Atmospheric Pollution - Science topic

Bonjour, il existe un spectromètre spatial IASI avec ses 8461 canaux spectraux qui observe CO2 dans 15um et 4.3um bandes spectrales, mais il faut comprendre que la taille du pixel IASI est environ 12km et si les sources sont petites on ne verra pas une grande différence. Pour une telle comparaison, il faut trouver une zone qui est "propre" aujourd'hui et qui sera polluée suite à l'industrialisation. Ensuite, il faut choisir les scénarios atmosphériques très ressemblants (ciel clair, température similaire, etc) et comparer les rayonnements dans les canaux CO2 dont la fonction de contribution a un maximum proche à la surface. Peut-être qu'il sera judicieux de faire la même comparaison pour une zone rurale qui n'est pas et ne sera pas polluée.

Hello Dariusz: Just this morning I read about this episode in the Los Angeles Times. The article was written from the point of view of German environmental agencies and a political exchange with the Polish government. The impression I got was that the source of the toxins and a reasonable list of the toxins has not yet been determined. If that's true, then, the first order of business is the identification of the problem and its source(s). It sounded like the problem is a complex one. Polish and German scientists must been collaborating before June. What do those folks have to say? Best regards, Jim Des Lauriers

The following link is also very useful:

It is often poor, and the environment is subjected to daily deterioration due to the large number of factories and other things that have developed at the present time

Dear Anton Vrdoljak,

Thanks for your post and beautiful photos.

Greetings,

Dariusz Prokopowicz

It seems that the COVID-19 has positive effects on plants and air purification.

I have a field observation that reduced emissions from factories reduced soot and dust on plant leaves, thus improving their growth and thus increasing oxygen releases.

I wish you good luck

In recent days we have noticed good things about the climate and the environment. For example, there has been a marked improvement in air quality. A two-month global break has shown a reduction in carbon dioxide and nitrogen dioxide (NO2) emissions. Knowing that air pollution has a significant effect on the climate.

The direct greenhouse gases are carbon dioxide (CO2), nitrous oxide (N2O), and methane (CH4). The indirect greenhouse gases are non-methane volatile organic compounds (NMVOCs), nitrogen oxides (NOx) comprised of nitrogen monoxide (NO) and nitrogen dioxide (NO2), sulfur dioxide (SO2), and carbon monoxide (CO).

Hi... Yash

Aerosol Direct Radiative Forcing (ADRF) depicts the scattering and absorption of solar radiation by aerosols. the positive values of ADRF indicate the warming and negative values indicate the cooling.

I hope that you have calculated ADRF using up and down radiative flux values. SBDART only provides up and down radiative fluxes later you have to calculate radiative forcing using those values. This method is already published by the many aerosol experts. You can refer to those publications.

Estimated TOA and SFC ADRF indicated the change in flux at TOA and SFC by aerosols. ADRF in the ATM indicates the change in flux within the atmosphere.

Further, you can more clearly associate these estimated radiative forcing to the climate by calculating heating rate. heating rate depicts the warming of the atmosphere. This can easily associate with regional or global climate change.

Herewith I have given you a very basic idea, but I will suggest you to read the related publication and their interpretation. This will give you more idea.

Hope this will help. Feel free to ask me, if you have anything

I think to answer the first part of your question we should consider different criteria such as urban policy, urban economics, urban climate, etc. Regarding the second part of your question, I think it would be important to consider the feature of urban green spaces like the cooling effect of urban green spaces, which has a significant role to improve the physical and psychological health of residents.

I have two studies in this case maybe that would be useful for you.

Dear Kishore Ragi

Inventing of the artificial chemistry is definitely to be avoided if we want our models to have any relation to the real atmosphere. This problem was discussed by Heymann (2010): Lumping, testing, tuning: The invention of an artificial chemistry in atmospheric transport modeling (Studies in History and Philosophy of Science Part B: Studies in History and Philosophy of Modern Physics)

The paper was published in the special issue dedicated to modeling and simulation in the atmospheric and climate sciences and the text is available on request in the RG system.

Considering the complexity of the problem it is indeed very wise to perform first the detailed kinetic studies (both theoretical and experimental) followed by the rational compression of the chemical mechanism. In this area I would like to suggest Sportisse (2000): Reduction of Chemical Kinetics in Air Pollution Modeling., J. Comp. Physics, Vol 164, issue 2, p 354–376

The reality of chemical modeling is that some atmospheric chemistry models still use the outdated lumping methods. It is indeed an excellent idea to revisit these problems.

You can take good ideas and informations about that in this paper:

You may find the link below:

Hi Valerio,

I am sure you must have figured out a solution by now (since you posted the question 2 years back). However, here is what I found useful for calculating PBLH using the sounding data from the above mentioned website. Observed Diurnal Cycle Climatology of Planetary Boundary Layer Height, Liu, Shuyan; Liang, Xin-Zhong, Journal of Climate, vol. 23, issue 21, pp. 5790-5809. The authors have used a FORTRAN code that they developed for calculating PBLH using the sounding data.

Vehicle Emissions

Vehicle emissions are another source of fossil fuel emissions and air pollution. Private transportation accounts for about 10 percent of your carbon footprint, or the amount of carbon dioxide your lifestyle and activities contribute to the atmosphere, reports Carbon Footprint Ltd.

Industry

Industry is a major contributor to air pollution. Industrial processes release pollutants such as nitrous oxide and hydrofluorocarbons into the air. Agricultural practices, livestock rearing and landfills also contribute to atmospheric methane concentrations. The overall effect is an increase in the global warming potential.

Deforestation

Deforestation affects the atmosphere in several ways. Forests act as sinks for carbon dioxide through a process called carbon sequestration. Trees store carbon dioxide in their plant tissue as they take in this gas to undergo food-making. In effect, this action removes carbon dioxide from the air. When forests are burned and destroyed, this storage area for carbon dioxide is removed, increasing the concentrations of atmospheric carbon dioxide.

Wood Fires

Wood fires cause air pollution by releasing particulate matter into the air. These particles can become lodged in your respiratory system, causing irritation to tissues. The particles can also aggravate existing health conditions such as asthma, warns the U.S. Environmental Protection Agency.

Smoking

You are still at risk of the dangers of smoking even if you are a nonsmoker. The University of Minnesota estimates that up to 90 percent of the American population is routinely exposed to secondhand smoke. Tobacco smoke contains 40 carcinogens, making it an especially lethal form of air pollution.

Dear Tabish and Janusz

Primary particles are directly emitted by processes such as biomass burning, incomplete combustion of fossil fuels, volcanic eruptions, and wind-driven or traffic-related suspension of road, soil, and mineral dust, sea salt. Also biological aerosols are important  and often ognored (plant fragments, microorganisms, pollen, etc.) and considered as primary aerosols. Secondary aerosols  are formed by gas-to-particle conversion in the atmosphere (new particle formation by nucleation and condensation of gaseous precursors). You can also have a mixture of both as biological micro-organisms can stick on SOA (mixture of primary and secondary aerosols). One kind of  hybrid is called polluen (pollutant + pollen) (see http://www.jle.com/fr/revues/ers/e-docs/synergie_entre_pollens_et_polluants_chimiques_de_l_air_les_risques_croises_130005/article.phtml). This mixture is rarely considered.

Concerning oxidized nitrogen only NO (nitrogen monoxide) and N20 (nitrous oxide) are directly emitted in the atmosphere. Particles of NO3-  is formed through reactions in the atmosphere and is therefore a secondary aerosol.

Concerning reduced nitrogen, only NH3 is produced and NH4+ is obtained through oxidation and therefore is a secondary aerosol also. Same for sulfates.

Sulfate, nitrate, and ammonium are important inorganic constituents of urban aerosol particle and account for 30-70% of PM2.5. Through filter packs , it is  possible to identify these species. However, there are numerous challenges ( see

Ref: https://link.springer.com/article/10.1007/s11430-014-4986-)

In fact, accurate determination of the chemical composition of air particulate matter is a formidable analytical task.  (see Poesch p 7523 near the bottom, i.e. refered by Janusz above )

So the bottom line is a knowledge of which species is primary and which is secondary is helpful but not sufficient given the complexity of the problem (contamination by biological particles, formation of hybrid, etc.). Actual technique cannot resolve everything.

My hope in the future is that a particularly challenging application of aerosol mass spectrometry develops, i.e. the one with high relevance for public health and security is the identification of biological particles and pathogens (bacteria, viruses, spores, etc.). i.e primary and secondary mixed aerosols.

Hope it helps

Alain

Well, plotting data of each pollutant concentration with time, and plotting the concentration of same source pollutant in the same time can be shown best correlation.

good day

Hello, I think yes, because any continuous time series can be discretised and analyzed as a discrete time series. But you must look at the long of your time series because of you need to apply statistical tools among others tools. Also you should keep in ind if the time series is linear or nonlinear. For instance, Pm2.5 and PM10 concentrations are nonlinear and you should work with carefully!

To really understand your correlation, you need to allow for the vertical turbulent structure of the boundary layer, which maximises in most circumstances through daylight hours because of solar heating. At night, radiative cooling tends to lower the height of the boundary layer, leaving less air to dilute the traffic emissions. One way to do it statistically is to characterise all visible cycles and subtract them from the data: the diurnal weekly and seasonal cycles of winds, temperature etc which are meteorological, and of the traffic flow which is anthropogenic. The results may be useful statistically, but need to be viewed with caution from the point of view of scientific understanding.

Your question leaves me with several question marks. Are you looking into dispersion of airborne particles (transport equations with particles' settling speed)? Or are you looking into erosion by atmospheric wind?

There are virtually hundreds of different dispersion models around. If you look at the top of the page, it says: "This annex documents simple models for first estimation or screening." And that's what it is.

For instance, Model C is applicable on roads with complete obstruction by buildings on both sides of the road. Model D does not consider any buildings. A real dispersion situation will be somewhere in between. And the dominant wind direction will not be in a 90° angle to the road and... The selection of a suitable model depends on the situation you want to analyse. And on the level of detail you want to (or have to) achieve.

I have gathered a list of Papers on GHG emissions from bioenergy related land-use, which is somewhat related to your question: https://agwobserver.wordpress.com/2014/03/10/papers-on-ghg-emissions-from-bioenergy-related-land-use/

Carlos,

Here are several references that could help you:

Regards

Rishu:

It is not surprising to obtain such significant difference in PM10 and PM2.5 levels. The haul road (unpaved surface)  is likely to generate larger particle sizes that may fall within PM10 range. The 23 ug/m3 PM2.5 might probably come from vehicle/haul truck exhaust and very fine airborne dust that are 2.5 microns and below. You are more than likely to obtain higher concentrations than observed for PM10 if you do Total Suspended Particulate (TSP) measurements. Airborne dust emitted from haul roads are likely to have larger sizes than PM10. So in effect, you will observe the order of concentrations of particulates (descending order) as TSP, PM10, PM2.5 with significant differences among them.

Thank all of your ideas! I also found an interesting literature on this if anyone would be interested to read: 

McDonnell, J. J., & Beven, K. (2014). Debates—The future of hydrological sciences: A (common) path forward? A call to action aimed at understanding velocities, celerities and residence time distributions of the headwater hydrograph. Water Resources Research, 50(6), 5342-5350.

Dear Michal

The Dr  Sébastien Vaesen's answer is completely perfect 

Dear Nada,

Please do your homework before asking for help from your colleagues. A quick search on the Web for "mathematical modeling of air pollution" led to over 1,200,000 results, many of which are papers you can access freely.

If you are overwhelmed by the number of sources available, then start from the IPCC 5th assessment report, available from https://www.ipcc.ch/report/ar5/. And if you'd like to focus on an open source journal which published a number of papers on that topic, then look first at Atmospheric Chemistry and Physics (ACP), which is available from http://www.atmospheric-chemistry-and-physics.net.

Even books and book chapters that review this question are downloadable from the Internet: see http://envirocomp.org/books/chapters/2aap.pdf and http://www.eolss.net/sample-chapters/c02/E6-03B-04-04.pdf, for instance.

Regards, Michel.

MOPITT:https://eosweb.larc.nasa.gov/project/mopitt/mopitt_table

OMI:http://aura.gsfc.nasa.gov/scinst/omi.html

Questioner

We provide you answers; thus (please) make an effort to comment!

In carbon trading mechanisms, the global warming impact of other gases (e.g. methane and nitrous oxide) are expressed in terms of CO2 equivalents.

The conversion factors are: 25 for CH4 and 298 for N2O (over 100-year time span).

This means that the impact of 1 kg of CH4 is similar to 25 kg CO2 equivalents and the impact of 1 kg of N2O is similar to 298 kg of CO2 equivalents over 100-year time span.

Hans Puxbaum is right, the relation with health hazards is weak, at least effects by inhalation. Although some indirect effects can be expected, for instance by uptake of deposited metals in vegetables, or by ingestion of polluted soil by children. But than again, this effect is uncertain.

If you can read German (perhaps with a bit of help of Google translate?), some more information is available at the sites of LANUV, the State Agency for Nature, Environment and Consumer Protection of North Rhine-Westphalia in Germany. Here are some links (Staubniederschlag is dust depostion):

http://www.lanuv.nrw.de/umwelt/luft/immissionen/staubniederschlag/ with background information, a short description of the Bergerhoff method, German norms for 5 metals and buttons to Messnetz( measurement network):

with indications of possible applications of the method like Hans Puxbaum meant,

and Messergebnisse (Measurement results):

with annual and trend publications on dust deposition and its components like Pb, Cd, As, Ni, Tl, Hg, and dioxins, furanes and PCB's.

Hope this helps!

Greetings,

Marcel Severijnen

Something like this one?

An industrial thumb rule is 8 - 12 liters/m2 FAD of Bag Area

Air is the best oxidant without any doubt. 

With respect to your comments particularly about sulfate, another important source is sea salt, in which the concentration of this ion is usually around 10%, according to the SPECIATE database (Profile Number: 4310110). It is also well known that this ion is already present in seawater, due to the oxidation of Dimethyl Sulfide (DMS) emitted by phytoplankton, so it is definitely emitted as a primary aerosol, in this case.

Dear Saifeldin,

The following publications may be helpful:

Rafik

There has been rapid growth in the use of apps to get access to autorickshaws in Bangalore. I suspect that this is happening in other big cities of India in parallel. A app-based-cabs company has been including autorickshaws in its menu for more than a year. Their pricing technique has now proved very successful. We pay a "convenience charge" of Rs 10 (equivalent to about 15 US cents) over the meter indication. The driver seems to keep Rs 5 and the app company takes the other 5. I find it is very easy to get autos anytime I want in Bangalore to go anywhere.  Technology and transparency enabled by it have achieved what policing has failed to achieve over decades. 

Another convenience: I am able to pay in cash, or out of a digital wallet run by the company. As a result, I don't have to worry about the driver saying he has no change.

The question is a very deep one. As at now I don't think anyone has carried out a research on that, but i do know that most of the freshwater systems in the world are getting polluted day in day out. With freshwater constituting less than 3% of the water in the world and more than 1% of that existing in solid (ice) form, burning of ammunition will certainly have a toll on freshwater since that is what farmers depend on in agriculture. Burning of ammunition leaves traces of poisonous and radioactive elements such as uranium  in the earth crust. Ultimately, when it rains, two negative things happen. There is streamflow into rivers, lakes and other water bodies on which agriculturists depend on for irrigation purposes. This deteriorates the soil structure and affects the growth of plants. Secondly, some of these elements are leached and this can also affect groundwater. However, this is less serious as sometimes groundwater is too deep to be reached.

The Middle East has the highest concentration of wars in the world, therefore most of the water bodies in the countries that engage in wars have their freshwater systems degraded. Apart from that, livestock are also destroyed. All this have a toll on agriculture and since burning of ammunition is frequent in such places, the contamination is also drastic.

We tend to use heights of between 200-500m for our back trajectory analyses. These elevations are well within the convective boundary layer during the day, but above the nocturnal boundary layer under most conditions. This means that, if you are trying to look at source/fetch regions corresponding to measurements made near the surface, then relating back trajectories to observations made between about 10am and 5pm each day (when mixing is fairly strong, and near surface measurements are representative of most of the CBL) is OK. At night, however, under all but the most windy and well mixed of conditions, any near surface measurements you make are likely to be partially (or completely) decoupled from what is happening aloft in the residual layer (200-500m). Under these situations, your measurements will have a fairly restricted "footprint" and the trajectories you calculate may not be related to this fetch at all (particularly in regions of uneven terrain where nocturnal drainage flows may occur under stable conditions). Cheers, Scott.

Yes

Hello Gerard,

 In your extensive analysis you did not include the fact that the Greek population is well educated and aware of the natural dangers that hit all too common for millennia. Although the country is short of money, many research projects are funded from EE and elsewhere, so there is not a big increase of risks since 2008.  You see some of the projects mentioned above.

For example, the Greek people were well aware of tsunamis before Dec. 2004, unlike most of the rest of the world. I think Greek people are better prepared than those in Canada by comparison. In the last 10 years or so the federal funding for anything to do with the environment including research at universities in Canada has been severely CUT to avoid people get the facts on weather, natural disasters, etc. The reason is the government has been extremely pro-fossil fuel with a “forget the environment” attitude (also was the only country to officially return its signature from the Kyoto Protocol).  The result is a big problem for preparedness in a developed country and a worry for those trying to educate the public/schools, etc

Dear Naveen,

Please go through the attached research article, may be helpful to you.

 Dear Dayana, please look here (par 5.3).

Cheers Valerio

If  CAM model simulations use prescribed aerosol data, it means that these simulations do not consider the impact of atmosphere on aerosol, but include the impact of aerosol on atmosphere (cloud and radiation).    Note that the prescribed aerosol data used in CAM model considers the impact of atmosphere on aerosol.     Therefore, it's hard to say the radiative forcing of aerosols is underestimated because the aerosols are prescribed in the model. 

Hi Waqar,

The uncertainties for each PAH species should be determined as part of your analytical method. Presumably you have quantified your PAHs using some GC/MS variant so there will be plenty of literature out there about how different groups have calculated uncertainty. The USEPA would also likely have a guide for quantifying uncertainty for the analysis of PAHs because there is a standard method. Your analytical method should also produce MDLs which can be used to calculate uncertainties for those samples below the MDL. I would highly recommend reading: 

which should give you an idea how to treat your data. To answer your other question, depending on how your uncertainty is calculated, you may have one value for each PAH, or you may have a different value for each PAH in each sample.

A few things appear a bit problematic with your wider study. First, 52 samples is quite low for a source apportionment study. Typically you would want more than 100 samples. Obviously sampling for longer may not be possible all the time, but the small number of samples could cause problems. More concerning for me is your attempt to apportion PAHs. I know in the literature this is widely reported, but care should be taken before you embark on this. I recommend reading: 

Galarneau, E. 2008. Review: source specificity and atmospheric processing of airborne PAHs: implications for source apportionment. Atmospheric Environment, 42: 8139-8149.

This paper highlights a number of problems with trying to apportion PAHs, most notable of which is that PAHs do not satisfy the most basic "rules" of receptor modelling. The arguments against trying to apportion PAHs are well-presented in the paper and may convince you to try using your data another way.

I hope this information helps and good luck with your work.

Travis

Please explain your question a little more in depth.  You will have water gas shift, methanation and possibly some  higher HC chains formed, Boudouard reaction - all of which can be equilibrium limited depending and then one may have oxidation by CeO2 which will be nearly irreversible in a reductive atmosphere.  Thus to identify the CO conversion, one needs to have some water to produce the hydrogen.  In the absence of hydrogen, all you may be having is the CO2 formation by oxidation.

Any highly sensitive species or highly non sensitive species to the toxicants may be use as bio indicator species. However, Bioindicator species must have fulfil the following characteristics features :

1. Easy to rare under lab. condition.

2. Short life span

3. Repeated generation

Acetylene and isopropene have been mostly reported as emission products from traffic with higher levels around noon, or at times with corresponding higher traffic volumes. Check out some articles of Agnes Borbon, http://www.lisa.univ-paris12.fr/fr/component/comprofiler/userprofile/aborbon or via researchgate. 

Hello

There is no physical reason to say that 2015 will be warmer than 2014 since the interannual variability of global mean temperature is only weakly constrained by the long term warming due to anthropogenic forcing, which is a "slow" change when viewed from this time scale. In 2015, if ENSO switches to a cold event (but neutral conditions is more probable -see IRI forecasts-) and solar constant still decreases till the end of the current cycle 24, we have at least two sources of transient cooling for 2015 vs 2014 -and it is difficult to predict for other possible sources of internal variability-. The switch to cold ENSO could easily provide a -0.1°C signal in global mean temperatures (and solar constant decrease would add few extra hundredths at maximum). So even if all other conditions are constant, this could cool 2015 vs 2014 but it remains of course that it won't change the warming signal related to greenhouse gases increases.  

Vincent

The Government of Alberta site listed at the top of the first responses is a good one. I have worked with researchers in this group on poultry barn environments. We looked at respiratory disease incidence as it related to the dust composition of the barn, and litter treatments to control barn dust. I did a lot of the early microscopy work to characterize the dust in various barn environments.  I was working with John Feddes, who joined this group after he retired from the University of Alberta. I recommend looking up some of his work to get you started. They have also looked at worker health and dust from farm-types other than poultry. 

No, that is not what I said.  BaO is commonly used as an adsorbent within commercially avaialble source emission control systems (e.g., NOx adsorption catalysts, often as Pt-Rh-BaO-Al2O3) that operate primarily under net oxidizing conditions.  NOx and SOx are selectively adsorbed under net oxidizing conditions and released under net reducing, high temperature conditions.  With proper sizing, storage of NOx and SOx can be >99% until adsorption sites become saturated.  H2O and CO2 are also a components of the gas streams that these systems are used with but adsorption strength is much higher for SO2 and NO2.  CO2 is adsorbed but, depending on the temperature, the carbonates formed on BaO are relatively unstable.  At about 200C and above, NO2 and SO2 rapidly displace carbonate and form stable barium nitrate and barium sulfate and CO2 is released.  Emissions control systems with BaO NOx storage are mass produced in the U.S. as part of the NOx emissions control systems on small to medium-sized diesel trucks.

Hi Dmitry,

To me it seems that you want to compare results that have some degree of dependence, using the same model and emissions for each run. In that case I would suggest to use the paired t-test.

The correlation between aerosols at the surface and the total column AOD is highly variable over time and space. It is relatively good for some areas and extremely weak for others. The main thing is to consider is the fraction of the total AOD that is located in the mixing layer, i.e. close to the ground. For background arid conditions and low AOD, the correlation is very weak, so you should not use it.

The catalytic effect of metals was already the reason to use manganese in  two step oxidation procedure decades ago

Have a look at the BS EN 14385 standard. Normally quartz filters require digestion in HF (hydrofluoric acid) as well as nitric - be vey careful with HF, check the MSDS!

Do an inital digestion in 3 ml HNO3 + 2 ml HF at 200C, minimum power 800W for at least 15 minutes. Then remove the vessel from the microwave and allow to cool, then carefuly open the vessel and add 20 ml deionised water and 20 ml boric acid (5% mass content). Replace the vessel in the microwave and heat again for 10 minutes at 200C.

After this, allow to cool and transfer to a flask etc for analysis.

Be very careful with the HF, check all safety information first before using any!

Make sure you have antidote gel to hand in the lab.

Make sure the samplers are not directly exposed to sun, rain or to very strong wind. Make moreover sure that you record the average temperature during the period the samplers are exposed as you might have to correct the uptake rates in case the temperature is very different from 25C.

Hello Luis, I believe we have met once. I think this is a very good question. EPA has been considering this for many years now. I am uncertain about the direction they will go. The strongest evidence for a health effect appears to come from the toxicology literature. However, EPA makes its decisions based on a wider range of evidence, including the epidemiological literature. We know that such epidemiological data is challenging to collect for ultrafines since their concentrations are much more variable in time and space than fine particulates (PM2.5). Such monitoring networks for ultrafines are simply not well established in the United States, which means that the epidemiological studies necessary to support an ultrafine PM standard are quite limited and would need to come from other parts of the world, particularly the UK or other countries in continental Europe. Another fact that is hard to dismiss is the recent review of the evidence of health effects of ultrafine particles from the Health Effects Institute. This came to a fairly weak conclusion and argued that more evidence on ultrafine particles is needed. It emphasized the need for epidemiological evidence, as I have highlighted here. You might consider reading through the HEI review if you have not already. This is available on their website at http://pubs.healtheffects.org/view.php?id=394. I hope this answer is helpful to you.

It’s very important to carry out sampling in that condition because it’s representative of local climate. Where I live it rains all year, but not continuously. Always you can sample. All depends of what you are looking for, in others words, the purpose of monitoring. What, when and how to sample is matter of your monitoring program. The program between other things, depends on what pollutants you want to measure (as in before answers have been told), which sources you are evaluating, which sampling devices you have, and the frequencies and duration of rain. The design of a monitoring program involves many aspects and it should respond to the features of each situation. Based on my professional experience, I can tell you that it’s essential to sample gases from open biogenic sources under rain event. Rain showers or long rains produce layer mixing in these sources and consequently, large emission of gases that are before trapped in bottom layers, emissions as results of pH change and from other processes. Then, gas emission and outdoor concentrations can reach very high values. Without more details about your need and situation is very difficult to help you.

The mycorrhizal inoculum propagation is implemented using sterile soil, in which a grass is sown, such as B. decumbens like a trap crops. B. decumbes is good for Glomus and Scutellospora. After the plant is established, is subjected to drought period with occasional watering to stimulate sporulation. From these trap crops AM, the spore count is done to check the quality.

PBL height can be derived from satellite GPS RO data. Some papers I have come across on the subject are listed below. However I have no specific information about where this data can be obtained.

von Engeln, A., J. Teixeira, J. Wickert, and S. A. Buehler (2005), Using

CHAMP radio occultation data to determine the top altitude of the planetary boundary layer, Geophys. Res. Lett., 32, L06815, doi:10.1029/2004GL022168

Sokolovskiy, S., Y.-H. Kuo, C. Rocken, W. S. Schreiner, D. Hunt, and R. A.

Anthes (2006), Monitoring the atmospheric boundary layer by GPS radio

occultation signals recorded in the open-loop mode, Geophys. Res. Lett.,

33, L12813, doi:10.1029/2006GL025955.

Sokolovskiy, S., C. Rocken, D. H. Lenschow, Y.-H. Kuo, R. A. Anthes,

W. S. Schreiner, and D. C. Hunt (2007), Observing the moist troposphere

with radio occultation signals from COSMIC, Geophys. Res. Lett., 34,

L18802, doi:10.1029/2007GL030458

Hello, here is what you are looking for: http://cerea.enpc.fr/polyphemus/applications.html

Polyphemus is an open source air quality modeling platform, including Gaussian plume and puff models.

If you email me (r.m.harrison@bham.ac.uk), I will send you a published paper with a peer-reviewed method for smaller air samples collected on 47mm filters.

I think climate induced chemical weathering of the overlying soil may be an important reason in natrural situation. If there are heave meta pollutions in the surrounding environment, they may be recorded in speleothems. Recently, we found a stalagmite from central China have recorded the Pb pollution in the environment because of Lead mining process during the last 30 years in this area.

Addition:

nitric acid is the end product of the oxidation of the nitrogen oxides in the atmosphere.

We measured nitric acid concentrations in Atlanta. In the Netherlands almost all nitric acid is neutralized by ammonia. The resulting ammonium-nitrate is a solid material, however so hygroscopic that this compound is indeed present as microdroplets. Also this investigated in great detail.

Harry

Good suggestion. Will do!

Yogesh, you can use CALINE4 model for vehicular emission prediction modelling. it's free version is also available. but i m not sure if it's free version can be used for street canyon modelling.

No dear, for a tunnel VOC car emission study for which I need to know the CO2 background at the moment of the measurement

As you can see in the previous entrée this has been answered already over 30 years ago. In addition to the publications mentioned there are dozens of free publications on the web that you can read. Just start to GOOGLE (you should have done so before asking us)

Here's the attachment.

Also check out:

ARAI (2009). Source profiling for vehicular emissions. Report Number ARAI/VSP-III/SP/RD/08-09/60 ; prepared by Autmotive Research Association of India, Pune, India, http://www.cpcb.nic.in/Source_Profile_Vehicles.pdf.

Sethi, V.; Patil, R.S. (2008). Development of Air Pollution Source Profiles - Stationary Sources Volume 1. prepared by Indian Institute of Technology, Mumbai, India, http://www.cpcb.nic.in/Source_Emission_%20Profiles_NVS_Volume%20One.pdf.

Sethi, V.; Patil, R.S. (2008). Development of Air Pollution Source Profiles - Stationary Sources Volume 2. prepared by Indian Institute of Technology, Mumbai, India, http://www.cpcb.nic.in/Source_Emission_Profiles_NVS_Volume%20Two.pdf.

Try http://lwf.ncdc.noaa.gov/oa/climate/climatedata.html

Glaciers have been melting for centuries so they are an indicator of natural warming.

Recent temperature data show a leveling off or even slight decrease in global temps.

Solar and wind will not provide enough power in many locations around the globe.

The best solution may be eliminating politicians from bloviating so much. The sure method is to blow up our sun. Then we will have about 8 minutes before everyone turning into popsicles.

It is very common error to try to spike too high concentration of hydrophobic analytes. You must look up the water solubility and never try to spike higher. It would be pointless and wrong to use too high concentrations. Acetonitrile is ok but as small amount as possible.

FYI: The National Academies Press just released Opportunities and Obstacles in Large-Scale Biomass Utilization: The Role of the Chemical Sciences and Engineering Communities: A Workshop Summary. It should address some of the issues for here is the US.