A 2500 Year Lake Sediment Record of Drought and Human Activity From Southwestern China

The delivery of precipitation to southwestern China is largely through monsoon circulation which has evolved with changing insolation forcing during the Holocene and will likely continue to change in response to greenhouse gas increases. Additionally, southwestern China has a long history of human activity including mining, metallurgy, agriculture, and pollution. Here, high-resolution sampling of a sediment core from Lake Xing Yun in the Yunnan Province (24°10'N, 102°46'E), a drought sensitive lake that behaves as a closed basin, provides a sub-decadal record of changing climate and human activity in the late Holocene. We use δ18O and δ13C measurements of authigenic carbonate precipitated from the lake water and magnetic susceptibility values to document the timing, direction, and magnitude of moisture changes associated with variations in monsoon strength. We use δ13C and δ15N measurements on organic matter and carbon to nitrogen ratios to assess the impact of human activity on the Xing Yun watershed and sediment trace metal concentrations in investigate regional mining and smelting intensity.The 2,500 year record highlights several transition periods related to both human and climate forcing. The rise of metallurgy and intensive mining practices occurs at 900 AD, much later than historical records indicate. A number of proxies including δ13C values and C/N ratio show a marked shift at 1600 AD, the time in which many Han immigrants from the north settled and worked the land in the Yunnan Province. The most pronounced feature of the record is a rapid transition to a substantially drier climate that took place over 50 years and persisted from 1360-1880 AD as an expression of the Little Ice Age (LIA). This project demonstrates that complex human and climate interactions have been taking place for thousands of years and have the potential to illuminate discontinuities in Chinese historical records and learn lessons that might apply to future climate change

Severe Little Ice Age drought in the midcontinental United States during the Mississippian abandonment of Cahokia

Drought has long been suspected as playing an important role in the abandonment of pre-Columbian Native American settlements across the midcontinental United States between 1350 and 1450 CE. However, high-resolution paleoclimatic reconstructions reflecting local effective moisture (the ratio of precipitation to evaporation) that are located in proximity to Mississippi period (1050–1450 CE) population centers are lacking. Here, we present a 1600-year-long decadally resolved oxygen isotope (δ18O) record from Horseshoe Lake (Collinsville, IL), an evaporatively influenced oxbow lake that is centrally located within the largest and mostly densely populated series of Mississippian settlements known as Greater Cahokia. A shift to higher δ18O in the Horseshoe Lake sediment record from 1200 to 1400 CE indicates that strongly evaporative conditions (i.e., low effective moisture) were persistent during the leadup to Cahokia’s abandonment. These results support the hypothesis that climate, and drought specifically, strongly impacted agriculturally based pre-Columbian Native American cultures in the midcontinental US and highlights the susceptibility of this region, presently a global food production center, to hydroclimate extremes

Regionally consistent Western North America paleomagnetic directions from 15 to 35 ka: Assessing chronology and uncertainty with paleosecular variation (PSV) stratigraphy

New Paleomagnetic Secular Variation (PSV) data from Fish Lake, Utah, USA, along with previously published regional records, allow us to build an independently dated Western North America PSV stack (WNAM17) from about 35 to 15 ka that quantifies dating and paleomagnetic uncertainties. In February 2014, we recovered a composite 11-m-long sediment record from Fish Lake, Utah that retrieved glacially influenced and post-glacial sediments. Computed tomography (CT) scans and magnetic susceptibility were used to build a precise depth scale, while radiocarbon dating of terrestrial macrofossils and tephrostratigraphy provide tight age-control. Glacially influenced sediments have well-defined characteristic remanent magnetizations with all maximum angular deviation values < 5 degrees, resolving a record of Late Pleistocene PSV. Comparison to the PSV records at Bear Lake, Utah/Idaho, USA and Bessette Creak, British Columbia, Canada, which also contain terrestrial material radiocarbon age-control points, allow us to develop the WNAM17 PSV stack which considers both dating and magnetic acquisition uncertainties. We utilize a regional PSV chronostratigraphic modeling approach to assign chronology and uncertainty to the PSV signal and to evaluate the fidelity of age-control points at the site level that are difficult to objectively evaluate otherwise. The greatest strength of our age-depth model is that by approaching chronostratigraphy from a regional perspective, assuming a common geomagnetic signal, we can address sources of geologic uncertainty that would be difficult to quantify using only one site. We illustrate the potential stratigraphic opportunities using the WNAM17 PSV template through assessing the timing of paleoenvironmental and paleomagnetic events in Western North America, including the timing of glaciations in the Fish Lake and Bear Lake catchments and the stratigraphic context for the Late Pleistocene geomagnetic excursion recorded at Mono Lake. (C) 2018 Elsevier Ltd. All rights reserved

700,000 years of tropical Andean glaciation

Open Access This article is licensed under a Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made. The images or other third party material in this article are included in the article’s Creative Commons license, unless indicated otherwise in a credit line to the material. If material is not included in the article’s Creative Commons license and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this license, visit http://creativecommons.org/licenses/by/4.0/.Our understanding of the climatic teleconnections that drove ice-age cycles has been limited by a paucity of well-dated tropical records of glaciation that span several glacial–interglacial intervals. Glacial deposits offer discrete snapshots of glacier extent but cannot provide the continuous records required for detailed interhemispheric comparisons. By contrast, lakes located within glaciated catchments can provide continuous archives of upstream glacial activity, but few such records extend beyond the last glacial cycle. Here a piston core from Lake Junín in the uppermost Amazon basin provides the first, to our knowledge, continuous, independently dated archive of tropical glaciation spanning 700,000 years. We find that tropical glaciers tracked changes in global ice volume and followed a clear approximately 100,000-year periodicity. An enhancement in the extent of tropical Andean glaciers relative to global ice volume occurred between 200,000 and 400,000 years ago, during sustained intervals of regionally elevated hydrologic balance that modified the regular approximately 23,000-year pacing of monsoon-driven precipitation. Millennial-scale variations in the extent of tropical Andean glaciers during the last glacial cycle were driven by variations in regional monsoon strength that were linked to temperature perturbations in Greenland ice cores1; these interhemispheric connections may have existed during previous glacial cycles.This research was supported by grants from the ICDP (02-2012) and from the US National Science Foundation (D.T.R., EAR-1402076; M.B.A., EAR-1404113; J.S.S., EAR-1400903; D.M., EAR-1404414; M.B., EAR-1402054).Peer reviewe

Sediment delivery and lake dynamics in a Mediterranean mountain watershed: Human-climate interactions during the last millennium (El Tobar Lake record, Iberian Range, Spain)

Land degradation and soil erosion are key environmental problems in Mediterranean mountains characterized by a long history of human occupation and a strong variability of hydrological regimes. To assess recent trends and evaluate climatic and anthropogenic impacts in these highly human modified watersheds we apply an historical approach combining lake sediment core multi-proxy analyses and reconstructions of past land uses to El Tobar Lake watershed, located in the Iberian Range (Central Spain). Four main periods of increased sediment delivery have been identified in the 8 m long sediment sequence by their depositional and geochemical signatures. They took place around 16th, late 18th, mid 19th and early 20th centuries as a result of large land uses changes such as forest clearing, farming and grazing during periods of increasing population. In this highly human-modified watershed, positive synergies between human impact and humid periods led to increased sediment delivery periods. During the last millennium, the lake depositional and geochemical cycles recovered quickly after each sediment delivery event, showing strong resilience of the lacustrine system to watershed disturbance. Recent changes are characterized by large hydrological affections since 1967 with the construction of a canal from a nearby reservoir and a decreased in anthropic pressure in the watershed as rural areas were abandoned. The increased fresh water influx to the lake has caused large biological changes, leading to stronger meromictic conditions and higher organic matter accumulation while terrigenous inputs have decreased. Degradation processes in Iberian Range watersheds are strongly controlled by anthropic activities (land use changes, soil erosion) but modulated by climate-related hydrological changes (water availability, flood and runoff frequency).We want to thank D. Schnurenberger, A. Norens and M. Shapley (Limnological Research Center) for the 2004 field expedition to collect the cores, and the Regional Government (Junta de Comunidades de Castilla–La Mancha) for logistic support. Initial Core Descriptions were performed at the CoreLab (University of Minnesota). F. Burjachs kindly provided pollen data from Lake La Cruz sequence and P. González-Sampériz helped with vegetation dynamics interpretations. S. Vicente nicely provided and elaborated the data from the weather stations. A. Navas and T. Lopez provided quickly the last-minute grain-size analysis.We also thank the numerous colleagues involved in the field campaigns to recover the cores, the LRC,LLO and the University of Pittsburgh staff, and IPE-CSIC laboratory services. Authors would also like to acknowledge the helpful comments made by reviewers. This research has been supported by the GLOBALKARST (CGL2009-08415) and GRACCIE — ConsoliderCSD2007-00067 projects funded by the Spanish Ministry of Economy and Competitiveness and by the I-LINK programme(I-LINK0510) funded by the CSIC. F. Barreiro and M. Morellón hold ‘JAE-PreDoc’ and ‘JAE-Doc’ pre and postdoctoral contracts respectively, both co-funded by C.S.I.C. and the European Social Fund.Peer reviewe

Human impact of biogeochemical cycles and deposition dynamics in karstic lakes: El Tobar lake record (Central Iberian Range, Spain)

Poster presentado en la Reunión de la American Geophysical Union, celebrada San Francisco (EEUU), del 15 al 19 de Diciembre de 2014Peer reviewe

Environmental Legacy of Copper Metallurgy and Mongol Silver Smelting Recorded in Yunnan Lake Sediments

Geochemical measurements on well-dated sediment cores from Lake Er (Erhai) are used to determine the timing of changes in metal concentrations over 4500 years in Yunnan, a borderland region in southwestern China noted for rich mineral deposits but with inadequately documented metallurgical history. Our findings add new insight into the impacts and environmental legacy of human exploitation of metal resources in Yunnan history. We observe an increase in copper at 1500 BC resulting from atmospheric emissions associated with metallurgy. These data clarify the chronological issues related to links between the onset of Yunnan metallurgy and the advent of bronze technology in adjacent Southeast Asia, subjects that have been debated for nearly half a century. We also observe an increase from 1100 to 1300 AD in a number of heavy metals including lead, silver, zinc, and cadmium from atmospheric emissions associated with silver smelting. Culminating during the rule of the Mongols, known as the Yuan Dynasty (1271–1368 AD), these metal concentrations approach levels three to four times higher than those from industrialized mining activity occurring within the catchment today. Notably, the concentrations of lead approach levels at which harmful effects may be observed in aquatic organisms. The persistence of this lead pollution over time created an environmental legacy that likely contributes to known issues in modern day sediment quality. We demonstrate that historic metallurgical production in Yunnan can cause substantial impacts on the sediment quality of lake systems, similar to other paleolimnological findings around the globe

Lead isotope fingerprinting techniques help identify and quantify 3000 years of atmospheric lead pollution from Laguna Roya, northwestern Iberia

Legacy pollution research has established that over the past 3000 years, mining and metallurgical activities have resulted in widespread deposition of lead (Pb) pollution. However, there is still a limited understanding of how humans have impacted the long-term cycling of Pb in the environment. We present a 4,000-year lake sediment Pb isotope record from Laguna Roya, northwestern Iberia, that identifies and quantifies the predominant sources of atmospheric Pb pollution. For the first time, Pb isotopic compositions of ancient slag samples dated (∼600 BCE–200 CE) from a mining district in the southwest of the Iberian Peninsula are compared to Pb isotope ratios of Pb pollution deposited contemporaneously in lake sediments. In addition, literature Pb isotope ratios of ores from mining regions throughout Iberia are compared with those of leaded gasoline and coal to identify additional sources of anthropogenic Pb. Deposition of atmospheric Pb pollution begins after 950 BCE, and until 1750 CE, the Pb isotopic composition most resembles the southwestern slag deposits, containing a mixture of Pb ores from southeast Iberia (up to 36%) and southwest Iberia (∼74%). Between 1750 and 1960 CE, Pb pollution is atLegacy pollution research has established that over the past 3000 years, mining and metallurgical activities have resulted in widespread deposition of lead (Pb) pollution. However, there is still a limited understanding of how humans have impacted the long-term cycling of Pb in the environment. We present a 4,000-year lake sediment Pb isotope record from Laguna Roya, northwestern Iberia, that identifies and quantifies the predominant sources of atmospheric Pb pollution. For the first time, Pb isotopic compositions of ancient slag samples dated (∼600 BCE–200 CE) from a mining district in the southwest of the Iberian Peninsula are compared to Pb isotope ratios of Pb pollution deposited contemporaneously in lake sediments. In addition, literature Pb isotope ratios of ores from mining regions throughout Iberia are compared with those of leaded gasoline and coal to identify additional sources of anthropogenic Pb. Deposition of atmospheric Pb pollution begins after 950 BCE, and until 1750 CE, the Pb isotopic composition most resembles the southwestern slag deposits, containing a mixture of Pb ores from southeast Iberia (up to 36%) and southwest Iberia (∼74%). Between 1750 and 1960 CE, Pb pollution is attributed to PbLegacy pollution research has established that over the past 3000 years, mining and metallurgical activities have resulted in widespread deposition of lead (Pb) pollution. However, there is still a limited understanding of how humans have impacted the long-term cycling of Pb in the environment. We present a 4,000-year lake sediment Pb isotope record from Laguna Roya, northwestern Iberia, that identifies and quantifies the predominant sources of atmospheric Pb pollution. For the first time, Pb isotopic compositions of ancient slag samples dated (∼600 BCE–200 CE) from a mining district in the southwest of the Iberian Peninsula are compared to Pb isotope ratios of Pb pollution deposited contemporaneously in lake sediments. In addition, literature Pb isotope ratios of ores from mining regions throughout Iberia are compared with those of leaded gasoline and coal to identify additional sources of anthropogenic Pb. Deposition of atmospheric Pb pollution begins after 950 BCE, and until 1750 CE, the Pb isotopic composition most resembles the southwestern slag deposits, containing a mixture of Pb ores from southeast Iberia (up to 36%) and southwest Iberia (∼74%). Between 1750 and 1960 CE, Pb pollution is attributed to Pb mining in southcentral Iberia. After 1960 CE, the dominant Pb pollution source (∼85%) is again metal refining in southwestern Iberia, and only ∼15% is from leaded gasoline. Provenance and reconstruction of the temporal and spatial distribution of legacy Pb pollution further our understanding of how humans have affected the biogeochemical cycle of this toxic element in the environment over time. mining in southcentral Iberia. After 1960 CE, the dominant Pb pollution source (∼85%) is again metal refining in southwestern Iberia, and only ∼15% is from leaded gasoline. Provenance and reconstruction of the temporal and spatial distribution of legacy Pb pollution further our understanding of how humans have affected the biogeochemical cycle of this toxic element in the environment over time.tributed to Pb mining in southcentral Iberia. After 1960 CE, the dominant Pb pollution source (∼85%) is again metal refining in southwestern Iberia, and only ∼15% is from leaded gasoline. Provenance and reconstruction of the temporal and spatial distribution of legacy Pb pollution further our understanding of how humans have affected the biogeochemical cycle of this toxic element in the environment over time.Hewlett FoundationUniversity of Pittsburgh International Studies FundCSIC I-Link programMinisterio de Econmía y CompetitividadDepto. de Geodinámica, Estratigrafía y PaleontologíaFac. de Ciencias GeológicasTRUEpu

Distinct spatial immune microlandscapes are independently associated with outcomes in triple-negative breast cancer

The utility of spatial immunobiomarker quantitation in prognostication and therapeutic prediction is actively being investigated in triple-negative breast cancer (TNBC). Here, with high-plex quantitative digital spatial profiling, we map and quantitate intraepithelial and adjacent stromal tumor immune protein microenvironments in systemic treatment-naive (female only) TNBC to assess the spatial context in immunobiomarker-based prediction of outcome. Immune protein profiles of CD45-rich and CD68-rich stromal microenvironments differ significantly. While they typically mirror adjacent, intraepithelial microenvironments, this is not uniformly true. In two TNBC cohorts, intraepithelial CD40 or HLA-DR enrichment associates with better outcomes, independently of stromal immune protein profiles or stromal TILs and other established prognostic variables. In contrast, intraepithelial or stromal microenvironment enrichment with IDO1 associates with improved survival irrespective of its spatial location. Antigen-presenting and T-cell activation states are inferred from eigenprotein scores. Such scores within the intraepithelial compartment interact with PD-L1 and IDO1 in ways that suggest prognostic and/or therapeutic potential. This characterization of the intrinsic spatial immunobiology of treatment-naive TNBC highlights the importance of spatial microenvironments for biomarker quantitation to resolve intrinsic prognostic and predictive immune features and ultimately inform therapeutic strategies for clinically actionable immune biomarkers.The tumor immune microenvironment is an important determinant of clinical outcomes and therapeutic responses in patients with triple-negative breast cancer (TNBC). Here the authors perform digital spatial profiling of tumor tissues to characterize the spatial immunobiology of treatment-naive TNBC.Peer reviewe