[Distribution Characteristics and Influencing Factors of Germanium in Soil in the Eastern Mountainous Area of the Nanyang Basin].

Based on the land quality geochemical survey results in the southwest cultivated area of Nanyang Basin, the content, spatial distribution, and enrichment characteristics of Ge in surface soil (0-20 cm) and deep soil (150-200 cm) in the eastern mountainous area of Nanyang Basin were studied, and the influencing factors of Ge in the surface soil were analyzed. The results showed that the average ω(Ge) in the surface soil and deep soil were 1.39 mg·kg-1 and 1.45 mg·kg-1, respectively. In the study area, 32.22% of surface soil and 12.77% of surface soil was rich in Ge, and the rich areas of the surface soil Ge were mainly distributed in the metamorphic rock and granite-dominant development areas. The optimal theoretical model of surface soil Ge variogram in the study area was a spherical model, and the nugget effect value was 0.434, indicating that surface soil Ge had moderate spatial correlation due to the joint influence of random factors and structural factors. The enrichment factor showed that 93.61% of Ge sites in the topsoil were mainly affected by natural factors, whereas 6.39% of Ge sites were significantly affected by human factors. The source of Ge in soil in the study area was mainly affected by the parent materials of soil formation, but the enrichment of Ge in surface soil was mainly affected by the Fe, Mn oxides, quartz, and pH in the soil.

[Distribution Characteristics and Ecological Risk Assessment of Soil Heavy Metals in the Eastern Mountainous Area of the Nanyang Basin].

The spatial distribution, pollution degree, and ecological risk of heavy metals in the soil were studied by analyzing the contents of As, Hg, Cd, Cr, Pb, Zn, Ni, and Cu and pH values in surface soil samples of the eastern mountainous area of the Nanyang basin. The results showed that the contents of Cd, Cu, Cr, Ni, Pb, Zn, and As in the soil exceeded the screening value of soil pollution risk. The spatial distribution of soil heavy metals displayed regional-and island-shaped. The highest concentration of heavy metals was found in the south of the study area, where a mining area is located. Most of the samples had no pollution levels except some samples with high contents of Cd. For As, Cr, Pb, Zn, Ni, and Cu, the potential ecological risk of most samples were low, while Cd and Hg posed medium risk in most areas. The areas with high and relatively high ecological risk index accounted for 58.93% and 37.66%, respectively. Soil Hg, Cd, and Pb contents were related to anthropogenic activities such mineral mining. As derives from geological processes, while Zn, Ni, Cr, and Cu are both controlled by anthropogenic activities and geological processes. The mining of mineral resources is the main driving factor of soil heavy metal pollution and ecological risk in the study area.

Quaternary stratigraphy and paleoenvironmental evolution of the Ningbo Coastal Plain revealed by core Z02.

The Quaternary sediment in the Ningbo Coastal Plain was the deposit due to sea-land interaction, which recorded information of past climate changes. The region is therefore an ideal area to study paleoclimate changes and sedimentary characteristics. We determined the stratigraphic division and paleoenvironmental evolution based on 14C and paleomagnetic dating, along with detailed analyses of lithology, pollen assemblage, foraminifera and ostracodes assemblage, and grain size of sediment in core Z02 located in the southeastern Ningbo Coastal Plain. The results showed that the boundary between the Holocene and Upper Pleistocene in the core Z02 record was at 30.5 m, the boundary between the Upper and Middle Pleistocene was at 82.65 m, and the boundary between the Quaternary and Lower Cretaceous was at 90 m. The Middle Pleistocene section of the core contained few sediments, while the Lower Pleistocene section was completely missed. During the late Pleistocene, the hydrodynamic conditions experienced energy levels of medium to medium low to medium, and sedimentary facies changed from alluvial lake to overbank to river to lake to alluvial lake to lake to overbank. During the Holocene, the hydrodynamic changes experienced energy levels of medium low to low to medium, and the sedimentary facies changed from shoreland to shallow sea to shoreland lake. The Ningbo Coastal Plain had experienced tectonic uplift, weathering and erosion stage in the Early and Middle Pleistocene, from warm and humid to dry in the Late Pleistocene, and from warm and humid to dry and cool in the Holocene, as revealed by the core Z02 record. This study provided useful information in investigating past environmental changes in the subtropical coastal region of eastern China.

Changes in vegetation and environment in the Betula microphylla wetland of Ebinur Lake in Xinjiang, China since 3900 cal. aBP.

Based on the high resolution record of fossil pollen data from a 190 cm sediment profile collected in a Betula microphylla-dominated wetland of Ebinur Lake in Xinjiang, we aimed to reveal the changes of vegetation and environment in this wetland over the past 3900 years. Results showed that, in the period between 3420 cal. aBP and 3940 cal. aBP, this area was a desert landscape dominated by plants from Chenopodiaceae and Artemisia. During the period of 2830-3420 cal. aBP, this area became a desert steppe dominated by Thelypteris palustris, surrounded by desert plants mainly composed of Chenopodiaceae and Artemisia. In the period between 2640 and 2830 cal. aBP, Typha pollen increased and occupied a dominant position. The area thus became a typical desert intrazonal wetland mainly composed of Typha. In the period between 1200 and 2640 cal. aBP, Phragmites australis began to grow vigorously and became the dominant species. In the period between 660 and 1200 cal. aBP, the population of Betula expanded rapidly, and P. australis plants continued to grow. During the period of 340-660 cal. aBP, the population of B. microphylla became the dominant species, and the abundance of P. australis decreased. However, there was still some P. australis wetlands in the area. Over the past 340 years, as the area of wetlands decreased and the surface water gradually declined, B. microphylla had grown on swampy meadow soils with suitable moisture conditions. In the past 200 years especially, the sharp increases of Chenopodiaceae pollen in palynological assemblage was closely related to the enhancement of human activities and climate change, resulting in the degradation of wetlands and endangerment of B. microphylla. Therefore, it is necessary to strengthen the protection of wetlands and endangered species in this area.

Position and orientation of the westerly jet determined Holocene rainfall patterns in China.

Proxy-based reconstructions and modeling of Holocene spatiotemporal precipitation patterns for China and Mongolia have hitherto yielded contradictory results indicating that the basic mechanisms behind the East Asian Summer Monsoon and its interaction with the westerly jet stream remain poorly understood. We present quantitative reconstructions of Holocene precipitation derived from 101 fossil pollen records and analyse them with the help of a minimal empirical model. We show that the westerly jet-stream axis shifted gradually southward and became less tilted since the middle Holocene. This was tracked by the summer monsoon rain band resulting in an early-Holocene precipitation maximum over most of western China, a mid-Holocene maximum in north-central and northeastern China, and a late-Holocene maximum in southeastern China. Our results suggest that a correct simulation of the orientation and position of the westerly jet stream is crucial to the reliable prediction of precipitation patterns in China and Mongolia.

Surface Pollen Distribution from Alpine Vegetation in Eastern Tibet, China.

We explore the relationship between modern pollen spectra and vegetation patterns in the Eastern Tibet, China in order to provide information on the representation of pollen taxa and improve the general knowledge of vertical pollen transport. Forty-two modern pollen samples collected in surface soil along two altitudinal transects allowed conclusions on vertical pollen dispersal from the alpine region of Dingqing County, Changdu district in Tibet. Discriminant analyses and detrended correspondence analysis (DCA) of 24 pollen taxa were used to further discuss the difference of modern pollen spectra in these alpine vegetation zones. The surface pollen assemblage is divided into three pollen zones, such as subalpine shrub meadow, montane coniferous forest and shrub steppe with sparse trees. Altitude and precipitation are two primary factors contributing to changes in surface pollen assemblage from alpine vegetation in the eastern Tibet. Large amounts of spruce pollen at higher elevations above the timberline might be introduced from lower elevations by upslope winds. Therefore, the interpretation of spruce pollen in the fossil record must take into account long distance upward wind transport. Moreover, the destruction of coniferous forest in the study area is well illustrated in the modern pollen rain.