J.K. Bohlke Neil C. Sturchio Baohua Gu Greg Harvey Kent O. Burkey David A. Grantz Margaret T. McGrath Todd A. Anderson Balaji Rao Ritesh Sevanthi Paul B. Hatzinger W. Andrew Jackson Nubia Luz Estrada 2017 <p><span>Natural perchlorate (ClO</span>₄⁻<span>) in soil and groundwater exhibits a wide range in stable isotopic compositions (δ</span>³⁷<span>Cl, δ</span>¹⁸<span>O, and Δ</span>¹⁷<span>O), indicating that ClO</span>₄⁻<span> may be formed through more than one pathway and/or undergoes post-depositional isotopic alteration. Plants are known to accumulate ClO</span>₄⁻<span>, but little is known about their ability to alter its isotopic composition. We examined the potential for plants to alter the isotopic composition of ClO</span>₄⁻<span> in hydroponic and field experiments conducted with snap beans (</span><i>Phaseolus vulgaris</i><span> L.). In hydroponic studies, anion ratios indicated that ClO</span>₄⁻<span> was transported from solutions into plants similarly to NO</span>₃⁻<span> but preferentially to Cl</span>⁻<span> (4-fold). The ClO</span>₄⁻<span> isotopic compositions of initial ClO</span>₄⁻<span> reagents, final growth solutions, and aqueous extracts from plant tissues were essentially indistinguishable, indicating no significant isotope effects during ClO</span>₄⁻<span> uptake or accumulation. The ClO</span>₄⁻<span> isotopic composition of field-grown snap beans was also consistent with that of ClO</span>₄⁻<span> in varying proportions from irrigation water and precipitation. NO</span>₃⁻<span> uptake had little or no effect on NO</span>₃⁻<span> isotopic compositions in hydroponic solutions. However, a large fractionation effect with an apparent ε (</span>¹⁵<span>N/</span>¹⁸<span>O) ratio of 1.05 was observed between NO</span>₃⁻<span> in hydroponic solutions and leaf extracts, consistent with partial NO</span>₃⁻<span> reduction during assimilation within plant tissue. We also explored the feasibility of evaluating sources of ClO</span>₄⁻<span> in commercial produce, as illustrated by spinach, for which the ClO</span>₄⁻<span> isotopic composition was similar to that of indigenous natural ClO</span>₄⁻<span>. Our results indicate that some types of plants can accumulate and (presumably) release ClO</span>₄⁻<span> to soil and groundwater without altering its isotopic characteristics. Concentrations and isotopic compositions of ClO</span>₄⁻<span>and NO</span>₃⁻<span> in plants may be useful for determining sources of fertilizers and sources of ClO</span>₄⁻<span> in their growth environments and consequently in food supplies.</span></p> application/pdf 10.1016/j.scitotenv.2017.03.223 en Elsevier Stable isotopic composition of perchlorate and nitrate accumulated in plants: Hydroponic experiments and field data article