Guangzhou Institute of Geochemistry
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Interhemispheric synchrony of Mid-Late Holocene SST in the Indo-Pacific warm pool linked to upper water column dynamics
No full textThe sea surface temperature (SST) of the Indo-Pacific warm pool (IPWP) plays a crucial role in global climate system. Despite its importance, knowledge of its SST changes over century to millennial timescales remains limited and controversial, hindering our comprehensive understanding of climate change mechanisms. Our study bridges this gap with a novel SST reconstruction spanning approximately 7000 years, derived by aggregating 75 coral Sr/Ca-SST records from the South China Sea. These records reveal a notable synchronization in SST variations with foraminiferal reconstructions across the IPWP, reflecting a prevalent pattern of interhemispheric cooling and multi-century variability in the IPWP during the Mid-Late Holocene. Further analysis reveals that these (sub)millennial SST variations are closely linked to subsurface water temperature and ocean heat content (OHC) changes, supporting the theory that the release of deeper OHC acted as a heat source for low-latitude processes during the Holocene
Emerging Pollutants
No full textWith the rapid development of current society and economy, as well as the accelerated process of industrialization and urbanization, the complexity and seriousness of environmental pollution issues are becoming increasingly apparent. Beyond traditional pollutants, the appearance of emerging pollutants on a global scale has brought new challenges to environment and public health. China's "14th Five-Year Plan" and medium and long-term planning put forward "emerging pollutant control", report of the 20th National Congress of the Communist Party of China also explicitly requested "carry out emerging pollutant control". In 2022, General Office of the State Council issued "Action Plan for Emerging Pollutant Control", followed by the Ministry of Ecology and Environment and various provinces, municipalities, and autonomous regions, which released corresponding implementation plans, China has transferred to a new phase of environmental protection that balances the control of both traditional and emerging pollutants. However, management of emerging pollutants is a long-term, dynamic and complex systematic project, which urgently needs to strengthen top-level design as well as scientific and technological support. Conducting systematic research on emerging pollutants not only provides effective scientific guidance for their control and improves the level of environmental quality management, but also assists our country in fulfilling international conventions, enhances the discourse power in global environmental governance, ensures our country environmental security, food security, international trade security, etc., and is of great significance for realizing sustainable development. This review aims to comprehensively explore various aspects of emerging pollutants, including their types and characteristics, production, use and emission, identification and detection, environmental occurrence, migration and transformation, ecotoxicological effects, human exposure, health risks, and management strategies. Furthermore, it looks forward to the future research direction, with a view to providing a scientific basis and decision-making support for control of emerging pollutants in China
Advances in Geochemical Monitoring Technologies for CO<sub>2</sub> Geological Storage
No full textCO2 geological storage, as a large-scale, low-cost, carbon reduction technology, has garnered widespread attention due to its safety. Monitoring potential leaks is critical to ensuring the safety of the carbon storage system. Geochemical monitoring employs methods such as gas monitoring, groundwater monitoring, tracer monitoring, and isotope monitoring to analyze the reservoir's storage state and secondary changes after a CO2 injection. This paper summarizes the recent applications and limitations of geochemical monitoring technologies in CO2 geological storage. In gas monitoring, the combined monitoring of multiple surface gasses can analyze potential gas sources in the storage area. In water monitoring, pH and conductivity measurements are the most direct, while ion composition monitoring methods are emerging. In tracer monitoring, although artificial tracers are effective, the environmental compatibility of natural tracers provides them with greater development potential. In isotope monitoring, C and O isotopes can effectively reveal gas sources. Future CO2 geological storage project monitoring should integrate various monitoring methods to comprehensively assess the risk and sources of CO2 leakage. The incorporation of artificial intelligence, machine learning technologies, and IoT monitoring will significantly enhance the accuracy and intelligence of numerical simulations and baseline monitoring, ensuring the long-term safety and sustainability of CO2 geological storage projects
Seismicity Migration and the Upper Crustal Structure in the Xinfengjiang Reservoir
No full textAfter the impoundment of the Xinfengjiang Reservoir (XFJR) in Guangdong, China, numerous earthquakes occurred in the area, including a magnitude 6.1 event in 1962. Analysis of historical earthquakes indicates that M >= 4 earthquakes began occurring in the northwestern XFJR in 2012, and seismicity has gradually migrated from the southeastern to the northwestern reservoir (NWR). However, the mechanisms governing the migration of seismicity and the current upper-crustal structure beneath the reservoir area remain unclear. In our study, we conducted tomographic imaging by combining waveform data from short-period and permanent stations to construct a 3D velocity model. Our high-resolution velocity models revealed a horizontal fractured zone at similar to 5 km depth that extends from the southeastern to northwestern XFJR, and a steep fault that extends to about 9 km depth. These two fractured zones may interact with each other, allowing for fluid infiltration and contributing to earthquake triggering via pore pressure diffusion in the XFJR areas. Furthermore, the calculation of Coulomb stress changes indicated that microearthquakes in the southeastern XFJR may contribute to the seismicity in the NWR. However, the influences of M >= 4 earthquakes in the northwestern XFJR on subsequent M >= 4 earthquakes in the southeastern XFJR vary differently. Our results provide crucial insights for understanding the migration of micro- earthquakes in the XFJR area
Tracing subducted oceanic slabs in the mantle by using molybdenum isotopes: A case study of intraplate basalts from Northeast China
No full textDetermining subduction-related processes is crucial for understanding lithological heterogeneity, as substantial quantities of slabs are recycled into the mantle. Molybdenum isotopes are valuable for distinguishing sources materials due to the significant isotope differences between the crust and the mantle. In this study, we systematically investigate Mo isotopes in a suite of well-characterized continental basalts from Keluo and Halaha-Chaoer, located in Northeast China. The delta 98Mo values of Keluo range from -0.41 to -0.23 parts per thousand, with an average of -0.34 parts per thousand, while Halaha-Chaoer samples ranged from -0.18 to -0.12 parts per thousand, with an average of -0.15 parts per thousand. The delta 98Mo values of Keluo basalts are lighter than the mean value of fresh oceanic basalts (-0.21 parts per thousand), whereas those of Halaha-Chaoer basalts are similar to oceanic basalts. Combined with other geochemical indications (LOI, Ce/Pb, La/Yb and so on), the Mo isotopic variations cannot be attributed to chemical weathering, continental crust contamination or magmatic processes. Instead, the delta 98Mo variations in this study are explained by the incorporation of different oceanic crustal materials into the magma sources. Correlations of delta 98Mo with Ba/Th, Th/U, 143Nd/144Nd indicated that both sediment and altered oceanic crust have significantly influenced these variations. This study demonstrates the potential of Mo isotopes to distinguish different types of recycled oceanic crust materials.
Our study indicates the great potential of Mo isotopes to distinguish different types of recycled oceanic crust materials in the mantle. imag
Uptake time and enrichment mechanism of rare earth elements in deep-sea bioapatite
No full textBioapatite is widely recognized as the primary carrier for rare earth elements and yttrium (REY) in deep-sea REYrich muds. The incorporation of REY into bioapatite occurs at the water-sediment interface, which has the potential to serve as a proxy for reconstructing paleoenvironmental conditions. The timing of REY uptake and the fractionation of rare earth elements (REEs) within bioapatite are crucial factors to understanding the application of these proxies. In this study, we present in-situ geochemical data for bioapatite obtained from surface sediments in the high sedimentation rate Somali Basin of the northwestern Indian Ocean (NWIO), as well as fish teeth within nodules from the low sedimentation rate in the northwestern Pacific Ocean (NWPO). Our findings indicate that the uptake time of REY occurred rapidly, with the Sigma REY content reaching 7265 mu g/g in bioapatite from the surface sediments in the NWIO within several thousand years. The bone fragments exhibited a high Sigma REY content, which was primarily attributed to substitution processes. This led to a notably elevated proportion of middle rare earth elements (MREE) compared to fish teeth. In contrast, the adsorption and substitution mechanisms responsible for REY incorporation decreased from the root to the tip in fish teeth, resulting in a pronounced decline in Sigma REY content. The adsorption mechanism was identified as the primary process responsible for REY uptake in the fish teeth within the studied nodules from the NWPO. The fractionation pattern of REEs in these teeth exhibited similarities to that of fish teeth from the NWIO. Therefore, we inferred that the fish teeth within the studied nodules may preserve the original information during late diagenesis. The variation of REY contents in the nodules was influenced by the redox environment, and there is no evidence to support the migration of REY from the nodules into the fish teeth
Tire Wear Chemicals in the Urban Atmosphere: Significant Contributions of Tire Wear Particles to PM<sub>2.5</sub>
No full textTire wear particles (TWPs) containing tire wear chemicals (TWCs) are of global concern due to their large emissions and potential toxicity. However, TWP contributions to urban fine particles are poorly understood. Here, 72 paired gas-phase and PM2.5 samples were collected in the urban air of the Pearl River Delta, China. The concentrations of 54 compounds were determined, and 28 TWCs were detected with total concentrations of 3130-317,000 pg/m(3). Most p-phenylenediamines (PPDs) were unstable in solvent, likely leading to their low detection rates. The TWCs were mainly (73 +/- 26%) in the gas phase. 2-OH-benzothiazole contributed 82 +/- 21% of the gas-phase TWCs and benzothiazole-2-sulfonic acid contributed 74 +/- 18% of the TWCs in PM2.5. Guangzhou and Foshan were "hotspots" for atmospheric TWCs. Most TWC concentrations significantly correlated with the road length nearby. More particulate TWCs were observed than model predictions, probably due to the impacts of nonexchangeable portion and sampling artifacts. Source apportionment combined with characteristic molecular markers indicated that TWPs contributed 13 +/- 7% of urban PM2.5. Our study demonstrates that TWPs are important contributors to urban air pollution that could pose risks to humans. There is an urgent need to develop strategies to decrease TWP emissions, along with broader urban air quality improvement strategies
A pyrolysis study of kerogen and extracted bitumen from a lacustrine shale of the Shahejie Formation and implications for in-situ conversion processes
No full textThe in-situ conversion process (ICP) is an important industry technology to develop oil resources in medium-low maturity shales, and laboratory-based kinetics studies are an effective method to predict yields at different temperatures and heating times for the in-situ conversion process. Previous studies on ICP focused mainly on kerogen. However, these studies seldom considered the contribution of bitumen in shale, which cracks into light hydrocarbons at high temperatures and affects the yields and compositions of hydrocarbons in ICP. In this study, gold tube pyrolysis experiments of kerogen and extracted bitumen from the Shahejie Formation shale (38.72-41.21 Ma, Eocene) were conducted at two heating rates (2 and 20 degrees C/h) and the yields and kinetic parameters of four components (C-1, C2-5, C6-14 and C15+) were obtained. Hydrocarbon yields and compositions in ICP processes are determined by applying kinetic parameters to different heating programs. For constant heating programs, the temperature determines the maximum yields in ICP. The maximum yields of methane from kerogen in ICP at constant temperatures of 300 degrees C, 350 degrees C and 400 degrees C are 24.08 ml/g, 99.57 ml/g and 166.82 ml/g, respectively. In addition, the percentage of methane from kerogen of the total methane yield gradually decreased to 55.22 %, 40.22 % and 31.26 %, respectively, which indicates that most of the methane is generated from extracted bitumen at high temperature. There is a maximum yield temperature for ICP, above which heavy hydrocarbons are cracked at high temperatures to produce non-hydrocarbons such as CO2 and inert carbon, which reduces the total hydrocarbon yield. The maximum yield temperature of the Es3(x) shale at 1 degrees C/day, 3 degrees C/day and 5 degrees C/day was 420 degrees C, 430 degrees C and 436 degrees C, respectively. The total hydrocarbon and gas-oil ratio (GOR) curves of ICP heating using first a rapid and then slow heating rate (the T5-1 program) and a heating rate of 1 degrees C/day are the highest and similar. However, when heating with the T5-1 program, it took only 0.48 years at geological conditions to reach the maximum yield temperature, saving 226 days. This study recommends the first fast and then slow heating path as the heating program for ICP. Confirming the compositions and maximum yield temperatures of ICP under different heating programs contributes to the design of engineering projects for industrial production
Unusual cobalt behaviors and enrichment in cobalt-rich crust from the Magellan seamounts in the Western Pacific
No full textMarine cobalt-rich (Co-rich) crusts are submarine critical metal resources with high economic value. In this study, detailed in-situ fine-scale morphological, mineralogical, and geochemical analyses were conducted on Co-rich crust from the Western Pacific. The Co-rich crust can be divided into three layers: (1) Layer 1 is the oldest anthracite layer and contacts with the substrate, showing a very dense laminated/columnar texture. Layer 1 can be further divided into two distinct sublayers: a lower black, massive, dense sublayer (Layer 1-1) and an upper black-to-brown sublayer (Layer 1-2). (2) Layer 2 is porous and locally vuggy, and its pore space is filled with a large amount of silicate detrital minerals and clay minerals. (3) Layer 3, on the top, is black and dense, with a dendritic, columnar/laminated texture. Co is very unevenly distributed throughout the whole crust, with three distinct Co-rich areas. Layer 3 is a typical hydrogenetic crust and has not undergone late alteration. The main processes for Co enrichment are specific adsorption-oxidation on Mn-oxides and the structural incorporation of Co3+ into Mn-oxide phases. The average Co content of the Layer 3 is much higher than that of the other two layers. The presence of abundant detrital and clay minerals, along with high levels of Al, Si, and Ti in Layer 2, indicates the incorporation of terrigenous material, resulting in a high average growth rate. However, these processes are not conducive to Co enrichment. In the phosphatized Layer 1, fluctuations in element content are significantly greater than in the upper, non-phosphatized layers. Phosphatization has resulted in the partial decomposition of the initial Co-rich micro-layers, which may have reactivated and migrated Co, contributing to secondary Co enrichment
Determination of Light and Condensate Oil Categories in a Complex Petroleum System by Fluorescence Parameters: A Case Study on the Northern Tazhong Uplift, Tarim Basin, China
No full textLight and condensate oils are high-quality fossil energy sources. Because light and condensate oils have complex origins and are generally dominated by light hydrocarbons with few diagnostic biomarkers, conventional geochemical methods have difficulty identifying their categories, especially in complex petroleum systems. In this study, the fluorescence lifetime (tau(oil)) and fluorescence spectral parameters (lambda(max), Q(510/430), and Q(650/500)) of light and condensate oils in the northern Tazhong Uplift of the Tarim Basin were systematically analyzed. The results indicate that the light and condensate oils in this area can be divided into three categories according to their fluorescence characteristics. For the TZ-I, TZ-II, and TZ-III oils, tau(oil) progressively increases, and the fluorescence spectra gradually shift blue with decreases in Q(510/430), Q(650/500), and lambda(max), which results from the successive decreases in gas invasion extent for the three types of Tazhong oils. Light hydrocarbons mainly consisting of saturated hydrocarbon fractions were carried by highly mature gaseous hydrocarbons from deep sources to relatively shallow reservoirs and mixed with early accumulated crude oils. The charged saturates reduced the fluorophore (polycyclic aromatic hydrocarbons, PHA) concentration in crude oil, weakened fluorescence quenching, and promoted fluorescence emission, which changed the fluorescence characteristics of crude oils. Correlation diagrams based on different fluorescence parameters as well as other parameters, including physical, geochemical, and associated gas parameters, provide a favorable method for determining light and condensate categories. Moreover, the fluorescence method exhibits great application potential for direct correlations between reservoir oils and inclusion oils in complex petroleum systems