Engelmann Spruce (Picea engelmannii) as a biological monitor of changes in soil metal loading related to past mining activity

Engelmann spruce (Picea engelmannii) is the dominant tree species in many abandoned mine areas of the Rocky Mountains. It is long-lived, and therefore, may act as a long term biological monitor of changes in soil chemistry caused by past mining activity. In this study, laser ablation inductively coupled mass spectrometry (LA-ICPMS) was used to analyze individual tree rings of Engelmann spruce for Fe, Zn, Cu, Cd, Mn, Pb and Sr concentrations. Cores were obtained from trees growing in tailings-impacted and control (non-tailings impacted) sites near the Waldorf mine (Waldorf, CO, USA). Zinc, Cu, Fe, Cd, Pb and Sr concentrations remained low and consistent over time in the control tree rings. However, in the tailings impacted cores, concentrations of Zn, Cu, Fe and Cd increase significantly in post-mining rings. In addition, Zn, Cu, Fe, and Cd concentrations in pre-mining rings of both the control and tailings impacted cores are similar, indicating that present day soil concentrations of these elements in the control area are a reasonable estimation of background for this area. Lead and Sr concentrations in control and tailings-impacted rings remained similar and relatively constant through time and are not useful in determining changes in soil chemistry due to past mining activity.     

Tree ring based Pb and Zn contamination history reconstruction in East China: a case study of Kalopanax septemlobus

To reconstruct trace metal contamination history in the Yangtze River Delta region, annual growth rings of native hardwood species, Kalopanax septemlobus, were studied as the potential archive of the past Pb and Zn pollution events. Wide distribution of K. septemlobus trees in the study area and clear annual tree rings are advantages of this potential geochemical archive. In this research, tree ring increments for 48 years, from 1960 to 2007, were analyzed for Pb and Zn concentrations. Trees were sampled in two sites, Xiaoyingpan, a contaminated area around a mine (Pb, Zn, Ag) in the Yangtze River Delta region, and a reference site 19 km away. The results show that: (1) distinct Pb and Zn concentrations increasing from 1960 to 1974 in the polluted site were coincident with increasing historical open mining activities; (2) from 1974 to 1986, Pb and Zn concentrations dramatically decreased during a conversion from above-ground exploitation to below-ground extraction; and (3) after 1992, the concentration of Zn decreased gradually, but Pb concentrations initially increased with automobile traffic from 1986 to 2004, then decreased when the number of automobiles was controlled from 2004 to 2007. In particular, Pb and Zn concentrations in tree rings had no effect on K. septemlobus growth. Pb and Zn concentrations in tree rings were linearly related with those in soils. Growth rings of K. septemlobus around the Pb, Zn, Ag mine accurately recorded historical changes in Pb and Zn deposition.     

New tree-ring dates for recent eruptions of Mount St. Helens

Distinctive patterns of growth rings in increment cores from old-growth Douglas-fir (Pseudotsuga menziesii) stands identify A.D. 1800 as a more precise date for the eruption of tephra layer T by Mount St. Helens, Washington. Layer T was previously inferred to date to about A.D. 1802. Growth patterns also establish A.D. 1480 as the date of eruption of the earlier layer Wn, previously estimated as dating to about A.D. 1500. The timing of radial tree growth places a small limitation on the seasonal resolution of these new tree-ring dates.     

高分辨率气候环境变化研究中的石笋微层

在全球变化研究领域，高分辨率重建 2000年来的气候环境变化是近期工作的主要内容之一。石笋微层由于其沉积界面完整，微层明显和组分构造有序，从而成为综合研究气候环境变化的理想载体。详细分析了石笋微层灰度和石笋微层厚度的成因、类型和影响因素，对石笋微层在高分辨率气候环境变化研究中的应用现状及目前所存在的问题作了简要介绍，并对该领域今后的发展方向提出了一些看法。     

Correlations between metals in tree-rings of Prosopis julifora as indicators of sources of heavy metal contamination

Heavy-metals (Cu, Pb and Zn) in tree-ring sequences of Prosopis juliflora, a tree species native to arid environments, were analyzed by ICP-MS. The tree-ring sequences were obtained from three specimens growing in an urban area previously reported as contaminated by the activity of a Cu smelter facility. The metal found in highest concentration in the wood was Zn, with concentrations up to 120 mg/kg and an enrichment factor up to 26; followed by Cu (up to 9.6 mg/kg, enrichment factor up to 8.6) and Pb (up to 1.4 mg/kg, enrichment factor up to 3). By assessing the correlation between different metal concentration trends, it was possible to infer two main pollution sources: vehicle traffic and Cu smelter emissions. Vehicle traffic is indicated by a correlation between Pb and Zn over time within individual trees, whereas contamination from the Cu-smelting facility is indicated by a correlation of Cu over time between trees. In tree A there was a significant within-tree correlation between Pb and Zn concentration trends (r = 0.856, P < 0.001), whereas Cu showed no correlation with the other metals. For tree B, there were no within-tree correlations between these metals, but when comparing the concentration–time trends between trees A and B, there was a significant correlation for Cu (r = 0.768, P < 0.01). The tree-ring sequence from tree C showed significant within-tree correlation for Cu:Zn (r = 0.430, P < 0.01) and for Pb:Zn (r = 0.753, P < 0.001). The highest enrichment values were found in tree A, located along the path of the growing-season dominant wind direction from the smelter facility, and not in the tree growing closer to the smelter (tree C), suggesting that the smelter’s emissions are dispersed to longer distances through the tall chimneys, attenuating the impact to the area directly closest to the smelter facility. It is concluded that Prosopis juliflora appears as a good bioindicator based on its metal accumulation capacity and lack of metal mobility among tree rings, thus providing information on the chronology and sources of heavy-metal pollution in urban and industrial areas.     

Dendroclimatic studies on conifers from central Europe and Great Britain

Schweingruber, Fritz H., BrÄker, Otto U. & SchÄr, Ernst 1979 1201: Dendroclimatic studies on conifers from central Europe and Great Britain. Boreas, Vol. 8, pp. 427–452. Oslo. ISSN 0300–9483. The use of X-ray densitometry for measuring tree rings makes it possible to consider the relations between climate and tree rings in a new light. Investigations so far have shown that it is the maximum density of the annual rings that provides the most important and best climatological information. Comparisons between density sequences are possible when the tree-ring samples come from ecologically similar sites. Site characteristics are expressed by six different tree-ring parameters. Relations between the maximum densities of various species from different regions are revealed by calculating the percentage of agreement. The growth rate of cell walls in latewood of all coniferous species from cool humid regions is limited mainly by summer temperatures. In Scotland, where the climate is cool-oceanic and relatively stable, the cell walls grow from June to October. In the subalpine zone of the Alps and the Rocky Mountains near the timber line growth takes place mainly in August and September. Maximum density in trees of temperate sites is also primarily influenced by the summer temperature. Minimum density shows the relationship to the xerothermic site characteristics. On dry sites cambial activity and cell wall growth in latewood are mainly limited by precipitation during the growth period. Samples from the subalpine zones (1500–2200 m above sea level) between latitudes 45d? and 50d? North, i.e. those from the Western Carpathians, the Alps, and the Northern Appalachian Mountains, seem to form a unity. Samples from the oceanic region (20–600 m above sea level) between 52d? and 58d?N latitudes show a different and incoherent picture. Only the present low level density during 1950–1975 is evident at all sites investigated for the last 200 years. By cross-dating the annual tree-ring sequences of living trees with samples of timber taken from ancient houses a 700-year-long chronology has been developed for the Northern Prealps in Switzerland. This chronology shows the approximate annual and decennial temperature changes; the sensitivity curve shows the different climatic variability in temperature.     

The subfossil tree deposits from the Garonne Valley and their implications on Holocene alluvial plain dynamics

Subfossil tree trunks deposits are common in large rivers, but their status as a source for dating alluvial sequences and palaeoenvironmental studies is still discussed. Particularly their origin and the process(es) of deposition as well as a possible remobilization were pointed as a limit to their use to document river alluvial changes. In this work we report the discovery of the largest subfossil trunks deposits in the Garonne valley. These new data are compared to the previous ones. A set of 17 tree trunks and more than 300 smaller wood fragments were collected. The xylologic study shows the prevalence of Quercus and a single occurrence of Ulmus. These two hardwood species are commonly associated with riparian forest. The ¹⁴C dating carried out on seven trunks and a single branch of Quercus on the outermost identified growth rings, indicates age ranging from 8400–8000 cal. BP for the oldest fragment (bough) to 4300–4000 cal. BP for the most recent tree trunk. Radiocarbon ages of the trunks are aggregated into two main periods: 5300–5600 cal. BP (four trunks) and 4300–4000 cal. BP (three trunks). The radiocarbon (charcoal) dating of the top of the alluvial sequence overlaying the trunks gives an age between 1965–1820 and 1570–1810 cal. BP, i.e. between the 2nd and the 5th c. AD. In addition, the discovery of two unpublished subfossil tree trunks deposits in Finhan are reported (six trunks). At the light of these results, we discuss previously proposed models for the Garonne floodplain building.     

Comparison of stable carbon and oxygen isotopes in Picea glauca tree rings and Sphagnum fuscum moss remains from subarctic Canada

Stable isotope ratios from tree rings and peatland mosses have become important proxies of past climate variations. We here compare recent stable carbon and oxygen isotope ratios in cellulose of tree rings from white spruce (Picea glauca), growing near the arctic tree line; and cellulose of Sphagnum fuscum stems, growing in a hummock of a subarctic peatland, in west-central Canada. Results show that carbon isotopes in S. fuscum correlate significantly with July temperatures over the past ~20 yr. The oxygen isotopes correlate with both summer temperature and precipitation. Analyses of the tree-ring isotopes revealed summer temperatures to be the main controlling factor for carbon isotope variations, whereas tree-ring oxygen isotope ratios are controlled by a combination of spring temperatures and precipitation totals. We also explore the potential of combining high-frequency (annual) climate signals derived from long tree-ring series with low-frequency (decadal to centennial) climate signals derived from the moss remains in peat deposits. This cross-archive comparison revealed no association between the oxygen isotopes, which likely results from the varying sensitivity of the archives to different seasons. For the carbon isotopes, common variance could be achieved through adjustments of the Sphagnum age model within dating error.     

新疆阿勒泰地区小冰期特征的树轮δ13C记录

建立了新疆阿勒泰地区一个长约450a的落叶松树轮碳同位素年表.该年表一个最为明显的特点是1850年后年轮δ¹³C显著降低,这是化石燃料燃烧和土地利用方式改变的缘故.在1550—1850年期间,该年表经历了明显的距平“正负”(即暖冷)变化:17世纪年轮δ¹³C值相对偏负,气温较低,18世纪年轮δ¹³C值相对偏正,温度较高.根据已有的树轮δ¹³C温度系数,17世纪的温度相对偏低约0.67～2.46℃.广泛的区域性对比表明,该年表所揭示的小冰期温度变化具有较高的可信度。     

Detection of the historical Askja ad 1875 and modern Icelandic cryptotephras in varved lake sediments – results from a first systematic search in northern Poland

Volcanic ash can disperse thousands of kilometres from the source volcano and provide valuable chronostratigraphic markers for palaeoclimate studies. We present new cryptotephra findings of historical and modern Icelandic eruptions in annually laminated lacustrine sediment records from several sites within a 570 km SW–NE transect across northern Poland. Sediments from the two lakes Wąsoskie and Szurpiły contain glass shards originating from the Plinian Askja ad 1875 eruption and showing bimodal, rhyolitic and dacitic affinities. A further cryptotephra finding in Lake Lubińskie suggests a potential origin from the Hekla ad 1845 eruption. These new findings extend the tephra dispersal map towards the south-east and provide valuable isochrons for the synchronisation of palaeoclimate proxy data at the termination of the Little Ice Age in central eastern Europe. Very low glass concentrations of modern cryptotephra in Lake Wąsoskie were potentially correlated with the Eyjafjallajökull ad 2010 eruption. Further findings in the uppermost sediments of lakes Szurpiły and Żabińskie in north-eastern Poland tentatively suggest other sources from either the Hekla and/or Kamchatkan volcanoes.     

Late Holocene forest dynamics, volcanism, and climate change at Whitewing Mountain and San Joaquin Ridge, Mono County, Sierra Nevada, CA, USA

Deadwood tree stems scattered above treeline on tephra-covered slopes of Whitewing Mtn (3051 m) and San Joaquin Ridge (3122 m) show evidence of being killed in an eruption from adjacent Glass Creek Vent, Inyo Craters. Using tree-ring methods, we dated deadwood to AD 815-1350 and infer from death dates that the eruption occurred in late summer AD 1350. Based on wood anatomy, we identified deadwood species as Pinus albicaulis, P. monticola, P. lambertiana, P. contorta, P. jeffreyi, and Tsuga mertensiana. Only P. albicaulis grows at these elevations currently; P. lambertiana is not locally native. Using contemporary distributions of the species, we modeled paleoclimate during the time of sympatry to be significantly warmer (+3.2°C annual minimum temperature) and slightly drier (−24 mm annual precipitation) than present, resembling values projected for California in the next 70-100 yr.     

Petrology and geochemistry of the 2014–2015 Holuhraun eruption,central Iceland: compositional and mineralogical characteristics,temporal variability and magma storage

The 2014–2015 Holuhraun fissure eruption provided a rare opportunity to study in detail the magmatic processes and magma plumbing system dynamics during a 6-month-long, moderate- to large-volume basaltic fissure eruption. In this contribution, we present a comprehensive dataset, including major and trace elements of whole-rock and glassy tephra samples, mineral chemistry, and radiogenic and oxygen isotope analyses from an extensive set of samples (n?=?62) that were collected systematically in several field campaigns throughout the entire eruptive period. We also present the first detailed chemical and isotopic characterization of magmatic sulfides from Iceland. In conjunction with a unique set of geophysical data, our approach provides a detailed temporal and spatial resolution of magmatic processes before and during this eruption. The 2014–2015 Holuhraun magma is compositionally indistinguishable from recent basalts erupted from the Bárðarbunga volcanic system, consistent with seismic observations for magma ascent close to the Bárðarbunga central volcano, followed by dyke propagation to the Holuhraun eruption site. Whole-rock elemental and isotopic compositions are remarkably constant throughout the eruption. Moreover, the inferred depth of the magma reservoir tapped during the eruption is consistently 8?±?5 km, in agreement with geodetic observations and melt inclusion entrapment pressures, but inconsistent with vertically extensive multi-tiered magma storage prior to eruption. The near constancy in the chemical and isotopic composition of the lava is consistent with the efficient homogenization of mantle-derived compositional variability. In contrast, occurrence of different mineral populations, including sulfide globules, which display significant compositional variability, requires a more complex earlier magmatic history. This may include sampling of heterogeneous mantle melts that mixed, crystallized and finally homogenized at mid- to lower-crustal conditions.     

Laser ablation ICP-MS analyses of tree-ring profiles in pine and birch from N Norway and NW Russia – a reliable record of the pollution history of the area?

 Laser ablation ICP-MS analysis of tree rings provides a rapid and sensitive method for investigating element concentrations and fluctuations in trees along time profiles. Time profiles obtained from pine and birch trees from a strongly polluted area in northwest Russia and a slightly polluted area at the Norwegian-Russian border show that single trees behave rather individualistically in terms of heavy metal contents as observed in the yearly growth rings. The obtained profiles can not be linked to the pollution history of the area. No correlation between pollution levels of the soils and observed metal content in tree rings can be established. Received: 6 September 1996 / Accepted: 18 November 1996     

Reconstruction of the Past Climate From Tree Rings Over Western Himalaya, India

RECONSTRUCTION OF THE PAST CLIMATE FROM TREE RINGS OVER WESTERN HIMALAYA, INDIA     

Strong correlation between summer temperature and pollen accumulation rates for Pinus sylvestris,Picea abies and Betula spp. in a high‐resolution record from northern Sweden

Highly resolved pollen spectra analysed from a 47 cm peat monolith recovered from a mire in northern Sweden exhibit climatic sensitivity in the pollen accumulation rates (PAR) of boreal treeline species. Robust temporal control, afforded through multiple AMS radiocarbon dating of the post‐atomic‐bomb‐test period (AD 1961–2002), provides a unique opportunity to compare pollen accumulation rates with the instrumental meteorological record. Strong correlations are observed between summer temperature and PAR for Pinus sylvestris, Picea abies and Betula spp. (excluding B. nana). Despite well constrained, contiguous (‘annual’) sampling, the temporal resolution of the pollen signal preserved within each sample appears to be degraded to ca. 3–5 year resolution. This is likely to reflect processes occurring during peat accumulation and pollen deposition, as well as dating uncertainties and the effects of subsampling. These findings identify limitations to the maximum resolution that may realistically be recovered from the peat archive using high‐resolution sampling protocols and AMS ¹⁴C dating. We also identify the need for additional work to quantify the role of climate on peat accumulation and the resultant impact on assemblage‐based palaeoenvironmental reconstructions within mire sequences. The strongest climate association observed for Picea abies (r = 0.53; n = 36) was extended through the monolith beyond the 42 year period of ‘annual’ sampling and the response successfully correlated with the Bottenviken historical instrumental record to AD 1860. Although only presenting data from a single site, and requiring wider replication, we conclude that for sites close to the ecological limits of tree species, where levels of anthropogenic/non‐climatic forcing on pollen production are low, well‐dated records of PAR may potentially provide a proxy for reconstructing past summer temperature variability. Copyright © 2007 John Wiley & Sons, Ltd.     

New dates and palaeoenvironmental evidence for the Middle to Upper Palaeolithic occupation of Higueral de Valleja Cave,southern Spain

A research programme has been set up at Higueral de Valleja Cave in southern Spain to investigate the late survival and eventual extinction of the southern Iberian Neanderthals and the arrival of modern humans. Of key interest in the first phase of research was to understand the depositional environment in the entrance chamber of the cave and to establish whether palaeoenvironmental and dating samples could be retrieved from the Middle and Upper Palaeolithic sequences. The outcome is a series of OSL, TL and radiocarbon dates showing that the cave was occupied by Neanderthal populations in Marine Isotope Stage (MIS) 3, if not earlier, and by modern human Solutrean populations during the last glacial maximum. Cave sediments provisionally indicate that the lower Middle Palaeolithic sequence (X–VIII) formed in warm and humid environments and the upper sequence (VIII–V) formed when the climate was cooler and drier. The presence of long grass phytoliths and of the small mammals Microtus duodecimcostatus, Microtus brecciensis and Apodemus sylvaticus in the upper sequence indicates that a range of habitat types persisted near the cave including grassland, scrubby vegetation, patchy tree cover and ponds. This raises the possibility that environmental factors were key factors in the late survival of Neanderthal populations at the cave.     

树木年轮学在环境变化研究中的应用

由于树木在其生长的过程中,需要从环境中吸收养分和能量并且从环境中汲取各种化学元素到每年的生长层(即年轮)中,所以树木年轮与它们的生长环境是密切相关的。树木年轮可以提供树轮生长的环境要素信息,其应用领域也日益扩大。文章综述了树木年轮长年表的建立以及在气候变化、环境污染等方面的若干应用,并且概述了树木年轮研究方法的进展。     

Radial distribution of lead and lead isotopes in stem wood of Norway spruce: A reliable archive of pollution trends in Central Europe

Annual growth rings of a common hardwood species, Picea abies L., were investigated as a potential archive of past atmospheric Pb pollution. Wide distribution of trees in terrestrial settings and straightforward chronology are two advantages of this potential geochemical archive, but several processes described in the literature may obscure the trends in past Pb deposition. These confounding factors include, e.g., radial post-depositional mobility of Pb in xylem, and ecosystem acidification leading to higher bioavailability of Pb. One- to five-year annual wood increments were analyzed for Pb concentrations and ²⁰⁶Pb/²⁰⁷Pb ratios at Jezeri (JEZ), Uhlirska (UHL) and Na Lizu (LIZ), three sites in the Czech Republic, differing in atmospheric Pb loads. Three to four trees per site were included in the study. Distinct Pb concentration maxima between 1960 and 1990 at the two heavily polluted sites (JEZ and UHL) coincided with historical Pb emissions known from inventories of industrial production. No Pb concentration maxima were found at one site, LIZ, situated in a national park 150 km from major pollution sources. Spruce tree rings from JEZ, located just 5 km from coal-burning power stations, contained a large proportion of coal-derived Pb (a high-²⁰⁶Pb/²⁰⁷Pb ratio of 1.19). A coal-related maximum in ²⁰⁶Pb/²⁰⁷Pb in JEZ tree rings was found using two different analytical techniques, laser-ablation multi-collector ICP MS, and single-collector sector-field ICP MS. In a three-isotope graph (²⁰⁶Pb/²⁰⁷Pb vs. ²⁰⁸Pb/²⁰⁷Pb), tree-ring data plotted into the field of ombrotrophic (i.e., rain-fed) peat bogs, suggesting negligible contribution of bedrock-derived Pb in the xylem. We concluded that none of the potential confounding factors played a major role at our sites. Annual growth rings of P. abies in Central Europe faithfully recorded historical changes in atmospheric Pb depositions.     

鄂尔多斯盆地甘泉地区下侏罗统高分辨率层序地层学分析

根据层序沉积时限以及基准面旋回界面识别标志,运用高分辨率层序地层学理论和方法,对鄂尔多斯盆地中南部甘泉地区下侏罗统进行了划分。识别出下侏罗统各级旋回层序界面,并将其划分为1个超长期、8个长期、32个中期、86个短期旋回层序。应用地层等时对比技术,以长期旋回层序为地层对比框架、中期旋回层序为地层对比单元,建立了研究区下侏罗统等时地层格架。下侏罗统沉积于盆地基底快速沉降、缓慢抬升的构造环境,在基底抬升速度周期性变化过程中,盆地边缘沉积了数层可采煤层,成为划分层序的重要依据。      

Recent chronologies for tree rings and terrestrial archives using C bomb fallout history

Tree rings representing the period from the mid-1950s up to 2001 were studied as part of an investigation of anthropogenic radionuclide input to terrestrial systems. A live specimen of Pinus sylvestris from the east coast of Ireland was felled, sampled and analysed for comparison with a similar tree felled close to the Atlantic seaboard on the west coast of Ireland. Data for the tree ring sequences were examined relative to the radionuclide content of peat profiles sampled in close proximity to the locations of the studied Pine trees.The data indicate that ¹⁴C concentrations in tree ring sequences from the east and west coasts of Ireland are virtually identical. The sequences show maximum ¹⁴C concentrations (185 and 189 pMC at east and west coast sites, respectively) that correspond closely with published data for atmospheric levels during the height of the nuclear weapons test period (1945-1980). The tree ring count for the specimen from the east coast places the ¹⁴C peak precisely at 1964, the year following the known peak in atmospheric concentrations due to above ground testing of nuclear weapons. However, ¹⁴C data show that simple ring counting of the west coast tree did not provide an accurate chronology. The data demonstrate the importance of applying dendrodating techniques using replicated site chronologies, and the value of the ¹⁴C bomb fallout curve for the construction of recent chronologies. Data show no evidence of enhanced uptake at the east coast that might suggest incorporation of output from the Sellafield nuclear complex or from the release of radioactivity resulting from an accidental fire at the plant in 1957.