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Wittkop, C, Teranes J, Lubenow B, Dean WE.  2014.  Carbon- and oxygen-stable isotopic signatures of methanogenesis, temperature, and water column stratification in Holocene siderite varves. Chemical Geology. 389:153-166.   10.1016/j.chemgeo.2014.09.016   AbstractWebsite

Manganoan siderite ([Fe,Mn]CO3) occurs in abundance of up to 19% (dry weight) as the sole endogenic carbonate within a succession of Holocene, organic-rich, varved sediments from freshwater Otter Lake (OL), Michigan. Radiocarbon dating and varve counts from a 7-m piston core constrain periods of major siderite accumulation to sediments older than 1200 cal yr BP. Sediment petrography suggests that siderite was a seasonal precipitate confined to the summer layer of the varve couplet. Bulk-sediment chemistry reveals cycles in abundance of manganese and aluminum coincident with centennial-scale cycles of siderite accumulation. Siderite delta C-13 and delta O-18 are enriched when the mineral is abundant and depleted when it is least abundant. Samples with high abundance of siderite precipitated in oxygen isotopic equilibrium with modern lake water, but are delta C-13 enriched relative to modern waters. Samples from intervals of low siderite abundance are delta C-13 and delta O-18 depleted relative to equilibrium with modern lake water. These data suggest that abundant siderite precipitation occurred when the OL water column was ferruginous (iron meromictic), allowing for enhanced ferrous iron concentrations and dissolved inorganic carbon (DIC) enriched in delta C-13 below the chemocline, where methanogenesis in waters and sediments influenced DIC composition. Seasonal siderite precipitation was triggered by water column alkalinity fluctuations driven by summer calcite dissolution. Manganese substitution in siderite lowered kinetic barriers to low-temperature mineral precipitation. Climate changes and basin filling influenced lake stratification and the rate of siderite precipitation. The siderite occurrence reported here displays remarkable similarity to its occurrence in Paleogene maar lake deposits, suggesting that further studies of Holocene lacustrine siderites may provide insight into ancient sedimentary systems and environments. (C) 2014 Elsevier B.V. All rights reserved.

Wittkop, CA, Teranes JL, Dean WE, Guilderson TP.  2009.  A lacustrine carbonate record of Holocene seasonality and climate. Geology. 37:695-698.   10.1130/g30056a.1   AbstractWebsite

Annually laminated (varved) Holocene sediments from Derby Lake, Michigan, display variations in endogenic calcite abundance reflecting a long-term (millennial-scale) decrease in burial punctuated with frequent short-term (decadal-scale) oscillations due to carbonate dissolution. Since 6000 cal yr B. P., sediment carbonate abundance has followed a decreasing trend while organic-carbon abundance has increased. The correlation between organic-carbon abundance and the sum of March-April-October-November insolation has an r(2) value of 0.58. We interpret these trends to represent a precession-driven lengthening of the Holocene growing season that has reduced calcite burial by enhancing net annual organic-matter production and associated calcite dissolution. Correlations with regional paleoclimate records suggest that changes in temperature and moisture balance have impacted the distribution of short-term oscillations in carbonate and organic-matter abundance superimposed on the precession-driven trends.

Ekdahl, EJ, Teranes JL, Wittkop CA, Stoermer EF, Reavie ED, Smol JP.  2007.  Diatom assemblage response to Iroquoian and Euro-Canadian eutrophication of Crawford Lake, Ontario, Canada. Journal of Paleolimnology. 37:233-246.   10.1007/s10933-006-9016-7   AbstractWebsite

Diatom and geochemical data from Crawford Lake, Ontario, have been used to document limnological responses to periods of cultural disturbance resulting from native Iroquoian occupation of the watershed (1268-1486 AD) and Euro-Canadian agriculture and deforestation (1867 AD-present). Here, we further develop the high-resolution nature of the Crawford Lake sediment record to examine the physical, chemical and biological aspects of limnological response to human disturbances in the lake catchment area with exceptional detail. We report detailed diatom abundance and flux data for individual taxa from Crawford Lake, and further describe the relationship between assemblage composition and environmental conditions using canonical correspondence analysis (CCA). Diatom assemblage data are used to calculate diatom inferred-total phosphorus (DI-TP) concentrations for the past similar to 1,000 years. We also examine the diatom community response during and after periods of disturbance by Iroquoian and Euro-Canadian populations, and compare this response to existing geochemical proxies of lake production and new elemental geochemical indicators of catchment area erosion. In particular, we explore the differing limnological response to the two distinct periods of cultural eutrophication and examine the limnological processes that occurred during the period of low (or no) human activity (1487-1866 AD), when geochemical indicators of lake production recovered to pre-disturbance conditions, but diatom assemblages notably did not. Our results illustrate the highly susceptible nature of diatom communities to periods of anthropogenic disturbance, and emphasize that ecological indicators (such as diatom assemblages) should be included with other proxies (such as nutrient concentrations and physical characteristics) when assessing disturbance and recovery in lake systems.

Teranes, JL, Bernasconi SM.  2005.  Factors controlling δ13C values of sedimentary carbon in hypertrophic Baldeggersee, Switzerland, and implications for interpreting isotope excursions in lake sedimentary records. Limnology and Oceanography. 50:914-922. AbstractWebsite

We use stable carbon isotope values (delta(13)C) in sedimented organic matter and carbonate as proxy indicators of productivity changes in a highly eutrophic to hypertrophic lake. Stable isotope data from a seasonally sampled sediment core recovered from Baldeggersee, Switzerland were compared with direct and inferred total phosphorus (P) concentrations. Carbon isotope values of sedimentary organic matter (delta(13)C(org)) in both seasonal varves and over the past 100 yr are not linearly related to total P concentrations, nor do they mirror observed trends in carbonate isotope values (delta(13)C(CaCO3)). Baldeggersee delta(13)C(org) values are influenced by both variations in the relative inputs of eukaryotic biomass, which becomes enriched in C-13 with increasing primary productivity, and the contribution of microbial biomass produced in the expanding anoxic bottom waters, which is typically very depleted in C-13. We also examined the fractionation within the organic matter-CO2-CaCO3 system, calculated as epsilon(total organic carbor(TOC)) = 10(3){[(delta(13)C(CaCO3) + 1,000)/(delta(13)C(org) + 1,000)] - 1}. Thresholds within the measured epsilon(TOC) values represent Baldeggersee trophic status more accurately than delta(13)C(org) or delta(13)C(CaCO3) values alone. In alkaline lakes with endogenic carbonate precipitates, STOC values can facilitate accurate interpretation of values and trends in organic carbon isotope data, and can help to better assess trophic history and lake remediation efforts in lake systems that have been heavily affected by cultural eutrophication.

Ekdahl, EJ, Teranes JL, Guilderson TP, Turton CL, McAndrews JH, Wittkop CA, Stoermer EF.  2004.  Prehistorical record of cultural eutrophication from Crawford Lake, Canada. Geology. 32:745-748.   10.1130/g20496.1   AbstractWebsite

Cultural eutrophication-the process by which human activities increase nutrient input rates to aquatic ecosystems and thereby cause undesirable changes in surface-water quality-is generally thought to have begun with the start of the industrial era. The prehistoric dimension of human impacts on aquatic ecosystems remains relatively undescribed, particularly in North America. Here we present fossil plankton data (diatoms and rotifers), organic and inorganic carbon accumulations, and carbon isotope ratios from a 1000 yr sediment core record from Crawford Lake, Ontario, Canada. The data document increased nutrient input to Crawford Lake caused by Iroquoian horticultural activity from A.D. 1268 to 1486 and show how this increased nutrient input elevated lake productivity, caused bottom-water anoxia, and irreversibly altered diatom community structure within just a few years. Iroquoian settlement in the region declined in the fifteenth century, yet diatom communities and lake circulation never recovered to the predisturbance state. A second phase of cultural eutrophication starting in A.D. 1867, initiated by Canadian agricultural disturbance, increased lake productivity but had comparatively less impact on diatom assemblages and carbon-storage pathways than the initial Iroquoian disturbance. This study deepens our understanding of the impact of cultural eutrophication on lake systems, highlights the lasting influence of initial environmental perturbation, and contributes to the debate on the ecological impacts of density and agricultural practices of native North American inhabitants.

van Zuilen, MA, Lepland A, Teranes J, Finarelli J, Wahlen M, Arrhenius G.  2003.  Graphite and carbonates in the 3.8 Ga old Isua Supracrustal Belt, southern West Greenland. Precambrian Research. 126:331-348.   10.1016/s0301-9268(03)00103-7   AbstractWebsite

We present a systematic study of abundance, isotopic composition and petrographic associations of graphite in rocks from the ca. 3.8 Ga Isua Supracrustal Belt (ISB) in southern West Greenland. Most of the graphite in the ISB occurs in carbonate-rich metasomatic rocks (metacarbonates) while sedimentary units, including banded iron formations (BIFs) and metacherts, have exceedingly low graphite concentrations. Regardless of isotopic composition of graphite in metacarbonate rocks, their secondary origin disqualifies them from providing evidence for traces of life stemming from 3.8 Ga. Recognition of the secondary origin of Isua metacarbonates thus calls for reevaluation of earlier interpretations that suggested the occurrence of 3.8 Ga biogenic graphite in these rocks. Thermal decomposition of siderite; 6FeCO(3) = 2Fe(3)O(4) + 5CO(2) + C, is the process seemingly responsible for the graphite formation. The cation composition (Fe, Mg, Mn, and Ca) of the carbonate minerals, carbon isotope ratios of carbonates and associated graphite and petrographic assemblages of a suite of metacarbonates support the conclusion that multiple pulses of metasomatism affected the ISB, causing the deposition of Fe-bearing carbonates and subsequent partial disproportionation to graphite and magnetite. Equilibrium isotope fractionation between carbonate and graphite in the rocks indicates peak metamorphic temperatures between 500 and 600degreesC, in agreement with other estimates of metamorphic temperature for the ISB. Published by Elsevier B.V.

Teranes, JL, McKenzie JA.  2001.  Lacustrine oxygen isotope record of 20(th)-century climate change in central Europe: evaluation of climatic controls on oxygen isotopes in precipitation. Journal of Paleolimnology. 26:131-146.   10.1023/a:1011175701502   AbstractWebsite

We report oxygen isotope data from a 108-yr (1885-1993) sequence with annual laminae of bio-induced authigenic calcite in a frozen core from Baldeggersee, a small lake in Central Switzerland. These isotope results provide proxy data on the isotopic composition of past precipitation in the Baldeggersee catchment region and are quantitatively compared with instrumental climate data (i.e. mean annual air temperature and atmospheric circulation pattern indices) to evaluate climatic controls on oxygen isotopes in precipitation. Monitoring the isotope hydrology of Baldeggersee demonstrates that the oxygen isotopic composition of the lake water is controlled by the isotopic composition of local atmospheric precipitation (delta O-18(p)) and that the isotopic signal of precipitation is preserved, albeit damped, in the lake calcite oxygen isotope record (delta O-18(c)). Comparison of the calcite oxygen isotope proxy for delta O-18(p) in the catchment with historical mean annual air temperature measurements from Bern, Switzerland confirms that authigenic calcite reliably records past annual air temperature in the region. This delta O-18(c)/temperature relationship is calculated to be 0.39 parts per thousand/degreesC for the period 1900-1960, based on an isotope mass-balance model for Baldeggersee. An exception is a 0.8 parts per thousand anomalous negative shift in calcite delta O-18 values since the 1960s. Possible explanations for this recent delta O-18(c) shift, as it is not related to mean annual air temperature, include changes in delta O-18(p) due to synoptic circulation patterns. In particular, the 0.8 parts per thousand negative shift coincides with a trend towards a more dominant North Atlantic Oscillation (NAO) index. This circulation pattern would tend to bring more isotopically more negative winter precipitation to the region and could account for the 0.8 parts per thousand offset in delta O-18(c) data.

Meyers, PA, Teranes JL.  2001.  Sediment Organic Matter. Tracking environmental change using lake sediments. Volume 2, Physical and geochemical methods. 2( Last WM, Smol JP, Eds.).:239-270., Dordrecht; Boston: Kluwer Academic Publishers Abstract
Teranes, JL, Bernasconi SM.  2000.  The record of nitrate utilization and productivity limitation provided by δ15N values in lake organic matter - A study of sediment trap and core sediments from Baldeggersee, Switzerland. Limnology and Oceanography. 45:801-813. AbstractWebsite

The response of nitrogen isotopic composition of organic matter to changes in nitrate utilization, N-limitation and lake productivity was studied in Baldeggersee, a small eutrophic lake in central Switzerland. Nitrogen isotope ratios were measured on organic matter accumulation in sediment traps, collected daily from March 1995 through October 1996, and on individually sampled light and dark annual laminae from a 108-yr sediment core sequence (1885-1993). Nitrogen accumulation in the sediment traps averaged 0.04 g N m(-2) d(-1). delta(15)N values of the sediment trap material increased from 11 parts per thousand to 13 parts per thousand (atmospheric N-2) as primary productivity decreased surface water [NO3-] from 1.4 to 0.7 mg N L-1 during the seasonal stratified periods. Very small amounts of isotopically enriched organic matter (delta(15)N similar to 15-20 parts per thousand) of heterotrophic and/or detrital origin accumulated in the winter months. Nitrogen accumulation in the core sediments average 4 g N m(-2) per year. delta(15)N values of the sediment core material increased up-core (from delta(15)N similar to 6 parts per thousand to delta(15)N similar to 11 parts per thousand); several abrupt positive isotope shifts (>2 parts per thousand) occur in the upper Dart of the record. Comparison between sediment delta(15)N values and surface water [NO3-] measurements for the period of 1976-1993 reveals that the abrupt positive delta(15)N shifts occurred in years where unusually large phytoplankton blooms depleted surface waters nitrate to concentrations of <0.7 mg N L-1. A 3 parts per thousand negative delta(15)N shift, observed between 1973-1975 at the time of maximum anoxic conditions and meromixis, can be attributed to phytoplankton incorporation of ammonia, which was present in concentrations of up to 0.7 mg L-1 in the epilimnion. Preservation of isotopic shifts in the sediment core which are clearly related to water column processes, and the similarity of core top delta(15)N values to the weighted average N-isotopic composition of sediment trap material indicate that the sediment record reliably reflects the surface-generated delta(15)N signal. Our results from sediment trap and uppermost core samples provide the first conclusive evidence that N-isotopes in lacustrine organic matter record the increasing isotopic enrichment of surface water NO3- due to its utilization by phytoplankton. Artificial aeration of the Baldeggersee bottom water since 1982 has effectively reduced water column anoxia. Thus, water column denitrification, which could considerably increase the isotopic composition of residual nitrate, does not occur in the present lake. Even so, present day nitrogen isotopic values in the sediment core data are higher than most all previous periods suggesting that water column denitrification has never been a dominant influence on sediment delta(15)N values. Instead, the up-core 6 parts per thousand increase in delta(15)N values better corresponds to the documented history of external N-loading from agricultural runoff in the watershed over the last 100 years. These nitrogen sources have characteristically high delta(15)N values (10-20 parts per thousand) and could lead to progressive N-15-enrichment of the Baldeggersee dissolved inorganic nitrogen pool.

Teranes, JL, McKenzie JA, Lotter AF.  1999.  Stable isotope response to lake eutrophication: Calibration of a high-resolution lacustrine sequence from Baldeggersee, Switzerland. Limnology and Oceanography. 44:320-333. AbstractWebsite

Stable isotope analyses of discrete seasonal layers from a 108-yr annually laminated freeze-core from Baldeggersee, a small, eutrophic lake in central Switzerland, provide information on the climatological and environmental factors, including lake eutrophication, that control oxygen and carbon isotopic composition of epilimnic biologically induced calcite precipitate. During the last 100 yr, Baldeggersee has undergone major increases in productivity and eutrophication in response to nutrient loading from agriculture and industrialization in the lake's watershed. Calibration of the isotopic signal in Baldeggersec to historical limnological data quantitatively links evidence of isotopic depletion in the sedimented calcite to trophic state of the lake. delta(18)O values from the spring/summer "light" sediment layers steadily diverged to more depleted values in response to historical eutrophication: measured delta(18)O values were up to -1.5 parts per thousand more negative than calculated equilibrium delta(18)O values. Evidence for C-13 depletion in the calcite, relative to equilibrium values, is more difficult to ascertain because of an overall dominance of isotopic enrichment in the dissolved inorganic pool as productivity in Baldeggersee increases. A positive association exists between the degree of oxygen 18 depletion and the calcite crystal size. Thus, large amorphous calcite grains can be used as a proxy for recognizing apparent isotopic nonequilibrium in sediment sequences from highly productive lacustrine environments from all geologic time scales. In contrast to the light layers, the oxygen isotopic composition of the calcite in the late summer/fall "dark" sediment layers is unaffected by the apparent isotope nonequilibrium. Oxygen and carbon isotope values from the dark laminae in the Baldeggersee sediment therefore provide environmental and climatological proxies that can be calibrated with known environmental and regional climate data for the last century.

Teranes, JL, McKenzie JA, Bernasconi SM, Lotter AF, Sturm M.  1999.  A study of oxygen isotopic fractionation during bio-induced calcite precipitation in eutrophic Baldeggersee, Switzerland. Geochimica Et Cosmochimica Acta. 63:1981-1989.   10.1016/s0016-7037(99)00049-6   AbstractWebsite

In order to better understand environmental factors controlling oxygen isotope shifts in autochthonous lacustrine carbonate sequences, we undertook an extensive one year study (March, 1995 to February, 1996) of water-column chemistry and daily sediment trap material from a small lake in Central Switzerland. Comparisons between calculated equilibrium isotope values, using the fractionation equation of Friedman and O'Neil (1977) and measured oxygen isotope ratios of calcite in the sediment-traps reveal that oxygen isotopic values of autochthonous calcite (delta(18)O) are in isotopic equilibrium with ambient water during most of the spring and summer, when the majority of the calcite precipitates. In contrast, small amounts of calcite precipitated in early-spring and again in late-autumn are isotopically depleted in O-18 relative to the calculated equilibrium values, by as much as 0.8 parts per thousand. This seasonally occurring apparent isotopic nonequilibrium is associated with times of high phosphorous concentrations, elevated pH (similar to 8.6) and increased [CO32-] (similar to 50 mu mol/l) in the surface waters. The resulting weighted average delta(18)O Value for the studied period is -9.6 parts per thousand, compared with a calculated equilibrium delta(18)O value of -9.4 parts per thousand. These data convincingly demonstrate that delta(18)O of calcite are, for the most part, a very reliable proxy for temperature and delta(18)O Of the water. Copyright (C) 1999 Elsevier Science Ltd.

Lotter, AF, Sturm M, Teranes JL, Wehrli B.  1997.  Varve formation since 1885 and high-resolution varve analyses in hypertrophic Baldeggersee (Switzerland). Aquatic Sciences. 59:304-325.   10.1007/bf02522361   AbstractWebsite

According to their microstratigraphical composition the laminated sediments of Baldeggersee are true varves. Two varve time-series from freeze cores taken in the deepest part (66 m) of Baldeggersee have been analysed for annual and seasonal layers. The varve time-series covers the period of 1885 to 1993. The two freeze-cores from Baldeggersee can be accurately correlated by means of distinct lay ers (e.g. marker varves, turbidites), lithological units, and varve measurements. The Baldeggersee varve chronology has been checked by independent high-resolution Cs-137 dating. Mobility of cesium has not been detected in Baldeggersee. A highly positive correlation between phosphorus concentration in the lake water and median grain size of calcite crystals has been observed and allows, together with the results of geochemical analyses, to hindcast the trophic state in Baldeggersee for periods where no limnological data are available. The main features of the Baldeggersee varve time-series can be summarized as follows: before 1885 there are packets of 5-10 varves interrupted by massive, homogeneous marl beds, indicating oscillating hypolimnetic oxygen levels until the lake ultimately became anoxic in 1885. Between 1885 and 1905 varves are thin, with a high carbonate content. Between 1905 and 1910 the thickness of varves increased steadily, and an increase in calcite grain size suggests a major step in eutrophication. Median grain size values increase again at the end of the 1940s, whereas the thickness of the seasonal lavers decreased between the early 1940s and the early 1960s. At the onset of the 1960s, during the time of highest epilimnetic phosphorus concentrations in Baldeggersee, the total phosphorus concentrations in the sediments as well as the varve thickness and the total accumulation rates all increased. At the beginning of the 1980s the median grain size decreased substantially as a result of lower phosphorus concentrations in Baldeggersee.

Teranes, JL, Geary DH, Bemis BE.  1996.  The oxygen isotopic record of seasonality in Neogene bivalves from the Central American Isthmus. Evolution and Environment in Tropical America. ( Jackson JBC, Budd AF, Coates AG, Eds.).:105-129., Chicago: University of Chicago Press Abstract

How were the tropical Americas formed? This ambitious volume draws on extensive, multidisciplinary research to develop new views of the geological formation of the isthmus linking North and South America and of the major environmental changes that reshaped the Neotropics to create its present-day-marine and terrestrial ecosystems.

Ariztegui, D, Chondrogianni C, Wolff GA, Asioli A, Teranes JL, Bernasconi SM, McKenzie JA.  1996.  Paleotemperature and paleosaliniity history of the Meso Adriatic Depression (MAD) during the Late Quaternary: a stable isotopes and alkenones study. Palaeoenvironmental analysis of Italian crater lake and Adriatic sediments (PALICLAS). 55( Guilizzoni P, Oldfield F, Eds.).:219-230., Verbania Pallanza [Italy]: Consiglio nazionale delle ricerche, Istituto italiano di idrobiologia Abstract