COMPARATIVE ANALYSIS OF HYDROGEOCHEMISTRY IN WET AND DRY SEASONS IN LAGOS STATE

This study investigates hydrogeochemical variability and health risks associated with groundwater quality across five distinct land-use zones in Lagos State, Nigeria. A total of 25 groundwater samples were collected following strict sampling protocols, representing residential, industrial, commercial, agricultural, and dumpsite areas. The samples were analyzed for physicochemical parameters in situ, while trace metals were determined in the laboratory using inductively coupled plasma mass spectrometry (ICP-MS) and inductively coupled plasma-optical emission spectrometry (ICP-OES). Measured physicochemical parameters showed variations with pH ranging from 5.13±0.46 to 7.10±0.16, electrical conductivity (EC) from 114.28±14.11 to 303.62±92.67 µS/cm, salinity from 0.01±0.00 to 0.10±0.04 ppt, total dissolved solids (TDS) from 42.25±4.55 to 131.05±40.29 mg/L, and temperature from 26.06±0.31°C to 26.28±0.11°C. Heavy metals such as arsenic (As), cadmium (Cd), chromium (Cr), copper (Cu), nickel (Ni), lead (Pb), and mercury (Hg), among others, were detected in varying concentrations. Notably, elevated levels of lead (up to 0.22±0.21 mg/L), arsenic (up to 0.04±0.00 mg/L), and nickel (up to 0.03±0.02 mg/L) were found, particularly in samples from dumpsites and agricultural areas. These elevated concentrations are attributed to leachate from waste deposits and agrochemical usage.