Guidance Document on Field Sampling for SSA Related Research
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Zixia Liua,b, Emmanuel Van Ackera, Colin Janssena,b, Jana Asselmanb

aGhent University, Laboratory of Environmental Toxicology and Aquatic Ecology, Faculty of Bioscience Engineering, 9000 Ghent, Belgium

bBlue growth research lab, Ghent University, Greenbridge, Wetenschapspark 1, 8400 Ostend, Belgium

Release date: NOT-YET-2020


Sea Spray Aerosol (SSA) is generated by the bubble bursting of whitecap waves occurring in the sea surface microlayer (SSML), i.e. on the top layer of 1~1000 µm of seawater (Michaud et al., 2018). It contains mixed salts, organic materials, and marine biogenic. With 71% ocean coverage of the Earth, SSA represents as a major atmospheric aerosol particle type, and an essential source of human inhalable particles in the coastal area. Since the coastal zone (~100 km to the coastline) supports a population that is three times denser than the global average (Crossland et al. 2005), characterization of the SSAs’ concentration, chemical and biochemical composition, and particle size are vital for understanding and evaluating the human health consequences of SSA.

However, studies about the health risks of SSAs majorly focused on the negative health effects caused by extreme ecology events, such as brevetoxins generated during harmful algal blooms, e.g. red tide (Fleming et al., 2009). Yet, limited studies have been done on the potential impacts of SSAs to human health in the coastal area. A recent study reported inductions of apoptosis were observed when human lung cancer cells exposed to natural SSA (Asselman et al., 2019). Although the mechanism of positive SSA exposure effects is still unknown, and we don’t know which compound(s) is (/are) effective in SSA, the research result indicates that there are potential positive health effects at an environmentally relevant concentration of SSA.

Because of the enrichment effect (O’Dowd et al., 2004), the biogenic compounds in the seawater can be concentrated dozens or even hundreds of times. Some of these compounds are believed to be active to human health either positive (Moore, 2015) or nagitive (Guo et al., 1994). Enrichment rate of SSA compounds have been studied in recent decades, most studies focus on the enrichment rate of chemical categories of compounds in SSA (Cochran et al., 2017; Bertram et al., 2018), rather than the enrichment rate of specific compounds related to human health.

We have designed the following long-term sampling guidance to reveal the formation mechanism of human health-related compounds in SSA and hopefully predict the SSA-Human-Health-Index through conventional monitoring methods (remote sensing and weather data).


3.Experiment design (for now, outline only)

  • Remote sensing (RS) data + seawater sample (RV Simon Stevin, algae) -> prediction model of algae density based on RS data.
  • Seawater sample (algae / plankton / bacteria community) + seawater sample (chemical) -> prediction model of seawater specific compound(s) concentration based on microbe composition.
  • Seawater sample (coast, chemical) + SSA sample (coast) -> prediction model of SSA specific compound(s) concentration based on water samples data (enrichment model).
  • Wind and other climate data + SSA sample (coast-inland transections) -> spread model of SSA specific compound(s) based on climate data.


4.1.Site information

Site information listed below should be recorded each time before sampling processes. Sheet-1 gives an example of site information parameters that should be filled in and measured on-site.

4.1.1.General information

For each field sampling, the following information should be recorded:

Parameter Description
SiteInfoID The unique ID for the sampling site information, one ID for each sampling operation (can have multiple samples in one operation).
Date Date for sampling operation.
TimeBegin Time when the sampling operation begins.
TimeEnd Time when the sampling operation end.
Participants Names of the participant in this sampling operation.

Take pictures of the sampling site and the surroundings if possible.

4.1.2. Site location

Geographic coordinates of sampling site should be measured using GPS equipment. Recommended App is My GPS Coordinates (iOS | Android). GPS signal accuracy should be within 100m, otherwise a professional GPS device is needed. The coordinate data should be accurate to 3 decimal places. The distance to coastline should also be in-situ measured and recorded if possible, otherwise, use R script to calculate afterwards.

Parameter Unit Accuracy Description
Latitude °N 3 decimal places Latitude of sampling site
Longitude °E 3 decimal places Longitude of sampling site
D2Coast km 1 decimal places Distance form sampling site to coastline

4.1.3.Wind speed and direction

Wind speed and direction should be measured with WeatherFlow WINDmeter. Measurement should be performed three times: before, during, and after the sampling process. Both average speed and gust speed should be recorded. See HERE for the device user guide.

Figure 4.1.1 Wind speed and direction measurement

Parameter Unit Accuracy Description
WGSpeed1 km per hour 1 decimal place Gust wind speed before sampling
WASpeed1 km per hour 1 decimal place Average wind speed before sampling
WDirection1 ° 1 decimal place Wind direction before sampling
WGSpeed2 km per hour 1 decimal place Gust wind speed during sampling
WASpeed2 km per hour 1 decimal place Average wind speed during sampling
WDirection2 ° 1 decimal place Wind direction during sampling
WGSpeed3 km per hour 1 decimal place Gust wind speed after sampling
WASpeed3 km per hour 1 decimal place Average wind speed after sampling
WDirection3 ° 1 decimal place Wind direction after sampling

4.1.4.Temperature, relative humidity and air pressure

Temperature (dry bulb temperature), relative humidity and air pressure should be measured with WeatherFlow WINDmeter or other professional equipment for measurement.

Parameter Unit Accuracy Description
Temperature °C 1 decimal place Dry bulb temperature in Celsius
Humidity % 1 decimal place Relative humidity using dry and wet bulb thermometer
AirPressure inHg 2 decimal place Atmospheric pressure

4.2.Water sample

This part is adapted and modified from Guide to best practices to study the ocean’s surface and GB 17378.3-2007 Marine Monitoring Code Part 3: Sample Collection, Storage and Transportation

4.2.1.Sea surface microlayer (SSML) sampling screen sampling method

This sampling method is preferred when the wind and waves are not strong. Otherwise, please use the glass plate sampling method.


  • Screen sampling device (mesh size 1 mm2, Lechtenfeld et al., 2013)
  • Polyethylene vessels
  • Funnel

Figure 4.2.1 Mesh screen sampling device

Sampling procedures

  • Rinse the mesh screen, vessels and funnels with acetone and air-dried.
  • Put the rinsed screen into the seawater at an angle, once it is submerged completely in the water, it should be kept horizontal and wait for 30 seconds.
  • Slowly lift the screen vertically out of the seawater.
  • Tilt the screen at an angle, so that the SSML sample can drop into the funnel and finally collected in the vessels.
  • Mark the vessels.

Figure 4.2.2 Mesh screen sampling procedures (modified from Cunliffe et al., 2014) panel sampling method


  • Glass panel sampler
  • Polyethylene vessels
  • Funnel
  • Silicone wiper

Sampling procedures

  • Rinse the glass plate, vessels and funnels with acetone and air-dried.
  • Insert the glass plate vertically into the seawater with the handle and slowly lift it out, keep it vertical during the procedure.
  • Use the wiper to scrape off the liquid adhered to the glass plate, collect it in the vessel via funnel.
  • Mark the vessels.

Figure 4.2.3 Glass panel sampling procedures (from Cunliffe et al., 2014)

a)glass plate sampler with integral PVC handle showing sample collection (courtesy of Manuela van Pinxteren, TROPOS, Germany).
b) squeegeeing a simple plate sampler held with a clean plastic clamp.
c) squeegeeing a glass plate sampler using “clean hands/dirty hands” technique (courtesy of Manuela van Pinxteren, TROPOS, Germany).
d) a glass plate and sample recovery device containing integral Teflon wiper and funnel, based on the design of Hardy et al. (1985).

4.2.2.Surface seawater sampling


  • Vertical water sampler with build-in thermometer
  • Polyethylene vessels
  • Funnel

Sampling procedures

  • Rinse the water sampler, vessels, and funnels with surface seawater at the sample site.
  • Close the water outlet valve of the sampler.
  • Slowly lower the sampler vertically with the rope connected to it, the sampler bottom valve will open automatically when lowered, and seawater flows into the sampler.
  • Continue to lower it untill the top of the sampler completely immersed in sea water, close the upper opening manually and pull the sampler up.
  • Read the water temperature and write it down.
  • Open the water outlet valve of the sampler to collect the water sampler in the vessels via funnel.
  • Mark the vessels.

4.3.Aerosol sample


  • Constant flow vacuum pumps
  • Filters (type to be discussed)
  • Filter holders
  • PVC tubes
  • Ziplock bags
  • Anti-oxidation bags

Filter holder preparation

  • Each time 5 filter holders will be prepared, 4 for actural sampling and 1 for blank (carried with other three and).
  • Wash the filter holders and underdrain discs (Figure) with deionized water and then rinse with acetone. Remove residual acetone using purified high-pressure air.
  • Use clean tweezer to place a filter on the underdrain discs fitted in the filter holder, note that the front of the filter is facing outward (to the air inlet).
  • Make a small mark on the filter edge, align the mark on the filter with the valve on the outside of the filter holder, and close the filter firmly.
  • Put the prepated filter holder into ziplock bag for latter usage.

Sampling procedures

Field Setups:

  • Setting up the stand on a solid foundation, no block in the upwind direction.
  • Mark the filter holders as either sample or blank.
  • Clip the prepared filter holders on the stand, at a hight around 170 cm. Make sure the air inlet facing the upwind direction, and the valve on the outside of the filter holder is up right.
  • Connect each filter holder to a vacuum pump with PVC tubes.
  • If a diesel generator is used, it needs to be placed in the downwind and as far away from the sampling area as possible.

Schematic diagram of sampling devices, inspired by Sam Baelus’s Master’s dissertation and Emmanuel

SSA sample collection:

  • Open the air sampling pump with a flow rate of 10 L·min-1 for about 200 minutes, till 2000 L air flow collected (calculated by pump build-in counter).
  • Keep the upwind clear without people and make notes if there is anyting wrong.
  • After stoping the pump, remove the tubes on the filter holds and put it into ziplock bag with anti-oxidation bags.

4.4.Ecological survey


5.1 SSML sample storage

The SSML samples should be analysised as soon as possible. Before that it should be stored in dark at 4°C without any pre-treatment (K. Schneider-Zapp et al.,2013).

5.2 Surface seawater storage

For different purpose, the seawater samples will be saperate into two group for preservation.

5.2.1 Filtration and acidification

  • Filtrate the water sample with 0.45 µm membrane filter.
  • Acidify the sample with pure nitric acid.
  • Place the filter samples in petridishs and seal with parafilm.
  • Store the filter samples and acidified water samples in -40°C.

5.2.2 Freezing

  • Using cryoprotectant to protect organism in seawater from being damaged by ice crystals.
  • Store the seawater samples in -40°C.