TITLE:
Major Ions in Atmospheric Deposition in Lake Kivu Basin
AUTHORS:
Mashimango Bagalwa, Jackson Gilbert Mwanjalolo Majaliwa, Katcho Karume, Sarah Akello, Frank Kansiime
KEYWORDS:
Dry and Wet Deposition, Major Ions, Lake Kivu
JOURNAL NAME:
Journal of Environmental Protection,
Vol.14 No.3,
March
22,
2023
ABSTRACT: This study investigated the major ion composition and sources in wet and dry deposition samples collected over 15 months (December 2017 to February 2019) at four stations representing four different land use/cover types on the western side of Lake Kivu basin in D.R. Congo. The samples were collected every 13 days for dry deposition and two to three times per month for wet deposition. Samples were analyzed for major ionic components (Cl-, NO-3, SO2-4, Na+, K+, NH+4, Ca2+, CO2-3, HCO-3 and Mg2+). Electrical conductivity and pH were analyzed immediately in the field while major ion measurements were in the laboratory. Results showed the pH of both the dry and the wet depositions were higher than what would have been expected based on equilibration with atmospheric CO2 (pH > 5.6) at all four sites, with conductivity less than 50 μS/cm. The neutralization process in dry and wet atmospheric deposition is due to Ca2+, NH+4, HCO-3 and CO2-3. The anion: cation ratio in dry deposition was close to 1 for Iko and Bukavu, and it was greater than 1.0 (1.1 - 1.2) for Lwiro and Goma in wet deposition. The dominant anions in wet deposition were SO2-4 and NO-3, found around the rural area near cement factory and the urban area near active volcanoes, respectively. The most abundant cation was Na+ followed by K+. The enrichment factors and correlation analysis suggest that the main sources of Ca2+, Na+ and Mg2+ were disintegration of soil processes, aeolian suspension of soil and volcanic ash, biomass burning and the cement/lime factory around the Lake Kivu basin.