PHYSICOCHEMICAL AND BIOLOGICAL ASSESSMENT OF SURFACE WATER QUALITY AND POLLUTANT DYNAMICS IN LAMURDE, ADAMAWA STATE, NIGERIA

This study assessed the physicochemical and biological quality of selected surface-water bodies in Lamurde, Adamawa State, Nigeria, focusing on spatial and seasonal variations and pollution risks. Water samples from upstream, midstream, and downstream during wet and dry seasons were analyzed for physical parameters, heavy metals, microbiological indicators, and aquatic communities. Water temperature ranged from 24.8–31.6°C; turbidity and conductivity from 12.5–78.3 NTU and 145–412 µS/cm. Higher temperatures and conductivity occurred in the dry season, while turbidity increased during the rainy season, especially downstream. The mean pH was 6.4 ± 0.5; dissolved oxygen ranged from 3.2–6.5 mg/L. Elevated BOD₅ (3.4–7.8 mg/L), COD (11.0–26.5 mg/L), nitrate (6.5–18.9 mg/L), and phosphate (1.1–4.3 mg/L) indicated organic and nutrient enrichment. Lead and cadmium exceeded guidelines at some sites; zinc remained within limits. Two-way ANOVA revealed significant spatial (F=8.42, p<0.01) and seasonal (F=6.73, p<0.05) differences across parameters. Microbiological tests showed increasing coliform counts from upstream to downstream, with E. coli in most samples. Biological assessment revealed declining plankton diversity and macroinvertebrates downstream, with pollution-tolerant taxa dominating. On the whole, physicochemical, microbiological, and biological indicators point to declining water quality, mainly from agriculture, domestic waste, poor sanitation, livestock, and human activities. The study recommends better pollution control, sanitation, continuous monitoring, and treatment before domestic use.