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

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 5km from the production unit over a period of 12 months (2014, June - 2015, May) were screened for ClO. During the period, ClOconcentration in ground water samples close to the production unit increased to >40,000μg/L, and ClO was detected at 1740μg/L in well water 1.6km away from the production unit. A community pond in the area also showed an increase in ClO level up to 29,000μg/L. In all water sources, ClO level was maximum during the rainy season (July, monsoon). A natural degradation of ClO 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 ClO exposure. The plant accumulated ClO up to 600.8mg/kg wet weight with a Bio-Concentration Factor 2.06±0.005. This is the first report on spatio-temporal distribution of ClO at higher levels in a natural environment and its toxicity response to plants under natural condition.