Influence Of Black Carbon Research Articles

Long-term effects of ambient PM2.5 constituents on metabolic syndrome in Chinese children and adolescents

Metabolic syndrome (MetS) is considered a main public health issue as it remarkably adds the risk of cardiovascular disease, leading to a heavy burden of disease. There is growing evidence linking fine particulate matter (PM2.5) exposure to MetS. However, the influences of PM2.5 constituents, especially in children and adolescents, remain unclear. Our study was according to a national analysis among Chinese children and adolescents to examine the associations between long-term exposure to PM2.5 main constituents and MetS. A total of 10,066 children and adolescents aged 10–18 years were recruited in 7 provinces in China, with blood tests, health exams, and questionnaire surveys. We estimated long-term exposures to PM2.5 mass and its five constituents, containing black carbon (BC), organic matter (OM), inorganic nitrate (NO3−), sulfate (SO42−), and soil particles (SOIL) from multi-source data fusion models. Mixed-effects logistic regression models were used with the adjustment of a variety of covariates. In the surveyed populations, 2.9% were classified as MetS. From the single-pollutant models, we discovered that long-term exposures to PM2.5 mass, BC, OM, NO3−, as well as SO42−, were significantly associated with the prevalence of MetS, with odds ratios (ORs) per 1 μg/m3 that were 1.02 (95% confidence interval (CI): 1.01, 1.03) for PM2.5 mass, 1.24 (95% CI: 1.14, 1.35) for BC, 1.07 (95% CI: 1.04, 1.11) for OM, 1.09 (95% CI: 1.04, 1.13) for NO3−, and 1.14 (95% CI:1.04, 1.24) for SO42−. The influence of BC on the prevalence of MetS was robust in both the multi-pollutant model and the PM2.5-constituent joint model. The paper indicates long-term exposure to PM2.5 mass and specific PM2.5 constituents, particularly for BC, was significantly associated with a higher MetS prevalence among children and adolescents in China. Our results highlight the significance of establishing further regulations on PM2.5 constituents.

Explaining the natural and anthropogenic factors driving glacier recession in Kashmir Himalaya, India.

Glaciers across the Kashmir Himalayan region are melting at an accelerated pace compared to other regions across the Himalayan arc. This study analyzed the recession patterns of nine glaciers in the Kashmir Himalaya region over 28years between 1992 and 2020 using satellite images and field measurements. The recession patterns were correlated with debris cover, topographic factors, and ambient black carbon (BC) concentration at glacier sites. HYSPLIT model was used to track the air mass sources at a 7-day time-step from September 1, 2014, to September 28, 2014, over the selected region. All nine glaciers revealed high recession as indicated by changes in the area (average recession: 20.8%) and snout position (~ 14m a-1). The relative percentage of debris on each glacier varied between ~ 0% (clean glacier) and 43%. Although the investigated glaciers lie in the same climatological regime, their topographical behavior is dissimilar with mean altitude ranging between 4000 and ~ 4700m asl and the average slope varying from 17 to 24°. All the investigated glaciers are north-facing except G3 (southerly aspect). Our results indicate anomalously high ambient BC concentrations, ranging from 500 to 1364ngm-3, at the glacier sites, higher than previously studied for glaciers in the Himalayas and neighboring Tibetan Plateau. The backward air-mass trajectory modeling indicated both local and global sources of particulate matter in the study area. A comparative analysis of BC measurements and glacier recession with the studies conducted across high Asia indicated the influence of BC in accelerating the melting of glaciers in the Kashmir region.

Bimodal distribution of size-resolved particle effective density: results from a short campaign in a rural environment over the North China Plain

Abstract. Effective density is one of the most important physical properties of atmospheric particles. It is closely linked to particle chemical composition and morphology and could provide special information on particle emissions and aging processes. In this study, size-resolved particle effective density was measured with a combined differential mobility analyzer–centrifugal particle mass analyzer–condensation particle counter (DMA–CPMA–CPC) system in autumn 2019 as part of the Multiphase chemistry experiment in Fogs and Aerosols in the North China Plain (McFAN). With a newly developed flexible Gaussian fit algorithm, frequent (77 %–87 %) bimodal distribution of particle effective density is identified, with a low-density mode (named sub-density mode) accounting for 22 %–27 % of the total number of observed particles. The prevalence of the sub-density mode is closely related to fresh black carbon (BC) emissions. The geometric mean for the main density mode (ρ‾eff,main) increases from 1.18 ± 0.10 g cm−3 (50 nm) to 1.37 ± 0.12 g cm−3 (300 nm) due to a larger fraction of high-density components and a more significant restructuring effect at large particle sizes but decreases from 0.89 ± 0.08 g cm−3 (50 nm) to 0.62 ± 0.12 g cm−3 (300 nm) for the sub-density mode (ρ‾eff,sub), which could be mainly ascribed to the agglomerate effect of BC. ρ‾eff,main and ρ‾eff,sub show similar diurnal cycles with peaks in the early afternoon, mainly attributed to the increasing mass fraction of high material density components associated with secondary aerosol production, especially of secondary inorganic aerosol (SIA). To investigate the impact of chemical composition, bulk particle effective density was calculated based on measured chemical composition (ρeff,ACSM) and compared to the average effective density at 300 nm (ρ‾eff,tot,300nm). The best agreement between the two densities is achieved when assuming a BC effective density of 0.60 g cm−3. The particle effective density is highly dependent on SIA and BC mass fractions. The influence of BC on the effective density is even stronger than SIA, implying the importance and necessity of including BC in the estimate of effective density for ambient particles.

Aerosol influence on the pre-monsoon rainfall mechanisms over North-East India: A WRF-Chem study

The importance of aerosols and absorbing aerosols in influencing weather is well recognized. This study is carried out over North-East (NE) India during the pre-monsoon season, during which the region experiences the highest atmospheric heating due to high loading of absorbing aerosols. The region, also a biodiversity hotspot, has observed a decreasing rainfall trend in this season. Previous aerosol-rainfall studies over India have mostly focused on the monsoon season, but pre-monsoon rainfall also is an important rainfall component for this region. This study includes the results of a modelling study carried out with WRF-Chem model to investigate how aerosols impact the pre-monsoon rainfall and their mechanisms over this region. The influence of black carbon (BC) on radiation, clouds, rainfall and rainfall characteristics has also been investigated. The study shows that aerosols induce changes in cloud amounts which relates to rainfall changes. The semi-direct effect was found to be responsible for cloud reduction below 2 km altitude, thus affecting mainly lower-level clouds. Aerosol radiative feedbacks affected rainfall according to the height of the terrain in the region and tended to increase and decrease rainfall in general over low and high-terrain areas, respectively. Aerosol effects suppressed rainfall for more duration than it caused enhancement. The effect of increasing black carbon emissions showed a consistent increase in moisture in the region but also a consistent reduction in clouds, the changes in the spatial distribution of which was also related to the rainfall changes. BC caused suppression of lower intensity and enhancement of higher intensity rainfall. These results help to understand better the effects of aerosols on pre-monsoon rainfall distributions and the mechanisms involved.

Analysis of the Effect of Optical Properties of Black Carbon on Ozone in an Urban Environment at the Yangtze River Delta, China

Black carbon (BC) reduces the photolysis coefficient by absorbing solar radiation, thereby affecting the concentration of ozone (O3) near the ground. The influence of BC on O3 has thus received much attention. In this study, Mie scattering and the tropospheric Ultraviolet and Visible radiation model are used to analyze the effect of BC optical properties on radiation. Combined with data of O3 precursors in Nanjing in 2014, an EKMA curve is drawn, and the variations in O3 concentration are further investigated using a zero-dimensional box mechanism model (NCAR MM). When O3 precursors are unchanged, radiation and O3 show a highly similar tendency in response to changing BC optical properties (R=0.997). With the increase of modal radius, the attenuation of fresh BC to radiation and O3 first trends upward before decreasing. In the mixing process, the attenuation of BC to radiation and O3 presents an upward tendency with the increase of relative humidity but decreases rapidly before increasing slowly with increasing thickness of coating. In addition, mass concentration is another major factor. When the BC to PM2.5 ratio increases to 5% in Nanjing, the radiation decreases by approximately 0.13%–3.71% while O3 decreases by approximately 8.13%–13.11%. The radiative effect of BC not only reduces O3 concentration but also changes the EKMA curve. Compared with the NOx control area, radiation has a significant influence on the VOCs control area. When aerosol optical depth (AOD) increases by 17.15%, the NOx to VOCs ratio decreases by 8.27%, and part of the original NOx control area is transferred to the VOCs control area.

Spatio-temporal variations of absorbing aerosols and their relationship with meteorology over four high altitude sites in glaciated region of Pakistan

In high Asia, absorbing aerosols, particularly black carbon (BC) and dust, reportedly have strong effects on glaciers and the hydrological cycle. Knowledge about influence of BC over Hindukush-Karakoram-Himalaya (HKH) region in northern Pakistan is limited and therefore, required in-depth investigation. This study reports on the ground based BC and satellite based aerosol variations during the period 2016–2017, over four high altitude stations, including Astore, Gilgit, Sost, and Skardu, representing HKH range in northern Pakistan. Hourly, daily, and monthly variations of BC aerosol were examined in relation to meteorology. BC aerosols exhibited diurnal variations with sharp morning and evening peaks. During the study period BC concentrations were in the range of 0.9–6.1 μg/m3 over the study locations. During the study period, the average BC concentration over Astore, Gilgit, Sost and Skardue were 2.6 ± 0.7, 3.7 ± 0.6, 2.1 ± 1.1 and 3.0 ± 1.0 μg/m3, respectively. AOD varies from 0.01 to 0.16 and AI ranges from 0.2 to 5.5 during the study period. BC aerosols exhibited positive correlations with temperature and wind speed, in addition to a negative correlation with relative humidity. BC also has a positive correlation with AOD and AI. The long range transport of aerosols to the receptor sites were from central Asia, Eastern Europe, Middle East and India as well.

Assessing the relationship and influence of black carbon on distribution status of organochlorines in the coastal sediments from Pakistan

Levels of total organic carbon (TOC) and black carbon (BC) were determined together with those of organochlorine pesticides (OCPs) and polychlorinated biphenyls (PCBs) in the selected eighteen coastal sites (n = 285) along the Arabian Sea from Pakistan. Results showed that the total concentration of TOC, BC, ∑OCPs and ∑26PCBs ranged between 0.3 and 2.9% dw, 0.1–0.2% dw, 0.9–110 ng g−1 dw and 6.2–1200 ng g−1 dw, respectively. Correlation analysis of BC (r = 0.26–0.89) and TOC (r = 0.06–0.69) revealed a stronger association with studied compounds. The sedimentary depositional fluxes (D) for ∑OCPs and ∑26PCBs were calculated as 1.7 and 4.9 tons yr−1, respectively. In the coastal belt of Pakistan, sedimentary mass inventories (I) indicated the presence of 13 and 37 metric tons of ∑OCPs and ∑26PCBs, respectively.

The Influence of Black Carbon on the Sorption and Desorption of Two Model PAHs in Natural Soils

Black carbons (BC) which result from the incomplete combustion of farm waste [man-made (burned) BC] are highly absorbent. In Taiwan, the burning of farm waste known as slash and burn is common. The BCs from the burning may present an environmental challenge. Little is known about the effect of BCs on the transport of hydrophobic organic contaminants (HOC). This study investigates the sorption of anthracene and naphthalene to BCs in soil and efficiency of the surfactants Tween 80 and Triton X-100 in their removal. Both surfactants demonstrated 2-6 times increased solubility in the soils with the addiction of BC. Column experiments were performed to imitate the transportation of these contaminants in groundwater through soils before and after adding BC produced by burning farm waste in the lab. We found significantly increased sorption of anthracene in soil added with BCs produced in the lab, suggesting that fraction of organic carbon (foc) can contribute to sorption of such HOCs. Sorption of naphthalene was increased but not significantly. Comparing the concentrations of contaminants, we found the soil containing BC from burned farm waste absorbed HOC more efficiently than the organic BC (naturally-occurring) in the original soil. Therefore, sorption capacity and influence on the transport of HOC cannot be estimated simply by the foc of the soil because the two BCs differ greatly in their sorption ability. BC from farm waste absorbs more contaminants than naturally occurring BC in the soil.

Historical Trends of Atmospheric Black Carbon on Tibetan Plateau As Reconstructed from a 150-Year Lake Sediment Record

Black carbon (BC) is one of the key components causing global warming. Especially on the Tibetan Plateau (TP), reconstructing BC's historical trend is essential for better understanding its anthropogenic impact. Here, we present results from high altitude lake sediments from the central TP. The results provide a unique history of BC over the past 150 years, from the preindustrial to the modern period. Although BC concentration levels in the Nam Co Lake sediments were lower than those from other high mountain lakes, the temporal trend of BC fluxes clearly showed a recent rise, reflecting increased emissions from anthropogenic activities. The BC records were relatively constant until 1900, then began to gradually increase, with a sharp rise beginning around 1960. Recent decades show about 2.5-fold increase of BC compared to the background level. The emission inventory in conjunction with air mass trajectories further demonstrates that BC in the Nam Co Lake region was most likely transported from South Asia. Rapid economic development in South Asia is expected to continue in the next decades; therefore, the influence of BC over the TP merits further investigations.

Explaining differences between bioaccumulation measurements in laboratory and field data through use of a probabilistic modeling approach

In the regulatory context, bioaccumulation assessment is often hampered by substantial data uncertainty as well as by the poorly understood differences often observed between results from laboratory and field bioaccumulation studies. Bioaccumulation is a complex, multifaceted process, which calls for accurate error analysis. Yet, attempts to quantify and compare propagation of error in bioaccumulation metrics across species and chemicals are rare. Here, we quantitatively assessed the combined influence of physicochemical, physiological, ecological, and environmental parameters known to affect bioaccumulation for 4 species and 2 chemicals, to assess whether uncertainty in these factors can explain the observed differences among laboratory and field studies. The organisms evaluated in simulations including mayfly larvae, deposit-feeding polychaetes, yellow perch, and little owl represented a range of ecological conditions and biotransformation capacity. The chemicals, pyrene and the polychlorinated biphenyl congener PCB-153, represented medium and highly hydrophobic chemicals with different susceptibilities to biotransformation. An existing state of the art probabilistic bioaccumulation model was improved by accounting for bioavailability and absorption efficiency limitations, due to the presence of black carbon in sediment, and was used for probabilistic modeling of variability and propagation of error. Results showed that at lower trophic levels (mayfly and polychaete), variability in bioaccumulation was mainly driven by sediment exposure, sediment composition and chemical partitioning to sediment components, which was in turn dominated by the influence of black carbon. At higher trophic levels (yellow perch and the little owl), food web structure (i.e., diet composition and abundance) and chemical concentration in the diet became more important particularly for the most persistent compound, PCB-153. These results suggest that variation in bioaccumulation assessment is reduced most by improved identification of food sources as well as by accounting for the chemical bioavailability in food components. Improvements in the accuracy of aqueous exposure appear to be less relevant when applied to moderate to highly hydrophobic compounds, because this route contributes only marginally to total uptake. The determination of chemical bioavailability and the increase in understanding and qualifying the role of sediment components (black carbon, labile organic matter, and the like) on chemical absorption efficiencies has been identified as a key next steps.

Influence of black carbon and chemical planarity on bioavailability of sediment‐associated contaminants

Black carbon (BC) and chemical properties may play a significant role in defining the bioavailability of hydrophobic organic compounds (HOCs) in sediment. In the current study, bioavailability of four HOCs with differing planarity was determined in sediments amended with two types of BC (soot and charcoal) at different concentrations by matrix solid-phase microextraction (matrix-SPME) and bioaccumulation testing using the freshwater oligochaete Lumbriculus variegatus. Furthermore, the applicability of the matrix-SPME method to bioavailability estimation in BC-amended sediment was tested. The charcoal treatment significantly reduced the bioaccumulation of the planar compounds (3,3',4,4'-tetrachlorobiphenyl and benzo[a]pyrene) in L. variegatus, and the matrix-SPME method showed a similar trend as contaminant bioaccumulation in L. variegatus. Conversely, manipulation of sediment with soot had no effect or slightly increased bioavailability of the planar compounds in both bioaccumulation and matrix-SPME tests. Little if any affect was noted in bioavailability of the nonplanar compounds (2,2',4,4',5,5'-hexachlorobiphenyl and permethrin) with the soot and charcoal amendments. Results showed that the role of BC in defining bioavailability of HOCs depends not only on the type and concentrations of BC present, but also the planarity of the HOCs.

Black carbon-dominated PCDD/Fs sorption to soils at a former wood impregnation site

The influence of black carbon (BC) on the sorption of 17 native polychlorinated-p-dibenzodioxins (PCDDs) and polychlorinated dibenzofurans (PCDFs) was studied in five soil samples from a sawmill site where wood used to be impregnated with chlorophenol preservatives. The presence of BC caused measured total organic carbon (TOC)–water distribution ratios (KTOC) to be a median factor of 51 (interquartile range 18–68, n=85) higher than modeled amorphous organic carbon (AOC)–water distribution ratios (KAOC). KTOC was a factor of 73±27 above KAOC for PCDFs (n=10) and a factor of 20±13 (n=7) for PCDDs. The reason for this difference is probably that attaining a planar configuration after sorption to BC is less thermodynamically favorable for PCDDs than for PCDFs. BC–water distribution ratios were calculated from KTOC, KAOC and BC contents, and ranged from 109.9 (2,3,7,8-Tetra-CDD) to 1011.5lkg−1 (Octa-CDF). More than 90% of the PCDD/Fs in the soil was calculated to be BC-sorbed. Dissolved organic carbon (DOC)–water distribution ratios were measured to be in the same order of magnitude as KAOC. This study shows that strong sorption to BC should be included when assessing ecotoxicological risk or modeling transport to groundwater of PCDD/Fs in soil.

The influence of black carbon on the crystallization point of salt aerosol

The influence of black carbon on the crystallization point of salt aerosol