South China Sea hydrological changes and Pacific Walker Circulation variations over the last millennium

© Macmillan Publishers Limited, 2011. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in Nature Communications 2 (2011): 293, doi:10.1038/ncomms1297.The relative importance of north–south migrations of the intertropical convergence zone (ITCZ) versus El Niño-Southern Oscillation and its associated Pacific Walker Circulation (PWC) variability for past hydrological change in the western tropical Pacific is unclear. Here we show that north–south ITCZ migration was not the only mechanism of tropical Pacific hydrologic variability during the last millennium, and that PWC variability profoundly influenced tropical Pacific hydrology. We present hydrological reconstructions from Cattle Pond, Dongdao Island of the South China Sea, where multi-decadal rainfall and downcore grain size variations are correlated to the Southern Oscillation Index during the instrumental era. Our downcore grain size reconstructions indicate that this site received less precipitation during relatively warm periods, AD 1000–1400 and AD 1850–2000, compared with the cool period (AD 1400–1850). Including our new reconstructions in a synthesis of tropical Pacific records results in a spatial pattern of hydrologic variability that implicates the PWC.This work was supported by the Natural Science Foundation of China (NSFC) (40730107) and the Major State Basic Research Development Program of China (973 Program) (No.2010CB428902). DWO acknowledges support from the US NSF

Climate Change in Lowland Central America During the Late Deglacial and Early Holocene

The transition from arid glacial to moist early Holocene conditions represented a profound change in northern lowland Neotropical climate. Here we report a detailed record of changes in moisture availability during the latter part of this transition ({approx}11,250 to 7,500 cal yr BP) inferred from sediment cores retrieved in Lake Peten Itza, northern Guatemala. Pollen assemblages demonstrate that a mesic forest had been largely established by {approx}11,250 cal yr BP, but sediment properties indicate that lake level was more than 35 m below modern stage. From 11,250 to 10,350 cal yr BP, during the Preboreal period, lithologic changes in sediments from deep-water cores (>50 m below modern water level) indicate several wet-dry cycles that suggest distinct changes in effective moisture. Four dry events (designated PBE1-4) occurred at 11,200, 10,900, 10,700, and 10,400 cal yr BP and correlate with similar variability observed in the Cariaco Basin titanium record and glacial meltwater pulses into the Gulf of Mexico. After 10,350 cal yr BP, multiple sediment proxies suggest a shift to a more persistently moist early Holocene climate. Comparison of results from Lake Peten Itza with other records from the circum-Caribbean demonstrates a coherent climate response during the entire span of our record. Furthermore, lowland Neotropical climate during the late deglacial and early Holocene period appears to be tightly linked to climate change in the high-latitude North Atlantic. We speculate that the observed changes in lowland Neotropical precipitation were related to the intensity of the annual cycle and associated displacements in the mean latitudinal position of the Intertropical Convergence Zone and Azores-Bermuda high-pressure system. This mechanism operated on millennial-to-submillennial timescales and may have responded to changes in solar radiation, glacial meltwater, North Atlantic sea ice, and the Atlantic meridional overturning circulation (MOC)

Mast Cell Diseases in Practice and Research: Issues and Perspectives Raised by Patients and Their Recommendations to the Scientific Community and Beyond

Background: Since 2010, patients and physicians have collaborated to understand unmet needs of patients with mast cell diseases, incorporating mastocytosis and mast cell activation disorders, which include mast cell activation syndromes. Objective: This Open Innovation in Science project aims to expand understanding of the needs of patients affected by mast cell diseases, and encourage global communication among patient advocacy groups, physicians, researchers, industry, and government. A major aim is to support the scientific community's efforts to improve diagnosis, management, therapy, and patients’ quality of life by addressing unmet needs. Methods: In collaboration with mast cell disease specialists, 13 patient advocacy groups from 12 countries and regions developed lists of top patient needs. A core team of leaders from patient advocacy groups collected and analyzed the data and proposed possible actions to address patient needs. Results: Findings identified similarities and differences among participating countries in unmet needs between patients with mastocytosis and those with mast cell activation syndromes. Issues emphasized struggles relating to the nature and rarity of mast cell diseases, their impact on quality of life, the diagnostic process, access to appropriate care, more effective treatment, and the need for research. Conclusions: Solutions vary across countries because situations differ, in particular regarding the existence of and access to centers of excellence and reference centers. Multifaceted mast cell activation syndrome barriers necessitate innovative approaches to improve access to appropriate care. The outcomes of this project should greatly support scientists and clinicians in their efforts to improve diagnosis, management, and treatment of patients with mastocytosis and mast cell activation disorders.The authors thank Tania Bray, Jan Hempstead, Heather Mayne, Joanne Mulder-Brambleby, and Irene Wilson for their supporting contributions, and all patients and families affected by MCDs, who shared their needs and concerns for development of this project. Authors involved in study conception and design were P. Valent, S.V. Jennings, C.C. Finnerty, J.S. Hobart, M. Martín-Martínez, K.A. Sinclair, V.M. Slee, J. Agopian, C. Akin, I. Álvarez-Twose, P. Bonadonna, A.A. Bowman, K. Brockow, H. Bumbea, C. de Haro, J.S. Fok, K. Hartmann, N. Hegmann, O. Hermine, M. Kalisiak, C.H. Katelaris, J. Kurz, P. Marcis, D. Mayne, D. Mendoza, A. Moussy, G. Mudretzkyj, N. Nidelea Vaia, M. Niedoszytko, H. Oude Elberink, A. Orfao, D.H. Radia, S. Rosenmeier, E. Ribada, W. Schinhofen, J. Schwaab, F. Siebenhaar, M. Triggiani, G. Tripodo, R. Velazquez, Y. Wielink, F. Wimazal, T. Yigit, and C. Zubrinich. Authors involved in acquisition and review of data were S.V. Jennings, C.C. Finnerty, J.S. Hobart, M. Martín-Martínez, K.A. Sinclair, V.M. Slee, J. Agopian, C. Akin, I. Álvarez-Twose, P. Bonadonna, A.A. Bowman, K. Brockow, H. Bumbea, C. de Haro, J.S. Fok, K. Hartmann, N. Hegmann, O. Hermine, M. Kalisiak, C.H. Katelaris, J. Kurz, P. Marcis, D. Mayne, D. Mendoza, A. Moussy, G. Mudretzkyj, N. Nidelea Vaia, M. Niedoszytko, H. Oude Elberink, A. Orfao, D.H. Radia, S. Rosenmeier, E. Ribada, W. Schinhofen, J. Schwaab, F. Siebenhaar, M. Triggiani, G. Tripodo, R. Velazquez, Y. Wielink, F. Wimazal, T. Yigit, C. Zubrinich, and P. Valent. The Core Group (analysis and interpretation of data and drafting of the manuscript) include S.V. Jennings, C.C. Finnerty, J.S. Hobart, M. Martín-Martínez, K.A. Sinclair, and V.M. Slee. Critical revision was performed by S.V. Jennings, C.C. Finnerty, J.S. Hobart, M. Martín-Martínez, K.A. Sinclair, V.M. Slee, J. Agopian, C. Akin, I. Álvarez-Twose, P. Bonadonna, A.A. Bowman, K. Brockow, H. Bumbea, C. de Haro, J.S. Fok, K. Hartmann, N. Hegmann, O. Hermine, M. Kalisiak, C.H. Katelaris, J. Kurz, P. Marcis, D. Mayne, D. Mendoza, A. Moussy, G. Mudretzkyj, N. Nidelea Vaia, M. Niedoszytko, H. Oude Elberink, A. Orfao, D.H. Radia, S. Rosenmeier, E. Ribada, W. Schinhofen, J. Schwaab, F. Siebenhaar, M. Triggiani, G. Tripodo, R. Velazquez, Y. Wielink, F Wimazal, T. Yigit, C. Zubrinich, and P. Valent

Mast Cell Diseases in Practice and Research:Issues and Perspectives Raised by Patients and Their Recommendations to the Scientific Community and Beyond

Background: Since 2010, patients and physicians have collaborated to understand unmet needs of patients with mast cell diseases, incorporating mastocytosis and mast cell activation disorders, which include mast cell activation syndromes. Objective: This Open Innovation in Science project aims to expand understanding of the needs of patients affected by mast cell diseases, and encourage global communication among patient advocacy groups, physicians, researchers, industry, and government. A major aim is to support the scientific community's efforts to improve diagnosis, management, therapy, and patients’ quality of life by addressing unmet needs. Methods: In collaboration with mast cell disease specialists, 13 patient advocacy groups from 12 countries and regions developed lists of top patient needs. A core team of leaders from patient advocacy groups collected and analyzed the data and proposed possible actions to address patient needs. Results: Findings identified similarities and differences among participating countries in unmet needs between patients with mastocytosis and those with mast cell activation syndromes. Issues emphasized struggles relating to the nature and rarity of mast cell diseases, their impact on quality of life, the diagnostic process, access to appropriate care, more effective treatment, and the need for research. Conclusions: Solutions vary across countries because situations differ, in particular regarding the existence of and access to centers of excellence and reference centers. Multifaceted mast cell activation syndrome barriers necessitate innovative approaches to improve access to appropriate care. The outcomes of this project should greatly support scientists and clinicians in their efforts to improve diagnosis, management, and treatment of patients with mastocytosis and mast cell activation disorders

Climate change in lowland Central America during the late deglacial and early Holocene

The transition from arid glacial to moist early Holocene conditions represented a profound change in northern lowland Neotropical climate. Here we report a detailed record of changes in moisture availability during the latter part of this transition (11 250 to 7500 cal. yr BP) inferred from sediment cores retrieved in Lake Pete´n Itza´, northern Guatemala. Pollen assemblages demonstrate that a mesic forest had been largely established by 11 250 cal. yr BP, but sediment properties indicate that lake level was more than 35m below modern stage. From 11 250 to 10 350 cal. yr BP,during the Preboreal period, lithologic changes in sediments from deep-water cores (>50m below modern water level) indicate several wet–dry cycles that suggest distinct changes in effective moisture. Four dry events (designated PBE1-4) occurred centred at 11 200, 10 900, 10 700 and 10 400 cal. yr BP and correlate with similar variability observed in the Cariaco Basin titanium record and glacial meltwater pulses into the Gulf of Mexico. After 10 350 cal. yr BP, multiple sediment proxies suggest a shift to a more persistently moist early Holocene climate. Comparison of results from Lake Pete´n Itza´ with other records from the circum-Caribbean demonstrates a coherent climate response during the entire span of our record. Furthermore, lowland Neotropical climate during the late deglacial and early Holocene period appears to be tightly linked to climate change in the highlatitude North Atlantic. We speculate that the observed changes in lowland Neotropical precipitation were related to the intensity of the annual cycle and associated displacements in the mean latitudinal position of the Intertropical Convergence Zone and Azores–Bermuda high-pressure system. This mechanism operated on millennial-to-submillennial timescales and may have responded to changes in solar radiation, glacial meltwater, North Atlantic sea ice, and the Atlantic meridional overturning circulatio

Quantification of soil erosion rates related to ancient Maya deforestation

We used seismic and sediment core data to quantify soil erosion rates for the past ~6000 yr in the closed catchment of Lake Salpetén, in the tropical lowlands of northern Guatemala. The region was affected by ancient Maya land use from before ca. 1000 B.C. to A.D. 900. This period of human impact coincided with deposition in the lake of a detrital unit (Maya Clay) as much as 7 m thick that contrasts sharply with the relatively organic-rich gyttja deposited both before and after Maya occupation of the watershed. The greatest soil loss, with mean sustained values of ~1000 t/km2yr–1, occurred in the Middle and Late Preclassic Periods (700 B.C. to A.D. 250), associated with relatively low Maya population densities. Soil erosion slowed during the period of maximum population density in the Late Classic Period (A.D. 550–830), indicating a decoupling between human population density and soil erosion rate. The most rapid soil loss occurred early during initial land clearance, suggesting that even low numbers of people can have profound impacts on lowland tropical karst landscapes

Recent eutrophication in the southern basin of Lake Peten Itza, Guatemala: Human impact on a large tropical lake.

A 210Pb-dated sediment core from a small bay in the southern basin of Lake Petén Itzá, Guatemala documents recent cultural eutrophication. Increased sediment accumulation beginning ∼1930 A.D. coincided with catchment population growth and was a consequence of watershed deforestation and increased surface run-off. At the same time, geochemical records from the Lake Petén Itzá sediment core indicate increased phosphorus loading and organic matter accumulation. High nutrient concentrations after 1965 A.D. coincided with lower sediment C/N ratios, suggesting an increase in the relative contribution of phytoplankton to the organic matter pool. This inference is confirmed by the dominance of eutrophic and hypereutrophic diatom species. Organic matter δ13C values decreased after 1965 A.D., seemingly contradicting other indicators of recent eutrophication in the southern basin of Lake Petén Itzá. Relatively depleted δ13C values in recent sediments, however, may reflect a contribution from 13C-depleted sewage effluent. Increased δ15N of organic matter after 1965 A.D. indicates changes in the dissolved inorganic nitrogen delivered to the lake. The relatively small increase in δ15N (∼0.6‰ ) is less than might be expected with nitrate loading from sewage and soils, and might be offset by the presence of nitrogen-fixing cyanobacteria with low δ15N values

Evaluation of Cavity Distribution Using Point-Pattern Analysis

Presence of solution cavities of different sizes poses major engineering problems in some areas of Abu Dhabi City Municipality (ADM) underlain by soluble rocks such as gypsum, calcarenite, or mudstone. This is especially critical if they are located at a relatively shallow level and are likely to cause settlement or sudden soil collapse. The Gachsaran Formation, which is composed of interlayered mudstone and gypsum, underlies all of the ADM and is known to be vulnerable to cavity formation in the area. The mudstone and gypsum beds within the upper part of the Gachsaran Formation are prone to dissolution. Numerous sinkholes have been reported, particularly in the zone between Abu Dhabi International Airport and Mafraq. Many geotechnical and geological reports and surveys were reviewed for extracting information related to geological and hydrogeological conditions causing cavities in the ADM. Information associated with cavities was cataloged and reviewed based on available data from an existing geotechnical borehole database maintained by the ADM. Cavity data obtained from borehole information was analyzed to examine cavity distributions based on the following factors: lithology, geographic clusters, cavity density, cavity size, depth to cavity, and depth to bedrock. All cavities were grouped into geographic clusters and lithological clusters for point-pattern analysis. Most cavities (87 percent) occur in mudstone or gypsum, or at an interface between these two rock types, which compose part of the Gachsaran Formation. The dissolution of carbonate and evaporites within this formation causes the formation of subsurface voids in the ADM area. Geographically, majority of cavities occurred in the Shakhbout City area, hence pattern analysis including average nearest neighbor analysis, Moran’s I for measuring spatial autocorrelation, and G-statistics for measuring high/low clustering were conducted in this area using spatial statistics tools in ArcGIS. Average nearest neighbor analysis and Moran’s- I show that cavities are strongly clustered in this area with a high confidence level (\u3e99 percent). General G-statistics identified a high clustering (hot spot) of cavities with relatively high values of depth to cavity, depth to bedrock, and number of cavities per borehole. No highly clustered large cavities were detected by the General G-statistics. Additionally, distances to the first through the 9th nearest neighbors were determined for cavities in different lithological materials and geographical clusters. Outcome of these spatial correlation and statistical analysis can be used to conduct risk assessment and the probability of occurrences of future cavities