Adina Paytan | University of California, Santa Cruz (original) (raw)

Papers by Adina Paytan

AGU Fall Meeting Abstracts, Dec 1, 2003

Abstract Tropical and sub-tropical wetlands are thought to be the dominant natural source of meth... more Abstract Tropical and sub-tropical wetlands are thought to be the dominant natural source of methane to the atmosphere, and the majority of tropical methane flux research has been carried out in freshwater environments. In order to obtain better estimates of methane emissions from tropical coastal environments, we are currently conducting a multi-year study of methane cycling and flux in three tropical coastal lagoons and associated mangrove ecosystems located on the Yucatan Peninsula in Mexico. Previous studies have shown ...

AGU Fall Meeting Abstracts, Dec 1, 2004

Abstract Phosphorous is an essential macro-nutrient for primary productivity, but tracing sources... more Abstract Phosphorous is an essential macro-nutrient for primary productivity, but tracing sources and cycling of P in marine systems has been difficult to assess because P has only one stable isotope and can not be used as an isotopic tracer. Recently a new technique (McLaughlin et al., 2004) has been developed to track sources and cycling of phosphate in aquatic systems. This approach takes advantage of the strong PO bond in phosphate, which is resistant to inorganic hydrolysis. The exchange of oxygen isotopes therein only occurs ...

AGU Fall Meeting Abstracts, Dec 1, 2006

Abstract Phosphorous (P) is an essential macronutrient in aquatic ecosystems and eutrophication d... more Abstract Phosphorous (P) is an essential macronutrient in aquatic ecosystems and eutrophication due to anthropogenic inputs of phosphorous has been observed in many places throughout the world. Although P has only one stable isotope, advances in stable isotope mass spectrometry have made it possible to analyze the isotopic composition of the oxygen atoms bound to the P in both dissolved inorganic phosphate and in various organic phosphorus containing compounds including particulate organic matter. The oxygen ...

AGUFM, Dec 1, 2010

Abstract Submarine groundwater discharge (SGD) is a major pathway for the delivery of fresh water... more Abstract Submarine groundwater discharge (SGD) is a major pathway for the delivery of fresh water, nutrients, and pollutants to the coastal ocean, but few studies have attempted to reconstruct past groundwater fluxes to the coast, or examined the relationship between SGD and regional climate change over long timescales. Here we present a new record of paleo-groundwater input to Celestun Estuary, on the northwestern coast of the Yucatan Peninsula, based on the strontium isotope composition (87Sr/86Sr) of benthic foraminifera separated ...

AGUFM, Dec 1, 2003

We present a 2-yr time series of the oxygen isotopic composition of dissolved inorganic phosphate... more We present a 2-yr time series of the oxygen isotopic composition of dissolved inorganic phosphate (d 18 O p) in Monterey Bay, California. d 18 O p can serve as a proxy for phosphate utilization because its approach toward isotopic equilibrium is a function of the degree of biological phosphate cycling. When phosphate is extensively cycled by the biological community in the euphotic zone, the d 18 O p approaches isotopic equilibrium with surrounding water. Our results indicate that d 18 O p in the upper water column is consistently out of isotopic equilibrium with respect to seawater and fluctuates between the equilibrium value and the isotopic signatures of phosphate sources. This suggests that either phosphate is not extensively utilized or that the input of new phosphate to the bay exceeds the requirements of the biological community. d 18 O p is variable and linked to episodic upwelling events and the biotic response to these events. The greatest percent of phosphate oxygen exchange, and thus the greatest phosphate utilization relative to input, occurs at the locus of upwelling (Sta. M1), followed by the offshore (M2) and nearshore (C1) stations, respectively. During the highly productive upwelling season, phosphate turnover is greater than in the winter. Episodes of higher phosphate turnover, as indicated by peaks in d 18 O p , occur simultaneously throughout the upper 200 m of the water column and at all three stations, indicating that these events affect the bay on a large scale. d 18 O p data also suggest that deep water (.500 m) may be a source of phosphate to the euphotic zone in Monterey Bay.

Marine Chemistry, Feb 1, 2006

The phosphate oxygen isotopic composition in naturally occurring particulate phosphatic compounds... more The phosphate oxygen isotopic composition in naturally occurring particulate phosphatic compounds (y 18 O p) can be used as a tracer for phosphate sources and to evaluate the cycling of phosphorus (P) in the environment. However, phosphatic compounds must be converted to silver phosphate prior to isotopic analysis, a process that involves digestion of particulate matter in acid. This digestion will hydrolyze some of the phosphatic compounds such that oxygen from the acid solution will be incorporated into the sample as these phosphatic compounds are converted to orthophosphate (PO 4 3À). To determine the extent of incorporation of reagent oxygen into the sample, we digested various phosphatic compounds in both acid amended with H 2 18 O (spiked) and unspiked acid and then converted the samples to silver phosphate for y 18 O p analysis. Our results indicate that there is no isotopic fractionation associated with acid digestion at 50 8C. Furthermore, we found that reagent oxygen incorporation is a function of the oxygen to phosphorus ratio (O:P) of the digested compound whereby the percentage of reagent oxygen incorporated into the sample is the same as that which is required to convert all of the P-compounds into orthophosphate. Based on these results, we developed a correction for reagent oxygen incorporation using simple mass balance, a procedure that allows for the determination of the y 18 O p of samples containing a mixture of phosphatic compounds. We analyzed a variety of environmental samples for y 18 O p to demonstrate the utility of this approach for understanding sources and cycling of P.

Spatial patterns of marine Synechococcus diversity across ocean domains have been reported on ext... more Spatial patterns of marine Synechococcus diversity across ocean domains have been reported on extensively. However, much less is known of seasonal and multiannual patterns of change in Synechococcus community composition. Here we report on the genotypic diversity of Synechococcus populations in the Gulf of Aqaba, Northern Red Sea, over seven annual cycles of deep mixing and stabile stratification, using ntcA as a phylogenetic marker. Synechococcus clone libraries were dominated by clade II and XII genotypes and a total of eight different clades were identified. Inclusion of ntcA sequences from the Global Ocean Sampling database in our analyses identified members of clade XII from beyond the Gulf of Aqaba, extending its known distribution. Most of the Synechococcus diversity was attributed to members of clade II during the spring bloom, while clade III contributed significantly to diversity during summer stratification. Clade XII diversity was most prevalent in fall and winter. Clade abundances were estimated from pyrosequencing of the V6 hypervariable region of 16S rRNA. Members of clade II dominated Synechococcus communities throughout the year, whereas the less frequent genotypes showed a pattern of seasonal succession. Based on the prevailing nutritional conditions we observed that clade I members thrive at higher nutrient concentrations during winter mixing. Clades V, VI and X became apparent during the transition periods between mixing and stratification. Clade III became prominent during sumeer stratification. We propose that members of clades V, VI, and X, and clade III are Synechococcus ecotypes that are adapted to intermediate and low nutrient levels respectively. This is the first time that molecular analyses have correlated population dynamics of Synechococcus genotypes with temporal fluctuations in nutrient regimes. Since these Synechococcus genotypes are routinely observed in the Gulf of Aqaba we suggest that seasonal fluctuations in nutrient levels create temporal niches that sustain their coexistence.

Estuaries and Coasts, Jun 28, 2012

Nature, Dec 1, 1993

THE strontium isotope ratio in sea water is influenced by climate, tectonics, weathering and hydr... more THE strontium isotope ratio in sea water is influenced by climate, tectonics, weathering and hydrothermal activity at ocean ridges 1��4. Its evolution through time, determined primarily by measuring the strontium isotope composition of marine carbonates, holds information about variations in these processes, and is also useful for stratigraphic correlation and dating 5��7. Carbonates are absent from some marine sediments such as siliceous oozes and red clays, and can be significantly diagenetically altered in others, especially in Eocene and older ...

Proceedings of the National Academy of Sciences of the United States of America, Mar 9, 2015

Marine Chemistry, Jun 1, 2003

Geology, 2002

Barite can precipitate in microenvironments in the water column (marine barite), from supersatura... more Barite can precipitate in microenvironments in the water column (marine barite), from supersaturated pore fluids at the oxic-anoxic boundary within marine sediments and where Ba-rich pore fluids are expelled and come into contact with sulfate-rich seawater (diagenetic barite), or from hydrothermal solutions (hydrothermal barite). Barite is relatively resistant to alteration after burial and has been used in paleoceanographic studies to reconstruct seawater chemistry and productivity through time. For such applications it is very important to determine the origin of the barite used, because both diagenetic and hydrothermal barite deposits may not accurately record the open-ocean contemporaneous seawater chemistry and productivity. We show here that it is possible to distinguish between the different types of barite by using Sr and S isotopes along with crystal morphology and size characteristics.

AGUFM, Dec 1, 2001

Abstract Marine barite may serve as a proxy to reconstruct past export production (Dymond, 1992).... more Abstract Marine barite may serve as a proxy to reconstruct past export production (Dymond, 1992). In most studies sedimentary barite accumulation is not measured directly, instead a parameter termed excess barium (Baexs), also referred to as biogenic barium, is used to estimate the barite content. Baexs is defined as the total Ba concentration in the sediment minus the Ba associated with terrigenous material. Baexs is calculated by normalization to a constant Ba/Al ratio, typically the average shale ratio. This application assumes that (1) all ...

AGU Fall Meeting Abstracts, Dec 1, 2009

Abstract Multiple studies have attempted to reconstruct Quaternary climate variability in Meso-Am... more Abstract Multiple studies have attempted to reconstruct Quaternary climate variability in Meso-America and the Caribbean region conditions may drive climate on a global scale and by the realization that the region is well-placed to track past shifts in the average position of the Intertropical Convergence Zone (ITCZ), which is a major control on precipitation and drought occurrence in tropical and sub-tropical areas of the world. With this in mind, we seek to develop a new record of late Holocene paleosalinity, freshwater input and ...

AGU Fall Meeting Abstracts, Dec 1, 2012

AGU Fall Meeting Abstracts, Dec 16, 2014