Peat Sediments Research Articles

Macrofossils analysis of the peat to reconstruct holocene paleoecological conditions about Kansk forest-stepp zone (Yenisey Siberia)

В статье на примере болотного массива «Кускун», расположенного в пойме р.Есауловка (Канская лесостепь) приведены результаты изучения генезиса и эволюции болот северной лесостепи. На основании изучения макрофоссилий торфа, определения зольности и степени разложения, при применении экологических шкал Раменского и Элленберга были реконструированы палеоэкологические условия времени развития болот: дана оценка условий увлажнения за весь период торфонакопления, выделены фазы в развитии болота, описана свойственная им растительность.

The transport of Icelandic volcanic ash: Insights from northern European cryptotephra records

AbstractFine ash produced during volcanic eruptions can be dispersed over a vast area, where it poses a threat to aviation, human health, and infrastructure. We analyze the particle size distributions, geochemistry, and glass shard morphology of 19 distal (>1000 km from source) volcanic ash deposits distributed across northern Europe, many geochemically linked to a specific volcanic eruption. The largest glass shards in the cryptotephra deposits were 250 µm (longest axis basis). For the first time, we examine the replicability and reliability of glass shard size measurements from peatland and lake archives. We identify no consistent trend in the vertical sorting of glass shards by size within lake and peat sediments. Measuring the sizes of 100 shards from the vertical sample of peak shard concentration is generally sufficient to ascertain the median shard size for a cryptotephra deposit. Lakes and peatlands in close proximity contain cryptotephras with significantly different median shard size in four out of five instances. The trend toward a greater amount of larger shards in lakes may have implications for the selection of distal sites to constrain the maximum glass shard size for modeling studies. Although the 95th percentile values for shard size generally indicate a loss of larger shards from deposits at sites farther from the volcano, due to the dynamic nature of the controls on tephra transport even during the course of one eruption there is no simple relationship between median shard size and transport distance.

Clinopyroxene and Fe-Ti oxides for correlating the ash from Changbaishan Millennium eruption

Volcanic glass compositions and tephra layer age are critical for anchoring their sources and correlating among different sites; however, such work may be imprecise when the tephra has varied compositions. The ash from Changbaishan Millennium eruption (940s AD), a widely distributed tephra layer, has been detected in the far-east areas of Russia, the Korean Peninsula, Japan, and in Greenland ice cores. There are some debates on the presence of this tephra from sedimentary archives to the west of Changbaishan volcano, such as lake and peat sediments in the Longgang volcanic field. In this paper, major element compositions for clinopyroxene and Fe-Ti oxides were performed on proximal tephra from Changbaishan and the Millennium eruption ash record in Lake Sihailongwan. Clinopyroxene and Fe-Ti oxides microlites from Sihailongwan show augite- ferroaugite and titanmagnetite compositions, similar to those from dark pumice in Changbaishan proximal tephra, but different from the light grey pumice, which has ferrohedenbergite and ilmenite microlite compositions. This result implies that the tephra recorded in Sihailongwan was mainly from the trachytic eruptive phase of the Millennium eruption, and the rhyolitic eruptive phase made a relatively small contribution to this area. Analyzing clinopyroxene and Fe-Ti oxides microlites is a new method for correlating tephra layers from Changbaishan Millennium eruption.

Detection of the Askja AD 1875 cryptotephra in Latvia, Eastern Europe

ABSTRACTWe report the first geochemically confirmed findings of the Askja volcano (Iceland) AD 1875 eruption cryptotephra in Eastern Europe. The cryptotephra finding in Latvia is the easternmost finding of the Askja AD 1875 so far, providing an important time marker in the sediments. Although low concentrations of Askja AD 1875 rhyolitic glass shards were recorded, our findings suggest the possibility of also tracing other historical cryptotephras in lacustrine and peat sediments in Eastern Europe. We use the Askja AD 1875 tephra isochrone to synchronize pollen data of human activities, i.e. rye (Secale cereale) cultivation. Our comparison of Secale pollen from two sites reveals that there were minor dissimilarities in the timing of highest rye cultivation, and that a synchronous decrease of rye cultivation occurred at both sites few years after the Askja eruption at AD 1875.

Late Quaternary vegetation development and disturbance dynamics from a peatland on Mount Gorongosa, central Mozambique

Few long-term climate and environmental records are available for southeast Africa where millennial scale shifts in the north-south position of the Intertropical Convergence Zone (ITCZ) and changes in Indian Ocean sea surface temperatures interact with local controls (e.g., fire, hydrology) to influence vegetation and ecosystem dynamics. Reconstruction of late-Pleistocene – Holocene environmental change from peat sediments obtained from Mount Gorongosa, central Mozambique, provides insight into vegetation, climate and disturbance interactions over the past c. 27 kyr. During the late Pleistocene, cool and wet climatic conditions supported Podocarpus forest and Ericaceae-heathland until drier conditions led to grassland expansion and a hiatus in peat deposition between c. 22.5 and 7.2 cal kBP. Increased temperatures and fire activity since c. 7.2 cal kBP led to further expansion of grasslands. Continued warming helped maintain grasslands and fostered a diverse mix of Podocarpus forest with a large number of subtropical trees and miombo woodland taxa (especially Brachystegia spp.) until regional land-use associated with the rise of Iron Age activity promoted an increase of disturbance related taxa over the last 1–2 millennia. Recent migration of people onto the Mount Gorongosa massif in the last fifty years are linked to an increase in fire activity that is unprecedented in the 27 kyr record, resulting in shifts in vegetation composition and structure. This long-term record of environmental change from central Mozambique highlights complex interaction between overlapping climatic influences and documents important vegetation transitions linked to millennial scale climatic controls, disturbance processes and more recent land-use change from a region where few records exist.

Investigation of peat sediments from Daiyun Mountain in southeast China: late Holocene vegetation, climate and human impact

In this study, late Holocene vegetation, climate and human impacts were investigated using multiproxy data-pollen percentages, pollen accumulation rates (PAR), humification and loss-on-ignition (LOI)—measured from peat sediments from Daiyun Mountain, southeast China. A stratigraphic chronology was established on the basis of four radiocarbon dates. The 4,350 year sequence of vegetation history and climate change exhibits three distinctive stages: (1) 4,350–1,000 cal bp, during which the vegetation was dominated by evergreen forests mainly composed of broad-leaf trees, indicating a warm and wet climate; (2) 1,000–550 cal bp, during which the climate was thought to be cool and dry, based on a decrease in pollen percentages and the PARs of trees, shrubs and wetland herbs, and an increase in the pollen percentage and PAR of dry land herbs, as well as high overall LOI values; and (3) 550 cal bp to modern times, during which higher pollen percentages of dry land and wetland herbs, along with low pollen percentage and PAR of trees and shrubs, as well as low absorbance and LOI values, suggest relatively cooler but wetter climate conditions. In addition, major climatic events, such as the warm period from ad 670–960, the Medieval Warm Period (ad 1050–1520) and the Little Ice Age (ad 1580–1850), could be identified within the peat sediments in this study, with climatic conditions at these times being characteristically warm and wet, warm and dry, and cold and wet, respectively. Pollen signals indicate significant human impact since 1,000 cal bp, which may be linked to the development of the local porcelain industry and a rapid increase in the population in the study region.

Subfossil bog-pine chronologies from The Puścizna Wielka raised bog, Orawa Basin, southern Poland

Subfossil wood of the Scots pine (Pinus sylvestris L.) appearing in the peat sediments in southern Poland presents material for the construction of long tree-ring chronologies that are of potential utility in palaeoclimatic reconstructions. Over 600 subfossil pine samples, in form of discs, were taken for dendrochronological analyses from the Puścizna Wielka peat bog, the only economically exploited bog in the Carpathians. Based on these samples, five floating chronologies covering ca. 1700 years were constructed. They were dated with the wiggle-matching technique to the years: 3485–3295 (±25), 3205–2575 (±25), 2445–2200 (±50), 2210–1990 (±40), 1100–610 (±10) cal BC. These results indicate that the trees grew on the valley bog during the initial phase of its development. The vast majority of the trees analysed grew on the peat bog between ca. 3500 and ca. 2000 cal BC, with breaks in the record dated to ca. 3290–3200 cal BC, ca. 2570–2450 cal BC. Pines invaded the peat bog in drier periods, whereas a high groundwater level, presumably related to increased precipitation, was a factor determining mortality of the trees. This study therefore fills a geographical gap in the coverage by subfossil pine records as there are no studies on subfossil pine trees from peat bogs in Central-Eastern Europe.

Paleoenvironmental analysis from the main phytoliths morphotypes found in peat sediment in Guarapuava region-Paraná

É crescente a preocupação dos cientistas em relação aos eventos ambientais que vigoraram no passado, a fim de buscar um entendimento maior sobre processos e configurações atuais. Assim, os estudos sobre o Quaternário têm, na sua essência, a preocupação do passado com o presente, utilizando diversas técnicas e materiais. Este trabalho apresenta os resultados obtidos por meio da análise dos principais tipos de fitólitos encontrados em depósito turfoso, localizado no reverso da escarpa da Esperança, no município de Guarapuava, Paraná, em associação com duas datações 14 C. Os resultados obtidos informaram que o depósito estudado é datado do Período Pleistoceno, sendo que sua idade é de 15.648 anos AP (A partir do Presente). Foi possível, também, traçar três fases paleoambientais. Na fase I, a baixa concentração fitolítica e a presença de fitólitos típicos de palmeiras, sugerem que a área estudada, com datação de 15.648 anos AP, foi dominada por vegetação do tipo floresta. Em segundo momento, na fase II, ocorre, inicialmente, um significativo incremento de fitólitos no depósito. É sugestivo que tenha ocorrido uma leve abertura na vegetação, deduzida pela participação de Chloridoideae e significativa presença de Panicoideae. A vegetação foi marcada por um misto de floresta e campo. Quanto à fase III, acredita-se que as características climáticas tenham sido muito próximas às atuais. Em relação à flora, uma tendência de associação mista se manteve, porém com maior frequência de morfotipos de fitólitos relacionados à vegetação de floresta, como Bilobates e Globulars. Esses resultados, por apontar a presença de vegetação do tipo floresta, há 15.648 anos AP, sugere que a região estudada possa ter sido, no passado, um refúgio florestal. Abstract There is a growing concern among scientists in relation to environmental events that were effective in the past in order to seek a better understanding of processes and current settings. Thus, studies on the Quaternary have in essence the concern of the past with the present, using various techniques and materials. This paper presents the results obtained by the analysis of the main types of phytoliths found in a peat deposit located on the reverse of the rugged Esperança in Guarapuava – Paraná state, in association with two 14 C datings. The results indicated that the studied deposit is dated to the Pleistocene, and its age is 15.648 years (as of the present). It was also possible to draw three paleoenvironmental phases. In phase I, the low concentration of phytoliths and the presence of typical palm phytoliths suggest that the studied area dated around 15.648 years BP was dominated by forest. In phase II there was initially a significant increase in phytoliths along the deposit. It is suggestive that there has been a slight opening in the vegetation due to the occurrence of Chloridoideae and a significant presence of Panicoideae. The vegetation was marked by a mix of forest and fields. As for phase III, it is believed that the climatic characteristics were very close to those now existing. Regarding the flora, a tendency of mixed vegetation remained, but with a higher frequency of morphotypes of phytoliths related to forest vegetation, as Bilobates and Globular. These results point to the presence of the forest vegetation for 15.648 years (as of the present). It is indicative that the studied area may have been a forest retreat.

Holocene Vegetation Succession and Response to Climate Change on the South Bank of the Heilongjiang-Amur River, Mohe County, Northeast China

Pollen samples from peat sediments on the south bank of the Heilongjiang River in northern Northeast China (NE China) were analyzed to reconstruct the historical response of vegetation to climate change since 7800 cal yr BP. Vegetation was found to have experienced five successions from cold-temperate mixed coniferous and broadleaved forest to forest-steppe, steppe-woodland, steppe, and finally meadow-woodland. From 7800 to 7300 cal yr BP, the study area was warmer than present, andBetula, Larix, andPicea-dominated mixed coniferous and broadleaved forests thrived. Two cooling events at 7300 cal yr BP and 4500 cal yr BP led to a decrease inBetulaand other broadleaved forests, whereas herbs of Poaceae expanded, leading to forest-steppe and then steppe-woodland environments. After 2500 cal yr BP, reduced temperatures and a decrease in evaporation rates are likely to have resulted in permafrost expansion and surface ponding, with meadow and isolated coniferous forests developing a resistance to the cold-wet environment. The Holocene warm period in NE China (7800–7300 cal yr BP) could have resulted in a strengthening of precipitation in northernmost NE China and encouraged the development of broadleaved forests.

ISOLATION OF BACTERIA FROM THE ACIDIC PEAT SWAMP FOREST SOIL AND THEIR LIGNIN DEGRADATION POTENTIAL

The tropical peat swamp forest in Malaysia has reduced significantly due to increasing pressure for development and demand for agricultural land. Pekan peat swamp forest is part of the 200,000 hectares of peat swamp forest located in Pahang, Peninsular Malaysia. While more extensive studies were done on flora and fauna, the study on microbial diversity in this habitat is very limited. The highly acidic environment, low concentrations of nutrients and anoxic condition of the peat are among challenges that hampered the cultivation of microorganism from this environment. In this study two types of agar-based medium, M1 minimal medium (M1) and peat water medium (PW) supplemented with glucose, methanol and lignin were used to isolate bacteria from the peat sediment. In comparison to M1, the use of PW has resulted with higher number of isolates with different morphologies. The PW mainly contains the acidic peat water that was collected from the sampling location. Based on the growth on medium supplemented with lignin, selected isolates were identified using 16s rDNA sequencing. At least three of the isolates showed sequence similarity to Burkholderia sp., which is one of the common species, studied on their ligninase-producing abilities. The results from this study serve as the preliminary data for further work on growth characteristics and enzymatic potential of isolates from acidic peat swamp soil.

A comparative study of long-term Hg and Pb sediment archives

Environmental contextLead and mercury are toxic atmospheric pollutants emitted in large quantities since 1850. Accumulating lake and peat sediments capture the pollutants from the atmosphere and indirectly record changes in deposition through time. This study of four long-term sediment records addresses the questions, ‘What proportion of this atmospheric deposition is natural background?’ and ‘Does the archive faithfully represent true rates of atmospheric deposition?’ AbstractAtmospheric phenomena have a large influence on the flux of mercury (Hg) and lead (Pb) to terrestrial and aquatic ecosystems. Some direct phenomena involve high-frequency variations in air movement; other indirect processes involve longer-term changes in climate and associated vegetation and hydrology. Here, we use evidence from sediment cores to explore how these atmospheric and landscape processes produced large natural variations in Hg and Pb deposition over thousands of years before industrial pollution. Cores from Sargent Mountain Pond, coastal Maine, USA (16600 years), Plešné Lake, south-western Czech Republic (15000 years), Lake Tulane, central Florida, USA (45000 years), and Caribou Bog, Orono, Maine, USA (10000 years) each illustrate how long-term local environmental changes influence the deposition and net retention of Hg and Pb. Important natural factors that emerge from comparisons among these four sites include forestation, changing groundwater hydrology, evolution of the watershed and lake system and (watershed area)/(lake area) ratio, all overlain by late-Holocene anthropogenic atmospheric pollution.

8000 years of environmental evolution of barrier–lagoon systems emplaced in coastal embayments (NW Iberia)

The rocky and indented coast of NW Iberia is characterized by the presence of highly valuable and vulnerable, small and shallow barrier–lagoon systems structurally controlled. The case study was selected to analyse barrier–lagoon evolution based on detailed sedimentary architecture, chronology, geochemical and biological proxies. The main objective is to test the hypothesis of structural control and the significance at regional scale of any high-energy event recorded. This work is also aimed at identifying general patterns and conceptualizing the formation and evolution of this type of coastal systems. The results allowed us to establish a conceptual model of Holocene evolution that applies to rock-bounded barrier–lagoon systems. The initial stage (early Holocene) is characterized by freshwater peat sedimentation and ended by marine flooding. The timing of the marine flooding depends on the relation between the elevation of the basin and the relative mean sea-level position; the lower the topography, the earlier the marine inundation. Thus, the age of basin inundation ranged from 8 to 4 ka BP supporting significant structural differences. Once marine inundation occurred, all systems followed similar evolutionary patterns characterized by a phase of landward barrier migration and aeolian sedimentation towards the back-barrier (i.e. retrogradation) that extended circa 3.5 ka BP. The later phases of evolution are characterized by a general trend to the stabilization of the barriers and the infilling of the lagoons. This stabilization may be temporally interrupted by episodes of enhanced storminess or sediment scarcity. In this regard, washover deposits identified within the sedimentary architecture of the case study explored here suggest pervasive high-energy events coeval with some of the cooling events identified in the North Atlantic during the mid- to late Holocene.

Effects of redox conditions on the control of arsenic mobility in shallow alluvial aquifers on the Venetian Plain (Italy)

The Venetian Plain is known for the occurrence of areas with high concentrations of arsenic in groundwater (greater than 400μg/L). The study area represents the typical residential, industrial and agricultural features of most Western countries and is devoid of hydrothermal, volcanic or anthropogenic sources of arsenic. The aim of the study is to model the arsenic mobilization and the water–rock interaction by a complete hydrogeochemical investigation (analyses of filtered and unfiltered groundwater sediment mineralogy and geochemistry). The groundwater arsenic contamination and redox conditions are highly variable. Groundwaters with oxidizing and strongly reducing potentials have much lower arsenic concentrations than do mildly reducing waters. The grain size of the aquifer sediments includes gravels, sands and silty-clays. A continuous range of organic material concentrations is observed (from zero to 40%). The amount of sedimentary organic matter is highly correlated with the arsenic content of the sediments (up to 300mg/kg), whereas no relationships are detectable between arsenic and other chemical parameters.The occurrence of arsenic minerals was observed as a peculiar feature under the scanning electron microscope. Arsenic and sulfur are the sole constituents of small tufts or thin crystals concentrated in small masses. These arsenic minerals were clearly observed in the peat sediments, in agreement with the geochemical modeling that requires very reducing conditions for their precipitation from the groundwater. The modeling suggests that, under oxidizing conditions, arsenic is adsorbed; moreover, a continuous decrease in the redox potential causes increasing desorption of arsenic. If the reducing conditions become more intense, the formation of As-S minerals would explain the lower concentration of arsenic measured in the strongly reducing groundwater. Even if As-sulfides are rare under low-temperature conditions, the anomalous abundance of reductants (organic matter) can locally stabilize As-S minerals, which can scavenge large quantities of groundwater arsenic.

A combined biogeochemical and palaeobotanical approach to study permafrost environments and past dynamics

When investigating past peatland processes and related carbon cycle dynamics, it is essential to identify and separate different peat environments: bogs, fens and permafrost, and their historical plant assemblages. Bog peat layers contain relatively well-preserved plant material for palaeoecological examination, whereas fen and permafrost peats are often highly humified, which in turn constrains reconstructions of past plant assemblages. Here, we analysed the chemical composition of arctic peat plateau plants to create a local reference training-set of plant biomarkers. We then combined palaeobotanical, biogeochemical and chronological analyses to one permafrost peat sequence collected from the East European Russian tundra (67°03′N, 62°57′E) to investigate past peatland dynamics and to evaluate the performance of the biomarker method in a highly decomposed permafrost environment. The results show that the chronologically constrained macrofossil analysis provided most of the essential information about the peatland succession. However, a more robust reconstruction of the past peatland dynamics was achieved by combining palaeobotanical and biogeochemical data sets. The similarity of the lipid biomarker distributions of the arctic and boreal peatland plants also implies that any established modern biomarker training-set of peatland plants could be applied universally to palaeoecological studies on peat sediments.

Proxy comparison in ancient peat sediments: pollen, macrofossil and plant DNA.

We compared DNA, pollen and macrofossil data obtained from Weichselian interstadial (age more than 40 kyr) and Holocene (maximum age 8400 cal yr BP) peat sediments from northern Europe and used them to reconstruct contemporary floristic compositions at two sites. The majority of the samples provided plant DNA sequences of good quality with success amplification rates depending on age. DNA and sequencing analysis provided five plant taxa from the older site and nine taxa from the younger site, corresponding to 7% and 15% of the total number of taxa identified by the three proxies together. At both sites, pollen analysis detected the largest (54) and DNA the lowest (10) number of taxa, but five of the DNA taxa were not detected by pollen and macrofossils. The finding of a larger overlap between DNA and pollen than between DNA and macrofossils proxies seems to go against our previous suggestion based on lacustrine sediments that DNA originates principally from plant tissues and less from pollen. At both sites, we also detected Quercus spp. DNA, but few pollen grains were found in the record, and these are normally interpreted as long-distance dispersal. We confirm that in palaeoecological investigations, sedimentary DNA analysis is less comprehensive than classical morphological analysis, but is a complementary and important tool to obtain a more complete picture of past flora.

Millennial-Scale Asian Monsoon Influenced Longjie Lake Evolution during Marine Isotope Stage 3, Upper Stream of Changjiang (Yangtze) River, China

Millennial-scale climate change in Asian monsoon region during MIS 3 has been studied using stalagmite, loess, and peat sediments. However, records from more materials are essential to further illustrate dynamics of these events. In the present study, a time-series of grain size covering 60–30 ka was reconstructed from lake sediments in the Yunnan Province, southwestern China. The time-series contains 14 obvious millennial-scale events during the period. On millennial-scale, the grain size record is generally consistent with mean stalagmiteδ18O from Hulu Cave, grain size of Gulang loess sequence, Chinese Loess Plateau, and Greenland ice coreδ18O. The results show that the millennial-scale variation was well compared with the Dansgaard-Oeschger (DO) events, indicating that those global events were well documented in lake sediments in the Asian monsoon region. Because the grain size can be used as a proxy for water discharge, we suggest that signal of the DO events might be transmitted to lake evolution by Asian monsoon.

Biosorption of Metallic Elements onto Fen Peat

Abstract Industrial development and anthropogenic activity have a huge impact on the environment, forcing society to find new and cost-effective environment treatment technologies. One of the most effective and environmentally friendly methods is the use of biosorbents, for which peat is one of the most cost-effective materials. The adsorption capabilities of peat sediments are well known; however, mainly raised bog peat is used for environmental treatment, and thus the abilities of fen peat are underestimated. The aim of this research was to assess the fen peat suitability as an adsorbent for metallic elements. In this study we have determined the sorption characteristics of Ca, Mg, K, Na, Cu and Pb and results show that fen peat deposits have a huge variability as a biosorbent due to their variable botanical composition and complex properties, for instance, under equal conditions, wood-sedge peat can have higher lead adsorption capacity than wood peat. However, due to its natural content of metallic elements, the sorption capacity overall is lower than it is for raised bog peat, although the high pH reaction encourage a high mobility metals.

Alpine treeline and timberline dynamics during the Holocene in the Northern Romanian Carpathians

High altitude environments (treeline and alpine communities) are particularly sensitive to climate changes, disturbances and land-use changes due to their limited tolerance and adaptability range, habitat fragmentation and habitat restriction. The current and future climate warming is anticipated to shift the tree- and timberlines upwards thus affecting alpine plant communities and causing land-cover change and fragmentation of alpine habitats. An upslope movement of some trees, shrubs and cold adapted alpine herbs as a response to the current climate warming has already been noted in many montane and subalpine regions. Four Holocene peat and lacustrine sediment sequences located between 1670 and 1918 m a.s.l. (Fig.1), in the Rodna Mountains (Northern Romania, Eastern Carpathians) are used with the aim to determine: i) the sensitivity of high mountain habitats to climate, fire and land use changes; ii) tree- and timberline shifts: and iii) the influence of landscape topography on trees and shrubs.

Holocene variations in peatland methane cycling associated with the Asian summer monsoon system.

Atmospheric methane concentrations decreased during the early to middle Holocene; however, the governing mechanisms remain controversial. Although it has been suggested that the mid-Holocene minimum methane emissions are associated with hydrological change, direct evidence is lacking. Here we report a new independent approach, linking hydrological change in peat sediments from the Tibetan Plateau to changes in archaeal diether concentrations and diploptene δ13C values as tracers for methanogenesis and methanotrophy, respectively. A minimum in inferred methanogenesis occurred during the mid-Holocene, which, locally, corresponds with the driest conditions of the Holocene, reflecting a minimum in Asian monsoon precipitation. The close coupling between precipitation and methanogenesis is validated by climate simulations, which also suggest a regionally widespread impact. Importantly, the minimum in methanogenesis is associated with a maximum in methanotrophy. Therefore, methane emissions in the Tibetan Plateau region were apparently lower during the mid-Holocene and partially controlled by interactions of large-scale atmospheric circulation.

Evolução Paleogeográfica da Planície Costeira da Praia Vermelha, Entrada da Baía de Guanabara, Rio de Janeiro, por meio de Registros Palinológicos

Peat sediments were observed during high tide occasions in the Praia Vermelha beach, urban area of the Rio de Janeiro city. They were studied to investigate possible environmental variations during the Quaternary Period. Palynological analysis was carried out comprising a time interval from ca. 4.520 À 80 to 4.270 À 60 years B.P. During this time the results obtained indicate that a restinga forest vegetation was sequentially dominated by a restinga bog vegetation. A great number of spores presenting corrosion/degradation damage, typical characteristics of exposition to the air, indicate that low quantity of water was disposable occasionally.