Nitrogen and phosphorus in water and sediments at Ria Lagartos coastal lagoon, Yucatan, Gulf of Mexico (original) (raw)
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Se realizó un estudio en los sedimentos de la Laguna Chelem, situada en el litoral del Golfo de México, al norte de la Península de Yucatán (México), midiendo la concentración de nutrientes en el agua intersticial. El amonio tuvo un máximo de 1,045 PM, con valor medio de 459 k 281 PM; el nitrito alcanzó 5.3 PM, con valor medio de 1.8 f 1.8 PM; el nitrato se encontró en concentraciones de hasta 34.7 PM, con valor medio de 8.2 f 10.3 PM, y el fosfato presentó un máximo de 1 .l @vI, con valor medio de 0.4 f 0.4 PM. Usando la ecuación de la primera ley de Fick, se calculó el flujo de los nutrientes mencionados, a través de la interfase agua-sedimento. En todos ellos, el flujo promedio de las catorce muestras de la laguna fue del sedimento hacia el agua, siendo de 182 pmol/m*h para el amonio, 0.5 wol/m*h para el nitrito, 1.9 pmol/m* h para el nitrato y 0.03 pol/m*h para el fosfato. Con el fm de conocer las tasas de desnitrificación, se realizaron incubaciones de los sedimentos en condiciones anaeróbicas, con agua de la laguna enriquecida con nitrato. Este proceso se llevó a cabo activamente en cinco de las catorce estaciones muestreadas y la tasa mayor fue la de la estación 8, con 16.07 pmo l/m *h. La muestra de esta estación también presentó el contenido de materia orgánica más elevado (9.2%) y el mayor flujo de nitrato (del agua al sedimento). Las estimaciones de los flujos netos, con base en las áreas de cada una de las zonas de la Laguna Chelem, indicaron un importante aporte de los sedimentos hacia la columna de agua, de los cuatro nutrientes estudiados, sobre todo del amonio. ABSTRACT The sediments of Chelem Lagoon, on the coast of the Gulf of Mexico, north of the Yucatán Peninsula, were studied measuring the nutrient concentrations in the interstitial water. Ihe average values were: ammonium 459 f 281 PM, peaking up to 1,045 PM; nitrite 1.8 f 1.8 PM, with a maximum of 5.3 PM; nitrate 8.2 f 10.3 PM, reaching 34.7 PM, phosphate 0.4 f 0.4 PM, with a maximum of 1.1 PM. Fluxes were estimated with Fick's tirst law equation. In al1 cases, the mean flux of the 14 samples from the lagoon were from the sediment to the water column; these values were 183 umol/m'h for ammonium, 0.5 umoVm*h for nitrite, 1.9 umol/m*h for nitrate a.nd 0.03 umol/m*h for phosphate. In order to determine denitritication rates, incubations of the sedi-65 Al Contenido de este Número Ciencias A4urinas, Vol. 20, No. 1, 1994 ments were carried out under anaerobic conditions with water from the lagoon enriched with nitrate; denitrification was found to be active in tive of the 14 samples, with the highest rate in sample No. 8 (16.07 umol/m*h), which had the greatest content of organic matter (9.2%) and the highest nitrate flux (from the water to the sediment). The calculation of the net flux in the Chelem area showed an important supply from the sediment to the water column of the four nutrients studied, greatest in ammonium.
Estuarine, Coastal and Shelf Science, 2007
Nutrient inputs associated with coastal population growth threaten the integrity of coastal ecosystems around the globe. In order to assess the threat posed by rapid growth in tourism, we analyzed the nutrient concentrations as well as the d 15 N of NO 3 À and macrophytes to detect wastewater nitrogen (N) at 6 locations along a groundwater-dominated coastal seagrass bed on the Caribbean coast of Mexico. We predicted that locations with greater coastal development would have higher concentrations of dissolved inorganic nitrogen (DIN) and phosphorus (P), as well as d 15 N of NO 3 À , reflecting wastewater sources of N. However, concentrations of NO 3 À were not significantly different between developed (3.3 AE 5.3 mM NO 3 À ) and undeveloped (1.1 AE 0.7 mM) marine embayments. The most important control on DIN concentration appeared to be mixing of fresh and salt water, with DIN concentrations negatively correlated with salinity. The d 15 N of NO 3 À was elevated at an inland pond (7.0 AE 0.42&) and a hydrologically-connected tide pool (7.6 AE 0.57&) approximately 1 km downstream of the pond. The elevated d 15 N of NO 3 À at the pond was paralleled by high d 15 N values of Cladophora sp., a ubiquitous green alga (10 AE 1&). We hypothesize that inputs of nitrogen rich (NO 3 À > 30 mM) groundwater, characterized by 15 N enriched signatures, flow through localized submarine groundwater discharges (SGD) and contribute to the elevated d 15 N signatures observed in many benthic macrophytes. However, changes in nitrogen concentrations and isotope values over the salinity gradient suggest that other processes (e.g. denitrification) could also be contributing to the 15 N enrichments observed in primary producers. More measurements are needed to determine the relative importance of nitrogen transformation processes as a source of 15 N to groundwaters; however, it is clear that continued inputs of anthropogenic N via SGD have the potential to severely impact ecologically and economically valuable seagrass meadows and coral reefs along the Caribbean coast of Mexico.
Archives of Environmental Contamination and Toxicology, 2007
210 Pb-derived sediment accumulation rates, as well as a suite of geochemical proxies (Al, Fe, d 13 C, d 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 d 13 C suggested an estuarine system that is responsive to increased C loading from a N-limited phytoplankton community, whereas d 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.
Estuaries and Coasts, 2015
Direct measurements of net N 2 production, oxygen, and inorganic nutrient fluxes at the sediment-water interface were conducted in the San José Lagoon (SJL), a tropical coastal lagoon located at the San Juan Bay Estuary, Puerto Rico, that is heavily impacted by anthropogenic activities. Sediment of the SJL had high organic matter (average=16.7 %; SD= 9.0), pore water ammonium (541 μM±422), and pore water soluble reactive phosphorus (SRP) (57 μM±48) concentrations. High fluxes of oxygen (−1999 μmol m −2 h −1 ±2180) and N 2-N (192 μmol m −2 h −1 ±315) fluxes were observed. Similarly, high fluxes of ammonium (770 μmol m −2 h −1 ± 701) and SRP fluxes (167 μmol m −2 h −1 ±138) were measured, with moderate nitrate fluxes (−40 μmol m −2 h −1 ±53) mostly directed into the sediment. The dissolved inorganic nitrogen and soluble reactive phosphorus ratio (DIN/SRP) was low relative to the Redfield ratio and suggested that the sediment would support SJL as a nitrogen-limited system. An experiment with higher nitrate concentration resulted in a significant response (p<0.05) of denitrifying microbes and ammonium fluxes to a 100-μM KNO 3 addition. Net N 2 production was an important sink in the nitrogen balance of the SJL, though most remineralized N was released as ammonium. Efforts to mitigate eutrophication in the SJL require consideration of the substantial role that sediments play in biogeochemical cycles.
Acta Ecologica Sinica, 2017
Seventy-seven water samples were collected at the surface (S) and bottom (B) water profiles along eight transects (T1-T8) from Bahia Magdalena lagoon, Baja California Sur, Mexico during October 2014 to evaluate the spatial distribution patterns of dissolved inorganic nutrients (nitrates, nitrites and phosphates). Sea water properties (pH, temperature, dissolved oxygen, salinity, density and conductivity) were measured using a CTD instrument to assess their vertical profiling. On average, the lagoonal waters perceived raised temperatures (28.98°C) and salinities (35.2 PSU) due to its semi-arid environmental setting. The lagoon presented an average pH value of 8.25 due to the high influence of sea water under oxygenated conditions. Due to the impact of wind driven waves and ventilation process, high oxygen saturation value of 96.8% (avg.) was observed in the waters. The average inorganic nutrient levels in the lagoon (nitrites: 0.002 mg/L, nitrates: 0.033 mg/L, phosphates: 0.023 mg/L) is due to the distinctive biogeochemical lagoon processes namely reduced precipitation, upwelling and absence of river input. The present study provides a preliminary data on the hydrographical and nutrient characteristics of a highly productive lagoon on the western coastal margin (Mexico) of the Pacific Ocean.
Environmental Monitoring and Assessment, 2013
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2005
Mangrove ecosystems can significantly influence adjacent coastal areas by acting as either sources or sinks of organic carbon and nutrients. In this study, the total export of carbon and nitrogen from Celestun Lagoon, located on the Yucatan Peninsula, Mexico, was measured during two different seasons. The net export of dissolved and particulate carbon and nitrogen was calculated using measured concentrations within the lagoon coupled with hydrodynamic measurements of lagoon water exchange and published water budgets. The results show that Celestun Lagoon is a source of both organic carbon and nitrogen to the adjacent coastal ocean. Dissolved organic carbon accounted for 92% of the total carbon export, while the particulate form of organic nitrogen accounted for between 65-85% of the total nitrogen export. Groundwater is the major source of dissolved inorganic nitrogen to Celestun Lagoon, but is an insignificant source of both particulate and dissolved organic carbon. The majority of dissolved inorganic nitrogen from the groundwater is recycled within the lagoon, with only a small fraction (approximately 10%) exported to the coastal ocean. Due to the significant export of carbon and nitrogen from the lagoon to the coastal ocean, changes in lagoon functioning or groundwater composition, such as from pollution, will result in changes to the carbon and nitrogen budgets of the adjacent coastal ocean."