Effect of nitrogen on the uptake of perchlorate by plants



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Texas Tech University


Previous studies have shown that plants were tolerant to perchlorate and will accumulate perchlorate in plant tissues. The objectives of this research were to determine the effect of nitrogen type (Ammonium or Nitrate) and concentration on the rate and extent of perchlorate uptake in lettuce and soybean plants. Studies were conducted in plant growth chambers and in greenhouses using sand as a support medium. Treatments included studies with defined laboratory fertilizer solutions at varying concentrations of nitrogen and constant concentrations of other ions, as well as with commercial NH4+ and NO3- based fertilizers at varying loading rates. The growth of plants was affected in response to varying nitrogen concentrations and sources. The perchlorate accumulation in plants was determined on a weekly basis by extracting the plant and sand samples and analyzing them for perchlorate levels using ion chromatography. In all experiments, plant growth was severely affected, and in most cases, plants did not proceed past the two leaf stage of growth. Perchlorate was detected in all plants with peak concentrations occurring between 3-6 weeks of growth and declining thereafter. The plant perchlorate concentrations were higher in plants fertilized with ammonium fertilizer than with the nitrate fertilizer although the difference in plant growth between treatments makes it difficult to say whether this would be observed under normal conditions. The perchlorate concentration also generally increased with an increase in nitrogen concentrations applied to the plants. Overall, the effects of source and nitrogen concentration are unlikely to have significant effects on perchlorate uptake in plants under normal environmental conditions.