A 1,100-year palaeoenvironmental record inferred from stable isotope and trace element compositions of ostracode and plant caryopses in sediments of Cattle Pond,Dongdao Island,South China Sea

Abundant ostracode valves (Cyprinotus cingalensis) and caryopses of Urochloa paspaloides, a terrestrial grass, were well preserved in the lacustrine sediments of the Cattle Pond on Dongdao Island, South China Sea. Oxygen and carbon isotopes, and elements (Ca, Mg) were analyzed on ostracode valves and plant caryopses in this study. The δ¹⁸O_ostracode and δ¹³C_ostracode exhibited a positive and statistically significant correlation, and showed a decreasing trend toward the top of sediment sequence with some fluctuations, indicating a gradual increase in effective moisture. The Mg/Ca ratios in the ostracode shells, generally used as a proxy for salinity changes in lake water, showed a trend toward lower values in the upper samples, reflecting a gradual decrease of salinity in the lake. The δ¹³C_org values in the plant caryopses of the upper 14 cm of sediment have lower values than those in the bottom sediments, suggesting less water and salinity stress. These results indicate increasing effective moisture and rainfall intensity over the past ∼1,100 years on Dongdao Island.     

A 42-yr soil erosion record inferred from mineral magnetism of reservoir sediments in a small carbonate-rock catchment,Guizhou Plateau,southwest China

Shibanqiao Reservoir (25°56′56.5′′ N, 105°26′44.5′′ E and ∼1400 m a.s.l.), southwest Guizhou Plateau, SW China, was built in 1958. It lies in an area of sub-tropical monsoon humid climate in a carbonate-rock-dominated catchment of 6 km². Two sediment cores (24 and 23 cm long) were retrieved from the reservoir, and four soil profiles were sampled in the catchment. Mineral magnetism was measured on all sediment and soil samples. Soil and sediment magnetic measurements together with analyses of sediment ¹³⁷Cs activity, particle-size, TOC, and C/N revealed changes in soil erosion between 1960 and 2002. During some phases, erosion (probably as splashing and/or sheeting) was relatively low and tended to take place only in the topsoil as indicated by high ARM/SIRM of the sediments. During other phases, erosion (probably as rilling and/or initial gullying) was relatively intense and thus disturbed the deeper soils, as expressed by high IRM_−100mT/SIRM. Most of the changes in relative intensity of erosion can be ascribed to fluctuations in precipitation. Changes in land use/land cover or human activities may account, in part, for changes in soil erosion inferred for four more roughly identified periods.     

Sedimentary pellets as an ice-cover proxy in a High Arctic ice-covered lake

Sediment aggregates (“sedimentary pellets”) within the sedimentary record of Lake A (83°00′ N, 75°30′ W), Ellesmere Island, Canada, are used to construct a 1000 year proxy record of ice-cover extent and dynamics on this perennially ice-covered, High Arctic lake. These pellets are interpreted to form during fall or early winter when littoral sediment adheres to ice forming around the lake’s periphery or during summer through the development of anchor ice. The sediment likely collects in ice interstices and is concentrated in the upper ice layers through summer surface ice melt and winter basal ice growth. The pellets remain frozen in the ice until a summer or series of summers with reduced ice cover allows for their deposition across the lake basin. Sedimentary pellet frequency within multiple sediment cores is used to develop a chronology of ice-cover fluctuations. This proxy ice-cover record is largely corroborated by a record of unusual sedimentation in Lake A involving iron-rich, dark-orange to red laminae overlying more diffuse laminae with a lighter hue. This sediment sequence is hypothesized to represent years with reduced ice cover through increased chemocline ventilation and iron deposition. During the past millennium, the most notable period of inferred reduced ice cover is ca. 1891 AD to present. Another period of ice cover mobility is suggested ca. 1582–1774 AD, while persistent ice cover is inferred during the 1800s and prior to 1582 AD. The proxy ice-cover record corresponds well with most regional melt-season proxy temperature and paleoecological records, especially during the 1800s and 1900s.

Late Holocene Adélie penguin population dynamics at Zolotov Island,Vestfold Hills,Antarctica

We inferred late Holocene Adélie penguin occupation history and population dynamics on Zolotov Island, Vestfold Hills, Antarctica, using geochemical data from a dated ornithogenic sediment core (ZOL4). Radiocarbon dates on fossil penguin bones in the core indicate that Adélie penguins occupied the island as early as 1,800 years before present (yr BP), following the retreat of the Sørsdal glacier. This occupation began ~1,200 years later than that observed at Ardley Island and King George Island, in the South Shetland Islands. Phosphorus was identified as the most indicative bio-element for penguin guano in core ZOL4, and was used to infer past penguin population dynamics. Around 1,800 years ago, the Adélie penguin populations at both Zolotov Island and Ardley Island increased rapidly and reached their highest levels ~1,000 yr BP. For the past ~900 years, the penguin populations at Zolotov Island have shown a general rising trend, with fluctuations, while those at Ardley Island have shown a moderate decreasing trend. The Adélie penguin populations at both Ardley Island and Zolotov Island showed a clear decline ~300 years ago, which we interpret as a response to the Little Ice Age, or a neoglacial cooling event.     

Reflectance spectroscopy: a new approach for reconstructing penguin population size from Antarctic ornithogenic sediments

Reflectance spectroscopy has several advantages compared to traditional chemical methods in paleolimnology. It requires little cost, involves minimal or no sample preparation and is rapid. There has, however, been limited use of reflectance spectroscopy in polar paleolimnological studies. This paper explores the application of reflectance spectroscopy to reconstruct historical changes in penguin population size in the maritime Antarctic. Two ornithogenic sediment cores on Ardley Island, Antarctica were analyzed. Penguin droppings and weathered soils were analyzed as reference materials. Principal component analysis and linear mixing modeling were performed on the spectral data to estimate the proportion of penguin guano in the sediments and these values were used to infer historical penguin population numbers. Historical penguin population size versus time, reconstructed from reflectance spectra, and population numbers inferred from previous geochemical analysis of bio-elements, were quite similar. Our results illustrate the feasibility of rapidly inferring historical changes in penguin population size using reflectance spectroscopy on Antarctic ornithogenic sediments. Our findings suggest that this technique has potential for reconstructing past population numbers of other seabirds and mammals using lake sediments influenced by animal excrement.     

A 2000-year record of copper pollution in South China Sea derived from seabird excrements: a potential indicator for copper production and civilization of China

In the Chinese feudal era, copper was widely used in coinage and weapons, and its production was coupled with political stability and economic prosperity. In the smelting process, copper was released into the environment and accumulated in the food web, and it became enriched in animal tissues and in seabird droppings. Here we report a 2000-year record of copper in red-footed booby excrement from Dongdao Island, South China Sea. There exists a striking correlation between the copper content in the seabird excrements and the ancient copper production of China for past two millennia. The increased Cu content corresponds to the flourishing times of dynasties, such as the Tang and Sung Dynasties, and declines in Cu content correspond with dynastic declines. Even some brief (decadal) wars and calamities, such as the Anshi Rebellion in AD 755–763 and the Taiping Heavenly Kingdom in AD 1851–1864, were recorded in the copper content profile. We established an approximate function to model the quantitative relationship between the copper content in the seabird excrement and the ancient copper production. We estimate that a total of ~14 million tons of copper was produced during the past two millennia in China. Among the 14 million tons of copper, about 0.65 million tons was released into the atmosphere.     

Recent Summer Climate Recorded in Complex Varved Sediments, Nicolay Lake, Cornwall Island, Nunavut, Canada

The recent (1950–1996) varve record from the proximal sediments in Nicolay Lake, Cornwall Island, Nunavut, Canada (77°46′ N, 94°40′ W) contains distinct subannual rhythmites. Deposition of these subannual rhythmites is due primarily to nival snow melt, with additional sedimentary units resulting from major summer precipitation and subaqueous mass wasting events. In order to evaluate the potential hydroclimatic signal contained in the varves from the unglacierized catchment, the nival deposition record was estimated by delineating the initial subannual rhythmite within each varve. When the record is split into temporal segments based on two phases that exhibit different sediment deposition patterns in the lake, the nival rhythmites are significantly correlated to annual cumulative melting degree days (MDD) from the nearest weather station Isachsen (78°47′ N, 103°32′ W) (1950–1962 AD and 1963–1977 AD with r = 0.55 and r = 0.82, respectively). A similar analysis with data from Resolute (74°43′ N, 94°59′ W) yields slightly weaker correlations (1950–1962 AD, r = 0.60; 1963–1994, r = 0.59). The strong positive correlation with both the Isachsen and Resolute thermal records suggests that the paleoclimatic signal in the sediments reflects regional climate conditions. Notably, the signal is strongest when the entire melt season is considered; weaker correlations with instrumental weather records are associated with comparisons limited to the peak melt or early season melt periods. We attribute this to the ongoing supply of snowmelt through the season in this polar region and the availability of sediment for transport throughout the melt season. These results indicate that a high resolution hydroclimatic signal is present in the sediments from Nicolay Lake and can be used for paleoclimate reconstruction provided sedimentary depositional controls are taken into account.     

反射光谱技术:研究南极企鹅古生态演化的一种新方法

为探求快速、廉价、无损和同步的光谱技术在南极生态环境研究中的可能性,本文利用南极阿德雷岛的四根企鹅粪土沉积柱样品的反射光谱,通过逐步多元线性回归和主成分回归两种数学运算方法,建立了反射光谱数据与企鹅粪九种标型元素浓度之间的关系,并探讨了南极企鹅粪土沉积物光谱数据的古生态意义。结果表明:南极粪土沉积样品反射率光谱与企鹅粪九种标型元素(P、Ca、Cu、F、Ba、S、Zn、Sr、Se)含量之间存在良好的相关性,预测值与实测值之间的相关系数R都达到了0.9以上,在深度剖面上预测浓度与实测浓度具有非常一致的变化趋势;南极粪土沉积物光谱数据包含有明确的古生态变化信息,可利用主成分分析快速恢复历史时期企鹅数量演化过程。本研究结果为在偏远的南极地区开展古生态环境研究提供了一种新的快捷方法和技术途径。     

Diatoms reveal complex spatial and temporal patterns of recent limnological change in West Greenland

Diatoms in sediment cores were analysed across a range of stratigraphic resolutions along a transect of 23 lakes spanning the ice-free margin of the west coast of Greenland (~67°N), to explore spatial and temporal patterns of recent (last ~150 years) environmental change in the region. These records display heterogeneous lake development trajectories over the last several centuries. Estimates of species composition turnover (beta-diversity) since 1850 AD are among the lowest for lakes in the Arctic, and are comparable to “unimpacted” reference lakes from temperate regions. Most of the change that occurred in West Greenland lakes pre-dates potential industrial anthropogenic effects, while post-1850 change is well within the natural range of variability for these systems. Nonetheless, a spatial pattern in core “top–bottom” changes is apparent across the transect: lakes in the arid interior of the region, adjacent to the ice sheet, and those with higher pH, register greater change than those in the more maritime climate of the coast. This suggests that climate plays an indirect role in the recent development of these lakes, and that recent anthropogenic forcing has not yet exceeded major ecological thresholds in this region.     

Anthropogenic radionuclides in the water column and a sediment core from the Alboran Sea: application to radiometric dating and reconstruction of historical water column radionuclide concentrations

Global fallout is the main source of anthropogenic radionuclides in the Mediterranean Sea. This work presents ¹³⁷Cs, ^239+240Pu and ²⁴¹Am concentrations in the water column in the southwest Alboran Sea, which was sampled in December 1999. A sediment core was taken at 800 m depth in the area (35°47′ N, 04°48′ W). ²¹⁰Pb, ²²⁶Ra, ¹³⁷Cs and ^239+240Pu specific activities were measured at multiple depths in the core for dating purposes. ¹³⁷Cs and ^239+240Pu profiles did not show defined peaks that could be used as time markers, and they extended up to depths for which the ²¹⁰Pb-based constant rate of supply (CRS) dating model provided inconsistent dates. These profiles can be useful to test dating models, understood as particular solutions of a general advection–diffusion problem, if the time series of radionuclide inputs into the sediment is provided. Thus, historical records of depth-averaged ¹³⁷Cs and ^239+240Pu concentrations in water, and their corresponding fluxes into the sediment, were reconstructed. A simple water-column model was used for this purpose, involving atmospheric fallout, measured distribution coefficient (k _d) values, and a first-estimate of sedimentation rates. A dating model of constant mixing with constant sedimentation rate was applied successfully to three independent records (unsupported ²¹⁰Pb, ¹³⁷Cs and ^239+240Pu), and provided the objective determination of mixing parameters and mass sedimentation rate. These results provide some insight into the fate of atmospheric inputs to this marine environment and, particularly, into the contribution from the Chernobyl accident.     

Geochemical signatures of two different coastal depositional environments within the same catchment

The geochemistry of lake (Renstradträsket) and estuarine (Pieni Pernajanlahti Bay) sediment was investigated in a medium sized watershed draining to the Gulf of Finland, Baltic Sea. Catchment land-use types were compared and found similar. Sediment cores were dated using ²¹⁰Pb- and ¹³⁷Cs-chronologies and analyzed for Al, K, Cu, Zn, Fe, Mn, phosphorus fractions, TN, TC and biogenic silica (BSi). Differences between the sediment cores were studied by using linear regression analysis and principal components analysis (PCA). Despite similarities in catchment land-use and history, the sediment geochemical profiles of the sites varied significantly. Some of the differences could be related to differences in chemical sedimentation environment (lacustrine versus estuarine). TP concentration was found to be positively correlated with sediment iron content in estuarine sediment but negatively correlated with Fe in lake sediment. In the estuarine core sedimentary iron was not correlated to lithogenic potassium and aluminum but in the lake core the iron seemed to be lithogenic in origin, as suggested by the strong positive correlations (r ² = 0.95–0.96) between these three variables. Most similarities among the cores were found in Al concentrations. Estuarine nutrient profiles appeared relatively monotonous compared to the lake core. This is probably due to more vigorous mixing of the sediments that may ensure more rapid and complete consumption of the organic matter deposited on the bottom of the estuary. Therefore the lake sediment appeared to preserve the historical record of eutrophication better. Biologically less active and more particle-bound materials like the trace metals Cu and Zn seemed to retain good records of anthropogenic impact also in the estuarine core. The study highlights the need to take the sedimentation environment into account when interpreting geochemical record.     

南极拜尔斯半岛企鹅粪土沉积物元素地球化学特征

拜尔斯半岛位于南极利文斯顿岛最西部,是南设得兰群岛中最大的无冰区。对采自拜尔斯半岛的一根长55 cm的企鹅粪土沉积柱P1进行了元素和同位素地球化学分析。通过对沉积物C/N、有机质来源和δ15N的分析,发现P1沉积剖面中有机质主要来源于企鹅粪。利用富集系数、相关性分析、主成分分析等统计分析方法,识别出该沉积剖面中P、F、Cu、Hg、As、S六种元素具有共同的来源,与企鹅粪的输入密切相关,并且这些元素与TOC和δ15N显著正相关,说明沉积剖面中这些元素含量主要受控于企鹅粪的输入程度。通过与长城站区阿德雷岛、东南极戴维斯站加德纳岛企鹅粪土沉积物的标型元素特征比较,发现上述三个地区的标型元素组合大体上一致,反映了整个南极地区企鹅粪土沉积物生物标型元素组合的共性。研究结果为进一步恢复该地区的企鹅种群数量演化,及其对气候变化的响应提供了可能。     

Holocene Lake Level Fluctuations Recorded in the Sediment Compositionof Lake Juusa,Southeastern Estonia

The main aim of this study was to reconstruct the history of water level fluctuations of a small dimictic lake during the Holocene based on the lithological and geochemical composition of sediments. We studied lithological and geochemical parameters in sediment cores extracted along a transect through Lake Juusa in southeastern Estonia. Analysis revealed that LOI₅₅₀ and CaCO₃ content in the accumulated sediment are dependent on water depth. At depths greater than 3 m, the relationship between organic carbon and CaCO₃ is inverse, whereas no relationship exists at shallower depths. Lake-level changes are well depicted on the grain-size distribution profiles and macrofossil composition. An increase in the >‰315μm fraction appeared during the initial phases of water level fluctuations, followed by an increase in the 100–315μm fraction. The >‰36μm fraction dominated the silt fraction. Higher OC/N ratios in shallow water sediments reflect the dominance of macrophytes vegetation.     

The cooling fluctuation events during Holocene in the tropical zone of China

Forty-eight samples are chosen to discuss the distribution in space and time of the cooling fluctuation events during Holocene in the tropical zone of China in this paper. The authors consider that the Neoglaciations II and III (or Cooling Event) have a widespread impact on the drop in temperature of 1–2 °C or less than 2 °C. The YD Event was dated at 11,300-10,200 a BP in the tropical mainland and its dating is 11,400-10,500 a BP in the sea area with a drop in temperature of 4–6 °C. The distribution of Event B and Neoglaciation I is taking a position of north, with a drop in temperature of 2.5–3.0 °C. The Cooling Event shows the temporality in time. The Cooling Event shows the limitation of regional distribution with a drop in temperature of less than 1.5°C. The more recent the cooling event is, the smaller the drop amplitude in temperature will be. In the eastern part of tropical zone seven events are complete in all varieties but the cooling fluctuation is weaker in the western part. In Hainan Island and South China Sea the appearance of cooling fluctuations is synchronous with each other.     

Paleolimnological records of recent glacier recession in the Rwenzori Mountains,Uganda-D. R. Congo

The status of tropical glaciers is enormously important to our understanding of past, present, and future climate change, yet lack of continuous quantitative records of alpine glacier extent on the highest mountains of tropical East Africa prior to the 20th century has left the timing and drivers of recent glacier recession in the region equivocal. Here we investigate recent changes (the last 150–700 years) in lacustrine sedimentation, glacier extent, and biogeochemical processes in the Rwenzori Mountains (Uganda- Democratic Republic of Congo) by comparing sedimentological (organic and siliciclastic component determined by loss-on-ignition; LOI) and organic geochemical profiles (carbon and nitrogen abundance, ratio, and isotopic composition of sedimentary organic matter) from lakes occupying presently glaciated catchments against similar profiles from lakes located in catchments lacking glaciers. The siliciclastic content of sediments in the ‘glacial lakes’ significantly decreases towards the present, whereas ‘non-glacial lakes’ generally show weak trends in their siliciclastic content over time, demonstrating that changes in the siliciclastic content of glacial lake sediments primarily record fluctuations in glacier extent. Radiometric dating of our sediment cores indicates that prior to their late 19th-century recession Rwenzori glaciers stood at expanded ‘Little Ice Age’ positions for several centuries under a regionally dry climate regime, and that recession was underway by 1870 AD, during a regionally wet episode. These findings suggest that the influence of late 19th century reductions in precipitation in triggering Rwenzori glacier recession is weaker than previously thought. Our organic geochemical data indicate that glacier retreat has significantly affected carbon cycling in Afroalpine lakes, but trends in aquatic ecosystem functioning are variable among lakes and require more detailed analysis.     

Five thousand years of sediment transfer in a high arctic watershed recorded in annually laminated sediments from Lower Murray Lake,Ellesmere Island,Nunavut, Canada

Sediments in Lower Murray Lake, northern Ellesmere Island, Nunavut Canada (81°21′ N, 69°32′ W) contain annual laminations (varves) that provide a record of sediment accumulation through the past 5000+ years. Annual mass accumulation was estimated based on measurements of varve thickness and sediment bulk density. Comparison of Lower Murray Lake mass accumulation with instrumental climate data, long-term records of climatic forcing mechanisms and other regional paleoclimate records suggests that lake sedimentation is positively correlated with regional melt season temperatures driven by radiative forcing. The temperature reconstruction suggests that recent temperatures are ~2.6°C higher than minimum temperatures observed during the Little Ice Age, maximum temperatures during the past 5200 years exceeded modern values by ~0.6°C, and that minimum temperatures observed approximately 2900 varve years BC were ~3.5°C colder than recent conditions. Recent temperatures were the warmest since the fourteenth century, but similar conditions existed intermittently during the period spanning ~4000–1000 varve years ago. A highly stable pattern of sedimentation throughout the period of record supports the use of annual mass accumulation in Lower Murray Lake as a reliable proxy indicator of local climatic conditions in the past.

A sediment record of trace metal loadings in the Upper Mississippi River

Sediment cores from Lake Pepin, a natural lake on the Upper Mississippi River, reveal the historical trends in trace metal use and discharge in the watershed. Lead-210 dated concentration profiles of trace metals (Ag, Cd, Cr, Cu, Hg, Pb, V, Zn) in sediment cores from throughout the lake generally showed low and stable concentrations prior to settlement (circa 1830), peak concentrations between 1940 and 1975, and substantial decreases thereafter. Whole-lake sediment accumulation rates increased greatly over the period of record, from 79,000 metric tons year⁻¹ prior to 1830, to 876,000 metric tons year⁻¹ during the 1990s. Whole-lake accumulation rates of most trace metals peaked in the 1960s but decreased sharply after that. Sediment and trace metal accumulation rates decreased in the downstream direction, and approximately two-thirds of the sediment and trace metal mass accumulated in Lake Pepin since 1800 was deposited in the upper 30% (by area) of the lake. The dramatic declines in trace metal concentrations and accumulation rates in Lake Pepin sediments since 1970 coincide with increased pollution control and prevention efforts throughout the watershed, including the implementation of secondary treatment at a large municipal wastewater treatment plant upstream. This is one of eight papers dedicated to the “Recent Environmental History of the Upper Mississippi River” published in this special issue of the Journal of Paleolimnology. D.R. Engstrom served as guest editor of the special issue.     

Records of large earthquakes in lake sediments along the North Anatolian Fault,Turkey

In 1999, the large surface-rupturing earthquakes of Izmit and Duzce completed a 60-year cycle that included a westward migration of nine consecutive large earthquake failures (>50 km surface rupture), which started with the 1939 Erzincan earthquake in eastern Turkey. In this study, we focused on seismic cycles and seismic risk predictability along the North Anatolian Fault (NAF). Toward the west end of the NAF (26°E–32°E, i.e. Bolu), large earthquake frequency is measured from either historic earthquake catalogs, or geologic records from isolated outcrops and marine sediment cores from the Marmara Sea. In comparison, the eastern part of the NAF zone (32°E–42°E) is less well documented by palaeo-seismologic archives. Thus, the sediment records of lake basins located on the eastern NAF zone constitute a unique opportunity for testing a new palaeo-seismologic approach. To this end, we used a diverse array of complementary methods involving: (1) a 600-km transect of fault-related lakes, (2) sedimentologic observations on cores from six lakes, and (3) a comparison between records of catastrophic sediment transfers in lakes (i.e. radionuclide chronomarkers and erosion tracers) and historic earthquake reports. Our study indicates that lakes along the NAF are sensitive geologic recorders of large surface-rupturing earthquakes (surface-wave magnitude (M _s) ≥ 6.9); smaller intensities are not recorded. The most responsive lake systems exhibit increases in sediment accumulation by a factor of >40 for a >3-m strike-slip displacement (M _s ≥ 7). However, based on results from the 1939 Erzincan earthquake (M _s = 7.8) chronostratigraphic marker, large surface-rupturing earthquakes are detected only by certain lake records and not by others. Matching multiple lake records along the NAF provides information both on the location of a surface rupture of a paleo-earthquake as well as its magnitude. Finally, the shallow lake basins along the NAF could potentially document cycles of large seismic events for at least the late Holocene.     

A test of the possible influence of seabird activity on the <Superscript>210</Superscript>Pb flux in high Arctic ponds at Cape Vera,Devon Island,Nunavut: implications for radiochronology

A large seabird colony of northern fulmars (Fulmarus glacialis) at Cape Vera on Devon Island in the Canadian high Arctic has been shown to act as an effective biological pump, transporting large quantities of marine-derived nutrients and contaminants to the ponds beneath their nesting sites. Previous research has shown that seabirds also have the potential to elevate radionuclide concentrations in their immediate surroundings. Here, we assess the influence of the Cape Vera seabird colony on the ²¹⁰Pb budgets of six affected ponds and one control site, and discuss potential implications with respect to ²¹⁰Pb dating methodologies. In general, fluxes of ²¹⁰Pb at Cape Vera were similar to, or less than, those measured at other Arctic locations not influenced by seabirds. Plots of unsupported ²¹⁰Pb activity versus depth showed a number of non-monotonic features in all sediment cores, necessitating the use of the constant-rate-of-supply (CRS) model to derive age-depth profiles. We conclude that seabird activity has not dramatically increased the ²¹⁰Pb flux to the ponds at Cape Vera. Overall, the low flux of excess ²¹⁰Pb made accurate dating problematic for some of the study cores, necessitating the use of independent dating markers (e.g., ¹³⁷Cs and PCB concentrations) to verify the reliability of the chronologies.     

东南极戴维斯站企鹅粪土沉积物有机地球化学特征

研究了位于东南极西福尔丘陵地区Gardner Island企鹅粪土的沉积泥芯DG2的分子地球化学组成特征。DG2沉积物的正烷烃以短链为主,主要来源可能为淡水湖相沉积的藻类和细菌输入。脂肪酸组分偶奇优势明显,以C16,C18和C24一元饱和脂肪酸为主,主要来源可能是浮游动物、细菌及水生苔藓;不饱和脂肪酸含量很低,以C18∶1(Δ9)为主,表明沉积源单一稳定,无大波动。醇类组分以高浓度的植醇、胆甾烷醇和胆甾醇为主,分别代表了植被和企鹅数量,指示了研究区域历史时期的生态变化。综合DG2的生物标志物特征,反映该沉积物的有机质主要来源于企鹅粪、细菌和藻类;沉积环境在不同深度也有变化,0-30cm为氧化环境,30-63cm为还原环境。