Use of dye industry effluent for irrigation in Amaranthus cruentus L. production: effect on growth, root morphology, heavy metal accumulation, and the safety concerns

Abstract

This study characterized three local dye effluents from major tie and dye industries at Asero, Itoku, and Kemta in Ogun State, Nigeria, and evaluated their effect on growth and heavy metal accumulation in pot-grown amaranth. The effluents were diluted with water at 0%, 25%, 50%, and 100% and replicated three times. Physicochemical properties and heavy metal content of effluent dilutions were analyzed. Results indicated that irrespective of the source, effluents, and dilutions, effluent properties exceeded permissible limits by World Health Organization/Food and Agricultural Organization/Federal Environmental Protection Agency for irrigation. The SO₄²⁻, PO₄³⁻, NO₃⁻, Fe, and Cr contents of effluent dilutions were higher than the maximum limits recommended. The order of toxicity of dye effluents was Asero > Itoku > Kemta. Effluent concentrations at 50% and 100% damaged amaranth root hairs, caused the death of some amaranth, significantly reduced number of leaves, height, fresh and dry root, and shoot weight, but increased stem girth and heavy metal accumulation in plant parts. Mg, Cu, and Zn were more concentrated in the shoots. Due to the high metal content, consumption of this vegetable poses a potential health risk. Strict law enforcement against the use of the effluent for irrigation should be made to prevent environmental hazard.

Keywords:

• amaranth
• dye effluents
• health risks
• metal accumulation

Acknowledgement

The efforts of Dr. O.S. Sakariyawo, Dr. M.A. Busari, and Dr. G.A. Ajiboye in improving the readability of this manuscript are gratefully acknowledged.