scholarly journals Geochemical zones and environmental gradients for soils from the central Transantarctic Mountains, Antarctica

2021 ◽  
Vol 18 (5) ◽  
pp. 1629-1644
Author(s):  
Melisa A. Diaz ◽  
Christopher B. Gardner ◽  
Susan A. Welch ◽  
W. Andrew Jackson ◽  
Byron J. Adams ◽  
...  
Keyword(s):  
Random Forest ◽  
Environmental Gradients ◽  
Strong Dependence ◽  
Water Soluble ◽  
Dry Valleys ◽  
Lower Zone ◽  
Soil Biodiversity ◽  
Outlet Glacier ◽  
Transantarctic Mountain ◽  
Transantarctic Mountains

Abstract. Previous studies have established links between biodiversity and soil geochemistry in the McMurdo Dry Valleys, Antarctica, where environmental gradients are important determinants of soil biodiversity. However, these gradients are not well established in the central Transantarctic Mountains, which are thought to represent some of the least hospitable Antarctic soils. We analyzed 220 samples from 11 ice-free areas along the Shackleton Glacier (∼ 85∘ S), a major outlet glacier of the East Antarctic Ice Sheet. We established three zones of distinct geochemical gradients near the head of the glacier (upper), its central part (middle), and at the mouth (lower). The upper zone had the highest water-soluble salt concentrations with total salt concentrations exceeding 80 000 µg g−1, while the lower zone had the lowest water-soluble N:P ratios, suggesting that, in addition to other parameters (such as proximity to water and/or ice), the lower zone likely represents the most favorable ecological habitats. Given the strong dependence of geochemistry on geographic parameters, we developed multiple linear regression and random forest models to predict soil geochemical trends given latitude, longitude, elevation, distance from the coast, distance from the glacier, and soil moisture (variables which can be inferred from remote measurements). Confidence in our random forest model predictions was moderately high with R2 values for total water-soluble salts, water-soluble N:P, ClO4-, and ClO3- of 0.81, 0.88, 0.78, and 0.74, respectively. These modeling results can be used to predict geochemical gradients and estimate salt concentrations for other Transantarctic Mountain soils, information that can ultimately be used to better predict distributions of soil biota in this remote region.

scholarly journals Geochemical zones and environmental gradients for soils from the Central Transantarctic Mountains, Antarctica

2020 ◽  
Author(s):  
Melisa A. Diaz ◽  
Christopher B. Gardner ◽  
Susan A. Welch ◽  
W. Andrew Jackson ◽  
Byron J. Adams ◽  
...  
Keyword(s):  
Environmental Gradients ◽  
Strong Dependence ◽  
Water Soluble ◽  
Dry Valleys ◽  
Lower Zone ◽  
Soil Geochemistry ◽  
Soil Biodiversity ◽  
Outlet Glacier ◽  
Transantarctic Mountain ◽  
Transantarctic Mountains

Abstract. Previous studies have established links between biodiversity and soil geochemistry in the McMurdo Dry Valleys, Antarctica, where environmental gradients are important determinants of soil biodiversity. However, these gradients are not well established in the Central Transantarctic Mountains, which are thought to represent some of the least hospitable Antarctic soils. We analyzed 220 samples from 11 ice-free areas along the Shackleton Glacier (~ 85 °S), a major outlet glacier of the East Antarctic Ice Sheet. We established three zones of distinct geochemical gradients near the head of the glacier (upper), central (middle), and at the mouth (lower). The upper zone had the highest water-soluble salt concentrations with total salt concentrations exceeding 80,000 µg g-1, while the lower zone had the lowest water-soluble N : P ratios, suggesting that, in addition to other parameters (such as proximity to water/ice), the lower zone likely represents the most favorable ecological habitats. Given the strong dependence of geochemistry with geographic parameters, we established multiple linear regression and random forest models to predict soil geochemical trends given latitude, longitude, elevation, distance from the coast, distance from the glacier, and soil moisture (variables which can be inferred from remote measurements). Confidence in our model predictions was moderately high, with R2 values for total water-soluble salts, water-soluble N : P, ClO4-, and ClO3- of 0.51, 0.42, 0.40, and 0.28, respectively. These modeling results can be used to predict geochemical gradients and estimate salt concentrations for other Transantarctic Mountain soils, information that can ultimately be used to better predict distributions of soil biota in this remote region.

Remediation-related monitoring of heavy metal concentration of contaminated Technosol using hyperspectral measurements

2021 ◽  
Author(s):  
Friederike Kaestner ◽  
Magdalena Sut-Lohmann ◽  
Thomas Raab ◽  
Hannes Feilhauer ◽  
Sabine Chabrillat
Keyword(s):  
Heavy Metal ◽  
Random Forest ◽  
Metal Concentration ◽  
Strong Dependence ◽  
Scatter Correction ◽  
Heavy Metal Concentration ◽  
Standard Normal Variate ◽  
Multiplicative Scatter Correction ◽  
Second Derivatives ◽  
Standard Normal

<p>Across Europe there are 2.5 million potentially contaminated sites, approximately one third have already been identified and around 15% have been sanitized. Phytoremediation is a well-established technique to tackle this problem and to rehabilitate soil. However, remediation methods, such as biological treatments with microorganisms or phytoremediation with trees, are still relatively time consuming. A fast monitoring of changes in heavy metal content over time in contaminated soils with hyperspectral spectroscopy is one of the first key factors to improve and control existing bioremediation methods.</p><p>At former sewage farms near Ragow (Brandenburg, Germany), 110 soil samples with different contamination levels were taken at a depth between 15-20 cm. These samples were prepared for hyperspectral measurements using the HySpex system under laboratory conditions, combing a VNIR (400-1000 nm) and a SWIR (1000-2500 nm) line-scan detector. Different spectral pre-processing methods, including continuum removal, first and second derivatives, standard normal variate, normalisation and multiplicative scatter correction, with two established estimation models such as Partial Least Squares Regression (PLSR) and Random Forest Regression (RFR), were applied to predict the heavy metal concentration (Ba, Ni, Cr, Cu) of this specific Technosol. The coefficient of determination (R2) shows for Ba and Ni values between 0.50 (RMSE: 9%) and 0.61 (RMSE: 6%) for the PLSR and between 0.84 (RMSE: 0.03%) and 0.91 (RMSE: 0.02%) for the RFR model. The results for Cu and Cr show values between 0.57 (RMSE: 17.9%) and 0.69 (RMSE: 15%) for the PLSR and 0.86 (0.12%) and 0.93 (0.01%) for the RFR model. The pre-processing method, which improve the robustness and performance of both models best, is multiplicative scatter correction followed by the standard normal variate for the first and second derivatives. Random Forest in a first approach seems to deliver better modeling performances. Still, the pronounced differences between PLSR and RFR fits indicate a strong dependence of the results on the respective modelling technique. This effect is subject to further investigation and will be addressed in the upcoming analysis steps.</p>

scholarly journals Spectral properties and photophysical behaviour of water soluble cationic Mg(II) and Al(III) phthalocyanines

2014 ◽  
Vol 12 (3) ◽  
pp. 403-415 ◽  
Author(s):  
Mopelola Idowu ◽  
Yasin Arslanoğlu ◽  
Tebello Nyokong
Keyword(s):  
Aqueous Solution ◽  
Aqueous Medium ◽  
Spectral Properties ◽  
Photophysical Properties ◽  
Strong Dependence ◽  
Water Soluble ◽  
Quantum Yields ◽  
Fluorescence Lifetimes ◽  
High Solubility ◽  
Medium Ph

AbstractPeripherally and non-peripherally tetrasubstituted-[(N-methyl-2-pyridylthio)]phthalocyaninato magnesium (II) (5 and 6) and chloro aluminium (III) (7 and 8) tetraiodide have been synthesized and characterized. The photophysical properties of the complexes in dimethyl sulfoxide (DMSO) and aqueous medium in the presence and absence of cremophore EL have been studied. These complexes show high solubility in aqueous medium though they were aggregated. The triplet state quantum yields (FT) and the triplet lifetimes (tT) were found to be higher in DMSO with ΦT ranging from 0.32 to 0.51, while tT ranged from 282 to 622 ms in DMSO, compared to aqueous medium (pH 7.4 buffer) where ΦT ranged from 0.15 to 0.19 and tT from 26 to 35 ms. Addition of cremophore EL in aqueous solution resulted in partial disaggregation and increased photoactivity. The fluorescence lifetimes of the complexes showed strong dependence on their immediate environment. The ionic magnesium(II) and aluminium(III) phthalocyanines strongly bind to bovine serum albumin (BSA).

Supplementary material to "Geochemical zones and environmental gradients for soils from the Central Transantarctic Mountains, Antarctica"

2020 ◽  
Author(s):  
Melisa A. Diaz ◽  
Christopher B. Gardner ◽  
Susan A. Welch ◽  
W. Andrew Jackson ◽  
Byron J. Adams ◽  
...  
Keyword(s):  
Environmental Gradients ◽  
Supplementary Material ◽  
Transantarctic Mountains

scholarly journals Dicarboxylic acids, metals and isotopic compositions of C and N in atmospheric aerosols from inland China: implications for dust and coal burning emission and secondary aerosol formation

2010 ◽  
Vol 10 (13) ◽  
pp. 6087-6096 ◽  
Author(s):  
G. Wang ◽  
M. Xie ◽  
S. Hu ◽  
S. Gao ◽  
E. Tachibana ◽  
...  
Keyword(s):  
Organic Carbon ◽  
Strong Dependence ◽  
Inversion Layer ◽  
Stable Carbon Isotope ◽  
Dicarboxylic Acids ◽  
Water Soluble ◽  
Total Carbon ◽  
Aerosol Formation ◽  
Coal Burning ◽  
Isotopic Compositions

Abstract. Dicarboxylic acids (C2–C10), metals, elemental carbon (EC), organic carbon (OC), and stable isotopic compositions of total carbon (TC) and total nitrogen (TN) were determined for PM10 samples collected at three urban and one suburban sites of Baoji, an inland city of China, during winter and spring 2008. Oxalic acid (C2) was the dominant diacid, followed by succinic (C4) and malonic (C3) acids. Total diacids in the urban and suburban areas were 1546±203 and 1728±495 ng m−3 during winter and 1236±335 and 1028±193 ng m−3 during spring. EC in the urban and the suburban atmospheres were 17±3.8 and 8.0±2.1 μg m−3 during winter and 20±5.9 and 7.1±2.7 μg m−3 during spring, while OC at the urban and suburban sites were 74±14 and 51±7.9 μg m−3 in winter and 51±20 and 23±6.1 μg m−3 in spring. Secondary organic carbon (SOC) accounted for 38±16% of OC in winter and 28±18% of OC in spring, suggesting an enhanced photochemical production of secondary organic aerosols in winter under an inversion layer development. Total metal elements in winter and spring were 34±10 and 61±27 μg m−3 in the urban air and 18±7 and 32±23 μg m−3 in the suburban air. A linear correlation (r2>0.8 in winter and r2>0.6 in spring) was found between primary organic carbon (POC) and Ca2+/Fe, together with a strong dependence of pH value of sample extracts on water-soluble inorganic carbon, suggesting fugitive dust as an important source of the airborne particles. Polycyclic aromatic hydrocarbons (PAHs), sulfate, and Pb in the samples well correlated each other (r2>0.6) in winter, indicating an importance of emissions from coal burning for house heating. Stable carbon isotope compositions of TC (δ13C) became higher with an increase in the concentration ratios of C2/OC due to aerosol aging. In contrast, nitrogen isotope compositions of TN (δ15N) became lower with an increases in the mass ratios of NH4+/PM10 and NO3−/PM10, which is possibly caused by an enhanced adsorption and/or condensation of gaseous NH3 and HNO3 onto particles.

Fragment of an ancient outlet glacier system near the top of the Transantarctic Mountains

Geology ◽  
2003 ◽  
Vol 31 (9) ◽  
pp. 821 ◽  
Author(s):  
Stephen R. Hicock ◽  
Peter J. Barrett ◽  
Philip J. Holme
Keyword(s):  
Outlet Glacier ◽  
Glacier System ◽  
Transantarctic Mountains

scholarly journals An englacial hydrologic system of brine within a cold glacier: Blood Falls, McMurdo Dry Valleys, Antarctica

2017 ◽  
Vol 63 (239) ◽  
pp. 387-400 ◽  
Author(s):  
JESSICA A. BADGELEY ◽  
ERIN C. PETTIT ◽  
CHRISTINA G. CARR ◽  
SLAWEK TULACZYK ◽  
JILL A. MIKUCKI ◽  
...  
Keyword(s):  
Latent Heat ◽  
Flow Direction ◽  
Salt Content ◽  
Mcmurdo Dry Valleys ◽  
Dry Valleys ◽  
Outlet Glacier ◽  
Air Temperatures ◽  
Radio Echo Sounding ◽  
Hydrologic System ◽  
Taylor Glacier

ABSTRACTTaylor Glacier hosts an active englacial hydrologic system that feeds Blood Falls, a supraglacial outflow of iron-rich subglacial brine at the terminus, despite mean annual air temperatures of −17°C and limited surface melt. Taylor Glacier is an outlet glacier of the East Antarctic ice sheet that terminates in Lake Bonney, McMurdo Dry Valleys. To image and map the brine feeding Blood Falls, we used radio echo sounding to delineate a subhorizontal zone of englacial brine upstream from Blood Falls and elongated in the ice flow direction. We estimate volumetric brine content in excess of 13% within 2 m of the central axis of this zone, and likely much higher at its center. Brine content decreases, but remains detectable, up to 45 m away along some transects. Hence, we infer a network of subparallel basal crevasses allowing injection of pressurized subglacial brine into the ice. Subglacial brine is routed towards Blood Falls by hydraulic potential gradients associated with deeply incised supraglacial valleys. The brine remains liquid within the subglacial and englacial environments through latent heat of freezing coupled with elevated salt content. Our findings suggest that cold glaciers could support freshwater hydrologic systems through localized warming by latent heat alone.

scholarly journals Buried ice in Kennar Valley: a late Pleistocene remnant of Taylor Glacier

2017 ◽  
Vol 29 (3) ◽  
pp. 239-251 ◽  
Author(s):  
Kate M. Swanger
Keyword(s):  
Late Pleistocene ◽  
Ice Cores ◽  
Dry Valleys ◽  
Patterned Ground ◽  
Outlet Glacier ◽  
Air Bubble ◽  
Isotopic Analyses ◽  
Stable Isotopic ◽  
Glacier Ice ◽  
Taylor Glacier

AbstractBuried glacier ice is common in the McMurdo Dry Valleys and under ideal climatic and geomorphological conditions may be preserved for multimillion-year timescales. This study focuses on the analysis of ~300 m2 of buried glacier ice in lower Kennar Valley, Quartermain Range. The mapped ice is clean,<10 m thick and covered by a~25 cm sandy drift. The mouth of Kennar Valley is occupied by a lobe of Taylor Glacier, an outlet glacier from Taylor Dome. Based on ice–sediment characteristics, air bubble concentrations and stable isotopic analyses from three ice cores, the lower Kennar Valley ice is glacial in origin. These data coupled with a previously reported exposure age chronology indicate that the buried ice was deposited by a late Pleistocene advance of Taylor Glacier, probably during an interglacial interval. The surface of the buried glacier ice exhibits a patterned ground morphology characterized by small, dome-shaped polygons with deep troughs. This shape possibly reflects the final stages of ice loss, as stagnant, isolated ice pinnacles sublimate in place. This study highlights how polygon morphology can be used to infer the thickness of clean buried ice and its geomorphological stability throughout Antarctica, as well as other in cold, arid landscapes.

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