Sedimentary record of climate change in a high latitude fjord—Kongsfjord

The sedimentary record of climate change in the Arctic region is useful for understanding global warming.Kongsfjord is located in the subpolar region of the Arctic and is a suitable site for studying climate change.Glacier retreat is occurring in this region due to climate change,leading to an increase in meltwater outflow with a high debris content.In August 2017,we collected a sediment Core Z3 from the central fjord near the Yellow River Station.Then,we used the widely used chronology method of 210Pb,^(137)Cs,and other parameters to reflect the climate change record in the sedimentary environment of Kongsfjord.The results showed that after the mid-late 1990s,the mass accumulation rate of this core increased from 0.10 g/(cm^(2)·a)to 0.34 g/(cm^(2)·a),while the flux of^(210)Pb_(ex)increased from 125 Bq/(m^(2)·a)to 316 Bq/(m^(2)·a).The higher sedimentary inventory of^(210)Pb_(ex)in Kongsfjord compared to global fallout might have been caused by sediment focusing,boundary scavenging,and riverine input.Similarities between the inventory of^(137)Cs and global fallout indicated that terrestrial particulate matter was the main source of^(137)Cs in fjord sediments.The sedimentation rate increased after 1997,possibly due to the increased influx of glacial meltwater containing debris.In addition,the^(137)Cs activity,percentage of organic carbon(OC),and OC/total nitrogen concentration ratio showed increasing trends toward the top of the core since 1997,corresponding to a decrease in the mass balance of glaciers in the region.The results ofδ^(13)C,δ^(15)N and OC/TN concentration ratio showed both terrestrial and marine sources contributed to the organic matter in Core Z3.The relative contribution of terrestrial organic matter which was calculated by a two-endmember model showed an increased trend since mid-1990s.All these data indicate that global climate change has a significant impact on Arctic glaciers.

2017年九寨沟MS 7.0级地震震前电离层异常

以2017年8月8日九寨沟发生的MS7.0级地震为背景,利用CODE提供的GIM数据,采用滑动四分位法,研究地震前后电离层的异常现象与地震的关系。通过对震中及周围4个参考点进行TEC异常检测,发现孕震区在2017年7月28日、8月4日和8月6日均出现了不同程度的电离层异常现象。结合日地环境和全球TEC异常分布进一步分析后得出:2017年7月28日和8月6日出现的电离层异常可能是地震前兆,异常区域没有垂直对应于震中,且异常具有共轭结构并表现出向赤道漂移的趋势;而8月4日出现的电离层异常可能由地磁扰动引起。

High-frequency climatic fluctuations over the past 30 ka in northwestern margin of the East Asian monsoon region, China

Whether millennial-to centennial-scale climate variations throughout the Holocene convey universal climate change is still widely debated.In this study,we aimed to obtain a set of high-resolution multi-proxy data(1343 particle size samples,893 total organic carbon samples,and 711 pollen samples)from an alluvial-lacustrine-aeolian sequence based on an improved age-depth model in the northwestern margin of the East Asian monsoon region to explore the dynamics of climate changes over the past 30 ka.Results revealed that the sequence not only documented the major climate events that corresponded well with those reported from the North Atlantic regions but also revealed many marked and high-frequency oscillations at the millennial-and centennial-scale.Specifically,the late stage of the last glacial lasting from 30.1 to 18.1 cal.ka BP was a dry and cold period.The deglacial(18.1-11.5 cal.ka BP)was a wetting(probably also warming)period,and three cold and dry excursions were found in the wetting trend,i.e.,the Oldest Dryas(18.1-15.8 cal.ka BP),the Older Dryas(14.6-13.7 cal.ka BP),and the Younger Dryas(12.5-11.5 cal.ka BP).The Holocene can be divided into three portions:the warmest and wettest early portion from 11.5 to 6.7 cal.ka BP,the dramatically cold and dry middle portion from 6.7 to 3.0 cal.ka BP,and the coldest and driest late portion since 3.0 cal.ka BP.Wavelet analysis results on the total pollen concentration revealed five substantially periodicities:c.5500,2200,900,380,and 210 a.With the exception of the c.5500 a quasi-cycle that was causally associated with the Atlantic meridional overturning circulation,the other four quasi-cycles(i.e.,c.2200,900,380,and 210 a)were found to be indirectly causally associated with solar activities.This study provides considerable insight into the dynamic mechanism of the Asian climate on a long-time scale and future climatic change.

Effects of 5-Aminolevulinic Acid (ALA) on Zinnia hybrida Growth and Phytoremediation Effects in Oil-Contaminated Soil

In this study, we compared plant height, weight, soil TPH concentration, and soil DHA level after 18 weeks of Zennia hybrida cultivation with four different concentrations of 5-Aminolevulinic acid (ALA)-based liquid fertilizer: 1500-fold, 5000-fold, and 8000-fold dilutions, along with a non-treatment control of diluted ALA. The plants of ALA-treated were significantly taller than the non-treatment control. The plants of ALA-treated plants were higher in shoot fresh weight, shoot dry weight, and root dry weight than the non-treatment control. The plot of ALA-based liquid fertilizer with the 5000-fold dilution was significantly highest in shoot fresh weight, shoot dry weight, and root dry weight. ALA-treated plants were lower in the soil Total Petroleum Hydrocarbon (TPH) concentration than the non-treatment control. The plot of ALA-based liquid fertilizer with the 5000-fold was significantly lowest in the TPH concentration. In addition, ALA-treated plants were higher in the soil dehydrogenase activity (DHA) than the non-treatment control. The plot of ALA-based liquid fertilizer with the 5000-fold was significantly highest in the TPH concentration. This study indicated that ALA-applied zinnia-grown oil-contaminated soil is more effective than not. The remediation in oil-contaminated soil with ALA-based liquid fertilizer is more effective than the non-treatment control;furthermore, ALA application with 5000-fold dilution was most suitable in oil-contaminated soil among other plots.

TOTAL PHOSPHORUS RELEASE FROM BOTTOM SEDIMENTS IN FLOWING WATER

In this paper, the bottom of the Dianshan Lake was selected as a test sample. The dynamic release of contaminated sediments into the overlying water column was experimentally investigated in an open water channel under different hydrodynamic conditions. The experimental results indicate that the Total Phosphorus （TP） release process can be divided into three stages： rapid release, slow release and equilibration release. In the initial release stage the measured TP concentration changes along the depth. The TP concentration near the sediment-water interface is higher than that near the water surface, but the TP concentration becomes uniform along the depth after 3 h. The dynamic release of re-suspension sediment pollutants is about 6 times higher than the static release of sediment-water interface. There are three main types of release mechanism： diffusion release, re-suspended pore water mixing release and re-suspended particles desorbing release.

Biochar reduces uptake and accumulation of polycyclic aromatic hydrocarbons(PAHs) in winter wheat on a PAH-contaminated soil

For years, biochar has been successfully used for the remediation of polycyclic aromatic hydrocarbons(PAHs) in contaminated soils, not only for improving their removal from soil but also for reducing their uptake by crops. However, the underlying mechanism of biochar application reducing PAH uptake and accumulation in winter wheat remains unclear. Pot trials were conducted on a PAH-contaminated soil amended with bamboo biochar, coconut shell biochar,and maize straw biochar(MSB) for an entire growth period of winter wheat. Compared with no biochar control(CK), application of the three types of biochar significantly(P < 0.01) reduced grain PAH concentration, total equivalent concentration(TEC), and incremental lifetime cancer risk(ILCR), indicating that biochar application, especially MSB, reduced the risk of exposure to PAHs in wheat grain. Furthermore, all three types of biochar significantly(P < 0.05)reduced PAH uptake and accumulation in wheat roots and stems, probably because biochar application enhanced the degradation of PAHs in the rhizosphere soil. Compared with CK, application of the three types of biochar significantly(P < 0.05) reduced the concentration of PAHs in the rhizosphere soil by15.9%–33.7%. It was found that the degradation rate of high-molecular-weight(HMW) PAHs(5-and 6-ring PAHs) was significantly(P < 0.05) higher than that of low-molecular-weight(LMW) PAHs(2–4-ring PAHs) regardless of the type of biochar used. Additionally, all three types of biochar significantly increased the relative abundance of the dominant bacterial phyla and genera in soil. Redundancy and correlation analyses also showed that there was a strong correlation between the removal rate of PAHs and dominant bacteria in the rhizosphere soil. This study indicated that biochar effectively reduced the health risk from dietary exposure to PAHs in wheat grains by increasing the abundance of bacteria related to PAH degradation, promoting the biodegradation of PAHs in the rhizosphere soil, and consequently reducing PAH uptake by wheat.