Broxton Bird
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Fluvial Erosion Hazard Research and Education in Indiana
Professor Broxton Bird's research addresses a range of environmental questions. He is particularly interested in the intersection between climate change and water resources and the impacts on natural and anthropogenic systems. His current projects are focused on developing new hydroclimate records from Tibet, tropical South America, and the midwestern US in order to reconstruct the spatiotemporal patterns and mechanisms of hydrologic variability.
Professor Bird is also the Director of the Center for Earth and Environmental Science (CEES). For over 11 years, CEES has studied how Indiana rivers move, not only now but in the past, to better understand how erosion hazard may change as the climate continues to change. CEES faculty and staff have participated in over a dozen regional workshops and seminars and gave more than two hundred presentations around Indiana, neighboring states, and at national conferences. CEES has also expanded to include Burke Engineering to deliver a more balanced agency, academic, and private consultant perspective on fluvial erosion hazards CEES has published several documents on how Indiana’s river’s function and how the rivers and streams can be managed to maximize stream health and public safety.
Professor Bird's translation of research into improved water quality for communities all around the world is another excellent example of how IUPUI's faculty members are TRANSLATING their RESEARCH INTO PRACTICE.
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Recent Submissions
Item Multi-biomarker analysis of sediments for paleoclimate research(2017) Callegaro, Alice; Kirchgeorg, Torben; Argiriadis, Elena; Battistel, Dario; Kehrwald, Natalie M.; Bird, Broxton W.; Barbante, CarloLacustrine sedimentary cores provide continuous records of large-scale and local environmental modifications, intelligible thanks to specific organic markers that accumulated in these archives during past millennia. In order to improve our knowledge on ecosystem changes due to biomass burning events and human presence during the Holocene, an effective analytical method to detect organic compounds contained in sediment samples is needed. We used Accelerated Solvent Extraction (ASE) technique followed by analysis with gas and liquid chromatographers coupled with mass spectrometers (GC-MS, IC-MS). The extraction of the molecules of interest from the sediments is made with a mixture of DCM:MeOH 9:1 v/v and it is followed by a 3 steps purification with silica gel columns. The first fraction is eluted with HEX:DCM 9:1 v/v and contains n-alkanes, indicators of vegetation, and polycyclic aromatic hydrocarbons (PAHs) as combustion proxies. Then, a second fraction is eluted with DCM and derivatized with the silylation process, in order to get the faecal sterols and stanols (FeSts), indicators of past human and grazing animals presence. These two fractions are analysed with the GC-MS technique. The third and last fraction is eluted with MeOH and contains the monosaccharide anhydrides (MAs), specific indicators of vegetation burning processes, which are analysed with IC-MS. Internal standards labelled C13 are used for the quantification and procedural blanks are extracted every batch of 12 samples. The method may undergo variations, on the basis of the complex sediment matrices which not always lend itself to the same kind of treatment. However, the technique was applied in different lakes from different continents and the obtained results, compared with historical and climate literature data, seem to demonstrate the potentiality of the method as a resourceful instrument to reconstruct past burning events and human-ecosystem interactions.Item Forest–savanna–morichal dynamics in relation to fire and human occupation in the southern Gran Sabana (SE Venezuela) during the last millennia(Elsevier, 2011-11) Montoya, Encarni; Rull, Valentí; Stansell, Nathan D.; Abbott, Mark B.; Nogué, Sandra; Bird, Broxton W.; Díaz, Wilmer A.The southern Gran Sabana (SE Venezuela) holds a particular type of neotropical savanna characterized by the local occurrence of morichales (Mauritia palm swamps), in a climate apparently more suitable for rain forests. We present a paleoecological analysis of the last millennia of Lake Chonita (4°39′N–61°0′W, 884 m elevation), based on biological and physico-chemical proxies. Savannas dominated the region during the last millennia, but a significant vegetation replacement occurred in recent times. The site was covered by a treeless savanna with nearby rainforests from 3640 to 2180 cal yr BP. Water levels were higher than today until about 2800 cal yr BP. Forests retreated since about 2180 cal yr BP onwards, likely influenced by a higher fire incidence that facilitated a dramatic expansion of morichales. The simultaneous appearance of charcoal particles and Mauritia pollen around 2000 cal yr BP supports the potential pyrophilous nature of this palm and the importance of fire for its recent expansion. The whole picture suggests human settlements similar to today – in which fire is an essential element – since around 2000 yr ago. Therefore, present-day southern Gran Sabana landscapes seem to have been the result of the synergy between biogeographical, climatic and anthropogenic factors, mostly fire.Item A review of the South American monsoon history as recorded in stable isotopic proxies over the past two millennia(European Geosciences Union, 2012-08-23) Vuille, M.; Burns, S. J.; Taylor, B. L.; Cruz, F. W.; Bird, B. W.; Abbott, M. B.; Kanner, L. C.; Cheng, H.; Novello, V. F.We review the history of the South American summer monsoon (SASM) over the past ~2000 yr based on high-resolution stable isotope proxies from speleothems, ice cores and lake sediments. Our review is complemented by an analysis of an isotope-enabled atmospheric general circulation model (GCM) for the past 130 yr. Proxy records from the monsoon belt in the tropical Andes and SE Brazil show a very coherent behavior over the past 2 millennia with significant decadal to multidecadal variability superimposed on large excursions during three key periods: the Medieval Climate Anomaly (MCA), the Little Ice Age (LIA) and the current warm period (CWP). We interpret these three periods as times when the SASM's mean state was significantly weakened (MCA and CWP) and strengthened (LIA), respectively. During the LIA each of the proxy archives considered contains the most negative δ18O values recorded during the entire record length. On the other hand, the monsoon strength is currently rather weak in a 2000-yr historical perspective, rivaled only by the low intensity during the MCA. Our climatic interpretation of these archives is consistent with our isotope-based GCM analysis, which suggests that these sites are sensitive recorders of large-scale monsoon variations. We hypothesize that these centennial-scale climate anomalies were at least partially driven by temperature changes in the Northern Hemisphere and in particular over the North Atlantic, leading to a latitudinal displacement of the ITCZ and a change in monsoon intensity (amount of rainfall upstream over the Amazon Basin). This interpretation is supported by several independent records from different proxy archives and modeling studies. Although ENSO is the main forcing for δ18O variability over tropical South America on interannual time scales, our results suggest that its influence may be significantly modulated by North Atlantic climate variability on longer time scales. Finally, our analyses indicate that isotopic proxies, because of their ability to integrate climatic information on large spatial scales, could complement more traditional proxies such as tree rings or documentary evidence. Future climate reconstruction efforts could potentially benefit from including isotopic proxies as large-scale predictors in order to better constrain past changes in the atmospheric circulation.Item The impact of over 100 years of wildfires on mercury levels and accumulation rates in two lakes in southern California, USA(Springer, 2010-05-01) Rothenberg, Sarah E.; Kirby, Matthew E.; Bird, Broxton W.; DeRose, Margie B.; Lin, Chu-Ching; Feng, Xinbin; Ambrose, Richard F.; Jay, Jennifer A.In southern California, USA, wildfires may be an important source of mercury (Hg) to local watersheds. Hg levels and Hg accumulation rates were investigated in dated sediment cores from two southern California lakes, Big Bear Lake and Crystal Lake, located approximately 40-km apart. Between 1895 and 2006, fires were routinely minimized or suppressed around Big Bear Lake, while fires regularly subsumed the forest surrounding Crystal Lake. Mean Hg concentrations and mean Hg accumulation rates were significantly higher in Crystal Lake sediments compared to Big Bear Lake sediments (Hg levels: Crystal Lake 220 ± 93 ng g−1, Big Bear Lake 92 ± 26 ng g−1; Hg accumulation: Crystal Lake 790 ± 1,200 μg m−2 year−1, Big Bear 240 ± 54 μg m−2 year−1). In Crystal Lake, the ratio between post-1965 and pre-1865 Hg concentrations was 1.1, and several spikes in Hg levels occurred between 1910 and 1985. Given the remote location of the lake, the proximity of fires, and the lack of point sources within the region, these results suggested wildfires (rather than industrial sources) were a continuous source of Hg to Crystal Lake over the last 150 years.Item Self-efficacy for coping with cancer in a multiethnic sample of breast cancer patients: Associations with barriers to pain management and distress(Wolters Kluwer, 2010) Mosher, Catherine E.; DuHamel, Katherine N.; Egert, Jennifer; Smith, Meredith Y.Objectives This study examined the interrelations of self-efficacy for coping with cancer, perceived barriers to pain management, distress, and pain outcomes in a multiethnic sample of breast cancer patients. The extent to which ethnicity (Black, Latina, or White), language (English or Spanish), and level of education and income predicted these variables was also assessed. Methods Participants were breast cancer patients with persistent pain (N=87) who were recruited from oncology clinics in New York City. Patients completed an assessment battery that included measures of self-efficacy for coping with cancer, barriers to pain management, distress, and pain outcomes. Results Greater self-efficacy for coping with cancer was associated with older age, less time since diagnosis, and less distress. In addition, less self-efficacy for seeking and understanding medical information, Spanish language preference, and greater distress predicted greater barriers to pain management. Average pain severity was higher among Spanish-speaking individuals and those with lower incomes. Discussion Findings point to the potential importance of self-efficacy for seeking and understanding medical information and perceived barriers to pain management in understanding the psychologic well-being of breast cancer patients with pain, especially those who are Spanish-speaking.Item A Holocene record of Pacific Decadal Oscillation (PDO)-related hydrologic variability in Southern California (Lake Elsinore, CA)(Springer, 2010-10-01) Kirby, M. E.; Lund, S. P.; Patterson, W. P.; Anderson, M. A.; Bird, B. W.; Ivanovici, L.; Monarrez, P.; Nielsen, S.High-resolution terrestrial records of Holocene climate from Southern California are scarce. Moreover, there are no records of Pacific Decadal Oscillation (PDO) variability, a major driver of decadal to multi-decadal climate variability for the region, older than 1,000 years. Recent research on Lake Elsinore, however, has shown that the lake’s sediments hold excellent potential for paleoenvironmental analysis and reconstruction. New 1-cm contiguous grain size data reveal a more complex Holocene climate history for Southern California than previously recognized at the site. A modern comparison between the twentieth century PDO index, lake level change, San Jacinto River discharge, and percent sand suggests that sand content is a reasonable, qualitative proxy for PDO-related, hydrologic variability at both multi-decadal-to-centennial as well as event (i.e. storm) timescales. A depositional model is proposed to explain the sand-hydrologic proxy. The sand-hydrologic proxy data reveal nine centennial-scale intervals of wet and dry climate throughout the Holocene. Percent total sand values >1.5 standard deviation above the 150–9,700 cal year BP average are frequent between 9,700 and 3,200 cal year BP (n = 41), but they are rare from 3,200 to 150 cal year BP (n = 6). This disparity is interpreted as a change in the frequency of exceptionally wet (high discharge) years and/or changes in large storm activity. A comparison to other regional hydrologic proxies (10 sites) shows more then occasional similarities across the region (i.e. 6 of 9 Elsinore wet intervals are present at >50% of the comparison sites). Only the early Holocene and the Little Ice Age intervals, however, are interpreted consistently across the region as uniformly wet (≥80% of the comparison sites). A comparison to two ENSO reconstructions indicates little, if any, correlation to the Elsinore data, suggesting that ENSO variability is not the predominant forcing of Holocene climate in Southern California.Item Ocean-atmosphere forcing of centennial hydroclimate variability in the Pacific Northwest(AGU, 2014-03-11) Steinman, Byron A.; Abbott, Mark B.; Mann, Michael E.; Ortiz, Joseph D.; Feng, Song; Pompeani, David P.; Stansell, Nathan D.; Anderson, Lesleigh; Finney, Bruce P.; Bird, Broxton W.; Earth Sciences, School of ScienceReconstructing centennial timescale hydroclimate variability during the late Holocene is critically important for understanding large-scale patterns of drought and their relationship with climate dynamics. We present sediment oxygen isotope records spanning the last two millennia from 10 lakes, as well as climate model simulations, indicating that the Little Ice Age was dry relative to the Medieval Climate Anomaly in much of the Pacific Northwest of North America. This pattern is consistent with observed associations between the El Niño–Southern Oscillation (ENSO), the Northern Annular Mode, and drought as well as with proxy-based reconstructions of Pacific and Atlantic ocean-atmosphere variations over the past 1000 years. The large amplitude of centennial variability indicated by the lake data suggests that regional hydroclimate is characterized by longer-term shifts in ENSO-like dynamics and that an improved understanding of the centennial timescale relationship between external forcing and drought is necessary for projecting future hydroclimatic conditions in western North America.Item Hydrogen isotopic composition (δ2H) of diatom-derived C20 highly branched isoprenoids from lake sediments tracks lake water δ2H(Elsevier, 2020-12) Corcoran, Megan C.; Diefendorf, Aaron F.; Lowell, Thomas V.; Freimuth, Erika J.; Schartman, Anna K.; Bates, Benjamin R.; Stewart, Alexander K.; Bird, Broxton W.; Earth Sciences, School of ScienceThe hydrogen isotopic composition of lake water (δ2Hlw) reflects hydrological processes, which can yield information about evaporation and precipitation changes through time when preserved in lake sediment archives. Unfortunately, few proxies exist that record only δ2Hlw. Instead, most δ2Hlw records represent a mix of aquatic and terrestrial material. Highly branched isoprenoids (HBIs), known to be produced by diatoms in marine and lacustrine settings, may be used as a lake water proxy to directly reconstruct hydroclimate, if the hydrogen isotopic composition of HBIs (δ2HHBI) reflects the δ2Hlw. We test this hypothesis by analyzing 78 sediment samples from 12 lakes in the Adirondack Mountains in New York, for HBI concentrations and δ2H. δ2HHBI was compared to δ2Hlw, which showed an average fractionation (εHBI/lw) of −127.3 ± 15.0‰ (1σ) for all samples in all lakes. Consistency in εHBI/lw between samples implies that δ2HHBI may be used to reconstruct δ2Hlw through time, to help assess how lake systems have changed in the past. Sediment samples collected from deeper (>4 m) zones within the lake had smaller variability in εHBI/lw (±11.9‰, 1σ) than samples from shallower zones, suggesting that εHBI/lw may be sensitive to other factors, such as light availability, which may be related to differences in diatom growth habit (e.g., benthic, planktonic). Similarly, the carbon isotopes of HBIs (δ13CHBI) were higher for sediment samples collected in deeper zones in the lake, suggesting that δ13CHBI can be used to further understand differences in HBI synthesis in diatom communities living in different growth habitats.Item A 2540-year record of moisture variations derived from lacustrine sediment (Sasikul Lake) on the Pamir Plateau(Sage, 2014-05-06) Lei, Yanbin; Tian, Lide; Bird, Broxton W.; Hou, Juzhi; Ding, Lin; Oimahmadov, Ilhomjon; Gadoev, MustafoAlthough the Pamir Plateau is an ideal place to investigate paleo-environmental changes in the westerlies-dominated high Central Asia, there are only few Holocene records from this region. We present a sub-centennially resolved lacustrine record of moisture variations from Sasikul Lake, central Pamir Plateau, based on geochemical, sedimentological, and mineralogical proxies. Our results show that generally dry conditions at Sasikul Lake during the past 2540 years were interrupted by a pronounced wet period between ad 1550 and 1900, corresponding to the ‘Little Ice Age’ (LIA). More negative values of carbonate δ18O, lower total inorganic carbon (TIC), and sand content during LIA all indicate a relatively wet period with higher lake level. Higher TIC during the ‘Medieval Warm Period’ (MWP; ad 950–1200) reveals a lower lake level relative to the LIA. Low δ18O during this time is probably attributed to changes in the isotopic composition of input water and/or upstream moisture sources. The significant increase in detrital minerals and decrease in carbonate during the LIA provide further evidence for higher allochthonous input during the wet period at Sasikul Lake. The inferred moisture variations are consistent with existing records from regions of the northern Tibetan Plateau and Central Asia that are also influenced by the westerlies, but out-ofphase with those records from the Asian monsoon region, indicating that moisture variations at Sasikul Lake were mainly influenced by the strength and trajectories of the westerlies. The inferred water level at Sasikul Lake decreased significantly during the first half of the 20th century, and then increased in recent decades. This is consistent with the increase in lake area derived from satellite images and the monitoring data of large lake-level changes in Central Asia.Item Late Quaternary hydroclimate variability in the Colombian Andes and the potential for deep sediment core recovery at Lago de Tota revealed through CHIRP and airgun-sourced seismic reflection data(AGU, 2018-12) Gibson, Derek; Bird, Broxton W.; Watruss, Nigel; Escobar, Jaime; Lowell, Thomas V.; Ahmed, Maliha; Fonseca, Hector; Velasco, Felipe; Fernandez, Alejandro; Polissar, Pratigya J.A geophysical investigation of lacustrine stratigraphy at Lago de Tota (Tota), Boyaca, Colombia provides evidence for significant lake level fluctuations during the late Quaternary from ~60 ka to the present. CHIRP data collected in 2015 from this large, high-elevation lake in the Eastern Cordillera of the Northern Hemisphere (NH) Colombian Andes reveal a series of off-lap and on-lap sequences in the upper ~20 m of the lake’s sediment column that indicate large amplitude changes in lake level. These data, temporally constrained by 14C-dated sediment cores and extrapolated Holocene sedimentation rates, suggest that lake levels at Tota were lower than present during Marine Isotope Stage (MIS) 4 between 60 and 57 ka, relatively high during MIS 3 between 57 and 29 ka, fell to their lowest levels during MIS 2 between 29 and 14 ka, and gradually rose to the modern high-stand through a series of transgressions during MIS 1 and the Holocene from ~14 ka to the present. These fluctuations are broadly consistent with trends observed in other lake level reconstructions from the Northern (in phase) and Southern (out of phase) Hemisphere Andes, possibly supporting the idea that millennial-to-orbital-scale South American hydroclimate variability is linked to shifts in the mean latitude of the Intertropical Convergence Zone (ITCZ) due to the influence of insolation- and ocean circulation-driven hemispheric temperature gradients during glacial/stadial and interglacial/interstadial events. These results, as well as the presence of a thick (>300 m) sedimentary archive, indicate that Tota has significant potential to produce high-resolution, quantitative, paleo- hydroclimate data spanning much of the last 1 million years. Because geophysical surveys and long paleoclimate records from NH South America are exceedingly rare, these data provide critical insight into regional hydroclimate trends through the Late Quaternary.