Browsing by Author "Earth and Environmental Sciences, School of Science"
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Item A global synthesis of transpiration rate and evapotranspiration partitioning in the shrub ecosystems(Elsevier, 2022-03) Gao, Guangyao; Wang, Di; Zha, Tianshan; Wang, Lixin; Fu, Bojie; Earth and Environmental Sciences, School of ScienceTranspiration (T) is a fundamental process in understanding the ecophysiology of plants, and it is the dominant component of evapotranspiration (ET) in the terrestrial water cycle. Although previous studies have examined T characteristics of shrub ecosystems in some regions, global-scale synthesis that integrates the spatial variations of T, ET and ratio of T to ET (T/ET) and the associated influences of bio-/abiotic factors in the shrub ecosystems is currently lacking. In this study, we synthesized and analyzed T rate, ET rate and T/ET of the shrub ecosystems from the peer-reviewed articles using field observations around the world. These studies were mainly distributed in drylands with aridity index (ratio of precipitation to potential ET) < 0.65, which accounted for 86.4% of the study locations. Globally, the mean daily T and ET rates of shrubs were 1.5 ± 1.0 mm d−1 and 2.4 ± 0.8 mm d−1, with coefficient of variation of 63.2% and 36.2% among the study locations, respectively. Mean T/ET of the shrubs over the growing season was 0.54 ± 0.14, which was generally lower compared with forest, grassland and cropland ecosystems. The T rate of shrubs was positively related to shrub age, shrub height, leaf area index, and vegetation coverage (p < 0.05), and the effects of biotic factors on T rate were stronger compared with abiotic factors. The ET rate of shrubs was positively related to aridity index, long-term annual mean precipitation, mean soil water content, as well as shrub height and vegetation coverage (p < 0.05). By contrast, the effects of biotic factors on variations of shrub T/ET were weaker than those of abiotic factors, and the T/ET of shrubs was negatively related to aridity index, long-term annual mean precipitation and mean soil water content, but positively related to latitude (p < 0.05). This study is an important supplement of our knowledge gap in terrestrial water cycle, and the findings suggest that T accounted for about half of the water into atmosphere from shrub ecosystems, and the variations of T rate of shrubs were mainly controlled by biotic factors, whereas ET rate and T/ET was mainly affected by abiotic factors.Item A Landsat-derived annual inland water clarity dataset of China between 1984 and 2018(Copernicus, 2022-01-13) Tao, Hui; Song, Kaishan; Liu, Ge; Wang, Qiang; Wen, Zhidan; Jacinthe, Pierre-Andre; Xu, Xiaofeng; Du, Jia; Shang, Yingxin; Li, Sijia; Wang, Zongming; Lyu, Lili; Hou, Junbin; Wang, Xiang; Liu, Dong; Shi, Kun; Zhang, Baohua; Duan, Hongtao; Earth and Environmental Sciences, School of ScienceWater clarity serves as a sensitive tool for understanding the spatial pattern and historical trend in lakes' trophic status. Despite the wide availability of remotely sensed data, this metric has not been fully explored for long-term environmental monitoring. To this end, we utilized Landsat top-of-atmosphere reflectance products within Google Earth Engine in the period 1984–2018 to retrieve the average Secchi disk depth (SDD) for each lake in each year. Three SDD datasets were used for model calibration and validation from different field campaigns mainly conducted during 2004–2018. The red blue band ratio algorithm was applied to map SDD for lakes (>0.01 km2) based on the first SDD dataset, where R2=0.79 and relative RMSE (rRMSE) =61.9 %. The other two datasets were used to validate the temporal transferability of the SDD estimation model, which confirmed the stable performance of the model. The spatiotemporal dynamics of SDD were analyzed at the five lake regions and individual lake scales, and the average, changing trend, lake number and area, and spatial distribution of lake SDDs across China were presented. In 2018, we found the number of lakes with SDD <2 m accounted for the largest proportion (80.93 %) of the total lakes, but the total areas of lakes with SDD of <0.5 and >4 m were the largest, both accounting for about 24.00 % of the total lakes. During 1984–2018, lakes in the Tibetan–Qinghai Plateau region (TQR) had the clearest water with an average value of 3.32±0.38 m, while that in the northeastern region (NLR) exhibited the lowest SDD (mean 0.60±0.09 m). Among the 10 814 lakes with SDD results for more than 10 years, 55.42 % and 3.49 % of lakes experienced significant increasing and decreasing trends, respectively. At the five lake regions, except for the Inner Mongolia–Xinjiang region (MXR), more than half of the total lakes in every other region exhibited significant increasing trends. In the eastern region (ELR), NLR and Yungui Plateau region (YGR), almost more than 50 % of the lakes that displayed increase or decrease in SDD were mainly distributed in the area range of 0.01–1 km2, whereas those in the TQR and MXR were primarily concentrated in large lakes (>10 km2). Spatially, lakes located in the plateau regions generally exhibited higher SDD than those situated in the flat plain regions. The dataset is freely available at the National Tibetan Plateau Data Center (https://doi.org/10.11888/Hydro.tpdc.271571, Tao et al., 2021).Item A new, lower threshold for lead poisoning in children means more kids will get tested – but the ultimate solution is eliminating lead sources(The Conversation US, Inc., 2021-11-05) Filippelli, Gabriel; Earth and Environmental Sciences, School of ScienceItem A “Local First” Approach to Glacigenic Sediment Provenance Demonstrated Using U-Pb Detrital Zircon Geochronology of the Permo-Carboniferous Wynyard Formation, Tasmanian Basin(Society for Sedimentary Geology (SEPM), 2022) Ives, Libby R. W.; Isbell, John L.; Licht, Kathy J.; Earth and Environmental Sciences, School of ScienceWe propose that a “local first” approach should be applied to the interpretation of provenance indicators in glacigenic sediments of all depositional ages, especially where the glacier flow path is poorly constrained and the records of potential source lithologies are incomplete. Provenance proxies, specifically U-Pb detrital zircon geochronology, of glacigenic sediments are commonly used to infer the size and distribution of past ice centers, which are in turn used to inform ancient climate reconstructions. Interpretations of these proxies often assume that similar provenance signals between glacigenic units of the same depositional age are evidence that they were deposited by the same glacier, even when those units are, not infrequently, separated by thousands of kilometers. Though glaciers are capable of transporting sediment great distances, this assumption is problematic as it does not acknowledge observations from the geologic records of Pleistocene ice sheets that show provenance proxies in glacial sediments are most likely to reflect proximal (within 100 km) sediment sources located along a specific flow path. In a “local first” approach, provenance indicators are first compared to local source lithologies. If the indicator cannot be attributed to proximal sources, only then should progressively more distal sources be investigated. Applying a local first approach to sediment provenance in ancient glacial systems may result in significant revisions to paleo ice sheet reconstructions. The effectiveness of the local first approach is demonstrated here by comparing new U-Pb detrital zircon dates from the Permo-Carboniferous glacigenic Wynyard Fm with progressively distal source lithologies along the glacier’s inferred flow path. The Wynyard Fm and source lithologies were compared using an inverse Monte-Carlo unmixing model (DZMix). All measured Wynyard Fm detrital zircon dates can be attributed to zircon sources within 33 km of the sample location along the glacier’s flow path. This interpretation of a proximal detrital zircon provenance does not conflict with the popular interpretation made from sedimentological observations that the Wynyard Fm was deposited by a large, temperate outlet glacier or ice stream that flowed south-to-north across western Tasmania. Overall, a local first approach to glacial sediment provenance, though more challenging than direct comparisons between glacigenic sedimentary deposits, has the potential to elucidate the complex histories and flow paths of glacial sedimentary systems of all depositional ages.Item Ablation of Leptin Receptor Mediated Extracellular Regulated Kinase Activation Impairs Host Defense against Gram-Negative Pneumonia(Oxford University Press, 2012) Mancuso, Peter; Myers, Martin G., Jr.; Goel, Deepti; Serezani, Carlos H.; O’Brien, Edmund; Goldberg, Jared; Aronoff, David M.; Peters-Golden, Marc; Earth and Environmental Sciences, School of ScienceThe adipocyte-derived hormone leptin plays an important role in regulation of energy homeostasis and the innate immune response against bacterial infections. Leptin's actions are mediated by signaling events initiated by phosphorylation of tyrosine residues on the long form of the leptin receptor. We recently reported that disruption of leptin receptor-mediated STAT3 activation augmented host defense against pneumococcal pneumonia. In this report, we assessed leptin receptor-mediated ERK activation, a pathway that was ablated in the l/l mouse through a mutation of the tyrosine 985 residue in the leptin receptor, to determine its role in host defense against bacterial pneumonia in vivo and in alveolar macrophage (AM) antibacterial functions in vitro. l/l mice exhibited increased mortality and impaired pulmonary bacterial clearance after intratracheal challenge with Klebsiella pneumoniae. The synthesis of cysteinyl-leukotrienes was reduced and that of PGE(2) enhanced in AMs in vitro and the lungs of l/l mice after infection with K. pneumoniae in vivo. We also observed reduced phagocytosis and killing of K. pneumoniae in AMs from l/l mice that was associated with reduced reactive oxygen intermediate production in vitro. cAMP, known to suppress phagocytosis, bactericidal capacity, and reactive oxygen intermediate production, was also increased 2-fold in AMs from l/l mice. Pharmacologic blockade of PGE(2) synthesis reduced cAMP levels and overcame the defective phagocytosis and killing of bacteria in AMs from l/l mice in vitro. These results demonstrate that leptin receptor-mediated ERK activation plays an essential role in host defense against bacterial pneumonia and in leukocyte antibacterial effector functions.Item Amino-tethering synthesis strategy toward highly accessible sub-3-nm L10-PtM catalysts for high-power fuel cells(Elsevier, 2023-03) Gong, Qing; Zhang, Hong; Yu, Haoran; Jeon, Sunghu; Ren, Yang; Yang, Zhenzhen; Sun, Cheng-Jun; Stach, Eric A.; Foucher, Alexandre C.; Yu, Yikang; Smart, Matthew; Filippelli, Gabriel M.; Cullen, David A.; Liu, Ping; Xie, Jian; Earth and Environmental Sciences, School of ScienceBecause of the poor accessibility of embedded active sites, platinum (Pt)-based electrocatalysts suffer from insufficient Pt utilization and mass transport in membrane electrode assemblies (MEAs), limiting their performance in polymer electrolyte membrane fuel cells. Here, we report a simple and universal approach to depositing sub-3-nm L10-PtM nanoparticles over external surfaces of carbon supports through pore-tailored amino (NH2)-modification, which enables not only excellent activity for the oxygen reduction reaction, but also enhanced Pt utilization and mass transport in MEAs. Using a low loading of 0.10 mgPt·cm−2, the MEA of PtCo/KB-NH2 delivered an excellent mass activity of 0.691 A·mgPt−1, a record-high power density of 0.96 W·cm−2 at 0.67 V, and only a 30-mV drop at 0.80 A·cm−2 after 30,000 voltage cycles, which meets nearly all targets set by the Department of Energy. This work provides an efficient strategy for designing advanced Pt-based electrocatalysts and realizing high-power fuel cells.Item Annual Precipitation and Discharge Drive Increases in Escherichia Coli Concentrations in an Urban Stream(Elsevier, 2022) Li, Rui; Filippelli, Gabriel; Wang, Lixin; Earth and Environmental Sciences, School of ScienceDetermining climate change influences on E. coli dynamics in urban aquatic systems and predicting future E. coli changes are important to regulate water quality. In this study, data from 6985 measurements of E. coli from 1999-2019 in the Indianapolis, Indiana (USA) urban waterway Pleasant Run were analyzed by Mann-Kendall and multiple linear regression to examine long term trends in E. coli concentrations and loads, and to project E. coli concentrations under future climate change scenarios. E. coli concentrations and loads monotonically increased over the last two decades, with E. coli concentrations increasing from 111 MPN/100 mL in 1999 to 911 MPN/100 mL in 2019. E. coli loads increased from 5×10 12 MPN/year to 90×10 12 MPN/year over the same period. E. coli showed peak concentration in summer, and significantly higher concentration in sites with Combined Sewer Outfalls relative to those without. Precipitation had both direct and indirect impacts on E. coli concentrations, meditated by stream discharge. Multiple linear regression results showed annual precipitation and discharge accounted for 60% of E. coli concentration variations. Based on the observed precipitation-discharge- E. coli concentration relationship, the projection results showed that, in the highest emission RCP 8.5 climate scenario, E. coli concentrations in 2020s, 2050s, and 2080s will be 1350 MPN/100mL, 1386 MPN/100mL, and 1443 MPN/100mL, respectively.Item Appearance of an enigmatic Pb source in South America around 2000 BP: Anthropogenic vs natural origin(Elsevier, 2020-05) Kamenov, George D.; Escobar, Jaime; Arnold, T. Elliott; Pardo-Trujillo, Andrés; Gangoiti, Gotzon; Hoyos, Natalia; Curtis, Jason H.; Bird, Broxton W.; Velez, Maria Isabel; Vallejo, Felipe; Trejos-Tamayo, Raul; Earth and Environmental Sciences, School of ScienceNeotropical wetlands in the paramo (a unique alpine-tundra ecosystem) region of South America have the potential to be natural archives for metal pollution by modern and past populations. An organic-rich sediment core from the El Triunfo mire, located in the paramo region, provides a record of natural and anthropogenic metal sources in the Northern Andes during the last four millennia. The Triunfo record is complex, as the mire is located in the Northern Volcanic Zone (NVZ) and receives direct input of volcanic material. Regardless of the volcanic input, calculated metal enrichment factors normalized to Sc show metal enrichment in the Northern Andes around 2000 years ago and again in recent industrial times. A number of samples show a shift to lower Pb isotope ratios indicating the appearance of a new, enigmatic Pb source around 2000 years ago. The topmost layer of the core shows the lowest Pb isotope ratios, reflecting input of modern anthropogenic Pb. In contrast to Pb, Nd isotopes do not show significant variations along the entire core, indicating mostly volcanic material input to the mire. The decoupling between Nd and Pb isotopes indicates that the enigmatic Pb source must be anthropogenic in origin. Based on the dominant atmospheric currents in the region, the El Triunfo mire can receive input from long-distance and local sources. Dispersion simulations validate the possibility of pollutant particle transport from Europe to the northern hemisphere Neotropics. As the first metal enrichment coincides with the Roman Empire times, the El Triunfo Pb isotopes are compared to contemporary peat records from Europe. All records show similar decrease in the Pb isotope ratios due to anthropogenic Pb input. Small Pb isotope differences between a record from Spain and El Triunfo indicate that the enigmatic Pb that appeared around 2000 years ago in the mire is unlikely to have originated from long-distance Roman Empire pollution. Instead, a group of deposits, namely San Lucas, San Martin de Loba, and El Bagre, located in north-central Colombia, show low Pb isotope ratios that can potentially explain the observed Pb signal in the El Triunfo sediments. The deposits are located up wind, along the predominant atmospheric currents in the region. Therefore, it is plausible that mining activities in the area of San-Lucas, San-Martin, and/or El Bagre released Pb in the atmosphere that was transported and deposited in the El Triunfo mire. These deposits are not associated with the known regions of influence of any of the early pre-Hispanic cultures in Colombia and there is no evidence for mining in this region around 2000 years ago. However, given that all other possibilities are unlikely, the appearance of lower Pb isotope ratios in the mire suggests the onset of mining in the region at least 400 years earlier than the available archaeological evidence at present. The El Triunfo mire record can be used as indirect evidence for significant metal exploitation by early pre-Hispanic cultures in the northern Andes as early as 2000 years ago.Item Application of Scenario Earthquakes for Analysis of Seismically Triggered Landslide Hazard: A Case Study in Costa Rica(Central American School of Geology, University of Costa Rica, 2022-07-11) Seal , Dylan M.; Nowicki Jessee, M. Anna; Hamburger, Michael W.; Ruiz , Paulo; Earth and Environmental Sciences, School of ScienceIn this study, we demonstrate the capabilities of hypothetical scenario earthquakes as a new tool for assessment of hazards associated with earthquake-triggered landslides. Costa Rica offers an ideal environment for demonstrating the utility of scenario earthquakes due to its diverse tectonic environments and associated widespread seismic hazard, rugged topography, and high landslide susceptibility. We investigate the relative influence of landslide proxies such as topographic slope, peak ground velocity (PGV), and compound topographic index (CTI), and earthquake source parameters such as magnitude and depth, on predicted landslide probability and fatality. We examine five distinct tectonic environments, including subduction events beneath the (1) Nicoya and (2) Osa peninsulas respectively, (3) intraplate earthquakes beneath the Central Volcanic Range (CVR) and (4) the Central Costa Rica Deformed Belt (CCRDB), and (5) back-arc thrust events on the eastern Caribbean coast. Our results demonstrate that the slope, PGV, and CTI thresholds necessary to produce landslide probabilities greater than 10% vary by tectonic environment. In all cases, we observe magnitude to be the primary control on the predicted maximum landslide probability and overall areal landslide coverage. We validate model predictions with observed landslide inventories from the 2009 Cinchona and 1991 Limon earthquakes, demonstrating a good fit, where over 70% of landslides occurring in zones of greater than 20% probability. We also use a global model of landslide impact to predict exposure and fatality ranges for each scenario earthquake of this study, revealing that moderate-sized earthquakes in the CCRDB and CVR and large subduction megathrust earthquakes each pose a significant hazard to Costa Rica’s population.Item Assessing Unequal Airborne Exposure to Lead Associated With Race in the USA(Wiley, 2023-07-24) Laidlaw, Mark A. S.; Mielke, Howard W.; Filippelli, Gabriel M.; Earth and Environmental Sciences, School of ScienceRecent research applied the United States Environmental Protection Agency's Chemical Speciation Network and Interagency Monitoring of Protected Visual Environments monitoring stations and observed that mean concentrations of atmospheric lead (Pb) in highly segregated counties are a factor of 5 higher than in well‐integrated counties and argument is made that regulation of existing airborne Pb emissions will reduce children's Pb exposure. We argue that one of the main sources of children's current Pb exposure is from resuspension of legacy Pb in soil dust and that the racial disparity of Pb exposure is associated with Pb‐contaminated community soils.