[Changes in Health Risks and Pollution Sources of Atmospheric PM2.5-bound Metals in a Background Site in North China].

To explore the change features of PM2.5-bound metals in a background site of North China in the past ten years, 71 and 160 samples were collected from December 2011 to January 2013 (period Ⅰ) and from September 2019 to November 2021 (period Ⅱ) in Tuoji Island National Atmospheric Monitoring Station, respectively.The concentration of metals sampled was determined using ICP-MS, and the concentrations, sources, and health risks of heavy metals were compared. The results revealed that the average concentration of PM2.5 was (54.06±39.71) µg·m-3during period Ⅱ, which was 3.53 ng·m-3 lower than that during period Ⅰ. The concentrations of Zn, Mn, As, Pb, and V in stage Ⅱ decreased by 54.53, 172.63, 0.8, 79.06, and 3.81 ng·m-3, respectively, whereas the concentrations of Cr, Cu, Cd, and Ni increased by 2.01, 5.42, 3.03, and 3.55 ng·m-3, respectively. The PMF model results indicated that the biggest contributor to PM2.5-bound metal was industrial emissions (32.32%), followed by coal combustion (27.47%), vehicle emissions (23.70%), ship emissions (9.69%), and dust sources (6.83%) during period Ⅱ. The contribution ratio of dust sources and ship emissions decreased by 20.73% and 8.83%, respectively, whereas for coal combustion and industrial emissions it increased by 2.50% and 13.52%, respectively, when compared with that during period Ⅰ. The total carcinogenic risk induced by PM2.5-bound heavy metals of period Ⅱ increased, with the highest contributions by Cr and Cd. The total non-carcinogenic risk decreased, with Mn contributing the most. Therefore, in the process of air pollution control, the control of pollution sources of heavy metals such as Cr and Mn should be reinforced.

Treatment of particle/gas partitioning using level III fugacity models in a six-compartment system.

In this paper, two level III fugacity models are developed and applied using an environmental system containing six compartments, including air, aerosols, soil, water, suspended particulate matters (SPMs), and sediments, as a "unit world". The first model, assumes equilibrium between air and aerosols and between water and SPMs. These assumptions lead to a four-fugacity model. The second model removes these two assumptions leading to a six-fugacity model. The two models, compared using four PBDE congeners, BDE-28, -99, -153, and -209, with a steady flux of gaseous congeners entering the air, lead to the following conclusions. 1. When the octanol-air partition coefficient (KOA) is less than 1011.4, the two models produce similar results; when KOA > 1011.4, and especially when KOA > 1012.5, the model results diverge significantly. 2. Chemicals are in an imposed equilibrium in the four-fugacity model, but in a steady state and not necessary an equilibrium in the six-fugacity model, between air and aerosols. 3. The results from the six-fugacity model indicate an internally consistent system with chemicals in steady state in all six compartments, whereas the four-fugacity model presents an internally inconsistent system where chemicals are in equilibrium but not a steady state between air and aerosols. 4. Chemicals are mass balanced in air and aerosols predicted by the six-fugacity model but not by the four-fugacity model. If the mass balance in air and aerosols is achieved in the four-fugacity model, the condition of equilibrium between air and aerosols will be no longer valid.

New equation to predict size-resolved gas-particle partitioning quotients for polybrominated diphenyl ethers.

Gas/particle (G/P) partition quotients of semi-volatile organic compounds (SVOCs) for bulk air have been widely discussed in experimental and theoretical contexts, but research on size-resolved G/P partition quotients (KPi) are scarce and limited in scope. To investigate G/P partition behavior of polybrominated diphenyl ethers (PBDEs) for size-segregated particles in the atmosphere, 396 individual size-segregated particulate samples (36 batches × 11 size-ranges), and 108 pairs of concurrent gaseous and bulk particulate samples were collected in Harbin, China. A steady-state equation based on bulk particles is derived to determine G/P partition quotients of PBDEs for size-segregated particles, which depends on the organic matter contents of size-segregated particles (fOMi). This equation can well predict KPi with knowledge of bulk partition quotient (KPS), ambient temperature, and fOMi, the results of which match well with monitoring data in Harbin and other published data collected in Shanghai and Guangzhou of China and Thessaloniki of Greece, and remedies a defect of over-estimate KPi for high-brominated PBDEs by the previous equation. In particular, the new equation contributes to obtaining the PBDEs concentrations in all atmospheric phase from partial phase, then provides a credible path to evaluate healthy exposure dose from the airborne PBDEs, by co-utilization with exposure models.

Seasonal variation and influence factors of organophosphate esters in air particulate matter of a northeastern Chinese test home.

To investigate the seasonal variation of organophosphate esters (OPEs) in air particulate matter (PM) and the corresponding influence factors in indoor environment, 104 indoor PM samples were collected in a test home, Harbin, China, from March 2017 to March 2018. The Σ12OPEs concentrations ranged from 0.41 ng/m3 to 940 ng/m3. Tris(1-chloro-2-propyl) phosphate (TCIPP) was the most abundant OPE and accounted for 83.2% of the total OPEs. The Σ12OPEs concentrations in spring and summer were higher than those in autumn and winter. Outdoor total suspended particles (TSP) were the main factor that affected the concentration variation of OPEs in PM samples in the test home. Comparisons of the gas/particle (G/P) partitioning equilibrium models indicated that the Dachs-Eisenreich (D-E) model estimates were more reliable than the other models in this study. The particle fractions of OPEs with log KOA > 10.51 that predicted by all four models generally well matched the measured OPE particle fractions in the literatures. To OPEs with lower molecular weight, inhalation was the main exposure route and ingestion contributed mostly to OPEs with higher molecular weight. In addition, the estimated daily intakes (EDIs) and carcinogenic risks (CRs) posed by OPEs were all below the recommended values, indicating that the current OPE levels in the test home were within the safe thresholds.

Illicit drugs and their metabolites in 36 rivers that drain into the Bohai Sea and north Yellow Sea, north China.

Illicit drugs and their metabolites have recently been recognized as an emerging group of contaminants due to their potential ecotoxicological impact in aquatic ecosystems. To date, information on the occurrence of these compounds in the aquatic environment of China remains limited. In this study, we collected surface water samples from 36 rivers in north China that discharge into the Bohai Sea and north Yellow Sea and measured the concentrations of amphetamine-like compounds, ketamines, cocainics, and opioids. The occurrence and spatial patterns of these substances show significant differences between the rivers and regions. Two designer drugs, methamphetamine (METH) and ketamine (KET), were the most abundant compounds detected in the entire set of samples (detection frequency of 92 and 69 %). The concentrations of METH and KET ranged from <0.1 to 42.0 ng L(-1) (mean = 4.53 ng L(-1)) and <0.05 to 4.50 ng L(-1) (mean = 0.49 ng L(-1)), respectively. The high detection frequencies of METH and KET are consistent with the fact that they are the main illicit drugs consumed in China. The high concentrations of these illicit drugs and their metabolites were found in areas that have a high population density. The riverine input of total illicit drugs into the Bohai Sea and north Yellow Sea was estimated to be in the range of 684 to 1160 kg per year.

Polycyclic aromatic hydrocarbons in Chinese surface soil: occurrence and distribution.

In this study, 16 polycyclic aromatic hydrocarbons (PAHs) were analyzed in 157 concurrently collected soil samples in 2005 over China. Higher concentration of ∑16PAHs was found in urban soil, followed by rural and background soil. The results indicated that PAHs in Chinese surface soil showed a primary distribution pattern, which was confirmed by the positive correlation with emission inventory. Based on the results of literature over the past 10 years (2004-2013) in China, the spatial distribution of PAHs in urban and rural soil was established. An obvious geographical distribution with PAH concentration was found, as higher in Eastern China and lower in Middle and Western China. Furthermore, PAH pollution in Chinese riverbank soil was summarized and showed higher levels, indicating their potential sources from polluted rivers. According to our knowledge, this is the first time to comprehensively study the PAH pollution status in Chinese surface soil on the national scale based on monitoring results.

[Emission factors of polycyclic aromatic hydrocarbons (PAHs) in residential coal combustion and its influence factors].

As the emission source of polycyclic aromatic hydrocarbons (PAHs), domestic coal combustion has attracted increasing attention in China. According to the coal maturity, combustion form and stove type associated with domestic coal combustion, a large-size, full-flow dilution tunnel and fractional sampling system was employed to collect the emissions from five coals with various maturities, which were burned in the form of raw-coal-chunk (RCC)/honeycomb-coal-briquettes (HCB) in different residential stoves, and then the emission factors of PAHs (EF(PAHs)) were achieved. The results indicate that the EF(PAHs) of bituminous coal ranged from 1.1 mg x kg(-1) to 3.9 mg x kg(-1) for RCC and 2.5 mg x kg(-1) to 21. 1 mg x kg(-1) for HCB, and the anthracite EF(PAH8) were 0.2 mg x kg(-1) for RCC and 0.6 mg x kg(-1) for HCB, respectively. Among all the influence factors of emission factors of PAHs from domestic coal combustion, the maturity of coal played a major role, the range of variance reaching 1 to 2 orders of magnitude in coals with different maturity. Followed by the form of combustion (RCC/HCB), the EF(PAHs) of HCB was 2-6 times higher than that of RCC for the same geological maturity of the coal. The type of stove had little influence on EF(PAHs).

[Concentrations and distribution of organochlorine pesticides in the surface sediments of Jiaozhou Bay, Taozi Bay and Sishili Bay].

Forty-eight surface sediment samples collected from Jiaozhou Bay, Taozi Bay and Sishili Bay were analyzed for organochlorine pesticides (OCPs) by Gas Chromatography. Results showed that average concentrations of HCHs, HCB and DDTs in marine sediments were 0.33, 0.31 and 10.33 ng x g(-1) in Jiaozhou Bay and 0.26, 0.10 and 4.56 ng x g(-1) in Taozi Bay and Sishili Bay, respectively. Contamination status of OCPs was relatively higher in Jiaozhou Bay than in other inland coastal regions, especially for the levels of DDTs; however, OCPs concentrations were relatively low in Taozi Bay and Sishili Bay. The source of HCHs could be mainly attributed to the heavy historical application in agricultural areas and late transport to coastal region through surface runoff or riverine discharge, and DDTs were primarily originated from the use of technical DDTs. Fresh input of lindane and dicofol-type DDTs were found in several sites, such as Qingdao Port. High concentrations of DDTs in Jiaozhou Bay should arouse much attention.

Fugacity approach to evaluate the sediment-water diffusion of polycyclic aromatic hydrocarbons.

Diffusion is an important process for sediment-water exchange and plays a vital role in controlling water quality. Fugacity fraction (ff) was used to estimate the sediment-water diffusion of polycyclic aromatic hydrocarbons (PAHs) between seawater and surficial sediment. A total of 33 surface sediment and sea water samples were collected concurrently from the northeast coastal area in China and 25 PAHs were analyzed including the alkylated and chlorated PAHs. Fugacity fraction was calculated based on the PAH concentrations in water and sediment, octanol-water partition coefficient of PAHs, organic matter content in sediment, and density of sediment. The calculated results showed that ff increased with decreasing molecular weight of PAHs. The low molecular weight PAHs (2-3 rings) transferred from sediment to water and the sediment acted as a secondary source to the water. The medium molecular weight PAHs (4-5 rings) were close to the sediment-water equilibrium and the transfer tendency shifted between sediment and water. The high molecular weight PAHs (5-6 rings) transferred from water into sediment and the sediment acted as a sink. Soot carbon and the difference of PAH concentrations between sediment and water were found to be important factors affecting the sediment-water diffusion. This study provided new insight into the process of sediment-water diffusion, which has a great influence on the quality of water, especially in severely-polluted sediment areas.

Seasonal and spatial variations of air concentrations of polycyclic aromatic hydrocarbons in Northeastern Chinese urban region.

Polyurethane foam disk passive air samplers were deployed along an urban-rural-background transect in a northeastern Chinese region (Harbin) to investigate the spatial and seasonal variations of polycyclic aromatic hydrocarbons (PAHs). The ∑16PAHs concentrations [ng/(sample·day)] were high at urban sites (315 ± 206), followed by rural sites (222 ± 160), suburban site (142 ± 114) and background site (128 ± 107). The urban fractionation effect was observed along the transect with increasing proportions for low molecular weight PAHs and decreasing proportions for high molecular weight PAHs. PAHs were found to be higher in winter and spring than in summer and autumn, most likely due to the combustion of coal and biomass for domestic heating. Sources of PAHs were investigated by principal component analysis in combination with diagnostic ratios, which both indicated that pyrogenic sources were the main sources of PAHs in the air of Harbin, China.

[Gaseous polycyclic aromatic hydrocarbons in Harbin air].

Polyurethane foam passive air samplers (PUF PAS) were fixed at eight sampling sites in Harbin Region concurrently to research atmospheric concentration and distribution of polycyclic aromatic hydrocarbons (PAHs) in Spring of 2007 (January to April). Results showed that the PUF PAS mostly absorbed the 3-4 ring PAHs, which accounted for 91.22%-96.37% comparing to total concentration. Total PAHs concentration had obvious area difference from urban to remote areas, such as 356.49 ng/d for urban, 162.65 ng/d for suburban, 278.35 ng/d for rural and 183.99 ng/d for background, with ratios of urban atmospheric concentration to rural concentration more than 2, three times higher than that of remote area. The atmospheric concentration was significantly affected by sources. Sources of PAHs in air of Harbin Region were investigated by diagnostic ratios, which indicated that coal and biofuel combustion were the main sources of PAHs in air of urban and rural area, respectively. The toxic equivalence factor (TEF) was used for health risk assessment, with similar area difference to concentration distribution, which implying bigger potential heath risk for urban and rural people than other areas. Good reproducibility of PUF passive air sampler was confirmed by one pair of passive samplers deployed at an urban site. The results of the study demonstrated the capability of PUF PAS to monitor atmospheric PAHs in a city scale at the same time.