Search

Leaf hydraulic traits are considered the key determinants of gas exchange and therefore affect species distributions along environmental gradients, but the patterns of leaf hydraulic traits and their associations with gas exchange across altitudinal gradients remain largely unknown.Here, we measured leaf hydraulic traits, gas exchange, leaf anatomical traits and plant size traits in two dominant alpine shrubs (Caragana jubata and Salix gilashanica) across an altitudinal gradient from 3100 to 3700 m.The findings indicated that with increasing altitude, both shrub species exhibited an increase in leaf hydraulic safety (more negative KleafP50), a decrease in leaf hydraulic efficiency (Kleaf‐max) and an increase in intrinsic water use efficiency (WUEi), thus allowing them to adapt to higher altitude habitats. The more negative KleafP50 was associated with a greater ratio of major to minor vein density (VLAmaj/VLAmin), the lower Kleaf‐max was associated with a lower minor vein density (VLAmin) and greater increase in WUEi arose from the small decrease in the photosynthetic rate relative to the stomatal conductance. However, C. jubata was consistent with the 'hydraulic safety strategy' with a great decrease in KleafP50, a small decrease in Kleaf‐max and a small increase in WUEi along with decreasing plant height and leaf area with increasing altitude. Whereas S. gilashanica was consistent with the 'photosynthetic efficiency strategy' with a small decrease in KleafP50, a greater decrease in Kleaf‐max and a greater increase in WUEi along with an increasing plant height and unchanged leaf area with increasing altitude.Overall, these findings provide new insights to improve understanding how shift in leaf hydraulic traits and their associations with gas exchange and plant size allow plants to adapt to high‐altitude habitats. Read the free Plain Language Summary for this article on the Journal blog. [ABSTRACT FROM AUTHOR]

ABSTRACT Determining the differences in flower hydraulic traits and structural resource allocation among closely related species adapted to low mean annual precipitation (MAP) can provide insight into plant adaptation to arid environments. Here, we measured the maximum flower hydraulic conductance (Kmax‐flower), water potential at induction 50% loss of Kmax‐flower (P50‐flower), flower pressure–volume parameters, dry mass of individual flowers and structural components (vexillum, wings, keels, stamens and sepals) of six Caragana species growing in regions ranging from 110 to 1400 mm MAP. Compared with species from high‐MAP environments, those from low‐MAP environments presented lower Kmax‐flower, more negative P50‐flower, osmotic potential at full turgor (πo) and turgor loss points (πtlp), and a greater bulk modulus of elasticity (ε). Consequently, a negative correlation between Kmax‐flower (hydraulic efficiency) and P50‐flower (hydraulic safety) was observed across Caragana species. Furthermore, the dry masses of individual flowers and structural components (vexillum, wings, keels, stamens and sepals) were greater in the species from the low‐MAP environment than in those from the high‐MAP environment. These findings suggest that greater flower hydraulic safety and drought tolerance combined with greater structural resource allocation promote drought adaptation in Caragana species to low‐MAP environments. [ABSTRACT FROM AUTHOR]

Sediment cores from the Dashiwei Tiankeng reach of the Bailang underground river were collected and analyzed for polycyclic aromatic hydrocarbons (PAHs). The concentrations of total PAHs ranged from 35.34 to 280.17 ng/g (mean 107.65 ng/g), and the concentrations of benzo[a]pyrene ranged from 1.78 to 175.74 ng/g (mean 35.94 ng/g). Analyses on molecular markers inferred that the PAHs were sourced mainly from wood and coal combustion before 1998, but there were obvious petroleum and petroleum combustion inputs after 1999. The PAHs profile indicated that the Bailang underground river was polluted by two major events. One was steel smelting in the 1950s, and the other was rapid economic development in the 1990s. The relationship between the PAHs and the sediment organic matter (SOM) in the profile was negative. Factors that impacted the SOM contents in sediment core included vegetation, agriculture crops, wood and fossil fuel burning, and soil erosion caused by construction. The sediment cores from the Bailang underground river reflected the economic development of the region. [ABSTRACT FROM AUTHOR]

Accurate analysis of polycyclic aromatic hydrocarbons (PAHs) in soils remains a challenge due to the complexity of sample matrices. In this paper, phenyl-modified magnetic mesoporous silica (Fe 3 O 4 @mSiO 2 -Ph-PTSA) was synthesized with p-toluenesulfonic acid (PTSA) as the catalyst and used as a selective adsorbent for the clean-up of PAHs extracted from soils. The material prepared without PTSA as the catalyst (Fe 3 O 4 @mSiO 2 -Ph) was synthesized for comparison. The synthesized materials were first systematically characterized and evaluated. It was found that the grafting amount of the phenyl group onto Fe 3 O 4 @mSiO 2 -Ph-PTSA was higher than that onto Fe 3 O 4 @mSiO 2 -Ph. The extraction efficiency obtained by extracting PAHs from the extracted soil matrix solution demonstrated that Fe 3 O 4 @mSiO 2 -Ph-PTSA possessed a much higher extraction efficiency than that of Fe 3 O 4 @mSiO 2 -Ph, which can be attributed to the greater amount of phenyl groups grafted on Fe 3 O 4 @mSiO 2 in the presence of the PTSA catalyst. Moreover, contrast experiments showed that Fe 3 O 4 @mSiO 2 -Ph-PTSA displayed higher selectivity towards PAHs than towards n-alkanes and that the π-π interaction played a key role in the adsorption process. In the presence of the soil extract matrix, the parameters affecting the extraction efficiency of Fe 3 O 4 @mSiO 2 -Ph-PTSA for PAHs were optimized. Under the optimal conditions, coupled with pressurized liquid extraction and gas chromatograph-mass spectrometer, the proposed method for the determination of PAHs in soils was linear in the range of 5–500 ng g −1 , and the correlation coefficients (R) ranged between 0.9994 and 0.9999. The limits of detection (LODs) and limits of quantification (LOQs), which were based on signal-to-noise ratios of 3 and 10, respectively, were in the range of 0.07–0.41 ng g −1 and 0.24–1.37 ng g −1 . The developed method displayed a better clean-up effect than that for silica gel column method, and the matrix effect markedly decreased compared to that of the uncleaned condition. Finally, the developed method was successfully applied for the detection of PAHs in environmental soils, and the data were consistent with the results obtained by the silica gel column method. The analytical results were also consistent with those for the real environment. [ABSTRACT FROM AUTHOR]

N -nitrosamines are a type of nitrogen-containing organic pollutant with high carcinogenicity and mutagenicity. In the main drinking water sources of small and medium-sized towns in China, the contamination levels of N -nitrosamines remain unclear. In addition, there is still lack of research on the concentration of N -nitrosamines and their precursors in tributary rivers. In this study, eight N -nitrosamines and their formation potentials （FPs） were investigated in the Qingjiang River, which is a primary tributary of the Yangtze River. The sewage discharge sites were also monitored, and the environmental influencing factors, carcinogenic and ecological risks caused by N -nitrosamines, and their precursors were evaluated. The results showed that six N -nitrosamines were detected in water samples of the Qingjiang River, among which NDMA [（10 ±15） ng·L -1 ], NDEA [（9.3 ±9.3） ng·L -1 ], and NDBA [（14 ±7.8） ng·L -1 ] were the dominant N -nitrosamines, whereas seven N -nitrosamines were detected in chloraminated water samples, among which NDMA-FP [（46 ±21） ng·L -1 ], NDEA-FP [（26 ±8.3） ng·L -1 ], and NDBA-FP [（22 ±13） ng·L -1 ] were the dominant N -nitrosamine FPs. The concentrations of N -nitrosamines in the middle reaches of the Qingjiang River were higher than those in the upper and lower reaches. Furthermore, the concentrations of N -nitrosamines in the sample sites of sewage discharge and tributaries were significantly higher than those in other sampling sites. The monitoring results at the direct sewage discharge points indicated that the main source of N -nitrosamines in river water was the sewage carrying N -nitrosamines and their precursors. In addition, the concentrations of the three dominant N -nitrosamines including NDMA, NDBA, and NDEA were positively correlated with each other, mainly because of their similar sewage sources. The average carcinogenic risk to residents due to N -nitrosamine in drinking water sources was 2.4×10 -5 , indicating a potential carcinogenic risk. Moreover, due to the high concentrations of N -nitrosamine formation potentials in the Qingjiang River, the carcinogenic risk of drinking water may be even higher. The ecological risk assessment showed that the ecological risk quotient values of N -nitrosamines in the Qingjiang River watershed were lower than 0.002, which was negligible.

Hourly monitoring datasets of PM 2.5 mass concentration and associated chemical compositions were used to investigate the variations in their mass concentrations before, during, and after the 7th Military World Games held in Wuhan. Furthermore, the source analysis was conducted through PMF combined with the backward trajectory and concentration weighted trajectory cluster analysis. The study revealed the variations in PM 2.5 compositions and sources around the Wuhan Military Games period and their response to local and surrounding regional control measures. This can provide a reference for regional precise prevention and control of PM 2.5 . Under the influence of emission reduction measures, PM 2.5 mass concentration during the control period [(31.3±12.0) μg·m -3 ] decreased by 14.7% compared with that before the control period, whereas the secondary components were obviously formed, in which sulfate, nitrate, and ammonium(SNA) increased by 25.6% in total. After the control period, owing to the decrease in humidity and the influence of the northwest air mass, the mass concentration of SNA decreased by 36.9%, whereas the mass concentration of mineral elements increased by 4.7 times. The source apportionment results indicated that there was no significant difference between the vehicle emissions before and after the control( P <0.05). Compared with that in the non-control period, the contributions of industrial emission and coal burning decreased by 68.1% and 43.7%, respectively, whereas the contribution of secondary inorganic aerosol increased by 89.5%. With the lack of large-scale control of vehicle emissions, the mass concentrations of NO 3 - and NO x increased by 6.13 μg·m -3 and 3.56 μg·m -3 , respectively. The vehicle emissions peaked at 21:00 [(10.9±3.67) μg·m -3 ], reflecting the emissions of cargo vehicles, which were only allowed to pass at night during the control period. With the banning of ship navigation, the ship emission in the middle and lower reaches of the Yangtze River significantly decreased(48.8%). There were also high values of fugitive dust and industrial emissions near the Anhui section of the Yangtze River waterway, which reflected the dense distribution of industrial activities and road transportation along the Yangtze River. After the control period, the fugitive dust increased by 6.6 times, and the source areas were mainly distributed in Xiangyang and Jingmen.

Karst wetland plays an important role in the ecological environment; however, due to the existence of karst pipeline, pollutants can threaten the underground environment through the highly developed karst pipeline. Therefore, understanding the pollution characteristics of the karst surface environment is the premise of pollution ecological risk assessment and prevention. In this study, 24 organochlorine pesticides (OCPs) were analyzed to study the concentration, composition, source, and risk of OCPs in water and surface sediments in the Huixian Wetland of Guilin. The results showed that:the concentration of OCPs in water ranged from 3.17 ng·L -1 to 92.50 ng·L -1 , and the concentration of OCPs in sediment ranged from 1.16 ng·g -1 to 219.52 ng·g -1 , showing the main pollution characteristics of HCHs and DDTs. The concentration of OCPs in water was higher in the wet season than that in the dry season. The concentration of OCPs in sediments was higher in the dry season than that in the wet season. The isomer ratios revealed that OCPs in the study area were mainly derived from long-term degradation residues, and some sites had new input of lindane. Based on Monte Carlo simulation, the human health risk assessment of the study area showed that the 95% quantile carcinogenic risk of OCPs in water was greater than 1×10 -6 , with potential but acceptable health risk. The non-carcinogenic risk was lower than 1, which indicated that the level of OCPs residues in the water in the study area was not enough to cause non-carcinogenic risk to the human body.

The hourly concentrations of 102 volatile organic compounds (VOCs) in Wuhan from June to July in 2019 were obtained using an online monitoring instrument. The ρ (VOCs) varied from 24.9 to 254 μg·m -3 , with a mean value of (67.7±32.2) μg·m -3 . According to the air quality standard of ozone, the observation period was divided into clean and polluted episodes of O 3 . The differences in meteorological parameters, VOC concentrations, compositions, sources, and ozone formation potential (OFP) between clean and polluted episodes were analyzed and compared. The average mass concentrations of NO x , CO, and VOCs in polluted periods exceeded those of clean periods by 34.9%, 25.0%, and 27.8%, respectively. The mass concentrations of alkanes, alkenes, aromatic hydrocarbons, and oxygenated volatile organic compounds in polluted periods were higher than those in clean periods by 40.7%, 39.5%, 26.9%, and 21.5%, respectively. The average OFP in polluted periods[(102±69.6) μg·m -3 ] exceeded that of clean periods by 33.5%. The average contribution rates of LPG combustion, industrial sources, vehicle emissions, natural sources, and solvent usage to VOCs were 3.4%, 2.5%, 0.2%, 1.3%, and 1.4% lower than those of the clean periods, respectively, whereas the gasoline evaporation increased by 8.8% in polluted periods. The contributions of vehicle emissions and gasoline evaporation exhibited higher values in the morning and evening, with lower values in the afternoon, which may have been related to peak vehicles emissions. The contribution of LPG combustion peaked along with the cooking time. The concentration weighted trajectory showed that the main sources of VOCs in polluted periods were from local emissions and surrounding regions in the northeastern direction of Wuhan. In polluted periods, gasoline evaporation and LPG combustion should be emphasized for preventing O 3 pollution in the summer in Wuhan.

In order to investigate the pollution characteristics and sources of water-soluble ions in atmospheric PM 2.5 in different regions of central China during summer, Wuhan, Suizhou, and Pingdingshan were selected as urban, suburban, and rural monitoring stations, respectively, to collect PM 2.5 samples, and the mass concentration of PM 2.5 in the atmosphere and the contents of eight water-soluble ions were analyzed. The results showed that ρ (water-soluble ions) at the three sites showed obvious spatial distribution characteristics, with Pingdingshan[(36.29±9.82) μg·m -3 ] > Wuhan[(32.55±10.05) μg·m -3 ] > Suizhou[(26.10±6.23) μg·m -3 ], accounting for 52.47%, 51.32%, and 48.61% of the PM 2.5 mass concentration, respectively. In the Pingdingshan station, the proportion of water-soluble ions was the largest due to biomass combustion in the rural area. Additionally, SNA (SO 4 2- , NO 3 - , and NH 4 + ) were the main ionic components, accounting for 95.65%, 96.12%, and 97.33% of the total water-soluble ions, respectively. The mean values of SOR of the Wuhan (0.64) and Suizhou (0.63) stations were higher than that of the Pingdingshan station (0.50), whereas the NOR values of the Wuhan (0.18) and Pingdingshan (0.19) stations were higher than that of the Suizhou station (0.15). The difference in SOR and NOR among stations was affected by the secondary conversion mechanism, the ammonia-rich environment, and the surrounding traffic sources, respectively. The PM 2.5 at the Wuhan and Pingdingshan stations was in general alkaline, whereas at the Suizhou station it was neutral or weakly acidic, which was mainly caused by differences in NH 4 + . NH 4 + mainly existed in the form of (NH 4 ) 2 SO 4 and NH 4 NO 3 at the Wuhan and Pingdingshan stations, whereas at the Suizhou station it mainly existed in the form of (NH 4 ) 2 SO 4 or (NH 4 )HSO 4 . PCA-MLR analysis revealed that the Wuhan (89.27%) and Suizhou (67.38%) stations were the most affected by secondary conversion sources, whereas the Wuhan station was also affected by industrial sources (8.54%) and coal sources (2.27%). The pollution sources of the Suizhou station also included biomass combustion (24.42%) and dust sources (8.25%). The Pingdingshan station was most affected by biomass combustion (58.37%), followed by dust and combustion sources (38.05%) and traffic sources (3.58%). The analysis of potential sources of SNA (PSCF) showed that the main potential source areas of Wuhan were the boundary of Hubei, Henan, and Anhui and the southwest area of Anhui. Suizhou and Pingdingshan were affected by long-distance transport, and the main potential source regions were distributed in Shanghai, Jiangsu, and Anhui provinces from the east coast to the west.

In order to understand the pollution characteristics, spatial distribution, potential sources, and ecological risk of heavy metals in the sediments of Tangxun Lake, the contents of heavy metals (As, Hg, Cd, Cr, Cu, Pb, Zn, and Ni) in the surface sediments of Tangxun Lake were analyzed, and the pollution status and potential ecological risk degree of heavy metals in the sediments were evaluated using the geo-accumulation index and potential ecological risk index. The potential sources of heavy metal pollutants were analyzed by correlation and principal component analysis. The results showed that except for Cr, the contents of other heavy metals were higher than their background values. The contents of Hg, Cd, Zn, and Cu were higher in the southwest and northeast corners of the lake, which may come from the combined pollution of sewage discharge, fisheries, and surrounding industrial and agricultural activities. The geo-accumulation index and potential ecological risk showed that Hg and Cd were in moderate pollution; Cu, Pb, and Zn were in non-light pollution; and As, Cr, and Ni were in non-pollution. Except for Hg and Cd, there were serious and serious potential ecological risks, and the other elements were at a low risk level. The heavy metals in the surface sediments of Tangxun Lake showed a high ecological risk level.

China has always suffered from serious atmospheric fine particle (PM 2.5 ) pollution in winter, and PM 2.5 in Wuhan is particularly affected by regional transportation. Based on the hourly monitoring dataset of chemical components during the winter period, this study identified the real-time sources of PM 2.5 in Wuhan using a positive matrix factorization (PMF) model. A cluster analysis of backward trajectories and the concentration weighted trajectory were applied to obtain the potential source regions and transportation routes. During the observation period, ρ (PM 2.5 ) was (75.1±29.2) μg·m -3 , and there were two pollution episodes, one of which was mainly affected by the air masses coming from the northwest direction. In the first pollution episode, the increasing concentration of water-soluble ions was the main reason for the high PM 2.5 value, and the concentrations of NH 4 + , NO 3 - , and SO 4 2- were 1.6, 1.7, and 2.1 times those during the cleaning period, respectively. The other episode was affected by the air masses coming from the east direction, and the secondary organic components were clearly formed. Secondary inorganic aerosol contributed the most (34.1%) to PM 2.5 , followed by vehicular exhaust (23.7%), coal combustion (11.5%), road dust (10.9%), iron- and steel-producing processes (8.7%), and firework displays (5.7%). Biomass burning contributed the least (5.3%). Our examination of the diurnal variation revealed that the maximum contribution of iron- and steel-producing processes appeared at 08:00[(17.5±18.8) μg·m -3 ], and the lowest was at 01:00[(10.4±10.9) μg·m -3 ], which stayed high in the daytime and low at night. The contribution of vehicular exhaust showed a double peak at 09:00[(42.1±24.8) μg·m -3 ] and 20:00[(41.6±19.5) μg·m -3 ]. In the first pollution period, the contribution rate of secondary inorganic aerosol increased significantly, indicating that the long-distance transport under the northwest air mass promoted the generation of secondary components. In the second pollution period, the contribution rates of vehicular exhaust, coal combustion, iron- and steel-producing processes, and road dust increased, mainly located in the local area, the northwest of Jiangxi and the south of Anhui province. This reflected the influence of industrial processes, road transportation, and dust contribution along the Yangtze River on PM 2.5 . Biomass burning had a relatively high contribution for air masses from the northern regions, including Henan, Anhui, the south of Hebei, and the southwest of Shanxi provinces. The regional transport of pollutants from biomass combustion in the North China Plain during the winter would have an impact on Wuhan. This study can provide scientific and technological support for identifying the causes of atmospheric haze pollution in Wuhan during the winter and for the joint prevention and control of atmospheric particulate matter.

In recent years, frequent haze episodes have resulted in the deterioration of air quality of the Fenwei Plain during winter and holidays. Besides coal combustion and industrial emissions, the topography and climate of the Fenwei Plain were also the main causes of the haze. The samples were collected in Linfen of Fenwei Plain during the Spring Festival from February 2 to February 13, 2019. The 13 elements(Li, Be, Ti, Rb, Sc, Y, La, Ce, Zr, V, Tl, U, and Sn) in PM 2.5 were determined by inductively coupled plasma mass spectrometry(ICP-MS). Combined with the meteorological data, the spatial and temporal distribution of pollutants and potential source analysis were evaluated by cluster analysis and backward trajectory. The average concentration of SO 2 was 58.39 μg·m -3 during the sampling period, which exceeded the 24 h average mass concentration limit(50.00 μg·m -3 ) of national ambient air quality standard(GB 3095-2012). The average concentrations of O 3 , NO 2 , and CO was 52.15 μg·m -3 , 29.02 μg·m -3 , and 2.29 mg·m -3 , respectively. The results showed that SO 2 was the dominated pollutant. NO 2 and CO were mainly affected by diffusion from urban areas. The backward trajectory analysis indicated that the basin topography of the Fenwei Plain may be the main cause of the haze. The analysis of potential source contribution function(PSCF) of soil sources showed that the potential dominated areas included Northern Shaanxi, southern Gansu and Southern Ningxia., which were mainly affected by the monsoon climate.

To explore the pollution characteristics and potential health risks of heavy metals in PM 2.5 on haze days in Central China, PM 2.5 samples were collected from the Huanggang monitoring station, a regional observation point in Central China, between January 13 and 24, 2018. The contents of Cr, Mn, Co, Ni, Cu, Zn, As, Cd, Sn, and Pb in PM 2.5 were analyzed by inductively coupled plasma mass spectrometry(ICP-MS), and the enrichment factor method was used to determine the potential risk based on the exposure model recommended by the Environmental Protection Administration(EPA). The results showed that during the observation period, the concentrations of Zn in PM 2.5 were highest, and the concentrations of the carcinogens As and Cd were higher than the secondary standard limits of China's ambient air quality standard(GB 3095-2012), with 70% of these elemental concentrations accounting for the largest proportion in the middle haze period. The enrichment factor analysis showed that Cd, Sn, Co, Pb, and Zn were the most abundant elements, especially during the middle haze period, and were mostly derived from transportation and coal combustion. The results of the human health risk assessment showed that exposure via hand-mouth feeding was the main non-carcinogenic risk, and the exposure and non-carcinogenic risks of children were significantly higher than those of adults. Pb poses a non-carcinogenic risk to children, while heavy metals in PM 2.5 pose no non-carcinogenic risks to adults and carcinogenic heavy metals pose no carcinogenic risks.

This study provides data and theoretical support for the prevention and control of air pollution in central China. From January 13, 2018, to January 25, 2018, 48 PM 2.5 samples were collected in Huanggang by particulate matter samplers during a severe pollution episode. Twelve elements (Li, Be, V, Se, Sr, Mo, Ag, Ba, Tl, Th, Bi, and U) were analyzed by ICP-MS. A positive definite matrix factor (PMF), trajectory model of the cluster analysis, potential source analysis (PSCF), and the concentration weight analysis method (CWT) were applied to analyze the potential pollution sources and determine the transmission channel. The results showed that the internal cause of the pollution was the appearance of static, stable, and high humidity meteorological conditions, while the external cause was the input of pollution. Five types of pollution source were determined:fuel combustion (10.59%), crustal (24.22%), industry (3.16%), coal (47.57%), and traffic (14.45%). Two main types of air flow path were found; short distance transmission accounted for 62.50% whereas long distance transport accounted for 37.50%. The major contributors to the pollution included central and eastern Hubei, northeastern Hunan, southwestern Anhui, and southern Henan. North-south transmission channels were observed for central China. In addition to local pollution, the impact of regional transmission should not be ignored. In the emergency response period for heavy pollution during the autumn and winter, all regions need to control emission reduction measures. Joint prevention and control are the keys to air pollution control.

Wood and economic crops are still widely used in rural areas of China. Although their combustion is an important source of volatile organic compounds (VOCs), study on their emission characteristics is relatively weak. In this study, three kinds of wood (poplar, cedarwood, and citrus branches) and six economic crop straws (soybean stalk, sesame stalk, corn cob, cotton stalk, peanut stalk, and corn stalk) were selected and their burning was simulated in the laboratory. A dilution tunnel system was used to dilute the smoke, and then Tedlar bags were used to collect the smoke. The compositions of 102 VOCs were analyzed by Agilent 7820A/5977E gas chromatography/mass spectrometry. The ozone formation potential (OFP) of VOCs for different types of biomass burning was analyzed. The results indicated that there are differences in the VOC compositions of different types of biomass burning emissions. Ethane (11.1%), trans-2-pentene (15.4%), ethylene (8.3%), and dichloromethane (11.9%) are the main VOCs emitted from poplar and cedarwood burning. Toluene (49.8%) is the most abundant species of VOC emitted from burning of citrus branches. Ethylene (11.8%-17.5%) and acetone (9.2%-14.7%) are the main VOCs components of straw burning. Corn stalks, peanut stalks, and citrus branches have similar VOC source profiles, with the coefficient of divergence less than 0.1. The benzene/toluene ratio for biomass burning emissions obtained in this study and in the literature is in the range of 0.030-6.48. It is arguable that a value higher than 1 indicated the impact of biomass burning. The contributions of alkenens, oxygenated VOCs, and aromatic hydrocarbons to the OFP of biomass burning were 30.6%-80.3%, 6.5%-21.0%, and 3.8%-56.5%, respectively. The components contributing more than 10.0% to the OFP are ethylene, propylene, trans-2-pentene, cis-2-pentene, toluene, and propionaldehyde.

This study investigates the elemental characteristics and sources of aerosol fine particulate matter (PM 2.5 ) samples obtained from Pingdingshan, Suizhou, and Wuhan, Central China, in June 2017. Thirteen kinds of elements (Ti, Zn, Cu, Cr, As, Pb, Fe, Ni, Se, V, Sb, Cd, and Co) were analyzed by inductively coupled plasma mass spectrometry (ICP-MS), and three source identification methods-enrichment factor, principle component analysis and multiple linear regression (PCA-MLR), and backward trajectory clustering-were applied. The results showed that Zn was the highest trace element in PM 2.5 in samples from Pingdingshan, Suizhou, and Wuhan, and that the concentration of As exceeded the annual limit of Chinese air quality standards (GB 3096-2012). Concentrations of Pb and Cd in PM 2.5 in samples from the three cities during the summer were low. The enrichment factor coefficients for Se, Sb, Cd, As, Cu, and Zn exceeded 10, which suggests that summer pollution from human activities was serious, for example, the enrichment factor coefficient for Se was>600. PCA-MLR and backward trajectory clustering analysis results showed that the main pollution sources in Pingdingshan during the summer were industrial fuel oil (57.90% of total), traffic pollution (24.40%), coal combustion (6.10%), and mine soil (11.60%). The main pollution source in Suizhou was fuel, which contributed 54.30% of the total. Wuhan was mainly affected by industrial emissions (60.80% of the total) and motor vehicle pollution (39.20%). Hence, Wuhan and Suizhou were mainly affected by local source emissions, whereas Pingdingshan was jointly affected by local emissions and regional inputs during the summer.

Seventeen soil samples were collected along the main stream of the Hanjiang River in April 2013. Thirteen types of organochlorine pesticides (OCPs) were detected in the samples by gas chromatography with a 63 Ni electron capture detector. The purpose of this study was to investigate the distribution, composition, and source of OCPs and assess the potential health risks for local residents. The 13 types of OCPs were all detected in this region, ranging from 2.97 ng·g -1 to 1275.79 ng·g -1 , and the detection rates were 75%-100%. The contribution trends of both hexachlorocyclohexanes (HCHs) and dichlorodiphenyltrichloroethanes (DDTs) were upstream < midstream < downstream. Based on the ratio method, the HCHs were mainly from technical HCH input. Furthermore, there was DDT input recently, which contained industrial DDT and dicofol. The DDTs concentrations significantly correlated with total organic carbon. The values of cancer and non-cancer risks (10 -12 -10 -8 and 10 -6 -10 -3 ) were both lower than the corresponding thresholds (10 -6 and 1), which indicated that the soils in the Hanjiang River Basin had no harmful effects on local residents.

Ten sampling points were distributed approximately equidistantly in the Dajiuhu lake wetland, and soils from the depths 0-10 cm, 10-20 cm, and 20-30 cm were collected in April 2012. Gas chromatography-mass spectrometry (GC-MS) was used to analyze the remote mountain wetland shallow soils, and 16 kinds of USEPA priority controlled polycyclic aromatic hydrocarbon (PAH) pollutants were identified. The ∑ 16 PAHs content ranges of the shallow soils of this region were 48.55-984.73 ng·g -1 , 14.36-806.47 ng·g -1 , and 12.84-1191.53 ng·g -1 in the 0-10 cm, 10-20 cm, and 20-30 cm layers, with a mean of 302.94 ng·g -1 , 142.98 ng·g -1 , and 208.68 ng·g -1 in the three layers, respectively. The concentrations of seven carcinogenic PAHs ranged from 21.20-844.29 ng·g -1 , 2.96-592.06 ng·g -1 and 0.66-964.70 ng·g -1 in the three soil layers, with means of 197.25 ng·g -1 , 93.16 ng·g -1 , and 147.16 ng·g -1 that accounted for 65.12%, 65.13%, and 69.08% of the total PAHs in the three soil layers, respectively. The concentrations of PAHs in the areas with peat were significantly higher than that in the soil. PAHs having 4-6 rings were the dominant ones. The ratios IcdP/(IcdP+BghiP) and Pyr/BaP showed that the PAHs in the shallow soil form the Dajiuhu lake wetland mainly came from burning fossil fuels and wood. In recent years, the entry of tourist vehicles has contributed significantly to the increase in PAHs. The regression analysis on peat surface layer single body PAH and total PAHs showed that Chr, BbF, IcdP, and BaA could be used as a signaling property of mountain wetland PAH pollution.

An online continuous monitoring system was used to determine the volatile organic carbons (VOCs) in the ambient air of a typical petrochemical industrial park in autumn (Sep., Oct., Nov.) of 2014. The composition, photochemical reactivity, temporal variation, and source of VOCs were analyzed. The results indicated that the mixing ratio of VOCs in autumnal ambient air of the study area was higher than those of other cities and industrial areas. Alkanes were the most abundant group in the VOC mixing ratio, and no significant temporal difference was observed among the three months studied. However, the alkanes, alkenes, and aromatics presented obvious diurnal variation, with single peak and trough values, while the acetylene exhibited "W"-shaped variation, with two minimum and one maximum values. Source apportionment using positive matrix factorization (PMF) indicated that the sources of VOCs in the study area of natural gas transportation and solvents, such as from leakage or volatile oil refinery processing, followed by other traffic sources and asphalt have some contribution. Alkenes and alkanes were the dominant groups of the source apportionment composition, as expressed by the propylene-equivalent (Propy-Equiv) and maximum incremental reactivity (MIR) methods, respectively.

Concentrations of volatile organic compounds (VOCs) in ambient air of a typical petrochemical industry park were measured using an on-line monitor (TH-300B) from December 2014 to February 2015. The composition, temporal variations, sources, and photochemical reactivity of VOCs were analyzed. Alkanes were the most abundant VOC species and contributed to 86.73% to total VOC concentrations in winter. Concentrations of TVOCs, alkanes, alkenes, and aromatic hydrocarbons were high at night and low during the day. The changes in alkane and alkene concentrations were consistent with those in TVOC concentrations. Using principal component analysis and multiple linear regression (PCA-MLR) in combination, five sources of VOCs were identified; fuel evaporation, industrial emissions, a mix of gasoline vehicle exhaust and plant emissions, diesel vehicle exhaust emissions, and fuel combustion with contributions of 60.02%, 8.50%, 2.07%, 12.21%, and 17.20%, respectively. Propylene-equivalent concentration (Propy-Equiv) and maximum incremental reactivity (MIR) method were used to calculate the contributions of VOCs measured in the study area to ozone production. Alkanes contributed most to ozone production followed by alkenes and aromatic hydrocarbons. The contribution rate of cyclopentane, n-butane, and 1-pentene were higher owing to their long photochemical age in the study area.

The concentration, potential source and health risks of 16 polycyclic aromatic hydrocarbons (PAHs) in the atmosphere of Dajiuhu, Shennongjia, China, were studied. Polyurethane foam (PUF) Passive air samplers (PAS) were settled. The results indicated that the total concentrations of 16 PAHs in different samples ranged from 6.94 to 184.23 ng·m -3 , with the mean of 30.36 ng·m -3 . The dominant compounds were low rings PAHs, such as Phe, Nap, Pyr, Fla, Flu and Ant. Compared with other regions, the PAHs pollution of Dajiuhu atmosphere was at a low level. Higher PAHs concentrations were detected in nearby Deer farm, Dajiuhu peat area and Dajiuhu Wetland Authority. Higher PAHs concentrations were detected in autumn and winter, whereas lower concentrations were detected in spring and summer. Potential pollution sources of PAHs were investigated by diagnostic ratios and backward trajectory analysis, which indicated that coal and biofuel combustion, vehicle emissions and petroleum were the main sources. PAHs of Dajiuhu in air not only came from local emission, but also originated from Hubei, Henan and Hunan's atmosphere transport for most part and long range transport from northwest direction for small part. Health risks assessment results showed that the annual average concentration of total Benzo(a)pyrene-equivalent carcinogenic potency (∑BaP eq ) was 0.208 ng·m -3 , lower than the value recommended by Ambient Air Quality Standard of China(GB 3095-2012, 1 ng·m -3 ), indicating a low carcinogenic risk for the local residents.

Mangrove wetland plays an important role in coastal environment. A total of 10 surface water samples and 7 surface sediments samples were collected in March, 2015 from Nansha mangrove wetland, and 8 compounds of organochlorine pesticides (OCPs) were determined by GC-ECD to investigate residues level, source, and ecological risk of these compounds in the study region. The result showed concentrations of OCPs in water ranged from 1.89 to 90.19 ng·L -1 (mean 30.16 ng·L -1 ), and concentrations of OCPs in sediments varied from 3.10 to 16.02 ng·g -1 (average 8.58 ng·g -1 ). Compared with other estuaries and harbors around the world, concentrations of OCPs in this study stayed at a median pollution level. The mean values of distribution coefficient of HCHs and DDTs between water and sediments were 857 and 368, respectively. Sediments in some parts of the area, whose distribution coefficient was relatively high, may bring water the secondary pollution. Source analysis indicated that HCHs mainly originated from the application of Lindane, and DDTs originated from mixed sources of dicofol and technical DDT. Compared with OCPs in water, OCPs in sediments might contain more historical residual components. OCPs in water had light ecological risk, but OCPs in sediments posed a potential high risk to mangrove ecosystem.

8 surface sediments and 8 water samples were collected from the Daye Lake in August 2015.The 16 kinds of EPA control polycyclic aromatic hydrocarbons (PAHs) were analyzed by GC-MS.The results showed that the PAHs concentrations of surface sediments and water ranged from 35.94 ng·g -1 to 2032.73 ng·g -1 and from 27.94 ng·L -1 to 242.95 ng·L -1 ,with average contents of 940.61 ng·g -1 and 107.77ng·L -1 ,respectively.The distribution of PAHs in surface sediments indicated that the contents in the center samples were higher than those in the bank samples,but the water showed nearly the opposite tendency.The 4-5 rings high molecular weight PAHs were the main components in the surface sediments,and the 2,4 and 5 rings PAHs were given priority in water.Compared with the other domestic and oversea lakes,the PAHs pollution of the Daye Lake was at a moderate level.Source apportionment showed that the PAHs in surface sediments and water from the Daye Lake came from the combustion source,HWM-PAHs were the dominant part of the PAHs in the sediment,reflecting the sediment PAHs pollution under the effects of mining and smelting over a long period;All monomer PAHs and total PAHs content in sediment did not exceed the ERM and FEL limiting values,showing that there was no particularly serious ecological risk caused by PAHs in the surface sediments from the Daye Lake;the incremental lifetime cancer risks assessment showed that the uptake risk of PAHs in Daye Lake water through the ingestion and dermal absorption were both in the acceptable range recommended by the USEPA,but all sites had higher risk than the acceptable risk level recommended by the Sweden environmental protection agency and Royal society.The pollution of seven carcinogenic PAHs needs prevention and control.