ALBERT

Description: In this project we aim to develop a low-cost technology to remove ionic constituents from raw waters such as arsenic species. The proposed technology is based on the reactivity of schwertmannite, an oxyhydroxosulfate of the mean stochiometry Fe8O8(OH)6SO4 (molar mass 772.89 g/mol). This mineral typically forms in acidic and sulfate rich mine waters as a secondary mineral upon oxidation of Fe(II) in a biologically mediated process. Schwertmannite can be generated in a biotechnological process after aeration of mining process waters. It forms surface-rich aggregates of needle-like nanocrystals. It rapidly transforms into ferric hydroxides of high specific surface area once exposed to water containing at least some alkalinity. Our rationale follows the concept to make use of this transformation reaction by adding biosynthesized schwertmannite to contaminated raw waters where it generates a large sorption capacity to remove the pollutants (Peiffer et al., 2008).

Description: Scandium is important in modern technology and is regarded as a strategic metal in many countries. It is highly dispersed in Earth’s crust and rarely forms independent minerals. Clinopyroxene is the most important Sc-bearing mineral in some world-class deposits hosted in mafic–ultramafic intrusions, which are also the major source of laterite-hosted Sc deposits. However, the factors controlling Sc distribution in minerals have been little explored, impeding the understanding of the geochemical behavior of Sc and why it is common in some clinopyroxene grains. The newly discovered Mouding Sc deposit in SW China is hosted in a zoned intrusion composed, from core to rim, of monzogabbro, syenogabbro, gabbro, magnetite clinopyroxenite, and clinopyroxenite. Clinopyroxene in the intrusion is diopsidic in composition with high Sc contents (80–105 ppm). In-situ trace element mappings of diopside crystals reveal homogeneous, zoned, swallow-tailed, and hourglass internal Sc distribution patterns. These patterns can be produced through kinetically controlled incorporation of Sc on different crystal faces. The preferential substitution of Sc can take place on the {1 0 0}, {1 1 0} and {0 1 0} prism faces because of the high flexibility of the octahedral M1 protosites. The fast growth of diopside, which facilitates kinetically controlled crystallization, is dominated by textural coarsening and promoted by the hydrous parental magmas with low viscosities and active convection. The active flow and efficient interstitial communication of the magma can direct compatible elements from the magma into clinopyroxene, thus favoring formation of Sc-rich grains. Our study provides a feasible way to study intra-grain variations of Sc in minerals and emphasizes that kinetic effects may play a critical role in Sc distribution and enrichment in hydrous magmatic Sc deposits. We also show that disequilibrium crystallization may be more pervasive than previously thought, and the hourglass zoning of clinopyroxene can provide valuable information on this process.

Description: Monitoring ground displacement produced by underground mining is essential to ensure the safety of infrastructure over mining areas. Differential synthetic aperture radar (DInSAR) can only obtain the one-dimensional (1D, i.e., along the line-of-sight (LOS) direction) displacement component. In this study, we present an improved algorithm for retrieving and predicting three-dimensional (3D) displacement fields induced by underground mining based on the LOS displacement derived from DInSAR and the probability integral method (PIM). Whole parameters included in the standard PIM model are involved in the improved algorithm. In addition, the interaction between multiple working panels is considered and incorporated into the model. Next, a stochastic optimization technique hybridizing the cultural algorithm and random particle swarm optimization (CA-rPSO) has been designed to retrieve model parameters, which can be used to retrieve and predict the 3D displacement field. Simulated experiments show that the RMSEs are 10 mm, 12 mm and 17 mm in the vertical, east-west and north-south directions, respectively, by comparing the simulated and retrieved 3D displacement. Furthermore, the capability of the proposed method is investigated and validated in the Xuehu mining area of China using three ALOS PALSAR acquisitions. Our results agree well with levelling measurements in the vertical direction with a RMSE of 38 mm. Although the retrieved horizontal displacement cannot be validated due to a lack of field surveys, these displacement fields coincide spatially with the evolution of mining excavation.

Description: The phase delay caused by ionosphere is a major source of error in L-band Interferometric Synthetic Aperture Radar (InSAR) measurements. Several methods have already been proposed for ionospheric delay correction in InSAR data, each of them has its own advantages and disadvantages. Corrections using Multiple Aperture Interferometry (MAI) and Amplitude Tracking (AT) have been applied in the past, aim at generating shift along azimuth direction. The ionospheric phase can then be evaluated by estimating the approximate linear relationship between the azimuth shift and ionospheric phase streak. The use of MAI for wide-swath ScanSAR data from ALOS-2 that have been focused with the "full-aperture" approach of JAXA. It is problematic as it results in to significant azimuth depending loss of coherence due to doppler spectrum changing in azimuth direction of ScanSAR data. Amplitude tracking method can be applied, but will also be problematic if there is obvious surface displacement in the study area. We evaluate the use of existing ionosphere product from Center for Orbit Determination in Europe (CODE) for ionospheric phase correction of ALOS-2 ScanSAR interferograms. CODE provides global ionospheric map (GIM) using data from 200 GPS/GLONASS stations of the IGS and other institutes. This product contains global covered vertical total electron content (VTEC) map with a resolution of 5 degree by longitude and 2.5 degree by latitude. To down-scale this product to a resolution sufficient for InSAR observations we use spherical harmonics expansion and calculate ionospheric phase delay for a grid appropriate for InSAR observation data. The performance of the corrections baseon on this down-scaled CODE product is evaluated against other correction methods for pairs of L-band ScanSAR interferograms covering preseismic, coseismic and postseismic deformation of the 2016 Mw 7.8 earthquake in Ecuador.

Description: Constraining the Cenozoic uplift of Tian Shan is important for assessing the impact of the India-Asia collision to Central Asia. Here we estimate the uplift history of the Bogda Shan, northeastern Tian Shan, using a thermo-kinematic model which is constrained by previously reported apatite fission-track thermochronological data. By assuming that the growth of the mountain range propagates towards the basin as a classic critical wedge model, we show that the observed variation in the cooling ages on the mountain flank can be used to provide constraints on the timing and rate of the deformation along a series of south dipping thrust faults, which all root on a low-angle décollement. Inverse modeling confirms previous findings from thermal history models that the Cenozoic uplift in the Bogda Shan initiated during the Paleogene, no later than ~40 Ma. Since the early Miocene (~23 Ma), locus of uplift has expanded to the current southern margin of the Junggar Basin. Our kinematic model of the deformation of the Bogda Shan suggests a temporal stability in the shortening rate of the northeastern Tian Shan over the period of the India-Asia collision during the late Cenozoic.

Description: The symmetry of conjugate rifted margins is a first-order observable feature reflecting the geodynamic processes acting during and after continental rifting. The symmetry of the South China Sea (SCS) rifted margins can be deduced from comprehensive geophysical datasets on a continental-margin scale. Here, we combine three key approaches: (1) lateral fault distributions are delineated according to free-air gravity anomalies, (2) crustal stretching styles are mapped based on gravity inversion constrained by deep seismic profiles, and (3) total extension of conjugate margins is estimated according to margin restorations and tectonic settings. We infer a predominantly symmetric rifting style caused by pure shear extension, with only narrow domains of asymmetric deformation in continent-ocean transition (COT) regions that have undergone simple shear and where the lower crust of the highly thinned distal margin is embrittled before continental breakup. However, our analysis also suggests that this symmetry has been modified by post-rift geodynamic processes. Southward lower crustal flow, which occurred only on the southern margin due to the low viscosity of the lower crust and the slab pull induced by the subducting Proto-SCS plate during seafloor spreading, shifted the crustal stretching styles from symmetric to asymmetric. The collision between the southern margin and Borneo thickened the lower crust more than the upper crust at the southern end of the southern margin and shortened the southern margin. This event had a large impact on the SE margin but a small impact on the SW margin. We conclude that (1) for the SE and NE margins, the crustal stretching styles shifted from asymmetric to approximately symmetric, and the total extension shifted from symmetric to asymmetric; (2) for the SW and NW margins, the crustal stretching and total extension remained asymmetric and symmetric, respectively.

Description: A severe flooding hit the region of central east China to southern Japan in summer 2020. It is found that the extremely strong rainfall experienced pronounced subseasonal variation, dominated by a quasi-biweekly oscillation (QBWO) mode. The analysis of streamfunction of water vapor flux demonstrates that a large amount of water vapor eastward zonal transport from the Bay of Bengal and Indo-China and northward transport from the South China Sea provided the background moisture supply for the rainfall. The quasi-biweekly anomalies of potential and divergent component of vertically integrated water vapor flux played an important role in maintaining the subseasonal variability of extreme rainfall. The diagnosis of moisture tendency budget shows that the enhanced moisture closely related to the quasi-biweekly fluctuated rainfall was primarily attributed to the moisture convergence. Further analysis of time-scale decomposition in the moisture convergence indicates that the convergence of background mean specific humidity by the QBWO flow and convergence of QBWO specific humidity by the mean flow played dominant roles in contributing to the positive moisture tendency. In combination with adiabatic ascent over the rainfall region induced by the warm temperature advection, the boundary layer moisture convergence strengthened the upward transport of water vapor to moisten the middle troposphere, favoring the persistence of rainfall. The vertical moisture transport associated with boundary layer convergence was of critical importance in causing low-level tropospheric moistening.

Description: The East Asian winter monsoon (EAWM) exerts impacts on climate in the regions from East Asia down to the Maritime Continent. The El Niño-Southern Oscillation (ENSO) affects not only the tropical climate, but also the extratropical climate. This study evaluates the relationship between El Niño-Southern Oscillation (ENSO) and the East Asian winter monsoon (EAWM) in 26 Coupled Model Intercomparison Project phase 6 (CMIP6) models. Results show that the model’s ability of simulating the ENSO-EAWM relationship is more dependent upon the longitudinal extension of ENSO-related equatorial Pacific sea surface temperature (SST) anomalies than the amplitude of the equatorial central-eastern Pacific SST anomalies. The influence of the amplitude of ENSO on the simulation of the ENSO-EAWM relationship depends on the westward extension of ENSO-related equatorial Pacific SST anomalies. Another factor for the model’s ability of simulating the ENSO-EAWM relationship is the SST anomalies in the tropical western North Pacific (WNP). A westward extension of the equatorial Pacific SST anomalies shifts the west branch of anomalous Walker circulation too far westward, which causes westward displaced anomalous ascending (descending) motion around the Philippine Sea through modulating regional meridional vertical circulation in El Niño (La Niña) years. The weak SST anomalies in the tropical WNP lead to the failure of inducing anomalous lower-level anticyclone (cyclone) over the Philippine Sea through a Rossby wave response in El Niño (La Niña) years. The accompanying weak anomalous lower-level southwesterly (northeasterly) winds along the west flank of the anomalous anticyclone (cyclone) account for the weak ENSO-EAWM relationship.

Description: An open-ocean polynya is an offshore area where the sea ice is significantly less than that of its surrounding area. Polynyas are known as oases in Antarctic for driving the interactions between the atmosphere and the ocean. Extensive studies have addressed the characteristics and mechanisms of open-ocean polynyas in the Weddell and Cosmonaut Seas. The purpose of this study is to indicate the existence of more persistent open-ocean polynyas in the Cooperation Sea and propose the atmospheric and oceanic forcing mechanisms responsible for the formation of the open-ocean polynyas. Our results offer a more complete circumpolar view of open-ocean polynyas in the Southern Ocean and have implications for physical, biological, and biogeochemical studies of the Southern Ocean. Future efforts should be particularly devoted to more extensively observing the ocean circulation to understand the variability of open-ocean polynyas in the Cooperation Sea.