Dear USEtox team,
I am assessing the environmental impacts of using pesticides on agricultural land and wanted to include ecotoxicity by using USEtox. At the moment I am assuming that 100% of the emissions end up in agricultural soil, which I know do not represent the reality where some of the pesticide is going to air and some taken up the plant etc. Anyhow. First, I wonder what fate USEtox really include for emissions to this compartment. Does it roughly consider what is bound to the soil and calculates the part of the emission that leave the agricultural soil and ends up in freshwater? Have I then understood it correctly? Does it include some other transfers between compartments, or less?
Secondly, I wonder about emissions to air. In general. For confirmation, is it also here that the model estimates the part of the emission that ends up in freshwater, where the actual exotoxic effect occurs? Not including any effect on organisms from air-exposure? And the same for soil and organisms living there? Due to the fact that most analysis on ecotoxic effects are done in water-medium?
Just to clearify some things.
Thanks in advance!
Johanna
Thank you for your question!
Assuming that 100% of applied pesticides is allocated to emission to soil (on-field) is what is used in Ecoinvent so far as default. However, this does not reflect realistic conditions, which is why we are currently working on a procedure to more realistically reflect how applied pesticides can be allocated to different emission compartments. More information about this process can be found on the Tox-Train project website, where we will link all related publications upon their official publication date.
As for the "fate in soil", USEtox considers all main relevant physicochemical processes in soil including degradation and transfers from and to air and freshwater. This is reflected in the matrix of first order rate coefficients in the USEtox model file (version 1.01), sheet "Run", cells "D24:N34", where all non-zero off-diagonal elements represent a specific transfer process between two adjacent compartments and where all main diagonal element represent the bulk loss for each compartment including all transfers from a compartment to adjacent compartmens and addtional losses via advection and degradation. The same applies to emissions into other environmental compartments like air. The processes are further explained in Henderson et al. (2011).
As for ecotoxicological effects, so far only effects on freshwater ecosystems are considered in USEtox. Further information on ecotoxicological effect factors are given in Henderson et al. (2011).
Dear USETox team,
I have a question related to that posted by Johanna some time ago. I am assesing the environmental impact of a agricultural good applying the ENVIFOOD Protocol. To asses the distribution of the pesticides to the environmental compartements I used the PestLCI 2.0 model that provides the final fate of the pesticide to air, surface water and groundwater. I wonder how these tools communicate with each other considering that PestLCI takes into account the emissions only to the above-reported compartments and it does not consider emissions to soil outside the technosphere.
I read the documentation about PestLCI and it clearly specifies that the model output can be handled by characterization models such as USEtox.
Thank you in advance for any help you could provide.
Gioia
Thank you for your question!
In principle, if there are models predicting emissions from pesticides applied to agricultural fields, the way to combine the output of these models with USEtox is to multiply the applied mass with the fraction reaching a specific environmental compartment (as e.g. given as output in PestLCI 2.0) and further multiply with the emission compartment-specific characterization factor from USEtox.
As an example, if there is a fraction of 20% of applied pesticide mass of 10 kg that is reported in PestLCI as being emitted to air per year, the result of 10 kg/yr x 20% = 2 kg/yr can be seen as emission to continental rural air in USEtox and be multiplied for the specific pesticide with the respective characterization factor. If PestLCI or other emission models report fractions lost to more than 1 compartment, the results of multiplying applied mass, fraction lost to compartment i and characterization factor for an emission in compartment i can be summed up to yield an overall impact potential per pesticide.
For specific details of the output of PestLCI, please consult the model developers.