Integrated assessment of phytotoxicity, stress responses, and bioaccumulative mechanisms of the arsenic-contaminated agricultural runoff using a soilless cultivation system

Abstract

The present study has been oriented to the integrated assessment of physical, chemical, and physicochemical characteristics of the agricultural runoff (AR). The physical growth vigor, physiological and morphological changes, oxidative stress biomarkers, enzymatic and non-enzymatic antioxidative responses, elemental profiles, and bioaccumulative pathway of okra plant in relation to the changing concentrations of AR-induced irrigation were evaluated using a soilless cultivation system. Lindane, endosulfan, heptachlor epoxide, methoxychlor, hexachlorobenzene, chlordane, aldrin, heptachlor, dichlorodiphenyl-trichloroethane, and dieldrin were predominantly detected within the concentration range of 0.0025–0.069 µg/L, while arsenic, boron, copper, iron, manganese, and zinc were found at 0.63–25.50 µg/L. Concentration-dependent alterations of macroscopic symptoms, chlorophylls, morphological structures, reactive oxygen species, lipid peroxidation, protein oxidation, antioxidant enzymes, total phenolic content, and radical scavenging potential were recorded in the AR-irrigated groups. The accumulation of heavy metals were found in a descending order of: root>shoot>leaf>fruit. Specifically, arsenic was identified as the critical polluting species, as evidenced by the drastic interference in the uptake and metabolism of phosphate, calcium, potassium, and magnesium. The tolerable threshold concentration of 60% AR could be applied as a renewable source of irrigation water, verified by the negligible phytotoxic implications in the plant model.