Residue Return Effects Outweigh Tillage Effects on Soil Microbial Communities and Functional Genes in Black Soil Region of Northeast China

Conservation tillage as an effective alternative to mitigate soil degradation has attracted worldwide attention, but the influences of conservation tillage on soil microbial community and especially function remain unclear. Shotgun metagenomics sequencing was performed to examine the taxonomic and functional community variations of black soils under three tillage regimes, namely no-tillage with residue(maize straw) return(NTS), moldboard plow with residue return(MPS), and moldboard plow without ...     

1958-2017年长江流域气候变化的时空特征与热点区域

The Yangtze River Watershed in China is a climate change hotspot featuring strong spatial and temporal variability;hence, it poses a certain threat to social development. Identifying the characteristics of and regions vulnerable to climate change is significantly important for formulating adaptive countermeasures. However, with regard to the Yangtze River Watershed, there is currently a lack of research on these aspects from the perspective of natural and anthropogenic factors. To address this issue, in this study, based on the temperature and precipitation records from 717 meteorological stations, the RClim Dex and random forest models were used to assess the spatiotemporal characteristics of climate change and identify mainly the natural and anthropogenic factors influencing climate change hotspots in the Yangtze River Watershed for the period 1958-2017. The results indicated a significant increasing trend in temperature, a trend of wet and dry polarization in the annual precipitation, and that the number of temperature indices with significant variations was 2.8 times greater than that of precipitation indices. Significant differences were also noted in the responses of the climate change characteristics of the sub-basins to anthropogenic and natural factors;the delta plain of the Yangtze River estuary exhibited the most significant climate changes, where 88.89% of the extreme climate indices varied considerably. Furthermore, the characteristics that were similar among the identified hotpots, including human activities(higher Gross Domestic Product and construction land proportions) and natural factors(high altitudes and large proportions of grassland and water bodies), were positively correlated with the rapid climate warming.     

Influence of Cathode Modification by Chitosan and Fe3+ on the Electrochemical Performance of Marine Sediment Microbial Fuel Cell

The electrochemical performances of cathode play a key role in the marine sediment microbial fuel cells(MSMFCs) as a long lasting power source to drive instruments, especially when the dissolved oxygen concentration is very low in seawater. A CTS-Fe³⁺ modified cathode is prepared here by grafting chitosan(CTS) on a carbon fiber surface and then chelating Fe³⁺ through the coordination process. The electrochemical performance in seawater and the output power of the assembled ...     

Petrogenesis and tectonic implications of the Early Cretaceous Dagushan adakitic porphyries in the Anshan area,North China Craton

The eastern part of the North China Craton suffered significant lithospheric thinning since the Mesozoic,and petrogenesis of the Dagushan adakitic diorite porphyries provides an excellent opportunity to investigate the lithospheric thinning mechanism and geodynamic setting.The zircon LA-ICP-MS U–Pb geochronology reveals that the representative Dagushan adakitic porphyry was formed at 120.5 ± 0.5 Ma.The Dagushan diorite porphyries are characterized by the relatively high contents of SiO2(64.25–65...     

Ambient Noise Tomography of Jinan: The Migration of Groundwater and the Formation of Geothermal Water

Jinan is an important city in eastern China, with rich groundwater in the region. There are four famous springs in the urban area and an abundance of geothermal water in the northern part, which makes the migration of groundwater in this area a very important issue. To study the shallow shear wave velocity structure and groundwater migration in Jinan, we utilized almost a month of continuous waveform data from 175 short period seismometers deployed by the Chinese Academy of Geological Sciences, in order to calculate the cross-correlation function. We picked 7749 group dispersion curves and 6117 phase dispersion curves with a period range of 0.2–2 s. Through inversion, we obtained the fine three-dimensional shear wave velocity and azimuthal anisotropy structure (0–2.4 km). Combining the results with local geological and hydrological data, the following conclusions were reached. (1) There are widespread high velocity anomalies in the region between the Qianfoshan and Wenhuaqiao faults, as well as to the east of the Wenhuaqiao Fault, which may be related to the intrusive gabbro known as the Jinan Intrusive Rock. (2) The two distinct high velocity anomalies in our model (referred to as west and east Jinan Intrusive Rock in this paper) may indicate that the Jinan Intrusive Rock was broken through crustal movement. (3) There is an obvious low velocity layer under the intrusive rock, which could be the channel of groundwater migration. The precipitation in the southern mountain region seeps down into the ground, then is blocked by the Jinan Intrusive Rock and can only progress downwards to a deeper part, where the groundwater is heated by the geothermal gradient. The heated water finally arrives at the northern part and forms geothermal water. (4) The depth of the low velocity layer beneath the Jinan Intrusive Rock varies laterally, which may indicate that the depth of the groundwater migration is different beneath the west and east Jinan Intrusive Rock. (5) There is strong azimuthal anisotropy in southern Jinan, with nearly E-W fast orientation, which may be related to the tilt limestone layering structure.     

Molecular phylogeny of familiar flatfish species(Pleuronectidae) in the northwestern Pacific Ocean based on mitochondrial cytochrome oxidase I gene

A molecular phylogenetic analysis was undertaken to evaluate the present systematic status of commercially familiar Pleuronectidae fishes in the northwestern Pacific Ocean. We sequenced a 529 bp fragment of the mitochondrial DNA （mtDNA） COl gene from 34 individuals of these familiar flatfishes from 11 species of nine genera collected in China and Japan. Genetic relationships among haplotypes of specimens from 11 species for COI gene data were reconstructed using the neighbour-joining method and the maximum parsimony （MP） method. The resulting molecular phylogeny of the 11 species, with a few exceptions, supported the existing taxonomy which was based largely on the morphological characteristics. The most noteworthy findings were that the genus Pleuronichthys diverged before deriving of the common ancestor for the other species; the stone flounder, Kareius biocoloratus, should belong to the genus Platichthys with the latin name Platichthys biocoloratus and the genus Verasper was not the extraordinary differ- entiation from the other species in family Pleuronectidae. The resultant phylogenetic trees were also consistent with multiple origins of direct development within family Pleuronectidae. New proof not only for further illuminating the multiple origins of Pleuronectidae but also for confirmation of the evolutionary relationships among groups in the family will be supported.     

Simulation of Extreme Updrafts in the Tropical Cyclone Eyewall

Strong vertical motion(>10 m s^-1) has profound implications for tropical cyclone(TC) structure changes and intensity. While extreme updrafts in the TC are occasionally observed in real TCs, the associated small-scale features remain unclear. Based on an analysis of the extreme eyewall updrafts in two numerical experiments conducted with the Advanced Research version of the Weather Research and Forecasting(WRF) model, in which the large-eddy simulation(LES) technique was used with t...     

Influences of the Great Whirl on surface chlorophyll a concentra-tion off the Somali Coast in 2017

The general features of the Great Whirl (GW) off the Somali Coast in 2017 and its influences on chlorophyll a (Chl a) concentration were studied by using satellite data and model outputs. Results show that GW, which initiated at 7°N, 53°E on June 13, had a lifetime of 153 d with an average amplitude of 16 cm and an average radius of 205 km. After the formation of GW, the concentration of Chl a in the interior of GW showed a downward trend throughout its life cycle, except in early July and mid-October. In early July, the Chl a blooms in the interior of GW were attributed to the combined effect of three processes. They are eddy horizontal transportation, the deepening of the mixed layer caused by the monsoon and eddy pumping, and the upward transportation of nutrients caused by eddy-induced Ekman pumping. In October, the Chl a blooms were probably due to the weakening of GW. During the period, water exchange occurred more frequently across the eddy, thus phytoplanktons were imported into the interior of GW.     

A Textural and Mineralogical Study of the Shanzhuang Banded Iron Formation, Southeastern Margin of the North China Craton: Implications for the Overprint History of Hydrothermal Alteration and Supergenesis after Mineralization

The newly discovered Shanzhuang BIF is hosted in the Shancaoyu Formation of the Taishan Group within the Eastern Block, southeastern margin of the North China Craton. The ores can be subdivided into three types in terms of mineral assemblages, corresponding to three types(I, II, III). The element concentration of the type I magnetite is similar to that of the type II magnetite, while the type III magnetite is similar to that of the schist. In general, magnetite and hemat ite grains from the ores...