Regional Source Areas Research Articles

Evaluating the Distributions and Impacts of Macroplastic Pollutants in Agansa Coastal Community, South Eastern Nigeria

The distributions and impacts of macroplastic pollutants in Agansa coastal Community, Southeastern Nigeria was studied. Samplings of floating marine debris or macroplastics in the water column were collected using nets towing, while hand-picking method was adopted at the shore by marking a 5 by 5 meter gridded section for samples counting and collection. The collected plastic debris was transferred to the laboratory for sorting and weighing. The results showed a mean abundance of plastic debris in the study areas in respect to the month. The composition of plastic debris ranged in size mainly from 1 to 20 cm. In terms of composition, plastic bottles was the most common and abundant (12.7%), followed by packaging plastics (11.2%), sachets (9.8%), nylon (6.2%), fishing equipments (5.8%), and many others. The weight of plastic debris in the study areas ranged from 5.3 to 17.5grams. Moreover, the plastic debris significantly correlated both positively and negatively at (p < 0.01) and (p < 0.05) level. Some physicochemical parameters of surface water in the study area were high in the upstream than downstream. From the mean evaluation, total dissolved solids (TDS) >Temperature >Salinity>total suspended solids (TSS) > pH >dissolved oxygen (DO) >Turbidity in the months of January and March. The result of the statistical analysis shows both significant and no significant difference (p<0.05) between the parameters and months. This study provided a method to quantify the inventory of plastic debris on a beach. The tidal variation and human activities were responsible for the plastic debris accumulation. Hence, this study could be helpful to consider regional tidal variations and critical source areas for effective plastic debris clean-up.

Seasonal Distribution, Composition, and Inventory of Plastic Debris on the Yugang Park Beach in Zhanjiang Bay, South China Sea.

Plastic debris contamination in marine environments is a global problem that poses a considerable threat to the sustainability and health of coastal ecosystems. Marine beaches, as the key zones where terrestrial plastic debris reach coastal waters, are faced with the increasing pressures of human activities. In this study, we explored the distribution, composition, and inventory of plastic debris over seasonal and tidal zones at the Yugang Park Beach (YPB) in Zhanjiang Bay, South China Sea, to provide a baseline for plastic debris on a marine beach. The results showed mean abundance of plastic debris in summer (6.00 ± 2.10 items/m2) was significantly greater than that in winter (3.75 ± 2.12 items/m2). In addition, the composition of plastic debris ranged in size mainly from 1 to 5 mm and 0.5 to 2.5 cm in winter and summer, respectively. In terms of composition, white plastic debris was the most common (81.1%), and foam was the most abundant (64.4%). Moreover, there was a significant relationship between the abundance of plastic debris and sand grain size fraction (p < 0.05), implying the abundances of microplastic debris were more easily impacted by sand grain size (>2 mm). In total inventory, there were about 1.18 × 105 and 2.95 × 105 items of plastic debris on the YPB in winter and summer, respectively. The tidal variation and human activities are responsible for the plastic debris accumulation. This study provided a method to quantify the inventory of plastic debris on a beach and could be helpful to consider regional tidal variations and critical source areas for effective plastic debris clean-up.

A 10Be-dated record of glacial retreat in Connemara, Ireland, following the Last Glacial Maximum and implications for regional climate

Late Pleistocene stadials are traditionally viewed as periods of severe, year-round cooling centred on the North Atlantic, where the abrupt onset and termination of stadial conditions is widely, though not unequivocally, thought to reflect the impact on Atlantic Meridional Circulation of meltwater fluxes from fringing ice masses. Widespread subaerial melting of land-based ice, however, implies a state of glacier-climate disequilibrium that, according to some conceptual models, had to persist for the duration of each stadial event rather than immediately prior to it. Yet, to date, the spatial extent of any such melting remains unclear, as do the magnitude and duration of any cognate atmospheric warming. To help address this ambiguity, we reconstructed the timing and nature of deglaciation of the Connemara ice centre, Ireland, which, being located immediately downwind of the North Atlantic, affords an ideal location for assessing terrestrial expressions of stadial and non-stadial conditions. We report 15 new cosmogenic beryllium-10 ages of glacial erratic boulders that reveal the timing and magnitude of fluctuations in this sector of the former Irish ice sheet during Heinrich Stadial 1 (HS1). Coupled with geomorphic mapping, these results indicate rapid, widespread deglaciation of the Connemara ice centre at approximately 17 ka, under full stadial conditions, and that the ice margin retreated back to regional source areas rather than eastward towards the centre of the island. Recognising the potential divergence from the traditional view of cold North Atlantic stadials, we propose that the rate and nature of deglaciation in Connemara during HS1 likely reflects enhanced subaerial melting during the summer ablation season. • Fifteen new 10 Be dates constrain the deglaciation of an ice centre in Connemara, Ireland to Heinrich Stadial 1. • Our chronology contrasts with the current paradigm and suggests summer melting occurred despite anomalous winter cooling. • The Connemara deglacial record supports a broader pattern of enhanced seasonality in the North Atlantic during stadials.

Heavy and Light Mineral Association of Late Quaternary Permafrost Deposits in Northeastern Siberia

We studied heavy and light mineral associations from two grain-size fractions (63–125 μm, 125–250 µm) from 18 permafrost sites in the northern Siberian Arctic in order to differentiate local versus regional source areas of permafrost aggradation on the late Quaternary time scale. The stratigraphic context of the studied profiles spans about 200 ka covering the Marine Isotope Stage (MIS) 7 to MIS 1. Heavy and light mineral grains are mostly angular, subangular or slightly rounded in the studied permafrost sediments. Only grains from sediments with significantly longer transport distances show higher degrees of rounding. Differences in the varying heavy and light mineral associations represent varying sediment sources, frost weathering processes, transport mechanisms, and post-sedimentary soil formation processes of the deposits of distinct cryostratigraphic units. We summarized the results of 1141 microscopic mineral analyses of 486 samples in mean values for the respective cryostratigraphic units. We compared the mineral associations of all 18 sites along the Laptev Sea coast, in the Lena Delta, and on the New Siberian Archipelago to each other and used analysis of variance and cluster analysis to characterize the differences and similarities among mineral associations. The mineral associations of distinct cryostratigraphic units within several studied profiles differ significantly, while others do not. Significant differences between sites as well as between single cryostratigraphic units at an individual site exist in mineral associations, heavy mineral contents, and mineral coefficients. Thus, each study site shows individual, location-specific mineral association. The mineral records originate from multiple locations covering a large spatial range and show that ratios of heavy and light mineral loads remained rather stable over time, including glacial and interglacial periods. This suggests mostly local sediment sources and highlights the importance of sediment reworking under periglacial regimes through time, including for example the formation of MIS 1 thermokarst and thermo-erosional deposits based on remobilized MIS 3 and 2 Yedoma Ice Complex deposits. Based on the diverse mineralogical results our study supports the viewpoint that Yedoma Ice Complex deposits are mainly results of local and polygenetic formations (including local aeolian relocation) superimposed by cryogenic weathering and varying climate conditions rather than exclusive long distance aeolian transport of loess, which would have highly homogenized the deposits across large regions.

Chemical Composition and Source Apportionment of Total Suspended Particulate in the Central Himalayan Region

The present study analyzes data from total suspended particulate (TSP) samples collected during 3 years (2005–2008) at Nainital, central Himalayas, India and analyzed for carbonaceous aerosols (organic carbon (OC) and elemental carbon (EC)) and inorganic species, focusing on the assessment of primary and secondary organic carbon contributions (POC, SOC, respectively) and on source apportionment by positive matrix factorization (PMF). An average TSP concentration of 69.6 ± 51.8 µg m−3 was found, exhibiting a pre-monsoon (March–May) maximum (92.9 ± 48.5 µg m−3) due to dust transport and forest fires and a monsoon (June–August) minimum due to atmospheric washout, while carbonaceous aerosols and inorganic species expressed a similar seasonality. The mean OC/EC ratio (8.0 ± 3.3) and the good correlations between OC, EC, and nss-K+ suggested that biomass burning (BB) was one of the major contributing factors to aerosols in Nainital. Using the EC tracer method, along with several approaches for the determination of the (OC/EC)pri ratio, the estimated SOC component accounted for ~25% (19.3–29.7%). Furthermore, TSP source apportionment via PMF allowed for a better understanding of the aerosol sources in the Central Himalayan region. The key aerosol sources over Nainital were BB (27%), secondary sulfate (20%), secondary nitrate (9%), mineral dust (34%), and long-range transported mixed marine aerosol (10%). The potential source contribution function (PSCF) and concentration weighted trajectory (CWT) analyses were also used to identify the probable regional source areas of resolved aerosol sources. The main source regions for aerosols in Nainital were the plains in northwest India and Pakistan, polluted cities like Delhi, the Thar Desert, and the Arabian Sea area. The outcomes of the present study are expected to elucidate the atmospheric chemistry, emission source origins, and transport pathways of aerosols over the central Himalayan region.

Flint sources and mobility at the Chalcolithic (3500–2200 BCE) settlement of Zambujal (Portugal)

AbstractProvenance studies of the siliceous sedimentary raw material used by ancient communities are essential to understanding the mobility and exchange networks of these communities. The establishment of the direct procurement territory is the first step to understanding the role of the ‘imported’ artefacts. In this study, flint cores, flakes, bladelets and debitage from the Chalcolithic settlement of Zambujal (Estremadura, Portugal), recovered in excavations between 1964 and 1979, are analysed. We attempt to identify the local and regional source areas of these stone materials and compare their petrography (facies and microfacies textures). This study demonstrates the importance of employing three scales of analysis in petrographic studies (the macro‐, meso‐ and micro‐) to structure and determine flint provenance. Analysis of cortical material shows the relevance of secondary detrital outcrops during the Chalcolithic of the Portuguese Estremadura. Small cobbles were directly collected in both local and regional formations dated to the Palaeogene and Cenomanian, in a large (approx. 40 km) exploration territory, to produce expedient and specialized artefacts (i.e., bladelets). However, a large portion of stone tools from Zambujal made from Cenomanian flint cannot be assigned to local or regional procurement. The unclear provenance of these materials suggests directions for future research.

Ecological and geographical marginality in rear edge populations of Palaearctic forest birds

AbstractAimThe centre–periphery hypothesis predicts that habitat suitability will decrease at the edge of a species’ range, a pattern often questioned by empirical data. Here we explore if habitat suitability decreases southwards and shapes the abundance distribution of rear edge populations of forest birds within the restricted geographical setting of the south‐western Palaearctic. We also test if birds endemic to the area fit more poorly to the latitudinal decrease in habitat suitability due to the putative effect of adaptations to regional conditions.LocationNorth‐western Africa (Morocco).TaxonPasserines (11 species).MethodsBird occurrences were used to model species distribution and line transects were used to estimate bird abundance. Occurrence probabilities provided by species distribution models were used to display the spatial patterning of habitat suitability. Habitat suitability was employed to predict abundance after controlling for the effect of the distance to some regional source areas of forest birds (tree covered large areas). The species were classified as North African endemic according to an updated review of their taxonomic status.ResultsHabitat suitability decreased southwards, supporting the predicted relationship between ecological and geographical marginality in most species. Abundance was positively correlated with habitat suitability and negatively correlated with distance to source areas. The taxonomic status of birds did not affect the patterns.Main conclusionsThe southward decrease in habitat suitability predicted by the centre–periphery hypothesis shapes the distribution of rear edge populations of forest birds within the south‐western Palaearctic. As most of these populations are endemic, the results suggest that they track the gradients in isolation within the geographical setting of north‐western Africa. These results support the vulnerability of these isolated, peripheral populations of forest birds to large‐scale environmental changes in a region under the effect of increasing drought and temperature.

Meteorological characteristics of dust storm events in Turkey

This study investigates dust storm events and their associations with synoptic conditions for the seven geographical regions of Turkey Present weather reports from synoptic codes of 89 meteorology stations and 80 air quality stations from 2014 to 2019 were used to establish the climatological properties of frequent dust storm event days (DEDs) and high dust concentrations over Turkey. To investigate the role of synoptic mechanisms on DEDs, NCEP/NCAR daily mean sea level pressure and 700-hPa height values were used during DEDs for each region. According to the results, Marmara (MR), Aegean (AR), Central Anatolian (CAR), and Black Sea (BSR) regions are influenced by dust storms especially in spring months, and the movement of Sharav cyclones from its source location to Italy and Balkan Peninsula are responsible for transporting high amount of dust particles from the Sahara by strong south and/or southwesterly winds. On the other side, highest daily numbers of dust storms are observed in the Eastern- (EAR) and Southeastern- Anatolian Regions (SEAR) of Turkey during whole year, but mostly in spring and fall months. Differently from the other regional dust source areas, Arabian desert dust is frequently shown in these two regions of Turkey. In SEAR, while surface Cyprus Low and upper level Cyprus trough and associated strong southeasterly winds contribute to have high PM10 concentrations during winter and spring; surface Asiatic monsoon low enables transferring of Arabian dust particles to the region via dry hot air during summer and fall seasons.

珠三角城市群生态空间分区方法与管控对策

生态空间管控是维护区域生态安全，解决区域生态供需矛盾的重要手段。生态空间分区一直是生态管控的热点问题，对促进城市群可持续发展具有重要意义。以珠三角城市群为例，基于政策目标、民众需求、专家知识等方面综合构建评价体系，开展了基于生态空间质量和生态系统健康评价的生态空间分区的探索研究。结果表明：珠三角城市群生态空间约占城市群面积的82.8%，生态空间质量好，但生态系统健康水平低。城市尺度肇庆市、深圳市生态空间质量较高，珠海市、中山市生态空间质量较低；惠州市、肇庆市生态系统健康水平较高，佛山市、中山市生态系统健康水平较低。综合生态空间质量和生态系统健康，区域尺度将城市群生态空间分为重点保护区、重点修复区、潜在修复区和生态保育区。重点保护区占生态空间总面积的10.1%，是区域生态源地，应实行最严格的环境保护制度，划定生态保护红线和自然保护地，加强生态建设和生物多样性保护，并加强生态连通性建设，提升区域整体生态系统服务；重点修复区占生态空间总面积的21.6%，以生态修复，实施生态治理工程，推进生态产业为主；潜在修复区占生态空间总面积的13.1%，以保护优先、自然恢复为主，对生态空间进行全面的养护，保护和提升品质，重点提升生态系统服务；生态保育区占生态空间总面积的55.2%，重点实施生态廊道建设，同时加强区域高标准农田建设，在保护生态空间的基础上合理开展生产建设活动。对生态空间分区管控的研究可方便决策者对生态修复空间和生态保护空间进行识别和分类管理，有效指导国土空间规划和区域生态环境管理体系的完善。;Ecological space management is an important means to maintain regional ecological security and solve the imbalance between regional ecological supply and demand. The classification of ecological space has always been a hot issue in the ecological management and plays an important role in promoting the sustainable development of urban agglomeration. This paper takes the urban agglomeration of Pearl River Delta as an example, based on the policy goals, public preferences, and expert knowledge of urban agglomeration to comprehensively construct the evaluation system. The initial study of the ecological space management zoning was conducted on the basis of the evaluation of the ecological space quality and ecosystem health. The results showed that the ecological space accounted for 82.8% of the area of the urban agglomeration. The quality of the ecological space was good, but the level of the ecosystem health was low. At the urban scale, the ecological space quality of Zhaoqing and Shenzhen was higher, that of Zhuhai and Zhongshan was lower; the ecosystem health of Huizhou and Zhaoqing was higher, that of Foshan and Zhongshan was lower. Integrated with the quality of ecological space and ecosystem health, the ecological space was divided into key protection area, key restoration area, potential restoration area, and ecological conservation area at the regional scale. The key protected areas accounted for 10.1%, which were the regional ecological source areas. The strictest environmental protection system should be implemented, ecological red line and nature protected area should be delimited, strengthen ecological construction and biodiversity protection, also the construction of ecological connectivity should be strengthened to improve the overall regional ecosystem services. The key restoration areas accounted for 21.6%, mainly focusing on ecological restoration, implementation of ecological projects, and promotion of ecological industry. The potential restoration areas account for 13.1%, mainly focusing on protection and natural recovery, comprehensive conservation and protection and improve the quality of ecological space, and focus on improving the function of ecosystem service. The ecological conservation area account for 55.2%, mainly focusing on ecological corridor construction, strengthening the construction of high standard farmland, and protecting the basis of ecological space. Therefore, the production and construction activities should be carried out reasonably. In this paper, the research on the ecological space zoning could facilitate the decision makers to identify and classify the ecological restoration space and the ecological protection space, and could effectively guide the improvement of the land space planning and the regional ecological environment management system.

Source Apportionment of Ambient Black Carbon During the COVID-19 Lockdown.

Black carbon (BC) particles being emitted from mobile and stationary emission sources as a result of combustion activities have significant impacts on human health and climate change. A lot of social activities have been halted during the COVID-19 lockdowns, which has evidently enhanced the ambient and indoor air quality. This paper investigates the possible emission sources and evaluates the meteorological conditions that may affect the dispersion and transport of BC locally and regionally. Ground-level equivalent BC (eBC) measurements were performed between January 2020 and July 2020 at a university campus located in Dammam city of the Kingdom of Saudi Arabia (KSA). The fossil fuel (eBCff) and biomass burning (eBCbb) fractions of total eBC (eBCt) concentrations were estimated as 84% and 16%, respectively, during the entire study period. The mean eBCbb, eBCff, and eBCt concentrations during the lockdown reduced by 14%, 24%, and 23%, respectively. The results of statistical analyses indicated that local fossil fuel burning emissions and atmospheric conditions apparently affected the observed eBC levels. Long-range potential source locations, including Iraq, Kuwait, Iran, distributed zones in the Arabian Gulf, and United Arab Emirates and regional source areas, such as the Arabian Gulf coastline of the KSA, Bahrain, and Qatar, were associated with moderate to high concentrations observed at the receptor site as a result of cluster analysis and concentration-weighted trajectory analysis methods.

Depositional architectures and sedimentation processes in strike-slip extensional basins: Examples from the Oligocene of the Liaodong Bay Sub-basin, Bohai Bay Basin, China

The tectonic histories of continental rift basins tend to be complex, with several episodes of subsidence, extensional and strike-slip tectonic activity and diverse paleogeographic characteristics. Intrabasinal and extrabasinal source areas influence deposition resulting in several sedimentary episodes and depositional architectures. In this study, we use 3D seismic data covering Liaodong Bay and well-logging data to analyze sediment source area, paleo-valleys, and slopes to determine the characteristics, distribution and relationships between the source, transport, and sedimentary systems in the Liaodong Bay Sub-basin, which is an Oligocene strike-slip extensional basin with two regional extrabasinal source areas and a local intrabasinal source area in the basin fill succession. Four types of basin-marginal fluvial paleo-valleys are identified in the Liaodong Bay Sub-basin including incised V-, bifurcate V-, wide V- and shallow V- types. The energy of current decreased successively from incised V-, to bifurcate V-, to wide V-type valleys, which ultimately evolved to become shallow V- type during the late stages of a rift lake basin. These sedimentary systems are grouped into five extrabasinal and two intrabasinal types with diverse depositional architectures, based on their slope shapes. The sedimentation processes of the Liaodong Bay Sub-basin were influenced by the tectonic activity, paleogeomorphology and climate condition during the different stages of the strike-slip extensional basin and controlled the accumulation of sandy sediments.

The reconstruction of burned area and fire severity using charcoal from boreal lake sediments

Although lacustrine sedimentary charcoal has long been used to infer paleofires, their quantitative reconstructions require improvements of the calibration of their links with fire regimes (i.e. occurrence, area, and severity) and the taphonomic processes that affect charcoal particles between the production and the deposition in lake sediments. Charcoal particles &gt;150 µm were monitored yearly from 2011 to 2016 using traps submerged in seven head lakes situated in flat-to-rolling boreal forest landscapes in eastern Canada. The burned area was measured, and the above-ground fire severity was assessed using the differentiated normalized burn ratio (dNBR) index, derived from LANDSAT images, and measurements taken within zones radiating 3, 15, and 30 km from the lakes. In order to evaluate potential lag effects in the charcoal record, fire metrics were assessed for the year of recorded charcoal recording (lag 0) and up to 5 years before charcoal deposition (lag 5). A total of 92 variables were generated and sorted using a Random Forest-based methodology. The most explanatory variables for annual charcoal particle presence, expressed as the median surface area, were selected. Results show that, temporally, sedimentary charcoal accurately recorded fire events without a temporal lag; spatially, fires were recorded up to 30 km from the lakes. Selected variables highlighted the importance of burned area and fire severity in explaining lacustrine charcoal. The charcoal influx was thus driven by fire area and severity during the production process. The dispersion process of particles resulted mostly of wind transportation within the regional (&lt;30 km) source area. Overall, charcoal median surface area represents a reliable proxy for reconstructing past burned areas and fire severities.

Modern pollen source and spatial distribution from surface lake sediments in the southwestern Pampa grasslands, Argentina: Implications to interpret Holocene pollen records

In the Pampa grasslands of Argentina nothing is known about the transport, deposition and spatial distribution of pollen in lakes. To analyze and understand how well lake surface sediment pollen assemblages reflect the contemporary vegetation in relation to pollen source area, bathymetry and grain size sediments 36 surface sediment samples from Chasicó Lake and 5 from its only tributary were analyzed. Lake pollen assemblages showed two major patterns above and below the range between 4 and 6 m depth. Below this range the percentage and concentration of main pollen taxa are relatively homogeneous, without overrepresented taxa and with well-preserved pollen. They reflect the extra-local and regional source areas from Pampa grasslands and xerophylous forest and indicate that pollen from cores taken below this range will be suitable for paleocological studies. Isopoll of the main taxa and grain size distribution maps allowed understand how pollen and sediment was transported, deposited and distributed in the lake. The spatial distributions of main pollen taxa differ considerably among them, generating various pollen assemblages at different sampling points. There is no significant correlation between total pollen concentration and both depth and grain size, suggesting that there are not a totally pollen and sediment focusing in the lake. The pollen distribution indicates that wind and surface runoff are the primary transport vectors to the lake. However, tributary also contributes with the waterborne pollen, particularly around the river mouth. Implications of these processes will be of particular interest for reliable interpretation of fossil pollen records in similar environments.

Differential Probability Functions for Investigating Long-term Changes in Local and Regional Air Pollution Sources

ABSTRACT Conditional probability functions are commonly used for source identification purposes in air pollution studies. CBPF (conditional bivariate probability function) categorizes the probability of high concentrations being observed at a location by wind direction/speed and investigate the directionality of local sources. PSCF (potential source contribution function), a trajectory-ensemble method, identifies the source regions most likely to be associated with high measured concentrations. However, these techniques do not allow the direct identification of areas where changes in emissions have occurred. This study presents an extension of conditional probability methods in which the differences between conditional probability values for temporally different sets of data can be used to explore changes in emissions from source locations. The differential CBPF and differential PSCF were tested using a long-term series of air quality data (12 years; 2005/2016) collected in Rochester, NY. The probability functions were computed for each of 4 periods that represent known changes in emissions. Correlation analyses were also performed on the results to find pollutants undergoing similar changes in local and regional sources. The differential probability functions permitted the identification of major changes in local and regional emission location. In Rochester, changes in local air pollution were related to the shutdown of a large coal power plant (SO2) and to the abatement measures applied to road and off-road traffic (primary pollutants). The concurrent effects of these changes in local emissions were also linked to reduced concentrations of nucleation mode particles. Changes in regional source areas were related to the decreases in secondary inorganic aerosol and organic carbon. The differential probabilities for sulfate, nitrate, and organic aerosol were consistent with differences in the available National Emission Inventory annual emission values. Changes in the source areas of black carbon and PM2.5 mass concentrations were highly correlated.

Armas de guerra ou de caça? Funcionalidade e proveniência das pontas de seta do Zambujal (Torres Vedras, Portugal)

Esta contribuição insere-se num trabalho mais vasto que temos vindo a desenvolver desde 2014 sobre a pedra lascada do Zambujal, focalizado na caracterização petrográfica, nas estratégias de aquisição e na gestão dos recursos siliciosos.&#x0D; O povoado fortificado do Zambujal assume-se como um caso de estudo privilegiado na Estremadura portuguesa, pelo elevado número de artefactos de sílex recuperados associados a um contexto cronoestratigráfico, em particular pela quantidade de pontas de seta proporcionalmente às restantes categorias líticas. Esta questão, juntamente com o facto de terem sido recolhidas naquele local (entre a primeira e a segunda linhas de defesa), reveste-se de grande importância, sugerindo a possibilidade de terem ocorrido conflitos armados entre estas populações ao longo do Calcolítico (3º milénio BCE).&#x0D; Neste estudo propomos testar a hipótese da existência de evidências de guerra no Calcolítico com base numa análise funcional (cálculo do índice de penetração - Ipn) e petrográfica (identificação de microfácies, génese e locais de aprovisionamento das litologias) das pontas de seta recolhidas no interior da barbacã da fortificação.&#x0D; Em conclusão, estes novos resultados, a partir de “velhos” dados, são o ponto de partida para identificar as estratégias de abastecimento e as fases iniciais das cadeias operatórias das pontas de seta do Zambujal, reconhecendo a existência de complexas redes de circulação de bens no Calcolítico que incluem, provavelmente, estratégias de controlo regional e inter-regional, reflectindo relações de estabilidade ou instabilidade entre as comunidades pré-históricas.

What are the contemporary sources of sediment in the Mississippi River?

AbstractWithin the last two centuries, the Mississippi River basin has been transformed by changes in land use practices, dam construction, and training of the rivers for navigation. Here we analyze the contemporary patterns of fluvial sediment yield in the Mississippi River basin using all available data in order to assess the influence of regional land condition on the variation of sediment yield within the basin. We develop regional‐scale relations between specific sediment yield (yield per unit area) and drainage area to reveal contemporary regional sediment yield patterns and source areas of riverine sediments. Extensive upland erosion before the development of soil conservation practices exported large amounts of sediment to the valleys and floodplains. We show that sediment today is sourced primarily along the river valleys from arable land, and from stream bank and channel erosion, with sediment yields from areas dominated by arable land 2 orders of magnitude greater than that of grassland dominated areas. Comparison with the “T factor,” a commonly quoted measure of agricultural soil resilience suggests that the latter may not reflect contemporary soil loss from the landscape.

Determining the contribution of long-range transport, regional and local source areas, to PM10 mass loading in Hessen, Germany using a novel multi-receptor based statistical approach

This study uses two newly developed statistical source apportionment models, MuSAM and MuReSAM, to perform quantitative statistical source apportionment of PM10 at multiple receptor sites in South Hessen. MuSAM uses multi-site back trajectory data to quantify the contribution of long-range transport, while MuReSAM uses wind speed and direction as proxy for regional transport and quantifies the contribution of regional source areas. On average, between 7.8 and 9.1 μg/m3 of PM10 (∼50%) at receptor sites in South Hessen is contributed by long-range transport. The dominant source regions are Eastern, South Eastern, and Southern Europe. 32% of the PM10 at receptor sites in South Hessen is contributed by regional source areas (2.8–9.41 μg/m3). This fraction varies from <20% at remote sites to >40% for urban stations. Sources located within a 2 km radius around the receptor site are responsible for 7%–20% of the total PM10 mass (0.7–4.4 μg/m3). The perturbation study of the traffic flow due to the closing and reopening of the Schiersteiner Brücke revealed that the contribution of the bridge to PM10 mass loadings at two nearby receptor sites increased by approximately 120% after it reopened and became a bottleneck, although in absolute terms, the increase is small.

Late Pleistocene aeolian dust provenances and wind direction changes reconstructed by heavy mineral analysis of the sediments of the Dehner dry maar (Eifel, Germany)

The study presents the results of a heavy mineral analysis from a 38m long record of lacustrine Eifel maar sediments from a core section of the Dehner dry maar. The record encompasses the period from 29,000 to about 12,500 b2k. Statistical analyses enabled the distinction of local and regional source areas of aeolian material and revealed pronounced changes in the amounts of different heavy mineral species and corresponding changes in the grain size Index (GSI and CSI). The results indicate that during the early stages of MIS2 (39 to 30m depth) aeolian sediments were supplied mostly from local sources. This period is characterized by low GSI and CSI ratios resulting from a reduced mobility of material due to a vegetation cover. The period between 23,000 and 12,900 b2k is characterized by a higher supply of heavy minerals from regional and more distant sources. Changes in the provenance areas are indicated in inverse relationships between zircon, rutile, tourmaline (ZRT) and carbonate particles. Shifts in the wind direction are documented in pronounced peaks of carbonate particles indicating easterly winds that have crossed the limestone basins in the Eifeler North South Zone. ZRT-group minerals on the other hand suggest a westerly source area from Palaeozoic clastic sedimentary rocks. The heavy mineral assemblage of the LGM section at 23,000 to 15,000 b2k displays a close correspondence with the stratigraphic relationships that have been obtained for the Landscape Evolution Zone 4 of the ELSA-Vegetation Stack of Sirocko et al. (2016). From the Heinrich 2 event onwards the analyses indicate an increasing degree of mixing of heavy minerals from various provinces. This suggests the existence of a presumably incomplete, thin cover of deflated loess-like sediments that has been repeatedly reworked on the elevated surfaces of the Eifel.

Long-term observations of aerosol size distributions in semi-clean and polluted savannah in South Africa

Abstract. This study presents a total of four years of sub-micron aerosol particle size distribution measurements in the southern African savannah, an environment with few previous observations covering a full seasonal cycle and the size range below 100 nm. During the first 19 months, July 2006–January 2008, the measurements were carried out at Botsalano, a semi-clean location, whereas during the latter part, February 2008–May 2010, the measurements were carried out at Marikana (approximately 150 km east of Botsalano), which is a more polluted location with both pyrometallurgical industries and informal settlements nearby. The median total concentration of aerosol particles was more than four times as high at Marikana than at Botsalano. In the size ranges of 12–840 nm, 50–840 nm and 100–840 nm the median concentrations were 1856, 1278 and 698 particles cm−3 at Botsalano and 7805, 3843 and 1634 particles cm−3 at Marikana, respectively. The diurnal variation of the size distribution for Botsalano arose as a result of frequent regional new particle formation. However, for Marikana the diurnal variation was dominated by the morning and evening household burning in the informal settlements, although regional new particle formation was even more frequent than at Botsalano. The effect of the industrial emissions was not discernible in the size distribution at Marikana although it was clear in the sulphur dioxide diurnal pattern, indicating the emissions to be mostly gaseous. Seasonal variation was strongest in the concentration of particles larger than 100 nm, which was clearly elevated at both locations during the dry season from May to September. In the absence of wet removal during the dry season, the concentration of particles larger than 100 nm had a correlation above 0.7 with CO for both locations, which implies incomplete burning to be an important source of aerosol particles during the dry season. However, the sources of burning differ: at Botsalano the rise in concentration originates from regional wild fires, while at Marikana domestic heating in the informal settlements is the main source. Air mass history analysis for Botsalano identified four regional scale source areas in southern Africa and enabled the differentiation between fresh and aged rural background aerosol originating from the clean sector, i.e., western sector with very few large anthropogenic sources. Comparison to size distributions published for other comparable environments in Northern Hemisphere shows southern African savannah to have a unique combination of sources and meteorological parameters. The observed strong link between combustion and seasonal variation is comparable only to the Amazon basin; however, the lack of long-term observations in the Amazonas does not allow a quantitative comparison. All the data presented in the figures, as well as the time series of monthly mean and median size distributions are included in numeric form as a Supplement to provide a reference point for the aerosol modelling community.

X-ray diffraction and field portable X-ray fluorescence analysis and screening of soils: project design

Abstract This paper presents the preliminary results of a study investigating the application of laboratory X-ray diffraction (XRD) and field portable X-ray fluorescence (XRF) analysis of soils as screening methods for forensic comparison and generalized provenancing. The study area is the Buffalo–Niagara metropolitan region in New York, a glacially draped area of the northeastern USA. For the initial stages of this study, soils are being collected from publicly accessible areas (parks, playgrounds, etc.) for mineralogical and elemental analysis. Initially, minimal sample preparation is being applied to create specimens. An investigation of the published literature reveals that there are a number of different suggested approaches for forensic application of XRD data, not all of which appear to be appropriate to the task at hand. The data being generated in this study are being used to build a reference set for comparison studies. In addition, two simulated forensic samples were collected to test the usefulness of XRD and XRF screening for determining possible regional source areas. For one sample this method was reasonably successful in identifying the general source area, while the results for the second sample were somewhat less satisfactory. In future additional sample handing and analysis protocols will be added.