Stimulation of gaseous phosphine production from Antarctic seabird guanos and ornithogenic soils

Matrix-bound phosphine （MBP） is a general term used to indicate non-gaseous reduced phosphorus compounds that are transformed into phosphine gas upon reaction with bases or acids. Antarctic seabird guanos and ornithogenic soils were used as materials to compare the different digestion methods for transforming matrix-bound phosphine into phosphine gas. The results demonstrated that more phosphine gas in most of Antarctic environmental materials was formed of matrix-bound phosphine by caustic digestion than by acidic digestion. The comparative study on different digestion methods also revealed that the fraction of MBP converted to gaseous phosphine during the digestion depended on the temperature. The optimal digestion temperature was close to 70℃and the optimal digestion time was about 20 min. Acidic conditions were more favorable for the release of matrix-bound phosphine compared to the neutral conditions. A proper water dilution can increase the production and emission of phosphine from the Antarctic penguin guanos.

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.

Preliminary studies on nitrous oxide emissions from the ornithogenic soils on Xi-sha atoll,South China Sea

The preliminary measurements of nitrous oxide fluxes from the ornithogenic soils on tropical Xi-sha atoll were made using a closed chamber technique for the first time. N_2O fluxes from the ornithogenic soils ranged from 1 8 to 40 3 μg/(m^2\5h) on Dong Island and 3 2 to 20 4 μg/(m^2·h) on Yongxing Island and their flux averaged 11 0 μg/(m^2·h) and 8 3 μg/(m^2·h), respectively. N_2O fluxes from two wetland sites in salt marsh of Dong Island were approximately one order of magnitude lower than those from the ornithogenic soils and averaged 2 1 μg/(m^2·h) and 2 4 μg/(m^2·h). The diurnal variation cycle in the fluxes was obtained at the observation sites; the N_2O flux increased with the increase in soil temperature. The sudden increase in soil moisture greatly stimulated N_2O emission from the ornithogenic soils on Dong Island due to the heavy rainfall. The undisturbed soils showed the lower N_2O fluxes and the average was 4 8 μg/(m^2·h) and the soils via the reclamation showed the higher N_2O fluxes and the average was 16 6 μg/(m^2·h) on Yongxing Island, suggesting that the changes of land use have an important effect on N_2O fluxes from the ornithogenic soils. In addition, the N_2O fluxes at the different sites showed high spatial variations. The fluxes were positively correlated with the concentrations of NO^-_3, PO~ 3- _4 and Mn in the soils. The negative correlation between the fluxes and total S concentration in the ornithogenic soils was also found for the first time. Coastal soils or sediments constitute an important source of global atmospheric N_2O and the increases in nitrogen loading from seabird guanos will lead to significant increases in the flux of this atmospherically active gas.

Preliminary studies on methane flux from the ornithogenic soils on Xi-sha atoll, South China Sea

Methane flux from the ornithogenic soils was preliminarily measured by closed chamber method on Xi-sha atoll, South China Sea during March 10 to April 11, 2003 for the first time. The CH4 flux ranged from - 226.7 μg/（m^2 ·h） to 226.3 μg/（m^· h） at the observation sites on Dong Island. High atmospheric CH4 consumption was observed from the ornithogenic soils on sunny days. CH4 uptake rates showed the highest value after the midday and they had a strong positive correlation with soil temperatures. Under the same weather conditions, the CH4 fluxes were also observed from the intact and disturbed soils on Yongxing Island. Results showed that the intact soils with natural vegetation also showed high atmospheric CH4 consumption and the average flux was - 141.8 μg/（ m^2· h）. However, disturbed soils via anthropogenic reclamation showed CH4 emissions and the average flux was 441 .7 μg/（ m^2· h）. Therefore land use changes may have an important effect on the CH4 fluxes from the tropical ornithogenic soils. In addition, different observation sites show a high spatial variation in CH4 fluxes. The wetland in salt marsh showed the CH4 emission on Dong Island, and the dry soil sites all showed high atmospheric CH4 consumption, suggesting that CH4 fluxes were predominantly controlled by soil water regime. The effects of soil chemical properties on CH4 fluxes were also analyzed and discussed in this paper.

Potential methane production rates and its carbon isotopic composition from ornithogenic tundra soils in coastal Antarctic

Methane （CH4） is one of important greenhouse gases with chemical activity. The determination of isotopic compositions for CH4 emitted from the soils helps us to understand its production mechanisms. CH4 isotope measurements have been conducted for different types of global terrestrial ecosystems. However, no isotopic data of CH4 have been reported from Antarctic tundra soils. In this paper, ornithogenic soil profiles were collected from four penguin colonies, and potential CH4 production rates and its 13C ratio （δ13C） were investigated based upon laboratory incubation experiments. The mean CH4 production rates are highly variable in these soil profiles, ranging from 0.7 to 20.3μg CH4-C kg-1·h-1. These omithogenic soils had high potential production rates of CH4 under ambient air incubation or under N2 incubation, indicating the importance of potential CH4 emissions from penguin colonies. Most of the soil samples had higher δ13C-CH4 under N2 incubation （-39.28%-43.53%） than under the ambient air incubation （-42.81%-57.19%）. Highly anaerobic conditions were conducive to the production of CI-h enriched in 13C, and acetic acid reduction under N2 incubation might be a predominant source for soil CH4 production. Overall the δ13C-CH4 showed a significant negative correlation with CH4 production rates in ornithogenic tundra soils under N2 incubation （R2=0.41,p〈0.01） or under the ambient air incubation （RE=0.50,p〈0.01）. Potential CH4 production from ornithogenic soils showed a significant positive correlation with total phosphorus （TP） and NH4＋-N contents, pH and soil moisture （Mc）, but the δ13C-CH4 showed a significant negative correlation with TP and NH4＋ -N contents, pH and Me, indicating that the deposition amount of penguin guano increased potential CH4 production rates from tundra soils, but decreased the δ13C-CH4. The CH4 emissions from the ornithogenic soils affect carbon isotopic compositions of atmospheric CH4 in coastal Antarctica.

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. Sistosterol, 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 preference, and the main unsaturated fatty acid is C18：1 acid. The α-hydroxyl acids and ω-hydroxyl tatty acids were also detected in the sediments. In summary, the organic matters in the YN sediments were from the adjacent coal mines, bird feces, and plants.

The identification and comparison of the bio-elements of the penguin ornithogenic sediments sample from Davis Station and Great Wall Station

During CHINARE-22 in austral summer of 2005-2006, a lake sediment core named DG4, which is impacted by penguin droppings, was retrieved from a lake catchment in Gardner Island of Vestfold Hills, East Antarctica. In this study, the concentrations of characteristic elements in the core, local bedrocks and fresh penguin guanos were determined. P, Se, F, S, As, Sr and Cu in DG4 were identified as the bio-element assemblage by R-clustering analysis and compared with those in the local bedrocks and fresh guanos, the results are similar to Y2 in Ardley Island, Antarctic Peninsula. On this basis, P and Se were identified as the optimum bio-elements in DG4 and F, P and S were identified in Y2, respectively. This work will provides the foundation for reconstructing the past penguin populations in Gardner Island of Vest- fold Hills, East Antarctica and comparing the penguin population dynamics between East Antarctica and Antarctic Peninsula.

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-versusdepth 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.

Millennial mercury records derived from ornithogenic sediment on Dongdao Island,South China Sea

Two ornithogenic sediment cores,which have a time span of 1000 years and are influenced by red-footed booby （Sula sula）,were collected from Dongdao Islands,South China Sea.The determined mercury concentrations of the two cores show similar and substantial fluctuations during the past millennium,and the fluctuations are most likely caused by the changes in mercury level of the ocean environment and in anthropogenic Hg emission.For the past 500 years,the mercury concentration in the red-footed booby excrement has a striking association with global anthropogenic mercury emission.The mercury concentration increased rapidly after AD 1600 in corresponding to beginning of the unparalleled gold and silver mining in South Central America that left a large volume of anthropogenic mercury pollution.Since the Industrial Revolution,the mercury level has increased at a fast pace,very likely caused by modern coal combustion,chlor-alkali and oil refining industries.The comparison of mercury profiles from different places on earth suggested that anthropogenic mercury pollution after the Industrial Revolution is more severe in Northern Hemisphere than in Antarctica.

Heavy Metal Distributions and Source Tracing in the Lacustrine Sediments of Dongdao Island,South China Sea

The levels and depth distributions of As, Cd, Cu, Zn, Pb, Hg, Fe and Mn in two sediment cores DY2 and DY4 collected from the ＂Cattle Pond＂ of Dongdao Island, South China Sea, were determined and analyzed with the main objective to identify the sources of these elements and evaluate the corresponding sedimentological and geochemical processes. Lithological characters and sedimentary parameters such as LOI950℃, CaO, LOI550℃ and TOC indicate that the depth of 96 cm and 87 cm are the critical points for DY2 and DY4 cores, respectively. As, Cd, Cu, Zn, Hg and P are remarkably enriched in the ornithogenic sediments above the critical depth points; their concentration-versus-depth profiles are similar to those of TOC and LOI550℃; the ratios of As, Cd, Cu, Zn, Hg over Ca are significantly correlated with P/Ca. Statistical and comparative analyses of these elements＇ levels in the ornithogenic sediments of DY2 and DY4 strongly suggest that seabird droppings are the main source of these elements. Additionally, for the upper sediment layers of DY2 and DY4 cores, Fe oxide sorption mechanism, like organic matter, may also play an important role in the abundances of heavy metals. Heavy metal Pb has geochemical characteristics distinctly different from those of As, Cd, Cu, Zn, Hg and P, and its isotope composition indicates an origin of anthropogenic emissions from the surrounding countries. These geochemical characteristics in the orinithogenic sediments of Xisha Islands are compared with the studies in the remote Antarctic and Arctic regions.