Oxidative degradation of model lipids representative for main paper pulp lipophilic extractives by the laccase–mediator system

Different model lipids-alkanes, fatty alcohols, fatty acids, resin acids, free sterols, sterol esters, and triglycerides-were treated with Pycnoporus cinnabarinus laccase in the presence of 1-hydroxybenzotriazole as mediator, and the products were analyzed by gas chromatography. The laccase alone decreased the concentration of some unsaturated lipids. However, the most extensive lipid modification was obtained with the laccase-mediator system. Unsaturated lipids were largely oxidized and the dominant products detected were epoxy and hydroxy fatty acids from fatty acids and free and esterified 7-ketosterols and steroid ketones from sterols and sterol esters. The former compounds suggested unsaturated lipid attack via the corresponding hydroperoxides. The enzymatic reaction on sterol esters largely depended on the nature of the fatty acyl moiety, i.e., oxidation of saturated fatty acid esters started at the sterol moiety, whereas the initial attack of unsaturated fatty acid esters was produced on the fatty acid double bonds. In contrast, saturated lipids were not modified, although some of them decreased when the laccase-mediator reactions were carried out in the presence of unsaturated lipids suggesting participation of lipid peroxidation radicals. These results are discussed in the context of enzymatic control of pitch to explain the removal of lipid mixtures during laccase-mediator treatment of different pulp types.     

Calcium carbonate deposits reduce predation pressure on Gammarus fossarum from salamander larvae

• 1 We studied the lime deposits on Gammarus fossarum from a tufa brook in Southern Germany. Between 20 and 75% of the gammarids collected carried calcium carbonate deposits at the dorsal part of the pleon segments. Average weight of deposits ranged between 0.6 mg on small and 1.7 mg on large specimens and constituted 60–20% of specimens' dry weights.
• 2 Predator‐prey experiments with salamander larvae and gammarids showed that significantly fewer prey with deposits were eaten than without deposits and that the differences in predation risks between prey with vs. prey without deposits were greatest in small and medium sized specimens.
• 3 Lime deposits changed the feel or taste and the activity patterns of gammarids. Gammarids with deposits were rejected significantly more often by the predators than gammarids without deposits. Medium sized specimens with deposits, which suffered a great predation risk, were significantly less active than specimens of the same size category without deposits.
• 4 Lime deposits did not increase conspicousness or decrease escape ability of prey. Prey with deposits were attacked by predators with the same frequency and captured with the same success as prey without deposits.
• 5 Lime deposits may afford effective protection from salamander predation in some natural habitats. Predation impact on gammarids by salamander larvae may be low, however, because larval density was very low in most places (< 1 m^‐2) and because larvae are only present for a limited time until they start metamorphosis.

     

Eridites undulatum壳体微细构造

利用偏光显微镜及扫描电子显微镜观察了假直角石类Ｅｒｉｄｉｔｅｓｕｎｄｕｌａｔｕｍ的体管沉积及气室沉积微细构造特征,体管沉积内部有机质层及矿物晶体层形态及厚度较稳定。气室沉积中有机质层及矿物晶体层形态及厚度变化大,晶体层内部具有柱状晶体。基于内部微细构造特征,推测体管沉积由软体上皮细胞直接分泌而成,气室沉积由体液渗透连接环在气室内表面上形成矿化基质后通过有机质层及矿物晶体层不断加积而成。另外,通过与石炭纪其它假直角石类内部沉积微细构造特征的比较,认为假直角石类内部沉积的微细构造特征不具有分类学意义。     

Sedimentary features and the evolution of lake Honghu,central China

Palaeolimnological studies of the sediments of Honghu, a large shallow lake in Central China, were used to investigate the history of the origin, formation, and changing extent of the lake. The results indicate that Honghu is a naturally-dammed feature, formed about 3000 years ago by meandering of the Changjiang river. Lake level then fell in the period after 2500 BP, but during the Jin epoch (265–420 AD) it recovered, only to fall once more after the Song dynasty (969–1279 AD). The most recent episodes of reflooding are dated to ca. 400 years ago, and to the late nineteenth century.     

The moult cycle of the terrestrial isopod Armadillo officinalis Duméril, 1816 (Crustacea: Isopoda: Oniscidea)

The present work focuses on the moult cycle of Armadillo officinalis. For a 100‐day period, 134 animals were observed and routinely examined with the aim of detecting distinctive morphological characters in the several stages and substages of the moult cycle and of disclosing their duration. Statistical tests and Poisson regression models with robust standard errors were used to investigate differences and relationships between moult and the size and gender of the animals. The appearance of the calcium carbonate deposits on the pereon sternites during the premoult stage was documented in detail, and three main substages were identified. The average duration of the premoult and of the biphasic ecdysis was about 12 and 1.5 days, respectively. This observation period, however, did not allow to establish a determined average duration of the intermoult stage, which was extremely variable. This stage lasted for 2 months or more in most of the cases observed, but about 1‐month‐long intermoult stages were also recorded. No statistically significant association was found between the number of moults and gender and size of the animals.     

Benthobservatory studies of micro-flora in a Newfoundland stream.

Collections of algae growing on the windows of a benthobservatory were made between April 1974 and October 1974. Eighty-eight species of algae representing eight classes were identified. Of these, 64% were green algae, 19% were diatoms, 11% were bluegreen algae and 6% were of the remaining 4 classes. The peak of algal growth was noted near mid-July with some indications of early spring and late autumn peaks. The relationship of algal growth to the distribution of some benthic fauna is briefly discussed.     

东秦岭卢氏盆地新发现的旧石器

2019年6-8月,在秦岭东部南洛河流域河南卢氏盆地开展古人类和旧石器考古遗址调查,在南洛河不同阶地之上的黄土堆积地层中新发现旧石器地点27处,采集石制品123件。部分石制品采自于阶地顶部暴露的黄土地层剖面上。石制品包括石核、石片、断块、碎屑、石器等类型,整体属于简单的石核-石片工业。原料为取自河滩砾石堆积的石英、砂岩和石英岩等。石核为简单剥片的单台面石核和转向剥片石核。石器组合中既有手镐、砍砸器等重型类型,也有以石片为毛坯的中小型刮削器等。根据黄土-古土壤地层序列初步判断,多数地点的石制品出自黄土L1-S2地层堆积,年代范围涵盖中更新世晚期至晚更新世;西庄村南（19LS35）和九寨山（19LS27）两个地点的2件石制品则出自更早的S9和S13古土壤地层堆积中,它们的发现为进一步探寻南洛河流域最早的古人类活动提供了关键性的考古学证据。本次调查扩大了卢氏盆地旧石器时代遗存的时空分布范围,为本区域旧石器遗址的保护和制订研究计划提供了更为全面的依据。     

C3/C4 vegetation evolution over the last 7.0 Myr in the Chinese Loess Plateau: evidence from pedogenic carbonate δC

The stable carbon and oxygen isotopic compositions of soil carbonate were measured on an eolian loess and red clay sequence at Lingtai, the Chinese Loess Plateau. This sequence is composed of 130 m of Tertiary red clay deposits with a basal age of 7.05 Ma overlain by 175 m of Pleistocene loess. In the field we identified ca. 110 carbonate nodule horizons in the red clay and 27 nodule horizons in the loess. These carbonate nodule horizons are formed by leaching and re-precipitation of carbonate from the eolian material. The δ¹³C record of soil carbonate indicates a major expansion of C₄ plants at ca. 4.0 Myr in the Loess Plateau. This event is comparable in timing with the expansion of C₄ plants in northern North America (Cerling et al., 1997. Nature 389, 153–158) but is ca. 3 million years later than the C₄ biomass expansion in Pakistan (Quade et al., 1989. Nature 342, 163–166). The pedogenic characteristics of the soils and the δ¹⁸O record in the red clay suggest that the C₄ plant expansion in the Loess Plateau was not driven by local climatic changes, which may support Cerling et al.'s (1997) assertion that the decline of atmospheric CO₂ levels in the Neogene is responsible for this global vegetation change. Our record also implies that the Tibetan Plateau could have been uplifted to a critical height in the late Miocene, thus resulting in the formation of the atmospheric Great East-Asia Trough.     

Filament lumachelle on top of Middle Jurassic oolite limestones: event deposits marking the drowning of a Tethysian carbonate platform (Subbetic,southern Spain)

Bioclastic accumulations often occur on top of Tethysian carbonate platforms and crinoids are a common constituent of these bioclastic deposits on Lower and Middle Liassic carbonate platforms. In contrast, the relevant literature contains few examples in which the main constituent of the lumachels is thin-shelled bivalves (filaments). This paper presents a study of a filament lumachelle cropping out on top of a Middle Jurassic carbonate platform. The carbonate platform is represented by the Jabalcuz Formation, found in one of the northernmost Subbetic units (south of Jaén city). The lumachelle marks the demise of the carbonate platform and has special features that characterize the drowning phase. This process has been related with the syn-rift extensional tectonics associated to the opening of the Tethys westwards. Stratigraphically, the lumachelle occurs on top of shallow-water oolite limestones (Middle Jurassic) and is overlain by radiolarian-rich pelagic and resedimented deposits (Latest Callovian–Oxfordian). It occurs as a body (about 1.5 km wide and up to 8 m thick) made up entirely of densely packed thin bivalve shells. A remarkable feature of the bivalve shell beds is stromatolite-like crumpled lamination at the outcrop. The observations made at the outcrop scale, by microscope under transmitted light, and by cathodoluminiscence favor a diagenetic origin for this striking structure. Other hypotheses, such as its possible relation with seismicity, cannot be confirmed. The filaments would have filled one of the former basins that originated in relation with syn-rift fault-block tectonics leading to the demise of the carbonate platform. Tectonics was one of the main factors setting in motion a carbonate productivity crisis and the inhibition of a diverse benthic community. Once production failed in the carbonate factory, storms and probably hurricanes as well, swept shell deposits from the shallowest areas of the shallow-water carbonate platform and accumulated them in a coevally formed small half-graben basin. At least three main depositional stages can be differentiated in the fill of this half-graben basin, which was a sediment trap for the accumulation and preservation of the tiny bivalve shells against ebb surges. The massive accumulation of valves, the shortage of micrite around the filaments, outcrop morphology and facies relationships, along with regional geology, are among the arguments supporting this interpretation.     

Chemical Fractionation and Soil-to-Plant Transfer Characteristics of Heavy Metals in a Sludge Deposit Field of the River Ruhr,Germany

The presented study assessed the heavy metal contamination risk in a former sludge deposit field of the River Ruhr in Essen, Germany. Therefore, the temporal and spatial distribution in soils and plants, chemical fractionation, mobilization potential, and transfer characteristics have been investigated. Soil samples, roots and shoots of rushes (Juncus sp.), and stem wood disks of willows (Salix sp.) were analyzed for Zn, Cu, Pb, Ni, Cr, and Cd. Plant available and mobile heavy metal portions have been determined using a sequential extraction procedure. The results show that the soils and the rushes are highly contaminated, although there is a considerable decrease compared to initial concentrations some 20 years ago. The willows show only small heavy metal enrichment. pH induced mobilization potential in soil is high for Cd, Zn and Ni. Additionally, these elements contain high portions of plant-available fractions. High transfer rates from soil to roots and very high rates from roots to shoots of rushes have been determined for Cd and Zn, indicating an accumulation of these elements in shoots of rushes. The rushes reflect the temporal and spatial heavy metal distribution in soil and might thus be used as a bioindicator or for phytoremediation.