细粒沉积物多组分粒度特征及其成因机制研究

By using high-resolution laser grain size instrument Mastersizer 2000, the grain size distribution of windblown depositions (loess and sandy dunes), aqueous sediments (lake, river, riverside and foreshore sand), weathering crust, sloping materials and other fine-grain sediments are systemically measured. The multimodal characteristics of grain size distribution of these sediments are carefully studied. The standard patterns and their grain size characteristics of various sediments are systemically summarized. The discrepancies of multimodal distribution among windblown depositions, aqueous sediments and other sediments are concluded and the physical mechanisms of grain size multimodal distribution of various sediments are also discussed in this paper. The major conclusions are followed: 1. The multimodal characteristic of grain size distribution is a common feature in all sediments and results from properties of transportation medium, dynamic intensity, transportation manner and other factors. 2. The windblown depositions are controlled by aerodynamic forcing, resulting in that the median size of the predominant mode gradually decreases form sandy dunes to loess. Similarly, the aqueous sediments are impacted by dynamic forces of water currents and the median grain size of the predominant mode decreases gradually from river to lake sediments. Because the kinetic viscidity of air is lower than of water, the grain size of modes of windblown depositions is usually finer than that of corresponding modes of aqueous sediments. Typical characteristics of sediments grain size distribution of various sediments have been summarized in the paper: (1) Suspended particles which diameters are less than 75μm are dominant in loess and dust. There are three modes in loess’ grain size distribution: fine, median and coarse (the median size is <1μm、1-10μm、10-75μm, respectively). The coarse mode which percentage is larger than that of others is controlled by source distance and aerodynamic intensity of dust source areas. Some samples also have a saltation mode which median size is about 300-500μm. Our analysis demonstrates that the interaction of wind, atmospheric turbulence, and dust grain gravity along the dust transportation path results in a multimodal grain size distribution for suspended dust. Changes in the median sizes of the coarse and medium modes are related to variation in aerodynamic forcing (lift force related to vertical wind and turbulence) during dust entrainment in the source area and turbulence intensity in the depositional area. (2) There is a predominant coarse saltation mode in grain size distribution of sandy dunes, which median size is about 100-300μm and the content is larger than that of other modes. The grain size distribution curve is near axis symmetric as a standard logarithm normal function. There are some suspended particles in some samples of sandy dunes, which distribution of the fine part is similar to that of loess. Comparing with sandy samples of river sediments, the sorting property of sandy dunes is better than of river samples although both they are the saltation mode. Thus, the sorting property is a criterion to distinguish dune sands and river sands. (3) There are 5~6 modes (median size are <1μm, 1-10μm, 10-70μm, 70-150μm, 150-400μm, >400μm respectively) in grain size distribution of lacustrine sediments. The former 4 modes are suspensive and others are saltated. Lacustrine sediments can be divided into three types: lake shore facies, transitional facies and central lake facies. The grain size distributions of the three facies are distinctly different and, at the same time, the transition among three modes is also clear. In all these modes, the third mode is a criteria to identify the windblown deposition in the watershed. In lake shore sediments, suspended particles are dominant, a saltation mode sometimes occurs and the fourth mode is the most important mode. In the transitional facies, the percentage of the fourth mode decreases and that of the second mode increases from lake shore to central lake. In the central lake facies, the second mode is dominant. A higher content of the second mode indicates its position more close to the central lake. (4) The grain size distribution of river sediments is the most complex. It consist of suspension, saltation and rolling modes. In most situations, the percentage of the saltation mode is larger than that of other modes. The percentage of suspension modes of river sediments is more than of sandy dunes. The grain size distribution of river sediments indicates dynamic strength of river currents. If the fourth mode is dominant, the dynamic forcing of river is weaker, such as in river floodplain. If the five or sixth mode is dominant, the water dynamic forcing of rivers is strong. (5) Sediments can be changed by later forcing in different degree to form some complicated deposition types. In the paper, the grain size distribution of aqueous sediments of windblown deposition, windblown sediments of aqueous deposition, weathering crust and slope materials are discussed and analyzed. 3. The grain size distribution characteristics of different sediments are concluded: (1) Modal difference: Usually there are suspended and saltation modes in the windblown deposition. The third mode is dominant in loess dust and the fifth mode is predominant in sandy dunes. There are suspended, saltation and rolling particles in aqueous sediments. In lacustrine sediments, the second and fourth mode are predominant for central lake facies or lake shore facies, respectively. In river sediments, the fourth, or fifth, or sixth mode is predominant. Suspended modes: the grain size of suspended particles of windblown depositions usually is less than 75μm. The content of suspended particles is lower or none in sandy dunes. However, suspended particles of aqueous sediments may reach 150μm. Difference in grain size of suspended modes represents difference between transitional mediums and the strength of dynamic forcing. Saltation modes: the median size of saltation mode of sandy dunes fluctuates less than that of river sediments. (2) Loess dust and lacustrine sediment: Their suspended particles are clearly different. There is an obvious pit between the second and the third modes in grain size distribution of lacustrine sediments. The phenomenon doesn’t occur in loess dust. In lacustrine sediments, the second mode can be a dominant mode, such as central lake facies, and contents of the second and the third modes change reversely. However, the percentage of the third mode is always the highest in loess dust. (3) Dune Sand and fluvial sand: In these two depositions, the saltation particles are dominant and the median sizes of their saltation modes overlay in distribution range. The fifth mode of dune sand fluctuates is sorted better than that of fluvial sand. (4) Lacustrine and fluvial sediments: In lacustrine sediments, there are 5-6 modes and suspended particles can be predominant. The second mode is dominant in central lake facies and the third mode is dominant in lake shore facies. Saltation or roll modes occurred in central lake facies may indicate strong precipitation events. In fluvial sediments, saltation particles (or rolling particles) usually dominant. 4. A estimation model of lake depth is firstly established by using contents of the second, the third and the fourth modes. 5. The paleoenvironmental history of the eastern part of SongLiao basin is also discussed by analyzing the grain size distribution of Yushu loess-like sediments in Jilin. It was found that there is a tectonic movement before 40ka B.P. in SongLiao basin. After the movement, loess dust deposited in Yushu area as keerqin desert developed. In recent 2000 years, the climate became drier and more deserts activated in the eastern part of Song-Liao basin.

蒙古国宗巴音凹陷沉积相研究及优质储层预测

Abstract:Little fundamental work on petroleum exploration and production of Zuunbayan Subbasin, Mongolia has been done before because of the backward economy and petroleum industry techniques in this country, which also results in our little knowledge of reservoir characteristics of this area. This paper focused on the sedimentary system, sedimentary facies, reservoir characteristics and their genesis distribution of Zuunbayan subbasin with various drilling, well logging, seismic, coring and outcrop data, aiming at providing significant guidances for the petroleum exploration and production of Zuunbayan area. Therefore, several conclusions have been achieved as follows: ①In Zuunbayan Subbasin, there are two chief source areas with Tarkhyata and Totoshan Uplifts in the southeast and Saykhandulaan Uplift in the west, respectively, while two subsidiary ones in the northeast and southwest of this subbasin. The sedimentary system of alluvial fan-fan delta is formed in the southeast highland, meanwhile braided river-braided river delta develops in the western ramp region and fan delta in the southern palaeohigh. ②There are middle to high permeability reservoirs in the upper Zuunbayan Formation and the upper member of lower Zuunbayan Formation meanwhile low-porosity and permeability to ultra-low permeability ones in Tsagaan Tsav Formation and the middle and lower members of lower Zuunbayan Formation. Combing with sedimentary facies belt, oil sources conditions and tectonic settings, favorable reservoir belts have been proved to be existing in the fan delta front reservoirs of lower Zuunbayan – Tsagaan Tsav Formation in the central uplift faulted zone as well as the braided river front ones of lower Zuunbayan-Tsagaan Tsav Formation in Zuunbayan nose anticlinal structural belts. ③The reservoir lithologic composition is complex and also related to volcanic activities. Generally, the types of lithologic composition in Zuunbayan Subbasin are chiefly feldspathic litharenites with low compositional maturity and high-middle textural maturity. The rock constituents from upper Cretaceous to lower Zuunbayan Formation are mainly metamorphic rocks including cleaving stone, phyllite, quartzite and schist while volcanic tuffs and acidic extrusive rocks are the secondary; and in the Tsagaan Tsav Formation are mainly volcanic tuffs with subsidiary cleaving stone, phyllite, quartzite and schist. ④In this paper, high-quality reservoirs in the upper member of lower Zuunbayan Formation have been discovered in the drilled high production wells of favorable reservoir facies through sedimentary system and sedimentary facies research, which benefits the prospect and also will bring a new life for petroleum exploration and production of Zuunbayan Subbasin. Key words: sedimentary system, sedimentary facies, superior quality reservoir, Zuunbayan Subbasin, lower Zuunbayan Formation

陇西盆地晚第三纪风尘沉积的地层学研究

In Asia, the significant environment changes in Cenozoic include: uplift of Himalayas and Tibetan Plateau, formation Asian monsoon system, Aridification in Central Asia. One of major advances in recent studies of eolian deposit on the Loess Plateau is the verification of the eolian origin for the Late Tertiary Hipparion Red-Earth (also called red-Clay) underlying the Quaternary loess. Thus, the Late Tertiary eolian deposit, which has been proven a nearly continuous terrestrial record and sensitive to climate change, provides us an important archive to understand these above Cenozoic environment events. The deposit in eastern Loess Plateau has been extensively studied, while the property and age of deposit underlying the Quaternary loess in western plateau remains unclear. In this paper, detail investigations were made on the Sedimentology, geochemistry of Longxi section, a typical section in western Loess Plateau, to address its origin, and on micromammalian fossils and magnetostratigraphy to address its age. The main conclusions are presented as following: 1. The sedimentological and geochemical properties in Longxi section are highly similar to typical Quaternary eolian deposit in Loess Plateau. Nearly 100 paleosols are recognized in the field, and the grain size are very fine with the median grain size centered at 4～7μm. There is a good agreement of both major and trace element compositions between Longxi deposit and the Quaternary Loess. The REE distribution patterns of Longxi deposit and the Quaternary loess are remarkably similar in shape, with enrichment LREE and fairly flat HREE profiles and clear negative Eu anomaly. The mangnetic minerals in Longxi deposit are mainly magnetite, hematite and maghematite, which are similar to those of the Hipparion Red-Earth and Quaternary Loess. The major difference among them is that the samples from Longxi section contain more hematite. The characteristics of anisotropy of magnetic susceptibility (AMS) in Longxi deposit is highly consistent with that of Quaternary loess, while values of the major AMS parameters, e.g. anisotropy degree, magnetic foliation and lineation, are significantly lower than those of fluvial and lake deposits. These evidences indicate an eolian origin for the sediment. 2. An investigation of micromammalian fossils was firstly carried out for determining the approximate age of the sequence because of lack of materials for accurate isotope dating. Three fossil assemblages were obtained which indicate a chronological range from the Middle Miocene to Late Miocene. The magnetostratigraphical study suggests that it is a near continuous terrestrial record for the period from 13.23 to 6.23 MaB.P. The obtained chronology is highly consistent with fossils assemblages. This section is the oldest eolian deposit presently known in Loess Plateau. 3. The magnetic susceptibly value is high in paleosols than in surrounded weak-weathered layers, which suggests that it may be a climate index on orbital time scale. While it cannot be used as a proxy to address the long-term, change of climate on tectonic time scale, as content of the magnetic minerals is highly variable in different parts of the section. 4. The appearance of Middle Miocene eolian deposit in the Loess Plateau marks the strengthening of aridification of Central Asia. The high degree of similarity between the geochemical properties of Longxi eolian deposit, Hipparion Red-Earth and Quaternary loess a suggests that a rather similar source provenance. The dust accumulation rate (DAR) of Longxi section, which is widely used as a proxy to document the aridity in source areas in marine and terrestrial record studies, recorded the aridity condition in northwestern China over a period from Middle Miocene to Late Miocene. The DAR of the section shows that the continent aridity remains moderate and relative stable over that period.

准噶尔盆地三个泉凸起油气成藏条件及动力学研究

Sangequan Uplift in Junggar Basin is an inherited positive structure, which has undergone many times of violent tectonic movements, with high tectonic setting, and far away from the oil-source sag, reservoir forming condition is complex. Combining sequence stratigraphy, depositional facies, reservoir formation theory with seismic and well logging analysis, this paper conducted integrated study on the hydrocarbon migration, accumulation, entrapment conditions, the reservoir forming dynamics and the forming model, and acquired the following recognition: (1) The special reservoir formation conditions that enable Sangequan Uplift to form a giant oil-gas field of over 100 million tons of reserves are as follows: (D Deltaic frontal sandbody is developed in Jurassic Xishanyao Formation, Toutunhe Formation and Lower Cretaceous Hutubihe Formation, with good reservoir quality;? Abundant hydrocarbon resources are found in Western Well Pen-1 Sag, which provides sufficient oil sources for reservoir formation of Sagequan Uplift; ?The unconformity-fault-sandbody system has formed a favorable space transporting system and an open conduit for long-distance hydrocarbon migration; ?fault, low amplitude anticline and lithological traps were well developed, providing a favorable space for hydrocarbon accumulation. (2) The most significant source beds in the Western Well Pen-1 Sag are the Mid-Permian Lower Wuerhe Formation and Lower-Permian Fengcheng Formation. The oil in the Well Block Lu-9 and Shinan Oilfield all originated from the hydrocarbon source beds of Fengcheng Formation and Lower Wuerhe Formation in the Western Well Pen-1 Sag and migrated through Jidong and Jinan deep faults linking unconformity of different regions from sources to structural highs of the uplift and shallow horizons. (3) There were 2 reservoir formation periods in District Sangequan: the first was in late Cretaceous during which the upper part of Xishanyao Formation and Toutunhe Formation; the second was in Triassic, the main resources are high-maturity oil and gas from Fengcheng Formation and Wuerhe Formation in Western Pen-1 Well sag and the gas from coal measure strata of Xishanyao Formation, that were accumulated in Hutubihehe Formation. (4) Model of the hydrocarbon migration, accumulation, reservoir formation of the study area are categorized as three types starting from the hydrocarbon source areas, focusing on the faults and unconformity and aiming at reservoirs: ① Model of accumulation and formation of reservoir through faults or unconformities along the "beam" outside source; ②Model of migration, accumulation and reservoir formation through on-slope near source;③Model of migration, accumulation and reservoir formation of marginal mid-shallow burial biogas-intermediate gas. (5) Pinchout, overlap and lithologic traps are developed in transitional zones between Western Well Pen-1 sag and Luliang uplift. Many faulted blocks and faulted nose-like traps are associated with large structures on Sangequan uplift. Above traps will be new prospecting areas for further hydrocarbon exploration in future.

北京周边地区沙尘基的数值模拟与风成物质的REE分析

The sandstorms in 2001 were numerically simulated with NARCM that is a dust emission and transport model developed by Meteorological Service of Canada. In this paper, the dataset of NARCM model is processed and analyzed. The results of processing and analyzing show fair images about influence ranges and transport routes of sandstorms in 2001. The outcomes are compared with aerosol concentrations of atmosphere over Beijing, China and Tango, Japan. It confirms that sandstorm occurs when AK TK K and Si concentration in the air increases. It can be concluded that the NARCM model is appropriate for modeling sandstorm in North of China. The processing and analyzing show that the dust is produced and transported in the Otindag and Bashang. So the Otindag and Bashang are parts of source areas of sandstorms in East Asia. Another focus of this study is the REE of aeolian sediments in Otindag、Bashang、Tianmo Badain Jara、Hulunbeier and Kalahali, South Africa. The analysis on REE shows: There is clear distinction in HREE and LREE's Fractionation Degree (HLFD) between the deserts. HLFD is very high in Hulunbeier, with a value of (La/Lu)N 16.0. The value of (La/Lu)N is 12.7 inTianmo and 8.1 in Octindag. The HREE's Fractionation Degree(HFD) is about 4.0, quite similar in all samples. (3) The LREE's Fractionation Degree(LFD) varies slightly, from 1.5(Badain Jaran) to 2.3(Tianmo).

黄土高原粉尘堆积源区环境及风化历史初步研究

In this study, we examined the surface features of quartz grains, the quartz oxygen isotopic ratios and the mineralogical compositions of the loess - paleosol - red clay sediments systematically. The surface features of quartz grains do not show significant changes of the dust deposits through the past seven million years. The particles were mainly created in the process of glacial and frost weathering of high mountains. Then the surfaces were altered in some degree by the flood and wind abrasion. The surface features registered all these processes. The assemblages of surface features changed for four times in the past seven million years, the occurrence ages are: 5.0~4.2MaBP, about 3.6MaBP, about 2.6MaBP and about 0.9MaBP, respectively. This may indicate that there were uplift events of the Tibetan Plateau during those times. The oxygen isotopic compositions of quartz in the sediments represent the oxygen isotopic compositions of the initial dusts because of the stable properties of quartz both physically and chemically. The oxygen isotopic compositions of 4~16um quartz changed significantly at about 2.6MaBP, decreasing from about 19.5%o to about 18.5%o. This decrease of quartz oxygen isotopic ratio suggests that the environments of the dust source areas changed at that time, or the range of dust source area changed at that time. The environmental change may result from the structural evolution of the Tibetan Plateau and global cooling at that time. The coarse fractions (>30μm) of the dust deposits were examined using the EDXA device for mineral identification. The quartz content has a decrease trend during 7~2MaBP, then increase rapidly at about 2MaBP. After 2MaBP, quartz content continues to decrease. The Ca-plagioclase content / quartz content ratio increase at about 3.6MaBP. The ratio shows a peak of 3-6 fold values at about 2.5~1.8MaBP, the cause of this is still unknown. The Ca-plagioclase content / quartz content ratio continues to increase after 1 MaBP. The flowing can be regarded as the conclusion remarks of this study: Some of the red clay sediment of the Chinese Loess Plateau (at least Lingtai and Jingchuan red clays) is eolian in origin. The quartz grains from dust deposits throughout the past seven million yeas showed the clues of glacial and frost processes. This indicates that the high mountains of western China reached a certain altitude to favor the glacial and/or frost processes at least seven millions years before. The weathering intensities of the past seven nnillion yeas have a decreasing trend. In about 5~4.5MaBP, the weathering is relatively weak, and the dust supply is relatively low. At about 3.6MaBP and 2.6MaBP, the dust supply increased significantly. The mineralogical composition, the quartz surface feature and the quartz oxygen isotope composition were influenced by the uplift of the Tibetan Plateau. The Plateau may have reached a certain altitude to generate the arid regions of inland China and favor the glacial and frost weathering. And it underwent a phased uplift, which have uplift events at about 3.6MaBP and 2.6MaBP.

松辽盆地河流-三角洲体系高分辩率层序地层学、储层构形及非均质模型研究

This dissertation tries to combine the new theories of high-resolution sequence stratigraphy and reservoir architecture with fine sedimentology to form a integral theory system -"high-resolution sequence sedimentology", which can be applied widely ranging from the early petroleum exploration to the tertiary recovery stage in marine and terrestrial basin. So the west slope area in south of Songliao basin, in which, early-fine exploration have been developed, and Xingnan area of Daqing placantictine in high water-bearing and tertiary recovery stage, are selected as target areas to research and analyze. By applying high-resolution sequence stratigraphy theory as well as analysis of source area-facies, the west slope area has been divided into two source areas and three drainage systems and the following conclusions have been drawn: three high values sandstone areas, two sandstone pinchout zones and one stratigraphic pinchout overlap; the facies between Baicheng-Tongyu drainage system is frist ascertained as large-scale argillaceous filled plain facies; fine-grained braided channel-delta depositional system has been found; plane sedimentary facies and microfacies maps of different-scale sequence have been completed, and then twenty-eight lithologic traps have been detected in the east of Taobao-Zhenlai reverse fault zone; In no exploration area of the west, large-scale stratigraiphic overlap heavy oil reservoirs has first been found, which has become an important prograss. In Xingnan area, in the view of high-resolution sequence stratigraphy, the surface of unconformity (the bottom of SSC13) in P I group has been identified, and the following method and technique have been advanced: the division and correlation methods of short-scale base-level cycle sequence (SSC); the comprehensive research methods of SSC plane microfacies; the division technique of hierarchy and type of flow unit, the origin of large-scale composite sandbody and flow unit; And ,on the basis of these, 103 monosandstone bodies and 87 flow units of the third levels have been identified, and four levels of flow units model of five sandstone-bodies types have been established. Because it is a very difficult task all over the world to research architecture in subsurface monosandstone body, brings forward a series of techniques as follows: technique of researching architecture of thin interbed in subsurface monosandstone body; classification, type and liquid-resisting mechanism of thin interbed; multiple-remember vertical subsequence model of remaining oil in monosadstone body. Models of heterogeneity and architecture of thin interbed in five types of monosandstone body have been established. Applying these techniques, type and distribution of remaining oil in different types of monosandstone bodies have been predicated.

Pathways for delivery of surface water nutrients to receptors

Diffuse contaminants can make their way into rivers via a number of different pathways, including overland flow, interflow, and shallow and deep groundwater. Identification of the key pathway(s) delivering contaminants to a receptor is important for implementing effective water management strategies. The ‘Pathways Project’, funded by the Irish Environmental Protection Agency, is developing a catchment management tool that will enable practitioners to identify the critical source areas for diffuse contaminants, and the key pathways of interest in assessing contaminant problems on a catchment and sub-catchment scale.
One of the aims of the project is to quantify the flow and contaminant loadings being delivered to the stream via each of the main pathways. Chemical separation of stream event hydrographs is being used to supplement more traditional physical hydrograph separation methods. Distinct, stable chemical signatures are derived for each of the pathway end members, and the proportion of flow from each during a rainfall event can be determined using a simple mass balance approach.
Event sampling was carried out in a test catchment underlain by poorly permeable soils and bedrock, which is predominantly used for grazing with a number of one-off rural residential houses. Results show that artificial field drainage, which includes subterranean land drains and collector drains around the perimeters of the 1 to 10 ha fields, plays an important role in the delivery of flow and nutrients to the streams in these types of hydrogeological settings.
Nitrate infiltrates with recharge and is delivered to the stream primarily via the artificial drains and the shallow groundwater pathway. Longitudinal stream profiles show that the nitrate load input is relatively uniform over the 8 km length of the stream at high flows, suggesting widespread diffuse contaminant input. In contrast, phosphorus is adsorbed in the clay-rich soil and is transported mainly via the overland flow pathway and the artificial drains. Longitudinal stream profiles for phosphorus suggest a pattern of more discrete points of phosphorus inputs, which may be related to point sources of contamination.
These techniques have application elsewhere within a toolkit of methods for determining the key pathways delivering contaminants to surface water receptors.

Exceptionally Long Distance Transport of Volcanic Ash: Implications for Stratigraphy, Hazards and the Sourcing of Distal Tephra Deposits

Cryptotephras (tephra not visible to the naked eye) form the foundation of the tephrostratigraphic frameworks used in Europe to date and correlate widely distributed geologic, paleoenvironmental and archaeological records. Pyne-O'Donnell et al. (2012) established the potential for developing a similar crypto-tephrostratigraphy across eastern North America by identifying multiple tephra, including the White River Ash (east; WRAe), St. Helens We and East Lake, in a peat core located in Newfoundland. Following on from this work, several ongoing projects have examined additional peat cores from Michigan, New York State, Maine, Nova Scotia and Newfoundland to build a tephrostratigraphic framework for this region. Using the precedent set by recent research by Jensen et al.(in press) that correlated the Alaskan WRAe to the European cryptotephra AD860B, unknown tephras identified in this work were not necessarily assumed to be from "expected" source areas (e.g. the Cascades). Here we present several examples of the preservation of tephra layers with an intercontinental distribution (i.e. WRAe and Ksudach 1), from relatively small magnitude events (i.e. St. Helens layer T, Mono Crater), and the first example of a Mexican ash in the NE (Volcan Ceboruco, Jala pumice). There are several implications of the identification of these units. These far-travelled ashes: (1) highlight the need to consider "ultra" distal source volcanoes for unknown cryptotephra deposits,. (2) present an opportunity for physical volcanologists to examine why some eruptions have an exceptional distribution of ash that is not necessarily controlled by the magnitude of the event. (3) complicate the idea of using tephrostratigraphic frameworks to understand the frequency of eruptions towards aiding hazard planning and prediction (e.g. Swindles et al., 2011). (4) show that there is a real potential to link tropical and mid to high-latitude paleoenvironmental records. Jensen et al. (in press) Transatlantic correlation of the Alaskan White River Ash. Geology. Pyne-O'Donnell et al. (2012). High-precision ultra-distal Holocene tephrochronology in North America. Quaternary Science Reviews, 52, 6-11. Swindles et al. (2011). A 7000 yr perspective on volcanic ash clouds affecting northern Europe. Geology, 39, 887-890.

DPSIR framework application supported by integrated watershed modeling for irrigation from Alqueva dam (Portugal) on Guadiana river estuary

Dissertação de mest., Gestão da Água e da Costa, Faculdade de Ciências e Tecnologia, Universidade do Algarve, 2009

Long-range Transport of Ambrosia Pollen to Poland

The long-range transport of Ambrosia pollen to Poland is intermittent and mainly related to the passage of air masses over the Carpathian and Sudetes mountains. These episodes are associated with hot dry weather, a deep Planetary Boundary Layer (PBL) in the source areas and winds from the south. Such episodes can transport significant amounts of Ambrosia pollen into Poland. The study investigates Ambrosia pollen episodes at eight sites in Poland during the period 7th to 10th September 2005, by examining temporal variations in Ambrosia pollen and back-trajectories. PBL depths in the likely source areas were calculated with the Eta meteorological model and evaluated against the mountain heights. Considerable amounts of Ambrosia pollen were recorded at several monitoring sites during the night or early in the morning of the investigated period. Trajectory analyses shows that the air masses arriving at the Polish sites predominantly came from the south, and were in the Czech Republic, Slovakia and Hungary the previous day indicating these countries as potential source areas. We have shown the progress of Ambrosia plumes into Poland from the south of the country, probably from Slovakia and Hungary, and demonstrated how Lagrangian back-trajectory models and meteorological models can be used to identify possible transport mechanisms of Ambrosia pollen from potential source regions.

A Mechanism For Long Distance Transport of Ambrosia Pollen From the Pannonian Plain

The pollen grains of ragweed are important aeroallergens that have the potential to be transported longdistances through the air. The arrival of ragweed pollen in Nordic countries from the Pannonian Plain canoccur when certain conditions are met, which this study aims to describe for the first time. Atmosphericragweed pollen concentrations were collected at 16 pollen-monitoring sites. Other factors included inthe analysis were the overall synoptic weather situation, surface wind speeds, wind direction and tem-peratures as well as examining regional scale orography and satellite observations. Hot and dry weatherin source areas on the Pannonian Plain aid the release of ragweed pollen during the flowering seasonand result in the deep Planetary Boundary Layers needed to lift the pollen over the Carpathian Moun-tains to the north. Suitable synoptic conditions are also required for the pollen bearing air masses tomove northward. These same conditions produce the jet-effect Kosava and orographic foehn winds thataid the release and dispersal of ragweed pollen and contribute towards its movement into Poland andbeyond.

Using non-invasive techniques to examine black bear (Ursus americanus) abundance in the North Cascades Ecosystem, Washington State

Thesis (Master's)--University of Washington, 2013

Potential Sources of Airborne Alternaria spp. spores in South-west Spain

Fungi belonging to the genus of Alternaria are recognised as being significant plant pathogens, and Alternaria allergens are one of themost important causes of respiratory allergic diseases in Europe. This study aims to provide a detailed and original analysis of Alternaria transport dynamics in Badajoz, SW Spain. This was achieved by examining daily mean and hourly observations of airborne Alternaria spores recorded during days with high airborne concentrations of Alternaria spores (N100 s m−3) from 2009 to 2011, as well as four inventory maps of major Alternaria habitats, the overall synoptic weather situation and analysis of air mass transport using Hybrid Single Particle Lagrangian Integrated Trajectory model and geographic information systems. Land use calculated within a radius of 100 km from Badajoz shows that crops and grasslands are potentially the most important local sources of airborne Alternaria spores recorded at the site. The results of back trajectory analysis showthat, during the examined four episodes, the two main directions where Alternaria source areas were located were: (1) SW–W; and (2) NW–NE. Regional scale and long distance transport could therefore supplement the airborne catch recorded at Badajoz with Alternaria conidia originating from sources such as crops and orchards situated in other parts of the Iberian Peninsula.

The Long Distance Transport of Airborne Ambrosia Pollen to the UK and the Netherlands from Central and South Europe

Background: The invasive alien species Ambrosia artemisiifolia (common or short ragweed) is increasing its range in Europe. In the UK and the Netherlands airborne concentrations of Ambrosia pollen are usually low. However, more than 30 Ambrosia pollen grains per cubic metre of air (above the level capable to trigger allergic symptoms) were recorded in Leicester (UK) and Leiden (NL) on 4 and 5 September 2014. Objective: The aims of this study were to determine whether the highly allergenic Ambrosia pollen recorded during the episode could be the result of long distance transport, to identify the potential sources of these pollen grains and describe the conditions that facilitated this possible long distance transport. Methods: Airborne Ambrosia pollen data were collected at 10 sites in Europe. Back trajectory and atmospheric dispersion calculations were performed using HYSPLIT_4. Results: Back trajectories calculated at Leicester and Leiden show that higher altitude air masses (1500m) originated from source areas on the Pannonian Plain and Ukraine. During the episode, air masses veered to the west and passed over the Rhône Valley. Dispersion calculations showed that the atmospheric conditions were suitable for Ambrosia pollen released from the Pannonian Plain and the Rhône Valley to reach the higher levels and enter the air stream moving to Northwest Europe where they were deposited at ground level and recorded by monitoring sites. Conclusions: The study indicates that the Ambrosia pollen grains recorded during the episode in Leicester and Leiden were probably not produced by local sources, but transported long distances from potential source regions in East Europe, i.e. the Pannonian Plain and Ukraine, as well as the Rhône Valley in France.