Air sampler systems for environmental monitoring

Welcome to the UKCEH ALPHA^® and DELTA^® sales and service offering.

The links below will expand when you click on them to reveal the relevant information.

Important Change Note

Change Note

Due to the ALPHA^® membrane material being discontinued we are supplying a new style of membrane from October 2020. This new membrane has been selected based on excellent results of intercomparison testing with the old style of membrane.

ALPHA^® PTFE1020 will have a slightly different product specification to the old style and, as such, the uptake rate will be different. The most recent published calibrated uptake rate is the 2021 value: 0.0039701, which has been determined by calibration of ALPHA^® PTFE1020 against the UKCEH DELTA system at three UK sites in 2021 (data for this calibration will be published on the EIDC).

Due to this being a limited dataset UKCEH recommends increasing the uncertainty of any measurements using PTFE1020 to 20% until further notice. Only one type of membrane should be used for an entire network, project, experiment or study.

If you have any questions or want more information regarding this change please get in touch with us by email.

Additional information for analysis projects

Information on the membrane style to be used will be clearly provided at the quoting stage or in email to the project lead if a change is required within a project duration. Changes of membrane style will be avoided within project durations to the best of our ability.

Enquiries and Orders

We are working on a new online ordering form. In the meantime, please email cehairquality@ceh.ac.uk with your order!

Ammonia and air quality background

Ammonia is a highly reactive gas, an excess of which can lead to eutrophication and acidification of terrestrial and freshwater ecosystems, biodiversity loss and the formation of secondary particulate matter. It originates from both natural and anthropogenic sources, including agricultural related emissions such as manures, slurries and fertiliser application.

Ambient ammonia monitoring can be carried out with two UKCEH products:

ALPHA^®
DELTA^®

The DELTA^® system can also be used to actively sample a wider range of atmospheric species.

ALPHA

ALPHA^®

The UKCEH ALPHA^® (Adapted Low-cost Passive High Absorption) sampler is a system designed for the measurement of the concentration of ammonia (NH₃) in air. It has been used for over 10 years on the UK national ammonia monitoring network and designed for ecosystem impact assessment studies. It is a simple to use, low cost method which does not require electricity. It is useful as a complementary method for assessing spatial differences in source areas where NH₃ concentrations may vary hugely. It does not sample ammonium aerosol.

Suitable range of ammonia concentrations:

Monthly monitoring = 0.03 - 100 ug NH₃ m^-3
Weekly monitoring = 0.05 - 400 ug NH₃ m^-3

All of the plastic components of the ALPHA^® samplers, including the PTFE membranes, can be cleaned and reused. The only component that is single use is the filter paper.

UKCEH can provide parts for the samplers, which you can prepare and coat yourself, or costings for our laboratory service offering and science advice which includes prepared samplers. Contact us with your order.

Sampler Background

The passive sampling system consists of three replicate ALPHA^® samplers attached to the underside of a shelter at about 1.5m height above ground. The samplers operate on the principle of diffusion with an acid-coated filter which serves to capture the ammonia. Replicate tubes are used in order to give more reliable results.

Exposed samples are stored at 4˚C until analysis. The chemical of interest captured on the filter paper or denuder tube is extracted, usually into deionised water, which is then analysed. At UKCEH we use the SEAL AA3 for ammonium analysis or Ion chromatography for other chemicals of interest. We use a set of standards and quality control samples to ensure accurate results.

DELTA

DELTA^®

The UKCEH DELTA^® system is a low-volume denuder air sampling method for long-term sampling of ammonia and ammonium in the atmosphere. The system can also be extended to sample acid gases (NH₃, HNO₃, HCl, SO₂) and aerosols (NH₄⁺, NO₃^-, SO₄^2-, Cl^-, Na⁺, Ca²⁺, Mg²⁺). It requires power (wind solar systems available) and a user with a good foundation in scientific instrumentation to operate correctly.

DELTA systems and parts can be purchased from UKCEH and we may have a limited number of instruments available for short term (<1 year) hire.

Background to the DELTA® system

When a laminar air stream passes through the coated denuder, gases of interest react with and are captured by the coating. The coating is later extracted and analysed in a laboratory. Aerosols pass through the coated tube uncollected and are captured by coated filters placed downstream of the denuder. The separation of aerosol from gaseous components is achieved due to the much more rapid diffusion of gaseous species to the tube wall compared with that of particles.

Low, stable air sampling rates of 0.2-0.4 / min^-1 are achieved using small air pumps, with air volumes being measured by a high sensitivity dry gas meter. The low sampling rate means that short glass denuders can be used, which allows easy exchange of samples through the post.

Image above shows example sample train configuration for ammonia/ammonium measurements.

Frequently Asked Questions

Ammonia Science Background

Ammonia science background

Can I use ALPHA samplers to measure emissions from test plots of different fertiliser treatments?

ALPHA samplers can be used in conjunction with a computer model and additional data (local environmental conditions) to measure emissions from test plots. More information on this (FIDES method) can be found here:

Loubet, B, Génermont, S, Ferrara, R, Bedos, C, Decuq, C, Personne, E, Fanucci, O, Durand, B, Rana, G, Cellier, P. 2010. An inverse model to estimate ammonia emissions from fields. European Journal of Soil Science 61, 793–805. https://doi.org/10.1111/j.1365-2389.2010.01268.x

And

Loubet, B, Carozzi, M, Voylokov, P. Cohan, J-P, Trochard, R, Génermont, S, 2018. Evaluation of a new inference method for estimating ammonia volatilisation from multiple agronomic plots. Biogeosciences 15, 3439–3460. https://doi.org/10.5194/bg-15-3439-2018

How many sites should I do for my experiment and how far apart should I space them?

It really depends on your experiment, a few common scenarios are detailed below. If you want more help with experimental design you may benefit from one of our training courses. Please email cehairquality@ceh.ac.uk for more information or check the website for the latest course dates.

For validating models we recommend a transect (minimum of 3 locations at logarithmic distances, e.g. 50, 100 and 200m downwind of source) and a background site (e.g. > 300 m upwind of source).
For assessment of impacts on a sensitive ecosystem downwind of a source we recommend a minimum of four locations:
- 1) at least one site between source and receptor,
- 2) one site on edge of reserve
- 3) one site in centre of reserve
- and 4) one site upwind of source as “background”
For a background national or local network ideally you would do emission mapping first to determine the primary emission sources of grid squares and then assign sites. You would want to ensure you sites are representative of the entire area and also have reliable site operators to give a good data set.

For most measurements, sites should be located in a clearing, ideally with at least 50 m clearing all around. In real life this is not always possible, so aim to locate the samplers at a good distance from any building, trees, hedges, structure or topography which could impact the flow of air. The recommended sampling height is 1.5 m above ground or vegetation.

How long should I measure for and how often?

We recommend exposing samples on the monthly (or fortnightly) cycle for at least 1 year to ensure you are catching any seasonal fluctuations of ammonia.

For most experiments we recommended an exposure period of 1 month unless you have very high levels in which case fortnightly durations would avoid sampler saturation.

Can I measure ammonia deposition using the ALPHA samplers?

No, you would need additional information to do calculations or modelling. Please contact cehairquality@ceh.ac.uk for more advice on how to do this.

Where can I find data?

Where can I find Data?

Where can I find the mean annual ammonia background level for my area (UK)?

This information can be found on APIS.

Where can I find the UK Network data?

The UK network data is available on UKAIR website under the NAMN and AGANET networks.

Is there any other ALPHA® or DELTA® data which is openly available?

Other open source ALPHA® or DELTA® data UKCEH produce will now be stored on the EIDC.

Ammonia and human health

I live in a rural area where there is a ‘bad’ smell coming from local agricultural activities can I use ALPHA® samplers to measure the levels?

If you are living in a rural area and having issues with odours the best first step would be to contact your local authority or environmental health body to make an enquiry/complaint. They will then investigate and take appropriate action at no cost to you as a private individual.

Sometimes queries regarding rural smell issues coincide with periods of calm weather. This lack of air movement can allow the concentration of some of the odour causing chemicals to build up and this is the cause of the more noticeable smell rather than any increase in emissions from local farms. Again your local authority or environmental health body are best placed to help you with these issues and take the appropriate action.

Further information

In rural areas ammonia comes from a variety of agricultural sources and also digestates produced from Anaerobic Digestion (farm slurry, food waste etc).

The pH of the digestate is generally higher than farm slurry. The higher pH (on the alkaline side) means that loss of ammonia through volatilisation into the atmosphere may be increased.

Information on best practice for digestate storage and spreading can be found on the Organic Recycling Group website.

As well as the ammonia, there will be other volatiles that will contribute to the pungent smell so if the smell is your first concern you may like to look into commissioning an odour emission survey. This is not something UKCEH currently offers. You can find many consultants online who will be able to offer you quotes for this.

UKCEH can offer costings for ammonia in air passive samplers or vegetation impact surveys. These samplers give a monthly average ammonia in air concentration and we would recommend to measure for a minimum of one year in order to catch the fluctuations in seasonal cycles of ammonia. This type of measurement usually costs in the region of £2000 per year per site for the data only, science advice will have additional costs associated. You would need a number of sites and additional science input to have any possibility of attributing increased levels to one particular source. Vegetation surveys are site dependent and would help to show the impact of changing levels on your local vegetation. These are aimed at protected or sensitive ecosystems such as nature reserves.

Is there a known value where ammonia concentrations have a negative impact on human health?

Please see the government advice on ammonia [PDF]

Ammonia is also known to contribute to particulate matter formation so the information here may also be of some interest.

Order and shipment queries

Order/Shipment Queries

Which coating should I use on my ALPHA® samplers?

Current advice is, if you are not sure, is start with citric acid and run some local trials before beginning any experiment. More detailed advice on preparation is available in the manuals.

Citric acid is suitable for temperate climates, it is currently used across the UK and Europe. Citric Acid has also been used in parts of Africa and India where the climate is also temperate.

Phosphorous acid should be used for hot, dry climates but should be avoided in high humidity conditions.

UKCEH along with partner organisations are starting to look at warm high humidity environments to evaluate the best coating for these regions but we haven’t got a definitive answer yet.

Why is it taking so long for me to receive my invoice?

If you are a new customer it can take up to 10 working days to add you to our systems then another few weeks for an invoice to be generated. Once you are set up on our system future orders should progress much more quickly. We have recently migrated our finance systems so are currently seeing an unusually long delay on invoicing.

Why is shipping so expensive?

We use Royal Mail or an independent courier for small parcels in the UK and independent shipping agents for larger, outside UK or tracked shipments. Prices are set by our courier based on size and weight of shipment.

Shipping also includes the cost of us preparing any customs paperwork and arranging delivery.

How can I pay?

Payment details will be provided for bank transfers on your invoice. Payment is usually in advance of shipment unless you are a regular customer (>1 order per year) and we have set up a credit agreement.

Does anyone else supply this equipment/ service offering?

UKCEH are the sole supplier of the ALPHA® and DELTA® equipment: no other company is permitted or registered with us to supply the goods on our behalf. We will work with import companies for China but they must place the order and be logged as the customer to be invoiced.

No other company is endorsed by UKCEH to install, run, service or perform analysis required for ALPHA® and DELTA® systems. We do provide logged training certificates to attendees of our training courses and you can contact us for an email to verify you attended a particular course.

What is the lead time or orders?

ALPHA® samplers are usually held in stock and for orders <5000 will ship on receipt of payment.

DELTA® systems and parts require construction by our workshop so have a three-month lead time.

You will be informed of any expected delays or longer lead times on submission of your order form.

References and related publications

Martin Nicholas A, Ferracci Valerio, Cassidy Nathan, Hook Josh, Battersby Ross M, di Meane Elena Amico, Tang Yuk S, Stephens Amy C M, Leeson Sarah R, Jones Matthew R, Braban Christine F, Gates Linda, Hangartner Marcus, Stoll Jean-Marc, Sacco Paolo, Pagani, Diego, Hoffnagle John A, Seitler, Eva (2019). Validation of ammonia diffusive and pumped samplers in a controlled atmosphere test facility using traceable Primary Standard Gas Mixtures. Atmospheric Environment, 199. 453-462. DOI: 10.1016/j.atmosenv.2018.11.038

Tang Y Sim, Braban Christine F, Dragosits Ulrike, Simmons Ivan, Leaver David, van Dijk Netty, Poskitt Janet, Thacker Sarah, Patel Manisha, Carter Heather, Pereira M Gloria, Keenan Patrick O, Lawlor Alan, Connolly Christopher, Vincent Keith, Heal Mathew R, Sutton Mark A (2018). Acid gases and aerosol measurements in the UK (1999–2015): regional distributions and trends. Atmospheric Chemistry and Physics, 18 (22). 16293-16324. DOI:10.5194/acp-18-16293-2018

Tang Y S, Braban C F, Dragosits U, Dore A J, Simmons I, van Dijk N, Poskitt J, Pereira M G, Keenan P O, Conolly C, Vincent K, Smith R I, Heal M R and Sutton M A (2018). Drivers for spatial, temporal and long-term trends in atmospheric ammonia and ammonium in the UK, Atmospheric Chemistry and Physics, 18, 705-733, DOI: 10.5194/acp-18-705-2018.

Puchalski M A, Sather M E , Walker J T, Lehnmann C M B, Gay D A, Mathew J, Robarge, W P (2011). Passive ammonia monitoring in the United States: Comparing three different sampling devices. Journal of Environmental Monitoring, 13, 3156.

Sutton M A, Miners B, Tang Y S, Milford C, Wyers, G P, Duyzer, J H and Fowler, D (2001a) Comparison of low cost measurement techniques for long-term monitoring of atmospheric ammonia. J. Environ. Monit. 3, 446‑453.

Sutton M A, Tang Y S, Miners B and Fowler, D (2001b) A new diffusion denuder system for long-term, regional monitoring of atmospheric ammonia and ammonium. Water, Air and Soil Pollution. Focus, 1, Part 5/6, 145‑156.

Tang Y S, Cape J N & Sutton M A (2001) Development and types of passive samplers for monitoring atmospheric NO2 and NH3 concentrations. In Proceedings of the International Symposium on Passive Sampling of Gaseous Pollutants in Ecological Research. TheScientificWorld, 1, 513-529.

Tang Y S, Simmons I, van Dijk N, Di Marco C, Nemitz E, Dämmgen U, Gilke K, Djuricic V, Vidic S, Gliha Z, Borovecki D, Mitosinkova M, Hanssen J E, Uggerud T H, Sanz M J, Sanz P, Chorda J V, Flechard C R, Fauvel Y, Ferm M, Perrino C & Sutton M A (2009) European scale application of atmospheric reactive nitrogen measurements in a low-cost approach to infer dry deposition fluxes. Agriculture, Ecosystems and Environment: NitroEurope Special issue. (133), 183-195.

Training courses

UKCEH have a selection of training courses which we run regularly. We can also run bespoke courses or specific dates so please contact us at cehairquality@ceh.ac.uk to ask about that.

We’ll also update/ advertise any upcoming courses with availability on our Twitter feed.

Example Course Titles:

Ammonia as an air quality pollutant
Ammonia: measurement planning
ALPHA® and DELTA® local site operator (LSO) Training
Laboratory skills for ALPHA® samplers
Laboratory skills for DELTA® samplers
ALPHA® site set up and choosing site locations
DELTA® site set up and site servicing

We do provided logged training certificates to attendees of our training courses and you can contact us for an email to verify that you attended a particular course (in the last three years).

Videos

Diagram showing parts A to I of an ALPHA sampler

Above: Outline diagram of a single ALPHA® sampler and components.

Two images highlighting different components of a DELTA sampler

Detail of components in the monitoring enclosure of the low voltage DELTA® system. An example installation of the low voltage DELTA® system powered by wind and solar in the field is shown on the right. 1: Durable plastic enclosure 2: Sample train holder. 3: Sample inlet 4: Plug-in for sample train heater 5: Gas meter. 6: Rotameter. 7: Pump box