Accumulation of eight heavy metals in water chestnut (Trapa natans L.) of four major water bodies of Jammu and Kashmir, India

Freshwater lakes in Jammu and Kashmir face escalating ecological degradation due to anthropogenic pressures, particularly heavy metal contamination, posing unresolved risks to food safety and ecosystem integrity. This study investigated heavy metal accumulation in water chestnut (Trapa natans) across four major water bodies, i.e., Dal Lake, Hokersar Wetland, Manasbal Lake, and Wular Lake. Water, sediment, and plant tissues (root, shoot, fruit) were collected and analyzed for eight heavy metals (Cd, Cr, Cu, Co, Fe, Mn, Ni, Zn) using ICP–OES along with physicochemical profiling. Results indicated a distinct spatial gradient, with Dal Lake exhibiting the highest pollution load. Roots exhibited the highest heavy metal concentrations among plant tissues, with Fe (322.50 mg kg− 1) and Zn (82.45 mg kg− 1) showing the maximum levels, while Cd attained a maximum of 0.11 mg/kg in fruits. Bioconcentration factor values > 1 indicate that T. natans behaves as an effective metal accumulator, whereas translocation factors (TF < 1) classify the species as a moderate translocator with strong root retention capacity. The accumulation of nutrient element (ANE) model demonstrated Fe dominance (> 80%) in total elemental load. Although T. natans showed phytoremediation potential, heavy metal presence in edible tissues indicates potential trophic transfer risk. Overall, the study showed that contamination in Kashmir’s lentic systems directly influences heavy metal bioavailability in macrophytes, necessitating continuous biomonitoring.