Determining the role of richness and evenness in alpine grassland productivity across climatic and edaphic gradients.

Spatial heterogeneity of climatic and edaphic gradients can substantially affect the grassland productivity function. However, few studies have tested the importance of species richness and evenness on regulating grassland productivity across spatial-scale climatic and edaphic changes. This study examines the complex mechanisms by which species richness and evenness regulate productivity in alpine meadow and steppe.

Coupled atmosphere-ice-ocean dynamics during Heinrich Stadial 2.

Our understanding of climate dynamics during millennial-scale events is incomplete, partially due to the lack of their precise phase analyses under various boundary conditions. Here we present nine speleothem oxygen-isotope records from mid-to-low-latitude monsoon regimes with sub-centennial age precision and multi-annual resolution, spanning the Heinrich Stadial 2 (HS2) - a millennial-scale event that occurred at the Last Glacial Maximum. Our data suggests that the Greenland and Antarctic ice-core chronologies require +320- and +400-year adjustments, respectively, supported by extant volcanic evidence and radiocarbon ages.

The relationship between the intensified heat waves and deteriorated summertime ozone pollution in the Beijing-Tianjin-Hebei region, China, during 2013-2017.

Summertime ozone (O) pollution has frequently occurred in the Beijing-Tianjin-Hebei (BTH) region, China, since 2013, resulting in detrimental impacts on human health and ecosystems. The contribution of weather shifts to O concentration variability owing to climate change remains elusive. By combining regional air chemistry model simulations with near-surface observations, we found that anthropogenic emission changes contributed to approximately 23% of the increase in maximum daily 8-h average O concentrations in the BTH region in June-July-August (JJA) 2017 (compared with that in 2013).

Mercury Uptake, Accumulation, and Translocation in Roots of Subtropical Forest: Implications of Global Mercury Budget.

Plant roots are responsible for transporting large quantities of nutrients in forest ecosystems and yet are frequently overlooked in global assessments of Hg cycling budgets. In this study, we systematically determined the distribution of total Hg mass and its stable isotopic signatures in a subtropical evergreen forest to elucidate sources of Hg in plant root tissues and the associated translocation mechanisms. Hg stored in roots and its isotopic signatures show significant correlations to those found in surrounding soil at various soil depths.

Tracing fossil fuel CO by C in maize leaves in Guanzhong Basin of China.

Quantifying fossil fuel CO (CO) in the atmosphere provides a benchmark method to monitor anthropogenic carbon emissions. Radiocarbon (C) in atmospheric CO has been widely studied using the C in plants to document regional CO patterns. However, annual CO variations, reflecting spatial distributions based on plant samples, are still scarce.

Why is the air humid during wintertime heavy haze days in Beijing?

Atmospheric humidity has been shown to promote haze formation, but it remains unclear why the air is humid during heavy haze days in winter. Here we combine water vapor isotope measurements with WRF-Chem simulations to elucidate increasing humidity with aggravation of haze during wintertime in urban Beijing. The vapor isotopic analysis in Beijing shows that the combustion-derived water (CDW) constitutes 11.

Microbial metabolic limitation and carbon use feedback in lead contaminated agricultural soils.

Potentially toxic elements (PTEs) pollution causes a great threat to microbial metabolism, which plays a vital role in studying soil nutrient cycling and predicting carbon (C) storage in agroecosystems. However, the responses of microbial metabolism characteristic to heavy metal contamination and the mechanisms through which microbial metabolism mediate nutrient cycling and C dynamics in contaminated soil remain elusive. Here, we performed an incubation experiment over 80 days to investigate the variations in microbial metabolic limitation under various Pb levels (0, 100, 500, 800, 1500, 2000, and 3000 mg Pb kg dry soil) in cropland soil using extracellular enzymatic stoichiometry, and to reveal the impact of Pb stress on soil C storage by associating with microbial metabolic quotients (qCO) and C use efficiency (CUE).

Microplastics addition reduced the toxicity and uptake of cadmium to Brassica chinensis L.

The coexistence of microplastics (MPs) and toxic metal contaminants in soils is becoming increasingly common, thereby posing serious threat to soil-plant systems. Cadmium (Cd) is the most common metal contaminant in soil and can easily combine with MPs, thereby altering its bioavailability. However, few studies have focused on the co-pollution of MPs and Cd, particularly the complex phytotoxicity caused by their interaction and the effect of co-exposure on Cd uptake in plants.

Sedimentary records of human activities in China over the past two millennia and implications for the Anthropocene: A review.

Human activities have profoundly transformed the natural environment and the Earth system, leading to the concept of the Anthropocene. This paper summarizes the effects of human activities on the environment in China as recorded in sedimentary archives. China is divided into core and marginal areas based on their natural and societal conditions, and changes in selected proxies for four stages since 2.

A critical analysis of sources, pollution, and remediation of selenium, an emerging contaminant.

Selenium (Se) is an essential metalloid and is categorized as emerging anthropogenic contaminant released to the environment. The rise of Se release into the environment has raised concern about its bioaccumulation, toxicity, and potential to cause serious damages to aquatic and terrestrial ecosystem. Therefore, it is extremely important to monitor Se level in environment on a regular basis.

Nitrogen fertilization weakens the linkage between soil carbon and microbial diversity: A global meta-analysis.

Soil microbes make up a significant portion of the genetic diversity and play a critical role in belowground carbon (C) cycling in terrestrial ecosystems. Soil microbial diversity and organic C are often tightly coupled in C cycling processes; however, this coupling can be weakened or broken by rapid global change. A global meta-analysis was performed with 1148 paired comparisons extracted from 229 articles published between January 1998 and December 2021 to determine how nitrogen (N) fertilization affects the relationship between soil C content and microbial diversity in terrestrial ecosystems.

Insight into spatial-temporal patterns of hydroclimate change on the Chinese Loess Plateau over the past 250 years, using new evidence from tree rings.

The climate aridity since the mid-20th century has raised concerns about water resources on the Chinese Loess Plateau (CLP). A lack of extended observation-like precipitation records for the eastern CLP (ECLP) means that it remains unclear whether or not the current arid state of the CLP is unprecedented, and the spatial-temporal characteristics of hydroclimatic variability across the CLP over past centuries are not well understood. Here we present a regional hydrological-year precipitation reconstruction for the Heichashan Mountains, which successfully captures hydroclimate changes on the ECLP since 1773 CE.

Dissociation of Mercuric Oxides Drives Anomalous Isotope Fractionation during Net Photo-oxidation of Mercury Vapor in Air.

The atmosphere is the primary medium for long-distance transport and transformation of elemental mercury (Hg), a potent neurotoxin. The recent discovery of mass-independent fractionation (MIF) of even-mass Hg isotopes (even-MIF, measured as ΔHg and ΔHg) in the atmosphere is surprising and can potentially serve as a powerful tracer in understanding Hg biogeochemistry. Far-ultraviolet (UVC) light-induced gas-phase reactions have been suspected as a likely cause for even-MIF, yet the mechanism remains unknown.

Lake metabolic processes and their effects on the carbonate weathering CO sink: Insights from diel variations in the hydrochemistry of a typical karst lake in SW China.

The precipitation of carbonate minerals does not invariably result in CO emission to the atmosphere, because dissolved inorganic carbon (DIC) can be partially utilized by terrestrial aquatic phototrophs, thus generating an autochthonous organic carbon (AOC) sink. However, little is known about the potential effects of this mechanism on carbon cycles in DIC-rich lakes, mainly due to the lack of detailed documentation of the related processes, which limits our ability to accurately evaluate and predict the magnitude of this carbon sink. We conducted field observations in Fuxian Lake, a large and representative karst lake in the Yunnan-Guizhou Plateau, SW China.

Comparison of black carbon, primary and secondary brown carbon light absorption and direct solar absorption at the foothill and summit of Mt. Hua, China.

Atmospheric black carbon (BC), primary and secondary brown carbon (BrC and BrC) are the light-absorbing carbonaceous aerosol components. The vertical changes in the BC and BrC distributions are not generally known. Here, we presented a study of the spectral light absorption properties, direct solar absorption, and potential source areas of BC and BrC at the foothill (375 m a.

Heterogeneous iodine-organic chemistry fast-tracks marine new particle formation.

The gas-phase formation of new particles less than 1 nm in size and their subsequent growth significantly alters the availability of cloud condensation nuclei (CCN, >30-50 nm), leading to impacts on cloud reflectance and the global radiative budget. However, this growth cannot be accounted for by condensation of typical species driving the initial nucleation. Here, we present evidence that nucleated iodine oxide clusters provide unique sites for the accelerated growth of organic vapors to overcome the coagulation sink.

Sequestration of heavy metals in soil aggregates induced by glomalin-related soil protein: A five-year phytoremediation field study.

Glomalin-related soil protein (GRSP) is an essential bioactive component that may respond to heavy metal stress; however, its exact influence on metal bioavailability and the associated mechanism remains poorly understood. This study investigated the speciation and distribution of heavy metals in soil aggregates associated with GRSP through macroscopic and microscopic approaches. A field study showed that the metal ions were distributed to the macro-aggregate fraction by partitioning the particle size classes during phytoremediation.

Afforestation can lower microbial diversity and functionality in deep soil layers in a semiarid region.

Afforestation is an effective approach to rehabilitate degraded ecosystems, but often depletes deep soil moisture. Presently, it is not known how an afforestation-induced decrease in moisture affects soil microbial community and functionality, hindering our ability to understand the sustainability of the rehabilitated ecosystems. To address this issue, we examined the impacts of 20 years of afforestation on soil bacterial community, co-occurrence pattern, and functionalities along vertical profile (0-500 cm depth) in a semiarid region of China's Loess Plateau.

Molecular characteristics and stable carbon isotope compositions of dicarboxylic acids and related compounds in wintertime aerosols of Northwest China.

Dicarboxylic acids are one of the important water-soluble organic compounds in atmospheric aerosols, causing adverse effects to both climate and human health. More attention has therefore been paid to organic acids in aerosols. In this study, the molecular distribution and diurnal variations of wintertime dicarboxylic acids in a rural site of Guanzhong Plain, Northwest China, were explored.

Ultra-Sensitive Determination of Particulate, Gaseous Inorganic and Organic Iodine-129 and Iodine-127 in Ambient Air.

Atmospheric iodine cycling is of significance in climate change and environmental and health impacts. To better explore speciation transformation of atmospheric stable and radioactive iodine, an ultra-sensitive analytical method was established for determination of I and I in particulate, gaseous inorganic, and gaseous organic species, which was conducted with a self-designed cascade sampling apparatus, followed by their separation with a pyrolysis system and accelerator mass spectrometry and ICP-MS measurements. Combustion protocols for three sampling matrices and NaOH concentration for iodine trapping were optimized to achieve a safe analytical procedure with a high chemical yield of iodine.

Production-Based and Consumption-Based Accounting of Global Cropland Soil Erosion.

The effective control of cropland soil erosion is urgent for all countries because of its threat to global food security. Cropland soil erosion is caused by agricultural production and driven indirectly by consumption. Analyzing the causes and preventive strategies from the consumption side is essential for soil erosion control.

High stability of autochthonous dissolved organic matter in karst aquatic ecosystems: Evidence from fluorescence.

Biological carbon pump (BCP) in karst areas has received intensive attention for years due to their significant contribution to the global missing carbon sink. The stability of autochthonous dissolved organic matter (Auto-DOM) produced by BCP in karst aquatic ecosystems may play a critical role in the missing carbon sink. However, the source of dissolved organic matter (DOM) in inland waters and its consumption by planktonic bacteria have not been thoroughly examined.

A large contribution of methylsiloxanes to particulate matter from ship emissions.

The chemical and stable carbon isotopic composition of the organic aerosol particles (OA) emitted by a shuttle passenger ship between mainland Naples and island Capri in Italy were investigated. Various methylsiloxanes and derivatives were found in particulate ship emissions for the first time, as identified in the mass spectra of a thermal desorption - proton transfer reaction - mass spectrometer (TD-PTR-MS) based on the natural abundance of silicon isotopes. Large contributions of methylsiloxanes to OA (up to 59.

Mercury drives microbial community assembly and ecosystem multifunctionality across a Hg contamination gradient in rice paddies.

Soil microbial communities are critical for maintaining terrestrial ecosystems and fundamental ecological processes. Mercury (Hg) is a heavy metal that is toxic to microorganisms, but its effects on microbial community assembly and ecosystem multifunctionality in rice paddy ecosystems remain largely unknown. In the current study, we analyzed the microbial community structure and ecosystem multifunctionality of paddy soils across a Hg contamination gradient.

Effect of Environmental pH on Mineralization of Anaerobic Iron-Oxidizing Bacteria.

Freshwater lakes are often polluted with various heavy metals in the Anthropocene. The iron-oxidizing microorganisms and their mineralized products can coprecipitate with many heavy metals, including Al, Zn, Cu, Cd, and Cr. As such, microbial iron oxidation can exert a profound impact on environmental remediation.