越南下龙湾石炭纪巴什基尔期Pseudostaffella(筵)类动物群

作者报道了越南下龙湾地区的一个(筵)类动物群,该动物群产于下龙湾吉婆岛东的一个小岛的石灰岩地层中,其中以Pseudostaffella为主,Eostaffella次之.文中描述7个种,即:Pseudostaffella composita,P.subquadrata vozhgalica,P.antiqua,P.antiqua grandis,Eostaffella postmosquensis,E.mosquensis及E.galinae,其中以Pseudostaffella composita最为丰富,可称之为Pseudostaffella动物群.该动物群层位高于下龙湾地区Bacson组中的Millerella-Eostaffella带,相当于宾夕法尼亚系巴什基尔阶上部,中国贵州盘县滑石板阶层型剖面的Pseudostaffella composita-P.paracompressa带,俄罗斯下巴什基尔阶Prikamsky层的Pseudostaffella prae-gorskyi-Profusulinella staffellaeformis带的一部分,以及北美宾夕法尼亚系莫洛阶Millerella带与阿托克阶Profusulinella组合带之间的Pseudostaffella和Eostaffella的化石层.下龙湾Pseudostaffella(筵)类动物群的发现具有重要的地层学和古生物学意义,它对于进一步认识该地区地质演化及古生物地理变迁均有裨益.     

The Lower Devonian conodont Pedavis pesavis and the pesavis Zone

Valenzuela-Ríos, 7.1. 1994 10 15 The Lower Devonian conodont Pedavis pesavis and the pesavis Zone.
Records from Europe and Western North America suggest that a diversification of Pedavis faunas took place around the base of what has been called the pesavis Zone. This level is reviewed in comparison to sequences in Western North America and Spain. Hitherto, two different taxa, Pedavis pesavis S.S. and Pedavis striatus (= Icriodus pesavis of Klapper 1969) have been used indiscriminately in defining the base of the pesavis Zone. This revision points out that the chronostratigraphic problems derived from an unknown phylogenetic history of both P. striatus and P. pesavis remain still unsolved, and thii fact challenges the continued use of either taxon as a zonal index for dating and correlating purposes. To improve this situation a new biostratigraphic unit above the delta Zone is proposed, the pandora beta - gilberti unit. This unit is unambiguosly defined, and thus it now enables accurate correlation on a global-scale basis above the delta Zone. Conodonts, biostratigraphy, Lower Devonian, Pyrenees, Nevada .     

The Furongian (upper Cambrian) Alum Shale of Scandinavia: revision of zonation

The zonation of the Furongian Alum Shale in Scandinavia, based on olenid trilobites, is reviewed and revised. The current scheme is rooted in a detailed zonation introduced in the late 1950s with subzones that subsequently have been elevated to zonal rank. Ten of these zones are difficult to recognize in all Alum Shale districts, and a revised zonation is proposed, focused on unambiguous identification throughout Scandinavia. The difficulties in recognizing zones in some districts mostly relate to biofacies differentiation. Representatives of Ctenopyge are, for instance, common in palaeo-offshore areas, whereas pelturines are rare in these settings and vice versa in palaeo-inboard settings. The following modifications of the olenid zonation are proposed: the Olenus scanicus Zone is renamed the O. scanicus–O. rotundatus Zone; the Ctenopyge similis and Ctenopyge spectabilis zones are replaced by the Sphaerophthalmus modestus–Sphaerophthalmus angustus Zone; the Ctenopyge tumida Zone is renamed the Peltura acutidens–Ctenopyge tumida Zone; the Peltura scarabaeoides Subzone is restored (as a zone) and replaces the Ctenopyge bisulcata and Ctenopyge linnarssoni zones. The Parabolina heres megalops (Sub)Zone is reinstated and replaces the Peltura paradoxa Zone; the Acerocarina granulata and P. costata zones are combined as the Acerocarina granulata–Peltura costata Zone. In addition, the name Proceratopyge nathorsti–Simulolenus alpha Zone is suggested for the polymerid zone corresponding to the upper Miaolingian Agnostus pisiformis Zone. The proposed changes reduce the number of Furongian Zones to 23, allocated to six superzones. No subzones are recognized, but some zones can potentially be subdivided for improved local correlation. The stratigraphical ranges of all Furongian olenid trilobites and agnostoids described from Scandinavia are summarized.     

New insights into the base of the Emsian (Lower Devonian) in South China

Traditionally, the lower boundary of the Emsian (Lower Devonian) has been defined as the base of the dehiscens Zone marked by the first entry of the conodont Polygnathus dehiscens. However, following taxonomic revision of P. dehiscens, the current practice is to use the first appearance of P. kitabicus to define the base of the Emsian. As a result, specimens previously identified as P. dehiscens from South China need to be thoroughly reviewed. Careful examination of the oral and aboral features of the platform reveal that most specimens previously described as P. dehiscens from nine sections in Guangxi and Yunnan actually refer to P. excavatus excavatus or P. excavatus ssp. 114. In the South China Block, widespread and massive deposition of Devonian carbonates began during the time of the excavatus Zone, whereas the kitabicus Zone is probably located in the underlying strata, which mainly comprise marine siliciclastic rocks. Thus, the precise level of the lower boundary of the Emsian in South China is still unknown.     

Pollen stratigraphy of holocene sediments from the grand rapids area,Manitoba, Canada

Two sections of sediments from a shallow lake on The Pas moraine gave a ¹⁴C age of 7 220 ± 110 years, a likely minimum age for the recession of Glacial Lake Agassiz II. Three pollen zones are recognized as follows: Zone 1, from 7 300 to about 6 200 B.P., dominated by NAP(40–75%) with 6–22% spruce, 1–10% juniper and minor proportions of other trees, interpreted as a treeless vegetation, except for scattered spruce, dominated by juniper, grasses, sagebush and herbs. Zone 2, from 6 200 to 3 500 B.P., dominated by pine, with a mixed forest of poplar, pine and spruce. Zone 3, an assemblage occurring from 3 500 B.P. to the present, consisting of spruce, pine and birch, representing the modern mixed boreal forest. These findings agree with archaeological data suggesting a shift from a plains to a woodland culture.     

Didymograptus bifidus and the trans-Atlantic correlation of the Lower Ordovician

Bergström, S. M. & Cooper, R. A.: Didymograptus bi'us and the trans-Atlantic correlation of the Lower Ordovician.
The co-occurrence of Didymograptus bifidus (Hall) and Prioniodus mae Lindstrom, and other conodonts of the middle Arenigian P. mae Zone in the upper part of the Marathon Limestone, Texas, provides the first non-graptolitic evidence that at least part of the D. bifidus Zone, as recognized in the reference area for the standard graptolite zonal succession of the Ordovician of North America, is as old as the BritisK D. nitidus Zone. This has important implications for the correlation of Early Ordovician rocks within North America and across the Atlantic. A regional review of the available evidence from conodonts and shelly megafossils indicates that the D. bifidus—D. artus graptolite assemblage widely used for identification of the D. bifidus Zone in North America ranges in age from the middle Arenigian to, probably, the lower Llanvirnian, and hence is of relatively limited use for precise local and regional correlations. It is also noted that the base of the North American Middle Ordovician falls within hograptus 'caduceus' Zone strata that apparently correspond to an interval in the middle to upper part of the British D. hirundo Zone.     

On the Holocene vegetation history of the Argive Plain (Peloponnese,southern Greece)

Palynological investigations have been carried out on a sediment core from ancient Lake Lerna, a former fresh water lagoon in the western part of the Argive plain, Peloponnese, southern Greece. The sequence starts at 6800 B.P. (5700 cal B.C.). The lowest part of the pollen diagram shows a period of open deciduous oak woods, which may have been influenced by human impact already (Zone I). It is followed by a period of dense deciduous oak woods (Zone II), which lasted until the beginning of the Bronze Age ca. 4800 B.P. (3500 cal B.C.). Later, the diagram indicates strong human influence such as woodland clearance, the spread of maquis, phrygana and pine in Zones IIIa-IV. During the Archaic, Geometric and Classical periods after ca. 2700 B.P. (800 cal B.C.) there is evidence of a phase of extensive olive farming (Zone IIIb). In the same zone, after a period of scattered finds, there is an almost continuous Juglans curve. Zone IV is characterised by high pine values. In Zones I-II the evidence of evergreen Mediterranean plants is surprisingly small. In times with no discernible human influence (Zone II), deciduous oaks dominate, with no evidence for a climax vegetation of the Oleo-Ceratonion alliance. Olea europaea is the only species of that alliance traceable by its pollen in the diagram, while Ceratonia pollen is totally absent.     

An updated Telychian (Late Llandovery, Silurian) conodont zonation based on Baltic faunas

Five conodont zones, Pterospathodus eopennatus ssp. n. 1, P. eopennatus ssp. n. 2, P. amorphognathoides angulatus , P. a. lennarti and P. a. lithuanicus , are described in the interval previously known as the P. celloni Zone. The new zones are grouped into two superzones: the first two form the P. eopennatus Superzone and the other three the P. celloni Superzone. All zones correspond to the intervals of the total ranges of the nominal taxa and to the boundaries between the zones to the levels at which one taxon was evolutionally replaced by another. The lower boundary of the P. a. amorphognathoides Zone is redefined. The P. eopennatus ssp. n. 2, P. a. angulatus and P. a. amorphognathoides zones are further subdivided into the Lower and Upper subzones. Although the zones described are mainly based on data from Estonia, they can be recognized all over the world, in most sections containing Telychian strata and from where adequate data are available. Most of the subzones can so far be applied only in a limited area.     

内蒙古乌海大石门奥陶系牙形刺和Histiodella动物群发现的意义

本文描述了内蒙古乌海大石门剖面奥陶系的牙形刺动物群:下克里摩里组主要有Histiodella kristinae,H.holodentata,H.wuhaiensis sp.nov.,Polonodus newfoundlandensis和Paroistodus horridus等,应归属于中奥陶统达瑞威尔阶(Darriwilian)之Histiodella kristinae带,并在同一剖面上与笔石Pterograptus elegans带和Didymograptus murchisoni带下部相当;下克里摩里组顶部产Histiodella kristinae,Baltoplacognathus cf.reclinatus,Periodon aculeatus和Protopanderodus rectus等,所以大石门剖面的Histiodella kristinae带顶部可能已与北欧Pygodus serra带之底部相当;乌拉力克组底部的砾状灰岩透镜体产有牙形刺Pygodus anserinus?,Protopanderodus liripipus,Yangtzeplacognathus protoramosus和Dapsilodus viruensis等,其中Pygodus anserinus?Pa分子(器官种的一组成分子)的口面瘤齿列的瘤齿比较粗糙,与典型的Pygodus anserinus稍有不同,且在牙形刺十分丰富的样品中仅有一枚此种之Pa分子,所以本文尚有疑问地把这层砾状灰岩归入Pygodus anserinus带,同时不能排除把它归入Pygodus serra带顶部Yangtzeplacognathus protoramosus亚带的可能。由于此剖面牙形刺化石与丰富的笔石共生,为牙形刺带与笔石带的精确对比提供了直接证据。Histiodella动物群在此剖面的发现,不仅具有十分重要的地层意义,而且具有明显的岩相古地理意义。本文详细描述了新种Histiodella wuhaiensis并讨论了Histiodella属5个种之区别。     

On Analysis of Quant itative Geology for Quaternary Sporopollen in the Northern China Plain

The paper recommends the application of the hierarchical cluster, order cluster analysis and order correspondence analysis in dividing quaternary sporo-pollen zones, and the use of continuity coefficient (K) in defining classification number of the order cluster, the use of the ratio of factor load (D) in extending the result of the correspondence analysis to the classification of order samples. The application of above mentioned coefficients can help to assess better rationality in dividing sporopollen zones and provide evidence for the determination of the quaternary lower boundary, the evolution features of the paleovegetation and the paleoclimate. The sporo-pollen data of 36.2 samples in seven boreholes from the Northern China Plain (between 113–118˚E and 35–40˚N) were computed in this paper, and as a result, five sporopollen zones and six sporo-pollen subzones were defined. These zones and subzones, establishedon the basis of quantitative analysis, are closely related to the paleomagnetic polar and showno difference from the strata division by geological comprehensive interpretation, the ratio ofmisinterpretation is generally less than 5%. The age for each sporo-polten zones is as follows: sporo-pollen zone 1 ought to be Holocene Epoch, which is less than 1–1.2× 10⁴ years B. P. (Determined by the 14C method); ZoneⅡ ought to be Late Pleistocene, its boundary is located near Blake event in the paleomagneticpolar column; Zone Ill, Middle Pleistocene, B/M, about 73× 10⁴ years B. P.; Zone IV, EarlyPleistocene, M/G, about 248×10⁴ years B. P.; and Zone V, Pliocene, which is located under Gauss epoch in the paleomagnetic Polar column.     

Late Middle to Late Frasnian Atrypida, Pentamerida, and Terebratulida (Brachiopoda) from the Namur-Dinant Basin (Belgium)

In the Namur-Dinant Basin (Belgium), the last Atrypida and Pentamerida originate from the top of the Upper Palmatolepis rhenana Zone (Late Frasnian). Within this biozone, their representatives belong to the genera Costatrypa, Desquamatia (Desquamatia), Radiatrypa, Spinatrypa (Spinatrypa), Spinatrypina (Spinatrypina?), Spinatrypina (Exatrypa), Waiotrypa, Iowatrypa and Metabolipa. No representative of these orders occurs within the Palmatolepis linguiformis Zone. The disappearance of the last pentamerids, mostly confined to reefal ecosystems, is clearly related to the end of the edification of the carbonate mounds; it precedes shortly the atrypid one. This event, resulting from a transgressive episode, which induces a progressive and dramatic deterioration of the oxygenation conditions, takes place firstly in the most distal zones of the Namur-Dinant Basin (southern border of the Dinant Synclinorium; Lower P. rhenana Zone). It is only recorded within the Upper P. rhenana Zone in the Philippeville Anticlinorium, the Vesdre area, and the northern flank of the Dinant Synclinorium. It would seem that the terebratulids were absent during the Famennian in this basin, probably due to inappropriate facies. Among the 13 species described or briefly discussed (Palmatolepis hassi to Upper P. rhenana zones), Pseudoatrypa godefroidi nov. sp. and Spinatrypina (Exatrypa) marmoris nov. sp. are proposed as new.     

Potential causes of enhanced transfer of mercury to St. Lawrence River Biota: implications for sediment management strategies at Cornwall, Ontario, Canada

We examined factors and pathways involved in the transfer of mercury (Hg) to the food web in St. Lawrence River embayments near Cornwall, Ontario, where natural remediation of contaminated sediments (eventual burial by settling of cleaner sediments) has been adopted as a management strategy. Yellow perch (Perca flavescens) from one of the study zones (Zone 1) along the river by Cornwall contained significantly higher total mercury (THg) concentrations than perch from other equally contaminated zones. While THg concentrations in benthic invertebrates did not vary among contaminated zones, THg concentrations in yellow perch and invertebrate prey recovered from the perch stomachs were 1.5–2.5 times higher in Zone 1 than those from other zones, suggesting that prey selection affects THg accumulation more than habitat location. No significant differences were found in THg concentrations among different prey species within Zone 1, although there were significant differences in THg concentrations in the same prey species within Zone 1. In contrast, THg concentrations among different prey species increased significantly with trophic level in other contaminated and reference zones. The lack of correspondence between trophic position and THg accumulation in Zone 1 suggests two possibilities: (1) yellow perch in Zone 1 are highly mobile and are assimilating THg from a wide range of prey across Zone 1 with variable THg concentrations and (2) there may be an important non-dietary source of THg to the Zone 1 food web. Potential waterborne Hg sources to Zone 1 were investigated. Whereas THg and MeHg values in discharges from a disused canal were similar to Zone 1 surface water values (0.97 and 0.04 ng l^?1, respectively), concentrations in storm sewer and combined sewer overflows discharging in the vicinity of Zone 1 were 19–45-fold (THg) and 2–4-fold (MeHg) higher than upstream river water. Contributions of Hg to the water column from sediment–water diffusion, estimated using a simple, well-mixed reactor model, ranged 0.05–0.1% of the surface water THg concentration and 1–2% of the MeHg concentration measured in summer months in Zone 1. Although not investigated in the other zones, a strong correlation (r ² = 0.82) was found between MeHg in porewater and amphipod concentrations in Zone 1, indicating that the sediment porewater is bioavailable and likely an important pathway for transfer of sediment Hg to the foodweb. Large areas of Zone 1 contain bark deposits and produce high rates of gas ebullition, and may not provide favourable conditions for progressive burial with clean sediments and attenuation of Hg transfer to biota through natural remediation. Careful monitoring of surface sediment concentrations and biota is required in these areas. Failure to reduce concentrations of Hg in these media would indicate alternative or additional management measures are required.     

Foraminiferal biostratigraphy and sequence stratigraphy across the mid-Carboniferous boundary in the Central Taurides,Turkey

The Aladağ Unit is one of the main tectonic units in the Tauride Belt, located in southern Turkey. It includes a continuous Paleozoic carbonate sequence encompassing the mid-Carboniferous boundary, with outcrops being especially well exposed in the Hadim region. The boundary succession lithology is mainly composed of carbonates with intercalated quartz arenitic sandstone layers. Based on foraminifers, four biostratigraphic zones have been defined in the interval from the Upper Serpukhovian to the Lower Bashkirian. These zones are, in ascending order: the Eostaffella ex gr. ikensis—E. postmosquensis Zone (Zapaltyubinsky Horizon, Upper Serpukhovian); the Plectostaffella jakhensis—P. bogdanovkensis Zone, and the Millerella marblensis Zone (Bogdanovsky Horizon, lower Bashkirian); and the Semistaffella sp. Zone (Syuransky Horizon, lower Bashkirian). The mid-Carboniferous boundary occurs between the Eostaffella ex gr. ikensis—E. postmosquensis Zone and the Plectostaffella jakhensis—P. bogdanovkensis Zone. Boundary beds are characterized by eight, repeatedly occurring microfacies types, namely: (1) coated crinoidal packstone; (2) coated bioclastic grainstone; (3) oolitic grainstone; (4) oolitic packstone-grainstone; (5) intraclastic grainstone; (6) mudstone-wackestone; (7) quartz-peloidal packstone; and 8) quartz arenitic sandstone. Based on microfacies stacking patterns, various types of shallowing-upward cycles have been recognized. Depositional sequences and sequence boundaries are correlatable with those described from North America and Russia and Carboniferous global sea-level curves. The duration of cycles has been estimated as 100 ky, suggesting that cycle periodicities correspond to the Milankovitch eccentricity band.     

Plankton stratigraphy of the Early and Middle Miocene Kareem and Rudeis Formations in the central part of the Gulf of Suez,Egypt

The planktonic foraminifera and nannofossils of three wells in the Gulf of Suez penetrating the Early to Middle Miocene Upper Rudeis and Kareem Formations are attributed (from top to base) to the Middle Miocene Globorotalia peripheroronda Partial Range Zone (M6), the earliest Middle Miocene Praeorbulina sicana–Orbulina suturalis Interval Zone (M5), subdivided into the Praeorbulina glomerosa s. strict.–O. suturalis Interval Subzone (M5b) and the P. sicana–P. glomerosa s. str. Interval Subzone (M5a) and the Early Miocene Globigerinoides bisphericus Partial Range Subzone (M4b). The appearance of O. suturalis at the base of Subzone M5b represents the final stage of evolution of the Globigerinoides trilobus–Praeorbulina–Orbulina Lineage. In addition, the calcareous nannoplankton assemblages indicate the Sphenolithus heteromorphus Zone (NN5) and the Helicosphaera ampliaperta Zone (NN4). These biozones are well correlatable with those established by El-Heiny and Martini (1981, Geol Mediterr. Tome, VIII(2): 101–108) from the southwestern flank of the Gulf of Suez.     

Pollen AnalysiS and Paleoenvironment Study of Late Pleistocene in Daganba,Guizhou Province

In this paper, the division of the two pollen zones is discussed based on the results of pollen and spores analysis and 14C dating in the Daganba area, Zhijin County, central Guizhou Province. Zone Ⅰ represents a forest of mixed evergreen-deciduous broad-leaved trees closed subtropic mountain and dominated by Fagus, Quercus, Cyclobalanopsis, Carpinus and Castanea (Castanopsis, Lithocarpus) together with Pinus, Tsuga and Abies till 23000 yr B.P. It stands for the Dali interstadial climate, cool and moist. Zone Ⅱ vegetation adopted dry climate. During the time from 23000 yr B. P. to the fullglacial period the forest cowered and the fern extended. The pioneer trees such as Pinus, Betula began to grow towards the end of the dry phase. The genus Fagus is of great importance in studing ecology and geography of the flora. The retirement and growth of Fagus forest reveals the paleoenvironment changes.     

Evolution of C isotopes in the Cambrian of China: implications for Cambrian subdivision and trilobite mass extinctions

Carbon and oxygen isotopes were studied in fossiliferous Cambrian carbonates in northwestern Hunan Province (South China) and in northern Anhui and southern Shandong provinces (North China). Two major C isotope excursions related to biological events occur in the Wangcun section (Yongshun County, northwestern Hunan), which consists of a slope carbonate sequence (510 m thick) containing abundant trilobites. The first C isotope excursion (δ¹³C value shifts from -2.3‰ to 2‰) occurs near the boundary between the Qingxudong and Aoxi formations, close to the traditional Lower-Middle Cambrian boundary. The second excursion (δ¹³C value shifts from 0‰ to 3‰) occurs in the interval between the Linguagnostus reconditus Zone and the Glyptagnostus reticulatus Zone. The base of the G. reticulatus Zone define the base of the Paibi Stage and Furongian Series. Similar C isotope excursions also occur in shallow - water carbonate sections in North China. In Jiagou section near Huainan (Anhui Province), recently considered an important interval for defining the lower-middle Cambrian boundary because of dramatic changes in the trilobite fauna (extinction of redlichiids and appearances of ptychopariids), a negative C isotope excursion (δ¹³C value shifts from +1.21‰ to -1.93‰) occurs at the top of the lower member of the Mantou Formation. In the Gushan section (Changqing County, Shandong Province), a C isotope excursion (δ¹³C value shifts from -0.04‰ to 2.23‰) occurs at the base of the Changshan Formation and is coincident with the base of the Chuangia Zone. This excursion can be correlated with the excursion in the lower part of Glyptagnostus reticulatus Zone in the Wangcun section. The above two distinct C isotope excursions, which occur both in slope carbonates in South China and in shallow - water carbonates in North China, have also been recognized in Cambrian sections on other continents, and they coincide with global mass extinctions of trilobites. The two excursions evidently reflect global changes of Cambrian sea level, and they have utility for Cambrian subdivisions and for both regional and global stratigraphic correlation. In addition, a negative carbon excursion below the base of the Ptychagnostus atavus Zone in the Wangcun section supports previous suggestions that the FAD of P. atavus can be considered as a global correlatable horizon within the middle Cambrian.     

The Simonsen Site: Report For the Summer Of 1959

Abstract

Isolated surface finds of probable Archaic and Paleo-Indian sites have been made in western Iowa for the past decade. Recently 3 sites have been found in this area, along tributaries of the Missouri River, containing cultural material buried in sediments 13-17 feet below the modern surface. One of these sites, the Simonsen, exposed on a loop of the Little Sioux River, is described.

Bison bones were eroding below the top of an alluvial terrace. This profile is divided into 8 stratigraphic zones, Zones 1 and 2, were 9 feet thick and composed of sterile loam, sand and gravels. Zone 3, contained several disintegrated bison bones, fine ash, burned earth, a fire pit with charred log fragments and a hearth containing a large canid but no artifacts. Zone 4, 1-2 feet thick was composed of sterile interbedded gravels and sand. Zone 5, from a few inches to 2 feet thick contained small flecks of charcoal, and a fragment of a projectile point. Zone 6 was a very stilty sand interbedded with sand silts. Zone 7, 2-3 feet thick was the most profilic source of cultural material but considering the large area exposed, produced few artifacts. These were knives, flakes, 2 anvil stones and 3 points. Zone 8, a gravelly deposit of unknown thickness, underlay the cultural deposits.

A total of 7 bison skulls or partial skulls were collected in addition to abundant remains of other parts of the skeletons. These remains were tentatively assigned to the extinct specie, Bison occidentalis. Measurements of the metapoidals of these specimens agreed in massiveness with those from Scottsbluff and were smaller than specimen from the Brewster and Lipscomb sites which contained bison antiquus and Folsom artifacts.

The 1959 collection from the Simonsen site supports earlier observations of affiliations with the Logan Creek Site of Nebraska and argues for assignment within the late Paleo-Indian to early Archaic horizon.     

A Preliminary Study on Vegetation and Climate Changes in Dianchi Lake Area in the Last 40000 Years

This paper presents results of pollen analysis on sediments of core Cao 2 from Dianchi Lake. Four pollen zones are defined, namely zone I, which is further divided into four subzones, zone Ⅱ, zone Ⅲ and zone Ⅳ. Zone Ⅰ(ca. 47600–11800 yrs B. P.) is characterized by low land pollen sedimentation rates and constant presence of Abies pollen. In zone Ⅱ (ca. 11800–6900 yrs B. P.) broad-leaved tree pollen increases and Abies pollen gradually disappears. In zone Ⅲ (ca. 6900–3800 yrs B. P.) evergreen broad-leaved-tree pollen and total land pollen influx reach their maximum values while, Tsuga pollen decreases. Zone Ⅳ shows a great decreases in pollen influx of various pollen types and a increase in Monolete psilate spores. In the past 40000 years vegetation in this area trend changes from a dominantion of coniferous tree to an evergreen broad-leaved forest, co-existing or mixing deciduous broadleaved forest and coniferous forest. In the past 3800 years, due to climate changes and / or human activities, the vegetation cover in this area has been greatly reduced. The above vegetation changes indicate a climate change process from cool and humid, to warm and humid and finally to mild and dry.     

The basalis of the primate endometrium: a bifunctional germinal compartment

Radioautographic analysis of epithelial and stromal cell proliferation in the primate endometrial functionalis and basalis (rhesus monkey) has identified horizontal zonal patterns of mitotic activation and inhibition during natural menstrual cycles. At 1 h after a single i.v. injection of [3H]thymidine, mitotic activity in endometrial biopsies (hysterotomy) was determined on 9 days from the late proliferative to the late luteal phase (-2 days to + 14 days relative to the estrogen [E2]peak). Labeling indices (LIs) were determined within glandular segments of the 4 horizontal endometrial zones: Transient functionalis Zone I (luminal epithelium) and Zone II (uppermost gland); Germinal basalis: Zone III (middle gland) and Zone IV (basal gland). The size of the dividing epithelial populations (LI) differed zonally. During E2 dominance (-2 days to +3 days), the epithelial LIs of functionalis I (10 +/- 0.3%) and II (9.8 +/- 1.0%) were greater than those of basalis III (5.8 +/- 0.2%) and basalis IV (3.7 +/- 0.8%). During progesterone (P) dominance (+5 days to +14 days), epithelial mitosis was strongly inhibited in functionalis I (4.3 +/- 1.9%), functionalis II (0.8 +/- 0.2%), and basalis III (1.4 +/- 0.5%). Thus germinal basalis III was linked functionally with transient functionalis I and II by periovulatory uniformity in epithelial proliferation and postovulatory mitotic inhibition. A unique mitotic pattern set basalis IV apart from other zones by a steady rise in LI from 1% (-2 days) to 11% (+10 days). The LIs for stromal fibroblasts remained quite uniform in basalis IV but varied in other zones. Thus the postovulatory primate basalis was a distinct bipartite compartment in which the mitotic rate in basalis IV glandular epithelium increased steadily whereas that of basalis III was strongly inhibited. The remarkable enhancement of epithelial mitotic activity in basalis IV may reflect expansion of the stem-progenitor cell population for gestational growth or for post-menstrual regeneration.     

Health risk assessment in children living in an urban area with hydrofluorosis: San Luis Potosí Mexico case study

BackgroundFluoride is an inorganic element, which can be found in high concentrations in groundwater. Its consumption and exposure have consequences on human health. The objective of this study was to evaluate fluoride exposure and develop a health risk assessment in children from an urban area with hydrofluorosis in Mexico.MethodsWater fluoride levels in active wells were provided by the Water State Agency and divided into three zones: agriculture zone (Zone A), metallurgical zone (Zone B), and industrial zone (Zone C). Urinary fluoride levels were determined by potentiometric method using an ion-selective electrode. Health risk assessment was performed through Monte Carlo model analysis and hazard quotient was calculated.ResultsAccording to fluoride well concentration, all zones have high concentration especially Zone B (2.55 ± 0.98 mg/L). Urinary fluoride concentrations were highest in children in Zone B (1.42 ± 0.8 mg/L). The estimated median daily intake dose of fluoride was 0.084 mg/Kg-day for the children living in zone B. The highest mean HQ value was to Zone B (1.400 ± 0.980), followed by Zone C (0.626 ± 0.443).ConclusionThe levels of fluoride exposure registered are a potential risk to generate adverse health effects in children in the San Luis Potosi metropolitan area.