Palynological Evidence of Late Pleistocene Soft-sediment Deformation Event in the Northeastern Margin of the Tibetan Plateau

The northeastern margin of the Tibetan Plateau is the youngest part of the Tibetan Plateau where tectonic activity is intense and climate change is complex.In this study,combined with field investigations,we explored accelerator mass spectrometry 14C and optically stimulated luminescence dating and palynological analysis of the sedimentary sequence in the Qingshuihe Basin to explain the origin of soft-sediment deformation layer.Dating and palynological results from the Sanchahe section in the basin revealed a detailed history of vegetation variation and associated climate change from~18 to~5 ka BP.The results indicate that the permafrost developed at~18–11.7 ka BP,and the soft-sediment deformation structures formed at~11.7–5 ka BP.Together with the characteristics of the deformation(meter-scale,continuous symmetrical wave)and paleoclimate,we suggest that the soft-sediment deformation layer in the late Pleistocene was cryoturbated under climatic conditions.The discovery of a series of cryoturbations in the Qingshuihe Basin has further enriched the regional distribution of periglacial phenomena in the west of the Ordos Plateau,expanded the distribution range of periglacial phenomena,and provided evidence for exploring the temporal and spatial changes in permafrost in northern China at the end of the late Pleistocene.

Physico-Chemical Profile of Four Types of Honey from the South of the Republic of Moldova

There are many studies that compare the quality and biological characteristics of honey with distinct geographical and botanical origins. However, the physico-chemical and biological properties of different types of honey in the same production regions are rarely mentioned. The honey used in this study: sunflower honey, rapeseed honey, manna honey and polyflora honey, came from GT “Malai C” in Taraclia village, Causeni district in the southern part of the Republic of Moldova and belonged to the flowering season of year 2020. Following the polynecological analysis, it was found that two types of honey are monofloral with a dominant pollen content of Helianthus spp. (49.15% - 93.12%) in sunflower honey and Brassica spp. (52.17% - 70.11%) in rapeseed honey. Mana honey and polyflora contain several types of pollen. Thus, four types were identified in manna honey, including: Acer platanoides (29.11% - 30.11%), Quercus robur (28.67% - 29.99%), Rubus idaeus (21.55% - 28.78%), Taraxacum officinale (22.21% - 28.76%). Polyflora honey contains: Helianthus annuus (24.91% - 31.11%), Brassica napus (23.45% - 29.18%), Tilia (28.95% - 31.92%). Based on a Pfund scale, it was found that the color of the honey varied from a lighter shade for rapeseed honey (water amber 7.66 ± 3.002 mm) to a darker color for sunflower honey and polyflora (extra light amber 34.366 ± 21.01 mm and 36.04 ± 1.115 mm respectively). Spectrophotometric determination of phenolic compounds in honey samples showed that their content ranged from 38.18 mg GAE/kg honey for rapeseed honey to 831.09 mg GAE/kg honey for manna honey. At the same time, the flavonoid content ranged from 28.41 mg QUE/kg honey for rapeseed honey to 151.72 mg QUE/kg honey for manna honey. Mana honey showed a better antioxidant activity than the other honey samples in the study (72.03%). The reported results suggest that manna honey has the best potential and its consumption in the human diet as food with valuable biological properties can be encouraged, despite the fact that in the Republic of Moldova it is in a small amount.

Zea mays L. Pollen： An Approach to Its Quality Control

Zea mays L. is one of the biggest cropping systems among the sustainable development agronomy. Pollen from this crop source is unexplored and apiculture can be a good partner adding value to the product and creating new jobs helping to solve some social issues as unemployment. However, food safety is crucial, thus the aim of this study was to explore the flavonoid/phenolic profiles from Z. mays L. pollen as a fingerprint for this plant identification and also to demonstrate how the method of bee pollen samples （honeybee collected pollen） is applied. For this purpose, several sources ofZ. mays L. pollen were analyzed, including corn hybrids and genetic modified samples collected at the breeding fields. For this work, samples were taken at several years from 2000 to 2012 and collected from different countries and locations, such as Portugal, Mexico and Brazil. Results showed, for the first time, that the fingerprint （flavonoid/phenolic profile） for Z. mays L. pollen does not change over the time of sampling neither with the region of harvesting. The high performance liquid chromatography-diode array detector （HPLC/DAD） fingerprints of phenolic/flavonoid extract from Z. mays remain unchanged for all samples analyzed from different countries, hybrids and/or genetic modified plants. This is also the first study reporting these phenolic compounds not only in pollen collected directly from hybrid plants, but also in Z. mays bee pollen. The described fingerprinting method is easy, fast and accurate for the characterization of Z. mays L. pollen samples and complete microscopic analysis because it is species-specific.