Carbonaceous aerosol, including organic carbon (OC) and elemental carbon (EC), has significant influence on human health, air quality and climate change. Accurate measurement of carbonaceous aerosol is essential to reduce the uncertainty of radiative forcing estimation and source apportionment. The accurate separation of OC and EC is controversial due to the charring of OC. Therefore, the development of reference materials (RM) for the validation of OC/EC separation is an important basis for further study. Previous RMs were mainly based on ambient air sampling, which could not provide traceability of OC and EC concentration. To develop traceable RMs with known OC/EC contents, our study applied an improved aerosol generation and mixing technique, providing uniform deposition of particles on quartz filters. To generate OC aerosol with similar pyrolytic property of ambient aerosol, both water soluble organic carbon (WSOC) and water insoluble organic carbon (WIOC) were used, and amorphous carbon was selected for EC surrogate. The RMs were analyzed using different protocols. The homogeneity within the filter was validated, reaching below 2%. The long -term stability of RMs has been validated with RSD ranged from 1.7%-3.2%. Good correlation was observed between nominal concentration of RMs with measured concentration by two protocols, while the difference of EC concentration was within 20%. The results indicated that the newly developed RMs were acceptable for the calibration of OC and EC, which could improve the accuracy of carbonaceous aerosol measurement. Moreover, the laboratory-generated EC-RMs could be suitable for the calibration of equivalent BC concentration by Aethalometers. (c) 2024 The Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences. Published by Elsevier B.V. This is an open access article under the CC BY-NC-ND license ( http://creativecommons.org/licenses/by-nc-nd/4.0/ )

Substituting alternative materials and energy sources with forest biomass can cause significant environmental consequences, such as alteration in the released emissions which can be described by displacement factors (DFs). Until now, DFs of wood-based materials have included greenhouse gas (GHG) emissions and have been associated with lower fossil and process-based emissions than non-wood counterparts. In addition to GHGs, aerosols released in combustion processes, for example, alter radiative forcing in the atmosphere and consequently have an influence on climate. In this study, the objective was to quantify the changes in the most important aerosol emission components for cases when wood-based materials and energy were used to replace the production of high-density polyethylene (HDPE) plastic, common fossil-based construction materials (concrete, steel and brick), non-wood textile materials and energy produced by fossil fuels and peat. For this reason, we expanded the DF calculations to include aerosol emissions of total suspended particles (TSP), respirable particulate matter (PM10), fine particles (PM2.5), black carbon (BC), nitrogen oxides (NOx), sulphur dioxide (SO2) and non-methane volatile organic compounds (NMVOCs) based on the embodied energies of materials and energy sources. The DFs for cardboard implied a decrease in BC, SO2 and NMVOC emissions but an increase in the other emission components. DFs for sawn wood mainly indicated higher emissions of both particles and gaseous emissions compared to non-wood counterparts. DFs for wood-based textiles demonstrated increased particle emissions and reduced gaseous emissions. DFs for energy biomass mainly implied an increase in emissions, especially if biomass was combusted in small-scale appliances. Our main conclusion highlights the critical need to thoroughly assess how using forest biomass affects aerosol emissions. This improved understanding of the aerosol emissions of the forestry sector is crucial for a comprehensive evaluation of the climate and health implications associated with forest biomass use.

New soils formed after glacier retreat can provide insights into the rates of soil formation in the context of accelerated warming due to climate change. Recently deglacierized terrains (since the Little Ice Age) are subject to weathering and pedogenesis, and freshly exposed sediments are prone to react readily with the environment. This study aims to determine the impact of parent material and time on soil physical and chemical properties of nine proglacial landscapes distributed in the Tropical Andes and Alps. A total of 188 soil samples were collected along chronosequences of deglacierization and from sites that differed in terms of parent material and classified following three parent material groups: (1) Granodiorite-Tonalite (GT), (2) Gneiss-Shales-Schists (GSS), and (3) Mont-Blanc Granite (MBG). We determined physical and chemical soil properties such as contents of clay, silt, sand, organic carbon, bulk density (BD), pH, extractable cation (exCa, exMg, exK), elemental composition by Xray fluorescence (Al, Si, P, S, K, Ca, Mn, Fe, Cu, Zn, As, Mo, Hg, Pb) and ICP-MS (Al, Ca, Cu, Fe, K, Mg, Mn, Mo, Na, P, S, Zn), and mineral phase (XRD diffraction analysis). Parent material-controlled particle-size distribution, SOC, pH, available P, exCa, and exMg, whereas time since deglacierization only affected SOC and P, and exMg globally. Most of the significant differences in soil properties between parent material groups occurred within the first 17 years after deglacierization, and then we observed a homogenization between sites. While the higher SOC and P contents observed within the GT Andean sites might be due to the parent material composition leading to faster initial soil formation, we identified potential As, Cu, Mo, and Mn toxicity within those soils. Our study highlights the need to investigate further proglacial soil's buffering capacity and carbon sequestration to globally inform the conservation and management of novel proglacial ecosystems.

In cold regions, the frozen soil-rock mixture (FSRM) is subjected to cyclic loading coupled with freeze-thaw cycles due to seismic loading and ambient temperature changes. In this study, in order to investigate the dynamic mechanical response of FSRM, a series of cyclic cryo-triaxial tests were performed at a temperature of -10 degrees C on FRSM with different coarse-grained contents under different loading conditions after freeze-thaw cycles. The experimental results show that the coarse-grained contents and freeze-thaw cycles have a significant influence on the deformation properties of FSRM under cyclic loading. Correspondingly, a novel binary-medium-based multiscale constitutive model is firstly proposed to describe the dynamic elastoplastic deformation of FSRM based on the coupling theoretical framework of breakage mechanics for geomaterials and homogenization theory. Considering the multiscale heterogeneities, ice-cementation differences, and the breakage process of FSRM under external loading, the relationship between the microscale compositions, the mesoscale deformation mechanism (including cementation breakage and frictional sliding), and the macroscopic mechanical response of the frozen soil is first established by two steps of homogenization on the proposed model. Meanwhile, a mixed hardening rule that combines the isotropic hardening rule and kinematic hardening is employed to properly evaluate the cyclic plastic behavior of FSRM. Finally, comparisons between the predicted results and experimental results show that the proposed multiscale model can simultaneously capture the main feature of stress-strain (nonlinearity, hysteresis, and plastic strain accumulation) and volumetric strain (contraction and dilatancy) of the studied material under cyclic loading.

The radiative forcing of soot is dependent on the morphology, mixing state and structure. Cloud processing has been predicted to affect their mixing properties but little is known about the resulting light absorption properties. We collected ambient particles in the pre-cloud period, the cloud residues and interstitials in the in-cloud period at Mt. Tianjing (southern China). The morphology parameters of soot aggregates with varying mixing materials [sulfate (S) and organics (OM)] and mixing structures were investigated by a transmission electron microscope, and their absorption cross were calculated based on discrete dipole approximation. We found that the number contribution of soot-S decreased from 45% in the pre-cloud period to 32% in the in-cloud period, and that of soot-OM increased from 44% to 60%. Moreover, the number proportion of soot-OM with fully embedded structure increased remarkably in the in-cloud period (29%), compared with that in the pre-cloud period (3%). In addition, the soot-S aggregates became denser after in-cloud aqueous process. However, for soot-OM aggregates, the morphology remained relatively constant. The distinctly different change of soot-S and soot-OM in morphology highlights the chemically resolved reconstruction of soot morphology. Theoretical calculation further shows that the changes of soot particles in the mixing state and morphological characteristics by the cloud process resulted in the light absorption enhancement increase from 1.57 to 2.01. This study highlights that the evolution of microphysical properties upon cloud processing should also be considered in climate models to more accurately evaluate the impacts of soot particles.

The risk of carbon emissions from permafrost is linked to an increase in ground temperature and thus in particular to thermal insulation by vegetation, soil layers and snow cover. Ground insulation can be influenced by the presence of large herbivores browsing for food in both winter and summer. In this study, we examine the potential impact of large herbivore presence on the soil carbon storage in a thermokarst landscape in northeastern Siberia. Our aim in this pilot study is to conduct a first analysis on whether intensive large herbivore grazing may slow or even reverse permafrost thaw by affecting thermal insulation through modifying ground cover properties. As permafrost soil temperatures are important for organic matter decomposition, we hypothesize that herbivory disturbances lead to differences in ground-stored carbon. Therefore, we analyzed five sites with a total of three different herbivore grazing intensities on two landscape forms (drained thermokarst basin, Yedoma upland) in Pleistocene Park near Chersky. We measured maximum thaw depth, total organic carbon content, delta C-13 isotopes, carbon-nitrogen ratios, and sediment grain-size composition as well as ice and water content for each site. We found the thaw depth to be shallower and carbon storage to be higher in intensively grazed areas compared to extensively and non-grazed sites in the same thermokarst basin. First data show that intensive grazing leads to a more stable thermal ground regime and thus to increased carbon storage in the thermokarst deposits and active layer. However, the high carbon content found within the upper 20 cm on intensively grazed sites could also indicate higher carbon input rather than reduced decomposition, which requires further studies including investigations of the hydrology and general ground conditions existing prior to grazing introduction. We explain our findings by intensive animal trampling in winter and vegetation changes, which overcompensate summer ground warming. We conclude that grazing intensity-along with soil substrate and hydrologic conditions-might have a measurable influence on the carbon storage in permafrost soils. Hence the grazing effect should be further investigated for its potential as an actively manageable instrument to reduce net carbon emission from permafrost.

Artificial glacier melt reduction is gaining increasing attention because of rapid glacier retreats and the projected acceleration of future mass losses. However, quantifying the effect of artificial melt reduction on glaciers in China has not been currently reported. Therefore, the case of Urumqi Glacier No.1 (eastern Tien Shan, China) is used to conduct a scientific evaluation of glacier cover efficiency for melt reduction between 24 June and 28 August 2021. By combining two high-resolution digital elevation models derived from terrestrial laser scanning and unmanned aerial vehicles, albedo, and meteorological data, glacier ablation mitigation under three different cover materials was assessed. The results revealed that up to 32% of mass loss was preserved in the protected areas compared with that of the unprotected areas. In contrast to the unprotected glacier surface, the nanofiber material reduced the glacier melt by up to 56%, which was significantly higher than that achieved by geotextiles (29%). This outcome could be attributed to the albedo of the materials and local climate factors. The nanofiber material showed higher albedo than the two geotextiles, dirty snow, clean ice, and dirty ice. Although clean snow had a higher albedo than the other materials, its impact on slowing glacier melt was minor due to the lower snowfall and relatively high air temperature after snowfall in the study area. This indicates that the efficiencies of nanofiber material and geotextiles can be beneficial in high-mountain areas. In general, the results of our study demonstrate that the high potential of glacier cover can help mitigate issues related to regions of higher glacier melt or lacking water resources, as well as tourist attractions.

Aerosols generated from aqueous samples of readily obtainable humic material standards are often used as proxies for organic particulates found in the atmosphere in various investigations, such as consideration of radiative forcing effects. Here, we present results for the retrieved complex index of refraction, m = n + ik, at a wavelength of 403 nm for aerosols prepared from six humic material standards using a calibrated cavity ring-down spectrometer: a humic acid sodium salt, Pahokee peat humic and fulvic acids, Elliott soil humic and fulvic acids, and Suwannee river fulvic acid. In addition, we have conducted UV-vis spectrometric studies to measure the mass absorption coefficients, molar absorptivities, and absorption Angstrom exponents of bulk aqueous solutions of the humic materials. We find clear differences between the humic acid (HA) and fulvic acid (FA) samples with the HA having larger values for the imaginary part of the refractive index, k. The mean value for the HA samples is k = 0.170 while the mean is k = 0.037 for the FA materials. We have examined correlations between the retrieved refractive index and humic material characteristics obtained from spectroscopic and elemental analysis, including aromatic content and the oxygen-to-carbon atomic ratio, where the molar absorption coefficient yields the strongest correlation. Finally, we compare the humic material optical properties to those of authentic and laboratory generated organic carbon samples in order to assess the usefulness of these humic standards as proxies for light absorbing aerosol.

Through the cooperative efforts of the Scientific Committee on Antarctic Research (SCAR) Evolution and Biodiversity in Antarctica (EBA) Project and the Latitudinal Gradient Project (LGP), a monitoring network was established in Victoria Land in 2002 to assess the impacts of climate change on vegetation, soils, active-layer dynamics, and permafrost across a latitudinal gradient. In this study, we report on the key factors influencing soil development across the gradient, including vegetation, parent material characteristics, and climate. Physical and chemical soil properties at depths of 2-8 and 10-20 cm were investigated at 7 sites and on 14 permanent plots from Apostrophe Island in Northern Victoria Land (73 degrees 30'S, 167 degrees 50'E) to Granite Harbour in Southern Victoria Land (77 degrees 00'S, 162 degrees 26'E) along the Ross Sea coast. The relationships among vegetation, parent material, and regional climate and soil properties were tested with Principal Component Analyses. There were no significant correlations or relationships in soil properties across the climate gradient. In fact, local microclimatic appears to be more effective than the regional gradient in influencing the properties. Microclimate was also important relative to active-layer depth and vegetation distribution. Lithology was strongly related to several chemical parameters, notably extractable Al, Fe, Ca, K, but was unrelated to grain-size distribution. Vegetation was related to the chemistry of the surface-soil layer, including nitrate, organic carbon, C/N ratio and water content, and also the active-layer depth. Penguins had the greatest influence on soil properties in initiating the development of ornithogenic soils. Further analyses on soil properties, including a greater number of sites, will be required to represent more extensively the lithological variability and to extend the latitudinal extremes of the gradient. The results presented here are an important reference for future monitoring activities in Victoria Land. (c) 2007 Elsevier B.V. All rights reserved.