Srinagar: Water chestnuts harvested from Kashmir’s Dal Lake contain elevated levels of certain heavy metals, including cadmium and zinc, with concentrations in the edible fruit exceeding guideline limits cited in a recent scientific study, raising concerns over contamination in aquatic food sources.
The findings were reported in a study published in Scientific Reports, which examined water, sediment and water chestnut (Trapa natans) samples collected from four major water bodies of Jammu and Kashmir — Dal Lake, Hokersar Wetland, Manasbal Lake and Wular Lake.
According to the study, Dal Lake recorded the highest levels of heavy metal accumulation, followed by Hokersar, Manasbal and Wular lakes, indicating a clear pollution gradient across the sampled water bodies.
Researchers found that water chestnut fruits collected from Dal Lake contained cadmium concentrations of 0.11 mg/kg, significantly higher than the 0.02 mg/kg limit referenced in the study. Zinc levels in the edible fruit reached 18.21 mg/kg, also exceeding the guideline value cited by the researchers.
However, the study does not establish a direct link between consumption of water chestnuts from Dal Lake and any specific health effects. Instead, the authors emphasised the need for continued monitoring of contaminants in aquatic food products and their potential movement through the food chain.
The research showed that heavy metals accumulated most strongly in the roots of the water chestnut plant, followed by shoots and fruits, suggesting that a large proportion of contamination remains concentrated within the plant’s root system.
Iron was the most abundant element detected. In samples from Dal Lake, iron concentrations in roots reached 322.50 mg/kg, while zinc concentrations in roots were recorded at 82.45 mg/kg. Cadmium levels in roots reached 0.42 mg/kg.
The study also highlighted significant differences among the water bodies. Wular Lake recorded the lowest concentrations of heavy metals, while Manasbal Lake also showed comparatively lower contamination levels. Researchers attributed these variations to differences in pollution sources, hydrological conditions and water exchange processes.
Sediment analysis revealed that Dal Lake also had the highest enrichment of heavy metals. Several elements, including cadmium, chromium, nickel and iron, were found to exceed Canadian sediment-quality guideline thresholds in some sediment samples.
The researchers noted that water chestnut could serve as a useful biological indicator of aquatic pollution due to its ability to absorb and accumulate heavy metals. They suggested that the plant may also have potential applications in phytoremediation, a process that uses plants to remove contaminants from the environment.
