Format

Send to

Choose Destination
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.

Author information

1
Department of Civil, Environmental, and Construction Engineering, Texas Tech University, Lubbock, TX 79409-1023, USA.
2
National Research Program, U.S. Geological Survey, Reston, VA 20192, USA.
3
Department of Geological Sciences, University of Delaware, Newark, DE 19716, USA.
4
Environmental Sciences Division, Oak Ridge National Laboratory, Oak Ridge, TN, USA.
5
U.S. Air Force, ASC/ENVR, Wright-Patterson AFB, OH 45433, USA.
6
U.S.D.A. - A.R.S., Plant Sciences Research Unit, North Carolina State University, Raleigh, NC 27607, USA.
7
Department of Botany and Plant Sciences, University of California, Riverside, Kearney Agricultural Center, Parlier, CA 93648, USA.
8
Plant Pathology & Plant-Microbe Biology Section, SIPS, Cornell University, Long Island Horticultural Research and Extension Center, Riverhead, NY 11901, USA.
9
Department of Environmental Toxicology, The Institute of Environmental and Human Health (TIEHH), Lubbock, TX 79409-1163, USA.
10
CB&I Federal Services, Lawrenceville, NJ 08648, USA.
11
Department of Civil, Environmental, and Construction Engineering, Texas Tech University, Lubbock, TX 79409-1023, USA. Electronic address: andrew.jackson@ttu.edu.

Abstract

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.

KEYWORDS:

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

PMID:
28399495
DOI:
10.1016/j.scitotenv.2017.03.223
[Indexed for MEDLINE]

Supplemental Content

Full text links

Icon for Elsevier Science
Loading ...
Support Center