One attraction of using hydrochar (HC) and biochar (BC) in soil is their intrinsic affinity for organic contaminants. Oxidative ageing is likely to induce changes in physicochemical properties and functionality. To explore the long-term potential trajectories for corn stalk HC and BC to adsorb organic pollutants, we employed HC and BC exposure in 5% H2O2 to simulate oxidative ageing and get insights into mechanisms of atrazine adsorption on fresh and artificially aged materials. The physicochemical properties of fresh and aged materials were systematically compared using elemental analysis, SSA, FTIR, XPS and SEM-EDS, alongside K2Cr2O7/H2SO4 treatment to assess chemical oxidation stability. Atrazine is a typical herbicide chemical and hydrophobic organic pollutant. Adsorption isotherms of atrazine were used to reveal differences in mechanisms of sorption to BC and HC, by assessment before and ageing. BC freshly produced at 650 °C displayed higher capacity for atrazine sorption than BC produced at 500 °C, with a dominant role for π-π EDA interactions. The sorption capacity of HC freshly produced at 250 °C was higher than for HC produced at 200 °C HC, owing to higher C content and atrazine partitioning into the organic phase. Ageing increased the surface abundance of oxygenated functional groups for BC and HC and diminished bulk aromaticity. After ageing, atrazine sorption by high temperature BC was lower, but for HC it was increased. Such divergent effects must be considered when developing strategies to co-manage contaminants and carbon through the addition of carbonized materials to land.

The effect of long-term nitrogen (N) and sulfur (S) deposition on litter mass loss and changes in carbon (C), N, and S composition and enzyme activities during litter decomposition was investigated in a boreal forest. This study included four N × S treatments: control (CK), N application (30 kg N ha−1 yr−1), S application (30 kg S ha−1 yr−1), and N plus S application (both at 30 kg ha−1 yr−1). Two experiments were conducted for 22 months: 1) a common litter decomposition experiment with litter bags containing a common litter (same litter chemistry) and 2) an in-situ litter decomposition experiment with litter from each treatment plot (and thus having different litter chemistry). Litterbags were placed onto the four treatment plots to investigate the direct effect of N and S addition and the combined effect of N and/or S addition and litter chemistry on litter decomposition, respectively. Regardless of the source of litter, N and/or S addition affected C, N and S composition at a certain period of the experiment but did not affect litter mass loss and enzyme activity throughout the experiment, indicating that the N and S addition rates were below the critical level required to affect C and N cycling in the studied ecosystem. However, the greater change in N composition per unit of litter mass loss in the N addition treatment than in the other treatments in the common litter but not in the in-situ litter experiment, suggests that the effect of N addition on N loss and retention depends on the initial litter chemistry. We conclude that the studied N and S addition rates did not affect litter decomposition and elemental cycling in the studied forest ecosystem even though the N and S addition rates were much greater than their ambient deposition rates.

In this study, we present the development of a mobile system to measure real-world total respiratory tract deposition of inhaled ambient black carbon (BC). Such information can be used to supplement the existing knowledge on air pollution-related health effects, especially in the regions where the use of standard methods and intricate instrumentation is limited. The study is divided in two parts. Firstly, we present the design of portable system and methodology to evaluate the exhaled air BC content. We demonstrate that under real-world conditions, the proposed system exhibit negligible particle losses, and can additionally be used to determine the minute ventilation. Secondly, exemplary experimental data from the system is presented. A feasibility study was conducted in the city of La Paz, Bolivia. In a pilot experiment, we found that the cumulative total respiratory tract deposition dose over 1-h commuting trip would result in approximately 2.6 μg of BC. This is up to 5 times lower than the values obtained from conjectural approach (e.g. using physical parameters from previously reported worksheets). Measured total respiratory tract deposited BC fraction varied from 39% to 48% during walking and commuting inside a micro-bus, respectively.To the best of our knowledge, no studies focusing on experimental determination of real-world deposition dose of BC have been performed in developing regions. This can be especially important because the BC mass concentration is significant and determines a large fraction of particle mass concentration. In this work, we propose a potential method, recommendations, as well as the limitations in establishing an easy and relatively cheap way to estimate the respiratory tract deposition of BC.

Preoxidation of As(III) to As(V) is required for the efficient removal of total arsenic in the treatment of wastewater. In this work, the electro-Fenton oxidation of As(III) with a high efficiency was successfully achieved by using the system of the stainless steel net (SSN) coating with reduced graphene oxide (RGO@SSN) as the cathode and stainless steel net (SSN) as the sacrificial anode. The RGO@SSN was synthesized by electrophoretic deposition-annealing method. The carbon disorder and defects of RGO resulted from the remained oxygen-containing functional groups facilitated the electrocatalytically active sites for two-electron oxygen reduction reaction (ORR). A high concentration (up to 1000 μmol/L) of H₂O₂ was in-situ produced through two-electron oxygen reduction reaction of electro-catalysis, and then served as the electro-Fenton reagent for the oxidation of As(III). HO generated by H₂O₂ participating the electro-Fenton reaction or decomposed at the surface of RGO@SSN cathode at acid condition endowed the strong oxidizing ability for As(III). The electro-Fenton equipped with RGO@SSN cathode has a promising application in the oxidation and removal of organic or inorganic pollutants in wastewater.

Black carbon (BC) can combine with organic matter and form secondary pollutants known as aged BC. BC and aged BC can cause respiratory system inflammation and induce lesions at relevant sites, but the underlying mechanism has remained unknown. To gain insight into the potential mechanisms, we focused on macrophages and transforming growth factor β-activated kinase 1 (TAK1) which are a crucial factor in inflammation. Our research aims to determine the role of TAK1 in macrophages in pulmonary inflammation induced by particulate matter. In this study, BC and 1,4-naphthoquinone were mixed to model aged BC (1,4NQ-BC) in atmosphere. BC induced mice lung inflammation model, lung macrophage knock-down TAK1 animal model and primary macrophage knock-down TAK1 model were used to explore whether TAK1 in macrophage is a critical role in the process of inflammation. The results showed that the expressions of inflammatory cytokines (IL-1β, IL-6, IL-33) mRNA were significantly increased and the phosphorylation of MAPK and NF-κB signaling pathway related proteins were enhanced in RAW 264.7 cell lines. In vivo studies revealed that the indicators of pulmonary inflammation (pathology, inflammatory cell numbers) and related cytokines (IL-1β, IL-6, IL-33) mRNA expressions in CD11c-Map3k7⁻/⁻ animals were significantly lower than wild-type animals after mice were instilled particles. In mice primary macrophages, the expressions of IL-6, IL-33 mRNA were inhibited after TAK1 gene was knock-down. These results unequivocally demonstrated that TAK1 plays a crucial role in BC induced lung inflammation in mice, and we can infer that BC and 1,4NQ-BC cause these inflammatory responses by stimulating pulmonary macrophages.

Nitrogen (N) addition can change physicochemical properties and biogeochemical processes in soil, but whether or not these changes further affect the transport and transformation of heavy metal speciation is unknown. Here, a long-term (2004–2016) field experiment was conducted to assess the responses of different heavy metal speciation in three soil aggregate fractions to N additions in a temperate agroecosystem of North China. The organic matter turnover time was quantified based on changes in δ13C following the conversion from C3 (wheat) to C4 crop (corn). Averagely, N addition decreases and increases the heavy metal contents in bioavailable and organic bound fractions by 27.5% and 16.6%, respectively, suggesting N addition promotes the transformation of heavy metal speciation from bioavailable to organic bound, and such a promotion in a small aggregate fraction is more remarkable than that in a large aggregate fraction. The transformations of heavy metal speciation from bioavailable to organic bound in all soil aggregate fractions are largely dependent on the increments in the turnover time of organic matter. The increase in organic matter turnover time induced by N addition may inhibit the desorption of heavy metals from organic matter by prolonging the interaction time between heavy metals and organic matter and enhance the capacity of organic matter to adsorb heavy metals by increasing the humification degree and functional group. Our work can provide insights into the accumulation, migration, and transformation of heavy metals in soils in the context of increasing global soil N input from a microenvironmental perspective.

We analyzed paired serum, urine, and hair samples from 94 Korean children and adults to investigate levels of 11 perfluoroalkyl acids (PFAAs). The effects of demographic factors and dietary habits on PFAA exposure were also assessed based on the paired samples. The total PFAA concentrations were 2.4–31 ng/mL in serum, not detected–9.5 ng/mL in urine, and 0.48–15 ng/g in hair. Levels of perfluoropentanoic acid (PFPeA) and perfluorohexanoic acid (PFHxA), which have short carbon chains, were 1.5–5 fold higher in urine and hair than in serum. The PFAA concentrations in serum exhibited a decreasing trend with age from young childhood to adolescence, followed by an increasing trend after adolescence. For most PFAA species, concentrations in serum were higher in adult males than in adult females (p < 0.01). No sex difference was evident in the urine and hair samples. In addition, there was no age difference in the urine samples, but in the hair samples, we observed higher concentrations of PFAAs in children than in the other age groups (p < 0.01). The consumption rates of fish and water showed significant correlations with serum (positive correlation) and hair (negative) concentrations, respectively. No relationships between serum and hair/urine levels for most PFAAs were observed, except between serum and hair levels for perfluorooctanoic acid (PFOA).

This work presents the main results of two experimental campaigns carried out in summer and winter seasons in a complex pollution hotspot near a large park, El Retiro, in Madrid (Spain). These campaigns were aimed at understanding the microscale spatio-temporal variation of ambient concentration levels in areas with high pollution values to obtain data to validate models on the effect of urban trees on particulate matter concentrations.Two different measuring approaches have been used. The first one was static, with instruments continuously characterizing the meteorological variables and the particulate matter concentration outside and inside the park. During the summer campaign, the particulate matter concentration was clearly influenced by a Saharan dust outbreak during the period 23 June to 10 July 2016, when most of the particulate matter was in the fraction PM₂.₅₋₁₀. During the winter campaign, the mass concentrations were related to the meteorological conditions and the high atmospheric stability.The second approach was a dynamic case with mobile measurements by portable instruments. During the summer campaign, a DustTrak instrument was used to measure PM₁₀ and PM₂.₅ in different transects close to and inside the park at different distances from the traffic lane. It was observed a decrease in the concentrations up to 25% at 20 m and 50% at 200 m. High PM₁₀ values were linked to dust resuspension caused by recreational activities and to a Saharan dust outbreak. The highest PM values were measured at the Independencia square, an area with many bus stops and high traffic density. During the winter campaign, three microaethalometers were used for Black Carbon measurement. Both pollutants also showed a reduction in their concentrations when moving towards inside the park. For PM₁₀ and PM₂.₅, reductions up to 50% were observed, while for BC this reduction was smaller, about 20%.

The imprints of fireworks displays on the adjacent water body were investigated from the perspective of cogeneration of black carbon, metals and perchlorate (ClO₄⁻). In particular, the mixing and dissipation of ClO₄⁻ were studied at Oak Lake, Lincoln, Nebraska, following fireworks displays in 2015 and 2016. Following the display, ClO₄⁻ concentration in the water increased up to 4.3 μg/L and 4.0 μg/L in 2015 and 2016, respectively. A first-order model generally provided a good fit to the measured perchlorate concentrations from which the rate of dissipation was estimated as 0.07 d⁻¹ in 2015 and 0.43 d⁻¹ in 2016. SEM images show imprints of soot and metal particles in aerosol samples. EDS analysis of the lake sediment confirmed the presence of Si, K, Ca, Zn and Ba, most of which are components of fireworks. The δ¹³C range of −7.55‰ to −9.19‰ in the lake water system closely resembles fire-generated carbon. Cogeneration of black carbon and metal with perchlorate was established, indicating that ClO₄⁻ is an excellent marker of fireworks or a burning event over all other analyzed parameters. Future microcosmic, aggregation and column-based transport studies on black carbon in the presence of perchlorate and metals under different environmental conditions will help in developing transport and fate models for perchlorate and black carbon particles.

A comprehensive spatio-vertical survey of short-chain (SCCPs, C10-13) and medium-chain (MCCPs, C14-17) chlorinated paraffins (CPs) was performed in surface and core soils from Chinese nation-wide agricultural lands in 2016, and a total of 48 congener groups were measured. The shorter carbon chain C10-11 in SCCP and C14-15 in MCCP homologue groups, and the lower chlorinated congeners (Cl5-7) for both CP groups were predominant. The ∑SCCP and ∑MCCP concentrations in surface soils ranged from 39 to 1609 ng/g and 127–1969 ng/g, dry weight (dw), respectively. The spatial distribution trend showed that SCCP congener groups with relatively low octanol-water partition coefficient (KOW) and octanol-air partition coefficient (KOA) are uniformly distributed across surface soils compared to MCCP congener groups. Significant relationships were observed between the spatial variation of SCCP concentrations and the driving factors responsible for dispersion and deposition. The distribution behavior of SCCPs and MCCPs in highland and plain surface soils showed an increasing trend of MCCP concentrations with elevation, indicating the “mountain cold-trapping effect”. Vertical distribution profile revealed similar homologue group composition patterns of SCCP and MCCP congener groups as those of surface soils. Furthermore, the penetration potential ratios (r) of chlorine and carbon atoms of CPs demonstrated that the lower chlorinated (Cl5-7) and the shorter carbon chain (C10-13) congener groups are more prone to vertical movement into deeper soil layers compared to the longer carbon chain (C14-17) and highly chlorinated (Cl8-10) congener groups.