Traffic-loaded areas have been of increasing concern due to the potential risk of carcinogenic pollutants, including antimony (Sb), which accumulates mostly in atmospheric particles (PM) and can ...interact with soil organic matter (Corg). The stability of Sb in topsoils was studied via the adsorption mechanism using standard soils and Corg-reach vehicle-produced particles as the unique source of “traffic” Sb. The mixed adsorbents were prepared from loamy sand and clay standard soils, and braking abrasion dust and diesel engine soot as Sb sources in atmospheric PM. Whereas the black carbon (BC), as part of Corg, disposes of exceptional adsorption properties compared to the other Corg, all adsorption experiments were performed identically on the adsorbents prepared from the original standard soils and Sb source materials and on the adsorbents prepared from the same materials annealed at 375 °C to ensure only BC participation in adsorption processes. The concentration of the Sb model solution corresponded to the average Sb content in rainwater from traffic-loaded localities. In addition to Sb, the Corg and iron (Fe) were monitored. The sorbability of Sb on the loamy sand soil mixtures increased up to 90% compared with the pure soil due to new active surface sites for Sb binding created due to the Corg added with the source material. The clay soil mixture containing 10 times more Corg compared with the loamy sand soil accumulated the Corg from the source material, which resulted in blocking active sites and a decline in Sb sorbability by up to 20%. The processes performed identically with original and annealed materials showed the same trends and confirmed the key role of BC and soil quality in the accumulation and stability of Sb in traffic-loaded topsoils. The participation of Fe in Sb surface interactions was not observed.
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•Antimony (Sb) near traffic nodes represents environmental risk due to growing automotive traffic.•Brake abrasion dust poses actual Sb risk through atmospheric particles (PM) and following infiltration into local topsoils.•Black carbon (BC) plays key role in Sb interaction with organic matter (OM) in soils and PM.•Stability of Sb near traffic nodes is entirely controlled by topsoil texture and BC content.
In order to investigate associations between air pollution and adverse health effects consistent fine spatial air pollution surfaces are needed across large areas to provide cohorts with comparable ...exposures. The aim of this paper is to develop and evaluate fine spatial scale land use regression models for four major health relevant air pollutants (PM2.5, NO2, BC, O3) across Europe.
We developed West-European land use regression models (LUR) for 2010 estimating annual mean PM2.5, NO2, BC and O3 concentrations (including cold and warm season estimates for O3). The models were based on AirBase routine monitoring data (PM2.5, NO2 and O3) and ESCAPE monitoring data (BC), and incorporated satellite observations, dispersion model estimates, land use and traffic data. Kriging was performed on the residual spatial variation from the LUR models and added to the exposure estimates. One model was developed using all sites (100%). Robustness of the models was evaluated by performing a five-fold hold-out validation and for PM2.5 and NO2 additionally with independent comparison at ESCAPE measurements. To evaluate the stability of each model's spatial structure over time, separate models were developed for different years (NO2 and O3: 2000 and 2005; PM2.5: 2013).
The PM2.5, BC, NO2, O3 annual, O3 warm season and O3 cold season models explained respectively 72%, 54%, 59%, 65%, 69% and 83% of spatial variation in the measured concentrations. Kriging proved an efficient technique to explain a part of residual spatial variation for the pollutants with a strong regional component explaining respectively 10%, 24% and 16% of the R2 in the PM2.5, O3 warm and O3 cold models. Explained variance at fully independent sites vs the internal hold-out validation was slightly lower for PM2.5 (65% vs 66%) and lower for NO2 (49% vs 57%). Predictions from the 2010 model correlated highly with models developed in other years at the overall European scale.
We developed robust PM2.5, NO2, O3 and BC hybrid LUR models. At the West-European scale models were robust in time, becoming less robust at smaller spatial scales. Models were applied to 100 × 100 m surfaces across Western Europe to allow for exposure assignment for 35 million participants from 18 European cohorts participating in the ELAPSE study.
•Robust PM2.5, NO2, BC and O3 hybrid LUR models at a 100x100 m resolution for Western Europe were developed•Models included large scale SAT and CTM estimates and fine scale traffic and land use and were further improved with kriging•Models were robust in time at European scale, becoming less robust at smaller spatial scales.
The seasonal variability of black carbon (BC) aerosols in India is studied using high resolution (10 km) BC simulations conducted using the Weather Research and Forecasting Model coupled with ...Chemistry. The model reproduces the observed seasonality of surface BC fairly well over most parts of India but fails to capture the seasonality in the Himalayas and deviates from the observed BC magnitude at several sites. The errors in modeled BC are attributed to uncertainties in BC emissions and their diurnal cycle, planetary boundary layer height underestimation, and aerosol processes. Model results show distinct but opposite seasonality of BC in the lower (LT) and free troposphere (FT) with BC showing winter maximum and summer minimum in the LT and vice versa in the FT. Our analysis shows that BC seasonality is not driven by seasonality of the anthropogenic emissions but by changes in the regional meteorology through weakening of the horizontal transport and strengthening of the vertical transport of BC during summertime compared to winter. BC in both the LT and FT comes mostly from anthropogenic emissions followed by biomass burning emissions except during winter when long‐distant sources become more important in the FT. BC in the FT is significantly affected by anthropogenic emissions from all parts of India. The source‐receptor relationship changes seasonally, but the regional transport remains a significant contributor to BC loadings in the LT of India, highlighting the necessity of considering nonlocal sources along with local emissions when designing strategies for mitigating BC impacts on air quality.
Key Points
Black carbon shows opposite seasonal cycle in the lower and free troposphere
The seasonal cycle of BC is driven mainly by seasonal changes in meteorology
Regional transport significantly impact BC distribution
Rapid industrial development and human activities have caused a degradation of soil quality and fertility. There is increasing interest in rehabilitating low fertility soils to improve crop yield and ...sustainability. Biochar, a carbonaceous material intentionally produced from biomass, is widely used as an amendment to improve soil fertility by retaining nutrients and, potentially, enhancing nutrient bioavailability. But, biochar is not a simple carbon material with uniform properties, so appropriate biochar selection must consider soil type and target crop. In this respect, many recent studies have evaluated several modification methods to maximize the effectiveness of biochar such as optimizing the pyrolysis process, mixing with other soil amendments, composting with other additives, activating by physicochemical processes, and coating with other organic materials. However, the economic feasibility of biochar application cannot be neglected. Strategies for reducing biochar losses and its application costs, and increasing its use efficiency need to be developed. This review synthesized current understanding and introduces holistic and practical approaches for biochar application to low fertility soils, with consideration of economic aspects.
•Biochar has potential to be the best management practice for low fertility soils.•Biochar coating with organic materials can result in enhanced crop nutrient supply.•Biochar may accelerate the composting process and improve the end-product quality.•The influence of biochar varies strongly according to the types of feedstock/soil.
Black carbon is a product of the incomplete combustion of carbonaceous fuels and has significant adverse effects on climate change, air quality, and human health. China has been a major contributor ...to global anthropogenic black carbon emissions. This study develops a black carbon inventory in China, using 2015 as the base year, and projects annual black carbon emissions in China for the period 2016–2050, under two scenarios: a Reference scenario and an Accelerated Reduction scenario. The study estimates that the total black carbon emissions in China in 2015 were 1100 thousand tons (kt), with residential use being the biggest contributor, accounting for more than half of the total black carbon emissions, followed by coke production, industry, agricultural waste burning, and transportation. This study then projects the total black carbon emissions in China in 2050 to be 278 kt in the Reference scenario and 86 kt in the Accelerated Reduction Scenario. Compared to the Reference scenario, the Accelerated Reduction scenario will achieve much faster and deeper black carbon reductions in all the sectors. The dramatic reductions can be attributed to the fuel switching in the residential sector, faster implementation of high-efficiency emission control measures in the industry, transportation, and coke production sectors, and faster phase-out of agricultural waste open burning. This analysis reveals the high potential of black carbon emission reductions across multiple sectors in China through the next thirty years.
Atmospheric black carbon concentrations were measured at two urban sites (Mexico City and Monterrey), one suburban site (Juriquilla) and one high-altitude site (Altzomoni) in Mexico during 2015 and ...part of 2016. Black carbon concentrations were compared against other criteria gases finding a strong correlation with carbon monoxide at the urban sites. The carbon monoxide-black carbon correlation for the Mexico City site is 0.77. Urban sites had an average black carbon concentration of above 2.5 μg m−3, the suburban site 0.75 μg m−3, and the high-altitude site 0.27 μg m−3. Compared to other studies, the average levels are comparable, and the urban and suburban locations showed a trend towards increased atmospheric black carbon concentrations at year end. Other urban places (Guadalajara, Cuernavaca, and Iztapalapa) reported black carbon concentrations, but for less than a year. For the first time, a Latin-American country (Mexico) measured black carbon continuously at several sites for a year applying the same data quality assurance.
•Atmospheric black carbon is measured at two urban sites, one suburban site and one high-altitude site in Mexico during 2015.•Black carbon concentrations reported could become part of a baseline for future mitigation policies to reduce emissions.•Urban sites had average black carbon concentration above 2.5, the suburban site 0.75, and the high-altitude site 0.27 µg m-3.−3.•This is the first time that a Latin-American country measured black carbon continuously at several sites.
Previous studies indicated that using CO2 as a reaction agent in the pyrolysis of biomass led to an enhanced generation of syngas via direct reaction between volatile organic carbons (VOCs) evolved ...from the thermal degradation of biomass and CO2. In addition, the physico-chemical properties of biochar in CO2 were modified. In this current study, biochars generated from red pepper stalks in N2 and CO2 (RPS-N and RPS-C, respectively) were tested for their effects on the immobilization of Pb, Cd, Zn, and As in contaminated soils. Soils were incubated for one month with 2.5% of RPS, and two biochars (i.e., RPS-N and RPS-C) at 25°C. After the incubation period soils were analyzed to determine the amendment effects on the behavior of metal(loid)s. The potential availability and mobility kinetics of metal(loid)s were assessed by single extraction of ammonium acetate and consecutive extraction of calcium chloride, respectively. Sequential extraction was used to further examine potential changes in geochemical fractions of metal(loid)s. The increased soil pH induced by application of the biochars reduced the potentially available Pb, Cd, and Zn, while RPS-C significantly reduced Pb due to the high surface area and aromaticity of RPS-C. However, RPS-C mobilized potentially available As compared to RPS-N due to the increased soil pH. Biochars reduced the mobility kinetics of Pb, Cd, and Zn, and RPS-N effectuated the greatest reduction of As mobility. The RPS-C increased the Fe and Mn oxides, hydroxide, and organically bound Pb, while both biochars and RPS-N increased residual Cd and Zn, and organically bound As, respectively. When considering the two biochars, RPS-C was highly effective for immobilization of Pb in soils, but it had no effect on Cd and Zn and a negative effect on As. In addition, RPS-C significantly increased the total exchangeable cations in soils.
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•Biochars markedly reduced Cd, Pb and Zn mobility in soils.•Biochar pyrolyzed in CO2 most effectively immobilized Pb.•Biochar pyrolyzed in CO2 increases As mobility more.•More siloxane groups present in biochar pyrolysed in CO2.
Black carbon (BC), pyrogenic residues resulting from the incomplete combustion of organics, are liberated from wildfires at high rates. Subsequent introduction to aqueous environments via atmospheric ...deposition or overland flow results in the formation of a dissolved fraction, called dissolved black carbon (DBC). As wildfire frequency and intensity increases along with a changing climate, it becomes imperative to understand the impact a concurrent increase in DBC load might have to aquatic ecosystems. In the atmosphere BC stimulates warming by absorbing solar radiation, and similar processes may occur with surface waters that contain DBC. In this work we investigated whether the addition of environmentally relevant levels of DBC could impact surface water heating dynamics in experimental settings. DBC was quantified at multiple locations and depths in Pyramid Lake (NV, USA) during peak fire season while two large, proximal wildfires burned. DBC was detected in Pyramid Lake water at all sampled locations at concentrations (3.6–18 ppb) significantly higher than those reported for other large inland lakes. DBC was positively correlated (R2 = 0.84) with chromophoric dissolved organic matter (CDOM) but not bulk dissolved or total organic carbon (DOC, TOC), suggesting that DBC is a significant component of the optically active organics in the lake. Subsequent lab-based experiments were conducted by adding environmentally relevant levels of DBC standards to pure water, exposing the system to solar spectrum radiation, and creating a numerical model of heat transfer based on observed temperatures. The addition of DBC at environmentally relevant orders of magnitude caused reductions to shortwave albedo when exposed to the solar spectrum, which resulted in 5–8 % more incident radiation being absorbed by water and changes to water heating dynamics. In environmental settings, this increase in energy absorption could translate to increased heating of the epilimnion in Pyramid Lake and other wildfire-impacted surface waters.
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•High levels of dissolved black carbon were detected in a wildfire-impacted lake.•Dissolved black carbon correlated to optically active organics in the lake.•Dissolved black carbon caused accelerated water heating in lab experiments.•Wildfire-derived dissolved black carbon may impact surface water heating dynamics.
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