[Heavy Metal Pollution Characteristics and Ecological and Health Risk Assessment of Atmospheric PM2.5 in a Living Area of Zhengzhou City].

To study the pollution characteristics of atmospheric heavy metal elements in a living area of Zhengzhou City, assess the potential ecological risks, and determine risks to resident health in this city, the Wuhan Tianhong TH-16A Airborne Particles Intelligent Sampler was used to collect atmospheric PM2.5 in Zhengzhou City. The mass concentrations of 17 metal elements were analyzed by ambient air determination of inorganic elements by ambient particle matter wavelength dispersive X-ray fluorescence spectrometry. The source of heavy metals was analyzed by the enrichment factor method and principal component analysis. The ecological risk index method and the US Environmental Protection Agency's health risk assessment method were used to evaluate the potential ecological risks and residents' health risks from Cr, Cd, Cu, Zn, Ni, Pb, As, and other elements. The results showed that metals with higher enrichment factor values were Cd, Sb, Pb, and As, and Cd had the highest enrichment factor value. The sources of metal elements in a living area of Zhengzhou City were mainly crust/burning coal, fuel, garbage burning, metallurgical dust, and vehicle emission. The single factor potential ecological hazard index values of Cd, Pb, Zn, As, Cu, Ni, and Cr were 70420.2, 255.3, 204.6, 71.5, 36.9, 24.0, and 5.1, respectively. Cd, As, and Cr in a living area of Zhengzhou City posed a cancer risk, and Cd was the most harmful. Mn had a non-carcinogenic risk.

[Emission Characteristics Analysis and Health Risk Assessment of Unorganized VOCs in the Carbon Industry, Zhengzhou].

The three typical carbon enterprises in Zhengzhou were selected as research targets, and the emission characteristics of volatile organic compounds (VOCs) and their ozone formation potential (OFP) in different functional areas were studied. The US Environmental Protection Agency (EPA) health risk assessment model was used to evaluate the health risks of VOCs emitted by the carbon industry. The results showed that the concentration of VOCs in the production areas of the three research enterprises was between 89.77-964.60 µg·m-3, and the management area was between 51.46-121.59 µg·m-3. Naphthalene and carbon disulfide were at the highest concentrations in the carbon plants. The ozone formation potential of VOCs in the production area was between 75.42-1416.73 µg·m-3, and in the management area was between 65.32-202.42 µg·m-3, mainly from the contribution of aromatic hydrocarbons and olefins. The carcinogenic health risk (Risk) of VOCs in the production area was 3.5×10-5-2.8×10-3, and in the management area was 2.0×10-5-9.4×10-5, which was higher than the maximum acceptable level recommended by the EPA (10-6). The non-carcinogenic health risk index (HI) of the VOCs in the production area was 3.2-1.4×102, and in the management area was 4.3×10-1-3.8, except for the management area of the first enterprise, which was greater than 1, which may expose the workers. These health factors cause cancer and non-carcinogenic hazards.

[Health Benefit Evaluation for PM10 and PM2.5 Pollution Control in Zhengzhou, China, 2014-2016].

Based on the annual average concentration values, the health effects and health benefits as well as 95% confidence intervals of PM10 and PM2.5 pollution control from 2014 to 2016 in Zhengzhou were evaluated by applying the Poisson regression relative risk model. Results showed that the health benefits of PM10 pollution control were 18.18 billion RMB (15.04, 21.12), 24.25 billion RMB (20.25, 27.94), and 20.62 billion RMB (17.33, 23.92), which accounted for 2.7%, 3.3%, and 2.5% of the GDP of Zhengzhou, respectively, in 2014-2016. The health benefits of PM2.5 pollution control were 17.88 billion RMB (14.37, 21.16), 21.65 billion RMB (17.46, 25.53), and 17.25 billion RMB (13.78, 20.55), which accounted for 2.6%, 3.0%, and 2.1% of the GDP of Zhengzhou, respectively, in 2014-2016. After the PM10 and PM2.5 pollution was controlled, the number of urban beneficiaries was higher than that of rural areas, and acute bronchitis beneficiaries were higher than the beneficiaries of other health end-points. For chronic bronchitis, adults benefited more than children, while the opposite occurred for asthma. In this study, chronic bronchitis had the highest health benefit, followed by asthma, and outpatient and inpatient setting had the lower health benefits.

[Characteristics and Source Analysis of Water-Soluble Ions in PM2.5 in Zhengzhou].

In order to explore the pollution characteristics of water-soluble ions in PM2.5 in Zhengzhou, high time resolution and continuous observation of water-soluble inorganic ions in PM2.5 was conducted from December 1, 2017, to November 30, 2018, in Zhengzhou. The results showed that during the observation period, the average concentration of total water-soluble ions in Zhengzhou was 42.7 µg·m-3. The order of mass concentration of each ion, from large to small, was as follows:NO3-(17.7 µg·m-3), SO42-(10.2 µg·m-3), NH4+(9.0 µg·m-3), Cl-(2.3 µg·m-3), K+(1.3 µg·m-3), Na+(1.3 µg·m-3), Ca2+(0.8 µg·m-3), and Mg2+(0.1 µg·m-3). The mass concentration of total water-soluble ions was the highest in winter, slightly higher in autumn than in spring, and lowest in summer. The diurnal variation in single peak distribution was observed across the whole year in spring, summer, and autumn, while there was no significant diurnal variation in winter. The mass concentration of secondary inorganic ions (SO42-, NO3-, and NH4+) accounted for 43.8% of PM2.5, mainly in the form of (NH4)2SO4 and NH4NO3. There was a large degree of secondary transformation throughout the observation period; relative humidity had a significant influence on the sulfur oxidation rate, and temperature had a significant influence on the nitrogen oxidation rate. During the observation period, there was a good correlation between secondary ions, and K+ showed a good correlation with Mg2+ and Cl-. The main source of the secondary ions was the secondary conversion of gaseous pollutants. Mg2+ and Ca2+ were derived from soil dust and construction dust. K+ was one of the main biomarkers of biomass combustion. Na+ was mainly derived from sea salt and soil dust, and Cl- was derived not only from sea salt but also biomass and fossil fuel combustion. The results of principal component analysis showed that the water-soluble ions in PM2.5 in Zhengzhou were mainly affected by secondary transformation, combustion sources, and dust emission from soil or building construction.

[Emission Characteristics and List of Inorganic Elements in Fine Particles of Typical Industrial Kilns in Zhengzhou City].

Samples of particulate matter from flue gas emissions of typical brick, cement, and firebrick industrial kilns in Zhengzhou City were collected by dilution channel systems. Cr, Mn, Fe, Co, Na, Mg, Al, Si, P, S, Cl, K, Ca, Ti, V, Ni, Cu, Zn, Ga, As, Se, Sr, Cd, Sb, Sn, Ba, and Pb were analyzed. The emission factors (EFs) and emissions of inorganic elements of PM2.5 from kilns flue gases of three industries in Zhengzhou City during 2016 were calculated. A grid list of 1 km×1 km was also established. The results show that the highest concentration of total inorganic elements was in the firebrick industry, corresponding to(609.97±490.97) µg·m-3. The concentration of inorganic elements in the three industries accounted for 34%-54%, 27%-42%, and 23%-53% of PM2.5. The inorganic elements emitted from industrial kilns in brick and cement industries were mainly crust elements, and the highest concentration elements were Cl and Al. The inorganic elements emitted by industrial furnaces in the firebrick industry were mainly heavy metals, and the highest concentration element was Pb. The coefficient of divergence (CD) of inorganic elements in brick and cement industry was 0.389, that is slightly different. The CD between cement and refractory industry was 0.732, which represents a significant difference between inorganic element emissions. In 2016, the emissions of Pb, S, Zn, Cl, K, As, Fe, Si, Cr, Al, Na, and Ca in PM2.5 from major industrial furnaces in Zhengzhou City were 919.0, 793.1, 124.7, 378.6, 82.6, 12.2, 60.4, 145.4, 7.4, 86.6, 15.8, and 111.4 kg·a-1, respectively. Heavy metal emission in the Xinmi area was the highest, representing a high health risk.

[Size Distribution Characteristics of Water-Soluble Inorganic Ions During Summer and Autumn in Zhengzhou].

To study the compositional characteristics of atmospheric particulates with different particle sizes in the central city of Zhengzhou, China, a Tisch graded impact sampler was used to sample atmospheric particulates in summer and autumn. The mass concentrations of water-soluble inorganic ions, including anions (Cl-, F-, NO3-, and SO42-) and cations (Na+, Ca2+, NH4+, K+, and Mg2+) were measured by ion chromatography, and the online ion chromatography-based analyzer MARGA monitored the real-time concentration of particulate nitrate. The results showed that the average concentration of water-soluble ions in Zhengzhou City was (70.9±52.1) µg·m-3 during the sampling period, and the order of water-soluble ion mass concentrations was NO3- > SO42- > NH4+ > Ca2+ > Na+ > Cl- > Mg2+ > K+ > F-; NO3-, SO42-, and NH4+ accounted for 79.9% of total water-soluble ions. The NO3- concentration was mainly concentrated in the 0.65-3.3 µm particle size segment, despite the SO42- concentration being concentrated in the ≤ 1.1 µm particle size segment in autumn or summer. Both NO3- and SO42- had a bimodal distribution in summer and autumn and were mainly distributed as fine particles. NH4+ showed seasonal variation with a bimodal distribution in summer and a unimodal distribution in autumn. Zhengzhou City had serious ozone pollution in summer, and O3 and NO3- showed the "staggered peak" phenomenon, indicating photochemical reactions in the atmosphere. In autumn, water-soluble inorganic ion concentration in particulate matter was high, and the ratio of[NO3-]/[SO42-] was higher than 0.5. The mobile source is an important source of particles. NOR and SOR peaks were on the 1.1-2.1 µm particle size segment in summer, whereas those in the 0.65-1.1 µm particle size segment occurred in autumn. The sulfur gas-to-grain conversion in summer was larger than that of nitrogen, contrary to the result in autumn.

Influence of pyrene combination state in soils on its treatment efficiency by Fenton oxidation.

Interactions of hydrophobic organic compounds (HOCs) with soil organic matter (SOM) determine their combination state in soils, and therefore strongly influence their mobility, bioavailability, and chemical reactivity. Contact time (aging) of an HOC in soil also strongly influences its combination state and environmental fate. We studied Fenton oxidation of pyrene in three different soils to reveal the influences of SOM, contact time, and combination state on the efficiency of vigorous chemical reactions. Pyrene degradation efficiency depended strongly on the dose of oxidant (H(2)O(2)) and catalyst (Fe(2+)); the greatest degradation was achieved at an oxidant to catalyst molar ratio of 10:1. Pyrene degradation differed among the three soils, ranging from 65.4% to 88.9%. Pyrene degradation efficiency decreased with increasing SOM content, and the aromatic carbon content in SOM was the key parameter. We hypothesize that pyrene molecules that combine with the compact net structure of aromatic SOM are less accessible to Fenton oxidation. Furthermore, pyrene degradation efficiency decreased considerably after aged for 30 days, but further aging to 60 and 180 days did not significantly change degradation efficiency. The Fenton oxidation efficiency of pyrene in both unaged and aged soils was greater than the corresponding desorption rate during the same period, perhaps because Fenton reaction can make pyrene more accessible to the oxidant through the enhancement of HOCs' desorption by generating reductant species or by destroying SOM through oxidation.

Influence of Fenton oxidation on soil organic matter and its sorption and desorption of pyrene.

The influences of Fenton oxidation on the content and composition of soil organic matter (SOM) and the consequent change of its sorption and desorption of pyrene were investigated using three soil samples. The results showed that both the content and the composition of the SOM changed, with total SOM content decreasing. The content of humic acid (HA) was reduced, while the content of humin did not change significantly, however the content of fulvic acid (FA) had a tendency to increase. Correlation analysis of soil-water distribution coefficient (K(d)) and different parts of the SOM reveals that humin and HA are the key factors controlling the sorption of pyrene. Organic carbon normalized K(d) (K(OC)) varied to different extents after Fenton oxidation due to the change of SOM composition. The reduction of K(OC) is significant in Soils 1 and 2 where large part of HA was reduced to FA, whose sorption ability is low. The change of K(OC) by oxidation in Soil 3 is not so significant due to that the percentage of humin and HA in Soil 3 did not change greatly after oxidation. Desorption was hysteretic in all cases, and humin percentage was found to be the key factor on the extent of desorption hystersis. Oxidation made desorption more hysteretic due to the elevated proportion of humin.