface waters of the Great Lakes, and to the inferred isotopic composition of natural ClO 4 in groundwater in parts of southern California ( Figure 5) (Jackson et al, 2010;Böhlke et al, 2005;Hatzinger et al, 2015;Sturchio et al, 2006;Sturchio et al, 2014;Poghosyan et al, 2014).…”

Abiotic Reduction of Nitrate and Chlorate by Green Rust

“…− and ClO x − on Mars and other solar bodies is unclear but could be due to similar reactions as well as other reactions not pertinent to the earth. 9,10 Once formed, ClO 4 − , ClO 3 − , and NO 3 − may undergo transformation via biological or chemical processes. Bacteria use ClO 4 − , ClO 3 − , and NO 3 − as electron acceptors under anoxic conditions, and ClO 3 − and NO 3 − can be transformed by plants.…”

“…Differences in chlorine and nitrogen oxyanion ratios in these environments could be due to the relative contributions of production mechanisms or post-formation stability of these species. On the earth, ClO 4 – , and to a smaller degree ClO 3 – , is mainly produced in the stratosphere by O 3 or UV oxidation based on 36 Cl and Δ 17 O composition. − NO 3 – production, excluding direct and indirect anthropogenic contributions, is also attributed to UV and O 3 oxidation. Due to the lack of isotopic composition data, the production mechanism(s) responsible for NO 3 – and ClO x – on Mars and other solar bodies is unclear but could be due to similar reactions as well as other reactions not pertinent to the earth. , Once formed, ClO 4 – , ClO 3 – , and NO 3 – may undergo transformation via biological or chemical processes.…”

“…On the earth, ClO 4 – , and to a smaller degree ClO 3 – , is mainly produced in the stratosphere by O 3 or UV oxidation based on 36 Cl and Δ 17 O composition. − NO 3 – production, excluding direct and indirect anthropogenic contributions, is also attributed to UV and O 3 oxidation. Due to the lack of isotopic composition data, the production mechanism(s) responsible for NO 3 – and ClO x – on Mars and other solar bodies is unclear but could be due to similar reactions as well as other reactions not pertinent to the earth. , Once formed, ClO 4 – , ClO 3 – , and NO 3 – may undergo transformation via biological or chemical processes. Bacteria use ClO 4 – , ClO 3 – , and NO 3 – as electron acceptors under anoxic conditions, and ClO 3 – and NO 3 – can be transformed by plants .…”