Spatio-temporal distribution of perchlorate and its toxicity in Hydrilla verticillata

- Perchlorate >40,000 μg/L found in ground water sources close to a production plant.
- The contamination observed up to 1.6 km away in one-year period.
- Monsoon period recorded highest ClO4− contamination in ground water.
- H. verticellata in a contaminated pond decayed and accumulated ~60 mg ClO4−/kg wt..

The spatio-temporal distribution of perchlorate in water sources around an ammonium perchlorate production unit and its toxicity response on a dominant aquatic plant, Hydrilla verticillata are reported in this study. Samples (n=453) from ground water (open well) and surface water sources within 5 km from the production unit over a period of 12 months (2014, June − 2015, May) were screened for ClO4−. During the period, ClO4−concentration in ground water samples close to the production unit increased to >40,000 μg/L, and ClO4− was detected at 1740 μg/L in well water 1.6 km away from the production unit. A community pond in the area also showed an increase in ClO4− level up to 29,000 μg/L. In all water sources, ClO4− level was maximum during the rainy season (July, monsoon). A natural degradation of ClO4− was not observed in the area as evident from its persistent level and spreading to more areas. H. verticillata, the dominant vegetation in the pond exhibited severe toxic response like massive decay and loss of photosynthetic pigments such as chlorophyll and carotene due to ClO4− exposure. The plant accumulated ClO4− up to 60±0.8 mg/kg wet weight with a Bio-Concentration Factor 2.06±0.005. This is the first report on spatio-temporal distribution of ClO4− at higher levels in a natural environment and its toxicity response to plants under natural condition.

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