Water, Salt and Heat Influences on Carbon and Nitrogen Dynamics in Seasonally Frozen Soils in Hetao Irrigation District, Inner Mongolia, China

To investigate carbon (C) and nitrogen (N) dynamics in seasonally frozen soils under saline and shallow groundwater supply conditions, in-situ lysimeter experiments with different groundwater table depths (WTD=1.8 and 2.2 m) were conducted in Inner Mongolia, China during the wintertime of 2012-2013. Changes in soil organic C and total N in multiple layers during various periods, as well as their relationships with soil water, salt, and heat dynamics were analyzed. Accumulation of soil organic C and total N during freezing periods was strongly related to water and salt accumulation under temperature and water potential gradients. Water and salt showed direct influences on soil C and N dynamics by transporting them to upper layer and changing soil microbial activity. Salt accumulation in the upper layer during freezing and thawing of soil affected microbial activity by lowering osmotic potential, resulting in lower C/N ratio. Nitrogen in soil tended to be more mobile with water during freezing and thawing than organic C, and the groundwater table also served as a water source for consecutive upward transport of dissolved N and C. The changes in C and N in the upper 10 cm soil layer served as a good sign for identification of water and salt influences on soil microbial activity during freezing/thawing.     

Climatic responses of tree-ring widths of <Emphasis Type="Italic">Larix gmelinii</Emphasis> on contrasting north-facing and south-facing slopes in central Siberia

An analysis was performed on the climatic responses of the radial growth of Larix gmelinii (Rupr.) Rupr. on contrasting north-facing and south-facing slopes in Tura, central Siberia. We developed chronologies of tree-ring width for four plots, designated as north-upper, northlower, south-upper, and south-lower. Both residual and standard chronologies of tree-ring widths exhibited a significant positive correlation with temperature from the end of May until early June in all four plots. The chronologies of ring width did not reveal any major difference in the response to temperature among the four plots. The standard chronologies of ring widths on the north-facing slope were negatively correlated with precipitation during the winter (October–April) and in early and mid-May, whereas the residual chronologies did not reveal clear relationships with precipitation during the winter and May. The significant correlation between ring width and temperature from the end of May until early June indicates that temperatures in springtime play a significant role in the radial growth of L. gmelinii. The negative correlations between standard chronologies of tree-ring width and precipitation in the winter and in May on the north-facing slope indicate that lowfrequency fluctuations in snowfall have negative effects on the radial growth. However, these effects vary and depend on the microscale topography. Part of this report was presented at the 55th Annual Meeting of the Japan Wood Society, March 2005, Kyoto     

南极半岛海洋气候区的土壤Ⅳ.分类问题

本文简要论述了早期南极土壤分类研究工作。对在南极海洋性气候区应用《美国土壤系统分类》和《国际土壤分类参比基础》进行土壤分类工作的最新实践进行了阐述和比较;同时,依照《中国土壤系统分类》对本区进行了初步的分类尝试。研究结果显示,南极海洋性气候区的主要土壤分别属于《美国土壤系统分类》冻土纲下的各级单元。比较而言,其他两个分类系统在本区的应用相对困难。     

Slope sediment yield in arid lowland continuous permafrost environments, Canadian Arctic Archipelago

Surface wash erosion was measured at runoff plots on low to moderate slopes in clayey and sandy silts underlain by continuous permafrost on the Fosheim Peninsula, Ellesmere Island. Due to snow redistribution in winter, total precipitation on the plots varied from 34 to 150 mm, with corresponding surface runoff values of 0 to 102 mm. Where runoff occurred, at least 80% of it was derived from snowmelt. Suspended sediment removal was <75 g m⁻² a⁻¹ at relatively well-vegetated sites but averaged more than 1200 g m⁻² a⁻¹ at a plot where the vegetation had been removed by landsliding. Niveo-aeolian deposition was greater than suspended sediment removal at some plots, indicating net accumulation. Solute removal ranged up to 80 g m⁻² a⁻¹ and exceeded clastic sediment transport at one vegetated site. Elevated rates of erosion at the sites of detachment slides that pre-date 1950 demonstrated that terrain disturbance in permafrost environments can affect slopewash processes for at least several decades.Plot data (precipitation, vegetation and surface grain-size) from the Fosheim Peninsula and Banks Island were used to develop a statistical model of suspended sediment removal by surface wash on undisturbed slopes. For any given grain-size, the model predicts a rise in erosion from zero precipitation (because of an absence of runoff) to a peak at about 50 mm, a decline as precipitation increases to 300 mm and a further increase in erosion beyond this inflection point. This non-linear response is due to the complex interaction of moisture (primarily snow) and vegetation cover. Erosion at any given precipitation value varies through three orders of magnitude depending on surface grain-size. The maximum erosion predicted is 1 kg m⁻² a⁻¹ for a runoff plot with 1100 mm of precipitation, a corresponding vegetation cover of 77% and a median surface grain-size of 7 φ.     

Effects of pretreatment of soil samples on N mineralization in incubation experiments

Summary We studied the effects of pretreating soil samples (field-fresh, drying at 40° and 105°C, freezing/thawing) on N mineralization in an incubation experiment and on the dynamics of the organic N fraction extracted by K₂SO₄ solution. The soil samples were collected from plots in a long-term field experiment with the application of mineral fertilizer and farmyard manure. Compared with the field-fresh soil samples, freezing/thawing resulted in higher NO ₃ ^– -N contents while the NH ₄ ⁺ -N and the organic N content were increased by drying at 105°C. During the incubation period N mineralization was highest after the samples were dried at 105°C and a little lower in those dried at 40°C. After freezing/thawing the order of magnitude of N mineralization remained the same. The difference in organic N between the beginning and the end of the incubation experiment and the mineral N content at the end of the experiment were correlated significantly. Despite this correlation, however, the change in the organic N content underestimated the N mineralization rates.     

挪威北部土壤微生物活性的季节变化

Seasonal development of soil microbial activity and bacterial biomass in sub-polar regions was investigated to determine the impacts of biotic and abiotic factors, such as organic matter content, temperature and moisture. The study was performed during spring thaw from three cultivated meadows and two non-cultivated forest sites near Alta, in northern Norway. Samples from all five sites showed increasing respiration rates directly after the spring thaw with soil respiration activity best related to soil organic matter content. However, distributions of bacteria] biomass showed fewer similarities to these two parameters. This could be explained by variations of litter exploitation through the biomass. Microbial activity started immediately after the thaw while root growth had a longer time lag. An influence of root development on soil microbes was proposed for sites where microorganisms and roots had a tight relationship caused by a more intensive root structure. Also a reduction of microbial activity due to soil compaction in the samples from a wheel track could not be observed under laboratory conditions. New methodological approaches of differential staining for live and dead organisms were applied in order to follow changes within the microbial community. Under laboratory conditions freeze and thaw cycles showed a damaging influence on parts of the soil bacteria. Additionally, different patterns for active vs. non-active bacteria were noticeable after freeze-thaw cycles.     

猪冷冻附睾精子与体外成熟卵母细胞的体外受精

研究了不同解冻温度（39－41℃，58-60℃,69-71℃)和解冻方式（干解冻、湿解冻）对猪冷冻附睾精子解冻后的活力、存活指数以及受精能力的影响。结果表明，采用同一种解冻方式，经高温解冻的精液，虽然解冻后的活力较好，但活力却下降很快，精子的存活时间和存活指数均不如低温解冻的精液。采用同一种解冻温度，湿解冻所需的解冻时间相对短，解冻后精子活力相对低，但存活时间和存活指数相应优于对应的干解冻试验组。经低温解冻的精子，受精能力最强，精子的受精能力与解冻时间呈显著正相关（r=0.91613,P=0.0103).使用改良TCM199培养液，猪受精卵和颗粒细胞单层共培养能发育至早期桑椹胚。     

Composition and origin of underground arthropod fauna in an extrazonal permafrost soil of central Europe

Summary Evaporation cold brings about all-season icing of the soil that covers an aerated talus deposit (Mount Matzen, Carinthia, Austria; about 1100 m above sea level). This extrazonal permafrost area represents a very rare mire type (condensation water mire) as well as a particular sort of underground biotope, a milieu souterrain superficiel. The subterranean fauna is poor in species and is characterized by troglobitic artropods such as the catopid beetle Aphaobius milleri brevicornis, the dipluran Paurocampa n.sp. and the Collembola Onychiurus mildneri and O. vomatscheri. All these species were confirmed in neighbouring caves.The thick talus layer has been accumulated under peri- and postglacial conditions. Today it spreads out over the karstic bedrock and covers the interconnected rock fissures, the source of the subterranean fauna. The Holocene origin of the talus mantle suggests a (sub-)recent colonization of the permafrost interstice by cave-dwelling species.Dedicated to the late Prof. Dr. M.S. Ghilarov     

Electrical Conductivity of Frozen Shrimp and Flounder at Different Temperatures and Voltage Levels

Electrical conductivity (EC) is an important property during ohmic thawing of seafood. EC of frozen flounder, tiger and white shrimp, and shrimp shells at different voltages and temperatures (T) was measured. The materials were homogenized in a blender. PVC tubes (lengths: 4.1 to 5.6 cm, diameter: 1.5 cm) were filled with the material and fitted with circular stainless steel electrodes connected to a DC power supply. The tubes were frozen to constant Ts (-16 to -4°C). Voltage gradient (VL, 8.3 to 122 Volts/cm) and current were measured with multimeters. The calculated specific conductivity (SpC = Siemens/m) depended strongly on temperature. VL had a small effect on SpC. An equation of the form SpC = a + b VL + c exp(d/T + f/T²) was fitted to the data. R² values for shrimp shells, tiger shrimp, and flounder were 0.96, 0.83, and 0.64, respectively.     

液氮保存对南瓜种子生理生化特性的影响

以南瓜种子Pu5004为试材,将含水量从10.39%分别降至9.16%、6.75%和3.24%,液氮(LN2)保存24 h后,运用快速和常温2种方法解冻,测定种子发芽率、活力指数、发芽指数及电导率、过氧化物酶含量等活力指标,探讨液氮保存对南瓜种子活力及生理生化特性的影响.结果表明:影响南瓜种子液氮保存的主要因素是种子含水量;随含水量降低,发芽率、发芽指数、活力指数降低;种子选择透性受到影响,细胞膜修复能力减弱,酶活性降低;解冻方式也是影响液氮保存的一个因素,快速解冻种子活力高.