A 694-year tree-ring based rainfall reconstruction from Himachal Pradesh, India   总被引：1，自引：1，他引：0  

Jayendra Singh  Ram R. Yadav  Martin Wilmking 《Climate Dynamics》2009,33(7-8):1149-1158

We developed ring-width chronologies of Cedrus deodara [(Roxb.) G. Don] and Pinus gerardiana (Wall. Ex. Lamb) from a homogeneous moisture stressed area in Kinnaur, Himachal Pradesh. Running correlation using a 50-year window with overlap of 25 years showed strong correlations between these species chronologies during the entire common period (ad 1310–2005). Response function analysis indicated that except for January–February, precipitation has a direct relationship with growth of these species. We therefore combined both the species chronologies to develop a statistically calibrated reconstruction of March–July precipitation that spans from ad 1310–2004, and explains 46% of the variance contained in the instrumental data from the calibration period 1951–1994. In the past 694 years of the reconstruction, the wettest period was in the twentieth century (1963–1992) and the driest in the eighteenth century (1773–1802). The relationships observed between reconstructed precipitation and Indian summer monsoon on interdecadal scale, SOI, PDO and NAO indicate the potential utility of such long-term reconstructions in understanding the large-scale climate variability. Multi-taper method (MTM) spectral analysis indicated significant (p < 0.05) spectral peaks at 2–4, 6, 8, 10, 30, 33, 37 and 40–42 years in the reconstructed precipitation data.  相似文献   

Evaluation of uncertainties in the CRCM-simulated North American climate   总被引：2，自引：2，他引：0  

Ramón de Elía  Daniel Caya  Hélène Côté  Anne Frigon  Sébastien Biner  Michel Giguère  Dominique Paquin  Richard Harvey  David Plummer 《Climate Dynamics》2008,30(2-3):113-132

This work is a first step in the analysis of uncertainty sources in the RCM-simulated climate over North America. Three main sets of sensitivity studies were carried out: the first estimates the magnitude of internal variability, which is needed to evaluate the significance of changes in the simulated climate induced by any model modification. The second is devoted to the role of CRCM configuration as a source of uncertainty, in particular the sensitivity to nesting technique, domain size, and driving reanalysis. The third study aims to assess the relative importance of the previously estimated sensitivities by performing two additional sensitivity experiments: one, in which the reanalysis driving data is replaced by data generated by the second generation Coupled Global Climate Model (CGCM2), and another, in which a different CRCM version is used. Results show that the internal variability, triggered by differences in initial conditions, is much smaller than the sensitivity to any other source. Results also show that levels of uncertainty originating from liberty of choices in the definition of configuration parameters are comparable among themselves and are smaller than those due to the choice of CGCM or CRCM version used. These results suggest that uncertainty originated by the CRCM configuration latitude (freedom of choice among domain sizes, nesting techniques and reanalysis dataset), although important, does not seem to be a major obstacle to climate downscaling. Finally, with the aim of evaluating the combined effect of the different uncertainties, the ensemble spread is estimated for a subset of the analysed simulations. Results show that downscaled surface temperature is in general more uncertain in the northern regions, while precipitation is more uncertain in the central and eastern US.  相似文献   

Modeling the bi-national city process of Eilat–Aqaba,a bi-national city in a cold peace setting     

José Ramón Xilotl Soberon  Yodan Rofé 《GeoJournal》2017,82(6):1263-1274

Officially at peace since 1994, Israel and Jordan have since established multiple cooperation schemes with the aim of transitioning from a described cold peace to a self-sustaining warm peace. One cooperation scheme that is particularly interesting from the point of view of Border and Urban Studies is the case of Eilat, Israel and Aqaba, Jordan. These tourist cities, located in the Arava Valley, are both physically isolated and strategically placed on the Red Sea coast. Since 2001 they have been considered as a potential bi-national city, and so far remain as the only one studied in a cold peace setting. Yet doubt persists as to whether a bi-national city can actually exist under such conditions. The purpose of this article is to firmly establish the place of Eilat–Aqaba as a bi-national city through the use of a unique analysis of the region that updates and elaborates findings dating from 2001. This concludes in modeling the Bi-national City Process of Eilat–Aqaba.  相似文献   

A transition from CMIP3 to CMIP5 for climate information providers: the case of surface temperature over eastern North America     

Marko Markovic  Ramón de Elía  Anne Frigon  H. Damon Matthews 《Climatic change》2013,120(1-2):197-210

The release of new data constituting the Coupled Model Intercomparison Project—Phase 5 (CMIP5) database is an important event in both climate science and climate services issues. Although users’ eagerness for a fast transition from CMIP3 to CMIP5 is expected, this change implies some challenges for climate information providers. The main reason is that the two sets of experiments were performed in different ways regarding radiative forcing and hence continuity between both datasets is partially lost. The objective of this research is to evaluate a metric that is independent of the amount and the evolution of radiative forcing, hence facilitating comparison between the two sets for surface temperature over eastern North America. The link between CMIP3 and CMIP5 data sets is explored spatially and locally (using the ratio of local to global temperatures) through the use of regional warming patterns, a relationship between the grid-box and the global mean temperature change for a certain time frame. Here, we show that local to global ratios are effective tools in making climate change information between the two sets comparable. As a response to the global mean temperature change, both CMIP experiments show very similar warming patterns, trends, and climate change uncertainty for both winter and summer. Sensitivity of the models to radiative forcing is not assessed. Real inter-model differences remain the largest source of uncertainty when calculating warming patterns as well as spatially-based patterns for the pattern scaling approach. This relationship between the datasets, which may escape users when they are provided with a single radiative forcing pathway, needs to be stressed by climate information providers.  相似文献   

Stakeholder perspectives on use, trade, and conservation of medicinal plants in the Rasuwa district of central Nepal     

Yadav UPRETY  Ram C.POUDEL  Hugo ASSELIN  Emmanuel K.BOON  Krishna K.SHRESTHA 《山地科学学报》2011,8(1):75-86

People’s livelihood in several Himalayan regions largely depends on collection, use, and trade of medicinal plants. Traditional use is generally not a problem, but commercial gathering of selected species to meet increasing national and international demand can result in over-exploitation. Sustainable management of medicinal plants requires a clear understanding of the respective roles, responsibilities and viewpoints of the various stakeholders involved. Through personal interviews and group discussions, this study aimed at investigating the views of two stakeholder groups on use, trade and conservation of medicinal plants in the Rasuwa district of Nepal. Local people and district and national organizations agreed that medicinal plants are collected for a combination of commercial and personal uses. Perceptions on market availability differed significantly: 100 % of the respondents from district and national organizations saw markets as easily available, against only 36 % for local people. This could explain why medicinal plants were perceived by local people to contribute less to income generation than to livelihood improvement. Different viewpoints were also expressed concerning the status of medicinal plants in the district: 81 % of the respondents from district and national organizations considered that medicinal plants were threatened, compared to only 28 % for local people. Despite this disparity, both stakeholder groups agreed upon potential threats to medicinal plants: over-harvesting; habitat loss due to land-use change and deforestation; and over-grazing by livestock. Several challenges were identified regarding sustainable management of medicinal plants, such as ambiguous policies; lack of resources, information and infrastructures; habitat degradation; and over-exploitation. Despite these challenges, respondents agreed that the medicinal plants sector offers huge opportunities in the Rasuwa district, given resource availability, community awareness and motivation, and the priority given to the sector by governments and other agencies. Proper collaboration, communication and coordination among stakeholders are needed to grab these opportunities.  相似文献   

Distribution of butyltins in the waters and sediments along the coast of India     

Garg A  Meena RM  Jadhav S  Bhosle NB 《Marine pollution bulletin》2011,62(2):423-642

Water and surface sediment samples were analyzed for butyltins (TBT, DBT, MBT) from various ports along the east and west coast of India. The total butyltin (TB) in water samples varied between ∼1.7 and 342 ng Sn l⁻¹, whereas for sediments it varied between below detection limit to 14861 ng Sn g⁻¹ dry weight of sediment. On an average Chennai port recorded the highest level of butyltins in the sediments while Paradip recorded the highest level of butylins in the waters. A fairly good relationship between the TB in the sediment and overlying water samples, as well as between organic carbon and TB, implicates the importance of adsorption/desorption process in controlling the levels of TBT in these port areas. In India the data on organotin pollution is very sparse; most of the port areas have been surveyed for butyltins for the first time during this study.  相似文献   

A comparative evaluation of minerals and trace elements in the ashes from lignite, coal refuse, and biomass fired power plants     

Smriti SinghLal C. Ram  Reginald E. MastoSantosh K. Verma 《International Journal of Coal Geology》2011,87(2):112-120

Coal being a limited source of energy, extraction of energy from other sources like lignite, coal-refuse, and biomass is being attempted worldwide. The minerals and inorganic elements present in fuel feeds pose different technological and environmental concerns. Lignite ash, refuse ash, and biomass ash collected from Indian power plants burning lignite, coal-refuse, and mustard stalk, respectively, were analyzed for physico-chemical characteristics and trace elements. The lignite ash has high SiO₂, CaO, MgO, Al₂O_3, and SO₃; the refuse ash has high SiO₂ and Fe₂O₃, but low SO₃; the biomass ash has high SiO₂ (but low Al₂O₃), and high CaO, MgO, K₂O, Na₂O, SO₃, and P₂O₅. A substantial presence of chloride (2.1%) was observed in the biomass ash. Quartz is the most abundant mineral species. Other minerals are mullite, hematite, gehlenite, anhydrite, and calcite in the lignite ash; orthoclase in the refuse ash; albite, sanidine, gehlenite, anhydrite, and calcite in the biomass ash. Ashes with high concentrations (> 100 mg/kg) of trace elements are: lignite ash (V < La < Mn < Cr < Ni < Nd < Ba < Ce, Zn < Sr); refuse ash (Cr < Ce < V < Rb < Mn < Sr, Zn < Ba); biomass ash (Cu < Zn < Ba, Sr). Based on Earth crust normalization, Co, Ni, As, Se, Mo, Zn, Pb, U, and REEs (except Pr and Er) are enriched in the lignite ash; molybdenum, Zn, Cs, Pb, Th, U, La, Ce, and Lu in the refuse ash; and Mo, Zn, Sr, Cs, Pb, and Lu in the biomass ash. Elements As, Zn, Mo, Ni, Pb, Rb, Cr, V, Ba, Sr, and REEs are correlated with Al, indicating the possibilities of their association with aluminum silicates minerals. Similarly, barium, Cs, Th, and U are correlated with iron oxides; molybdenum and Sr may also be associated with sulfates and chlorides. Due to the alkaline nature of these ashes, the high concentrations of As and Se in the lignite ash; molybdenum in the biomass ash; and Se in the refuse ash may pose environmental concerns.  相似文献   

Criteria for recognition of localization and timing of multiple events of hydrothermal alteration in sandstones illustrated by petrographic,fluid inclusion,and isotopic analysis of the Tera Group,Northern Spain     

Laura González-Acebrón  R. H. Goldstein  Ramón Mas  José Arribas 《International Journal of Earth Sciences》2011,100(8):1811-1826

Stratigraphic relations, detailed petrography, microthermometry of fluid inclusions, and fine-scale isotopic analysis of diagenetic phases indicate a complex thermal history in Tithonian fluvial sandstones and lacustrine limestones of the Tera Group (North Spain). Two different thermal events have been recognized and characterized, which are likely associated with hydrothermal events that affected the Cameros Basin during the mid-Cretaceous and the Eocene. Multiple stages of quartz cementation were identified using scanning electron microscope cathodoluminescence on sandstones and fracture fills. Primary fluid inclusions reveal homogenization temperatures (Th) from 195 to 350°C in the quartz cements of extensional fracture fillings. The high variability of Th data in each particular fluid inclusion assemblage is related to natural reequilibration of the fluid inclusions, probably due to Cretaceous hydrothermal metamorphism. Some secondary fluid inclusion assemblages show very consistent data (Th = 281–305°C) and are considered not to have reequilibrated. They are likely related to an Eocene hydrothermal event or to a retrograde stage of the Cretaceous hydrothermalism. This approach shows how multiple thermal events can be discriminated. A very steep thermal gradient of 97–214°C/km can be deduced from δ¹⁸O values of ferroan calcites (δ¹⁸O −14.2/−11.8‰ V-PDB) that postdate quartz cements in fracture fillings. Furthermore, illite crystallinity data (anchizone–epizone boundary) are out of equilibrium with high fluid inclusion Th. These observations are consistent with heat-flux related to short-lived events of hydrothermal alteration focused by permeability contrasts, rather than to regional heat-flux associated with dynamo-thermal metamorphism. These results illustrate how thermal data from fracture systems can yield thermal histories markedly different from host-rock values, a finding indicative of hydrothermal fluid flow.  相似文献   

Heavy metals accumulation and ecophysiological effect on <Emphasis Type="Italic">Typha angustifolia</Emphasis> L. and <Emphasis Type="Italic">Cyperus esculentus</Emphasis> L. growing in distillery and tannery effluent polluted natural wetland site,Unnao, India     

Sangeeta Yadav  Ram Chandra 《Environmental Earth Sciences》2011,62(6):1235-1243

Distillery and tanneries are major source of heavy metals pollution in natural wetland sites in India. Present study deals with the heavy metals accumulation potential of Typha angustifolia and Cyperus esculentus growing in distillery and tannery effluent polluted wetland sites. The metal accumulation pattern in both macrophytes showed direct correlation with the metal content in sediments. Both macrophytes were observed root accumulator for Fe, Cr, Pb, Cu, and Cd. The metal accumulation in T. angustifolia was found higher than C. esculentus, and accumulation pattern was Fe > Mn > Cr > Zn > Pb > Cu > Ni > Cd. Simultaneously, chlorophyll, protein, cysteine, and ascorbic acid were also induced in T. angustifolia than C. esculentus. In addition, formation of multinucleolus in shoot of T. angustifolia was found an evidence of extra protein synthesis for tolerance under stress conditions. Hence, C. esculentus was observed potential but less tolerance for metals than T. angustifolia. Therefore, these wetland plants could be used for phytoremediation of heavy metals from wastewater.  相似文献   

Radiocarbon age inversions and progression: source and causes in Late Holocene sediments from Lake Chapala,western Mexico   总被引：1，自引：0，他引：1  

Pedro F. Zárate-del-Valle  Hermes U. Ramírez-Sánchez  François Fernex  Bernd R. T. Simoneit  Isabel Israde-Alcántara 《Environmental Earth Sciences》2011,63(5):1011-1019

The results of eight radiocarbon datings of Lake Chapala sediments (site T46) are presented, the age inversions (AI) observed and their age progression discussed. As deduced from some AIs and the ²¹⁰Pb activity (site CHP4), the bioturbation zone in the lake varies over a depth of 5–25 cm. The linear sedimentation rates (LSRs) calculated from ¹⁴C ages do not match the LSR calculated from unsupported ²¹⁰Pb activity for the upper sediments. This demonstrates the usefulness of dating sediments with complementary radiometric techniques such as short-lived isotope counting (SLIC), i.e., ²¹⁰Pb and ¹³⁷Cs. This approach leads to the following conclusions: (1) The incorporation of detrital particles with ancient carbon into the sedimentary column of the lake occurred by a combination of: (a) the presence of outcrops of hydrothermal petroleum with ages >40 ka (ka = thousands of years) in the lake, and (b) mass transport due to the presence of two elongated gyre circulation patterns integrated by cyclonic circulation (counterclockwise) in the north portion of the lake and anticyclonic circulation in the southern part. (2) Consequently, the ¹⁴C ages of shallow lake sediments have geologic ages one order of magnitude greater compared to their ages determined by the ²¹⁰Pb method. (3) A bioturbation mechanism is not necessary to explain the ¹⁴C AI in the top 70 cm and from 110 to 150 cm depth of the sediments. (4) According to the biological proxies data for the last 600 years B.P., the paleoclimate at Lake Chapala has changed from sub-humid to dry environmental conditions, and eutrophication has increased over the past 100 years due to local input from ongoing agricultural activities.  相似文献