Molecular organic geochemistry of ornithogenic sediment from Svalbard, Arctic

The molecular biomarker compositions of the ornithogenic sediments(YN) , from Svalbard, Arctic were investigated. The results showed that n-alkanes had a bimodal pattern and their odd-even preference was not obvious. The alkanes contained unresolved complex mixtures (UCM) and relatively high levels of pristine and retene, indicating pollution from the nearby coal mines. The n-alkanols in the sediments had even-to-odd preference, and they might originate mainly from modern biota. Sitosterol, the main sterol in herbivores feces, was the dominant sterol, indicating that sitosterol might be a good biomarker of input from the birds feces in the sediments. The fatty acids of the sediments showed even-to-odd p reference, and the main unsaturated fatty acid is C18∶1 acid. Theα-hydroxyl acids and ω-hydroxyl fatty acids were also detected in the sediments. In summary, the organic matters in the YN sediments were from the adjacent coalmines, bird feces, and p lants

Feasibility of using reflectance spectroscopy for the analysis of bio-element concentrations in Antarctic ornithogenic sediments

Compared with traditional chemical analysis methods, reflectance spectroscopy has the advantages of speed, minimal or no sample preparation, non-destruction, and low cost. The present study explored the application of the reflectance spectroscopy within near ultraviolet-visible-near infrared region to predict bio-element compositions in the ornithogenic sediments from the maritime Antarctic. A total of 106 samples were taken from four ornithogenic sediment cores on the Ardley Island of Antarctica, 68 samples were used for building calibration equation, and 38 for prediction of nine bio-elements including P, Ca, Cu, Zn, Se, Sr, Ba, F and S. Three multivariate statistical analysis techniques, including stepwise multiple linear regression (Stepwise-MLR), principal component regression(PCR) and partial least squares regression (PLS) were used to develop mathematical relationships between the spectral data and the chemical reference data. The results showed that the regression models constructed by PCR and PLS models have no significant differences, and obviously supervisor to Stepwise-MLR. The correlations between spectra-predicted and chemically analyzed concentrations of nine bio-elements are statistically significant, and the concentration-versus-depth profiles predicted from reflectance spectra using PLS calibration model are consistent with those from actual chemical analysis. These results demonstrated the feasibility of using reflectance spectroscopy to infer bio-element concentrations in the ornithogenic sediments, and thus it is suggested that the reflectance spectroscopy could provide a rapid and valuable technique to indirectly identify whether the sediments were influenced by penguin droppings in the Antarctic region

Potential application of biogenic silica as an indicator of paleo-primary productivity in East Antarctic lakes

We collected two lake sediment cores (MC and DM) from the East Antarctic region for analysis of biogenic silica and other biogeochemical parameters (e.g., organic matter, C, N, S, H). Based on synthetically comparative research, we focused on the potential application of biogenic silica (BSi) for the reconstruction of paleo-primary productivity in the East Antarctic lakes. Analytical results showed that a large number of diatoms were well preserved in the freshwater lake sediments, and that concentrations of biogenic silica displayed notable fluctuations over different water depths. The content of biogenic silica had a consistent profile over water depth, and this pattern changed with organic matter, reflecting their potential as eco-environmental proxies. Low levels of BSi and organic matter indicated reduction of lake algal production, and corresponded to decreased lake primary productivity. Due to the fragile ecosystem state and limited contribution of terrestrial organic matter in the East Antarctic lakes, the contents of biogenic silica in the lacustrine sediments can sensitively indicate the evolutionary history of paleo primary productivity. Overall, BSi is an ideal proxy for the reconstruction of past eco-environmental change recorded in the lacustrine sediments on East Antarctica

Holocene climate change and anthropogenic activity records in Svalbard: a unique perspective based on Chinese research from Ny-Ålesund

Climate change in the Arctic region is more rapid than that in other areas owing to Arctic amplification. To better understand climate change and the driving mechanisms, long-term historical reconstructions throughout the Holocene and high-resolution records of the past few hundred years are required. Intense anthropogenic activities in the Arctic have had a great impact on the local environment. Here, we review the Holocene climate change record, responses of the ecosystems to climate change, and the anthropogenic impacts on the environment based mainly on Chinese research from Ny-Ålesund. Climate reconstruction studies from Svalbard have revealed several cold episodes during the Holocene, which are consistent with ice rafting events in the North Atlantic region and glacier activity from Greenland, Iceland, and Svalbard. The ecosystem also showed corresponding responses to climate change, especially during the late Holocene. Over recent decades, anthropogenic activities have caused serious pollution and deterioration to the local environment in Svalbard in areas frequented by people. Greater environmental protection is therefore needed to reduce the anthropogenic impacts on the local environment

The changes of pigment contents and their environmental implications in the lake sediments of Ny-Ålesund, Svalbard, the Arctic

According to palaeoclimatic and modern instrumental data, numerous studies have indicated that the Arctic climate has undergone a significant warming during the past 100 years, and this may lead to significant impact on the fragile lake ecosystem. In this study, we collected a lake sediment core from the Ny-Ålesund of Svalbard and determined the concentrations of four pigments including chlorophyll derivatives, total carotenoids, oscillaxanthin and myxoxanthophyll in the sediments. Combined with other physical and chemical proxies such as calcium carbonate, total organic carbon, biogenic silicon etc.,we have reconstructed the historical changes of lacustrine primary productivity in Ny-Ålesund, especially for the past 100 years. The results showed that during the period of Little Ice Age(LIA), the climate was unfavorable for the growth of the lake algae, and thus the lacustrine productivity declined. This result was supported by the relatively low contents of pigment and biogenic silica in the sediments. In contrast, the contents of total organic carbon(TOC) and sediment pigments increased significantly in the upper 5cm (~1890AD), reflecting the rapid growth of the lake algae, thus the great increase of lacustrine primary productivity, corresponding to the warming climate after LIA. However, the biogenic silica in the upper sediments still had a relatively low level, and this might be related to the growth competition with other algae species. Over the past 100 years, the ratio of Osc/Myx in the sediments decreased continuously, indicative of durative increase of myxoxanthophyll in blue-green algal pigments, and this might imply that the human activity had enhanced the nutrition level of the lake in the Arctic region

Preliminary evidence for 17 coastal terraces on Fildes Peninsula, King George Island, Antarctica

This study confirms the presence of 17 coastal terraces on Fildes Peninsula, Antarctica based on field observations and grain size analysis. The terraces formed by isostatic uplift during climate warming and glacier melting, and each level corresponds to a relatively stable period of climate. The grain size characteristics indicate an overlapping sedimentary origin for the sediments on the coastal terraces. The consistency of regional sea level rise, climate change, and glacial area suggest the presence of similar coastal terraces on King George Island since 18.0 ka

Alkaline phosphatase activity in ornithogenic soils in polar tundra

Phosphatase plays an important role in the microbial liberation of phosphorus in soil systems. In this study, alkaline phosphatase activity (APA) was investigated from tundra ornithogenic soil profiles in Antarctica and Arctic. The organic carbon (TOC), total nitrogen (TN), and phosphorus fractions and pH were also analyzed in these soils. The correlation between APA and soil chemical properties is discussed. In almost all the soil profiles, APA showed the same variation patterns. The maximum APA appeared in the surface layers, and decreased with soil depth. The APA ranged from 1.00 ppm to 1 403.5 ppm with an average of approximately 408.3 ppm. The APA showed a significant positive correlation with TOC (r =0.70, p <0.001), TN (r =0.43, p =0.002), total phosphorus (r =0.39, p <0.05)and inorganic phosphorus (r =0.40, p =0.037), indicating that they were predominant factors affecting APA in the polar tundra soils. In addition, APA showed a significant negative correlation with Cu and Zn concentrations in the soils, indicating that Cu and Zn may inhibit APA. Our results showed that APA could be used as an important indicator for soil fertility in polar tundra ecosystems

Observations of stratospheric ozone above Ny-Ålesund in the Arctic, 2010–2011

Stratosphere ozone depletion above the Arctic region has drawn increased attention recently. Here we present stratospheric ozone column densities above Ny-Ålesund in the Arctic during summer 2010 and 2011, based on a self-developed passive differential optical absorption spectroscopy (DOAS) technique. By analyzing the received scattered solar spectrum, daily variations of ozone vertical column densities (VCDs) were obtained and correlated with satellite-borne ozone monitoring results and ozone sonde data. The comparisons showed good correlation, confirming the feasibility of DOAS in high-latitude Arctic regions. The preliminary analysis also demonstrated that abnormal low-level ozone columns found in spring 2011 had negative impacts on total ozone column densities over the entire year. The loss of stratospheric ozone may be correlated with low stratospheric temperatures, where heterogeneous atmospheric reactions were active

Temporal and spatial variations of atmospheric methane concentration and δ13 C-CH4 near the surface on the Millor Peninsula, East Antarctica

During the 22nd Chinese Antarctic Research Expedition (CHINARE222, 2005/06) , the atmospheric gas samples near the surface were taken on the Millor Peninsula and adjacent areas, east Antarctica, using Tedlar gas bags. The methane(CH4) concentration and δ13 C-CH4 in those samples were analyzed in the laboratory. The average value of atmospheric CH4 concentration on this peninsula was (1.87 ± 0.12) × 10(-6) , slightly higher than the global average CH4 concentration. The summertime variation of CH4 concentrations showed a large fluctuation, corresponding to the variation of air temperatures. The average δ13 C-CH4 was ( -38.26 ± 0.52) ‰. CH4 concentrations and δ13 C-CH4 at different sites varied from 1.74 × 10(-6) to 2.56 ×10(-6) and from -39.31‰ to - 31.25‰, respectively. The factors affecting CH4 concentrations and δ13 C-CH4 values have also been discussed in this study

Organic geochemical characterization on a seal excrement sediment core from Fildes Peninsula, Western Antarctica

Organic geochemical analysis was performed on a sediment core HN1 from Fildes Peninsula on King George Island, Western Antarctica. Short-chain n-alkanes were the main components of the aliphatic hydrocarbons present, and they were likely to be from algae and bacteria; n-C23 was likely derived from moss. Fecal sterols and phytol dominated the alcohol composition, and may have come from seal feces and vegetation, respectively. The fluctuations in their concentrations generally have responded to historical changes in the ecosystems near the region. The even-carbon fatty acids, such as n-C16, n-C18 and n-C24, dominated the alkenoic acid composition, which mainly originated from bacteria, moss and zooplankton. The low concentrations of unsaturated fatty acids showed a predominance of C16:1 and C18:1 unsaturated acids, and demonstrated that the sediment was well preserved and had a simple and stable source of organic materials