环渤海湿地沉积物球囊霉素相关土壤蛋白分布特征及其对湿地土壤风化的影响

【研究目的】球囊霉素作为丛枝菌根真菌（AMF）分泌的一种难降解土壤蛋白,广泛分布于陆地生态系统中,是长期碳贮的重要组成。当前鲜有研究涉及其在滨海湿地中的分布。基于此,本文对中国环渤海主要滨海湿地表层沉积物中球囊霉素相关土壤蛋白（GRSP）的空间分布进行表征,探讨不同湿地生境下GRSP分布及其对沉积物风化的指示意义。【研究方法】本文选取辽河三角洲、北大港和黄河三角洲湿地作为研究区,对166个表层样（0~5 cm）和4个柱状样（0~35 cm）的GRSP、粒度以及常量元素进行测定,并计算化学蚀变系数（CIA）。【研究结果】研究区GRSP在空间上的动态变化受植被类型影响显著,范围在0.06~11.31 mg/g,均值为（2.35±0.16） mg/g;沉积物以粉砂质砂和砂为主,CIA值分布范围为44.79~69.59,部分区域达到中等化学风化;CIA与GRSP呈显著相关（R=~0.49,p<0.01）,总体上CIA随GRSP的增加呈现先增加后减少的趋势。【结论】GRSP在滨海湿地沉积物中的分布受到生境差异性的影响,其与CIA的相关性表征AMF及其代谢产物在地质体风化过程中发挥了潜在的生态功能。创新点：揭示了球囊霉素相关土壤蛋白与地质过程的互馈作用;阐明了丛枝菌根真菌潜在的生态功能。     

Physical characterization of aerosol particles during nucleation events

Particle concentrations and size distributions have been measured from different heights inside and above a boreal forest during three BIOFOR campaigns (14 April–22 May 1998, 27 July–21 August 1998 and 20 March–24 April 1999) in Hyytiälä, Finland. Typically, the shape of the background distribution inside the forest exhibited 2 dominant modes: a fine or Aitken mode with a geometric number mean diameter of 44 nm and a mean concentration of 1160 cm⁻³ and an accumulation mode with mean diameter of 154 nm and a mean concentration of 830 cm⁻³. A coarse mode was also present, extending up to sizes of 20 μm having a number concentration of 1.2 cm⁻³, volume mean diameter of 2.0 μm and a geometric standard deviation of 1.9. Aerosol humidity was lower than 50% during the measurements. Particle production was observed on many days, typically occurring in the late morning. Under these periods of new particle production, a nucleation mode was observed to form at diameter of the order of 3 nm and, on most occasions, this mode was observed to grow into Aitken mode sizes over the course of a day. Total concentrations ranged from 410–45 000 cm⁻³, the highest concentrations occurring on particle production days. A clear gradient was observed between particle concentrations encountered below the forest canopy and those above, with significantly lower concentrations occurring within the canopy. Above the canopy, a slight gradient was observed between 18 m and 67 m, with at maximum 5% higher concentration observed at 67 m during the strongest concentration increases.     

Håndværk og mindre industri i centrale byområder

Andersen, Hans T. & Engelstoft, Sten: Håndværk og mindre industri i centrale byområder. Geografisk Tidsskrift 83, 35–42, May 1, 1983.

The paper attempts to elucidate problems related to small manufacturing industries in central urban areas. The last 10 years' development within this type of industry in two medium-sized Danish towns is demonstrated, and their general conditions are analysed.     

A stage 7 marine interglacial record (the Grødeland Interglacial) on Jaeren, southwestern Norway; foraminiferal, stable isotopes and amino acid evidence

Foraminiferal biostratigraphy, stable isotopes and amino-acid diagenesis have been investigated in a 125 m (+ 1 to — 124 m a.s.l.) long core from Jæren, southwestern Norway. Two marine units, the 42 m thick Grødeland Sand and the 8 m thick Sunde Sand, were found between till beds. Based on the biostratigraphic data, nine foraminiferal assemblage zones are defined. The Grødeland Sand shows a development from an ice-proximal glacial environment in the lower part, through an arctic, possibly shallow-water, environment, into a full interglacial open-shelf regime (the Grødeland Interglacial). The Grødeland Interglacial sediments (zone 6 Cassidulina laevigata-Cibicides zone) were deposited at a water depth of 20 m, in an open, high-energy shelf environment with temperature conditions similar to those prevailing in the northern North Sea today. The interglacial sediments are followed by deposits characteristic of an arctic environment which become more ice proximal upwards. Superimposed on the Grødeland Sand is a diamicton interpreted as till. Above the till is the upper marine unit (the Sunde Sand), which in the lower part yielded a shallow-water arctic fauna replaced upwards by an ice-proximal facies. The upper part of the Sunde Sand is barren of foraminifera and is superimposed by an upper till. The Sunde Interstadial is defined as a climatostratigraphic event resulting in deglaciation of western Norway and deposition of the Sunde Sand. Based on amino acid geochronology and inferences from the biostratigraphy, the Grødeland Interglacial is assigned to oxygen-isotope stage 7, whereas the Sunde Interstadial is assigned to the Early Weichselian. Combined with existing data from the North Sea region and the Norwegian Sea, it is concluded that for stage 7, in addition to stages 1 and 5e, there must have been a strong influx of Atlantic water into the Norwegian Sea north of the British Isles. This circulation created a similar north-south gradient in water masses in the North Sea to that which occurred during the Eemian and the Holocene. In the Nordic Seas, however, the stage 7 warm influx was probably restricted to the eastern part of the basin, unlike the later warm periods. This led to the development of fully interglacial conditions in the North Sea region, even though the palaeoceanographic data from the central part of the Nordic Seas suggest relatively cooler conditions for oxygen-isotope stage 7.     

Lipid composition of phytoplankton from the Barents Sea and environmental influences on the distribution pattern of carbon among photosynthetic end products

The colonial algae Phaeocystis pouchetii and Dinobryon pellucidum dominated the phytoplankton crop at three stations in the Polar Front area of the Barents Sea.
Lipid extracted from the seawater containing the phytoplankton was dominated by neutral lipid classes, particularly triacylglycerols, and phospholipids were more abundant than galactolipids at all stations. Polyunsaturated fatty acids comprised between 15 and 26% of fatty acids of total lipid.
Of the carbon assimilated into lipid over 24 hours, 40% was located in the neutral lipid fraction. Phospholipids contained a smaller proportion of fixed carbon than galactolipids.
No defiinte relationships were observed between the distribution of fixed carbon in photosynthetic end products and the temperature or irradiance at which the phytoplankton was incubated. At a constant irradiance of 8.5 μmol m⁻²s⁻¹, the highest proportion of fixed carbon was recovered in protein at 4.5°C, but at −1.5°C most radioactivity was present in low molecular weight compounds. Regardless of incubation conditions, lipid always contained less than 30% of total assimilated carbon.     

Temperature variations recorded in Pinus tabulaeformis tree rings from the southern and northern slopes of the central Qinling Mountains, central China

The Qinling Mountain range constitutes a critical boundary for climate and vegetation distribution in eastern central mainland China owing to its importance as a geographic demarcation line. In this article, cores from 88 Chinese pines ( Pinus tabulaeformis ) from the southern (MW site) and northern (NWT site) slopes of the Qinling Mountains were used to reconstruct seasonal temperature variations. During the calibration period, significant correlations were found between ring width and the mean temperature from prior September to current April of 0.76 at the southern slope, and between ring width and the mean May–July temperature of 0.67 at the northern slope. The subsequent temperature reconstructions span 1760–2005 for the northern site and 1837–2006 for the southern site. Prior to the mid-20th century, low September–April temperatures were, in general, followed by high May–July temperatures, probably reflecting variations in the winter and summer monsoon. However, since the mid-20th century, both records show trends of a more pronounced increase in September–April temperature on the southern slope. The results provide independent support for the interpretation that recent warming is unusual in nature, coinciding with the observed record. The results compare well with tree-ring based reconstructions from the surrounding regions, suggesting regional signals in the Qinling Mountain reconstructions.     

Vegetation patterns, recent pollen deposition and distribution of non-pollen palynomorphs in a polygon mire near Chokurdakh (NE Yakutia, NE Siberia)

Fine-scaled distribution patterns of vegetation and palynomorphs in a polygon mire in NE Siberia were studied in 31 × 31 plots of 1 m² (vegetation) and along a transect at intervals of 1 m (palynomorphs). Pollen and non-pollen-palynomorph contents clearly reflect differences between polygon ridges and centres. For most single pollen types, however, no unambiguous relation with actual plant abundances and distribution exists. High pollen values are restricted to the immediate vicinity of the pollen sources, which is attributed to the low height of the vegetation. For several plant taxa, high pollen values were found to be restricted to particular plant specimens in the population. High values of pollen ascribed to taxa currently absent at the relevant plot show that the sampled mosses contain a pollen signal of several years. Betula exilis produces two morphologically clearly distinct pollen types. The distribution of selected non-pollen palynomorphs correlates to microrelief, moisture regime and/or trophic conditions. The study shows that single palaeo-sections from arctic peatlands should not be over-interpreted with respect to their palaeoecological value. Local vegetation types and site conditions, however, can be accurately reconstructed from the total assemblages and from combined occurrences of specific palynomorph types.