Phytoscreening of HCH contamination by broad-leaf trees. Using cheap, handy, and environmentally friendly techniques to indicate HCH presence in the subsurface.
Phytoscreening of groundwater HCH contamination by broad-leaf trees is an indicative method for site characterization. In the early phases of site surveys, it can replace standard procedures of reaching groundwater for analytical purposes (such as hydrogeological wells drilling or direct push probes penetration). In phytoscreening, trees are used as active pumps that deliver groundwater from the subsurface to the canopy. Samples are usually collected from the tree trunk at 130 cm height in a non-destructive manner for the tree.
Preferentially, broadleaf trees above 20 years of age should be used for sampling in places, where the spreading of HCH contaminated groundwater is suspected. For persistent pollutants such as HCH, the year-long presence in tree biomass was documented.
In the past 5 years, it was implemented in the Environmental Chemistry Department at CxI, Technical University of Liberec (TUL) for helping solve EU projects AMIIGA and LIFEPOPWAT. This laboratory is ready to provide training in using phytoscreening of HCH for interested parties, such as environmental consultancy companies or laboratories. Also, the results of TUL phytoscreening activities were published several times at scientific conferences, workshops, and webinars (key author: Pavel Hrabák).
The phytoscreening technique can be demanded by site owners or environmental inspectorates as a first, relatively cheap, and environmentally friendly step in site surveys.
Resources needed
Analytical laboratory is needed, that is equipped for organic pollutants determination. Instruments such as GC-MS are necessary for the analytical step. Sample collection should be performed by trained personnel. Unexpensive utilities such as accu borer with replaceable drills are needed.
Evidence of success
During AMIIGA project (2016-2019) a HCH megasite Jaworzno in Poland was surveyed. An indicative correlation was found for groundwater and tree samples, including low background concentrations (see the image below).
At another HCH site, Hájek in the Czech Republic, the distribution of HCH was studied in the whole year study, bringing information on seasonality changes and age/hight HCH distribution (conference posters are available on the links below).
Difficulties encountered
Coniferous trees are much less sensitive as phytoscreening HCH indicators than broadleaf. Acquiring samples (drilling into trees) should be authorized by local municipalities. Phytoscreening´s use is limited to sites with a shallow aquifer (< 15 m below the surface) and tree vegetation presence.
Potential for learning or transfer
The potential of transfer is large since there are many HCH sites in EU with suitable aquifer morphology, vegetation coverage, and unknown areas of pollutant plume spreading. In such situation, the sampling campaign can be performed directly by Technical University of Liberec (TUL). Or, personnel from other laboratory/university/company can be trained at TUL or online to perform phytoscreening independently. Phytoscreening can quickly and cheaply bring preliminary indication on HCH groundwater plume shape that helps with further decisions on monitoring and remediation design. Thereby, phytoscreening can save significant costs.
