Hg Vertical Transference in Soil Water System *1

Hg vertical transference in soil water system was studied by analyzing Hg vertical distribution in soil column after adding Hg and one of the two leacheates, deionized water or acid rain, into soil column. The results indicated that Hg was hardly transferable in purple soil. About 86%～88% of the total soil Hg was distributed in the top layer (0～2 cm) and no Hg was detected in the leakage when the purple soil column was leached by deionized water and simulated acid rain. But Hg was more movable in yellow soil with only about 20%～22% of the total soil Hg distributed in the top layer (0～2 cm), and about 17%～25% washed out from the soil column by deionized water and simulated acid rain. Increment in soil bulk density could reduce Hg leaching, thus the more the Hg kept in soil, the less the Hg leached into underground water. Deionized water and acid rain almost played the same role in leaching Hg. Bentonite was most efficient in preventing Hg from vertical transferring in the soil column.

Geomagnetic vertical transfer function revealed from multi-interval geomagnetic data

The geomagnetic vertical transfer functions(VTFs)are useful to constrain the conductivity structure in the deep Earth.In this study,we propose an approach of estimating the geomagnetic VTFs in the wide:period range from the multi-interval geomagnetic data.Applying the above method to the different interval(such as one-second,one-minute,one-hour)data from some geomagnetic observatories in China,we obtain the corresponding VTFs in the wide period range from 64 s to 9,830,400 s.In order to evaluate the possible ocean effect on different observatories,we make close investigations of the real geomagnetic induction vectors at QZH,SYG and XIC observatories.The results indicate that the ocean effect is clear at the coastal observatory like QZH.However,the ocean effect tends to decrease for the inland observatories(such as SYG and XIC)with the increasing distance from the coast.

A Study on Vertical Spatial Transfer of Cultivated Land in Yunnan Province from 1986 to 2008

Based upon ArCGIS,the vertical spatial transfer law of cultivated land in Yunnan was studied through referring to three periods of remote sensing data of Land-Use and Land-Cover Change（LUCC） in Yunnan in 1986,1995 and 2000,Digital Elevation Model（DEM） of Yunnan Province and LUCC data in Yunnan from 2000 to 2008.The main factors that promote vertical spatial transfer law of cultivated land were analyzed by using SPSS,and the influence of policies and government acts upon the change of cultivated land was clarified.The findings indicated that for Yunnan cultivated land there is a trend that in the vertical direction steep slope areas and gentle slope areas divert into mid-slope areas.The primary factor influencing the vertical spatial transfer of cultivated land was policies and government acts.Also,the gradient of ground,total population and number of agriculture employed persons were also main factors in influencing the change of cultivated land,whose influence was obviously below policies and government acts.

Controlled Vertical Transfer of Individual Au Atoms Using a Surface Supported Carbon Radical for Atomically Precise Manufacturing

To explore a proof-of-concept for atomically precise manufacturing(APM)using scanning probe microscopy(SPM),first principle theoretical calculations of atom-by-atom transfer from the apex of an SPM tip to an individual radical on a surfacebound organic molecule have been performed.Atom transfer is achieved by spatially controlled motion of a gold terminated tip to the radical.Two molecular tools for SPM-based APM have been designed and investigated,each comprising an adamantane core,a radical end group,and trithiol linkers to enable strong chemisorption on the Au(111)surface:ethynyl-adamantanetrithiol and adamantyl-trithiol.We demonstrate the details of controlled Au atom abstraction during tip approach toward and retraction from the radical species.Upon approach of the tip,the apical Au atom undergoes a transfer toward the carbon radical at a clearly defined threshold separation.This atomic displacement is accompanied by a net energy gain of the system in the range−0.5 to−1.5 eV,depending on the radical structure.In the case of a triangular pyramidal apex model,two tip configurations are possible after the tip atom displacement:(1)an Au atom is abstracted from the tip and bound to the C radical,not bound to the tip base anymore,and(2)apical tip atoms rearrange to form a continuous neck between the tip and radical.In the second case,subsequent tip retraction leads to the same final configuration as the first,with the abstracted Au atom bound to radical carbon atom of the molecular tool.For the less reactive adamantyl-trithiol radical molecular tool,Au atom transfer is less energetically favored,but this has the advantage of avoiding other apex gold atoms from rearrangement.

The distribution characteristics of short period geomagnetic variations in Shaanxi region

In order to investigate the characteristics of short period geomagnetic variations in Shaanxi region, a temporary measurement profile from Shiquan in the southern part of Shaanxi to Ningxian in Gansu was set up in September of 1996 to carry out simultaneous observation of three component geomagnetic variations along the profile. The vertical transfer functions, the horizontal transfer functions and the spectral component′s relationship of each period segment at each site in the period range from 3 min to 2 h were statistically calculated. Random data theory was applied to the data processing for reference, which led to a relatively good result. Analysis of the data point out that short period geomagnetic variations are affected by the regional influence of underground anomalous inductive current concentration between Wugong and Qianling in the nearly E W direction and by the influence of local inductive current in nearby area of measurement site. The main distribution feature is that vertical transfer functions reverse between Wugong and Qianling and frequency responses of the transfer functions have maximum at period about 20 min.

Horizontal and vertical gene transfer drive sediment antibiotic resistome in an urban lagoon system

Rapid urbanization has resulted in pervasive occurrence of antibiotic resistance genes(ARGs)in urban aquatic ecosystems.However,limited information is available concerning the ARG profiles and the forces responsible for their assembly in urban landscape lagoon systems.Here,we employed high-throughput quantitative PCR(HT-q PCR)to characterize the spatial variations of ARGs in surface and core sediments of Yundang Lagoon,China.The results indicated that the average richness and absolute abundance of ARGs were 11 and 53 times higher in the lagoon sediments as compared to pristine reference Tibetan lake sediments,highlighting the role of anthropogenic activities in ARG pollution.Co-occurrence network analysis indicated that various anaerobic prokaryotic genera belonging to Alpha-,Deltaproteobacteria,Bacteroidetes,Euryarchaeota,Firmicutes and Synergistetes were the potential hosts of ARGs.The partial least squares-path modeling(PLS-PM)analysis revealed positive and negative indirect effects of physicochemical factors and heavy metals on the lagoon ARG profiles,via biotic factors,respectively.The horizontal(mediated by mobile genetic elements)and vertical(mediated by prokaryotic communities)gene transfer may directly contribute the most to drive the abundance and composition of ARGs,respectively.Furthermore,the neutral community model demonstrated that the assembly of sediment ARG communities was jointly governed by deterministic and stochastic processes.Overall,this study provides novel insights into the diversity and distribution of ARGs in the benthic habitat of urban lagoon systems and underlying mechanisms for the spread and proliferation of ARGs.