Comparative Assessment of the Environmental Dynamics of Dissolved Organic Nitrogen (DON) and Dissolved Organic Phosphorus (DOP) from Three Wetlands in Northern Nigeria

Abstract

This study assessed comparatively the environmental dynamics of dissolved organic nitrogen (DON) and dissolved organic phosphorus (DOP) in water samples obtained from three locations (Lokoja, Jebba and Hadejia-Nguru) with five sampling sites in Northern Nigeria. These sites include Jebba, Matara-Uku, Lokoja, Baturiya and Nguru. Samples were collected during the dry and wet seasons of the year 2015 and levels of nitrogen and phosphorus determined using the persulphate wet-oxidation method. The average values for DON and DOP obtained ranged from 9.49±1.83 mg/l to 21.8±14.7 mg/l and 1.65±0.38 mg/l to 6.11±0.58 mg/l respectively. The values obtained for DON during the dry and wet seasons were Jebba (14.1±3.92), Matara-Uku (13.7±3.43), Lokoja (21.0±5.04), Baturiya (21.8±14.7), Nguru (7.14±2.40) and Jebba (13.9±1.97), Matara-Uku (11.3±2.62), Lokoja (9.59±1.46), Baturiya (9.49±1.83), Nguru (11.1±1.78) mg/l respectively. The mean values for DOP were Jebba (1.85±0.07), Matara-Uku (2.60±0.55), Lokoja (2.65±0.31), Baturiya (2.52±0.46), Nguru (1.65±0.38) and Jebba (3.70±0.16), Matara-Uku (5.55±0.24), Lokoja (6.11±0.58), Baturiya (4.93±0.90), Nguru (3.65±0.37) mg/l in the dry and wet seasons respectively. The DON concentrations were significantly higher (p<0.05) in the dry season when compared with the wet season while the DOP concentrations were significantly higher (p<0.05) in the wet season when compared with the dry season. This dynamics was attributed to run off from agricultural farm lands, hydrology and the rate of utilization of these nutrients by water plants. High concentrations of DOP and DON supportgood yield of agricultural produce of the farmlands around the wetlands.

Keywords: Dissolved organic nitrogen, dissolved organic phosphorus, dissolved organic matter, wetlands