INFLUENCE OF HEAVY METALS CONTAMINATED INDUSTRIAL WASTEWATER ON IRRIGATION WATER AND LETTUCE (LECTUCA SATIVA) QUALITY IN KANO SUDAN SAVANNAH ZONE OF NIGERIA

Abstract

The aim of this study is to assess if discharged industrial wastewater containing heavy metals (HMs) from different industries of Gunduwawa industrial area in Kano and used for lettuce irrigation affect the quality of the irrigation water and the irrigated lettuce using international regulatory agencies standard. Water and lettuce samples were collected from three industrial locations and evaluated for quality using (HMs) under standard laboratory procedures. Findings indicated that out of the analysed metals; Lead (Pb), Nickel (Ni), Zinc (Zn) and Cadmium (Cd), only Cd and other irrigation water quality parameters; Chemical oxygen demand (COD), Nitrate-nitrogen (NO3-N), and Ammonia nitrogen (NH4-N) were non-compliant to standard of metals quality in the former and irrigation water quality in the latter and has recorded a significant difference (P<0.05) except for Ni that did not (P>0.05). Furthermore, COD and NO3-N showed significant difference (P<0.05) in location I compared to other locations, NH4-N in location II in comparison to locations I and III. Though pH complied with irrigation water quality standard, a highly significant difference (P<0.05) was noted in location II if compared with other locations. Overall, this indicates poor quality irrigation water for lettuce production and can potentially exert mutagenic and carcinogenic effects to the grown vegetables. Pertaining lettuce quality, results showed that the lettuce was contaminated with Cd metal and exceeded the standard limit for safety of food consumption.