Cold-Tolerance Mechanisms of the Antarctic Nematode Panagrolaimus Davidi

When free of surface water in air or liquid paraffin, the antarctic nematode Panagrolaimus davidi is freezing intolerant but avoids freezing by supercooling. Survival of long-term exposure is enhanced by sub-zero temperatures compared with controls maintained at 99% relative humidity and 15°C. In water the nematodes are seeded by exogenous ice nucleation and a proportion are freezing tolerant. Ice formation appears to be restricted to the pseudocbel. The degree of freezing tolerance is dependent upon the age of the culture and its thermal history. P. davidi is freezing tolerant when exposed to sub-zero temperatures in water and freezing intolerant when free of surface water and able to supercool. These two strategies are not mutually exclusive as they are often thought to be in arthropods.

Download Full-text

Saline Growth Conditions Favour Supercooling and Increase the Freezing Tolerance of Leaves of Barley and Wheat

Zeitschrift für Naturforschung C ◽

10.1515/znc-1992-9-1010 ◽

1992 ◽

Vol 47 (9-10) ◽

pp. 695-700 ◽

Cited By ~ 5

Author(s):

Michael Bender ◽

Ulrich Heber ◽

Karl-Josef Dietz

Keyword(s):

Salt Stress ◽

Freezing Tolerance ◽

Growth Conditions ◽

Ice Nucleation ◽

Ice Formation ◽

Freezing And Thawing ◽

Subzero Temperatures ◽

Cellular Dehydration ◽

Detached Leaves ◽

Leaf Survival

When young plants of barley and wheat grown in hydroponic culture were subjected to salt stress, their freezing tolerance increased with increasing severity of salt stress. Detached leaves from salt-stressed plants also exhibited an increased ability to supercool. Avoidance of ice formation permitted leaf survival at subzero temperatures which were no longer tolerated when ice nucleation resulted in extracellular freezing. The increased freezing tolerance under salt stress is attributed to osmotic adjustment of the plants. Increased cellular solute concentrations decrease the extent of cellular dehydration at freezing temperatures, thereby decreasing mechanical and chemical stresses on biomembranes during freezing and thawing.

Download Full-text

Effect of photochemical ageing on the ice nucleation properties of diesel and wood burning particles

Atmospheric Chemistry and Physics ◽

10.5194/acp-13-761-2013 ◽

2013 ◽

Vol 13 (2) ◽

pp. 761-772 ◽

Cited By ~ 28

Author(s):

C. Chou ◽

Z. A. Kanji ◽

O. Stetzer ◽

T. Tritscher ◽

R. Chirico ◽

...

Keyword(s):

Relative Humidity ◽

Chemical Properties ◽

Diesel Oxidation Catalyst ◽

Ice Nucleation ◽

Oxidation Catalyst ◽

Ice Formation ◽

Diesel Vehicles ◽

Diesel Particles ◽

Wood Burning ◽

Deposition Mode

Abstract. A measurement campaign (IMBALANCE) conducted in 2009 was aimed at characterizing the physical and chemical properties of freshly emitted and photochemically aged combustion particles emitted from a log wood burner and diesel vehicles: a EURO3 Opel Astra with a diesel oxidation catalyst (DOC) but no particle filter and a EURO2 Volkswagen Transporter TDI Syncro without emission aftertreatment. Ice nucleation experiments in the deposition and condensation freezing modes were conducted with the Portable Ice Nucleation Chamber (PINC) at three nominal temperatures, −30 °C, −35 °C and −40 °C. Freshly emitted diesel particles showed ice formation only at −40 °C in the deposition mode at 137% relative humidity with respect to ice (RHi) and 92% relative humidity with respect to water (RHw), and photochemical ageing did not play a role in modifying their ice nucleation behaviour. Only one diesel experiment where α-pinene was added for the ageing process, showed an ice nucleation enhancement at −35 °C. Wood burning particles also act as ice nuclei (IN) at −40 °C in the deposition mode at the same conditions as for diesel particles and photochemical ageing also did not alter the ice formation properties of the wood burning particles. Unlike diesel particles, wood burning particles form ice via condensation freezing at −35 °C whereas no ice nucleation was observed at −30 °C. Photochemical ageing did not affect the ice nucleation ability of the diesel and wood burning particles at the three different temperatures investigated but a broader range of temperatures below −40 °C need to be investigated in order to draw an overall conclusion on the effect of photochemical ageing on deposition/condensation ice nucleation across the entire temperature range relevant to cold clouds.

Download Full-text

Effect of photochemical aging on the ice nucleation properties of diesel and wood burning particles

Atmospheric Chemistry and Physics Discussions ◽

10.5194/acpd-12-14697-2012 ◽

2012 ◽

Vol 12 (6) ◽

pp. 14697-14726 ◽

Cited By ~ 3

Author(s):

C. Chou ◽

O. Stetzer ◽

T. Tritscher ◽

R. Chirico ◽

M. F. Heringa ◽

...

Keyword(s):

Relative Humidity ◽

Diesel Oxidation Catalyst ◽

Ice Nucleation ◽

Oxidation Catalyst ◽

Ice Formation ◽

Nucleation Behavior ◽

Diesel Particles ◽

Wood Burning ◽

Photochemical Aging ◽

Deposition Mode

Abstract. A measurement campaign (IMBALANCE) was conducted in 2009 and aimed at characterizing the physical and chemical properties of freshly emitted and photochemically aged combustion particles emitted from a log wood burner and diesel vehicles: a EURO3 Opel Astra with a diesel oxidation catalyst (DOC) but no particle filter and a EURO2 Volkswagen Transporter TDI Syncro with no emission after-treatment. Ice nucleation experiments in the deposition and condensation freezing modes were conducted with the Portable Ice Nucleation Chamber (PINC) at three nominal temperatures, −30 °C, −35 °C and −40 °C. Freshly emitted diesel particles showed ice formation only at −40 °C in the deposition mode at 137% relative humidity with respect to ice (RHi) and 92% relative humidity with respect to water (RHw), and photochemical aging did not play a role in modifying their ice nucleation behavior. Only one diesel experiment where α-pinene was added, showed an ice nucleation enhancement after the aging at −35 °C. Wood burning particles also act as ice nuclei (IN) at −40 °C in the deposition mode at the same conditions as for diesel particles and photochemical aging did also not alter the ice formation properties of the wood burning particles. Unlike diesel particles, wood burning particles form ice via condensation freezing at −35 °C with no ice nucleation observed at −30 °C for wood burning particles. Photochemical aging did not affect the ice nucleation ability of the diesel and wood burning particles at the three different temperatures investigated but a broader range of temperatures below −30 °C need to be investigated in order to draw an overall conclusion on the effect of photochemical aging on deposition/condensation ice nucleation across the entire temperature range relevant to cold clouds.

Download Full-text

Modelling the Effects of Acid Deposition: Estimation of Long-Term Water Quality Responses in Forested Catchments in Finland

Hydrology Research ◽

10.2166/nh.1988.0008 ◽

1988 ◽

Vol 19 (2) ◽

pp. 99-120 ◽

Cited By ~ 17

Author(s):

A. Lepistö ◽

P. G. Whitehead ◽

C. Neal ◽

B. J. Cosby

Keyword(s):

Water Quality ◽

Surface Water ◽

Base Cations ◽

Surface Water Quality ◽

Mineral Weathering ◽

Co2 Solubility ◽

Forested Catchments ◽

Deposition Rates ◽

Magic Model

A modelling study has been undertaken to investigate long-term changes in surface water quality in two contrasting forested catchments; Yli-Knuutila, with high concentrations of base cations and sulphate, in southern Finland; and organically rich, acid Liuhapuro in eastern Finland. The MAGIC model is based on the assumption that certain chemical processes (anion retention, cation exchange, primary mineral weathering, aluminium dissolution and CO2 solubility) in catchment soils are likely keys to the responses of surface water quality to acidic deposition. The model was applied for the first time to an organically rich catchment with high quantities of humic substances. The historical reconstruction of water quality at Yli-Knuutila indicates that the catchment surface waters have lost about 90 μeq l−1 of alkalinity in 140 years, which is about 60% of their preacidification alkalinity. The model reproduces the declining pH levels of recent decades as indicated by paleoecological analysis. Stream acidity trends are investigated assuming two scenarios for future deposition. Assuming deposition rates are maintained in the future at 1984 levels, the model indicates that stream pH is likely to continue to decline below presently measured levels. A 50% reduction in deposition rates would likely result in an increase in pH and alkalinity of the stream, although not to estimated preacidification levels. Because of the high load of organic acids to the Liuhapuro stream it has been acid before atmospheric pollution; a decline of 0.2 pH-units was estimated with increasing leaching of base cations from the soil despite the partial pH buffering of the system by organic compounds.

Download Full-text

Surface water and groundwater interaction at long-term exploited riverbank filtration site based on groundwater flow modelling (Mosina-Krajkowo, Poland)

Journal of Hydrology Regional Studies ◽

10.1016/j.ejrh.2021.100882 ◽

2021 ◽

Vol 37 ◽

pp. 100882

Author(s):

Magdalena Matusiak ◽

Krzysztof Dragon ◽

Jozef Gorski ◽

Roksana Kruc-Fijałkowska ◽

Jan Przybylek

Keyword(s):

Surface Water ◽

Groundwater Flow ◽

Riverbank Filtration ◽

Flow Modelling ◽

Surface Water And Groundwater ◽

Groundwater Flow Modelling

Download Full-text

Surface Water Temperature Predictions at a Mid-Latitude Reservoir under Long-Term Climate Change Impacts Using a Deep Neural Network Coupled with a Transfer Learning Approach

Water ◽

10.3390/w13081109 ◽

2021 ◽

Vol 13 (8) ◽

pp. 1109

Author(s):

Nobuaki Kimura ◽

Kei Ishida ◽

Daichi Baba

Keyword(s):

Climate Change ◽

Surface Water ◽

Water Temperature ◽

Transfer Learning ◽

Air Temperature ◽

Climate Models ◽

Temporal Variations ◽

Training Data ◽

Surface Water Temperature

Long-term climate change may strongly affect the aquatic environment in mid-latitude water resources. In particular, it can be demonstrated that temporal variations in surface water temperature in a reservoir have strong responses to air temperature. We adopted deep neural networks (DNNs) to understand the long-term relationships between air temperature and surface water temperature, because DNNs can easily deal with nonlinear data, including uncertainties, that are obtained in complicated climate and aquatic systems. In general, DNNs cannot appropriately predict unexperienced data (i.e., out-of-range training data), such as future water temperature. To improve this limitation, our idea is to introduce a transfer learning (TL) approach. The observed data were used to train a DNN-based model. Continuous data (i.e., air temperature) ranging over 150 years to pre-training to climate change, which were obtained from climate models and include a downscaling model, were used to predict past and future surface water temperatures in the reservoir. The results showed that the DNN-based model with the TL approach was able to approximately predict based on the difference between past and future air temperatures. The model suggested that the occurrences in the highest water temperature increased, and the occurrences in the lowest water temperature decreased in the future predictions.

Download Full-text

Mass balance of the Antarctic ice sheet 1992–2016: reconciling results from GRACE gravimetry with ICESat, ERS1/2 and Envisat altimetry

Journal of Glaciology ◽

10.1017/jog.2021.8 ◽

2021 ◽

pp. 1-27

Author(s):

H. Jay Zwally ◽

John W. Robbins ◽

Scott B. Luthcke ◽

Bryant D. Loomis ◽

Frédérique Rémy

Keyword(s):

Mass Balance ◽

Antarctic Peninsula ◽

East Antarctica ◽

Mantle Material ◽

West Antarctica ◽

Mantle Viscosity ◽

Grounding Line ◽

The Antarctic ◽

Total Gain

Abstract GRACE and ICESat Antarctic mass-balance differences are resolved utilizing their dependencies on corrections for changes in mass and volume of the same underlying mantle material forced by ice-loading changes. Modeled gravimetry corrections are 5.22 times altimetry corrections over East Antarctica (EA) and 4.51 times over West Antarctica (WA), with inferred mantle densities 4.75 and 4.11 g cm−3. Derived sensitivities (Sg, Sa) to bedrock motion enable calculation of motion (δB0) needed to equalize GRACE and ICESat mass changes during 2003–08. For EA, δB0 is −2.2 mm a−1 subsidence with mass matching at 150 Gt a−1, inland WA is −3.5 mm a−1 at 66 Gt a−1, and coastal WA is only −0.35 mm a−1 at −95 Gt a−1. WA subsidence is attributed to low mantle viscosity with faster responses to post-LGM deglaciation and to ice growth during Holocene grounding-line readvance. EA subsidence is attributed to Holocene dynamic thickening. With Antarctic Peninsula loss of −26 Gt a−1, the Antarctic total gain is 95 ± 25 Gt a−1 during 2003–08, compared to 144 ± 61 Gt a−1 from ERS1/2 during 1992–2001. Beginning in 2009, large increases in coastal WA dynamic losses overcame long-term EA and inland WA gains bringing Antarctica close to balance at −12 ± 64 Gt a−1 by 2012–16.

Download Full-text