Controlling effect of tectonic-paleogeomorphology on deposition in the south of Lufeng sag, Pearl River Mouth Basin

Paleogene depositional systems in the south of Lufeng sag have complex spatial distribution, which are influenced by pre-depositional paleogeomorphology and multi-period tectonic activities. In this paper, to clarify the controlling effect of tectonic-paleogeomorphology on sedimentary facies distribution and effectively guide oil and gas exploration, the Paleogene paleogeomorphic pattern in the south of Lufeng sag is reconstructed by the impression method, and the temporal and spatial evolution laws of the main faults are clarified. The results show that braided river deltas developed stably in the long-axis gentle slope belt of the lake basin, while the short-axis sedimentary system changed from fan deltas to braided river deltas in response to the change of active strength of dominant faults from strong to weak. It is found that the scale of the sedimentary fan is closely related to the activity of the main fault, the area of the catchment, and the vertical elevation difference. The steep cliff is controlled by the boundary fault with large fault throw and steep section, and there are wedge-shaped sand bodies near the steep cliff. The multi-level fault-step zone provides the driving force for the advancement of the sedimentary system, and the sand body extends for a long distance. It is established that the supply capacity of the source area and the accommodated space of the lake basin are coupled to control the deposition scale. Moreover, the slope controlled by the combination of paleogeomorphic assemblage and the activity of the main fault determines the sedimentary type, and the structural slope-break zone defines the spreading pattern of the sands.Cited as: Jiang, M., Chen, D., Chang, X., Shu, L., Wang, F. Controlling effect of tectonic-paleogeomorphology on deposition in the south of Lufeng sag, Pearl River Mouth Basin. Advances in Geo-Energy Research, 2022, 6(5): 363-374. https://doi.org/10.46690/ager.2022.05.0

Decreased buffering capacity and increased recovery time for legacy phosphorus in a typical watershed in eastern China between 1960 and 2010

Legacy phosphorus (P) accumulated in watersheds from excessive historical P inputs is recognized as an important component of water pollution control and sustainable P management in watersheds worldwide. However, little is known about how watershed P buffering capacity responds to legacy P pressures over time and how long it takes for riverine P concentrations to recover to a target level, especially in developing countries. This study examined long-term (1960–2010) accumulated legacy P stock, P buffering capacity and riverine TP flux dynamics to predict riverine P-reduction recovery times in the Yongan watershed of eastern China. Due to a growing legacy P stock coupled with changes in land use and climate, estimated short- and long-term buffering metrics (i.e., watershed ability to retain current year and historically accumulated surplus P, respectively) decreased by 65% and 36%, respectively, resulting in a 15-fold increase of riverine P flux between 1980 and 2010. An empirical model incorporating accumulated legacy P stock and annual precipitation was developed (R2 = 0.99) and used to estimate a critical legacy P stock of 22.2 ton P km−2 (95% CI 19.4–25.3 ton P km−2) that would prevent exceedance of a target riverine TP concentration of 0.05 mg P L−1. Using an exponential decay model, the recovery time for depleting the estimated legacy P stock in 2010 (29.3 ton P km−2) to the critical level (22.2 ton P km−2) via riverine flux was 456 years (95% CI 353–560 years), 159 years (95% CI 57–262 years) and 318 years (95% CI 238–400 years) under scenarios of a 4% reduction in annual P inputs, total cessation of P inputs, and 4% reduction of annual P inputs with a 10% increase in average annual precipitation, respectively. Given the lower P buffering capacity and lengthening recovery time, strategies to reduce P inputs and utilize soil legacy P for crop production are necessary to effectively control riverine P pollution and conserve global rock P resources. A long-term perspective that incorporates both contemporary and historical information is required for developing sustainable P management strategies to optimize both agronomic and environmental benefits at the watershed scale

Particle dynamics revealed by 210Po/210Pb disequilibria around Prydz Bay, the Southern Ocean in summer

Seawater samples were collected around Prydz Bay in summer of 2014, dissolved and particulate 210Po and 210Pb were measured to reveal the disequilibrium characteristics and particle dynamics. Our results show that the distribution of 210Po and 210Po/210Pb activity ratio in the upper water is mainly affected by biological absorption or particle adsorption. An abnormal excess of 210Po relative to 210Pb was observed in the surface water at stations P1-2 and P2-2, which is likely to be the horizontal transport of water mass with high DPo/DPb)A.R. and TPo/TPb)A.R.. In this study, the removal of particulate 210Po is mainly controlled by the scavenging of dissolved 210Po and the two have a linear positive correlation with the salinity, a negative linear correlation with the content of dissolved oxygen and a reciprocal relationship with the content of POC. The export flux of POC at 100 m is estimated to be 1.8–4.4 mmol·m−2·d−1 (avg. 2.9 mmol·m−2·d−1) based on 210Po/210Pb disequilibria, with the highest value in the shelf, which is consistent with the distribution of biological productivity

Monolithic quantum-dot distributed feedback laser array on silicon

Electrically-pumped lasers directly grown on silicon are key devices interfacing silicon microelectronics and photonics. We report here, for the first time, an electrically-pumped, room-temperature, continuous-wave (CW) and single-mode distributed feedback (DFB) laser array fabricated in InAs/GaAs quantum-dot (QD) gain material epitaxially grown on silicon. CW threshold currents as low as 12 mA and single-mode side mode suppression ratios (SMSRs) as high as 50 dB have been achieved from individual devices in the array. The laser array, compatible with state-of-the-art coarse wavelength division multiplexing (CWDM) systems, has a well-aligned channel spacing of 20 0.2 nm and exhibits a record wavelength coverage range of 100 nm, the full span of the O-band. These results indicate that, for the first time, the performance of lasers epitaxially grown on silicon is elevated to a point approaching real-world CWDM applications, demonstrating the great potential of this technology

Electrically pumped continuous-wave O-band quantum-dot superluminescent diode on silicon

High-power, broadband quantum-dot (QD) superluminescent diodes (SLDs) are ideal light sources for optical coherence tomography (OCT) imaging systems but have previously mainly been fabricated on native GaAs- or InP-based substrates. Recently, significant progress has been made to emigrate QD SLDs from native substrates to silicon substrates. Here, we demonstrate electrically pumped continuous-wave InAs QD SLDs monolithically grown on silicon substrates with significantly improved performance thanks to the achievement of a low density of defects in the III-V epilayers. The fabricated narrow-ridge-waveguide device exhibits a maximum 3 dB bandwidth of 103 nm emission spectrum centered at the O-band together with a maximum single facet output power of 3.8 mW at room temperature. The silicon-based SLD has been assessed for application in an OCT system. Under optimized conditions, a predicted axial resolution of ∼5.3µm is achieved with a corresponding output power of 0.66 mW/facet

Efficient Thermal Conductance in Organometallic Perovskite CH3NH3PbI3 Films

Perovskite-based optoelectronic devices have shown great promise for solar conversion and other optoelectronic applications, but their long-term performance instability is regarded as a major obstacle to their widespread deployment. Previous works have shown that the ultralow thermal conductivity and inefficient heat spreading might put an intrinsic limit on the lifetime of perovskite devices. Here, we report the observation of a remarkably efficient thermal conductance, with conductivity of 11.2 +/- 0.8 W m^-1 K^-1 at room temperature, in densely-packed perovskite CH3NH3PbI3 films, via noncontact time-domain thermal reflectance measurements. The temperature-dependent experiments suggest the important roles of organic cations and structural phase transitions, which are further confirmed by temperature-dependent Raman spectra. The thermal conductivity at room temperature observed here is over one order of magnitude larger than that in the early report, suggesting that perovskite device performance will not be limited by thermal stability