4 Recommendations and Outcomes from Data Analysis
When compiling data to do this analysis, it became obvious that some articles had to
be omitted, because there was a lack of important information needed to compare
data between studies. Basic guidelines for controlled uptake and translocation
studies, including relevant properties of the compound, the plant and the environment, are crucial to produce valid results. Indeed, comparability and reliability of
scientific data have become burning topics recently and therefore were discussed by
many publishing and governmental agencies, which are concerned about data
integrity and how data can be made “available” for all stakeholders. Accordingly,
a resume of recommendations for future studies might be:
A crucial parameter is the concentration applied in water or soil at the beginning
of each study as theoretical and analytical value. In several articles where both
concentrations were provided, theoretical and practical concentrations varied significantly for specific compounds. In any case, similar concentration units (expressed
in fresh weight or dry weight) should be provided, to better relate data expressed in
the same units.
In case additional irrigation or replenishment of nutrient media is needed, during
the time course of the experiment, authors should mention the volume of water
added, frequency of occurrence and if irrigation water was previously spiked with
pharmaceuticals. Additionally, the quantification of the spiked irrigation water is a
crucial information to calculate the exact concentration to which the plant was
exposed. This is very important when estimating the BCF, since the concentration
in nutrient media/soil is always considered as a base. In many cases, authors only
relate its value to the concentration at T0, which finally leads to an overestimation of
BCFs. Also, if the nutrient media is completely renewed, the concentration before
and after removal should be measured and mentioned. For kinetic studies, it is
moreover important to quantify the concentration in the nutrient media/soil at each
sampling time, in order to relate it to the concentration in the plant at that specific
time point and avoid wrong BCF assumptions.
In all the cases, pH measurements – in nutrient media or in pore water and soil –
are recommended at least for each time point of collection. Some chemical properties (i.e. pKa and log Dow) of selected compounds are dependent on the measured
pH values; this is central when compounds change their ionic status easily in a very
narrow pH range.
Moreover, authors should always consider using different controls, i.e. the inclusion of negative controls (where no plant is included in the spiked nutrient media/
soil, which is used to evaluate the adsorption and potential degradation along the
study) and the plant in a non-spiked situation (to evaluate the plant growth performance in normal conditions).
For soil studies, measuring soil properties besides pH, like percentage of humidity
and organic carbon content plus the soil porosity and texture, is recommended to
enable the comparison of studies and diminish the bias.
130
Y. Bigott et al.
When compiling data to do this analysis, it became obvious that some articles had to
be omitted, because there was a lack of important information needed to compare
data between studies. Basic guidelines for controlled uptake and translocation
studies, including relevant properties of the compound, the plant and the environment, are crucial to produce valid results. Indeed, comparability and reliability of
scientific data have become burning topics recently and therefore were discussed by
many publishing and governmental agencies, which are concerned about data
integrity and how data can be made “available” for all stakeholders. Accordingly,
a resume of recommendations for future studies might be:
A crucial parameter is the concentration applied in water or soil at the beginning
of each study as theoretical and analytical value. In several articles where both
concentrations were provided, theoretical and practical concentrations varied significantly for specific compounds. In any case, similar concentration units (expressed
in fresh weight or dry weight) should be provided, to better relate data expressed in
the same units.
In case additional irrigation or replenishment of nutrient media is needed, during
the time course of the experiment, authors should mention the volume of water
added, frequency of occurrence and if irrigation water was previously spiked with
pharmaceuticals. Additionally, the quantification of the spiked irrigation water is a
crucial information to calculate the exact concentration to which the plant was
exposed. This is very important when estimating the BCF, since the concentration
in nutrient media/soil is always considered as a base. In many cases, authors only
relate its value to the concentration at T0, which finally leads to an overestimation of
BCFs. Also, if the nutrient media is completely renewed, the concentration before
and after removal should be measured and mentioned. For kinetic studies, it is
moreover important to quantify the concentration in the nutrient media/soil at each
sampling time, in order to relate it to the concentration in the plant at that specific
time point and avoid wrong BCF assumptions.
In all the cases, pH measurements – in nutrient media or in pore water and soil –
are recommended at least for each time point of collection. Some chemical properties (i.e. pKa and log Dow) of selected compounds are dependent on the measured
pH values; this is central when compounds change their ionic status easily in a very
narrow pH range.
Moreover, authors should always consider using different controls, i.e. the inclusion of negative controls (where no plant is included in the spiked nutrient media/
soil, which is used to evaluate the adsorption and potential degradation along the
study) and the plant in a non-spiked situation (to evaluate the plant growth performance in normal conditions).
For soil studies, measuring soil properties besides pH, like percentage of humidity
and organic carbon content plus the soil porosity and texture, is recommended to
enable the comparison of studies and diminish the bias.
130
Y. Bigott et al.