Open AccessPollution as a threat factor to urban food security in metropolitan K ano, N igeria
Author(s) -
Dawaki Mansur U.,
Dikko Abubakar U.,
Noma Samaila S.,
Aliyu Umar A.
Publication year - 2013
Publication title -
food and energy security
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.253
H-Index - 25
ISSN - 2048-3694
DOI - 10.1002/fes3.18
Subject(s) - wastewater , pollution , environmental science , environmental chemistry , irrigation , enrichment factor , contamination , environmental engineering , soil contamination , soil water , chemistry , heavy metals , agronomy , ecology , biology , soil science
This study evaluated the potentials of pollution due to urban agriculture to pose risk to food security in K ano, N igeria. Two sites irrigated with industrial and domestic wastewaters at C hallawa and J akara, respectively, were sampled for soil, water, and lettuce ( L actuca sativa L .). The samples were analyzed for Pb, Cd, Cr, and Cu being metals which when present in food may pose human health hazard. The values were compared with samples from a control site not associated with wastewater at W atari. The sites were each segmented into up, mid, and downstream sectors. Results showed that the two sites and the control were contaminated with Cu (pollution indexes [ PI ] = 0.14, 0.16, and 0.14, respectively). Domestic wastewater site was slightly polluted ( PI = 1.09) while industrial wastewater site and the control were contaminated ( PI = 0.8 and 0.54, respectively) with Pb. The two sites were excessively polluted with Cd and slightly polluted with Cr. The control was contaminated with both ( PI = 0.74 and 0.06 for Cd and Cr, respectively). Metal levels in the waters of the sites and the control were higher than the recommended threshold for irrigation water. There was significant positive correlation between Pb, Cr, and Cd in water and in soil; while Cu in soil and in water negatively correlated. There was high metal transfer from soil to plants at the domestic wastewater site (Metal transfer factor Pb = 1.602, Cr = 1.126, and Cu = 1.834). Plants' accumulated concentrations were also high at the domestic wastewater site (Pb = 26.21 mg/kg, Cd = 1.03 mg/kg, Cr = 28.63, and Cu = 2.66 mg/kg). The plants' metal concentrations at the domestic wastewater site exceeded the allowable limits in vegetables. The human ingestion risk was in the order of J akara > C hallawa > W atari.