Ruiz-Fernández Ana Carolina, Frignani Mauro, Tesi Tommaso, Bojórquez-Leyva Humberto, Bellucci Luca Giorgio, Páez-Osuna Federico
Universidad Nacional Autónoma de México, Instituto de Ciencias del Mar y Limnología, Calz. J. Montes Camarena s/n, 82040, Mazatlan, México.
Arch Environ Contam Toxicol. 2007 Aug;53(2):159-67. doi: 10.1007/s00244-006-0122-3. Epub 2007 Jun 2.
(210)Pb-derived sediment accumulation rates, as well as a suite of geochemical proxies (Al, Fe, delta(13)C, delta(15)N), 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 delta(13)C suggested an estuarine system that is responsive to increased C loading from a N-limited phytoplankton community, whereas delta(15)N 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.
利用源自（210）铅的沉积物积累速率以及一系列地球化学指标（铝、铁、δ¹³C、δ¹⁵N），评估了在过去100年里从墨西哥加利福尼亚湾奥伊拉泻湖采集的两个沉积物岩芯中记录的碳、氮和磷通量随时间的变化。沉积物中的碳、氮和磷浓度随时间增加，且与土地开垦、蓄水以及施肥等农业活动有关。碳：氮：磷比率和δ¹³C表明该河口系统对来自氮限制浮游植物群落的碳负荷增加有响应，而δ¹⁵N值显示了由于1900年至1956年间埃尔富埃特河被改道和蓄水，河口淡水供应减少，导致河口从陆地 - 河口环境向河口 - 更海洋环境的转变。自20世纪40年代以来，大陆地区养分通量最近的增加（碳和氮的通量是人为活动前通量的2至9倍，磷的通量是2至13倍）与集约化农田的扩张以及最近虾类养殖活动的发展有关。
