Guangzhou Institute of Geochemistry
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Preface to the Special Topic on Air Pollution Complex Research in China: Recent Advances
No full textChemical characteristics, source apportionment of precipitation ion and the response to air quality in Kunming, southwest monsoonal area of China
No full textChemical composition (ion) of precipitation contains the information of atmospheric pollution, provides key scientific evidence for improving air quality and deposition flux to ecological environmental assessment in study region. The ion concentrations of 99 precipitation events (January 2013 to December 2014) in Kunming (southwest monsoonal region of China) were reported here with detailed study on the ion characteristics, sources tracing and influencing factors by correlation analysis (SPSS software), Positive Matrix Factorization (PMF) and Hybrid Single Particle Lagrangian Integrated Trajectory (HYSPLIT) models analysis. The results showed that the major ions were NH4+, Ca2+, SO42- and NO3-, accounting for 81% of the total ions. PMF model results estimated six sources: secondary inorganic product, metal-cement industrial source, construction dust source, chlorination industrial source, marine source and biomass combustion source. In addition, HYSPLIT results showed that Kunming was mainly affected by five air masses, with highest ionic flux from the southwest direction (Indian Ocean). The annual average concentration of precipitation ions from 2013 to 2020 show positive relationships to air quality index (AQI), which indicate that precipitation ions can record different types of human activities (i.e. "coal ban", energy structure transformation, fertilizer usage, etc.) contribute to AQI
From holocene to anthropogenic impact: Surpassing coral's pH up-regulation capacity under ocean acidification
No full textCorals' regulation of internal calcifying fluid (CF or cf) chemistry is crucial for their extraordinary calcification capacity, endowing them with a certain ability to cope with environmental changes such as anthropogenic ocean acidification (OA) and warming. However, it remains unclear whether the impacts of these changes on corals have substantially surpassed their regulation capacity, particularly in comparison to the CF chemistry responses to natural climate variability with minor or no human perturbation. In this study, we reconstructed the pH, dissolved inorganic carbon, and carbonate ion concentrations in coral CF (pH(cf), DICcf, and [CO32-](cf)) during the Mid- to Late-Holocene, by analyzing the skeletal delta B-11 and B/Ca of 80 Porites spp. from eastern Hainan Island in the South China Sea (SCS). Our records indicate considerable inter-colony variations in CF chemistry, with maximum disparities reaching 0.18 units for pH(cf) and 1664 mu mol/kg for DICcf. With this in mind, we found no clear responses of coral DICcf to the climate fluctuations during the past similar to 5500 years, nor evident differences in pH(cf) and [CO32-](cf) across pre-industrial natural epochs. However, pH(cf) and [CO32-](cf) of modern corals have significantly declined compared to fossil corals. Further analyzes compiling global data on Porites spp. also confirm this pronounced pH(cf) decrease in modern corals, suggesting the limitations of pantropical corals to counteract OA by up-regulating pH(cf). Importantly, these fossil and modern corals reveal a clear long-term pH(cf) descending trend parallel to atmospheric CO2 changes, supporting the reliability of coral delta B-11 in recording long-term changes in seawater pH (pH(sw))
Geochemical constraints on subduction-related mantle metasomatism of the Tiebaghi ophiolitic lherzolite in New Caledonia
No full textThe geochemical evolution of mantle peridotite during subduction initiation (SI) remains an issue in geosciences. This study presents geochemical and Ca isotopic data for Tiebaghi lherzolites from the New Caledonia ophiolite to constrain their petrogenesis and the nature of melt-rock interaction during the nascent stage of subduction. Petrographic and geochemical analyses reveal that the Tiebaghi lherzolites are characterized by olivine with Fo contents of 89.5-90.7, high-Al Spinel (Cr# = 45.1-50.9; Al2O3 = 24.99-29.29 wt%), orthopyroxene with high CaO (0.87-2.47 wt%) and Al2O3 (2.19-4.91 wt%) coupled with relatively low Mg# (89.4-91.3), and clinopyroxene with high Al2O3 (2.72-6.44 wt%) and relatively low Mg# (90.4-92.5). Lherzolites from northwestern New Caledonia are thought to have escaped the suprasubduction re-melting, resulting in the formation of the highly depleted harzburgites that form the bulk of the ophiolite. They display a restricted range of 5 44/40 Ca values (0.75-0.93 parts per thousand), which are lower than the proposed 5 44/40 Ca value of Earth's upper mantle. This isotopic signature is interpreted to reflect interaction with a low 5 44/40 Ca metasomatic agent, possibly a carbonate-rich melt derived from the subducting slab. These findings suggest that the Tiebaghi lherzolites preserve a geochemical record of the early stages of melt-rock interaction during subduction initiation, emphasizing the role of carbonate melt metasomatism in altering the composition of the nascent mantle wedge
Coral-derived seasonal seawater 518O records from the Northern South China Sea: Hydroclimatic insights into the Medieval Climate Anomaly and Little Ice Age
No full textSeawater oxygen isotopes ( 5 18 O sw ) are critical for reconstructing past climate and hydrological conditions, yet high-resolution 5 18 O sw reconstructions during the Medieval Climate Anomaly (MCA) and the Little Ice Age (LIA) remain scarce. Using paired monthly coral Sr/Ca-518O records from Hainan Island in the northern South China Sea (NSCS), we reconstructed wet and dry season 5 18 O sw for these periods. During the MCA, 5 18 O sw values were relatively positive, indicating drier conditions, while the LIA exhibited relatively negative 5 18 O sw values, reflecting wetter conditions. Compared to 1984-2014 CE, the frequency of seasonal extreme 5 18 O sw events increased by 25 %-74 %, likely driven by global warming caused by human activities. Long term trends reveal that dry season 5 18 O sw closely mirrored wet season values, emphasizing the key role of the wet season 5 18 O sw baseline in shaping seasonal hydrological conditions. When examined in the broader late Holocene context, East Asia exhibited a persistent meridional dry-wet contrast, with cold periods characterized by wet oceanic and dry inland conditions, and warm periods showing the opposite. These contrasting patterns were primarily driven by the combined influence of the East Asian Summer Monsoon and El Nino, with additional influences from the meridional shifts of the Intertropical Convergence Zone and zonal movements of the Pacific Walker Circulation. These findings underscore the dynamic interplay of regional climate drivers in shaping hydrological variability and highlight the NSCS's critical role in East Asia's climate. They provide valuable baselines for understanding natural climate variability and predicting future climate changes in this densely populated and economically significant region
Effect of polystyrene micro/nanoplastics on PCBs removal in constructed wetlands planted with <i>Myriophyllum aquaticum</i>
No full textThe co-occurrence of microplastics (MPs) and nanoplastics (NPs) with polychlorinated biphenyls (PCBs) is an emerging environmental concern. Wetland plants, with their unique anaerobic-aerobic environments, offer a promising approach for PCBs removal. However, the impact of MPs and NPs on PCBs dynamics in constructed wetlands is not well understood. This study examined the influence of polystyrene MPs and NPs of two different sizes on PCBs fate in constructed wetlands featuring Myriophyllum aquaticum. Results showed that although there was no significant difference in overall PCBs removal rates, the presence of MPs increased residues of highly chlorinated PCBs from 331 mu g/kg to 379 mu g/kg, while the presence of NPs increased residues of lightly chlorinated PCBs from 125 mu g/kg to 153 mu g/kg. Additionally, MPs and NPs increased plant uptake of PCBs from 0.08% to 0.10-0.14%, despite potential inhibition of plant growth. While MPs/NPs elevated microorganism counts, they did not affect microbial diversity or community structure. Importantly, MPs significantly inhibited the main PCB-dechlorinating bacteria ( Dehalococcoidia ) and had a greater impact on PCB-degrading enzymes (dioxygenase, K03381) compared to NPs. This study highlights the complex interactions between MPs/NPs and PCBs in wetland environments and their implications for bioremediation strategies
Atomic Insights into the Heterogeneous Crystallization of Manganese (Oxyhydr)oxides on Typical Iron (Oxyhydr)oxides: from Adsorption to Oxidation to Crystallization
No full textHeterogeneous crystallization of manganese (oxyhydr)oxides (MnO x ) on iron (oxyhydr)oxides (FeO x ) is crucial for the biogeochemical cycling of Mn, yet atomic-level insights into this process are important but relatively limited. Herein, we revealed the distinct adsorption, oxidation, and crystallization mechanisms of Mn on hematite (Hem), ferrihydrite (Fhy), and goethite (Gth). Gth exhibited highest ability in Mn(II) removal and oxidation, followed by Hem and Fhy. Manganite and hausmannite were the main MnO x products with distinct proportions, and morphologies cross the systems. MnO x growth mechanisms involve surface-induced nucleation, crystallization by particle attachment (CPA), and self-catalyzed growth. On Fhy, self-catalyzed growth was dominant; for Gth, surface-induced nucleation was prevalent, supplemented by CPA; and Hem combined all three mechanisms. These distinct mechanisms led to nanoparticles primarily of hausmannite on Gth and nanowires of manganite and hausmannite on Hem and Fhy, with those on Hem displaying lower aspect ratios. Differences in MnO x structure and morphology were attributed to Mn(II)-FeO x complexation, FeO x electronic band structure, and crystal structure mismatch between MnO x and FeO x , which respectively influenced the direct and indirect electron transfer and heterogeneous nucleation efficiency. This work advances our understanding of MnO x crystallization on FeO x at the nanoscale, explaining the diverse morphology and structure of MnO x in different environments
Location optimization of unmanned aerial vehicle (UAV) drone port for coastal zone management: The case of Guangdong coastal zone in China
No full textCoastal zones host diverse ecosystems and abundant natural resources but have become increasingly vulnerable in recent decades due to human activities and climate change. Effective management of coastal risks and sustainable development requires a continuous and efficient unmanned aerial vehicle (UAV) network to monitor coastal resources, natural hazards, and pollution events. Drone ports, as operational hubs for UAVs, provide essential support for autonomous monitoring, power management, and data synchronization. Optimizing the location of drone ports can significantly enhance monitoring efficiency, particularly in long, narrow coastal areas. This study proposes a technical framework for determining the optimal placement of drone ports within a coastal UAV monitoring network, tailored to the monitoring demands of coastal zone management (CZM). Using the Guangdong Province coastal area in China as a case study, we developed an optimization model for drone port locations. The study also emphasizes the need for technological adaptation to meet the specific demands of CZM applications, adhere to local UAV regulations, and navigate complex coastal environments. The innovations of this study lie in the development of a universal UAV network capable of supporting various CZM applications. The UAV network provides high-resolution data with high frequency and rapid response, and it can be seamlessly integrated with other monitoring technologies. These advantages enhance the ability to acquire fine-scale data, improving the effectiveness of coastal resource management and better informing adaptive strategies for local CZM sectors
Formation and evolution of environmentally persistent free radicals in charcoal and soot generated from biomass materials
No full textEnvironmentally persistent free radicals (EPFRs) are emerging pollutants that are highly reactive and toxic, posing potential health risks. Biomass burning is a significant source of EPFRs, but there has been a notable gap in research regarding the EPFRs present in charcoal and soot produced from the same combustion process. Our study detected EPFRs in both charcoal and soot, but there were significant differences in their characteristics. The EPFR concentrations in charcoal were much higher than that in soot, by approximately 2-4 orders of magnitude, suggesting that charcoal may be more chemically reactive. Differences in the formation mechanisms between charcoal and soot were found to result in variations in the characteristics of EPFRs observed in each material. Furthermore, the ability of EPFRs to generate reactive oxygen species (ROS) differed considerably between charcoal and soot. Charcoal exhibited a strong ability to produce ROS, including O-1(2) and center dot OH radicals, and the abundances of O-1(2) was further enhanced (similar to 1.2-2.1 times) after illumination. In contrast, only the O-1(2) radical was found in soot produced at 300 degrees C. These findings enhanced our understanding of the environmental impact and potential toxicity of EPFRs, offering valuable insights for evaluating the risks associated with wildfires and agricultural burning
Water solubility of olivine under redox-controlled deep upper mantle conditions: effects of pressure, temperature and coexisting fluids and implications
No full textWater as structural hydroxyl in olivine plays an important role in determining the water budget of the upper mantle and its numerous physicochemical properties. However, the solubility of water in olivine in the deep upper mantle (i.e., 300-410 km depth), which defines the maximum water content under given conditions, still needs to be known with high precision. We examined the water solubility by annealing experiments under conditions controlled by Fe-FeO buffer and peridotite assemblages at 10-13 GPa and 1100-1450 degrees C, using a starting olivine of representative chemistry and different fluid materials. The experimental conditions were broadly consistent with those prevailing in the deep upper mantle. The attainment of equilibrium water incorporation in the H-annealed olivine samples was ensured by H diffusion kinetics, water profile analyses and time-series studies. The annealed samples demonstrate infrared hydroxyl bands at 3650-3000 cm(-1), but the relative band patterns are different from those observed in the available H-annealing experiments at 1-7 GPa under otherwise comparable conditions (including starting materials). The obtained solubility of water increases with increasing both temperature and pressure over the run conditions, and differs apparently between the runs equilibrated by different fluids that are relevant to the deep upper mantle and water solubility studies. In general, the water solubility of olivine increases nonlinearly with increasing depth in the upper mantle, and can be described as: C-w = (290 +/- 78) x exp ((0.0043 +/- 0.0006) x depth (km))-(268 +/- 89) (H2O as coexisting fluid) and C-w = (149 +/- 72) x exp ((0.0046 +/- 0.0011) x depth (km))-(132 +/- 85) (CH4-H2O as coexisting fluid), where C-w is water solubility (ppm wt. H2O). The water solubility of olivine in the realistic upper mantle should be defined from the runs coexisting with CH4-H2O, and the highest value is only similar to 800 +/- 80 ppm wt. H2O, implying that the actual water contents of olivine in the upper mantle must be mostly (if not exclusively) lower. The inferred storage capacity of water in peridotite in the upper mantle reaches its maximum of 600 +/- 100 ppm wt. H2O (95% confidence level) at the bottom boundary of similar to 410 km depth, and a minimum of 350 +/- 50 ppm wt. H2O (95% confidence level) is expected at mid-depths of 190-230 km. During the upwelling of relatively water-rich materials from the source regions of enriched mid-ocean ridge basalts or ocean island basalts, hydrous melting would be much easier to trigger at the mid-depths of the upper mantle. The data further suggest that, to produce a pervasive hydrous melting at the similar to 410 km depth, the prevailing water content of the mantle transition zone should be greater than similar to 600 ppm wt. H2O