Effects and Mechanisms of Different Types of Biochar on Heavy Metal Passivation during Sludge Composting.

The effects and mechanisms of the different types of biochar on heavy metal passivation are still not fully understood. This study compared the effects of three types of biochar on heavy metal passivation during sludge composting. Compared with composting without biochar, rice husk biochar was most effective for the passivation of Zn and Pb, with increased passivation rates of 1.90% and 20.43%, respectively. In contrast, sludge biochar was the most effective for the passivation of Cr and Hg, with increased passivation rates of 28.30% and 3.09%, respectively. Coconut shell biochar showed the best performance for the passivation of Cu, Ni, As, and Cd, and was enriched with micropore structures, which possibly led to the adsorption and reaction of heavy metals, organic matter, and microorganisms. The improved passivation effect of the rice husk and sludge biochar on heavy metals can be attributed to the improved humification of organic matter. This study suggests that specific types of biochar should be considered for the passivation of different types of heavy metals for practical applications.

[Characteristics and Source Apportionment of Volatile Organic Compounds in Zhanjiang in Summer].

Ozone pollution is intensifying in China, and its related studies are weak in non-focus regions and non-focus cities. Here, we investigated the characteristics and sources of volatile organic compounds (VOCs) at three sampling sites in Zhanjiang. We analyzed 101 VOCs using a gas chromatography-mass spectrometry/hydrogen ion flame detector (GC-MS/FID) and high-performance liquid chromatography (HPLC) using a Summa canister and DNPH adsorption tube. We calculated the ozone formation potential (OFP) of VOCs and used the positive matrix factorization (PMF) model for source apportionment. The results showed that the mean φ(TVOCs) was 1.28×10-7, and the dominant contributors were OVOCs (52%), followed by alkanes (36%), alkenes (7%), halogenated hydrocarbons (2.42%), aromatic hydrocarbons (1.61%), and alkynes (0.78%). The diurnal variation in VOCs was influenced by photochemical reactions; the ratio of aromatic hydrocarbons and alkanes was high in the morning and evening and low at noon, whereas OVOCs had a low ratio in the morning and noon and high in the evening, influenced by primary emissions and the upwind transport of pollutants. The OFP was 3.28×10-7, and the dominant species were formaldehyde, butene, n-butane, butanone, and acetaldehyde.The analysis of X/E values (characterizing the aging degree of air masses) and backward trajectories of air masses showed that during the sampling, when influenced by air masses from the south or southwest, X/E was small, and the aging degree of air masses was high, indicating the influence of regional transport; when influenced by air masses from the east or southeast direction, X/E was large, and the air masses were fresh, and VOCs were mainly from local emissions. Six emission sources of VOCs, including industrial emissions, gasoline vehicle exhaust and gasoline evaporation, regional background and transport sources, biomass combustion, diesel vehicles and marine shipping emissions, and solvent use emission sources, were resolved using the PMF model, with contributions of 36.05%, 28.99%, 13.84%, 10.13%, 7.05%, and 3.95%, respectively.Zhanjiang should strengthen the supervision of formaldehyde, butene, n-butane and butanone, industry sources, and mobile sources as the focus of control.

Synergistic effect of hydrogen bonding and π-π interaction for enhanced adsorption of rhodamine B from water using corn straw biochar.

Dyes adsorption to biochar via hydrogen bonding, and π-π interaction alone have attracted much research attention, however, their synergism in adsorption mechanisms remains largely unnoticed. The synergistic effects of the hydrogen bonding and π-π interaction might improve the adsorption capacity and need more understanding to prepare high-capacity biochar. In this work, we evaluated the adsorption of various dyes on biochar prepared via the activation of potassium bicarbonate and urea (named BC-KN) to explore their synergistic effects. Batch experiments indicated the BC-KN showed a high adsorption capacity to rhodamine B at 4839.0 mg/g, azure B at 4477.7 mg/g, and methylene blue at 2223.0 mg/g, respectively. The mechanism of such significant adsorption was investigated by their comparative experiments, characterizations, and computational analyses. The computational analyses suggested that the synergism of the hydrogen bonding and π-π interaction improves the adsorption energies of BC-KN/RhB system from -10.35 kcal/mol to -20.49 kcal/mol. It can be concluded that the hydrogen bonding and π-π interaction can synergize to significantly improve the adsorption by increasing the π-electron density and shortening the distance of aromatic rings, thus dyes with H-donor show significantly better adsorption capacities. The insight of hydrogen bonding being the governing factor in the synergistic system will help produce high-capacity biochar in removing aromatic dyes and suggest a sustainable technology for the efficient decolorization of dye effluent to minimize its damage to the health and environment.

[Chemical Characteristics and Sources of Atmospheric Carbonyls During the 2014 Beijing APEC].

Pollution characteristic and variation trend of atmospheric carbonyls were investigated in November during the 2014 Beijing APEC. Formaldehyde, acetaldehyde and acetone were the dominant carbonyls, accounting for 82.66% of total carbonyls, and especially, formaldehyde accounted for 40.12% of total carbonyls. Atmospheric concentrations of total carbonyls decreased by around 64.10% after the clean air policy was carried out during the Beijing APEC, and the variation trend of carbonyls showed a similar pattern to those of other pollutants like PM2.5 during the APEC. Strong correlations (R² of 0.67-0.98) were observed among formaldehyde, acetaldehyde, acetone and total carbonyls during and after the APEC, indicating that they had similar sources; however, poor correlations (R² of -0.11-0.42 and 0.16-0.94, respectively) were observed before the APEC, implying different emission sources for ambient carbonyls. The calculated ratios of C1/C2, C2/C3 and OC/EC indicated that both vehicles and coal emissions were responsible for atmospheric carbonyls before the APEC, and emissions from coal burning were the major contributor to atmospheric carbonyls during and after the APEC, especially after the APEC.

Photochemical production of atmospheric carbonyls in a rural area in southern China.

For the first time, ambient carbonyls were measured in a rural area in southern China from August 2012 to February 2013 to investigate their distribution characteristics and sources. Formaldehyde, acetaldehyde, and acetone were the three most abundant carbonyls, which accounted for 83-95 % of total seven carbonyls identified. The O3 formation potential of carbonyls in summer (59.55 µg/m(3)) was approximately ten times greater than that (6.37 µg/m(3)) in winter, and calculated photolysis rates were significantly faster in summer than those in winter, suggesting intensive photochemical activities in summer. Seasonal and diurnal variations of carbonyls showed that (1) the concentration of total carbonyls in summer (12.62 ± 10.83 µg/m(3)) was approximately five times greater than that in winter (2.33 ± 0.90 µg/m(3)), and a similar trend applied to the three abundant carbonyls; (2) the average summer to winter (S/W) ratio of formaldehyde and acetaldehyde was 10-13, and the S/W ratio of acetone was ~2.59; and (3) the highest concentrations of the three carbonyls and total carbonyls occurred at 14:00-16:00 with high temperature and intensive sunlight, especially in summer. These variations provided direct evidence for significant photochemical production of ambient carbonyls. Average C1/C2 ratios (3.07 ± 1.62) in summer were much greater than those (1.28 ± 0.25) in winter, and average C2/C3 ratios (35.09 ± 58.67) in summer were significantly greater than those (4.75 ± 2.12) in winter, both cases indirectly implying positive photochemical productions in summer. Especially, strong correlations (R(2) = 0.63-0.98) of temperature and sunlight intensity with the three abundant carbonyls and total carbonyls were observed, indicating a similar causal source such as significant photochemical production.

Distributions, possible sources and biological risk of DDTs, HCHs and chlordanes in sediments of Beibu Gulf and its tributary rivers, China.

Thirty-five surface sediment samples collected from Beibu Gulf and its tributary rivers, China were analyzed for DDTs, HCHs and chlordanes. Total concentrations of DDTs, HCHs and chlordanes in sediments ranged from 0.59 to 126 ng g(-)(1), ND to 2.65 ng g(-)(1) and 0.27 to 3.41 ng g(-)(1) based on dry weight (dw), respectively. Concentrations of DDTs were higher than those reported in the sediments from other regions of the world, while concentrations of HCHs and chlordanes were relatively low. High concentrations of DDTs were observed in the harbor region and aquaculture bases and high concentrations of HCHs were found in the Qin River Estuary. The ratios of (DDE+DDD)/DDTs reflected a mixed input of weathered and fresh DDTs. The predominant ß-HCH indicated that HCHs in the study area mainly originated from the historical usage of technical HCH. The residues of DDTs would pose adverse biological effects on the study area.

Measuring δ(13)C values of atmospheric acetaldehyde via sodium bisulfite adsorption and cysteamine derivatisation.

δ(13)C values of gaseous acetaldehyde were measured by gas chromatograph-combustion-isotope ratio mass spectrometer (GC-C-IRMS) via sodium bisulfite (NaHSO(3)) adsorption and cysteamine derivatisation. Gaseous acetaldehyde was collected via NaHSO(3)-coated Sep-Pak(®) silica gel cartridge, then derivatised with cysteamine, and then the δ(13)C value of the acetaldehyde-cysteamine derivative was measured by GC-C-IRMS. Using two acetaldehydes with different δ(13)C values, derivatisation experiments were carried out to cover concentrations between 0.009×10(-3) and 1.96×10(-3) mg·l(-1)) of atmospheric acetaldehyde, and then δ(13)C fractionation was evaluated in the derivatisation of acetaldehyde based on stoichiometric mass balance after measuring the δ(13)C values of acetaldehyde, cysteamine and the acetaldehyde-cysteamine derivative. δ(13)C measurements in the derivertisation process showed good reproducibility (<0.5 ‰) for gaseous acetaldehyde. The differences between predicted and measured δ(13)C values were 0.04-0.31 ‰ for acetaldehyde-cysteamine derivative, indicating that the derivatisation introduces no isotope fractionation for gaseous acetaldehyde, and obtained δ(13)C values of acetaldehyde in ambient air at the two sites were distinct (-34.00 ‰ at an urban site versus-31.00 ‰ at a forest site), implying potential application of the method to study atmospheric acetaldehyde.

Nonmethane Hydrocarbons in Ambient Air of Hazy and Normal Days in Foshan, South China.

A first study of nonmethane hydrocarbons (NMHCs) on hazy and normal days was performed in Foshan for providing deep insight into the local deteriorating air quality. Ethane, propane, i-pentane, ethene, propene, ethyne, benzene, and toluene were eight most abundant compounds, accounting for 71%-85% of total NMHCs. Most hydrocarbons showed much higher levels on hazy days than normal days together with hydrocarbon/ethyne ratios and diurnal variations, indicating hazy days are more dominated by vehicular emission. Correlation coefficients (R(2)) of ethane, propane, ethane, propene, benzene, and total NMHCs with ethyne were 0.62-0.83, indicating these compounds are mainly related to vehicular emission. R(2) analysis indicated that solvent usage is responsible for toluene and other aromatic hydrocarbons (e.g., ethylbezene). Benzene/toluene (B/T) ratio was 0.44±0.23 during whole sampling periods, again indicating vehicular emission is the dominant source. Lower B/T ratio (0.30±0.14) on hazy days than that (0.58±0.21) on normal days suggested that solvent usage emitted toluene.

Characteristics of atmospheric non-methane hydrocarbons during haze episode in Beijing, China.

This study firstly focused on non-methane hydrocarbons (NMHCs) during three successive days with haze episode (16-18 August 2006) in Beijing. Concentrations of alkanes, alkenes, aromatic hydrocarbons, and ethyne all peaked at traffic rush hour, implying vehicular emission; and alkanes also peaked at non-traffic rush hour in the daytime, implying additional source. Especially, alkanes and aromatics clearly showed higher levels in the nighttime than that in the daytime, implying their active photochemical reactions in the daytime. Correlation coefficients (R (2)) showed that propane, n-butane, i-butane, ethene, propene, and benzene correlated with ethyne (R (2) = 0.61-0.66), suggesting that their main source is vehicular emission; 2-methylpentane and n-hexane correlated with i-pentane (R (2) = 0.61-0.64), suggesting that gasoline evaporation is their main source; and ethylbezene, m-/p-xylene, and o-xylene correlated with toluene (R (2) = 0.60-0.79), suggesting that their main source is similar to that of toluene (e.g., solvent usage). The R (2) of ethyne, i-pentane, and toluene with total NMHCs were 0.58, 0.76, and 0.60, respectively, indicating that ambient hydrocarbons are associated with vehicular emission, gasoline evaporation, and solvent usage. The sources of other hydrocarbons (e.g., ethane) might be natural gas leakage, biogenic emission, or long-range transport of air pollutants. Measured higher mean B/T ratio (0.78 ± 0.27) was caused by the more intensive photochemical activity of toluene than benzene, still indicating the dominant emission from vehicles.

The concentration and distribution of organochlorine pesticides in the air from the karst cave, South China.

Organochlorine pesticides (OCPs) in the air of Dayan Cave in Guilin were analyzed, to investigate the source and contamination levels. Generally, air outside of the cave had much higher concentrations than inside air, and both outside and inside air showed much lower contamination levels than those observed in other regions in China and abroad. The ratios of α-/γ-HCHs and the percentages of ß-(or δ-)HCH implied a residue of historical local technical HCH contamination. The DDT concentrations, o,p'-DDT/p,p'-DDT, and p,p'-DDE/p,p'-DDT suggested fresh DDT-containing products acted as the primary source of DDT for the air in Dayan Cave. An intermediate level concentration of α-endosulfan (156.00 pg/m(3)) was observed in the outside air, implying local source was dominant. Based on the similar sources of HCH and DDT and the relationships between outside and inside air, it appeared that outside air pollutants affected on inside HCH and DDT's distribution. For other OCPs, outside air might be major contributor to inside air contamination under conditions of high concentrations in outside air compared with low levels in inside air for semi-closed karstic caves.

Distribution and accumulation of metals in soils and plant from a lead-zinc mineland in Guangxi, South China.

Six kinds of metals were measured in soils and plant from the Siding Pb-Zn mineland, South China, to investigate the pollution and restoration technique. The mean Pb, Zn, Fe, Mn, Cu and Cr contents in soils were 5,215 ± 642, 13,352 ± 1,242, 24,755 ± 2,475, 438 ± 52, 67 ± 38 and 68 ± 31 mg kg(-1), respectively. The results revealed the mean contents of Pb and Zn exceeded the third level of China standard of soil (GB15618-1995) for 10.4 and 26.7 times, respectively. The soil of Siding Pb-Zn mineland has heavily been subjected to Pb and Zn pollution. 22 plant species from 13 families were found colonizing. There were great variations of metal contents in plant species with Pb 1.58-1496 mg kg(-1), Zn 7.56-204,256 mg kg(-1), Cu not detected (ND)-286 mg kg(-1), Fe 83-25,972 mg kg(-1), Mn 1.02-160 mg kg(-1) and Cr ND-152 mg kg(-1). Of the six metals, Fe content was the highest, followed by Pb and Zn, which were similar to the situation of the soil. The local pioneer species, Pteris vittata, was observed a higher accumulation and translocation capability for Pb, which could be chosen as pioneer of phytoremediations to restore Pb/Zn mineland.

Characteristics of atmospheric non-methane hydrocarbons in Foshan City, China.

Foshan is the most air-polluted city in Pearl River Delta. Non-methane hydrocarbons (NMHCs) were investigated for the first time in Foshan in winter 2008. Ethene, ethane, ethyne, propane, i-pentane, and toluene were the most abundant hydrocarbons and observed to be higher in Foshan than those in many other cities in China. Different from other cities, ethene and ethane were observed to be the two highest compounds in Foshan. Generally, the most abundant hydrocarbons showed high mixing ratios in the morning (0930-1030 hours), decreased to the lowest level in the afternoon (1430-1530 hours), and increased to higher value in the evening (1930-2030 hours). But i-pentane exhibited a different diurnal pattern with the highest level (13.4 ± 5.8 ppbv) in the afternoon, implying the acceleration of solvent evaporation resulting from higher temperature. Correlation coefficients (R(2) = 66% for n = 6 at 95% confidence level) of the individual hydrocarbons with ethyne and i-pentane indicated vehicular emissions were the main sources of ethene, propene, i-butene, isoprene, benzene and toluene, while gasoline evaporation was responsible for n-pentane, n-hexane, and n-heptane. The good correlation of most of the hydrocarbons with ethyne, indicating vehicular emissions, were the main sources of NMHCs. B/T ratio was 0.36 ± 0.06, implying vehicular emissions acted as the major contributors as well as additional emissions of toluene emitted from solvent usage. According to investigation, it also suggested that LPG leakage was the main source of propane, while NG leakage was responsible for ethane in Foshan City.

Organochlorine pesticides in the soil of a karst cave in Guilin, China.

Organochlorine pesticides (OCPs) including HCH, DDT, chlordane, endosulfan, and endosulfan sulfate were analyzed in surface soil of the Dayan Cave to investigate their source and concentration levels in September 2006. Generally, the data showed that outside soil of the cave had much higher concentrations than inside soil for the most detected OCPs in the cave and both inside soil and outside soil showed much lower concentration levels (basically, the levels of OCPs were less than 0.7 ng/g) than those observed in other regions within and outside China other than TC (ranging from 3.22 to 5.00 ng/g) and CC (ranging from 3.89 to 5.08 ng/g) in the soil outside. The ratios of α-/γ-HCH ranged from 0.88 to 1.20 in the soil of the cave, together with the averaged percentages of ß-HCH and δ-HCH among the total HCH isomers (accounting for 39.0% and 14.2%, respectively), implied that a historical residue of local technical HCH contamination was likely to be dominant in the soil of the cave. Based on (1) the accordance of TC/CC ratios (ranging from 0.83 to 0.98) between the values observed in the outside soil and the potentially available chlordane products in the markets, and (2) the high concentrations of TC and CC observed in the outside soil, it appeared that the illegal usage of technical chlordane was done in Guilin. The low concentrations of TC (0.02 to 0.56 ng/g) and CC (0.10 to 1.71 ng/g) in the inside soil, together with the significant distinctions of TC/CC ratios between the inside soil (ranging from 0.03 to 0.33) and the outside soil, implied that the chlordane in the inside soil of the cave was a historical residue of local technical chlordane contamination. The similar ratios of DDT isomers (o, p (')-DDT/p, p (')-DDT and p, p (')-DDE+DDD/DDT) between the outside soil and the inside soil of the cave suggested that they may have the similar DDT source. The ratios of p, p (')-DDE+DDD/DDT (ranging from 3 to 8) indicated that DDT was relatively aged. The values of o, p (')-DDT/p, p (')-DDT ratios (ranging from 3 to 7.5 with a mean value of 5.45) were found to be much higher than that of technical DDT, and very similar to that of dicofol products, implied that the primary source of DDT in the soil of the cave was most probably from dicofol-type DDT products. The low concentration levels of endosulfan and the higher levels of metabolite endosulfan sulfate indicated that the residue from historical usage of technical endosulfan was likely to be dominant in the soil of the cave.

Seasonal and diurnal variations of carbonyl compounds in the urban atmosphere of Guangzhou, China.

Seasonal and diurnal variations of carbonyl compounds were investigated at two sampling sites (Liwan and Wushan) in the ambient air of Guangzhou, China. Air samples were collected during 2005 from January to November, and carbonyl compounds were analyzed with HPLC. The results show that carbonyls exhibit distinct seasonal variation. The total concentrations of 21 carbonyls detected ranged from 2.64 to 103.6 microg m(-3) at Liwan and from 5.46 to 89.9 microg m(-3) at Wushan, respectively. The average total concentrations of carbonyls at both Liwan and Wushan decreased in order of summer>spring>autumn>winter. Formaldehyde, acetaldehyde, and acetone were the most abundant carbonyl compounds, which accounted for more than 60% of the total concentrations of carbonyls. The mean concentration ratios of summer/winter were all > 1.0 for the total concentrations and the individual carbonyl compound. The diurnal variation of carbonyls was not distinct in this study. The average concentration ratios of formaldehyde/acetaldehyde (C1/C2) varied from 0.71 to 1.32 and 0.65 to 1.14 at Liwan and Wushan, respectively, and the average concentration ratios of acetaldehyde/propionaldehyde (C2/C3) varied from 5.42 to 7.70 and 5.02 to 13.9 in Liwan and Wushan, respectively. Regarding photochemical reactivity of carbonyls and the ozone production, acetaldehyde, butyraldehyde, formaldehyde, and valeraldehyde account for 75-90% to the total propene-equivalent concentrations, while formaldehyde, acetaldehyde, valeraldehyde, butyraldehyde, and propionaldehyde contribute 89-96% to the total ozone formation potentials (ranging from 105 to 274 microg m(-3)). The ozone formation potentials in summer were higher by 1-2 times than those in the other seasons.

Carbonyl compounds and BTEX in the special rooms of hospital in Guangzhou, China.

The occurrence of carbonyl compounds and benzene, toluene, ethylbenzene and xylenes (BTEXs) was assessed in the indoor and outdoor air of a hospital in Guangzhou, China. The pharmacy room, the preparing traditional Chinese medicine room, the supply room (where the medical appliances are disinfected), the laundry and the garbage room were selected as sampling sites. Acetaldehyde (ranging from 4.56 to 66.8 microg m(-3)) was in all samples the most abundant among the 18 carbonyls detected, and toluene (ranging from 33.5 to 264 microg m(-3)) among the BTEXs. The indoor/outdoor (I/O) concentration ratios of BTEXs in the morning were always >1.0, and close to 1.0 or slightly <1.0 in the afternoon, while the concentration ratios of carbonyls in the afternoon showed large variation. These ratios demonstrate the significance of outdoor emissions that deteriorate the indoor air quality at the various rooms of the hospital. The possible sources of BTEXs and carbonyls in these rooms are discussed with the use of specific ratios and with the use of statistical methods, like principal components analysis.

Improvement of 2,4-dinitrophenylhydrazine derivatization method for carbon isotope analysis of atmospheric acetone.

Through simulation experiments of atmospheric sampling, a method via 2,4-dinitrophenylhydrazine (DNPH) derivatization was developed to measure the carbon isotopic composition of atmospheric acetone. Using acetone and a DNPH reagent of known carbon isotopic compositions, the simulation experiments were performed to show that no carbon isotope fractionation occurred during the processes: the differences between the predicted and measured data of acetone-DNPH derivatives were all less than 0.5 per thousand. The results permitted the calculation of the carbon isotopic compositions of atmospheric acetone using a mass balance equation. In this method, the atmospheric acetone was collected by a DNPH-coated silica cartridge, washed out as acetone-DNPH derivatives, and then analyzed by gas chromatography/combustion/isotope ratio mass spectrometry (GC/C/IRMS). Using this method, the first available delta13C data of atmospheric acetone are presented.