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Rogers MC, Heintz RA, Vollenweider JJ, Sreenivasan A, Miller KB. Climate change-informed dietary modeling in Pacific cod: Experimentally-derived effects of temperature and dietary quality on carbon and nitrogen stable isotope trophic discrimination factors. PLoS One 2023; 18:e0295564. [PMID: 38060595 PMCID: PMC10703269 DOI: 10.1371/journal.pone.0295564] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2023] [Accepted: 11/22/2023] [Indexed: 12/18/2023] Open
Abstract
Stable isotope analysis is a powerful tool for dietary modeling and trophic ecology research. A crucial piece of information for isotopic dietary modeling is the accurate estimation of trophic discrimination factors (TDFs), or the isotopic offset between a consumer's tissue and its diet. In order to parameterize stable isotope dietary models for future climate scenarios, we investigated the effect of water temperature and dietary protein and lipid content on TDFs in juvenile Pacific cod (Gadus macrocephalus). Pacific cod are a commercially and ecologically important species, with stock numbers in the northeast Pacific recently having dropped by more than 70%. We tested four water temperatures (6, 8, 10, and 12°C) and two dietary regimens (low and high lipid content), representing a range of potential ocean temperature and prey quality scenarios, in order to determine carbon and nitrogen TDFs in juvenile Pacific cod. Additionally, we assessed dietary intake and proximate composition of the experimental fish in order to estimate consumption, assimilation, and retention of dietary nutrients. The results of this study suggest that dietary protein catabolism is a primary driver of nitrogen TDF variability in juvenile Pacific cod. Across all temperature treatments from 6 to 12°C, fish reared on the lower quality, lower lipid content diet had higher nitrogen TDFs. The mean TDFs for fish raised on the higher lipid, lower protein diet were +3.40 ‰ for nitrogen (Δ15N) and +0.36 ‰ for lipid-corrected carbon (Δ LC 13C). The mean TDFs for fish raised on the lower lipid, higher protein diet were +4.09 ‰ for nitrogen (Δ15N) and 0.00 ‰ for lipid-corrected carbon (Δ LC 13C). Lipid-corrected carbon isotope data showed that, regardless of temperature, fish consuming the lower lipid diet had essentially no trophic discrimination between diet and bulk tissues. We found no ecologically meaningful differences in TDFs due to water temperature across the 6°experimental range. The results of this experiment demonstrate that dietary quality, and more specifically the use of dietary protein for energetic needs, is a primary driver of trophic discrimination factors. The TDFs determined in this study can be applied to understanding trophic ecology in Pacific cod and closely related species under rapidly changing prey availability and ocean temperature conditions.
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Affiliation(s)
- Matthew C. Rogers
- NOAA, National Marine Fisheries Service, Alaska Fisheries Science Center, Auke Bay Laboratories, Juneau, Alaska, United States of America
| | - Ron A. Heintz
- Sitka Sound Science Center, Sitka, Alaska, United States of America
| | - Johanna J. Vollenweider
- NOAA, National Marine Fisheries Service, Alaska Fisheries Science Center, Auke Bay Laboratories, Juneau, Alaska, United States of America
| | - Ashwin Sreenivasan
- University of Alaska Southeast, Juneau, Alaska, United States of America
| | - Katharine B. Miller
- NOAA, National Marine Fisheries Service, Alaska Fisheries Science Center, Auke Bay Laboratories, Juneau, Alaska, United States of America
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Chenoweth EM, Boswell KM, Friedlaender AS, McPhee MV, Burrows JA, Heintz RA, Straley JM. Confronting assumptions about prey selection by lunge‐feeding whales using a process‐based model. Funct Ecol 2021. [DOI: 10.1111/1365-2435.13852] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Ellen M. Chenoweth
- University of Alaska Fairbanks Fairbanks AK USA
- University of Alaska Southeast Sitka AK USA
| | | | - Ari S. Friedlaender
- University of California Santa Cruz Santa Cruz CA USA
- Oregon State University Newport OR USA
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Barron MG, Vivian DN, Heintz RA, Yim UH. Long-Term Ecological Impacts from Oil Spills: Comparison of Exxon Valdez, Hebei Spirit, and Deepwater Horizon. Environ Sci Technol 2020; 54:6456-6467. [PMID: 32267150 PMCID: PMC7397809 DOI: 10.1021/acs.est.9b05020] [Citation(s) in RCA: 52] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
Abstract
The long-term ecological impacts of the Exxon Valdez oil spill (EVOS) are compared to two extensively studied and more recent large spills: Deepwater Horizon (DWH) and the Hebei Spirit oil spill (HSOS). Each of the three spills differed in magnitude and duration of oil released, environmental conditions, ecological communities, response and clean up measures, and ecological recovery. The EVOS began on March 24, 1989, and released 40.8 million liters of Alaska North Slope crude oil into the cold, nearly pristine environment of Prince William Sound, Alaska. EVOS oiled wildlife and rocky intertidal shorelines and exposed early life stages of fish to embryotoxic levels of polycyclic aromatic hydrocarbons (PAH). Long-term impacts following EVOS were observed on seabirds, sea otters, killer whales, and subtidal communities. The DWH spill began on April 20, 2010, and released 507 million liters of light Louisiana crude oil from 1600 m on the ocean floor into the Gulf of Mexico over an 87-day period. The DWH spill exposed a diversity of complex aquatic communities in the deep ocean, offshore pelagic areas, and coastal environments to petroleum hydrocarbons. Large-scale persistent ecological effects included impacts to deep ocean corals, failed recruitment of oysters over multiple years, damage to coastal wetlands, and reduced dolphin, sea turtle, and seabird populations. The HSOS began on December 7, 2007, and released approximately 13 million liters of Middle East crude oils into ecologically sensitive areas of the Taean area of western Korea. Environmental conditions and the extensive initial cleanup of HSOS oil stranded on shorelines limited the long-term impacts to changes in composition and abundance of intertidal benthic communities. Comparisons of EVOS, DWH, and HSOS show the importance and complexity of the interactions among the environment, oil spill dynamics, affected ecological systems, and response actions.
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Affiliation(s)
- Mace G. Barron
- U.S. EPA, Office of Research and Development, Gulf Breeze, FL USA
| | | | | | - Un Hyuk Yim
- Korea Institute of Science and Technology, Geoje, Republic of Korea
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Barton MB, Moran JR, Vollenweider JJ, Heintz RA, Boswell KM. Erratum to: Latitudinal dependence of body condition, growth rate, and stable isotopes of juvenile capelin (Mallotus villosus) in the Bering and Chukchi Seas. Polar Biol 2017. [DOI: 10.1007/s00300-017-2097-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
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Siddon EC, Kristiansen T, Mueter FJ, Holsman KK, Heintz RA, Farley EV. Spatial match-mismatch between juvenile fish and prey provides a mechanism for recruitment variability across contrasting climate conditions in the eastern Bering Sea. PLoS One 2013; 8:e84526. [PMID: 24391963 PMCID: PMC3877275 DOI: 10.1371/journal.pone.0084526] [Citation(s) in RCA: 52] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2013] [Accepted: 11/15/2013] [Indexed: 12/02/2022] Open
Abstract
Understanding mechanisms behind variability in early life survival of marine fishes through modeling efforts can improve predictive capabilities for recruitment success under changing climate conditions. Walleye pollock (Theragra chalcogramma) support the largest single-species commercial fishery in the United States and represent an ecologically important component of the Bering Sea ecosystem. Variability in walleye pollock growth and survival is structured in part by climate-driven bottom-up control of zooplankton composition. We used two modeling approaches, informed by observations, to understand the roles of prey quality, prey composition, and water temperature on juvenile walleye pollock growth: (1) a bioenergetics model that included local predator and prey energy densities, and (2) an individual-based model that included a mechanistic feeding component dependent on larval development and behavior, local prey densities and size, and physical oceanographic conditions. Prey composition in late-summer shifted from predominantly smaller copepod species in the warmer 2005 season to larger species in the cooler 2010 season, reflecting differences in zooplankton composition between years. In 2010, the main prey of juvenile walleye pollock were more abundant, had greater biomass, and higher mean energy density, resulting in better growth conditions. Moreover, spatial patterns in prey composition and water temperature lead to areas of enhanced growth, or growth 'hot spots', for juvenile walleye pollock and survival may be enhanced when fish overlap with these areas. This study provides evidence that a spatial mismatch between juvenile walleye pollock and growth 'hot spots' in 2005 contributed to poor recruitment while a higher degree of overlap in 2010 resulted in improved recruitment. Our results indicate that climate-driven changes in prey quality and composition can impact growth of juvenile walleye pollock, potentially severely affecting recruitment variability.
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Affiliation(s)
- Elizabeth Calvert Siddon
- School of Fisheries and Ocean Sciences, University of Alaska Fairbanks, Juneau, Alaska, United States of America
| | | | - Franz J. Mueter
- School of Fisheries and Ocean Sciences, University of Alaska Fairbanks, Juneau, Alaska, United States of America
| | - Kirstin K. Holsman
- Joint Institute for the Study of the Atmosphere and Ocean, University of Washington, Alaska Fisheries Science Center, National Marine Fisheries Service, National Oceanic and Atmospheric Administration, Seattle, Washington, United States of America
| | - Ron A. Heintz
- Ted Stevens Marine Research Institute, Alaska Fisheries Science Center, National Marine Fisheries Service, National Oceanic and Atmospheric Administration, Juneau, Alaska, United States of America
| | - Edward V. Farley
- Ted Stevens Marine Research Institute, Alaska Fisheries Science Center, National Marine Fisheries Service, National Oceanic and Atmospheric Administration, Juneau, Alaska, United States of America
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Rinella DJ, Wipfli MS, Walker CM, Stricker CA, Heintz RA. Seasonal persistence of marine-derived nutrients in south-central Alaskan salmon streams. Ecosphere 2013. [DOI: 10.1890/es13-00112.1] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
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Vollenweider JJ, Heintz RA, Schaufler L, Bradshaw R. Seasonal cycles in whole-body proximate composition and energy content of forage fish vary with water depth. Mar Biol 2010; 158:413-427. [PMID: 24391256 PMCID: PMC3873054 DOI: 10.1007/s00227-010-1569-3] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/22/2010] [Accepted: 10/19/2010] [Indexed: 05/29/2023]
Abstract
Quantifying the nutritional quality of forage fish is integral for understanding upper trophic levels as forage fish are the dominant prey for top predator fish, marine mammals, and sea birds. Many existing reports documenting body composition of forage species are not comparable due to confounding effects. This study systematically assessed the variability in proximate composition and energy content of 16 forage species in southeastern Alaska (57.2626 N/133.7394 W) between 2001 and 2004. Variation in energy and lipid contents was related to habitat, epipelagic planktivores varying most, mesopelagics intermediate, and demersal species relatively invariable. Season was the greatest source of variation as a result of short growing seasons at high latitude and energy allocation strategies for reproduction and growth. Among species that varied seasonally, energy and lipid increased over summer and declined during winter. Annual differences in body composition occurred during periods of peak energy content. Sampling recommendations and guidance for bioenergetics models are provided.
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Affiliation(s)
- Johanna J. Vollenweider
- Alaska Fisheries Science Center, Ted Stephens Marine Research Institute, Auke Bay Laboratories, 17109 Point Lena Loop Road, Juneau, AK 99801 USA
| | - Ron A. Heintz
- Alaska Fisheries Science Center, Ted Stephens Marine Research Institute, Auke Bay Laboratories, 17109 Point Lena Loop Road, Juneau, AK 99801 USA
| | - Lawrence Schaufler
- Alaska Fisheries Science Center, Ted Stephens Marine Research Institute, Auke Bay Laboratories, 17109 Point Lena Loop Road, Juneau, AK 99801 USA
| | - Robert Bradshaw
- Alaska Fisheries Science Center, Ted Stephens Marine Research Institute, Auke Bay Laboratories, 17109 Point Lena Loop Road, Juneau, AK 99801 USA
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Heintz RA, Short JW, Rice SD, Carls MG. Comment on "Toxicity of weathered Exxon Valdez crude oil to pink salmon embryos". Environ Toxicol Chem 2008; 27:1475-1478. [PMID: 18260694 DOI: 10.1897/07-236] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/30/2007] [Accepted: 02/06/2008] [Indexed: 05/25/2023]
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Abstract
Fish serve as intermediate hosts for a number of larval parasites that have the potential of maturing in marine mammals such as Steller sea lions (Eumetopias jubatus). We examined the prevalence of parasites from 229 fish collected between March and July 2002 near two islands used by Steller sea lions in Southeast Alaska and island habitats in the Aleutian Islands. Sea lion populations have remained steady in Southeast Alaska but have been declining over the last 30 yr in the Aleutian Islands. Even though the fish samples near the Southeast Alaska haul-outs were composed of numerous small species of fish and the Aleutian Islands catch was dominated by juveniles of commercially harvested species, the parasite fauna was similar at all locations. Eleven of the 20 parasite taxa identified were in their larval stage in the fish hosts, several of which have been described from mammalian final hosts. Four species of parasite were more prevalent in Southeast Alaska fish samples, and seven parasite species, including several larval forms capable of infecting marine mammals, were more prevalent in fish from the Aleutian Islands. Nevertheless, parasites available to Steller sea lions from common fish prey are not likely to be a major factor in the decline of this marine mammal species.
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Affiliation(s)
- A Moles
- Alaska Fisheries Science Center, National Marine Fisheries Service, 11305 Glacier Highway, Juneau, Alaska 99801, USA.
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Heintz RA. Chronic exposure to polynuclear aromatic hydrocarbons in natal habitats leads to decreased equilibrium size, growth, and stability of pink salmon populations. Integr Environ Assess Manag 2007. [PMID: 17695108 DOI: 10.1002/ieam.5630030306] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/13/2023]
Abstract
The immediate and delayed effects of embryonic exposure to low levels of polynuclear aromatic hydrocarbons (PAHs) have been shown to reduce survival to maturity by 50% in exposed pink salmon populations. This suggests that chronically exposed populations could be extirpated over relatively few generations, but the effect of density dependence on extirpation rate is unknown. This study examines the interaction of PAH effects and randomly varying density dependence on a simulated population. The simulation derives from 70 years of observations made on a single pink salmon population and toxicity studies involving a hatchery population in the same watershed. Results from simulations involving exposure of 100% of the population to effects consistent with an aqueous PAH concentration of 18 nL/L indicate an 80% decrease in population productivity and an 11% probability of extinction after 35 generations. In contrast, population growth rate declined by only 5%. Further decreases in survival relative to that of observed PAH effects rapidly increase the probability of extinction. Data from these simulations demonstrate that, at low levels of exposure, density dependence can compensate for reduced population size and buffer the population against extinction. However, if equilibrium size is depressed sufficiently, random environmental variation overcomes the buffering effect of density dependence and extinction probability increases. These data demonstrate that extinction probability and population size are more sensitive measures of population effects than growth rate for wild populations regulated by density dependence.
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Affiliation(s)
- Ron A Heintz
- Alaska Fisheries Science Center, National Marine Fisheries Service, National Oceanic and Atmospheric Administration, Auke Bay Laboratory, 11305 Glacier Hwy, Juneau, Alaska 99801, USA.
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Barron MG, Carls MG, Short JW, Rice SD, Heintz RA, Rau M, Di Giulio R. Assessment of the phototoxicity of weathered Alaska North Slope crude oil to juvenile pink salmon. Chemosphere 2005; 60:105-10. [PMID: 15910909 DOI: 10.1016/j.chemosphere.2004.12.006] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/13/2004] [Revised: 11/05/2004] [Accepted: 12/02/2004] [Indexed: 05/02/2023]
Abstract
Petroleum products are known to have greater toxicity to the translucent embryos and larvae of aquatic organisms in the presence of ultraviolet radiation (UV) compared to toxicity determined in tests performed under standard laboratory lighting with minimal UV. This study assessed the acute phototoxicity of the water accommodated fractions of weathered Alaska North Slope crude oil (ANS) to juvenile pink salmon, which are a heavily pigmented life stage. Fish in the highest ANS treatments exhibited melanosis, less mobility, reduced startle response, erratic swimming, and loss of equilibrium. Gills from fish exposed to ANS had elevated levels of hydroperoxides in oil-only, UV-only, and oil+UV treatments compared to control fish, which was indicative of increased lipid peroxidation in gill tissue. Under the test conditions of moderate salinity, low UV and high short-term oil exposure there were no indications of photoenhanced toxicity as assessed by elevation of mortality, behavioral impairment, or gill lipid peroxidation in oil+UV treatments. The results of this study suggest that pink salmon may be at less risk from photoenhanced toxicity compared to the translucent early-life stages of several other Alaska species.
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Affiliation(s)
- Mace G Barron
- P.E.A.K. Research, 1130 Avon Lane, Longmont, CO 80501, United States.
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Carls MG, Holland LG, Short JW, Heintz RA, Rice SD. Monitoring polynuclear aromatic hydrocarbons in aqueous environments with passive low-density polyethylene membrane devices. Environ Toxicol Chem 2004; 23:1416-1424. [PMID: 15376527 DOI: 10.1897/03-395] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
Low-density polyethylene membranes, typically filled with triolein, have been previously deployed as passive environmental samplers designed to accumulate nonpolar hydrophobic chemicals from water, sediments, and air. Hydrocarbons in such samplers, known as semipermeable membrane devices (SPMDs), diffuse through pores in the membranes and are trapped in the central hydrocarbon matrix, mimicking uptake by living organisms. Here, we describe laboratory and field verification that low-density polyethylene membrane devices (PEMDs) without triolein provide reliable, relatively inexpensive, time-integrated hydrocarbon sampling from water. For comparison, polynuclear aromatic hydrocarbon (PAH) uptake in SPMDs and pink salmon eggs also was studied. Total concentrations of PAH accumulated by PEMDs were highly correlated with concentrations in water (r2 > or = 0.99) and linear over the range tested (0-17 microg/L). Higher-molecular-mass PAH preferentially accumulated in PEMDs and in pink salmon eggs, but the source of oil in PEMDs remained identifiable. Accumulations of PAH were highly similar to those in SPMDs. The PEMDs retained approximately 78% of accumulated total PAH for 40 d in clean water. Thus, a simple plastic membrane can be conveniently used for environmental monitoring, particularly during situations in which contaminant concentrations are low (in the parts-per-billion range), variable, and intermittent.
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Affiliation(s)
- Mark G Carls
- National Oceanic and Atmospheric Administration, National Marine Fisheries Service, Alaska Fisheries Science Center, Auke Bay Laboratory, 11305 Glacier Highway, Juneau, Alaska 99801, USA.
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Rice SD, Carls MG, Heintz RA, Short JW. Comment on "Hydrocarbon composition and toxicity of sediments following the Exxon Valdez oil spill in Prince William Sound, Alaska, USA". Environ Toxicol Chem 2003; 22:2539-2542. [PMID: 14587889 DOI: 10.1897/02-631] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
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Cowan JJ, Bailey AJ, Heintz RA, Do BT, Hardcastle KI, Hill CL, Weinstock IA. Formation, isomerization, and derivatization of Keggin tungstoaluminates. Inorg Chem 2001; 40:6666-75. [PMID: 11735477 DOI: 10.1021/ic0106120] [Citation(s) in RCA: 67] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Trends in the stability of alpha- and beta-Keggin heteropolytungstates of the second-row main-group heteroatoms Al(III), Si(IV), and P(V) are elaborated by data that establish the roles of kinetic and thermodynamic control in the formation and isomerization of Keggin tungstoaluminates. Slow, room-temperature co-condensation of Al(III) and W(VI) (2:11 molar ratio) in water gives a pH 7 solution containing beta(1) and beta(2) isomers of [Al(AlOH(2))W(11)O(39)](6)(-) (beta(1)- and beta(2)-1). Partial equilibration of this kinetic product mixture by gentle heating (2 h at 100 degrees C) or, alternatively, co-condensation of Al(III) and W(VI) for 2.5 h at 100 degrees C both give mixtures of beta(2)-, beta(3)-, and alpha-1. Full equilibration, by prolonged heating (25 days at 100 degrees C), gives an isomerically pure solution of alpha-1, thus demonstrating that isomerization occurs in the direction beta(1) --> beta(2) --> beta(3) --> alpha. Furthermore, kinetically controlled conversions of 1 to H(5)[AlW(12)O(40)] (2)-achieved by heating pH 0-0.2 solutions of 1 for 5 days at 100 degrees C-occur with retention of isomeric integrity, such that alpha-1 is converted to alpha-2 (92%; 8% beta), while mixtures of beta(2)- and beta(3)-1 are converted to beta-2 (87%; 13% alpha). These data, when combined with previously reported observations (equilibria between alpha- and beta-2, kinetically controlled hydrolyses of alpha-2 to alpha-[AlW(11)O(39)](9)(-) (alpha-3) and of beta-2 to beta(2)-3, and equilibria between beta(3)- and alpha-3), provide a comprehensive picture regarding the roles of kinetic and thermodynamic control. Finally, a general method for preparation of the isomerically pure derivatives alpha-K(9)(-)(n)()[AlM(n)()(+)W(11)O(39)] (4), M(n)()(+) = Al(III), [V(IV)O](2+), [V(V)O](3+), Mn(II), Mn(III), Mn(IV), Co(II), and Co(III), is provided. The presence of Mn(IV) is confirmed by cyclic voltammetry, pK(a) values of the aquo ligands on 4 are determined by pH titration, and the isomeric structure of these derivatives is established by (27)Al, (51)V, and (183)W NMR and IR spectroscopies and X-ray crystallography.
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Affiliation(s)
- J J Cowan
- Department of Chemistry, 1515 Pierce Drive, Emory University, Atlanta, Georgia 30322, USA
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Weinstock IA, Barbuzzi EM, Wemple MW, Cowan JJ, Reiner RS, Sonnen DM, Heintz RA, Bond JS, Hill CL. Equilibrating metal-oxide cluster ensembles for oxidation reactions using oxygen in water. Nature 2001; 414:191-5. [PMID: 11700554 DOI: 10.1038/35102545] [Citation(s) in RCA: 166] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Although many enzymes can readily and selectively use oxygen in water-the most familiar and attractive of all oxidants and solvents, respectively-the design of synthetic catalysts for selective water-based oxidation processes utilizing molecular oxygen remains a daunting task. Particularly problematic is the fact that oxidation of substrates by O2 involves radical chemistry, which is intrinsically non-selective and difficult to control. In addition, metallo-organic catalysts are inherently susceptible to degradation by oxygen-based radicals, while their transition-metal-ion active sites often react with water to give insoluble, and thus inactive, oxides or hydroxides. Furthermore, pH control is often required to avoid acid or base degradation of organic substrates or products. Unlike metallo-organic catalysts, polyoxometalate anions are oxidatively stable and are reversible oxidants for use with O2 (refs 8,9,10). Here we show how thermodynamically controlled self-assembly of an equilibrated ensemble of polyoxometalates, with the heteropolytungstate anion [AIVVW11O40]6- as its main component, imparts both stability in water and internal pH-management. Designed to operate at near-neutral pH, this system facilitates a two-step O2-based process for the selective delignification of wood (lignocellulose) fibres. By directly monitoring the central Al atom, we show that equilibration reactions typical of polyoxometalate anions keep the pH of the system near 7 during both process steps.
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Affiliation(s)
- I A Weinstock
- Chemistry and Pulping Research Work Unit, USDA Forest Service, Forest Products Laboratory, Madison, Wisconsin 53705, USA.
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