Kale is considered a superfood and is a bioindicator for air pollutants and contaminated soils. Active biomonitoring, with biologically standardized measurement methods, can be used to determine and assess the effects of air pollution and other stresses on the environment and humans.
Properties of kale as a bioindicator
Kale is particularly suitable as a bioindicator for determining persistent, organic pollutants and immission-related inputs of heavy metals and other air pollution.
As a bioindicator , it is representative of other leafy vegetables such as spinach, chard, lettuce, rocket, lamb’s lettuceand others. It has highly dissected leaves with large surfaces. These have a thick wax layer that binds organic pollutants particularly well. Dusts and dust particles can collect on its leaf surfaces, which can be easily removed. The waxy leaf surface is particularly good at binding lipophilic, fat-soluble and organic pollutants. The kale is washed and processed after harvesting. The samples are then analyzed for organic components such as PAHs (polycyclic aromatic hydrocarbons), PCBs (polychlorinated biphenyls), dioxins or furans (PCDD/PCDF). With its special properties, kale can accumulate these pollutants particularly easily.
Guideline VDI 3957 Sheet 3 for the evaluation of pollutant levels
Guideline VDI 3957 Sheet 3, published by the VDI/DIN Commission on Air Quality Control (KRdL) – Standards Committee, describes the use of kale as a bioindicator. It regulates standardized procedures for assessing pollutant levels in food crops grown for human consumption. This guideline only applies to the non-commercial cultivation of food crops.
Guideline VDI 3957 Sheet 3 enables systematic investigations into the accumulation of harmful substances and the assessment of their effects on humans and the environment. It describes the standardized procedures and the necessary technical precautions for the cultivation and exposure of kale. Furthermore, it regulates the sampling, preparation of the plant sample and evaluation of the determined pollutant content.
Biomonitoring with kale – examples
Biomonitoring of kale can be used to determine pollutant levels in even highly contaminated small-scale areas.
Examples of biomonitoring with kale in small spaces:
- Suspected cultivation of kale or other crops contaminated with pollutants that may be harmful to health if consumed regularly
- Investigation of air pollution from polluting operations such as coking plants
- Determining the environmental impact of air traffic with heavy metals on airport operations
- Environmental pollution from port operations with polychlorinated biphenyls (PCBs)
- Immission effects of polycyclic aromatic hydrocarbons (PAHs)
Biomonitoring with kale was initially developed for the immission effects of polycyclic aromatic hydrocarbons (PAHs) . As early as the 1990s, success controls were carried out on measures implemented to reduce polychlorinated dibenzodioxins and dibenzofurans. Later, organic substances and substance groups and inorganic pollutants were also recorded using biomonitoring.
Measure of the LANUV NRW – Biomonitoring
The North Rhine-Westphalia State Agency for Nature, Environment and Consumer Protection(LANUV NRW) takes action if the respective immission control authority suspects that food plants from allotment gardens and home gardens have been exposed to pollutants. Guideline VDI 3957 Sheet 4 (in preparation) regulates biomonitoring for this procedure with kale.
Certain organic components such as polychlorinated biphenyls (PCBs) or polycyclic aromatic hydrocarbons (PAHs) can be sampled both outdoors and indoors using special GSA measuring devices.
GSA measuring devices Gravikon PM 4-2 measures PCBs and PAHs
The Gravikon PM 4-2, which is available from the GSA measuring devices online store, has been specially developed for specific sampling of organic components such as PCBs and PAHs in accordance with VDI 2463 Sheet 7. In addition to stationary measurements, the PM 4-2 can also be used for personal samplers via the rechargeable battery. The measuring devices has a regulated high air flow rate of 4 m³/h. With this high air flow rate, even low concentrations of pollutants can be measured, especially in smaller rooms or cabins. Suitable spare parts are available for the measuring device PM 4-2 for various measurements of harmful substances, including particle measurements of different dust fractions such as A-dust or E-dust.
Kale as a bioindicator for pollutants: answers to frequently asked questions
1. which specific pollutants can kale bind particularly well?
Kale is particularly good at absorbing persistent organic pollutants and heavy metal emissions. The waxy leaf surface of kale allows these pollutants to accumulate. In particular, these are substances such as polycyclic aromatic hydrocarbons (PAHs), polychlorinated biphenyls (PCBs), dioxins and furans.
2. how is the kale processed and examined after harvesting?
After harvesting, the cabbage is thoroughly washed and analyzed for organic components. The analysis methods include chromatographic procedures, mass spectrometry and other laboratory techniques. The samples are tested for PAHs, PCBs, dioxins and furans in order to quantify the pollutant load.
3. are there differences in the accumulation of pollutants between commercial and non-commercial cultivation of kale?
Yes, there are differences. In commercial cultivation, pesticides and fertilizers can be used, which influence the level of pollutants. Self-cultivation in your own garden tends to produce fewer pollutants, as fewer chemical substances are used. Guideline VDI 3957 Sheet 3 regulates the assessment of pollutant levels in home-grown food crops.
4. what specific environmental impacts can be determined by biomonitoring with kale?
Biomonitoring enables the identification of pollutants in heavily polluted small-scale areas. This can help to improve air and soil quality. Examples of successful applications include the identification of industrial emissions or the monitoring of traffic emissions in urban areas.
Sources:
Image source: 123rf.com © belchonoc Image no. 137792290
www.bottrop.de/wohnen-stadtquartier-verkehr/pak-messungen/aktuelles/laufende-meldungen/ergebnisse-der-gruenkohlmessungen-liegen-vor.php (example of pollution from a coking plant in Bottrop)
blog.vdi.de/gruenkohl-ein-verkanntes-superfood
www.de.wikipedia.org/wiki/Grünkohl
www.de.wikipedia.org/wiki/Biomonitoring
www.lanuv.nrw.de/umwelt/luft/wirkungen-von-luftverunreinigungen/wirkungen-auf-pflanzen/biomonitoring/gruenkohlexposition
www.lanuv.nrw.de/fileadmin/lanuv/luft/untersuchungsprogramme/Dortmund_Silikon/19_Dortmund_Bericht_2021_22-02-07.pdf (Example of an immission load
of food plants in a Dortmund study area)
www.vdi.de/fileadmin/pages/vdi_de/redakteure/richtlinien/inhaltsverzeichnisse/3478312.pdf