Article

Archives of Environmental Contamination and Toxicology

, Volume 53, Issue 2, pp 159-167

First online:

Recent Sedimentary History of Organic Matter and Nutrient Accumulation in the Ohuira Lagoon, Northwestern Mexico

  • Ana Carolina Ruiz-FernándezAffiliated withUniversidad Nacional Autónoma de México, Instituto de Ciencias del Mar y Limnología Email author 
  • , Mauro FrignaniAffiliated withIstituto di Scienze Marine, CNR
  • , Tommaso TesiAffiliated withIstituto di Scienze Marine, CNR
  • , Humberto Bojórquez-LeyvaAffiliated withUniversidad Nacional Autónoma de México, Instituto de Ciencias del Mar y Limnología
  • , Luca Giorgio BellucciAffiliated withIstituto di Scienze Marine, CNR
  • , Federico Páez-OsunaAffiliated withUniversidad Nacional Autónoma de México, Instituto de Ciencias del Mar y LimnologíaEl Colegio de Sinaloa

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Abstract

210Pb-derived sediment accumulation rates, as well as a suite of geochemical proxies (Al, Fe, δ13C, δ15N), were used to assess the time-dependent variations of C, N, and P fluxes recorded in two sediment cores collected at Ohuira Lagoon, in the Gulf of California, Mexico, during the last 100 years. Sedimentary C, N, and P concentrations increased with time and were related to land clearing, water impoundment, and agriculture practices, such as fertilization. C:N:P ratios and δ13C suggested an estuarine system that is responsive to increased C loading from a N-limited phytoplankton community, whereas δ15N values showed the transition between an estuarine-terrestrial to an estuarine-more marine environment, as a consequence of the declining freshwater supply into the estuary due to the channeling and impoundment of El Fuerte River between 1900 and 1956. The recent increases in nutrient fluxes (2- to 9-fold the pre-anthropogenic fluxes of C and N, and 2 to 13 times for P) taking place in the mainland from the 1940s, were related to the expansion of the intensive agriculture fields and to the more recent development of shrimp farming activities.