An assessment of the organic pollution indicator levels of River Benue in Adamawa State, Nigeria

The assessment of organic pollution Indicator levels of River Benue in Adamawa State was carried in  ten sampling stations. The sampling was done in the months of February, March, and April 2007,  representing dry season, while the months of August, September, and October 2007, represent the wet  season. The water and sediment samples collected were analysed using standard procedures. The  pollution indicators determined includes: Dissolve oxygen (DO), biochemical oxygen demand (BOD5),  chemical oxygen demand (COD), and total organic carbon (TOC). The results for River Benue showed  the following concentrations of the parameters assessed: The BOD5 values ranged between 1.55 ± 0.68  and 3.72 ± 0.51 mg/l for dry season and 0.89 ± 0.11 and 1.70 ± 0.72 mg/l for wet season indicating that  values were higher during dry season than wet season. Likewise the COD values were between 2.97 ±  0.47 and 3.57 ± 0.97 mg/l for dry season and 2.49 ± 0.47 and 2.90±0.31 mg/l for wet season. This shows  high COD values during dry season than wet season. The TOC values ranged between 1.01 ± 0.06 and  1.52 ± 0.16% for dry season and 0.35 ± 0.06 and 0.56 ± 0.08% for wet season, while the DO values were  between 5.27 and 6.41 mg/l for dry season and 6.32 and 8.32 mg/l for wet season. This showed that the  DO was high during wet season than dry season. The BOD5, COD and TOC were high during dry  season, while the DO was low and vice versa. The correlation between BOD5 versus COD gave a  positive correlation of 0.652 and that of COD against TOC gave a positive correlation of 0.743 because  all of them are products of oxidation.  The correlation of DO against BOD5 gave a negative correlation of  0.693. The values of the organic indicators studied were within the allowable limits of WHO and  NAFDAC.    Key words: Organic indicators, pollution, River Benue, parameters, sediment, assessment