Sedimentary record of water column trophic conditions and sediment carbon fluxes in a tropical water reservoir (Valle de Bravo, Mexico)

• Published in: Environmental science and pollution research international Vol. 22; no. 6; pp. 4680 - 4694
• Main Authors: Carnero-Bravo, Vladislav, Merino-Ibarra, Martín, Ruiz-Fernández, Ana Carolina, Sanchez-Cabeza, Joan Albert, Ghaleb, Bassam
• Format: Journal Article
• Language: English
• Published: Berlin/Heidelberg Springer-Verlag 01.03.2015; Springer Berlin Heidelberg; Springer Nature B.V
• Subjects: Aquatic ecosystems; Aquatic Pollution; Archives & records; Atmospheric Protection/Air Quality Control/Air Pollution; Biofilms; Carbon; Carbon - analysis; Carbon Cycle; Cesium radioisotopes; Cities; Cores; Cyanobacteria; Dam construction; Dams; Drinking water; Earth and Environmental Science; Ecosystem; Ecotoxicology; Environment; Environmental Chemistry; Environmental Health; Environmental impact; Environmental Monitoring; Eutrophic environments; Eutrophication; Evolution; Fresh Water - chemistry; Freshwater ecosystems; Freshwater environments; Geologic Sediments - analysis; Geologic Sediments - chemistry; Metropolitan areas; Mexico; nitrogen content; Nutrient concentrations; Organic carbon; Pesticide toxicity; Pesticides; radiometry; Research Article; Reservoirs; Rivers; Sea level; Sediments; soil; Total organic carbon; Toxicity; Waste Water Technology; Water column; Water Management; Water Pollutants, Chemical - analysis; Water Pollution Control; Water quality; water reservoirs; Water shortages; Water supply; Mexico; Mexico, Distrito Federal, Mexico City; Lake sediments; Pb chronology; Valle de Bravo reservoir; Eutrophication; Organic carbon fluxes
• ISSN: 0944-1344; 1614-7499
• DOI: 10.1007/s11356-014-3703-0

Valle de Bravo (VB) is the main water reservoir of the Cutzamala hydraulic system, which provides 40 % of the drinking water consumed in the Mexico City Metropolitan Area and exhibits symptoms of eutrophication. Nutrient (C, N and P) concentrations were determined in two sediment cores to reconstruct the water column trophic evolution of the reservoir and C fluxes since its creation in 1947. Radiometric methods (²¹⁰Pb and¹³⁷Cs) were used to obtain sediment chronologies, using the presence of pre-reservoir soil layers in one of the cores as an independent chronological marker. Mass accumulation rates ranged from 0.12 to 0.56 g cm⁻²year⁻¹and total organic carbon (TOC) fluxes from 122 to 380 g m⁻² year⁻¹. Total N ranged 4.9–48 g m⁻² year⁻¹, and total P 0.6–4.2 g m⁻² year⁻¹. The sedimentary record shows that all three (C, N and P) fluxes increased significantly after 1991, in good agreement with the assessed trophic evolution of VB and with historic and recent real-time measurements. In the recent years (1992–2006), the TOC flux to the bottom of VB (average 250 g m⁻² year⁻¹, peaks 323 g m⁻² year⁻¹) is similar to that found in highly eutrophic reservoirs and impoundments. Over 1/3 of the total C burial since dam construction, circa 70,000 t, has occurred in this recent period. These results highlight the usefulness of the reconstruction of carbon and nutrient fluxes from the sedimentary record to assess carbon burial and its temporal evolution in freshwater ecosystems.