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Sci Total Environ. 2017 Oct 1;595:556-566. doi: 10.1016/j.scitotenv.2017.03.223. Epub 2017 Apr 8.

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

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Department of Civil, Environmental, and Construction Engineering, Texas Tech University, Lubbock, TX 79409-1023, USA.
National Research Program, U.S. Geological Survey, Reston, VA 20192, USA.
Department of Geological Sciences, University of Delaware, Newark, DE 19716, USA.
Environmental Sciences Division, Oak Ridge National Laboratory, Oak Ridge, TN, USA.
U.S. Air Force, ASC/ENVR, Wright-Patterson AFB, OH 45433, USA.
U.S.D.A. - A.R.S., Plant Sciences Research Unit, North Carolina State University, Raleigh, NC 27607, USA.
Department of Botany and Plant Sciences, University of California, Riverside, Kearney Agricultural Center, Parlier, CA 93648, USA.
Plant Pathology & Plant-Microbe Biology Section, SIPS, Cornell University, Long Island Horticultural Research and Extension Center, Riverhead, NY 11901, USA.
Department of Environmental Toxicology, The Institute of Environmental and Human Health (TIEHH), Lubbock, TX 79409-1163, USA.
CB&I Federal Services, Lawrenceville, NJ 08648, USA.
Department of Civil, Environmental, and Construction Engineering, Texas Tech University, Lubbock, TX 79409-1023, USA. Electronic address:


Natural perchlorate (ClO4-) in soil and groundwater exhibits a wide range in stable isotopic compositions (δ37Cl, δ18O, and Δ17O), indicating that ClO4- may be formed through more than one pathway and/or undergoes post-depositional isotopic alteration. Plants are known to accumulate ClO4-, but little is known about their ability to alter its isotopic composition. We examined the potential for plants to alter the isotopic composition of ClO4- in hydroponic and field experiments conducted with snap beans (Phaseolus vulgaris L.). In hydroponic studies, anion ratios indicated that ClO4- was transported from solutions into plants similarly to NO3- but preferentially to Cl- (4-fold). The ClO4- isotopic compositions of initial ClO4- reagents, final growth solutions, and aqueous extracts from plant tissues were essentially indistinguishable, indicating no significant isotope effects during ClO4- uptake or accumulation. The ClO4- isotopic composition of field-grown snap beans was also consistent with that of ClO4- in varying proportions from irrigation water and precipitation. NO3- uptake had little or no effect on NO3- isotopic compositions in hydroponic solutions. However, a large fractionation effect with an apparent ε (15N/18O) ratio of 1.05 was observed between NO3- in hydroponic solutions and leaf extracts, consistent with partial NO3- reduction during assimilation within plant tissue. We also explored the feasibility of evaluating sources of ClO4- in commercial produce, as illustrated by spinach, for which the ClO4- isotopic composition was similar to that of indigenous natural ClO4-. Our results indicate that some types of plants can accumulate and (presumably) release ClO4- to soil and groundwater without altering its isotopic characteristics. Concentrations and isotopic compositions of ClO4- and NO3- in plants may be useful for determining sources of fertilizers and sources of ClO4- in their growth environments and consequently in food supplies.


Chlorine isotopes; Irrigation; Isotope fractionation in snap beans (Phaseolus vulgaris L.); Nitrogen isotopes; Oxygen isotopes; Plant uptake

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