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Real-time analysis of volatile organic compounds (VOCs) in air is useful both for source identification and emissions compliance applications. In this work, two complementary triple quadrupole mass spectrometers, fitted with an atmospheric pressure chemical ionization (APCI) and a low pressure chemical ionization (LPCI) source, respectively, were deployed simultaneously to investigate emissions of VOCs associated with an Ontario-based chemical waste disposal facility. Mobile measurements performed upwind and downwind of the facility enabled selection of the best locations for stationary sampling. Seven separate field studies were undertaken between 2000 and 2016 to assess how emissions of VOCs have changed at the site as a function of time. Up to twenty-nine VOCs were successfully identified and quantified using MS/MS in each study. Simultaneous deployment of the two mass spectrometers enabled the detection of polar VOCs including alcohols, esters, amines and ketones as well as non-polar aromatic VOCs including benzene and naphthalene in real time. Concentrations of VOCs were found to decrease significantly in the vicinity of the facility over the sixteen year period, in particular since 2007. Concentration values for each year are compared with odour thresholds and provincial guidelines and implications of future expansion of on-site solid waste landfill volumes are also discussed.

Phragmites australis and Chloris virgata are native, dominant, salt-tolerant grass species that grow in the Yellow River Delta, China, and have potential applications in the phytoremediation of petroleum-polluted saline soil. The characteristics of endophytic bacterial communities of Phragmites australis and Chloris virgata and their functions in hydrocarbon degradation and plant growth promotion have been studied using both high-throughput sequencing and conventional microbial techniques. Through 16S rRNA gene amplicon sequencing, we found five bacterial phyla that were dominant among the endophytic bacterial communities of the two grass species, including Proteobacteria, Actinobacteria, Firmicutes, Bacteroidetes, and Tenericutes. The phylum Proteobacteria was common among the endophytic bacterial communities of the two grass species. The diversity in the endophytic bacterial community of Chloris virgata was generally higher than that in the community of Phragmites australis. Thirty-eight hydrocarbon-degrading endophytic bacteria were isolated from the two grasses via culturing techniques. Based on phylogenetic analyses, the bacterial isolates were classified into the phyla Proteobacteria, Firmicutes, and Actinobacteria. The majority of strains belonged to the genera Bacillus and Pseudomonas. More than 70% of the isolates of hydrocarbon-degrading endophytes exhibited the ability to stimulate plant growth. These isolates mainly belonged to Bacillus sp., Pseudomonas sp., Beijerinckia sp., Serratia sp., Acinetobacter sp., Microbacterium sp., and Rhizobium sp. Altogether, the present study revealed that Phragmites australis and Chloris virgata growing on petroleum-polluted saline soil in the Yellow River Delta harbor several diverse species of endophytic bacteria and serve as novel sources of beneficial bacteria and hydrocarbon degradation.

The Yellow River Delta wetland is the most integrated, broadest, youngest wetland ecological system in China. Due to the affection by human activities, the wetland is under a degraded risk and urgently require for ecological restoration. Moreover, the wetland is an influenced and responsive region of global change because of its unique water-heat effect and greenhouse gas metabolic process. In this study, five typical salt marsh plant communities were selected to study the characteristics of greenhouse gas emission of the wetland. The results indicated that the greenhouse gas emission, especially for the CO 2 and CH 4 , showed a distinctly spatial variation. The sample site (HW4) discharged the maximum emissions concentration of CH 4 and CO 2 , reaching 691.6 and 1.32 mg/m 3 in the static opaque chamber, respectively. The total annual emissions of CH 4 and CO 2 were approximately 1.20 × 10 4 t a −1 and 18.4 × 10 4 t a −1 in the five plant communities. It was also found that the relationship of the soil moisture to CH 4 emissions was positive correlation, but that to CO 2 emissions was negative correlation. In addition, there was a linear correlation ( y = 0.0196x + 0.0252, R 2 = 0.9872) between the content of Fe and Mn in the soil.

Pollution in urban zoos arises from diffuse and small point sources. However, its control has received little attention in past decades. Online and offline modes of ecological engineering technology were designed to control pollution from small point and diffuse sources in Wuhan City Zoo, China. Their characteristics and performances were investigated in sixteen runoff events from 2003 to 2005. The results showed that the two modes both improved runoff water quality and had high retention rates for water and pollutants. In the outflows, the event mean concentrations (EMCs) of total suspended solids (TSS), chemical oxygen demand (COD), total nitrogen (TN) and total phosphorus (TP) were reduced by 88%, 59%, 46% and 71% for the online mode, and those were 77%, 42%, 50% and 66% for the offline mode. The annual retention rates of pollutant loads for the online mode were 94.9%-98.5% in the three study years; those for the offline mode were 70.5%-86.4%. Based on calculation, the online mode was able to store the runoff of 66.7 mm rainfall completely, and the offline mode could store that of 31.3 mm rainfall. In addition, the online mode can provide an effective way for rainwater utilization and good habitats for aquatic wildlives, and has an excellent aesthetics value for recreationsal pastimes. The offline mode can save land resources and may be an effective and economical measure for diffuse pollution control in urban areas.

Real-time detection of air toxics is becoming increasingly important in understanding the sources and constituents of air pollution. The detection of low levels of air contaminants requires reliable sampling and calibration techniques, as well as sophisticated analytical instrumentation. Recently, a new low pressure chemical ionization (LPCI) source was developed for ambient air monitoring of benzene, toluene, xylene (BTX) and gas-phase polycyclic aromatic hydrocarbons (PAH) in real-time. This ion source in conjunction with a triple quadrupole (Q1, Q2, Q3) mass spectrometer (trace atmospheric gas analyzer (TAGA IIe)) has been proven highly useful for measuring selected air pollutants. The ion chemistry under LPCI conditions involves charge transfer reactions yielding parent ions which are selected in the first quadrupole, Q1, dissociated in the second quadrupole, Q2, and the resultant daughter ions are then identified by the third quadrupole, Q3. Monitoring of specific parent/daughter (P/D) ion pairs is used to measure concentrations of BTX and selected PAH. The response of the TAGA IIe is characterized through multi-point calibration curves. Detection limits (DL) as low as 0.5 microg/m(3) for BTX and PAH were accomplished by optimizing various TAGA IIe operating parameters. This unique method was applied in November 1999 to monitor emissions released during the cleanup of a historical coal tar site in Kingston, Ontario. This information was used by local officials for enhancing abatement activities or in some cases temporarily halting the excavation when levels of air toxics were higher than allowable provincial guidelines.

A miniature flowing afterglow has been constructed and used to study the reactions at 298 K of (CH3)3Si+ with ammonia and several small alkylamines. Rate constants for the disappearance of (CH3)3Si+ are found in general to decrease with increase in the number of alkyl groups on nitrogen. Reaction efficiencies (kreaction/kcollision) are: ammonia 0.73, methylamine 0.73, ethylamine 0.75, dimethylamine 0.68, trimethylamine 0.50, triethylamine 0.46. (CH3)3SiA+ (A = amine) is the major product for all amines except triethylamine which deprotonates (CH3)3Si+. All reaction rate constants are independent of total pressure over the available experimental range of 0.6–1.2 torr. The rate constants for transfer of (CH3)3Si+ between amines show little change with increase in the number of alkyl groups on the participants. The reaction efficiencies for (CH3)3Si+ transfer from the first to the second named of the following pairs are: ammonia/methylamine 0.37, ammonia/dimethylamine 0.40, methylamine/dimethylamine 0.39, methylamine/trimethylamine 0.37, dimethylamine/trimethylamine 0.30. Trimethylamine deprotonates (CH3)3SiNH3+ with an efficiency of 0.79, with negligible competing (CH3)3Si+ transfer. The results demonstrate a consistent pattern of decreasing reaction efficiency in the association of (CH3)3Si+ with alkylamines as the number of alkyl groups in the amines increases but very little effect on the exchange of (CH3)3Si+ between alkylamines. The reaction of (CH3)3Si+ with acetone occurs with greater efficiency (0.80) than for any amine, even though its enthalpy of association is smaller.