Earth-Science Reviews最新文献

Peatlands are potent landscape sinks of natural and industrial toxic metals and metalloids (TMMs) but the long-term sequestration of TMMs in peatlands is at increasing risk due to climate change enhanced peatland fires. The ability of peatlands to retain TMMs results from a host of interacting hydrological, biological, geomorphological, and chemical feedbacks, which underpin peatland functionality in general. Fire is a transformative force that often disrupts these interactions and feedbacks, leading to the potential release of TMMs to our air, land, and water. Given that wildfire burned area and severity are increasing there is a need for a conceptual understanding of these interactive processes. Prior to a fire, peatland TMM mobility is relatively low, controlled by a peatland's degree of minerotrophy, degradation status, hydrogeomorphic setting and hydroclimate. Incidentally, these peatland characteristics also control the likelihood of peat ignition, creating important feedbacks on the landscape. Following ignition, the temperature and duration of a peat fire plays a critical role in determining the potential TMM emissions to the atmosphere and the post-fire geochemical conditions. We elucidate the varied emission factors of different metals, where emission factors range from 0.2 (Co or Cd) to 300 (Al) mg of metal per kg of particulate matter emitted depending on the specific metal and likely the pre-fire peat metal concentration. Following a peat fire, the geochemical and hydrological changes become increasingly important. For example, post-fire increases in pH play the strongest chemical role in limiting TMM mobilization but concurrent increases in dissolved organic matter aromaticity complicate our understanding of these processes, leading to a critical knowledge gap. At larger spatial scales, peatland and watershed ecohydrological connectivity and peat erosion modulate the release of TMMs to aquatic systems. Yet, the evolution of the ecohydrological connectivity and peat erosion potential as the peatland vegetation and hydrology recover to pre-fire conditions over the course of several to tens of years is governed by the same controls that impact pre-fire TMM mobility. Critically, the uncertainty in evolution trajectories depends on changes in biological, hydrological, climatological, and chemical conditions, limiting our ability to accurately predict these changes under a rapidly changing climate. This extensive and interdisciplinary review guides the development of a conceptual framework and highlights future research needs to better respond to the emerging threat of legacy TMM release from peatland wildfires.

Microplastics (MPs), particles with a size <5 mm, are ubiquitous in water, soil, and atmosphere, and have become a highly discussed environmental issue. Although atmospheric MPs have received less attention than MPs in soil and water, their possible environmental consequences are being examined in more depth. This study systematically reviews the sources, transport, distribution, and variations of atmospheric MPs, their interactions with other pollutants in the environment and impact on human health based on the literature. The results show that MPs have been identified in diverse atmospheric settings such as urban, sub-urban, and remote areas as well as in indoor air. These airborne MPs can originate from terrestrial sources like landfills, synthetic clothing, and plastic manufacturing, use and recycling activities, as well as from aquatic sources like MPs resulting from bubble bursting. The outdoor MP abundance was detected in a range of 2 to 1159 MP/m²/day in depositions and 0 to 224 MP/m³ in suspended samples, while significantly higher abundance was observed indoors with depositions ranging from 22 to 760,000 MP/m²/day and suspended from 0.4 to 1583 MP/m³. The distribution characteristics of atmospheric MPs are affected by several factors such as urbanization, anthropogenic activities, indoor and outdoor environments and seasons. Atmospheric transport of MPs occurs through suspension, horizontal transport and deposition processes that are greatly influenced by the morphology of the MP, wind speed and direction, precipitation and other atmospheric factors. The transport path of MPs in the atmosphere is studied by Lagrangian atmospheric models by conducting backward trajectory simulations to estimate linear trajectories of MPs at sampling locations to discern their potential origin and travel distance. MPs can also interact with a variety of chemical pollutants and microorganisms in the environment and thus act as a vector for pollutant transport. The toxicity of MPs may be increased by the release of pathogens and chemical contaminants into the environment, thereby increasing the health risk to humans. Based on the study, it is suggested that further scientific research on atmospheric MPs should focus on the standardization of research methods, atmospheric transport mechanisms, interactions of MPs with atmospheric pollutants and ecological impacts. As MPs could enter the human body through various mechanisms, it is urgent to study their physiological effects on the human body when exposed to atmospheric MP pollution.

The “Xing'an-Baikal” permafrost is distributed in Eurasia's middle and high latitudes. It incorporates features observed in high-altitude and high-latitude permafrost, yet it possesses unique characteristics and is sensitive to climate and environmental changes. The characteristics of the “Xing'an-Baikal” permafrost are systematically summarized, including permafrost distribution, taliks, ground ice, active layer thickness, ground temperature, permafrost thickness, and both zonality and non-zonality patterns. Further, this study clarifies the changing characteristics of regional degradation and local growth of permafrost under climate warming and environmental changes. The significant changes occurring in the “Xing'an-Baikal” permafrost are assessed in terms of their important and ongoing impacts on regional water‑carbon cycles, ecological succession, landscapes and engineering in cold regions. The interchange between beneficial and adverse effects is revealed in the process of permafrost degradation. In the future, a comprehensive understanding of the degradation pattern of the “Xing'an-Baikal” permafrost necessitates strengthened regional surveys and long-term continuous monitoring. Model development should account for the unique characteristics of the “Xing'an-Baikal” permafrost and its environment changes, enhancing the accuracy of research on permafrost change and environmental evolution. Through the systematic and comprehensive elaboration of the mechanisms underlying synergistic permafrost-environment evolution, these efforts will provide a scientific basis for responding to climate warming and promoting sustainable regional development.

As a typical intracontinental orogenic belt, the Tian Shan is a natural lab for the understanding of ongoing intraplate deformation and related geodynamic mechanisms. Knowledge of the spatial and temporal patterns of uplift and exhumation of the range can provide critical insights into this issue. This work used apatite U-Th/He thermochronological analysis and river profile inversion to reveal the histories of exhumation and uplift of the Sikeshu catchment, northern Chinese Tian Shan. Also, the spatiotemporal variations in the rate of exhumation across the Tian Shan were investigated, by inverting from a dataset of 1817 compiled apatite and zircon fission track and U-Th/He ages. The results indicated that, the exhumation across the entire Tian Shan primarily began during the early Miocene, with a significant, range-wide enhancement of exhumation occurring around 10 Ma. When combining the independent evidence of mountain uplift from sedimentology, rock magnetism, and structural modelling, we propose a two-stage model of exhumation, uplift, and basinward propagation of the modern Tian Shan, i.e., initial, range-wide rejuvenation around 20 Ma and intensive uplift and rapid exhumation since about 10 Ma. By integrating previous geophysical and geological studies on the Tibetan Plateau, the significantly enhanced exhumation across the entire Tian Shan since ∼10 Ma can be attributed to the Indian-Tarim collision at this age.

The Kellwasser event is one of Big Five mass extinctions of the Phanerozoic. It marks the boundary between the Frasnian and the Famennian, the two stages of the Upper Devonian. In order to discuss its effects on marine ostracod faunas, all well-dated occurrences from the literature have been gathered. We estimate that, at a global scale, the Kellwasser event has been responsible for the disappearance of 80% of ostracod species. However, the effect on ostracods was geographically heterogeneous, with values varying from 61% to 91%, probably related to local parameters. Our analyses show that this event mostly affected the ostracod diversity at low taxonomic levels (species and genera). Both nearshore and deep (Thuringian) benthic ostracods were affected. This event also influenced pelagic taxa, mostly represented by Entomozoidae, but they were still less affected than benthic ones at the global scale. Together with ostracods of the genus Bairdia (Bairdiidae, Podocopida), Entomozoidae are among the most diversified taxa represented in event assemblages, suggesting that they were more tolerant to oxygen depletion as it was proposed, at least for Bairdia, for the Permian-Triassic event. We show that the faunal recovery has mostly been characterized by diversification among cosmopolitan (particularly Bairdiidae and Bairdiocyprididae) and Thuringian taxa (particularly Bythocytheridae and, to a lesser extent Healdiidae, Tricorninidae and Rectonariidae). A global increase in endemism is observed through the Kellwasser event, likely related to the diversification of deep-water Thuringian taxa, leading to an increase in differences of taxonomic composition between the palaeoenvironmental settings. The widely reported sea-level fall at this time interval could also have participated in the increase in endemism by reducing the connexion between nearshore areas. This work is the first part of a two-part study focusing on the changes in ostracod community throughout the two Late Devonian biological crises (Kellwasser and Hangenberg events).

Over the past two decades, advancements in geochronological, sedimentary, and geochemical studies have considerably deepened our understanding of the links between the deposition of Neoproterozoic iron formations (NIFs) and major changes in Earth's surface environment. In China, extensive studies within this period have revealed that NIFs exhibit a wide range of fabrics, lithofacies, and geochemical properties, indicating their deposition occurred in a range of environments. Chinese NIFs can be categorized into four types based on lithofacies associations and depositional settings: (1) syn- and de-glacial NIFs that are associated with glacial deposits in glaciomarine or sub-ice environments; (2) inter-glacial NIFs associated with non-glaciogenic deposits in oceans that lacked sea ice during the Cryogenian; (3) volcanism-related NIFs found with volcanic rocks in extensional basins related to the break-up of the supercontinent Rodinia; and (4) non-glaciogenic and non-volcanogenic NIFs that are intercalated with shales and carbonates, and were likely deposited on the continental shelf. Accordingly, we propose a unified model that emphasizes multiple factors controlling the deposition of NIFs at the global scale. Furthermore, we propose that the termination of NIF deposition was probably related to rising oxygen levels on Earth's surface during the late Neoproterozoic.

The Jiaodong Peninsula in the eastern North China Craton is well-known for world-class deposits and as the only known late Mesozoic giant gold province located within a Precambrian metamorphic terrane. Here we synthesize deep seismic reflection data from the Jiaodong Peninsula, and on conjunction with existing interpretations of magnetotelluric data. We provide a new interpretation that offers insights into the possible crust-mantle interaction and deep ore-forming processes in this supergiant gold province. Six high-yield NNE-trending gold mineralized fault zones that span approximately 420 km across strike are identified: Sanshandao, Jiaojia, Zhaoping, Qixia, Guoji, and Muru. We identify distinct features in the coupled crust and lithospheric mantle beneath the Jiaodong gold province including a metamorphic core complex (MCC) and detachment fault systems at shallow crustal levels, a mid-crustal detachment belt (MCDB), a low-angle reverse fault in the lower crust, a reflection-transparent region and crust-mantle transition zone (CMT), as well as a deeper Moho discontinuity. Our study also reveals clear detachment or absence of the Moho and CMT beneath the Tan-Lu and Wulian-Yantai fault zones, the presence of weak wave impedance, or reflection-transparent regions in the deep parts of the high-angle faults, such as the Tan-Lu and Wulian-Yantai faults, and that in the core of the Linglong MCC. These are interpreted as zones formed through the homogenization of crustal materials as a result of the upward migration of heat, magmas, and fluids from the lithospheric mantle to the middle and upper crust. Important auriferous fluid pathways from the Moho include reverse faults at lower crustal levels, the MCDB, and detachment fault systems at upper crustal levels. The fluid pathway systems played a crucial controlling role in the intensity of formation of gold deposits. The CMT and MCDB are thicker, and the mineralization intensity and known gold resources are greater, where they are closer to the mantle-derived melt and fluid pathway.

We propose a new two-stage model to explain the origin of the giant Jiaodong gold deposits which is based on the crust-mantle interaction as indicated by seismic reflection and magnetotelluric profiles, combined with existing experimental petrology and thermodynamic simulations, as well as information on mineralization and tectonothermal events based on isotope data. We envisage that the subduction-collision at ∼250–220 Ma between the Yangtze and North China cratons resulted in the formation of enriched lithospheric mantle that served as one of the important sources of auriferous fluids. At ∼120 Ma, asthenosphere upwelling, which induced metasomatism and partial melting in the overlying enriched lithospheric mantle, resulted in the activation, migration and concentration of gold, generating one of the world's giant gold fields.

Biochar, the solid product of biomass pyrolysis, has been widely used to mitigate global climate change by storing carbon (C) and regulating the transformation of nitrogen (N) in soil. While the effects of biochar on soil C and N cycles, such as mineralization and plant uptake, have been extensively reported, most studies of these types have employed measurement of the changes in total C and N in soil following biochar addition. However, this does not allow for the determination of the sources of C and N in soil that are utilized or transformed. Isotope technology has great potential in evaluating the effects of biochar on the biogeochemical behavior of soil C and N because it can distinguish added biochar C and N from native C and N and other sources of organic matter and determine the transformation or loss rate of each source. However, at present, most studies on this aspect are scattered and the conclusions are inconsistent. Therefore, a systematic review of studies using the C and N isotopes in biochar research is needed. In this paper, the advantages and disadvantages of the application of C and N isotopes to biochar research are summarized, and the findings of these studies as related to the effects of biochar on soil C and N cycles were reviewed, including biochar and native C persistence, CO₂ and N₂O emissions, and plant N uptake. Finally, some recommendations for future directions on C and N isotopes in the field of biochar research are made. This review could lay a theoretical foundation and encourage the application of C and N isotope technology to the field of biochar research.

Chile is the world's leading producer of many terrestrial mineral resources; however, the potential of the country's marine mineral resources has been largely overlooked. Within its continental shelf (up to 200 nautical miles from the baselines from which the breadth of the territorial sea is measured), Chile has favorable geological characteristics for hosting and forming marine minerals and energy resources.

During the last decades, several novel studies have demonstrated the potential of gas hydrate reservoirs in Chile (between 33° and 56°S) as an energy resource and source of greenhouse gases, which has attracted the attention of the Chilean scientific community. In addition, some studies have highlighted the potential value of marine minerals in the Chilean continental shelf, mainly due to the increasing demand for minerals for low-carbon energy production, such as cobalt-rich ferromanganese crusts, polymetallic nodules, and massive sulfides on the seafloor.

The goal of this study is to review all information on the non-conventional energy and mineral resources of the Chilean continental shelf. Furthermore, we provide data (e.g., core samples, seismic profiles, or research from related papers) on marine deposits in the Chilean seabed. Here, we show unpublished seismic images of a previously unidentified massive hydrate deposit in the southernmost part of the 1960 Valdivia earthquake rupture zone, which was the largest earthquake recorded in history. We also present geological data that suggests the presence of nodules, sulfides, and crusts on the Chilean continental shelf. Collectively, these findings represent the most important but least explored resources for critical elements and base metals in the country.

This study provides a primer for policymakers to apprise them of future research needed to develop potential mineral and energy resources within prospective deep-sea areas. It also includes advice on developing an environmental baseline for future environmental impact assessment. The new understanding of mineral and energy resources presented here greatly expands Chile's position beyond that as a source of terrestrial minerals to include potentially vast marine-based energy and metal resources, which are highly valued by industry. Based on these considerations, we encourage decision makers to promote and support studying marine deposits to further protect and evaluate future exploration.