Nonpoint sources of volatile organic compounds in urban areas-relative importance of land surfaces and air

Volatile organic compounds (VOCs) commonly detected in urban waters across the United States include gasoline-related compounds (e.g. toluene, xylene) and chlorinated compounds (e.g. chloroform, tetrachloroethane [PCE], trichloroethene [TCE]). Statistical analysis of observational data and results of modeling the partitioning of VOCs between air and water suggest that urban land surfaces are the primary nonpoint source of most VOCs. Urban air is a secondary nonpoint source, but could be an important source of the gasoline oxygenate methyl-tert butyl ether (MTBE). Surface waters in urban areas would most effectively be protected by controlling land-surface sources.     

VOCs和水在Y型分子筛表面的竞争吸附

采用水热处理方法合成了具有不同硅铝比的超稳Y型分子筛,考察了苯、甲苯、二甲苯、苯乙烯和乙酸乙酯与水在Y分子筛表面的竞争吸附。结果表明,随着Si/Al比的增加,Y分子筛表面的有机分子选择性吸附位数量增加,有机分子竞争吸附能力增加。低硅Y型分子筛只有在吸附偶极距>1.0的高极性有机分子时才能与水分子产生有力的竞争吸附,而高硅超稳Y分子筛则对偶极距在0～0.5范围的有机分子就表现出很强的竞争吸附能力。     

Effects of prevalent freshwater chemical contaminants on in vitro growth of Escherichia coli and Klebsiella pneumoniae

Many surface and ground waters in the continental US are contaminated with a variety of chemical pollutants, which are usually present in concentrations in the ppm and ppb range. The effects of these pollutants on coliform bacteria, which are prominent members of the aquatic flora, are poorly understood. Using a microtiter plate assay, isolates of Escherichia coli (from chicken intestine and fresh water), and an isolate of Klebsiella pneumoniae (from bovine milk) were exposed to varying concentrations of common pollutants over a 24 h period. The herbicides/pesticides simazine, atrazine, and diazinon; the VOCs trichloroethene and MTBE; the estrogens estradiol and estrone; and caffeine, all failed to inhibit bacterial growth at ppm levels. Only ethylene glycol, and the herbicide 2,4-D, significantly inhibited bacterial growth compared to controls. These results suggest that the replication of coliform bacteria in fresh waters is not adversely impacted by many common pollutants.     

Response of microcrustacean communities from the surface—groundwater interface to water contamination in urban river system of the Jarama basin (central Spain)

In order to evaluate the water quality at the surface/groundwater interface (hyporheic zone), the pattern of microcrustacean assemblages in response to environmental stress caused by urban industrial contamination was studied in the Jarama River basin (central Spain) during high water discharges (March and April 2011). The clustering of biological variables and the concentration of urban contaminants in hyporheic waters showed that pristine hyporheic waters have moderate species diversity (two to seven species) and dominance of k strategist stygobites, whereas excessively contaminated sites are devoid by crustaceans. An intermediate level of disturbance in hyporheic waters is associated with a peak of species taxonomic diversity (four to nine species) and proliferation of r strategist more tolerant species. Typical species found in hyporheic zone, e.g., Paracyclops imminutus (Copepoda, Cyclopoida), Cryptocandona vavrai (Ostracoda) and Herpetocypris chevreuxi (Ostracoda), were good indicators of high concentrations of Cr, Mn, Ni, Cd, Pb and VOCs; whereas the stygobites do not show any significant correlation. The effectiveness of hyporheic crustaceans as efficient bioindicators for assessing the current ecological status of river ecosystems is emphasised.     

A land use regression model for predicting ambient volatile organic compound concentrations in Toronto,Canada

More than 25 studies have employed land use regression (LUR) models to estimate nitrogen oxides and to a lesser extent particulate matter indicators, but these methods have been less commonly applied to ambient concentrations of volatile organic compounds (VOCs). Some VOCs have high plausibility as sources of health effects and others are specific indicators of motor vehicle exhaust. We used LUR models to estimate spatial variability of VOCs in Toronto, Canada. Benzene, n-hexane and total hydrocarbons (THC) were measured from July 25 to August 9, 2006 at 50 locations using the TraceAir organic vapor monitors. Nitrogen dioxide (NO₂) was also sampled to assess its spatial pattern agreement with VOC exposures. Buffers for land use, population density, traffic density, physical geography, and remote sensing measures of greenness and surface brightness were also tested. The remote sensing measures have the highest correlations with VOCs and NO₂ levels (i.e., explains >36% of the variance). Our regression models explain 66–68% of the variance in the spatial distribution of VOCs, compared to 81% for the NO₂ model. The ranks of agreement between various VOCs range from 48 to 63% and increases substantially – up to 75% – for the top and bottom quartile groups. Agreements between NO₂ and VOCs are much smaller with an average rank of 36%. Future epidemiologic studies may therefore benefit from using VOCs as potential toxic agents for traffic-related pollutants.     

Measurements of non-methane hydrocarbons, DOC in surface ocean waters and aerosols over the Nordic seas during polarstern cruise ARK-XX/1 (2004)

To explore processes leading to the formation of volatile organic compounds at the sea surface and their transfer to the atmosphere, whole air, marine aerosols, and surface ocean water DOC were simultaneously sampled during June-July 2004 on the Nordic seas. 19 C(2)-C(6) non-methane hydrocarbons (NMHCs) in the air samples are reported from nine sites, spanning a range of latitudes. Site-to-site variability in NMHC concentrations was high, which suggests variable, local sources for these compounds studied. Total DOC in surface waters sampled ranged from 0.84 mg l(-1) (Fram Strait) to 1.06 mg l(-1) (East Greenland Current), and decreased 6-8% with 24h UV-A irradiation. Pentanes and hexanes, as well as acetone and dimethylsulfide, were identified in the seawater samples using solid-phase microextraction/GC-MS. All these compounds are volatile enough that exchange with the atmosphere can be expected, and the detection of the hydrocarbons in particular is consistent with a marine source for these in the air samples. Size-fractionated aerosols from the same sampling regions were analysed by SEM-EDX and contained sea salt, marine sulfates, and carbonates. A culturable bacterium was isolated from the large (9.9-18 microm) fraction at one site, and identified by 16S rRNA PCR analysis as Micrococcus luteus, raising the possibility that marine bioaerosols could transfer marine organic carbon to the aerosol phase and thus influence formation of VOCs above the remote oceans.     

Solubility of volatile organic compounds in aqueous ammonia solution

The Ostwald solubility coefficient, L of 17 volatile organic compounds (VOCs) from the gas phase into water and dilute aqueous ammonia solutions was determined by the equilibrium partitioning in closed system-solid phase micro extraction (EPICS-SPME) method at 303 K and at 0-2.5 mol dm(-3) ammonia concentrations. Ammonia increased the solubility of all VOCs nearly linearly, but to a different extent. The difference in the solubility values in aqueous ammonia solutions (Lmix) compared to pure water (L) is explained on the basis of a Linear Solvation Energy Relationship (LSER) equation made applicable for solvent mixtures, logLmix - logL = x((sNH3 - sH2O)pi2H + (aNH3 - aH2O)Sigma2H + (bNH3 - bH2O)Sigmabeta2H + (vNH3 - VH2O)Vx). sNH3 - sH2O, aNH3 - aH2O, bNH3 - bH2O, vNH3 - vH2O are the differences of solvent parameters, x is the mole fraction, pi2H is the solute dipolarity-polarizability, Sigmaalpha2H is the effective hydrogen bond acidity of the solute, Sigmabeta2H is the effective hydrogen bond basicity of the solute and Vx, the McGowan characteristic volume. The most significant term was v, the phase hydrophobicity. The solubility behavior was explained by the change in structure of the aqueous solution: the presence of ammonia reduces the cavity effect. These findings show that the presence of compounds such as ammonia, frequently observed in environmental waters, especially wastewaters, affect the fugacity of VOCs, having consequences for the environmental partitioning of VOCs and having technical consequences towards wastewater treatment technologies.     

The hydrochemistry of surface waters in andesitic volcanic area, Norikura volcano, central Japan

Many hydrochemical studies have been reported on surface waters and a major contributor of the water chemistry is considered to be rock dissolution. However, the extent of rock dissolution effect on surface water chemistry has still not been fully understood. The purpose of this research is to clarify the effect to give better understanding on the nature of surface water chemistry. Natural surface water samples were collected from a typical andesitic volcanic area, and major chemicals were investigated in terms of water-rock interaction. The analytical results were subjected to multivariate statistical techniques to understand the geographical distribution and to extract geochemical potential factors affecting the chemical concentration of waters. High correlation between the major chemicals and the altitude of sampling points was found among non-geothermal waters. The mole ratios of summation Sigmacations/Si were significantly high in meteoric waters (2.5), low in the surface waters from the summit area of the volcano (0.4), and the median in the surface waters at the mountainside region (1-2) and in geothermal waters (1-2). The basement rocks around the observation areas showed a relatively low ratio (0.4). On the basis of the water chemical compositions, these chemical variation were quantitatively interpreted by the incongruent dissolution reactions for primary minerals in the basement rocks followed by the formation of secondary minerals. The variations of Na+/(Ca2+ + Na+) ratio took positive correlation with [Si] for the non-geothermal waters, and high linear correlation was observed between log(a(Ca2+)/a2(H+)) and log(a(Na+)/a(H+)). These relations were interpreted by an ion-exchange reaction. The factor analysis (FA) gave two major factors to describe the chemical behaviors mentioned above. The contribution proportionate for each factor was calculated as; 65% was the incongruent rock dissolution, and 16% was the ion-exchange reaction.     

Priority volatile organic compounds in surface waters of the southern North Sea

The occurrence of 25 volatile organic compounds (VOCs) was studied from April 1998 to October 2000 in the southern North Sea. Target VOCs were selected from lists of priority pollutants for the marine environment and included, e.g., chlorinated short-chain hydrocarbons (CHCs), monocyclic aromatic hydrocarbons (MAHs), and chlorinated monocyclic aromatic hydrocarbons (CMAHs). Water samples were taken from the Channel, the Belgian Continental Shelf, the mouth of the Scheldt estuary and the Southern Bight, and were analysed by purge-and-trap and high-resolution gas chromatography-mass spectrometry. All data were produced by analyses deemed 'in control' by a rigorous quality assurance/quality control program provided by QUASIMEME (Quality Assurance of Information for Marine Environmental Monitoring in Europe). Chloroform and trichloroethene were commonly detected at concentrations up to 1900 and 270 ng l(-1), respectively. The other CHCs were generally found below 5 ng l(-1), and rarely exceeded 10 ng l(-1). Concentrations of MAHs were at least one order of magnitude higher than those of the CHCs. The higher levels were attributed to anthropogenic emissions from oil-related activities in coastal areas. CMAHs, except chlorobenzene and 1,4-dichlorobenzene, were hardly detected in North Sea waters. The levels of several CHCs and MAHs were shown to decrease compared to previous investigations in 1994-1995, probably as a result of on-going emission reduction efforts. The occurrence of 1,1,1-trichloroethane, for instance, was substantially reduced since the Montreal Protocol was implemented in 1995.     

Photocatalytic purification of volatile organic compounds in indoor air: A literature review

Volatile organic compounds (VOCs) are prevalent components of indoor air pollution. Among the approaches to remove VOCs from indoor air, photocatalytic oxidation (PCO) is regarded as a promising method. This paper is a review of the status of research on PCO purification of VOCs in indoor air. The review and discussion concentrate on the preparation and coating of various photocatalytic catalysts; different kinetic experiments and models; novel methods for measuring kinetic parameters; reaction pathways; intermediates generated by PCO; and an overview of various PCO reactors and their models described in the literature. Some recommendations are made for future work to evaluate the performance of photocatalytic catalysts, to reduce the generation of harmful intermediates and to design new PCO reactors with integrated UV source and reaction surface.     

A retrospective assessment of gold mining in the Reedy Creek sub-catchment, northeast Victoria, Australia: residual mercury contamination 100 years later

The mining of gold can lead to toxic metals such as mercury (Hg) contaminating watercourses as by-products. The Reedy Creek sub-catchment, in northeast Victoria, Australia, was mined for gold in the 1850s. In 1998, samples were taken from six watercourses to measure any remaining toxic metal contamination in sediments and surface waters from two creeks with no previous gold mining (controls) and four that were mined. Although mean concentrations of Hg (measured using an ICP-OES) in sediments were below worldwide background levels, individual sites along Reedy Creek had slightly elevated Hg concentrations. In contrast, the Hg concentrations in the surface waters were above background levels. Temporal fluxes of very high Hg concentrations in the surface waters during periods of first flow and flood events revealed that Hg concentrations in the surface waters may, at certain times of the year, exceed all Australian and New Zealand Environment and Conservation Council (National Water Quality Management Strategy. Australian Water Quality Guidelines for Fresh and Marine Waters, ANZECC, 2000) guidelines for water use and the protection of the aquatic ecosystem.     

Polycyclic aromatic hydrocarbons in rainwater and surface waters of Lake Maggiore, a subalpine lake in Northern Italy

Fourteen polycyclic aromatic hydrocarbons (PAHs) were measured in surface waters and precipitation inputs to Lake Maggiore, a subalpine lake in Northern Italy, from July 2003 to January 2004. Particulate and dissolved phases in surface water and rain samples were determined. Analyses of PAHs were performed using XAD-2 resin to isolate the dissolved PAHs and subsequent extraction by accelerated solvent extraction (ASE). Both the dissolved and particulate phase PAH patterns in surface water and rainwater samples were dominated by the low molecular weight compounds (e.g., phenanthrene, fluoranthene and pyrene). More than 85% of PAHs in surface waters and 72% of PAHs in rainwater were associated to the dissolved phase. The SigmaPAH concentrations in surface waters (particulate and dissolved phases) were 0.584 +/- 0.033 ng l(-1), 2.9 +/- 0.312 ng l(-1) and in rainwater (particulate and dissolved phases) 27.5 +/- 2 ng l(-1), 75.4 +/- 9 ng l(-1), respectively. Temporal variability of PAH concentrations in rain and surface water samples were observed, with higher concentrations in November and December, coinciding with the largest precipitation amounts. The comparison of PAH signatures in rainwater and surface waters seems to indicate that wet deposition (2.5-41 microg m(-2) month(-1)) is the main source of PAH contamination into surface waters of Lake Maggiore.     

Longitudinal variations in indoor VOC concentrations after moving into new apartments and indoor source characterization

This study examined the indoor concentrations of a wide range of volatile organic compounds (VOCs) in currently built new apartments every month over a 24-month period and the source characteristics of indoor VOCs. The indoor total VOC (TVOC) concentrations exhibited a decreasing tendency over the 24-month follow-up period. Similar to TVOCs, the median indoor concentrations of 33 of 40 individual VOCs (all except for naphthalene and six halogenated VOCs) revealed decreasing tendencies. In contrast, the indoor concentrations of the six halogenated VOCs did not reveal any definite trend with time. Moreover, the indoor concentrations of those halogenated VOCs were similar to the outdoor concentrations, suggesting the absence of any notable indoor sources of halogenated VOCs. For naphthalene (NT), the indoor concentrations were significantly higher than the outdoor concentrations, suggesting the presence of indoor NT source(s). The floor/wall coverings (39 %) were the most influential indoor source of indoor VOCs, followed by household cleaning products (32 %), wood paneling/furniture (17 %), paints (7 %), and moth repellents (5 %).     

Validation of in-situ measurements of volatile organic compounds through flask sampling and gas chromatography/mass spectrometry analysis

Continuous monitoring of ambient non-methane hydrocarbons (NMHCs) by automated gas chromatographs equipped with flame ionization detection (termed in-situ GC/FID) with hourly data resolution was instated in ozone non-attainment areas throughout Taiwan. Performance of these on-site in-situ GCs was validated by manual flask sampling, as well as by in-lab gas chromatography/mass spectrometry (GC/MS) analysis. More than 50 VOCs from C₂ to C₁₁ were analyzed by both methods. Ninety flask samples were collected in series near an in-situ GC monitoring station in order to closely compare with the in-situ measurements. Both time-series and scatter plots from the two methods are displayed and discussed. It was found that over-simplified, un-humidified single-point calibration leading to surface loss was responsible for the bias in the in-situ method, resulting in greater error in accuracy as VOC volatility decreased. Although this over-estimate of the concentrations was found across all target VOCs, both methods were able to consistently capture the variability of ambient VOCs, with R² values greater than 0.9 for most of the major VOCs.     

Weekday/weekend differences in OH reactivity with VOCs and CO in Baltimore, Maryland

This study compared the first-order frequencies for OH associated with volatile organic compounds (VOCs) and CO (hereafter called OH reactivity with VOCs or CO), the product of the VOC or CO concentration, and their respective kOH value, on an average weekday with that on an average weekend day at a core urban site in Baltimore, MD. The average daytime concentrations were calculated for each of the 55 available Photochemical Assessment Monitoring Station (PAMS) VOCs using data from the Baltimore site. The data were sorted in descending order to highlight the important species based on concentration. The OH reactivity with VOCs was sorted in descending order to identify the important species based on the magnitude of the OH reactivity. A similar process was followed for the OH reactivity with CO. The contribution of the significant species to the weekday/weekend difference in OH reactivity was examined. The OH reactivity with C5H8 was the largest among the OH reactivity with the PAMS' VOCs and was the same on the weekday and weekend. The weekday/weekend difference in OH reactivity with VOCs was entirely due to differences in concentrations of the anthropogenic VOCs. The OH reactivity with VOCs was 11% larger on the weekday. When OH reactivity with CO was included, the OH reactivity was 13% larger on the weekday.     

A study on dynamic volatile organic compound emission characterization of water-based paints

Volatile organic compounds (VOCs) emitted from surface coatings have caused growing public concern for air quality. Even the low-emitted VOC impact from water-based paints on indoor air quality in urban areas has caused concern. This paper presents experimental data using a mathematical model to simulate dynamic VOC emissions from water-based paints that is based on mass transfer and molecular diffusion theories. A series of field-analogous experiments were carried out to continuously measure the VOCs emitted from two typical water-based paints using a gas chromatography-flame-ionization detector monitor in an artificial wind tunnel system. In the study cases, the mass flux of VOCs emitted from the water-based paints was up to 50 microg/m2sec. It was found that the time needed to completely emit VOCs from water-based paints is just hundreds of seconds. However, the order of magnitude of the VOC emission rate from water-based paints is not lower than that from some dry building materials and solvent-based paints. The experimental data were used to produce a useful semiempirical correlation to estimate the VOC emission rates for water-based paints. This correlation is valid under appropriate conditions as suggested by this work with a statistical deviation of +/- 7.6%. With this correlation, it seems feasible to predict the dynamic emission rates for VOCs during a painting process. This correlation is applicable for assessing the hazardous air pollutant impact on indoor air quality or for environmental risk assessment. Associated with the dynamic VOC emission characterization, the air-exchange rate effect on the VOC emission rates is also discussed.     

天津市挥发性有机物污染特征与来源及其O3生成潜势

为深入了解天津市大气挥发性有机物(VOCs)来源及对O3的影响,基于2020年天津市VOCs在线监测数据,统计分析了VOCs污染特征,用主成分分析法对天津市VOCs的来源进行解析,用最大增量反应活性法分析VOCs的O3生成潜势(OFP).结果表明:2020年天津市VOCs的年均质量浓度总和为56.56μg/m3,其中,...     

Emission,speciation, and evaluation of impacts of non-methane volatile organic compounds from open dump site

Surface emission from Dhapa, the only garbage disposal ground in Kolkata, is a matter of concern to the local environment and also fuels the issues of occupational and environmental health. Surface emission of the Dhapa landfill site was studied using a flux chamber measurement for nonmethane volatile organic compounds (NMVOCs). Eighteen noncarbonyl volatile organic compounds (VOCs) and 14 carbonyl VOCs, including suspected and known carcinogens, were found in appreciable concentrations. The concentrations of the target species in the flux chamber were found to be significantly higher for most of the species in summer than winter. Surface emission rate of landfill gas was estimated by using two different approaches to assess the applicability for an open landfill site. It was found that the emissions predicted using the model Land GEM version 3.02 is one to two orders less than the emission rate calculated from flux chamber measurement for the target species. Tropospheric ozone formation has a serious impact for NMVOC emission. The total ozone-forming potential (OFP) of the Dhapa dumping ground considering all target NMVOCs was estimated to be 4.9E+04 and 1.2E+05 g/day in winter and summer, respectively. Also, it was found that carbonyl VOCs play a more important role than noncarbonyl VOCs for tropospheric ozone formation. Cumulative cancer risk estimated for all the carcinogenic species was found to be 2792 for 1 million population, while the total noncancer hazard index (HI) was estimated to be 246 for the occupational exposure to different compounds from surface emission to the dump-site workers at Dhapa.

Implications:This paper describes the real-time surface emission of NMVOCs from an open municipal solid waste (MSW) dump site studied using a flux chamber. Our study findings indicate that while planning for new landfill site in tropical meteorology, real-time emission data must be considered, rather than relying on modeled data. The formation of tropospheric ozone from emitted NMVOC has also been studied. Our result shows how an open landfill site acts as a source and adds to the tropospheric ozone for the airshed of a metropolitan city.     

Estimation of volatile organic compounds in Kuwaiti houses after the Gulf war

Interest in indoor air quality is steadily increasing. Exposure to volatile organic compounds (VOCs) is associated with health effects as diverse as childhood respiratory disease, lung cancer and cardiovascular disease. In an effort to assess the environmental impact indoors from possible sources of VOCs, such as (i) open oil lakes, (ii) chemical and petrochemical industries and (iii) indoor pollution from household items, concentrations of aliphatic and aromatic VOCs, comprising n-hexane to n-hexadecane, benzene, toluene, xylene, ethyl benzene, methanol and o-dichlorobenzene, were measured in indoor air samples from seven different cities in Kuwait using a gas chromatograph. The data for the period March to May 1993 are presented. The VOCs, as measured, were surprisingly low and they are below the concentrations set by the American Hygienists Association. However, although the concentration of the estimated VOCs being low, were cumulative effects of them entering the human body and water sources cannot be ruled out.     

Sorption of organic gases in residential rooms

Experiments were conducted to characterize organic gas sorption in residential rooms studied “as-is” with furnishings and material surfaces unaltered and in a furnished chamber designed to simulate a residential room. Results are presented for 10 rooms (five bedrooms, two bathrooms, a home office, and two multi-function spaces) and the chamber. Exposed materials were characterized and areas quantified. A mixture of volatile organic compounds (VOCs) was rapidly volatilized within each room as it was closed and sealed for a 5-h Adsorb phase; this was followed by 30-min Flush and 2-h closed-room Desorb phases. Included were alkane, aromatic, and oxygenated VOCs representing a range of ambient and indoor air pollutants. Three organophosphorus compounds served as surrogates for Sarin-like nerve agents. Measured gas-phase concentrations were fit to three variations of a mathematical model that considers sorption occurring at a surface sink and potentially a second, embedded sink. The 3-parameter sink–diffusion model provided acceptable fits for most compounds and the 4-parameter two-sink model provided acceptable fits for the others. Initial adsorption rates and sorptive partitioning increased with decreasing vapor pressure for the alkanes, aromatics and oxygenated VOCs. Best-fit sorption parameters obtained from experimental data from the chamber produced best-fit sorption parameters similar to those obtained from the residential rooms.